tag:blogger.com,1999:blog-8439124741169172562024-02-21T23:09:16.479-08:00Keep In TouchKeepOnTouchhttp://www.blogger.com/profile/07899435487244202636noreply@blogger.comBlogger77125tag:blogger.com,1999:blog-843912474116917256.post-87678797690567100062012-05-24T08:01:00.000-07:002013-03-19T09:11:32.201-07:00Keep in touch with your Friends<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjd-ilbiHAKuCa-8C3C67xHayohPbq9Ax_02QKEyKj0aEhnKxSb2QmxCG4hVhX6FSNJ82GUDAg-Z0H04wqLlwKSzKYEqnugWJnGvbf9lcxJgREF6jnH-s1E18_FF0XjCLJBf-ADA23FGvpY/s1600/Keep+in+touch+with+your+Friends.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Keep in touch with your Friends" border="0" height="190" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjd-ilbiHAKuCa-8C3C67xHayohPbq9Ax_02QKEyKj0aEhnKxSb2QmxCG4hVhX6FSNJ82GUDAg-Z0H04wqLlwKSzKYEqnugWJnGvbf9lcxJgREF6jnH-s1E18_FF0XjCLJBf-ADA23FGvpY/s320/Keep+in+touch+with+your+Friends.JPG" title="Keep in touch with your Friends" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Keep in touch with your Friends</b></span></td></tr>
</tbody></table><span style="font-size: large;"> When friends move away, it's hard to keep in touch with them. You both get busy with your separate lives and don't have the time to catch up with each other. Nonetheless, it's important to keep in touch with friends.Here are some ideas for keeping in touch with your buds. </span><br />
<span style="font-size: large;"><br />
<span class="fullpost"> <span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> <b>Phone Call</b> </span><br />
</span></span><span style="font-size: large;"><span class="fullpost"> </span></span><br />
<span style="font-size: large;"><span class="fullpost"> Simply pick up the phone and call whenever you can - it doesn't have to be a long phone call. Just a quick 5 minute call can get you caught up with your pal, and he or she will know you were thinking of them. Let her know that you want to know what's going on with her. They're probably interested to hear about what your up to, too!</span></span><span style="font-size: large;"><span class="fullpost"> </span></span><br />
<span style="font-size: large;"><span class="fullpost">Make a commitment to call each of your friends at least once a month. If it's helpful, mark your calendar. After you've spoken with a friend, note on your calendar the day you spoke to them. Next month, when you feel like it's been forever since you spoke to that person, you'll know immediately how long ago it actually was.<br />
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<span style="background-color: #6fa8dc;"> <span style="background-color: #cfe2f3;"><span style="background-color: #6fa8dc;"> </span> </span></span><span style="background-color: #cfe2f3;"><b>Remember birthdays</b> </span><br />
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<span style="font-size: large;"><span class="fullpost"> Keep track of your close friends' birthdays, and commit to at least sending them a birthday card, if not an actual birthday phone call. Even better: send flowers or a surprise through the mail.<br />
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<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> <b>Update your address book</b> </span><br />
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Update your address book with current addresses and phone numbers regularly. When it comes time to make calls or send out holiday cards, you'll be able to immediately reach your friends.<br />
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<span style="font-size: large;"><span class="fullpost"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> <b>Email or chat online</b> </span><br />
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Take advantage of e-mail. Quick and accessible, e-mail is a great way to send a quick note to a friend. In addition, it's a wonderful way to make lunch plans or get the details of an upcoming weekend trip.<br />
Make sure you both have e-mail addresses, and you're all set! Homemade letters can easily get lost on the way, get torn, or just get boring. E-mailing your pals is a great and helpful way to stay in touch with each other. Use instant messengers such as MSN or AIM to your advantage, by talking to all your pals at once! Whenever you switch on the computer, be sure to check your in-box of updates!<br />
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<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> </span></span></span><span style="background-color: #cfe2f3; font-size: large;"><span class="fullpost"><b>Mark the moments you wish you could be there</b> </span></span><br />
<span style="font-size: large;"><span class="fullpost"> <br />
Mark the moments you wish you could be there for friends, even when you physically cannot. If you miss a wedding or a friend is a new parent, send a note or thoughtful gift to wish them the best.<br />
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<b>Write letters</b>. It's fun to get mail, and sometimes letters can be a great way to let your pal know what's going on with you. Not sure where to start? It's easy! Tell them how much you miss them, and then tell them all about what's going on in your life. Don't be afraid of being boring...if they know exactly what's up, they'll feel closer to you. Some people find it hard to write letters - it's a lot different than talking! Just write as though you're talking to your friend. Use phrases that you say a lot. Do you say "like" pretty much like, every second word? Then use that when you're writing! It's easy once you get going. Finish your letter off with smiley faces, drawings, x's and o's...whatever seems suitable.<br />
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<b>Send cards</b>. Hallmark cards are easily accessible, and it's a non-time-consuming way to let your bud know your thinking about them. Pick something that you think will make them laugh, or one with heartfelt sentiments that describe your friendship. Hallmark's line of musical cards - they sing when you open them! - are sure to bring a smile. Then just sign your name, add a quick message, and send it off!<br />
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<b>Send gifts</b> in the mail! Baking, books, magnets, bookmarks, jewelry, games, pictures and videos of you and your family and friends...anything goes! Sometimes the littlest things can show that you care the most - just inexpensive trinkets that show that you're thinking of your friend!<br />
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<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> </span></span></span><span style="background-color: #cfe2f3; font-size: large;"><span class="fullpost"><b>Plan annual get together</b> </span></span><br />
<span style="font-size: large;"><span class="fullpost"> <br />
Whether it's yourself and a best friends or a circle of friends who are now scattered across the country, make it a point to make regular plans for time that you can spend together. You can make it for spouses and children, if they exist, or simply have a weekend together.<br />
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<b><i>References:</i></b><br />
<a href="http://www.ehow.com/" rel="nofollow" target="_blank">ehow</a><br />
<a href="http://www.wikihow.com/" target="_blank">wikihow</a><br />
</span></span><br />
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KeepOnTouchhttp://www.blogger.com/profile/07899435487244202636noreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-44281069021725205512012-04-01T11:04:00.000-07:002012-04-01T11:08:09.585-07:00What is a Satellite?<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsxPo2quTjhkgSMVOR6iI4GAg9youDjzkSqIXzbuHlW4XsMy3xRNPkSWp2MB5LHwO5sap-sdFwgSrDW9YsuhRfov5HLMg2deTMrzeFAdp7Xvl0d7h2lH4GR0uF8JWVY4imkQvwfqd1fr90/s1600/What+is+a+Satellite.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="What is a Satellite" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsxPo2quTjhkgSMVOR6iI4GAg9youDjzkSqIXzbuHlW4XsMy3xRNPkSWp2MB5LHwO5sap-sdFwgSrDW9YsuhRfov5HLMg2deTMrzeFAdp7Xvl0d7h2lH4GR0uF8JWVY4imkQvwfqd1fr90/s1600/What+is+a+Satellite.JPG" title="What is a Satellite" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">What is a Satellite</span></b></td></tr>
</tbody></table><span style="font-size: large;">In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon.<br />
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The world's first artificial satellite, the Sputnik 1, was launched by the Soviet Union in 1957. Since then, thousands of satellites have been launched into orbit around the Earth; also some satellites, notably space stations, have been launched in parts and assembled in orbit. Artificial satellites originate from more than 50 countries and have used the satellite launching capabilities of ten nations. A few hundred satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A few space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, and the Sun.<br />
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<span class="fullpost"><br />
Satellites are used for a large number of purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.<br />
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Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control and orbit control.<br />
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<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Satellites Applications </span> <br />
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Not so long ago, satellites were exotic, top-secret devices. They were used primarily in a military capacity, for activities such as navigation and espionage. Now they are an essential part of our daily lives. We see and recognize their use in weather reports, television transmission by DIRECTV and the DISH Network, and everyday telephone calls. In many other instances, satellites play a background role that escapes our notice:<br />
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<br />
<ul><li> Some newspapers and magazines are more timely because they transmit their text and images to multiple printing sites via satellite to speed local distribution.</li>
<li> Before sending signals down the wire into our houses, cable television depends on satellites to distribute its transmissions.</li>
<li> The most reliable taxi and limousine drivers are sometimes using the satellite-based Global Positioning System (GPS) to take us to the proper destination.</li>
<li> The goods we buy often reach distributors and retailers more efficiently and safely because trucking firms track the progress of their vehicles with the same GPS. Sometimes firms will even tell their drivers that they are driving too fast.</li>
<li> Emergency radio beacons from downed aircraft and distressed ships may reach search-and-rescue teams when satellites relay the signal.</li>
</ul><br />
<i><b>References:</b></i><br />
<a href="http://en.wikipedia.org/wiki/" rel="nofollow" target="_blank">Wikipedia</a><br />
<a href="http://science.howstuffworks.com/" rel="nofollow" target="_blank">How Stuff Works </a></span><br />
</span><br />KeepOnTouchhttp://www.blogger.com/profile/07899435487244202636noreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-36163244401575256442012-03-08T09:01:00.002-08:002013-03-19T08:59:12.768-07:00FM Demodulation<br />
<br />
<span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> THE PHASE LOCKED LOOP (PLL)</span> </span><br />
<span style="font-size: large;"> </span><br />
<span style="font-size: large;">In the last section, the PLL was mentioned as a way to demodulate an FM signal. In addition to FM demodulation, PLLs are used in a wide variety of communications applications, which include TV receivers, tone decoders, telemetry receivers, modems and data synchronizers, to name a few. Many of these applications are covered in electronic communications courses. In fact, entire books have been written on the finer points of PLL operation, analysis, and applications. The approach in this section is intended only to present the basic concept and give you an intuitive idea of how PLLs work and how they are used in FM demodulation. A specific PLL integrated circuit is also introduced.<br />
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<span class="fullpost"><br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> The Basic PLL Concept </span><br />
</span></span><br />
<span style="font-size: large;"><span class="fullpost">The phase locked loop (PLL) is a feedback circuit consisting of a phase detector, a low-pas filter, and a voltage-controlled oscillator (VCO) Some PLLs also includes an amplifier in the loop. A basic block diagram is shown in figure 5.16.<br />
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</span></span><br />
<div style="text-align: center;">
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<div style="text-align: center;">
<span style="font-size: large;"><span class="fullpost"><span style="font-family: "Times New Roman","serif"; font-size: 12pt;"></span></span></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrpqUZ_2nlii1yjRg2UIBDbQ1mGvMUJvobluULNtebKS1c_pBX2wbCrLng5c_pFRyR8oJfuwl7jbaRJJDl-Rqfq3XwPf_Zy_jiskXlmehipIMNQpuG65-bl37oHRYim8RQgy9A5g4ppp06/s1600/Basic+PLL+block+diagram.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="FM Demodulation_Basic PLL block diagram" border="0" height="307" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrpqUZ_2nlii1yjRg2UIBDbQ1mGvMUJvobluULNtebKS1c_pBX2wbCrLng5c_pFRyR8oJfuwl7jbaRJJDl-Rqfq3XwPf_Zy_jiskXlmehipIMNQpuG65-bl37oHRYim8RQgy9A5g4ppp06/s400/Basic+PLL+block+diagram.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Basic PLL block diagram</b></span></td></tr>
</tbody></table>
<div style="text-align: center;">
</div>
<span style="font-size: large;"><span class="fullpost">The general operation of a PLL is as follows. The phase detector compares the phase difference between the incoming signal, Vi, and the VCO signal, Vo.<br />
<br />
