work on docs
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@ -521,7 +521,7 @@ But you get a busy signal, that means there is no channel.
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</p>
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<p>
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Now run your base station on channel 1.
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Now run your base station on channel 1. (With SDR use channel 17.)
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You may add '-G x' or '--gfs x' command line option to change the station ID from default to any value you like. (see help)
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If you have a phone that supports GFS 19, please use this GFS 19 to reduce the transmit power of the phone to 100 mW instead of 15 Watts.
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To see if your phone supports it, try to preselect GFS 19.
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@ -22,7 +22,7 @@ History
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</p>
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<p>
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C-Netz was the third mobile telephone network in Germany.
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C-Netz (aka C450 or C-Tel) was the third mobile telephone network in Germany.
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It existed between 1984 (officially Mai 1985) and December 2000.
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In 1989, the German Wall came down and C-Netz was quickly deployed in eastern Germany to support the congested telephone network.
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It was the first cellular system in Germany, so frequencies could be used more efficiently, as it had been done in the USA with AMPS.
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@ -27,8 +27,7 @@ NMT was a Scandinavian cellular network, developed by and used in Scandinavian c
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If was used in the Baltic countries, Switzerland, Netherlands, Hungary, Poland, Bulgaria, Romania, Czech Republic, Slovakia, Slovenia, Serbia, Turkey, Croatia, Bosnia, Russia, Ukraine and in Asia.
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The NMT network was opened in Sweden and Norway in 1981, and in Denmark and Finland in 1982. Iceland joined in 1986.
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Networks where shut down in 2000 (Estonia), 2002 (Finland), 2004 (Norway), 2007 (Sweden), 2010 (Iceland).
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In 1989, the German Wall came down and C-Netz was quickly deployed in eastern Germany to support the congested fixed network.
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It was a cellular system, so frequencies could be used efficiently..
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It was a cellular system, so frequencies could be used efficiently.
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It offered handover capability, so moving phones could change cells during a call.
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Authentication was introduces (SIS), to prevent fraud, but it was optional.
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Older phones without SIS could be cloned by receiving and decoding the roaming update message.
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@ -23,6 +23,38 @@
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History
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</p>
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<p>
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Radiocom 2000 (sometimes R2000) was a cellular network used in France.
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The network was developed by France Telekom and Matra and became the third mobile network.
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There are many similarities to the NMT network, but it was a complete own design.
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Development started in 1981 and the network was launched in Paris in 1985, it gradually replaced the second network "correspondance publique".
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It was a cellular system, so frequencies could be used efficiently.
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The system was capable of allocating channels dynamically.
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Handover was implemented later and called RHD "Réseau Haute Densité" (network with high desity).
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It was possible to run private base station, where own mobiles were allowed to call only.
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In 1988, it had 60,000 subscribers and more than 90% of devices are installed in vehicles.
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Originally the 200 MHz and 400 MHz bands were used.
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Due to congesting in 1990, the 900 MHz band was introduced.
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The network was closed for the exclusive benefit of the standard GSM in July 28th 2000.
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</p>
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<p>
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<ul>
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<li>Frequency range UHF: 424.800 - 427.9875 MHz (down-link); 414.800 - 417.9875 MHz (up-link)
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<li>256 voice or contol channels
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<li>Duplex distance: 10 MHz
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<li>Channel spacing: 12.5 KHz
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<li>Voice modulation: FM
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<li>Signaling modulation: carrier FSK
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<li>Frequency deviation: 1500 Hz ??? (Voice); 1425 Hz (FSK)
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<li>Mobile station transmit power: 1 or 6..10 Watts
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<li>Features: Speech Compandor (BS->MS only), Group calls
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</ul>
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</p>
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<p>
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</p>
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<p class="toppic">
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<a name="howitworks"></a>
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How it works
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@ -107,8 +107,8 @@ You will get an ASCII art plot of received IQ data.
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Press 'q' again and you will get a logarithmic view of IQ vectors.
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Press 'q' again to turn off this view.
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Please monitor this view when the phone tries to call or register.
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If the dots are yellow or red, the received signal overdrives the ADC.
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If the linear view shows not a nice, skinny circle, if the phone transmits, the input of your SDR might be saturated.
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If the dots are yellow, or red, the received signal may overdrive the ADC.
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Especially when the linear view shows a deformed circle (or even rectangle), reduce RX level.
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</p>
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<center><img src="display-spectrum.png"/></center>
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@ -116,7 +116,7 @@ If the linear view shows not a nice, skinny circle, if the phone transmits, the
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<p>
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Press 's' to get an ASCII art graph of received frequency spectrum.
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The spectrum's bandwidth is defined by the sample rate (-s) and not by the SDR sample rate!
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If you don't get this nice peak, but maybe several peaks, you might have the input over-driven.
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If you don't get nice peaks, but maybe several peaks, you might over-driven the input.
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Note that the peak will spread by the frequency deviation, so the peak might look noisy on the top.
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If the peak is quite low, check the input gain.
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</p>
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@ -277,6 +277,63 @@ It can be used to check a headset.
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Everything that is spoken into the microphone should appear on the headphone.
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</p>
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<p class="toppic">
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On-screen displays
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</p>
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<center><img src="display-wave.png"/></center>
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<p>
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Essentially for monitoring the input level is the 'w' key.
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You will get an ASCII art plot of received audio signal.
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Press 'w' again to turn off this view.
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</p>
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<center><img src="display-measurements.png"/></center>
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<p>
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To check measurements like input level and quality, press the 'm' key.
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You will get an ASCII art plot of differen bar graphs.
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They show tone / frame level and quality.
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The green bar shows the current level.
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The yellow marker shows the last/peak/average level.
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The light blue marker shows the target level.
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Some measurement like RF level, frequency offset and peak deviation are only available with SDR.
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Press 'm' again to turn off this view.
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</p>
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<center><img src="display-iq.png"/></center>
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<p>
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Only works with SDR:
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You can monitor IQ data by pressing 'q' key.
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You will get an ASCII art plot of received IQ data.
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Press 'q' again and you will get a logarithmic view of IQ vectors.
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Press 'q' again to turn off this view.
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Please monitor this view when the phone tries to call or register.
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If the dots are yellow, or red, the received signal may overdrive the ADC.
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Especially when the linear view shows a deformed circle (or even rectangle), reduce RX level.
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</p>
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<center><img src="display-spectrum.png"/></center>
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<p>
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Only works with SDR:
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Press 's' to get an ASCII art graph of received frequency spectrum.
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The spectrum's bandwidth is defined by the sample rate (-s) and not by the SDR sample rate!
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If you don't get nice peaks, but maybe several peaks, you might over-driven the input.
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Note that the peak will spread by the frequency deviation, so the peak might look noisy on the top.
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If the peak is quite low, check the input gain.
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Press 's' again to turn off this view.
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</p>
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<center><img src="display-status.png"/></center>
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<p>
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Current transceiver and call state can be viewed by pressing 'c' key.
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Press 'c' again to turn off this view.
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</p>
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<hr><center>[<a href="index.html">Back to main page</a>]</center><hr>
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</td></tr></table></center>
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</body>
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