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<html>
<head>
<link href="style.css" rel="stylesheet" type="text/css" />
<title>osmocom-analog</title>
</head>
<body>
<center><table><tr><td>
<h2><center>Das Datenklo</center></h2>
<center><img src="datenklo.jpg"/></center>
<ul>
<li><a href="#history">History</a>
<li><a href="#howitworks">How it works</a>
<li><a href="#terminal">Setup of a terminal</a>
</ul>
<p class="toppic">
<a name="history"></a>
History
</p>
<p>
geschichte
name
was kann der chip
TBD
</p>
<center><img src="datenklo2.jpg"/></center>
<p class="toppic">
<a name="howitworks"></a>
How it works
</p>
<p>
The program 'datenklo' is an emulator for the original "CCC modem", a building instruction released by the Chaos Computer Club in 1985.
The heart of this software is the AM7911 modem chip emulation.
It modulates digital levels to FSK tones and demodulates FSK tones to digital levels.
A software UART (serial transceiver) converts characters (bytes) into levels and leves into bytes.
The modem chip emulation is linked to sound card via ALSA driver.
The UART is linked to a tty emulation.
The tty emulation uses FUSE, so that the linux kernel provides a virtual serial interface. (/dev/ttyDATENKLO0 by default)
</p>
<p>
* TBD *
</p>
<p class="toppic">
<a name="terminal"></a>
Setup of a terminal
</p>
<p>
* TBD *
</p>
<hr><center>[<a href="index.html">Back to main page</a>]</center><hr>
</td></tr></table></center>
</body>
</html>