When the frequency of the incoming signal, fi, is the difference from that of the VCO frequency, f<span style="font-size: x-small;">o</span>, the phase angle between the two signals is also different. The output of the phase detector and the filter is proportional to the phase difference of the two signals. This proportional voltage is fed to the VCO, forcing its frequency to move toward the frequency of the incoming signal until the two frequencies are equal. At this point, the PLL is locked onto the incoming frequency. If f<span style="font-size: x-small;">i</span> change, the phase difference also changes, forcing the VCO to track the incoming frequency.<br />
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<a href="http://keepontouch-en.blogspot.com/2011/05/references.html" target="_blank"><i>References</i></a></span></span><br />
<span style="font-size: large;"><span class="fullpost"><i> </i><br />
</span></span>KeepOnTouchhttp://www.blogger.com/profile/07899435487244202636noreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-43789544648805436152012-02-19T08:08:00.002-08:002013-03-19T09:12:07.253-07:00Mobile Tracking using the Cell ID<br />
<span style="font-size: large;">Cell ID location tracking system is a great way to know where someone is within an accuracy of about 1km but it is <b>not a substitute for GPS tracking</b> systems. The Cell ID system is only accurate enough to answer the question "Which part of town are you in" and not " Which street are you in". For the majority of users this is sufficient to prove if someone was lying about their location. </span><br />
<span class="fullpost"><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><span style="font-size: large;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKKUy1DztO01gv9R2QD0RYen15z7NaKa3CpLBwQ2vpq_tyxFU7L0J93AeQK9hGO4a2TM_-epblRflGy4XNuEpwJjdJ0ssBlIrhy0746tTsgs8BwQEZgUbGamL9kByfgXvArnlNgbSXT04/s1600/Mobile+Tracking+useing+the+Cell+ID.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Mobile Tracking using the Cell ID" border="0" height="221" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKKUy1DztO01gv9R2QD0RYen15z7NaKa3CpLBwQ2vpq_tyxFU7L0J93AeQK9hGO4a2TM_-epblRflGy4XNuEpwJjdJ0ssBlIrhy0746tTsgs8BwQEZgUbGamL9kByfgXvArnlNgbSXT04/s320/Mobile+Tracking+useing+the+Cell+ID.jpg" title="Mobile Tracking using the Cell ID" width="320" /></a></span></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Mobile Tracking using the Cell ID</b></span></td></tr>
</tbody></table><span style="font-size: large;"><br />
</span> <span style="font-size: large;"><br />
</span> <span style="background-color: #6fa8dc; font-size: large;"> </span><span style="background-color: #cfe2f3; font-size: large;"> What is Cell ID? </span><br />
<span style="font-size: large;"><br />
</span> <span style="font-size: large;">A <a href="http://keepontouch-en.blogspot.com/2011/11/gsm-architecture-and-definitions.html" target="_blank">GSM</a> <b>Cell ID</b> (CID) is a generally unique number used to identify each Base transceiver station (BTS) or sector of a BTS within a Location area code (LAC) if not within a GSM network.</span><br />
<span style="font-size: large;"><br />
</span> <span style="background-color: #6fa8dc; font-size: large;"> </span><span style="background-color: #cfe2f3; font-size: large;"> How</span><span style="background-color: #cfe2f3; font-size: large;"> Cell ID technique works? </span><br />
<span style="font-size: large;"><br />
</span> <span style="font-size: large;">A network provider has several hundred radio base stations ( cells) that make up its network. Each base station is a "cell" which covers a physical area and these cells connect together to make up the entire network. The size of cells depends on the density of base station installed in a given area. Cell sizes can vary from 100m in cities to 3K in rural areas .A mobile phone connects to the network using the cell in which it is located.. As the mobile moves, it leaves one cell and joins another. The new cell then takes responsibility for connecting the phone to the network. </span><br />
<span style="font-size: large;">Every time the cell that "owns" the mobile changes, you can get the cell id and cell name ( if available) . You can tell which cell controls the mobile by the name or by resolving the cell id against a database of cell id to locations.</span><br />
<span style="font-size: large;"><br />
</span> <span style="font-size: large;">Cell ID location tracking is based on information that is freely available from the airwaves, and the location information is the form of a CELL ID, and the name of the CELL. The name of the cell is usually the name of a part of town, and so this is good enough to know where someone is. </span><br />
<span style="font-size: large;"><br />
</span> <span style="font-size: large;"><i><b><span cstyle="font-size: large;">Source:</span></b></i> </span><br />
<span style="font-size: large;"> <a href="http://www.flexispy.com/" rel="nofollow" target="_blank">FlexiSPY</a></span><br />
<span style="font-size: large;"> <a href="http://en.wikipedia.org/wiki/" rel="nofollow" target="_blank">Wikipedia</a> </span><br />
<span style="font-size: large;"> <a href="http://www.gsm-modem.de/" rel="nofollow" target="_blank">GSM Modem</a></span></span><br />
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Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-63837707502979697872012-01-23T07:06:00.000-08:002012-01-23T07:06:18.772-08:00Stop paying PER Device for Wi-Fi access!<br />
<b><span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> It's Easy as 1,2,3!</span></span></b><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtwoe7mhPUsNlwRsr2G4PJIKM0M-_2XEhKySJu-AtN1P-6rgo0m2pKBPLC8gOTmqeqpgSpHNe9zHPhO6hV0t1lOe5IUYbArPG3HSNwgLlSD_bFVPKSXXCcDadLNfrnd0OGn-blOVzAlh0/s1600/%25D8%25A7%25D8%25AA%25D8%25B5%25D8%25A7%25D9%2584+%25D8%25A8%25D8%25A7%25D9%2584%25D8%25A5%25D9%2586%25D8%25AA%25D8%25B1%25D9%2586%25D8%25AA-%25D9%2587%25D8%25A7%25D8%25AA%25D9%2581+%25D9%2585%25D8%25AD%25D9%2585%25D9%2588%25D9%2584-%25D9%2584%25D8%25A7%25D8%25A8+%25D8%25AA%25D9%2588%25D8%25A8.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Access Internet by your Cell Phone through WiFi" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtwoe7mhPUsNlwRsr2G4PJIKM0M-_2XEhKySJu-AtN1P-6rgo0m2pKBPLC8gOTmqeqpgSpHNe9zHPhO6hV0t1lOe5IUYbArPG3HSNwgLlSD_bFVPKSXXCcDadLNfrnd0OGn-blOVzAlh0/s1600/%25D8%25A7%25D8%25AA%25D8%25B5%25D8%25A7%25D9%2584+%25D8%25A8%25D8%25A7%25D9%2584%25D8%25A5%25D9%2586%25D8%25AA%25D8%25B1%25D9%2586%25D8%25AA-%25D9%2587%25D8%25A7%25D8%25AA%25D9%2581+%25D9%2585%25D8%25AD%25D9%2585%25D9%2588%25D9%2584-%25D9%2584%25D8%25A7%25D8%25A8+%25D8%25AA%25D9%2588%25D8%25A8.JPG" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">Access Internet by your Cell Phone through WiFi</span></b></td></tr>
</tbody></table>
<b><span style="font-size: small;"><br />
</span></b><br />
<div style="text-align: left;">
<span style="font-size: large;">1: Set your desired Hotspot name and password.</span></div>
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<br /></div>
<div style="text-align: left;">
<span style="font-size: large;">2: Select which Internet connection you'd like to share.</span></div>
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<span style="font-size: large;">3:Click Start Hotspot.</span></div>
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</span><br />
<b><span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Stop paying PER Device for Wi-Fi access!</span></span></b><br />
<span style="font-size: large;"><br />
</span><br />
<span class="fullpost"><br />
<span style="font-size: large;">If you have to pay for Wi-Fi, at least make it work for you!</span><br />
<span style="font-size: large;">Create a Connectify hotspot and get all your devices online simultaneously without paying outrageous fees.</span><br />
<span style="font-size: large;"><br />
</span><br />
<span style="background-color: #6fa8dc; font-size: large;"> <span style="background-color: #cfe2f3;"> </span></span><span style="background-color: #cfe2f3; font-size: large;"> <b>Weak Wi-Fi Signal or Wired Only? </b></span><br />
<br />
<span style="font-size: large;">With Connectify you can wirelessly share the Internet connection in your room with your phone, tablet, gaming system, and other <i>equally important</i> study tools.</span><br />
<br />
<span style="font-size: large;"><a href="http://www.connectify.me/download-lite/" target="_blank">Connectify Download </a></span><br />
<br />
</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-14604537003329053252012-01-03T10:45:00.000-08:002013-03-19T09:41:58.919-07:00Code Division Multiple Access (CDMA)<br />
<span style="font-size: large;"><span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> </span></span><span style="background-color: #cfe2f3;">CDMA </span><br />
<br />
Short for Code-Division Multiple Access, a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems, such as GSM, that use TDMA, CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Individual conversations are encoded with a pseudo-random digital sequence. CDMA consistently provides better capacity for voice and data communications than other commercial mobile technologies, allowing more subscribers to connect at any given time, and it is the common platform on which 3G technologies are built.<br />
<br />
<span class="fullpost"><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQyqAwY-9YZx8RR5S0OkehRRieQ3KV0Fo-DNOFTJXwYdYCn_nLTFLzL_DSx8nIWpzY26qP4w29a8aGmsW4_CmUb6mBE0_F5fHtW6_-gTd5s-6zWzOYuRqLL-NckWpFUje0JBgiaDAwANs/s1600/Code+Division+Multiple+Access+%2528CDMA%2529.JPG" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Code Division Multiple Access (CDMA)" border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQyqAwY-9YZx8RR5S0OkehRRieQ3KV0Fo-DNOFTJXwYdYCn_nLTFLzL_DSx8nIWpzY26qP4w29a8aGmsW4_CmUb6mBE0_F5fHtW6_-gTd5s-6zWzOYuRqLL-NckWpFUje0JBgiaDAwANs/s320/Code+Division+Multiple+Access+%2528CDMA%2529.JPG" title="Code Division Multiple Access (CDMA)" width="315" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Code Division Multiple Access (CDMA)</b></span></td></tr>
</tbody></table>
<br />
CDMA users share a common frequency channel. All users are on the same frequency at the same time. However, each pair of users is assigned a special code that reduces interference while increasing privacy.<br />
<br />
<span style="background-color: #6fa8dc;"> </span> Advantages of CDMA<br />
<br />
Most efficient use of available bandwidth the foremost advantage is the large band width and its equivalent effect utilization for sending and receiving the data.<br />
<br />
<b>No separate time Access divisions</b><br />
In CDMA technology there is no time limitation slot division for using the band width and sending and receiving the data like in TDMA.<br />
<br />
<b>Power and bandwidth frequency</b><br />
Power frequency remains constant in both sending and receiving and uniform bandwidth keeps the transmission faster and in time.<br />
<br />
<b>Resource allocation</b><br />
Another advantage of CDMA is the flexible resource allocation which means that a certain kind of pin code is provide to the active users to communicate with each other. Fixed time and bandwidth keeps the simultaneous exchange of message at both sender and receivers end and specific number of packets with limited length keeps the extra traffic out of the channel.<br />
<br />
<span style="background-color: #6fa8dc;"> </span> Disadvantages of CDMA <br />
<br />
The main disadvantage of CDMA is that it can’t be used for the multi channel or multiple transmission paths. All the communication is performed over a single path. This make it fixed for singular purposes which is main drawback of CDMA technology.<br />
<br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Space Division Multiple Access (SDMA) </span><br />
<br />
Space Division Multiple Access (SDMA) - A variation of TDMA and CDMA that potentially will be used in high-bandwidth, third-generation wireless products.<br />
<br />
SDMA is a channel access method based on creating parallel spatial pipes next to higher capacity pipes through spatial multiplexing and/or diversity, by which it is able to offer superior performance in radio multiple access communication systems. In traditional mobile cellular network systems, the base station has no information on the position of the mobile units within the cell and radiates the signal in all directions within the cell in order to provide radio coverage. This results in wasting power on transmissions when there are no mobile units to reach, in addition to causing interference for adjacent cells using the same frequency, so called co-channel cells. Likewise, in reception, the antenna receives signals coming from all directions including noise and interference signals. By using smart antenna technology and differing spatial locations of mobile units within the cell, space-division multiple access techniques offer attractive performance enhancements. The radiation pattern of the base station, both in transmission and reception, is adapted to each user to obtain highest gain in the direction of that user. This is often done using phased array techniques.<br />
<br /><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;">
<span style="font-size: large;"></span>Comparison of Multiple Access Systems</span></span></span><br />
<span style="font-size: large;"><span class="fullpost"><span style="background-color: white;"> </span><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRJV1hO4eeRW1YUB2XSxStOT7Op3l7PxM_-ergfWY6cVsC2X8lLWwSxtovcY4ClHYDeU-mVnovIKtOzsoHgoToD3n51d3WYRf3p8L3xDLkCbkE9MMxQ7BMIXb0LJDGs37eVzWBMtWElnA/s1600/Comparison+of+multiple+access+systems.JPG" style="margin-left: auto; margin-right: auto;"><img alt="Comparison of Multiple Access Systems_CDMA_FDMA_TDMA" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRJV1hO4eeRW1YUB2XSxStOT7Op3l7PxM_-ergfWY6cVsC2X8lLWwSxtovcY4ClHYDeU-mVnovIKtOzsoHgoToD3n51d3WYRf3p8L3xDLkCbkE9MMxQ7BMIXb0LJDGs37eVzWBMtWElnA/s1600/Comparison+of+multiple+access+systems.JPG" title="Comparison of Multiple Access Systems_CDMA_FDMA_TDMA" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Comparison of Multiple Access Systems</b></span></td></tr>
