forked from cellular-infrastructure/osmocom-analog
616 lines
29 KiB
HTML
616 lines
29 KiB
HTML
<html>
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<head>
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<link href="style.css" rel="stylesheet" type="text/css" />
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<title>osmocom-analog</title>
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</head>
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<body>
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<center><table><tr><td>
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<h2><center>C-Netz</center></h2>
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<center><img src="c-netz.jpg"/></center>
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<ul>
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<li><a href="#history">History</a>
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<li><a href="#howitworks">How it works</a>
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<li><a href="#basestation">Setup of a base station</a>
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</ul>
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<p class="toppic">
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<a name="history"></a>
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History
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</p>
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<p>
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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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It offered handover capability, so moving phones could change the smaller cells during a call.
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The SIM card was introduced, which is similar to GSM.
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This card allowed to use phones by different subscribers with different subscriber numbers.
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Authentication was used to prevent fraud, but it was used only with SIM card phones.
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The magnetic cards could be cloned by receiving 'roaming update' messages.
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Extra services (e. g. conditional call forwarding, answering machine) were installed in the mobile exchange.
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A voice scrambler inside the phone and base station prevented eavesdropping with radio scanners.
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The scrambler inverted the audio spectrum, so one cannot understand any word without de-scrambling.
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Phones became smaller and portable, even hand-held phones were available.
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In Germany these hand-held phones are called 'Handies'.
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All phones were available under a dedicated prefix.
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A caller must not know the location of the phone anymore to reach the right base station.
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</p>
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<center><img src="c-netz-c130.jpg"/></center>
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<p>
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<ul>
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<li>Frequency range: 461.010 - 465.740 MHz (down-link); 451.010 - 465.740 MHz (up-link)
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<li>Extended frequency range: 460.010 - 465.740 MHz (down-link); 450.010 - 465.740 MHz (up-link)
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<li>222 voice channels
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<li>237 voice channels since Mai 1988
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<li>287 voice channels since September 1989
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<li>1 organization channel (call setup and paging)
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<li>Duplex distance: 10 MHz
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<li>Channel spacing: 10 KHz and optionally 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: 2.5 KHz (FSK); 4 KHz (Voice)
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<li>Mobile station transmit power: 50 mW up to 15 Watts
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<li>Base station transmit power: 25 Watts
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<li>Features: Speech Compandor, Audio scrambling
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</ul>
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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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</p>
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<p>
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Like AMPS (Advanced Mobile Phone Service), the C-Netz is a cellular network.
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Smaller cells allowed more calls to be made with same amount of radio channels.
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</p>
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<center><img src="c-netz_zellstruktur.png"/></center>
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<p>
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Base stations are grouped into clusters.
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Each cluster is made of around 7 base stations.
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Each base station in a cluster must have different channels.
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As depicted, the channels of a base station marked with "1" can be re-used in other clusters that is marked "1" also.
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To handle more calls with the same amount of channels, the size of a cell was reduced in highly populated areas.
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By using small cell structure, it was likely to loose radio link while calling and moving at the same time.
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To prevent loss of radio link while moving too far away from a cell, handover to stronger or closer cell is performed.
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</p>
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<center><img src="c-netz_frequenzen.png"/></center>
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<p>
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Two frequency bands are used, one for up-link and one down-link.
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Only one exception is the control channel #131 ('Orgakanal').
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It is the same channels for all base stations.
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To avoid collisions, the channel is divided into time slots.
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The time slots are re-used in the same way as channels are re-used in other clusters.
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This reduces the number of channels for call setup and paging to only one single channel.
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The mobile phone does not have to search for a valid control channel first, it just has to tune to channel 131.
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Also it is possible to have a dedicated control channel for cells in high traffic areas.
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</p>
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<center><img src="c-netz_zeitschlitze.png"/></center>
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<p>
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As depicted, the base station and mobile station use one or more time slots on the control channel.
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Generally, every 8th time slot was used and is used by this project.
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The base station transmits every 600ms in this case.
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The mobile phone transmits two time slots later, if required.
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Every time slot contains two message blocks.
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One block is used for call setup.
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The other block is used for periodic check, if the phone is still available.
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</p>
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<p>
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Message blocks have 70 bits.
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The first 6 bits define the message type.
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The other 64 bits are information elements, depend on the message type.
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The 70 bits are grouped into 10 words of 7 bits each.