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<html>
<head>
<link href="style.css" rel="stylesheet" type="text/css" />
<title>osmocom-analog</title>
</head>
<body>
<center><table><tr><td>
<h2><center>Eurosignal</center></h2>
<center><img src="eurosignal.jpg"/></center>
<ul>
<li><a href="#history">History</a>
<li><a href="#howitworks">How it works</a>
<li><a href="#basestation">Setup of a base station</a>
</ul>
<p class="toppic">
<a name="history"></a>
History
</p>
<p>
Eurosignal (a.k.a Europäischer Funkrufdienst EFuRD) was a paging service in Europe.
It was introduced in 1974 in Germany, 1975 in France and 1985 in Switzerland.
The system was shut down in France and Switzerland in 31. December 1997, in Germany on 1. April 1998.
It did not support any message forwarding.
An incoming call was indicated as a beep (and/or vibration) by the pager.
But up to 4 paging IDs could be assigned to one single device.
The device showed which ID was paged.
</p>
<p>
Paging a subscriber was done via telephone dial up.
The prefix was assigned to large areas having multiple transmitters with the same frequency/channel.
(In Germany were three areas: North, Middle, South)
The suffix (the pager ID) was then encoded into tones and transmitted with up to 2 KW of power.
The pager device decoded the tones and checked if they match with the assigned ID.
Inside the pager were jumpers and later a chip with diodes to match the received tone sequence with the assigned ID.
Up to four numbers were assigned to one pager.
</p>
<p>
One may remember the sound at the beginning of the FM broadcast band:
</p>
<center>Listen to the base station's paging sequences:<br>
<audio src="eurosignal.wav" controls></audio></center>
<p>
Check out <a href="http://www.oebl.de">oebl.de</a> for much more detailed description in German.
</p>
<p class="toppic">
<a name="howitworks"></a>
How it works
</p>
<p>
4 frequencies were used by the system:
</p>
<ul>
<li>Channel A: 87,340 MHz
<li>Channel B: 87,365 MHz
<li>Channel C: 87,390 MHz
<li>Channel D: 87,415 MHz
</ul>
<p>
The caller calls a prefix followed by a 6 digits number.
The system puts the number into a queue, so that simultaneous calls can be handled and paging is performed in series.
</p>
<p>
A train of paging messages are transmitted without interruption.
There are two types of messages: A paging message and an idle message.
Each message was about 8.2 seconds long, divided into a sequence of tones.
</p>
<p>
This is how a paging message looks like:
</p>
<pre class="list">
+---------------+-------+-------+-------+-------+-------+-------+
| Idle | Digit | Digit | Digit | Digit | Digit | Digit |
| Tone | 1 | 2 | 3 | 4 | 5 | 6 |
+---------------+-------+-------+-------+-------+-------+-------+
220 ms 100 ms 100 ms 100 ms 100 ms 100 ms 100 ms
</pre>
<p>
The digit clock is retrieved from the change of tones.
If two subsequent digits are the same, the second digit was replaced by a 'Repeat' digit, so that there is always a change of tone between digits.
The Idle tone resets the receiver register and indicates a new message.
A pager ID '122233' would be transmitted as 1-2-R-2-3-R.
A message is repeated multiple times, depending on the load of the system. (2-5 times ???)
If there is no message to be transmitted, the following idle message is sent.
</p>
<p>
This is how an idle message looks like:
</p>
<pre class="list">
+---------------+-------+---------------------------------------+
| Idle | Digit | Idle |
| Tone | R | Tone |
+---------------+-------+---------------------------------------+
220 ms 100 ms 500 ms
</pre>
<p>
Here is a list of all frequencies used.
The distance between frequencies increases on higher frequencies, allowing simple RC filters to be used to detect the tones.
</p>
<pre class="list">
Digit / Tone | Frequency
--------------+----------------
Idle | 1153.1 Hz
Repeat | 1062.9 Hz
0 | 979.8 Hz
1 | 903.1 Hz
2 | 832.5 Hz
3 | 767.4 Hz
4 | 707.4 Hz
5 | 652.0 Hz
6 | 601.0 Hz
7 | 554.0 Hz
8 | 510.7 Hz
9 | 470.8 Hz
Spare 1 | 433.9 Hz
Spare 2 | 400.0 Hz
Spare 3 | 368.7 Hz
Spare 4 | 339.9 Hz
Spare 5 | 313.3 Hz
</pre>
<p>
The message is amplitude modulated.
The modulation index is 92 %.
</p>
<p>
Alternatively the signal can be transmitted frequency modulated, to reduce interference with TV stations.
The frequency is shifted by 7.5 KHz above or below the actual channel frequency.
The frequency deviation causes a change of amplitude in the demodulator of the pager, so it works as well.
</p>
<p class="toppic">
<a name="basestation"></a>
Setup of a base station
</p>
<p>
Find out what channel your pager can receive and select the same channel on the transmitting side.
Assume that your pager is set to channel B, select channel B:
</p>
<pre>
# src/eurosignal/eurosignal -k B
...
eurosignal.c:290 notice : Created 'Kanal' B
Base station for channel B ready, please tune transmitter and/or receiver to 87.3650 MHz
...
</pre>
<p>
If you don't have a FM transmitter instead of an AM transmitter, tune it 7.5 KHz below or above the indicated channel.
I suggest to use SDR, so check out the SDR page.
Then enter the ID of your pager. You will find it printed on the device and/or on the 18 pin chip inside.
If your pager's ID is 123456, enter it and press 'd' to start paging:
</p>
<pre>
on-hook: 123456 (press d=dial)
mncc_console.c:358 info : Outgoing call to '123456'
call.c:699 info : Received MNCC call from fixed network '' to mobile '123456'
call.c:706 info : Indicate MNCC call confirm towards fixed network
call.c:717 info : Outgoing call from '' to '123456'
eurosignal.c:318 info : Creating call instance to page ID '123456'.
call.c:478 info : Call has been answered by '123456'
call.c:466 info : Indicate MNCC answer towards fixed network
mncc_console.c:206 info : Call connected to '123456'
eurosignal.c:605 info : Station acknowledges, playing announcement.
eurosignal.c:387 notice : Transmitting ID '123456'.
eurosignal.c:387 notice : Transmitting ID '123456'.
eurosignal.c:387 notice : Transmitting ID '123456'.
eurosignal.c:387 notice : Transmitting ID '123456'.
mncc_console.c:388 info : Call hangup
call.c:774 info : Received MNCC release from fixed network with cause 16
call.c:778 info : Call released toward mobile network
eurosignal.c:760 info : Call has been disconnected by network.
</pre>
<p>
In order to receive a paging message, use -R (--rx).
Then the software will decode the received IDs and display them.
</p>
<hr><center>[<a href="index.html">Back to main page</a>]</center><hr>
</td></tr></table></center>
</body>
</html>

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@ -38,6 +38,14 @@
<th>MTS / IMTS (USA / Canada)</th>
<th>AMPS (USA) / TACS (UK / Ireland / Italy)</th>
</tr>
<tr>
<td><img src="eurosignal_small.jpg" title="Eurosignal paging service"/></td>
<td><img src="datenklo_small.jpg" title="The Chaos Computer Club Modem"/></td>
</tr>
<tr>
<th>Eurosignal paging service</th>
<th>The Chaos Computer Club Modem</th>
</tr>
<tr>
<td><img src="tv_small.jpg" title="TV signal generator and transmitter"/></td>
<td><img src="setup_small.jpg"/></td>
@ -92,6 +100,7 @@ Implemented networks:
<li><a href="amps.html">AMPS - Advanced Mobile Phone Service</a> (USA)</li>
<li><a href="tacs.html">TACS / JTACS - Total Access Communication System</a> (UK/Italy/Japan)</li>
<li><a href="radiocom2000.html">Radiocom 2000</a> (France)</li>
<li><a href="eurosignal.html">Eurosignal</a> (Europe)</li>
</ul>
</center>
@ -101,6 +110,7 @@ Additional features:
<center>
<ul>
<li><a href="datenklo.html">Das Datenklo</a></li>
<li><a href="tv.html">Osmo TV</a></li>
</ul>
</center>

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