</tbody></table>
<br />
This table summarizes some of the technical aspects of the multiple access technologies.<br />
<br />
The technology used determines the channel's capacity. TDMA triples the capacity of FDMA, but CDMA capacity can be up to seven times that of TDMA.<br />
<br />
<b><i>References:</i></b><br />
<a href="http://www.wifinotes.com/" rel="nofollow"><i><span style="color: black;"><span style="font-size: large;"></span></span></i>WiFi Notes</a><br />
<a href="http://en.wikipedia.org/" rel="nofollow">Wikipedia</a><br />
<a href="http://www.cdmauniversity.com/" rel="nofollow">CDMA University</a><br />
<a href="http://www.webopedia.com/" rel="nofollow">WEBOPEDIA</a><br /> <span style="font-size: large;"> </span>
<a href="http://electronics.howstuffworks.com/" rel="nofollow" target="_blank"><span style="font-size: large;"></span> How Stuff Works</a> <br />
<br />
<br />
</span></span>Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-13867058690896607852011-12-10T08:51:00.001-08:002011-12-17T06:36:02.977-08:00Frequency Division Multiple Access (FDMA)<br />
<span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> FDMA </span></span><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqi_nmCzYMvBEv4XBh90z8rpPk0cFv5ehAcooro50HImcDN_OFDgQqZldIaPuJFM7sUh9cSU6pRuon2Yzn4GwvrM1DYGSHRRAJax0ZvdEu7MW-ApMmxxIE452pMVZSI6ktSYM4MiJXSOo/s1600/Frequency+Division+Multiple+Access+%2528FDMA%2529.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Multiple Access Systems-Frequency Division Multiple Access (FDMA)" border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqi_nmCzYMvBEv4XBh90z8rpPk0cFv5ehAcooro50HImcDN_OFDgQqZldIaPuJFM7sUh9cSU6pRuon2Yzn4GwvrM1DYGSHRRAJax0ZvdEu7MW-ApMmxxIE452pMVZSI6ktSYM4MiJXSOo/s320/Frequency+Division+Multiple+Access+%2528FDMA%2529.JPG" width="289" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Frequency Division Multiple Access (FDMA)</b></span></td></tr>
</tbody></table><span style="font-size: large;"><br />
Frequency Division Multiple Access or FDMA is a channel access method used in multiple-access protocols as a channelization protocol. FDMA gives users an individual allocation of one or several frequency bands, or channels. It is particularly commonplace in satellite communication. FDMA, like other Multiple Access systems, coordinates access between multiple users.<br />
<span class="fullpost"><br />
Each FDMA subscriber is assigned a specific frequency channel. No one else in the same cell or a neighboring cell can use the frequency channel while it is assigned to a user. This reduces interference, but severely limits the number of users. <br />
<br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Advantage of FDMA </span><br />
<span style="font-size: large;"> </span><br />
<span style="font-size: large;">* FDMA technique doesn't need any base-control station.<br />
* Data that transfeered between each station to another during the transmission process will not be lost.<br />
* After the transmission of data,the effect ot the delay distortion will be so small and it can be ignored.<br />
* There is no need for network timing.<br />
* The channel operations in FDMA are simple.<br />
* In FDMA,the reduction of the information bit rate has a good effect on the capacity.<br />
* No need for any equalization.<br />
* Because of the transmission is continuous,there is almost no need for bits that are responsible for synchronization. <br />
* Simplicity in FDMA algorithms.<br />
<br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Disadvantages of FDMA </span></span><br />
<span style="font-size: large;"><br />
* In the FDMA technique,it is impossible for the stations to receive data from more than one transmission source.<br />
* One of most important thing in communication systems is the maximum data rate which is small and fixed for every channel in FDMA.<br />
* Because of the guard bands,the capacity of the FDMA will be decreased.<br />
* Increasing the cost of FDMA,since the band filters are narrow that can't be recognized by VLSI.<br />
* FDMA requires special filters to avoid any interference between the narrow channels.</span><br />
<span style="font-size: large;"><span class="fullpost"><br />
<br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> <a href="http://keepontouch-en.blogspot.com/2011/12/multiple-access-systems.html" target="_blank">TDMA</a> </span><br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> CDMA </span><br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> SDMA </span><br />
<br />
<i><b>Reference:</b></i><br />
<br />
* <a href="http://en.wikipedia.org/" target="_blank">Wikipedia</a><br />
* <a href="http://www.cdmauniversity.com/" target="_blank">CDMA University</a> <br />
* <a href="http://www.webopedia.com/" target="_blank">WEBOPEDIA</a> <br />
* <a href="http://electronics.howstuffworks.com/" target="_blank">How Stuff Works</a> </span></span><br />
<br />
<span style="font-size: medium;"><span style="font-size: medium;"> </span></span></span></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-21766732310693552792011-12-09T12:06:00.001-08:002013-03-19T09:47:56.345-07:00Multiple Access Systems<span style="font-size: large;"><b><span style="background-color: #6fa8dc;"><br />
</span></b></span><br />
<span style="font-size: large;"><b><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Why Multiple Access? </span></b><br />
</span><br />
<span style="font-size: large;">Multiple Access systems coordinates access between multiple users.Wireless telecommunications has dramatically increased in popularity, resulting in the need for technologies that allow multiple users to share the same Bandwidth.</span><br />
<span style="font-size: large;"> The following Multiple Access Systems have very different approaches to the bandwidth problem. </span><br />
<br />
<span class="fullpost"><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjx8lk06xG-yp6TIPhWn-ji4UWDU8ILa2bEBUKMbOIbEd8ngGi1cjlCAsv52Yabk8oUSlWnXMRPOCktG4d_MyvbLkOBSwWfsvDNK22nrdV9pgb6D0t3N1pfn0RPhXBhkfydWRplHpzt1bE/s1600/Time+Division+Multiple+Access+%2528TDMA%2529.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Multiple Access Systems-Time Division Multiple Access (TDMA)" border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjx8lk06xG-yp6TIPhWn-ji4UWDU8ILa2bEBUKMbOIbEd8ngGi1cjlCAsv52Yabk8oUSlWnXMRPOCktG4d_MyvbLkOBSwWfsvDNK22nrdV9pgb6D0t3N1pfn0RPhXBhkfydWRplHpzt1bE/s320/Time+Division+Multiple+Access+%2528TDMA%2529.JPG" title="Multiple Access Systems-Time Division Multiple Access (TDMA)" width="307" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Time Division Multiple Access (TDMA)</b></span></td></tr>
</tbody></table><br />
<span style="background-color: #6fa8dc; font-size: large;"> </span><span style="background-color: #cfe2f3; font-size: large;"> </span><span style="font-size: large;"><b style="background-color: #cfe2f3;">TDMA </b></span><br />
<br />
<span style="font-size: large;">Short for Time Division Multiple Access, a technology for delivering digital wireless service using time-division multiplexing (TDM). TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels. <br />
The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same transmission medium (e.g. radio frequency channel) while using only a part of its channel capacity. TDMA is used in the digital 2G cellular systems such as Global System for Mobile Communications (GSM), IS-136, Personal Digital Cellular (PDC) and iDEN, and in the Digital Enhanced Cordless Telecommunications (DECT) standard for portable phones. It is also used extensively in satellite systems, combat-net radio systems, and PON networks for upstream traffic from premises to the operator.<br />
TDMA is a type of Time-division multiplexing, with the special point that instead of having one transmitter connected to one receiver, there are multiple transmitters. In the case of the uplink from a mobile phone to a base station this becomes particularly difficult because the mobile phone can move around and vary the timing advance required to make its transmission match the gap in transmission from its peers.<br />
</span><br />
<span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Advantages of TDMA </span></span><br />
<span style="font-size: large;"><br />
The radio part of the mobile only needs to listen and broadcast for its own time slot. For the rest of the time, the mobile can carry out measurements on the network, detecting surrounding transmitters on different frequencies. This allows safe inter frequency handovers, something which is difficult in CDMA systems, not supported at all in IS-95 and supported through complex system additions in Universal Mobile Telecommunications System (UMTS). This in turn allows for co-existence of microcell layers with macrocell layers.<br />
<br />
<br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Disadvantages of TDMA </span><br />
<span style="font-size: large;"><br />
TDMA systems create interference at a frequency which is directly connected to the time slot length. This is the buzz which can sometimes be heard if a TDMA phone is left next to a radio or speakers.Another disadvantage is that the "dead time" between time slots limits the potential bandwidth of a TDMA channel. These are implemented in part because of the difficulty in ensuring that different terminals transmit at exactly the times required. Handsets that are moving will need to constantly adjust their timings to ensure their transmission is received at precisely the right time, because as they move further from the base station, their signal will take longer to arrive. This also means that the major TDMA systems have hard limits on cell sizes in terms of range, though in practice the power levels required to receive and transmit over distances greater than the supported range would be mostly impractical anyway.</span></span><br />
<span style="font-size: large;"><br />
</span><br />
<span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> <a href="http://keepontouch-en.blogspot.com/2011/12/frequency-division-multiple-access-fdma.html" target="_blank">FDMA</a> </span></span><br />
<span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> CDMA </span></span><br />
<span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> SDMA </span><br />
<br />
<i><b><span style="font-size: large;">Reference:</span></b></i><br />
<span style="font-size: large;"> </span><br />
<span style="font-size: large;"> * <a href="http://en.wikipedia.org/" target="_blank">Wikipedia</a> </span><br />
<span style="font-size: large;"> * <a href="http://www.cdmauniversity.com/" target="_blank">CDMA University</a> <br />
* <a href="http://www.webopedia.com/" target="_blank">WEBOPEDIA</a> <br />
* <a href="http://electronics.howstuffworks.com/" target="_blank">How Stuff Works</a></span><br />
<br />
</span><br />
</span>Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-11226445573778843322011-11-18T11:12:00.001-08:002013-03-19T10:03:36.940-07:00Cell Phone Network Coverage<br />
<br />
<b><span style="font-size: large;">Network coverage</span></b><br />
<br />
<span style="font-size: large;">A key part of any mobile phone specification is its operating frequency bands. The supported frequency bands determine<br />
whether a certain handset is compatible with a certain network carrier.<br />
<br />
<span class="fullpost"><br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxI5GcZfCfrpdubm9vk1lzG4RVMxLMMi60DLqYudIt4psskRxEYlhSC_YJg3GTcipdH6Pybz3DYsjmmJYxQuIKitMQ7zURqTxRMi6ZXOY_OfrrckCDcUtq_8PcHYHJQc4wbrtVL5IO4MI/s1600/Cell+Phone+Network+Coverage.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Cell Phone Network Coverage,GSM,2G,3G" border="0" height="201" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxI5GcZfCfrpdubm9vk1lzG4RVMxLMMi60DLqYudIt4psskRxEYlhSC_YJg3GTcipdH6Pybz3DYsjmmJYxQuIKitMQ7zURqTxRMi6ZXOY_OfrrckCDcUtq_8PcHYHJQc4wbrtVL5IO4MI/s400/Cell+Phone+Network+Coverage.JPG" title="Cell Phone Network Coverage,GSM,2G,3G" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Cell Phone Network Coverage</b></span></td></tr>
</tbody></table>Beside the mobile phone specifications, GSM Arena is happy to also provide you with its own country-based frequency band directory. It's not operator-specific and it's helpful if you are choosing a handset to use in your home country or if you are making sure your phone will work in the country you are heading to.<br />
You select the country you are interested in - as an example i selected Egypt - : <br />
<br />
<b>EGYPT</b><br />
<br />
<span style="color: white;"><b style="background-color: #6fa8dc;"><span style="font-size: small;">GSM 850 GSM 900 GSM 1800 GSM 1900 UMTS 850 UMTS 1900 UMTS 2100</span></b></span><br />
<span style="font-size: small;"><span style="background-color: #cfe2f3;"> </span></span><b style="background-color: #cfe2f3;"><span style="font-size: small;">No Yes Yes No No No Yes </span></b> <br />
<br />
<br />
Making calls, sending text messages and using GPRS/EDGE mobile data connection in the country of your choice requires a mobile phone that supports at least the frequency band filled as “Required” below.<br />
<br />
<b>2G capabilities</b><br />
<br />
<span style="background-color: #6fa8dc; color: #990000;">Required </span><span style="background-color: #cfe2f3;"> GSM 900</span><br />
<span style="background-color: #6fa8dc; color: #990000;">Recommended </span><span style="background-color: #cfe2f3;"> GSM 900 and GSM 1800</span><br />
<br />
Making video calls and using a high-speed 3G data connection in the country of your choice, requires a mobile phone that supports at least the frequency band filled as “Required” below .<br />
<br />
<b>3G capabilities</b><br />
<br />
<span style="background-color: #6fa8dc; color: #990000;">Required </span><span style="background-color: #cfe2f3;"> UMTS 2100</span><br />