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Each word gets additional 8 bits redundancy from a BCH code.
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The redundancy allows to correct up to two bit errors in a word.
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</p>
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<center><img src="c-netz_interleaving.png"/></center>
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<p>
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To correct burst errors (up to 20 bits), the bits are interleaved before transmitted.
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As depicted above, the first bit of all words are transmitted first, then the next bit and so on.
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</p>
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<center><img src="c-netz_frame_k.png"/></center>
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<p>
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A sync word of 11 bits is added in front of each message three times, followed by one unused bit.
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Additional 14 guard bits are used to allow the transmitter to ramp up and down RF power between time slots.
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This gives a total of 198 bits per message and a duration of 37.5 ms.
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</p>
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<center><img src="c-netz_frame_v.png"/></center>
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<p>
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Also message blocks are transmitted during voice conversation.
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The blocks are used to terminate the call, perform handover, measure link or transmit metering information.
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4 bits of the message is transmitted every 12.5 ms. After 600 ms, the complete frame is transmitted.
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To remove the 4 bits from audio stream, the voice is time compressed (speed up) to 10/11th.
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The 4 bits + 2 guard bits are inserted in the gap between voice chunks.
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On the receiving end, the voice chunks are expanded again.
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The phone will keep in sync with the voice chunks by keeping the decoder in sync with the received message bits.
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</p>
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<center><img src="c-netz_frame_v2.png"/></center>
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<p>
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The audio level at the end of one voice chunk may not match the level at the beginning of the next chunk.
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This offset must be removed by the receiver using a filter.
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</p>
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<center><img src="c-netz_lr.png"/></center>
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<p>
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This is an example of a broadcast message by a base station on the control channel.
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The message type 'O' (letter o) is "100111", so this message block contains cell and access information.
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</p>
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<center><img src="c-netz_symbole.png"/></center>
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<p>
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The location of parameters inside a message (information elements) are shown by letters.
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Each letter is a different information element as depicted above.
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</p>
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<center><img src="c-netz_call.png"/></center>
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<p>
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The first thing a phone does is looking for the strongest cell.
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The phone accesses the cell by transmitting a location update message.
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The cell acknowledges or rejects the phone.
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</p>
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<p>
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The call setup is depicted above.
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The mobile phone transmits a message that it wishes to make a normal call or emergency call.
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If the channel is available, the base station requests the dialed number from the phone.
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The phone transmits the dialed number.
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If the number is ok, the base station acknowledges the dialed number.
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After a voice channel is allocated, the base station orders the phone to change to that channel two time slots later.
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On this voice channel, the mobile phone and the base station transmit 8 messages to prove quality of channel.
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Messages VH1 and VHK are transmitted while the call is set up.
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Then the phone is ordered to switch to voice conversation.
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All following messages are then transmitted between the voice chunks.
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</p>
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<p>
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To reduce radio noise, a syllabic compandor is used on both ends.
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This compresses the audio level dynamics by 2.
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An audio level of 25% is raised to 50% by the compressor and lowered to 25% by the expander.
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A radio noise floor of 10% would be reduced to 1% this way.
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</p>
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<p>
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Scrambling is used to prevent eavesdropping with radio scanners.
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The audio spectrum of 300 - 3300 Hz is inverted by mirroring frequencies about 1650 Hz at the transmitter.
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(1000 Hz becomes 2300 Hz and vice versa.)
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The receiver mirrors again to unscramble audio.
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To scramble audio efficiently, a carrier frequency of 3300 Hz is amplitude modulated (multiplied) by the audio signal.
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The result is a shifted spectrum above 3300 Hz and a mirrored spectrum below 3300 Hz.
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The spectrum above 3300 Hz is filtered out, so the mirrored spectrum remains.
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</p>
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<p>
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See the German description from <a href="mobilfunk/c.html">Handbuch von Josef Kedaj / G<>nther Hentschel</a> for more informations.
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</p>
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<p class="toppic">
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<a name="basestation"></a>
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Setup of a base station
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</p>
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<p>
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When I first started testing my early C-Netz implementation, I had great trouble getting a response from any mobile phone.
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The main problem was clock speed of the transmitted signal.
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In the real network, the base stations were all synchronized with a high precision clock.
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All base stations transmit on the same control channel 131 ('Orgakanal'), but at different time slots.
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The phone expects that the time slots repeat precisely every 2.4 seconds.
