An implementation of Analog cellular networks like A-Netz, B-Netz, C-Netz, NMT, AMPS, TACS, JTACS, Radiocom 2000, IMTS, MPT1327, Eurosignal and more http://osmocom-analog.eversberg.eu/
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osmocom-analog/docs/a-netz.html

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<h2><center>A-Netz</center></h2>
<center><img src="a-netz.jpg"/></center>
<p align='justify'>
Now run your base station on channel 30.
Tune the transmitter to 162.050 MHz and the receiver to 157.550.
You should tune the receiver to 164.050 first, to check if you hear the idle signal from the base station.
Then tune to actually uplink frequency 157.550 MHz.
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<font size='4'><pre>
# src/anetz/anetz -k 30
...
anetz.c:170 info : Entering IDLE state, sending 2280 Hz tone.
Base station ready, please tune transmitter to 162.050 MHz and receiver to 157.550 MHz.
on-hook: ..... (enter 0..9 or d=dial)
</pre></font>
<center><img src="a-netz-display.jpg"/></center>
<p align='justify'>
Turn on you phone and wait for it to warm up (requires about half a minute).
Tune the phone to channel 30 and switch on your transmitter for the base station.
The phone should indicate a (green) light, to show idle channel.
If there is no green light, increase the level of your FM signal on the transmitter.
Or if you can't increase the audio level on the transmitter, do it with 'alsamixer'.
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<font size='4'><pre>
anetz.c:244 info : Received 1750 Hz calling signal from mobile station, sending 1750 Hz acknowledge signal.
anetz.c:256 info : 1750 Hz signal from mobile station is gone, stopping acknowledge signal.
call.c:574 info : Incomming call from '' to 'operator'
anetz.c:272 info : Received 1750 Hz release signal from mobile station, sending idle signal.
anetz.c:201 info : Entering IDLE state, sending 2280 Hz tone.
call.c:695 info : Call has been released with cause=16
call disconnected: hangup (enter h=hangup)
</pre></font>
<p align='justify'>
When you pick up the phone, the phone transmits a 1750 Hz calling tone.
On reception, the base station then transmits a 1750 Hz acknowledge ton.
After that the call is establised.
After establishment, you can use the headset, if present, for speech communication with the phone.
On hangup, the phone transmit a 1750 Hz hangup tone.
Then the base station returns to idle again.
Be sure that the phone turns off the transmitter and indicates the (green) light.
</p>
<p align='justify'>
To call to the phone, be sure that your transmitter transmits loud enough to send 4 sine waves at once.
Enter the last 5 digits of the phone's number and press 'd' to dial.
If you listen to the transmit signal, you should hear 4 low pitched tones at once.
The phone should now stop the idle light and indicate an incomming call.
There is no acknowledgement from the phone until you pick up the call.
If the phone does not indicate an incomming call, increase the volume of the transmit signal, but be sure not to overdrive it.
Also be sure that you are actually dialing the right number, so the base station generates the correct paging tones.
</p>
<p align='justify'>
Instead of transmitting all 4 tones at once, they can be transmitted after each other.
Each tone is playes for a short time.
After the last tone has been played, base station starts again with the first tone.
My phone also responds to a call, even if the tones cycle rather than sent simultaniously.
In this case the level of each tone is four times highter (+6 dB).
Add command line option "-P 50" to send each tone for 50 milliseconds.
Try something between 20-100 milliseconds, if the phone still doesn't ring.
</p>
[<a href="index.html">Back to main page</a>]
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