<br />
<br />
<i>Make note that for complete accuracy you should always check with your home service provider or with the local service providers in the country you are staying at. </i><br />
<br />
<span style="font-size: large;">Check Network Coverage for your Country <a href="http://www.gsmarena.com/network-bands.php3" target="_blank">GSM Arena - Network Bands</a></span><br />
<br />
<b><i>Source:</i></b><br />
* <a href="http://www.gsmarena.com/" target="_blank">GSM Arena</a></span></span><br />
<br />
<br />
<br />
Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-15291090762908632282011-11-12T12:13:00.001-08:002013-03-19T10:49:21.089-07:00GSM Architecture and Definitions (3)<br />
<span style="font-size: large;"><b><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> The Operation and Support System</span></b> </span><br />
<br />
<span style="font-size: large;">The operations and maintenance center (OMC) is connected to all equipment in the switching system and to the BSC. The implementation of OMC is called the operation and support system (OSS). The OSS is the functional entity from which the network operator monitors and controls the system. The purpose of OSS is to offer the customer cost-effective support for centralized, regional, and local operational and maintenance activities that are required for a GSM network. An important function of OSS is to provide a network overview and support the maintenance activities of different operation and maintenance organizations. <b></b></span><br />
<br />
<span class="fullpost"><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEE2ejONQAcVZMzL1epMeNHWPAwVs9n65igt-WZxpVO5YJvjaGws0LzAxzdNAr585-7UvOEVYQjdsQltOrqypfzqC7gA5WUOIX7WeJg83P454t8UxRkxKqm1FR1QR3QHwYrS9qrWmRVNU/s1600/GSM+Operation+and+Maintenance.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="GSM Operation and Support System (OSS)" border="0" height="310" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEE2ejONQAcVZMzL1epMeNHWPAwVs9n65igt-WZxpVO5YJvjaGws0LzAxzdNAr585-7UvOEVYQjdsQltOrqypfzqC7gA5WUOIX7WeJg83P454t8UxRkxKqm1FR1QR3QHwYrS9qrWmRVNU/s400/GSM+Operation+and+Maintenance.JPG" title="GSM Operation and Support System (OSS)" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>GSM Operation and Support System (OSS)</b></span></td></tr>
</tbody></table>
<span style="font-size: large;"><b>OSS:</b> The operations and maintenance center (OMC) is connected to all equipment in the switching system and to the BSC. The implementation of OMC is called the operation and support system (OSS).<br />
Here are some of the OMC functions:<br />
* Administration and commercial operation (subscription, end terminals, charging and statistics).<br />
* Security Management.<br />
* Network configuration, Operation and Performance Management.</span><br />
<span style="font-size: large;"> * Maintenance Tasks.</span><span style="font-size: large;"> </span><br />
<span style="font-size: large;"><span class="fullpost"> </span></span><br />
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<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">GSM Architecture and Definitions</span></b></td></tr>
</tbody></table>
</span><br />
<div style="text-align: center;">
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<span style="font-size: large;"><span class="fullpost"> <br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtck-on5FXM7QAbIOlGqUp16LHb5nTqt0a6eTURFrbGYFZwRpwfM-7zFE0iMhooS6sW7XPFg_OJsqtMC91ziuQbaVVDIxwAOVK3NJZKHQNcRdYxX-TaWdTY1DKf7rDI1WJlQBp9qEm9zY/s1600/GPRS.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="GPRS (General Packet Radio Services" border="0" height="212" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtck-on5FXM7QAbIOlGqUp16LHb5nTqt0a6eTURFrbGYFZwRpwfM-7zFE0iMhooS6sW7XPFg_OJsqtMC91ziuQbaVVDIxwAOVK3NJZKHQNcRdYxX-TaWdTY1DKf7rDI1WJlQBp9qEm9zY/s400/GPRS.JPG" title="GPRS (General Packet Radio Services" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b><span class="st">GPRS (General Packet Radio Services)</span></b></span></td></tr>
</tbody></table>
<span style="background-color: #6fa8dc;"><span style="font-size: large;"><br />
<span style="background-color: #6fa8dc;"><span style="font-size: large;"> </span></span></span></span><span style="font-size: large;"><span style="background-color: #cfe2f3;"> <b>GPRS</b> General Packet Radio Services</span></span><br />
<br />
<span style="font-size: large;"><span style="font-size: large;">GPRS is a data network that overlays a second-generation GSM network. This data overlay network provides packet data transport at rates from 9.6 to 171 kbps. Additionally, multiple users can share the same air-interface resources simultaneously.<br />
<br />
GPRS attempts to reuse the existing GSM network elements as much as possible, but to effectively build a packet-based mobile cellular network, some new network elements, interfaces, and protocols for handling packet traffic are required. <b><br />
</b></span></span><br />
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<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">GSM Architecture and Definitions</span></b></td></tr>
</tbody></table>
<br />
<br />
<span style="font-size: large;"><i><b>External Networks</b></i><br />
<b>PSTN:</b> Public Switched Telephone Network<br />
<b>ISDN:</b> Integrated Services Digital Network<br />
<b>PDN:</b> Packet Data Network<br />
<br />
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</span>Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-27956077878831530332011-11-12T12:00:00.001-08:002013-03-19T10:53:55.472-07:00GSM Architecture and Definitions (2)<br />
<span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> <b>The Network Switching System</b></span><b> </b><br />
</span><br />
<span style="font-size: large;">The Network switching system (NSS) is responsible for performing call processing and subscriber-related functions. The switching system includes the following functional units. <b></b></span><br />
<br />
<span class="fullpost"><br />
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>GSM Architecture and Definitions </b></span></td></tr>
</tbody></table>
<span style="font-size: large;"><b>MSC:</b> Mobile Switching Center a switching exchange whose main functions are:<br />
– Call Handling<br />
– Specific GSM functions such as:<br />
• Mobility Management: Communication with the Location Databases (VLR<br />
and HLR)<br />
• Handover execution when involved<br />
– Gateway Function for Terminating Call (TC)<br />
<b>VLR:</b> Visitor Location Register is associated with one or more MSC. It is a local database with the following<br />
information:<br />
– Copy of the HLR data for visiting subscribers<br />
– More precise location of the Mobile Station (an area of the network called<br />
“Location Area” which is a group of cells</span><br />
<span style="font-size: large;"> – Call re-direction data</span><br />
<br />
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<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">GSM Architecture and Definition<span style="font-size: small;">s</span></span></b></td></tr>
</tbody></table>
<br />
<span style="font-size: large;"><a href="http://keepontouch-en.blogspot.com/2011/11/gsm-architecture-and-definitions_7700.html" target="_blank"><i>Next</i></a></span><span style="font-size: large;"> <i><b> </b></i></span></span><br />
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<span class="fullpost"><span style="font-size: large;"> * <a href="http://www.privateline.com/" target="_blank">Private Line</a> </span></span><br />
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</span> Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-82008831503764904362011-11-12T10:36:00.001-08:002013-03-19T11:05:54.933-07:00GSM Architecture and Definitions (1)<br />
<br />
<span style="font-size: large;"><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> What is GSM? </span><br />
<br />
GSM, which stands for <b>G</b>lobal <b>S</b>ystem for <b>M</b>obile communications, reigns as the world’s most widely used cell phone technology. Cell phones use a cell phone service carrier’s GSM network by searching for cell phone towers in the nearby area.<br />
<br />
The origins of GSM can be traced back to 1982 when the Groupe Spécial Mobile (GSM) was created by the European Conference of Postal and Telecommunications Administrations (CEPT) for the purpose of designing a pan-European mobile technology.<br />
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It is approximated that 80 percent of the world uses GSM<br />
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>GSM Architecture and Definitions</b></span></td></tr>
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technology when placing wireless calls, according to the GSM <br />
Association (GSMA), which represents the interests of the worldwide mobile communications industry. This amounts to nearly 3 billion global people.<br />
<br />
<span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> GSM </span><span style="background-color: #cfe2f3; font-size: large;">Network Structure </span><br />
<br />
The network is structured into a number of discrete sections:<br />
<br />
* The Base Station Subsystem (the base stations and their controllers).<br />
* The Network and Switching Subsystem (the part of the network most similar to a fixed network). This is sometimes also just called the core network.<br />
* The GPRS Core Network (the optional part which allows packet based Internet connections).<br />
* The Operations support system (OSS) for maintenance of the network.<b><br />
</b><br />
Now,We will explain the meaning of the GSM Network shortcuts.<br />
<br />
<b>PLMN:</b> Public Land Mobile Network is area covered by one network operator. A PLMN can contain one or more MSCs.<br />
<b>GSM:</b> Global System for Mobile communication<br />
<b>MS:</b> Mobile Station is used by the subscriber for calling another subscriber either in the fixed network or in the mobile network.A Mobile Station (MS) is composed of a Mobile Termination (MT) and a Subscriber Module Identity (SIM) card.<br />
<b>MT:</b> Mobile Termination.The MT performs the following functions:<br />
- radio transmission termination;<br />
- radio transmission channel management;<br />
- terminal capabilities, including presentation of a man-machine interface to a user;<br />
- speech encoding/decoding;<br />
- error protection for all information sent across the radio path;<br />
- flow control of signalling and user data;<br />
- rate adaptation of user data between the radio channel rate and user rates;<br />
- multiple terminal support;<br />
- mobility management. <br />
<br />
<b>SIM:</b> SIM card stores information concerning the subscriber such as subscriber identity,services subscribed, parameters for security procedures and information on the location of the subscriber (dynamically refreshed according to its movements).<br />
<u><b>Um</b></u> > The Radio Interface between MS and Base Station.<br />
<b>UpLink:</b> The Path of the Data from MS to Base Station.<br />
<b>DownLink:</b> The Path of the Data from Base Station to MS.<br />
<br />
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>GSM Architecture and Definitions</b></span></td></tr>
</tbody></table>
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<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">GSM Architecture and Definitions</span></b></td></tr>
</tbody></table>
<br />
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<br />Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-66792686856945597162011-10-19T17:19:00.000-07:002013-03-19T11:23:12.639-07:00Optical Fiber Communication<br />
<span style="font-size: large;">An optical fiber is a flexible, transparent fiber made of very pure glass (silica) not much wider than a human hair that acts as a waveguide, or "light pipe", to transmit light between the two ends of the fiber.The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.<br />
<span class="fullpost"><br />
Optical fibers are widely used in fiber-optic communications, which <br />
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Optical Fiber Communication</b></span></td></tr>
</tbody></table>
permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. Fibers are also used for illumination, and are wrapped in bundles so they can be used to carry images, thus allowing viewing in tight spaces. Specially designed fibers are used for a variety of other applications, including sensors and fiber lasers.<br />
<br />
<b><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> Optical Fiber Communication </span></b><br />
<br />
Optical fiber can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows long distances to be spanned with few repeaters. Additionally, the per-channel light signals propagating in the fiber have been modulated at rates as high as 111 gigabits per second by NTT,although 10 or 40 Gbit/s is typical in deployed systems.<br />
<br />
Each fiber can carry many independent channels, each using a different wavelength of light (wavelength-division multiplexing (WDM)). The net data rate (data rate without overhead bytes) per fiber is the per-channel data rate reduced by the FEC overhead, multiplied by the number of channels (usually up to eighty in commercial dense WDM systems as of 2008[update]).<br />
<br />
The current laboratory fiber optic data rate record, held by Bell Labs in Villarceaux, France, is multiplexing 155 channels, each carrying 100 Gbit/s over a 7000 km fiber. Nippon Telegraph and Telephone Corporation have also managed 69.1 Tbit/s over a single 240 km fiber (multiplexing 432 channels, equating to 171 Gbit/s per channel).Bell Labs also broke a 100 Petabit per second kilometer barrier (15.5 Tbit/s over a single 7000 km fiber).<br />
<br />
For short distance applications, such as a network in an office building, fiber-optic cabling can save space in cable ducts. This is because a single fiber can carry much more data than electrical cables such as standard category 5 Ethernet cabling, which typically runs at 1 Gbit/s. Fiber is also immune to electrical interference; there is no cross-talk between signals in different cables, and no pickup of environmental noise.<br />