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The specification say that the mobile phone requires clock speed deviation of +- 1 PPM (Parts Per Million) or less.
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To comply with the specs, the base stations needs to have a clock deviation far below 1 PPM.
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(I guess that there is a tolerance, so maybe a few PPM deviation would make no big problem.)
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We need to calibrate the speed of our transmit signal (and receive signal as well).
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</p>
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<p>
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<font color="red">Important: We need calibrate the signal processing clock!</font>
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<br><br>
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You can skip this parts, if you use SDR, because they have more accurate crystals than sound cards.
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</p>
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<p>
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First of all we need a reference clock.
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Since most computers have standard crystal clocks, we cannot use our system clock without any help.
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I decided to use the help of the NTP daemon.
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After running my system for one up to 5 days, the clock speed was accurate enough for a base station.
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Be sure to choose a place for your PC with constant temperature.
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A room inside a building is sufficient.
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</p>
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<p>
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In /etc/ntp.conf define one or more NTP servers to get the time from. I use the German atom clock of the PTB:
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</p>
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<pre>
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server ntp1.ptb.de
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server ntp2.ptb.de
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server ntp3.ptb.de
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</pre>
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<p>
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This clock provides time base for European radio clocks and most German clocks.
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It accurate enough for this project, so please use this clock for my project.
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</p>
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<pre>
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netbook ~ # ntptime
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ntp_gettime() returns code 0 (OK)
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time dad971f1.9e1b5c44 Sun, May 8 2016 10:06:09.617, (.617605507),
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maximum error 238951 us, estimated error 199 us, TAI offset 0
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ntp_adjtime() returns code 0 (<font color="red">OK</font>)
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modes 0x0 (),
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offset 425.797 us, frequency <font color="red">15.796 ppm</font>, interval 1 s,
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maximum error 238951 us, estimated error 199 us,
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status 0x2001 (PLL,NANO),
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time constant 10, precision 0.001 us, tolerance 500 ppm,
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</pre>
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<p>
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One notices that I have quite an low precision crystal in my test machine.
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Since I have NTP running for at least 5 days, the system clock is now far below 1 PPM.
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</p>
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<p>
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The second problem is the clock of our sound adapter.
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They use own crystals that are also not accurate.
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Because they are made for audio signals (and not for high precise base stations), they can't be used without calibration.
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Cheap USB adapters may even have different clocks on TX and RX.
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Be sure to use no extension cables for USB sound adapters, since the voltage may drop undefined and so the clock speed will change.
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</p>
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<p>
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Since we have precise system clock now (thanx to NTP), we can measure the speed difference of our sound adapter.
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Later we will use the measurement result to adjust our signal processor, so the signal clock is below 1 ppm.
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Be sure to have your machine running for at least 5 to 7 days (with your sound adapter attached, in case you have USB sound adapter).
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The machine must have network connection to the NTP server.
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I suggest to use 'ntp1.ptb.de' and 'ntp2.ptb.de' as reference.
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Use other servers if you are sure that the source is an atomic clock.
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Use command line option '-M' or '--measure' to measure my sound adapter.
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Let it run for one hour.
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</p>
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<pre>
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# src/cnetz/cnetz -k 131 -M
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...
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dsp.c:218 notice : Clock: RX=4.75 TX=36.84; Signal: RX=135.38 TX=-378.58 ppm
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dsp.c:218 notice : Clock: RX=10.61 TX=31.09; Signal: RX=135.38 TX=-378.58 ppm
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dsp.c:218 notice : Clock: RX=3.01 TX=26.55; Signal: RX=135.38 TX=-378.58 ppm
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...
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dsp.c:218 notice : Clock: RX=19.46 TX=19.45; Signal: RX=19.39 TX=19.42 ppm
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dsp.c:218 notice : Clock: RX=19.45 TX=19.50; Signal: RX=19.39 TX=19.42 ppm
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dsp.c:218 notice : Clock: RX=19.48 TX=19.47; Signal: RX=19.39 TX=19.42 ppm
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dsp.c:218 notice : Clock: RX=19.44 TX=19.44; Signal: RX=19.35 TX=19.43 ppm
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dsp.c:218 notice : Clock: RX=19.44 TX=19.49; Signal: RX=19.35 TX=19.43 ppm
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</pre>
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<p>
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One can see that the measured clock from the sound card (sample rate) differs about +19.45 PPM.
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Because I did not do any correction to the signal processing, the same error applies to the signal processing.