<br />
Non-armored fiber cables do not conduct electricity, which makes fiber a good solution for protecting communications equipment in high voltage environments, such as power generation facilities, or metal communication structures prone to lightning strikes. They can also be used in environments where explosive fumes are present, without danger of ignition. Wiretapping (in this case, fiber tapping) is more difficult compared to electrical connections, and there are concentric dual core fibers that are said to be tap-proof.<br />
<br />
<b><span style="background-color: #6fa8dc;"> <span style="background-color: #cfe2f3;"> Real Project </span></span></b><br />
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</span></span><br />
<div class="separator" style="clear: both; text-align: center;">
<span style="font-size: large;"><span class="fullpost"><span style="font-size: large;"><iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.youtube.com/embed/aRKYjnBDxUg?feature=player_embedded' frameborder='0'></iframe></span></span></span></div>
<span style="font-size: large;"><span class="fullpost"><span style="font-size: large;"> </span> <div style="text-align: left;">
<span style="font-size: large;"><b> </b><i> </i></span> <span style="font-size: large;"><i>References:</i></span></div>
<div style="text-align: left;">
<span style="font-size: large;"><b> * </b><a href="http://en.wikipedia.org/">Wikipedia</a> </span></div>
<div style="text-align: left;">
<span style="font-size: large;"><b> * </b>Youtube (<a href="http://www.youtube.com/watch?v=aRKYjnBDxUg&feature=related">Make Magazine</a> Channel) </span><br />
<br />
</div>
</span> </span> Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-61573635986332485532011-09-25T12:30:00.000-07:002012-01-08T08:26:21.542-08:00Which Screen Protector should i use?<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg13J9UMrVPBPIf8tjAfYTOx8uBo2V197BBRZBPTGWtQrDTlmjw6T2Q7VzpfJsTB6rFs2y5biTg-_UZWHpvKjJj69izEXxb8dDseZidIwfu743gyzneZYmDCcwyVuaucIuAZ_QyM0dPKRs/s1600/Screen+Protector.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Best Screen Protector" border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg13J9UMrVPBPIf8tjAfYTOx8uBo2V197BBRZBPTGWtQrDTlmjw6T2Q7VzpfJsTB6rFs2y5biTg-_UZWHpvKjJj69izEXxb8dDseZidIwfu743gyzneZYmDCcwyVuaucIuAZ_QyM0dPKRs/s320/Screen+Protector.JPG" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Screen Protector</b></span></td></tr>
</tbody></table>
<br />
<span style="font-size: large;">A screen protector is used to protect the LCD screens of digital, electronic devices. The personal digital assistant (PDA) is, perhaps, the most commonly used gadget for which screen protectors are used since PDAs are operated via a stylus. If not used carefully, the tip of the stylus can potentially mar or scratch the sensitive LCD screen surface, and so screen protectors were brought to market.<br />
<br />
<span class="fullpost"><br />
The "first generation" of screen protectors were made from very thin films based on the concept that an extra layer between the two surfaces (screen and stylus) would provide the needed protection to prolong the life of the device. These screen protectors came (and still come) in packs of 10 to 20 protectors and are hand-cut by the end consumer to fit the specific device. Such screen protectors, while offering extra protection, did not completely fill the need in the marketplace. They peeled up easily and they scratched almost as easily as the screens, causing the protector to be replaced often.<br />
<br />
The newest generation of screen protectors are made from a much more durable film and are designed to be a more permanent part of the gadget which they protect. The material is a urethane-based film which is a little thicker than traditional screen protectors (.008 inches compared to .005 or .003),[citation needed] but the film is hardly noticeable once installed. The film originated when the U.S. military was looking for a way to protect the leading edges of their military helicopter blades from abrasive airborne particles (sand) while traveling at hundreds of miles per hour. The negative is that it is hard to remove and leaves a sticky residue. It is also made in small sizes, not recommended for bigger than four inch diagonal screens. Since the film is clear, there are problems with UV rays emanating from the display to the eyes and bounce back from the sun. It also does not provide protection from glare and hard to read outdoors.<br />
<br />
And for the usage of the cell phone screen, there are mainly 7 kinds of screen protector:<br />
<br />
<b style="background-color: #6fa8dc;"><span style="background-color: #9fc5e8;"><span style="background-color: #3d85c6;"><span style="background-color: #6fa8dc; color: #e06666;"><span style="font-size: x-large;"> </span></span><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;"> </span></span><span style="background-color: #cfe2f3; color: #674ea7;"><span style="color: #351c75;">Privacy Screen Protector</span> </span><span style="background-color: #cfe2f3;"> </span></span> </b><br />
As its name suggests, it is used to give users protection while they use their gadgets. When viewed from a particular angle, the privacy protector darkens your screen. It is also able to offer scratch protection if your device is touchscreen. It is the thickest screen protector available which is why it is considered to be the best type to give you protection and to keep your gadget from getting scratched. Privacy screen protectors comes in pair and can be quite expensive but if you are intent on using these, it will be worth buying.<br />
<b> </b><br /><span style="background-color: #6fa8dc;"> <span style="background-color: #cfe2f3;">
</span></span><b style="background-color: #cfe2f3;">Mirror Screen Protector </b><br />
Mirror Screen Protector is a mirror that prevents your LCD screen from getting scratched. Mirror Screen Protector looks and works like a mirror when your phone's screen is shut off (locked). Once the screen is activated, screen contents appear like normal. Mirror Screen Protector measures 85 x 70 mm (3.35 x 2.76 in.) - cut to fit your screen. One sheet can cover more than one screen depending on size of your screens. Mirror Screen Protector does not interfere with stylus or touch screen operation. Easy to apply with no bubbles and easily removable without leaving residue.<br />
<br /><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;">
</span><b style="background-color: #cfe2f3;">Matte Screen Protector </b><br />
ViewGuard Anti-Glare Matte Screen Protectors are composed of multiple layers of material, each of which helps to either reduce reflected light or provide additional impact protection for your screen. The anti-scratch coating layer protects your screen from fingerprints, smudges, and scratches. This layer also helps make the ViewGuard screen protector ideal for use with touch-screen tablet PCs and Ultra-Mobile PCs (UMPC). Honestly, who wants to clean fingerprints off a glossy screen all the time?<br />
One of the best features of the ViewGuard Anti-Glare Matte Screen Protectors is the easy on/off application. The protector is easily attached and removed time and time again without damage to your screen. The screen protector attaches directly to the surface of your display with a silicone adhesive. Since the entire multi-layer film is less than one millimeter thick it can stay attached to your screen and still allow your laptop lid to close.<br />
<b> </b><br /><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;">
</span><b style="background-color: #cfe2f3;">Ultra-Clear Screen Protector </b><br />
More or less,the screen protector will reduce the clearance of the screen. In order to get the best visual effect, the ultra-clear screen protector come out. And high transparency up to 95%.<br />
Features:<br />
1. Anti-scratch,anti-grease and dust and stain-proof.<br />
2. No-glue , static electricity self-adhesive.<br />
3. No bubble,washable and reusable.<br />
4. Long lasting protection and firmly on screen<br />
5. Leave with no residue and would not corrode the surface.<br />
6. Easy installation .Stability adhesion performance, excellent high or low temperature resistance<br />
7. Standard packing:Color card package,PE bag,cleaning cloth,soft card. Customer package available<br />
<b> </b><br /><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;">
</span><b style="background-color: #cfe2f3;">Grid Screen Protector </b><br />
If the use need the screen protector looks threads,the grid screen protetor is good choose.<br />
Features:<br />
1. Anti-scratch,anti-grease and dust and stain-proof.<br />
2. No-glue , static electricity self-adhesive.<br />
3. No bubble,washable and reusable.<br />
4. Long lasting protection and firmly on screen<br />
5. Leave with no residue and would not corrode the surface.<br />
6. Easy installation .Stability adhesion performance, excellent high or low temperature resistance<br />
7. Standard packing:Color card package,PE bag,cleaning cloth,soft card. Customer package available<br />
<b> </b><br /><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;">
</span><b style="background-color: #cfe2f3;">Diamond Screen Protector </b><br />
this kind of screen protector can show colorfull shine<br />
Features:<br />
1. Anti-scratch,anti-grease and dust and stain-proof.<br />
2. No-glue , static electricity self-adhesive.<br />
3. No bubble,washable and reusable.<br />
4. Long lasting protection and firmly on screen<br />
5. Leave with no residue and would not corrode the surface.<br />
6. Easy installation .Stability adhesion performance, excellent high or low temperature resistance<br />
7. Standard packing:Color card package,PE bag,cleaning cloth,soft card. Customer package available<br />
<b> </b><br /><span style="background-color: #6fa8dc;"> </span><span style="background-color: #cfe2f3;">
</span><b style="background-color: #cfe2f3;">3D Screen Protector </b><br />
The HTC Evo 3D Screen Protector -As an example- is the clear choice for maximum scratch protection. The HTC Evo 3D Screen Protector goes beyond your traditional HTC Evo 3D screen protectors, skins, covers, and cases. TechSkin is made from the same film material used to protect luxury cars, military aircrafts, and NASA space shuttles. The HTC Evo 3D Screen Protector is custom made to specifically fit the HTC Evo 3D .<br />
Features:<br />
* • Toughest clear protective film in the market<br />
* • Clear protection that is virtually invisible<br />
* • Preserves your HTC Evo 3D 's original design<br />
* • Protects your HTC Evo 3D from scratches, dents, and physical wear-and-tear<br />
* • Patented layer of UV protection for anti-yellowing<br />
* • Provides protection without affecting the functions of your HTC Evo 3D<br />
* • Non-sticky or restrictive outer surface</span><br />
<br />
</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-65895440612140708142011-09-16T11:04:00.000-07:002012-01-08T08:27:40.471-08:00All About iPhone 4<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcTsFRzGZjX3_JgtNywBsRlJDchZw2I7H8PWFCGL4-aNqlsQ2aTLzAcu9jrLKrQ0kVFIgI2L2w5wK2qHJuBt0np38QxBS5CWIl1R7G4am81FRqVMUZBafg-aCned2aD7yI0oayEV9zVV8/s1600/iphone+4.jpeg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="iphone 4" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcTsFRzGZjX3_JgtNywBsRlJDchZw2I7H8PWFCGL4-aNqlsQ2aTLzAcu9jrLKrQ0kVFIgI2L2w5wK2qHJuBt0np38QxBS5CWIl1R7G4am81FRqVMUZBafg-aCned2aD7yI0oayEV9zVV8/s1600/iphone+4.jpeg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>iPhone 4</b></span></td></tr>
</tbody></table>
<br />
<span style="font-size: large;">While everyone else was busy trying to keep up with iPhone, we were busy creating amazing new features that make iPhone more powerful, easier to use, and more indispensable than ever. The result is iPhone 4. The biggest thing to happen to iPhone since iPhone.</span><br />
<span class="fullpost"><br />
<b><span style="font-size: large;">Facetime</span></b><br />
<span style="font-size: large;">People have been dreaming about video calling for decades. iPhone 4 makes it a reality. With just a tap, you can wave hello to your kids, share a smile from across the globe, or watch your best friend laugh at your stories — iPhone 4 to iPhone 4 or to the new iPod touch over Wi-Fi. And it works right out of the box. No other phone makes staying in touch this much fun.</span><br />
<br />
<b><span style="font-size: large;">Two cameras,two views.</span></b><br />
<span style="font-size: large;">iPhone 4 has two cameras: One on the front, which focuses on you. And one on the back, which focuses on everything else. FaceTime lets you switch back and forth between them at any time during a video call. All you have to do is tap a button.</span><br />
<br />
<b><span style="font-size: large;">Retina Display</span></b><br />
<span style="font-size: large;">The Retina display on iPhone 4 is the sharpest, most vibrant, highest-resolution phone screen ever, with four times the pixel count of previous iPhone models. In fact, the pixel density is so high that the human eye is unable to distinguish individual pixels. Which makes text amazingly crisp and images stunningly sharp.</span><br />
<br />
<b><span style="font-size: large;">Multitasking</span></b><br />
<span style="font-size: large;">iPhone 4 introduces a whole new way of multitasking. Now you can run your favorite third-party apps — and switch between them instantly — without slowing down the performance of the foreground app or draining the battery unnecessarily.1 This smarter approach to multitasking is available only in iOS 4.</span><br />
<br />
<b><span style="font-size: large;">HD Video Recording and Editing</span></b><br />
<span style="font-size: large;">Shoot your own movies in high definition. Capture impressive video even in low-light settings, thanks to the advanced backside illumination sensor and built-in LED light. Then edit and create your own mini-masterpiece right on iPhone 4 using the iMovie app — with Apple-designed themes, titles, and transitions. It’s available on the App Store for $4.99.</span><br />
<br />
<b><span style="font-size: large;">5-Megapixel Camera with LED Flash</span></b><br />
<span style="font-size: large;">Take beautiful, detailed photos using the 5-megapixel camera with built-in LED flash. The advanced backside illumination sensor captures great pictures even in low light. And the front-facing camera makes it easy to take self-portraits.</span><br />
<br />
<iframe allowfullscreen="" frameborder="0" height="315" src="http://www.youtube.com/embed/DxcJevPVvQQ" width="560"></iframe><br />
<span style="font-size: large;"><br />
</span><br />
<span style="font-size: large;"><i>Reference</i>: <a href="http://www.apple.com/">Apple</a></span><br />
<span style="font-size: large;"> <a href="http://www.youtube.com/">YouTube</a></span><br />
<br />
</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-46773937077262075982011-09-14T16:19:00.000-07:002013-03-19T11:25:55.916-07:00Luxury retailer introduces solid gold phone with a $60,000 price tag<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4bLlXagbRQXm1-8BagvEKW0EYsaWh2tpRwduSkELX2FLX3lnkYW5pdi9BeTDHLgVpePGNVBpWOyBYB7DBk030_QmK2zAPExKKVLuc6fGF8y09XNL4LNEpTixM2toQU231UxMCptM6s1A/s1600/Gold+Phone.JPG" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Gold Phone" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4bLlXagbRQXm1-8BagvEKW0EYsaWh2tpRwduSkELX2FLX3lnkYW5pdi9BeTDHLgVpePGNVBpWOyBYB7DBk030_QmK2zAPExKKVLuc6fGF8y09XNL4LNEpTixM2toQU231UxMCptM6s1A/s1600/Gold+Phone.JPG" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Gold Phone</span></td></tr>
</tbody></table>
<br />
<span style="font-size: large;">Feature-rich smartphones aren't cheap, and critics of pricey mobile devices often claim that they are too expensive, despite their wide-ranging capabilities. Those people will want to look away now, as the newest device from Danish luxury retailer Aesir is sure to make their blood boil. Introducing the limited edition AE+Y phone — an 18-carat solid gold handset that can't use apps, email, or mobile internet, but still carries a ridiculous price of 42,000 euros (roughly $60,000).<br />
The lavish device boasts groundbreaking features such as speed dial, call forwarding, and even a built-in calculator. <br />
<br />
<span class="fullpost"><br />
Its LCD screen measures a modest 2", and its battery can handle a measly 5 hours of talk time — compared to the Droid Bionic's 11-hour, and iPhone 4's 14-hour limits. But Aesir is focusing more on form than function, and the manufacturer is quick to point out that the edge-to-edge key design is a first in mobile handsets.<br />
<br />
The AE+Y's barebones user interface was shaped by renowned designer Tom Hingston, and the phone's unorthodox keypad is laser-engraved and features "advanced LED backlighting." We're not quite sure how that varies from regular LED backlighting, but I guess we have to take Aesir's word on that.<br />
<br />
Aesir's target market is clearly the super rich, but do the wealthy not also desire useful gadgets? Then again, if you're affluent enough to drop $60,000 on a solid gold phone, you're probably too busy playing polo and ordering around your servants to care about apps or email anyway.<br />
<br />
For those of you who are only rich — as opposed to super rich — Aesir is also making a stainless steel version which will retail for a slightly less mind boggling $10,000. Both devices will debut this fall in Europe, and shortly thereafter in the U.S.<br />
<b> </b></span></span><br />
<span style="font-size: large;"><span class="fullpost"><i><b>Source</b></i>: <a href="http://www.yahoo.com/" rel="nofollow"><i>Yahoo</i></a> </span></span><br />
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Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-2247216174331241102011-08-30T18:56:00.000-07:002012-01-09T09:32:03.073-08:00All about ipad 2<br />
<span style="font-size: large;"><b>There‘s more to it. And even less of it.</b> </span><br />
<span style="font-size: large;"><iframe align="left" frameborder="0" marginheight="0" marginwidth="0" scrolling="no" src="http://rcm.amazon.com/e/cm?t=kee04-20&o=1&p=8&l=bpl&asins=B0047DVWLW&fc1=000000&IS2=1&lt1=_blank&m=amazon&lc1=0000FF&bc1=000000&bg1=FFFFFF&f=ifr" style="height: 245px; padding-right: 10px; padding-top: 5px; width: 131px;"></iframe>Two cameras for FaceTime and HD video recording. The dual-core A5 chip. The same 10-hour battery life.1 All in a thinner, lighter design. Now iPad is even more amazing. And even less like anything else.<br />
<b> </b><br />
<b>Thinner, lighter, and<br />
full of great ideas.</b><br />
Once you pick up iPad 2, it’ll be hard to put down.<span class="fullpost"><br />
That’s the idea behind the all-new design. It’s 33 percent thinner and up to 15 percent lighter, so it feels even more comfortable in your hands.2 And it makes surfing the web, checking email, watching movies, and reading books so natural, you might forget there’s incredible technology under your fingers.<br />
<br />
<b>Dual-core A5 chip.It’s fast, times two.</b><br />
Two powerful cores in one A5 chip mean iPad can do twice the work at once. You’ll notice the difference when you’re surfing the web, watching movies, making FaceTime video calls, gaming, and going from app to app to app. Multitasking is smoother, apps load faster, and everything just works better.<br />
<br />
<b>Superfast graphics.Go, gamers, go.</b><br />
With up to nine times the graphics performance, gameplay on iPad is even smoother and more realistic. And faster graphics help apps perform better — especially those with video. You’ll see it when you’re scrolling through your photo library, editing video with iMovie, and viewing animations in Keynote.</span></span><br />
<span style="font-size: large;"><span class="fullpost"><br />
<b>Battery life keeps on going. So you can, too.</b><br />
Even with the new thinner and lighter design, iPad has the same amazing 10-hour battery life.1 That’s enough juice for one flight across the ocean, or one movie-watching all-nighter, or a week’s commute across town. The power-efficient A5 chip and iOS keep battery life from fading away, so you can get carried away.<br />
<br />
<b>Two cameras. And a big hello to FaceTime for iPad.</b><br />
You’ll see two cameras on iPad — one on the front and one on the back. They may be tiny, but they’re a big deal. They’re designed for FaceTime video calling, and they work together so you can talk to your favorite people and see them smile and laugh back at you.3 The front camera puts you and your friend face-to-face. Switch to the back camera during your video call to share where you are, who you’re with, or what’s going on around you. When you’re not using FaceTime, let the back camera roll if you see something movie-worthy. It’s HD, so whatever you shoot is a mini-masterpiece. And you can take wacky snapshots in Photo Booth. It’s the most fun a face can have.<b><br />
<br />
iPad Smart Cover. Designed for iPad. And vice versa.<br />
</b><br />
<b>LED-backlit display.The view is amazing.<br />
<br />
Multi-Touch.Everything’s at your fingertips.<br />
<br />
iOS 4.The world’s most advanced mobile operating system.<br />
<br />
Wi-Fi and 3G.Two great ways to stay connected.<br />
</b><br />
<b>Gyro, accelerometer, and compass.<br />
iPad knows your every move.<br />
</b><br />
<b>AirPlay.Your movie-photo-music stream.<br />
<br />
Video mirroring.What you do is what they see.<br />
</b><br />
<b>AirPrint. Print everything wirelessly.</b></span><b></b><br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.youtube.com/embed/k1aKUcIU2kk?feature=player_embedded' frameborder='0'></iframe></div>
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</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-53216294379777434542011-08-28T13:59:00.000-07:002012-01-09T09:32:37.299-08:00Computing Future<br />
<span style="font-size: large;">The history of computers and computer technology thus far has been a long and a fascinating one, stretching back more than half a century to the first primitive computing machines. These machines were huge and complicated affairs, consisting of row upon row of vacuum tubes and wires, often encompassing several rooms to fit it all in.<br />
As anyone who has looked at the world of computers lately can attest, the size of computers has been reduced sharply, even as the power of these machines has increased at an exponential rate. In fact, the cost of computers has come down so much that many households now own not only one, but two, three or even more, PCs.<br />
<span class="fullpost"><br />
As the world of computers and computer technology continues to evolve and change, many people, from science fiction writers and futurists to computer workers and ordinary users, have wondered what the future holds for the computer and related technologies. Many things have been pictured, from robots in the form of household servants to computers so small they can fit in a pocket. Indeed, some of these predicted inventions have already come to pass, with the introduction of PDA's and robotic vacuum cleaners.<br />
<div style="text-align: right;">
<iframe align="left" frameborder="0" marginheight="0" marginwidth="0" scrolling="no" src="http://rcm.amazon.com/e/cm?t=kee04-20&o=1&p=8&l=bpl&asins=B0013FRNKG&fc1=000000&IS2=1&lt1=_blank&m=amazon&lc1=0000FF&bc1=000000&bg1=FFFFFF&f=ifr" style="height: 245px; padding-right: 10px; padding-top: 5px; width: 131px;"></iframe></div>
Beyond these innovations, however, there are likely to be many, many more. One of the most important areas of research in the world of computers is that of artificial intelligence. When many people think of artificial intelligence, they may picture fully aware machines, complete with emotions, and the problems that can arise from them. Even though this remains the goal of many artificial intelligence researchers, in fact artificial intelligence technology is already in place and already serving the needs of humans everywhere.<br />
By a Poll created by <a href="http://www.hothardware.com/" rel="nofollow">HotHardWare </a>about Computing Tool in the next 10 Years Handsets had 34% of 6928 Votes .</span><br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSafMEQyS6QwCqL04Pd0H89nLMYxubNfNrw9Y2VVrjyo5GU9U7TznlsaLNordG1dt2STvHjVQrqucKz3EJfKyvUwwk3VwtjTyWzejNB-NTXR0ppLfDDTnYGx1c95cSAx-WNXF-uhEDfq0/s1600/Computers+Future.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Computing Future" border="0" height="156" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSafMEQyS6QwCqL04Pd0H89nLMYxubNfNrw9Y2VVrjyo5GU9U7TznlsaLNordG1dt2STvHjVQrqucKz3EJfKyvUwwk3VwtjTyWzejNB-NTXR0ppLfDDTnYGx1c95cSAx-WNXF-uhEDfq0/s400/Computers+Future.JPG" width="400" /></a><br />
<br />
</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-16105438760530719802011-08-28T13:29:00.000-07:002012-01-09T09:33:04.262-08:00Your Choice for Social Network Dominance<br />
<span style="font-size: large;">A <b>social network</b> is a social structure made up of individuals (or organizations) called "nodes", which are tied (connected) by one or more specific types of interdependency, such as friendship, kinship, common interest, financial exchange, dislike, or relationships of beliefs, knowledge or prestige.<br />
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Social network analysis views social relationships in terms of network theory consisting of nodes and ties (also called edges, links, or connections). Nodes are the individual actors within the networks, and ties are the relationships between the actors. <br />
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The resulting graph-based structures are often very complex. There can be many kinds of ties between the nodes. Research in a number of academic fields has shown that social networks operate on many levels, from families up to the level of nations, and play a critical role in determining the way problems are solved, organizations are run, and the degree to which individuals succeed in achieving their goals.<br />
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In its simplest form, a social network is a map of specified ties, such as friendship, between the nodes being studied. The nodes to which an individual is thus connected are the social contacts of that individual. The network can also be used to measure social capital – the value that an individual gets from the social network. These concepts are often displayed in a social network diagram, where nodes are the points and ties are the lines. <br />
By a Poll created by <a href="http://www.hothardware.com/" rel="nofollow">HotHardWare </a>about Social Network Dominance Google+ had 41% of 1170 Votes .</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-hInR2DAokbEwGmgoGwEBY4ZRQIQIO4qBIzwMBSnYqjYTZnN9WY5PCLM1SYNcMIhKkT9GL7DBN0NiMsMH0otmWGEV_g1LXfk-QjdK4GlkA6GBdr58mF8cvYbi0ApYmO3BO01vD57Kx5I/s1600/Social+Network+Poll.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Social Network" border="0" height="155" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-hInR2DAokbEwGmgoGwEBY4ZRQIQIO4qBIzwMBSnYqjYTZnN9WY5PCLM1SYNcMIhKkT9GL7DBN0NiMsMH0otmWGEV_g1LXfk-QjdK4GlkA6GBdr58mF8cvYbi0ApYmO3BO01vD57Kx5I/s400/Social+Network+Poll.JPG" width="400" /></a><br />
</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-19949016053026004272011-08-19T10:50:00.000-07:002012-01-09T09:33:24.673-08:00Cell Phones (6)<br />
<span style="font-size: x-large;"><b>Along Comes Digital</b></span><br />
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<tr><td class="tr-caption" style="text-align: center;">Digital Cell Phone</td></tr>