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Use command line option '-C 19.45,19.45' or '--clock-speed 19.45,19.45' to compensate the clock error by adjusting the signal processor.
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Let it run again for one hour and you will see that clock deviation of the signal is below 1 PPM.
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</p>
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<p>
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<font color="red">Important: We need to connect to PLL and discriminator!</font>
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</p>
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<p>
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C-Netz does not use a modulated tone to carry bits of information, instead it modulates the radio carrier directly.
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This image shows the demodulated signal from a receiver:
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</p>
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<center><img src="c-netz-burst_full.png"/></center>
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<p>
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Generally a receiver will do de-emphasis and filtering after demodulating the signal.
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We don't want that.
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It may work, but be sure to use a receiver with discriminator output.
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This output gives direct signal of the frequency deviation of the received signal.
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The signal on the sound card represents the frequency shift of the received signal.
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Many receivers can be modified, so search the Web for more info.
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</p>
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<p>
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On the transmitter we don't want to have filtering and pre-emphasis.
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It may work, but be sure to use a transmitter that allows to disable emphasis.
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I took the schematics of my transmitter and connected the sound card directly to the PLL.
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The transmitter will now shift frequency according the the level of the sound card.
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</p>
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<p>
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<font color="red">Important: We need to transmit correct polarity! Always use 'auto' (default) to automatically detect the correct polarity.</font>
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</p>
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<center><img src="c-netz-burst_part.png"/></center>
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<p>
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C-Netz uses FSK (Frequency Shift Keying) by directly modulating the carrier frequency, rather than modulating a tone.
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The advantage is much higher data rate.
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The base station's carrier frequency is raised by 2.5 KHz to transmit a logical "1" and lowered by 2.5 KHz to transmit a logial "0".
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(The mobile station transmits reversed polarity.)
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The mobile station will only decode signals with the correct polarity.
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The three sync words of "11100010010", is shown in the picture above.
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In the picture above, the polarity is wrong.
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(The logical "1" points down and the logical "0" points up.)
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To change transmitted polarity, use command line option '-F yes|no|auto' or '--flip-polarity yes|no|auto'.
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(Note: don't confuse with '-P'!)
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</p>
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<p>
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The 'auto' option (default) will generate a signal of two base stations.
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If we don't know the polarity of our sound card or transmitter, this helps to detect the right polarity.
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Since we have time division multiplex on the main control channel, we can transmit a second base station by using different time slots.
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The second base station uses reversed polarity, so there is one base station with correct and one with wrong polarity.
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The two base stations have different time slots and different IDs.
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If a first registration message is received from the mobile phone, the software checks to which base station this response belongs to.
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Then we found the correct polarity and turn off the base station with the wrong polarity.
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</p>
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<p>
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The decoder itself does not care about what polarity it receives from the mobile station.
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We don't need to know the polarity of the receiver or the sound card's input.
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The software just checks for sync words with both possible polarities and chooses right polarity automatically.
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</p>
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<p>
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I have a transmitter and a receiver without emphasis, my sound card has a clock error of about 19.2 PPM.
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To run the base station I the following command line options:
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</p>
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<pre>
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# cnetz -k 131 -p -d -C 19.25,19.25
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...
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cnetz.c:142 notice : You selected channel 131 ('Orga-Kanal') for combined callin
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g + traffic channel. Some phones will reject this.
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dsp.c:96 info : Using clock speed of 19.2 ppm (RX) and 19.2 ppm (TX) to correc
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t sound card's clock.
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cnetz.c:274 info : Entering IDLE state on channel 131.
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Base station on channel 131 ready, please tune transmitter to 465.090 MHz and re
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ceiver to 455.090 MHz.
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</pre>
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<p>
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The software complains about using control channel 131 for voice traffic too.
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This is the easiest way to use a single transmitter and receiver without switching.
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But this is not compliant, so especially newer phone will reject this, like the Nokia C130.
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Old phones like BSA, Storno or Phillips phones don't care.
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When we make a call and another phone is registered, the other phone will loose coverage when the software switches from control channel to traffic channel.
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After the call has been terminated, the control channel is restored and the other phone re-registers again.
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</p>
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<p>
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You should tune the receiver to 465.090 first, to check if you can hear and decode the idle signal from the base station.
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Then tune to actually up-link frequency 455.090 MHz.
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The actual level is not yet relevant.