</tbody></table><span style="font-size: large;">Digital cell phones are the second generation (2G) of cellular technology. They use the same radio technology as analog phones, but they use it in a different way. Analog systems do not fully utilize the signal between the phone and the cellular network -- analog signals cannot be compressed and manipulated as easily as a true digital signal.<br />
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This is the reason why many cable companies are switching to digital -- so they can fit more channels within a given bandwidth. It is amazing how much more efficient digital systems can be.<br />
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Digital phones convert your voice into binary information (1s and 0s) and then compress it (see How Analog-Digital Recording Works for details on the conversion process). This compression allows between three and 10 digital cell-phone calls to occupy the space of a single analog call.<br />
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Many digital cellular systems rely on frequency-shift keying (FSK) <iframe align="left" frameborder="0" marginheight="0" marginwidth="0" scrolling="no" src="http://rcm.amazon.com/e/cm?t=kee04-20&o=1&p=8&l=bpl&asins=B0036D9YKA&fc1=000000&IS2=1&lt1=_blank&m=amazon&lc1=0000FF&bc1=000000&bg1=FFFFFF&f=ifr" style="height: 245px; padding-right: 10px; padding-top: 5px; width: 131px;"></iframe>to send data back and forth over AMPS. FSK uses two frequencies, one for 1s and the other for 0s, alternating rapidly between the two to send digital information between the cell tower and the phone. Clever modulation and encoding schemes are required to convert the analog information to digital, compress it and convert it back again while maintaining an acceptable level of voice quality. All of this means that digital cell phones have to contain a lot of processing power.<br />
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Source: <a href="http://www.howstuffworks.com/" rel="nofollow">How Stuff Works </a><br />
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</span></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-4884677951645002032011-08-19T08:36:00.000-07:002013-03-19T11:29:10.905-07:00Five things you probably didn’t know could be hacked<div class="separator" style="clear: both; text-align: center;">
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<span style="font-size: large;">Hackers are making headlines these days like never before. From video game systems to voice mail accounts, it seems like almost every type of electronic device or information storage medium can be hacked to either give up information or perform actions it wasn't initially designed to do. <br />
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We've gathered a handful of the weirdest hacks out there, and the vulnerability of some of your everyday devices might surprise you.</span><br />
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<span style="font-size: large;"><b>1. Medical implants</b><br />
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High-tech medical devices like pacemakers and insulin pumps can save lives, but hackers can actually utilize their built-in wireless features for less helpful purposes. Researchers have demonstrated that certain pacemakers that use a wireless signal for easy tweaking<iframe align="left" frameborder="0" marginheight="0" marginwidth="0" scrolling="no" src="http://rcm.amazon.com/e/cm?t=kee04-20&o=1&p=8&l=bpl&asins=0801679788&fc1=000000&IS2=1&lt1=_blank&m=amazon&lc1=0000FF&bc1=000000&bg1=FFFFFF&f=ifr" style="height: 245px; padding-right: 10px; padding-top: 5px; width: 131px;"></iframe> are vulnerable to anyone with the correct reprogramming hardware. <br />
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Doctors use these wireless programming devices to make subtle adjustments to the heart helpers without the need for further surgeries. Unfortunately, the signal they use is unencrypted, meaning that anyone who finds a way to obtain such a device could literally manipulate the heart of a patient, causing cardiac arrest, or even death.<br />
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Insulin pumps are apparently even more susceptible to outside interference, and at the recent Black Hat hacker conference in Las Vegas, the life-saving pumps were shown to be vulnerable from distances of up to a half mile. Using power radio antennas, hackers can hijack a pump's wireless signal and cause it to give a blast of insulin to a wearer, with potentially deadly results.<br />
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<b>2. Baby monitors</b><br />
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Having a constant ear and eye on your baby's crib is something that most parents take for granted. Baby monitors have been around for a long time, and in recent years, video-equipped versions have become very popular with new parents. </span><br />
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<span class="fullpost"><span style="font-size: large;">What most users probably don't realize, is that the dozen or so wireless channels that these helpful devices use can often be picked up outside the home — giving anyone with a similar device or wireless receiver an undetectable window into your home.<br />
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The vulnerability of such monitor systems was highlighted in 2009 when an Illinois family sued the manufacturer of a baby monitor system they purchased at Toys R Us. <br />
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After using the system for months, a neighbor — who had recently purchased a similar system — alerted them that their monitor's camera was broadcasting its signal strong enough to be picked up in the neighboring house. The camera's microphone was so sensitive that the unsuspecting neighbors were able to hear entire conversations happening outside of the nursery where it was placed.<br />
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Newer baby monitor models feature "frequency hopping" technology that changes channels randomly to ensure privacy, but older, less-secure versions can still be found on store shelves. Check the features list on the side of the box when considering a monitor system to verify this very the device you're purchasing includes this new technology.<br />
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<b>3. Automobiles</b><br />
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Breaking into cars by smashing a window or picking a lock is so 90's. These days, security experts are worried about much more tech-savvy car thieves who can unlock your car, or even start it, simply by shooting it a text message or two. Many automotive systems — such as OnStar — utilize the same type of cellular technology as a common cell phone.<br />
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Demonstrating the hack at the Black Hat convention, security experts Don Bailey and Mathew Solnik explained how vulnerable new vehicles are to such manipulation. <br />
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Leaving out the details as to how the hack works — he is a security consultant after all — Bailey noted that the same hack could potentially affect infrastructure like power grids and traffic systems. But all it not lost — with just a few changes, car makers could close the door on hackers, though it won't be cheap.<br />
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Only vehicles with systems like OnStar are vulnerable in this way, and older, less feature-rich cars are immune to these advanced hacking techniques. Consider the risks when purchasing a vehicle with advanced connectivity and know that you can opt to have these features disabled if you think you may be vulnerable to theft.<br />
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<b>4. Garage door openers</b><br />
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A garage door opener is an extremely convenient device, but relying on a handheld gadget to be the gatekeeper of some of your most precious possessions can sometimes backfire. If you've ever taken a look inside your garage door opener to replace its batteries, or perhaps because you dropped it on the ground, you may have noticed a plethora of tiny wires and contact points. <br />
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Hackers can easily modify a standard door opener to accept a USB port, and software is readily available on the web to modify how it operates. A number of tutorials can be found online to walk an amateur hacker through the process of hacking your garage door in just minutes.<br />
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Thankfully, this vulnerability is typically only an issue for older garage door systems, and newer, more sophisticated openers use a rolling code that changes each time it is used. However, if your opener was made more than 5 years ago, there's a good chance it can easily be hacked, so consider upgrading if you can. <br />
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<b>5. The human brain</b><br />
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Of all the storage mediums you use to keep information that is most important to you, your brain is by far the most complex. Because of the immense amount of data that the human brain can hold, scientists have been attempting to crack our internal hard drives for quite some time. The scary part? They're actually getting close.<br />
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By building complex models of other brains in the animal kingdom — such as those of mice, cats, and primates — and then moving on to humans, researchers have begun to translate the trillions of impulses that go on in our heads into readable data. In fact, the Defense Advanced Research Projects Agency (DARPA) is funding a $4.9 million program to reverse-engineer the human brain in an effort to mine its computational abilities.<br />
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Some scientists, including Ray Kurzweil of Kurzweil Technologies, see a future where microscopic robots will be injected into a person's blood stream, head straight for the brain, and monitor activity. Of course, with the vulnerabilities of other medical implants already well documented, we'd hate to know the consequences of someone taking control of our brain's bots.</span><br />
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<span style="font-size: large;"><i><b>Source</b></i>: <a href="http://www.yahoo.com/" rel="nofollow"><i>Yahoo</i></a></span></span><br />
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Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-39130000158744724242011-08-16T17:42:00.000-07:002013-03-19T11:29:23.073-07:00Cell Phones (5)<br />
<span style="font-size: x-large;"><b>Analog Cell Phones</b></span><br />
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<tr><td class="tr-caption" style="text-align: center;">Analog Cell Phones</td></tr>
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<span style="font-size: large;">In 1983, the analog cell-phone standard called AMPS (Advanced Mobile Phone System) was approved by the FCC and first used in Chicago. AMPS uses a range of frequencies between 824 megahertz (MHz) and 894 MHz for analog cell phones. In order to encourage competition and keep prices low, the U. S. government required the presence of two carriers in every market, known as A and B carriers. One of the carriers was normally the local-exchange carrier (LEC), a fancy way of saying the local phone company.<br />
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Carriers A and B are each assigned 832 frequencies: 790 for voice and 42 for data. A pair of frequencies (one for transmit and one for receive) is used to create one channel. The frequencies used in analog voice channels are typically 30 kHz wide -- 30 kHz was chosen as the standard size because it gives you voice quality comparable to a wired telephone.<br />
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The transmit and receive frequencies of each voice channel are separated by 45 MHz to keep them from interfering with each other. Each carrier has 395 voice channels, as well as 21 data channels to use for housekeeping activities like registration and paging.<br />
<span style="font-size: large;">A version of AMPS known as Narrowband Advanced Mobile Phone Service (NAMPS) incorporates some digital technology to allow the system to carry about three times as many calls as the original version. Even though it uses digital technology, it is still considered analog. AMPS and NAMPS only operate in the 800-MHz band and do not offer many of the features common in digital cellular service, such as e-mail and Web browsing.</span><br />
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<span style="font-size: large;"><span class="fullpost"><span style="font-style: italic; font-weight: bold;">Source</span>: <a href="http://www.howstuffworks.com/" rel="nofollow">How Stuff Works</a></span></span><br />
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</span></span>Unknownnoreply@blogger.comtag:blogger.com,1999:blog-843912474116917256.post-72800576828555135932011-08-07T07:54:00.000-07:002012-01-09T09:37:13.283-08:00Cell Phones (4)<h1 class="articlePageTitle">
Cell-phone Codes</h1>
<span style="font-size: large;">All cell phones have special <b>codes</b> associated with them. These codes are used to identify the phone, the phone's owner and the service provider. </span><br />
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<span style="font-size: large;">Let's say you have a cell phone, you turn it on and someone tries to call you. Here is what happens to the call: </span></div>
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<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">When you first power up the phone, it listens for an <b>SID</b> (see sidebar) on the <b>control channel</b>. The control channel is a special frequency that the phone and base station use to talk to one another about things like call set-up and channel changing. If the phone cannot find any control channels to listen to, it knows it is <b>out of range</b> and displays a "no service" message. </span></li>
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<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">When it receives the SID, the phone <b>compares it</b> to the SID programmed into the phone. If the SIDs match, the phone knows that the cell it is communicating with is part of its <b>home</b> system. </span></li>
<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">Along with the SID, the phone also transmits a <b>registration request</b>, and the MTSO keeps track of your phone's location in a database -- this way, the MTSO knows which cell you are in when it wants to ring your phone. </span></li>
<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">The <b>MTSO</b> gets the call, and it tries to <b>find you</b>. It looks in its database to see which cell you are in. </span></li>
<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">The MTSO <b>picks a frequency pair</b> that your phone will use in that cell to take the call. </span></li>
<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">The MTSO communicates with your phone over the <b>control channel</b> to tell it which frequencies to use, and once your phone and the tower switch on those frequencies, the call is <b>connected</b>. Now, you are talking by two-way radio to a friend. </span></li>
<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">As you move toward the edge of your cell, your cell's <b>base station</b> notes that your <b>signal strength</b> is diminishing. Meanwhile, the base station in the cell you are moving toward (which is listening and measuring signal strength on all frequencies, not just its own one-seventh) sees your phone's signal strength increasing. The two base stations coordinate with each other through the MTSO, and at some point, your phone gets a signal on a control channel telling it to change frequencies. This <b>hand off</b> switches your phone to the new cell. </span></li>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhx8azIy_vwzPzLLYL-DKUxYAlEFRa8lo7vpV32YSO7NaTLtZc0PnAur1IGeHnwlPgeLR5sTrQsRa1yQtCZ0L0YJSSkBlIcZYPnISCduV1gNIkBkSjfuCjVtXoXv9OwfZkab21ro5CXcSo/s1600/Cell-to-Cell+Travel.JPG" style="margin-left: auto; margin-right: auto;"><img alt="Cell-to-Cell Travel:Hand off switches your phone to the new cell" border="0" id="BLOGGER_PHOTO_ID_5638127884927769186" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhx8azIy_vwzPzLLYL-DKUxYAlEFRa8lo7vpV32YSO7NaTLtZc0PnAur1IGeHnwlPgeLR5sTrQsRa1yQtCZ0L0YJSSkBlIcZYPnISCduV1gNIkBkSjfuCjVtXoXv9OwfZkab21ro5CXcSo/s320/Cell-to-Cell+Travel.JPG" style="display: block; height: 242px; margin: 0px auto 10px; text-align: center; width: 391px;" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">Hand off switches your phone to the new cell</span></b></td></tr>
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<span style="font-size: large;">Let's say you're on the phone and you move from one cell to another -- but the cell you move into is covered by another service provider, not yours. Instead of dropping the call, it'll actually be handed off to the other service provider. </span><br />
<span style="font-size: large;"> </span><span style="font-size: large;">If the SID on the control channel does not match the SID programmed into your phone, then the phone knows it is <b>roaming</b>. The MTSO of the cell that you are roaming in contacts the MTSO of your home system, which then checks its database to <b>confirm</b> that the SID of the phone you are using is valid. Your home system <b>verifies</b> your phone to the local MTSO, which then tracks your phone as you move through its cells. And the amazing thing is that all of this happens within seconds. </span><br />
<span style="font-size: large;"> </span><span style="font-size: large;">The less amazing thing is that you may be charged insane rates for your roaming call. On most phones, the word "roam" will come up on your phone's screen when you leave your provider's coverage area and enter another's. If not, you'd better study your coverage maps carefully -- more than one person has been unpleasantly surprised by the cost of roaming. Check your service contract carefully to find out how much you're paying when you roam. </span><br />
<span style="font-size: large;"> </span><span style="font-size: large;">Note that if you want to roam internationally, you'll need a phone that will work both at home and abroad. Different countries use different cellular access technologies. More on those technologies later. First, let's get some background on analog cell-phone technology so we can understand how the industry has developed. </span><br />
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<span style="font-size: large;">Cell Phone Codes</span></div>
<span style="font-size: large;"> </span><div class="MsoNormal" style="direction: ltr; text-align: left; unicode-bidi: embed;">
<span style="font-size: large;"><b>Electronic Serial Number</b> (ESN) - a unique 32-bit number programmed into the phone when it is manufactured<b><br />
</b><b>Mobile Identification Number</b> (MIN) - a 10-digit number derived from your phone's number<b><br />
</b><b>System Identification Code</b> (SID) - a unique 5-digit number that is assigned to each carrier by the FCC<span style="font-family: Arial;"> </span></span></div>
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<span style="font-size: large;"> <span style="font-family: Arial;">While the ESN is considered a permanent part of the phone, both the MIN and SID codes are programmed into the phone when you purchase a service plan and have the phone </span><span style="font-family: Arial;">activated</span>. </span></div>
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<span style="font-size: large;"><span style="font-style: italic; font-weight: bold;">Source</span>: <a href="http://www.howstuffworks.com/" rel="nofollow">How Stuff Works</a></span></div>
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</span></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-45854174198883650972011-07-28T12:07:00.000-07:002012-01-09T09:37:50.870-08:00Cell Phones (3)<span style="font-size: 24pt;">Cell-phone Channels</span><br />
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<span style="font-size: large;">A single cell in an analog cell-phone system uses one-seventh of the available duplex voice channels. That is, each cell (of the seven on a hexagonal grid) is using one-seventh of the available channels so it has a unique set of frequencies and there are no collisions: </span></div>
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<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">A cell-phone carrier typically gets 832 radio frequencies to use in a city. </span></li>
<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">Each cell phone uses two frequencies per call -- a duplex channel -- so there are typically <b>395 voice channels</b> per carrier. (The other 42 frequencies are used for <b>control channels</b> -- more on this later.) </span></li>
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<span style="font-size: large;">Therefore, each cell has about <b>56 voice channels</b> available. In other words, in any cell, 56 people can be talking on their cell phone at one time. Analog cellular systems are considered first-generation mobile technology, or <b>1G</b>. With digital transmission methods (2G), the number of available channels increases. For example, a <b>TDMA-based</b> digital system (more on TDMA later) can carry three times as many calls as an analog system, so each cell has about 168 channels available. </span></div>
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<span style="font-size: large;">Cell phones have <b>low-power transmitters</b> in them. Many cell phones have two signal strengths: 0.6 watts and 3 watts (for comparison, most CB radios transmit at 4 watts). The base station is also transmitting at low power. Low-power transmitters have two advantages: </span></div>
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<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">The <b>transmissions</b> of a base station and the phones within its cell do not make it very far outside that cell. Therefore, in the figure above, both of the purple cells can <b>reuse the same 56 frequencies</b>. The same frequencies can be reused extensively across the city. </span></li>
<li class="MsoNormal" style="direction: ltr; margin-left: 0.5in; margin-right: 0in; text-align: left; unicode-bidi: embed;"><span style="font-size: large;">The <b>power consumption</b> of the cell phone, which is normally battery-operated, is relatively low. Low power means small batteries, and this is what has made handheld cellular phones possible. </span></li>
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<span style="font-size: large;">The cellular approach requires a large number of base stations in a city of any size. A typical large city can have hundreds of towers. But because so many people are using cell phones, costs remain low per user. Each carrier in each city also runs one central office called the <b>Mobile Telephone Switching Office</b> (MTSO). This office handles all of the phone connections to the normal land-based phone system, and controls all of the base stations in the region.</span></div>
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<span style="font-size: large; font-style: italic; font-weight: bold;">Source</span><span style="font-size: large;">: <a href="http://www.howstuffworks.com/" rel="nofollow">How Stuff Works</a></span></div>
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</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-843912474116917256.post-30003271199077446652011-07-18T15:29:00.000-07:002012-01-09T09:38:23.264-08:00Cell Phones (2)<div class="hd">
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Cell-phone Frequencies</h1>
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<span style="font-size: large;">In the dark ages before cell phones, people who really needed mobile-communications ability installed <b>radio telephones</b> in their cars. In the radio-telephone system, there was one central antenna tower per city, and perhaps <b>25 channels</b> available on that tower. This <b>central antenna</b> meant that the phone in your car needed a powerful transmitter -- big enough to transmit 40 or 50 miles (about 70 km). It also meant that not many people could use radio telephones -- there just were not enough channels. </span><br />
<span style="font-size: large;"> The genius of the cellular system is the division of a city into small <b>cells</b>. This allows extensive <b>frequency reuse</b> across a city, so that millions of people can use cell phones simultaneously. </span><br />
<span style="font-size: large;"> A good way to understand the sophistication of a cell phone is to compare it to a CB radio or a walkie-talkie. </span><br />
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<li><span style="font-size: large;"><b>Full-duplex vs. half-duplex</b> - Both walkie-talkies and CB radios are <b>half-duplex</b> devices. That is, two people communicating on a CB radio use the same frequency, so only one person can talk at a time. A cell phone is a <b>full-duplex</b> device. That means that you use one frequency for talking and a second, separate frequency for listening. Both people on the call can talk at once. </span> </li>
<li><span style="font-size: large;"><b>Channels</b> - A walkie-talkie typically has one channel, and a CB radio has 40 channels. A typical cell phone can communicate on 1,664 channels or more! </span> </li>
<li><span style="font-size: large;"><b>Range</b> - A walkie-talkie can transmit about 1 mile (1.6 km) using a 0.25-watt transmitter. A CB radio, because it has much higher power, can transmit about 5 miles (8 km) using a 5-watt transmitter. Cell phones operate within <b>cells</b>, and they can switch cells as they move around. Cells give cell phones incredible range. Someone using a cell phone can drive hundreds of miles and maintain a conversation the entire time because of the cellular approach. </span></li>
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;"><span style="font-family: arial,helvetica;"><b>In half-duplex radio, both transmitters use the same frequency. Only one party can talk at a time.</b></span></span></td></tr>
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: arial,helvetica; font-size: large;"><b>In full-duplex radio, the two transmitters use different frequencies, so both parties can talk at the same time.<br />
Cell phones are full-duplex.</b></span></td></tr>
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<span style="font-size: large;">In a typical analog cell-phone system in the United States, the cell-phone carrier receives about <b>800 frequencies</b> to use across the city. The carrier chops up the city into cells. Each cell is typically sized at about <b>10 square miles</b> (26 square kilometers). Cells are normally thought of as hexagons on a big <b>hexagonal grid</b>, like this: </span></div>
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: arial,helvetica; font-size: large;"><b>Because cell phones and base stations use low-power transmitters, the same frequencies can be reused in non-adjacent cells. The two purple cells can reuse the same frequencies.</b></span></td></tr>
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Each cell has a <b>base station</b> that consists of a tower and a small building containing the radio equipment. We'll get into base stations later. First, let's examine the "cells" that make up a cellular system. </span><br />
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<span style="font-size: large;"><b><i>Source</i></b>: <a href="http://www.howstuffworks.com/" rel="nofollow">How Stuff Works</a></span><br />
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</span>Unknownnoreply@blogger.com0