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(You may check the quality using '-l 2' or '--loopback 2' command line option and build a radio loop by tuning the receiver to the transmitter.)
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</p>
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<p>
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Now power up a phone.
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Depending on your card reader, insert chip or magnetic card.
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Hopefully you get a response from the phone.
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If it responds, you will hear a short burs on receiver.
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This bursts is just 37.5 ms long and sounds a bit less noisy than the noise floor.
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If the burst is received and correctly decoded, the base station knows the transmitter's polarity and selects it.
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</p>
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<pre>
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telegramm.c:1486 info : RX Level: 96% Jitter: 0.04 Sync Time: 3968.18 (TS 10.02) POSITIVE
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***********************************************
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*** Autoselecting positive FSK TX polarity! ***
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***********************************************
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cnetz.c:895 info : Received Attachment 'Einbuchen' message from Subscriber '6215784' with chip card's security code 11029
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transaction.c:208 info : Transaction state IDLE -> EM
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transaction.c:70 info : Created transaction for subscriber '6215784'
|
||
database.c:117 info : Adding subscriber '6,2,15784' to database.
|
||
database.c:121 info : Subscriber '6,2,15784' busy now.
|
||
cnetz.c:709 notice : Frame sync offset = 800.18, correcting!
|
||
cnetz.c:760 info : Sending acknowledgement 'Einbuchquittung' to Attachment request.
|
||
database.c:124 info : Subscriber '6,2,15784' idle now.
|
||
transaction.c:89 info : Destroying transaction for subscriber '6215784'
|
||
transaction.c:208 info : Transaction state EM -> IDLE
|
||
|
||
</pre>
|
||
|
||
<p>
|
||
Level adjustment:
|
||
We see a receive level of around 96%.
|
||
This is already good, since I did the adjustment previously.
|
||
Tune your receiver to the up-link frequency, so you get loop-back of base station broadcast.
|
||
Use the variable resistor (connecting your transmitter) to adjust the volume until the received level matches the same level of your previously received message.
|
||
In my case I adjust the transmitter to match around 96%. (+- 10% is good)
|
||
Now, whatever frequency deviation the phone transmits for signaling, so does your base station.
|
||
Use the other variable resistor (connecting your receiver) to adjust the volume until the level matches about 100%. (+- 10% is good)
|
||
Switch back the receiver to up-link frequency and restart the phone.
|
||
</p>
|
||
|
||
<p>
|
||
After some time (1 minute) the base station will check, if the phone is still available.
|
||
It transmits a request (MA) to the phone.
|
||
The phone answers to the request (MFT):
|
||
</p>
|
||
|
||
<pre>
|
||
|
||
telegramm.c:1473 info : Ignoring mysterious unmodulated telegramm (noise from phone's transmitter)
|
||
database.c:72 info : Check, if subscriber '6,2,15784' is still available.
|
||
transaction.c:208 info : Transaction state IDLE -> MA
|
||
transaction.c:70 info : Created transaction for subscriber '6215784'
|
||
database.c:121 info : Subscriber '6,2,15784' busy now.
|
||
cnetz.c:863 info : Sending keepalive request 'Meldeaufruf'
|
||
transaction.c:208 info : Transaction state MA -> MFT
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.02 Sync Time: 6534.01 (TS 16.50) POSITIVE
|
||
cnetz.c:969 info : Received acknowledge 'Meldung Funktelefonteilnehmer' message from Subscriber '6215784'
|
||
database.c:124 info : Subscriber '6,2,15784' idle now.
|
||
transaction.c:89 info : Destroying transaction for subscriber '6215784'
|
||
transaction.c:208 info : Transaction state MFT -> IDLE
|
||
|
||
</pre>
|
||
|
||
<p>
|
||
To make a call from the mobile phone to the base station, just enter some digits at the mobile phone and press the dial button.
|
||
The phone requests a call (VWG).
|
||
The base station requests dialed number (WAF).
|
||
The phone transmits dialed number (WUE).
|
||
The base station acknowledges the call (WBP) and then orders the phone to switch to speech channel (VAG).
|
||
Then measurement and through connection of speech takes place:
|
||
</p>
|
||
|
||
<pre>
|
||
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.04 Sync Time: 12671.99 (TS 32.00) POSITIVE
|
||
cnetz.c:931 info : Received outgoing Call 'Verbindungswunsch gehend' message from Subscriber '6215784'
|
||
transaction.c:208 info : Transaction state IDLE -> VWG
|
||
transaction.c:70 info : Created transaction for subscriber '6215784'
|
||
database.c:121 info : Subscriber '6,2,15784' busy now.
|
||
cnetz.c:854 info : Sending acknowledgement 'Wahlaufforderung' to outging call
|
||
transaction.c:208 info : Transaction state VWG -> WAF
|
||
telegramm.c:1486 info : RX Level: 95% Jitter: 0.04 Sync Time: 3366.02 (TS 8.50) POSITIVE
|
||
cnetz.c:957 info : Received dialing digits 'Wahluebertragung' message from Subscriber '6215784' to Number '02123839349'
|
||
transaction.c:208 info : Transaction state WAF -> WBP
|
||
cnetz.c:782 info : Sending call accept 'Wahlbestaetigung positiv'.
|
||
transaction.c:208 info : Transaction state WBP -> VAG
|
||
cnetz.c:789 info : Sending channel assignment 'Verbindungsaufbau gehend'.
|
||
transaction.c:208 info : Transaction state VAG -> BQ
|
||
cnetz.c:807 info : Staying on combined calling + traffic channel 131
|
||
dsp.c:641 info : Switching channel (mode)
|
||
cnetz.c:1014 info : Sending 'Belegungsquittung' on traffic channel
|
||
cnetz.c:1014 info : Sending 'Belegungsquittung' on traffic channel
|
||
cnetz.c:1014 info : Sending 'Belegungsquittung' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.02 Sync Time: 9504.02 (TS 24.00) POSITIVE
|
||
cnetz.c:1118 info : Received allocation 'Belegung' message.
|
||
cnetz.c:1014 info : Sending 'Belegungsquittung' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.02 Sync Time: 9701.99 (TS 24.50) POSITIVE
|
||
cnetz.c:1118 info : Received allocation 'Belegung' message.
|
||
...
|
||
transaction.c:208 info : Transaction state BQ -> VHQ
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.03 Sync Time: 10494.00 (TS 26.50) POSITIVE
|
||
cnetz.c:1118 info : Received allocation 'Belegung' message.
|
||
cnetz.c:1024 info : Sending 'Quittung Verbindung halten' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.03 Sync Time: 10691.98 (TS 27.00) POSITIVE
|
||
cnetz.c:1118 info : Received allocation 'Belegung' message.
|
||
...
|
||
call.c:623 info : Incoming call from '6215784' to '02123839349'
|
||
transaction.c:208 info : Transaction state VHQ -> DS
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.02 Sync Time: 11286.00 (TS 28.50) POSITIVE
|
||
cnetz.c:1145 info : Received connection hold 'Verbindung halten' message.
|
||
cnetz.c:1051 info : Sending 'Durchschalten' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.03 Sync Time: 11483.99 (TS 29.00) POSITIVE
|
||
cnetz.c:1145 info : Received connection hold 'Verbindung halten' message.
|
||
...
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.03 Sync Time: 12276.00 (TS 31.00) POSITIVE
|
||
cnetz.c:1131 info : Received assignment confirm 'Durchschaltung Quittung' message.
|
||
cnetz.c:1051 info : Sending 'Durchschalten' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 97% Jitter: 0.02 Sync Time: 12474.01 (TS 31.50) POSITIVE
|
||
cnetz.c:1131 info : Received assignment confirm 'Durchschaltung Quittung' message.
|
||
...
|
||
transaction.c:208 info : Transaction state DS -> VHQ
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.03 Sync Time: 1781.99 (TS 4.50) POSITIVE
|
||
cnetz.c:1131 info : Received assignment confirm 'Durchschaltung Quittung' message.
|
||
dsp.c:641 info : Switching channel (mode)
|
||
cnetz.c:1238 info : Sending 'Quittung Verbindung halten' on traffic channel
|
||
cnetz.c:1238 info : Sending 'Quittung Verbindung halten' on traffic channel
|
||
cnetz.c:1238 info : Sending 'Quittung Verbindung halten' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 97% Jitter: 0.07 Sync Time: 5544.05 (TS 14.00) POSITIVE
|
||
cnetz.c:1286 info : Received supervisory frame 'Verbindung halten' message.
|
||
cnetz.c:1238 info : Sending 'Quittung Verbindung halten' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 97% Jitter: 0.07 Sync Time: 8712.02 (TS 22.00) POSITIVE
|
||
cnetz.c:1286 info : Received supervisory frame 'Verbindung halten' message.
|
||
cnetz.c:1238 info : Sending 'Quittung Verbindung halten' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 97% Jitter: 0.09 Sync Time: 11880.04 (TS 30.00) POSITIVE
|
||
cnetz.c:1286 info : Received supervisory frame 'Verbindung halten' message.
|
||
cnetz.c:1238 info : Sending 'Quittung Verbindung halten' on traffic channel
|
||
...
|
||
|
||
</pre>
|
||
|
||
<p>
|
||
To call to the mobile phone, enter the mobile station's ID and press 'd' for dial.
|
||
If the phone is attached, the base station orders the phone to switch to speech channel (VAK).
|
||
The rest is similar to incoming calls, except the the phone has to answer before the speech is through-connected:
|
||
</p>
|
||
|
||
<pre>
|
||
|
||
call.c:490 info : Outgoing call to 6215784
|
||
cnetz.c:416 info : Call to mobile station, paging station id '6215784'
|
||
transaction.c:208 info : Transaction state IDLE -> VAK
|
||
transaction.c:70 info : Created transaction for subscriber '6215784'
|
||
database.c:121 info : Subscriber '6,2,15784' busy now.
|
||
cnetz.c:792 info : Sending channel assignment 'Verbindungsaufbau kommend'.
|
||
transaction.c:208 info : Transaction state VAK -> BQ
|
||
cnetz.c:807 info : Staying on combined calling + traffic channel 131
|
||
dsp.c:641 info : Switching channel (mode)
|
||
cnetz.c:1014 info : Sending 'Belegungsquittung' on traffic channel
|
||
cnetz.c:1014 info : Sending 'Belegungsquittung' on traffic channel
|
||
cnetz.c:1014 info : Sending 'Belegungsquittung' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.03 Sync Time: 6335.99 (TS 16.00) POSITIVE
|
||
cnetz.c:1118 info : Received allocation 'Belegung' message.
|
||
cnetz.c:1014 info : Sending 'Belegungsquittung' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 95% Jitter: 0.03 Sync Time: 6534.06 (TS 16.50) POSITIVE
|
||
cnetz.c:1118 info : Received allocation 'Belegung' message.
|
||
|
||
</pre>
|
||
|
||
<p>
|
||
When the mobile phone is hung up, it sends the AT message.
|
||
The base station responds with AF message and switches back to control channel.
|
||
</p>
|
||
|
||
<pre>
|
||
|
||
telegramm.c:1486 info : RX Level: 97% Jitter: 0.06 Sync Time: 11880.01 (TS 30.00) POSITIVE
|
||
cnetz.c:1286 info : Received supervisory frame 'Verbindung halten' message.
|
||
cnetz.c:1238 info : Sending 'Quittung Verbindung halten' on traffic channel
|
||
telegramm.c:1486 info : RX Level: 97% Jitter: 0.06 Sync Time: 2375.99 (TS 6.00) POSITIVE
|
||
cnetz.c:1297 info : Received release frame 'Ausloesen durch FuTln' message.
|
||
transaction.c:208 info : Transaction state VHQ -> AT
|
||
call.c:744 info : Call has been released with cause=16
|
||
cnetz.c:1253 info : Sending 'Auslosen durch FuTln' on traffic channel
|
||
database.c:124 info : Subscriber '6,2,15784' idle now.
|
||
transaction.c:89 info : Destroying transaction for subscriber '6215784'
|
||
transaction.c:208 info : Transaction state AT -> IDLE
|
||
cnetz.c:274 info : Entering IDLE state on channel 131.
|
||
telegramm.c:1486 info : RX Level: 96% Jitter: 0.06 Sync Time: 5543.98 (TS 14.00) POSITIVE
|
||
dsp.c:641 info : Switching channel (mode)
|
||
telegramm.c:1484 info : RX Level: 97% Jitter: 0.08 Sync Time: 9333.99 (TS 23.57) Bit errors: 6 POSITIVE
|
||
telegramm.c:1525 notice : Received Telegramm that is not used OgK channel signaling, ignoring! (opcode 22 = AT(V))
|
||
|
||
</pre>
|
||
|
||
|
||
<hr><center>[<a href="index.html">Back to main page</a>]</center><hr>
|
||
</td></tr></table></center>
|
||
</body>
|
||
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|