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osmocom-analog
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work on docs

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Andreas Eversberg 2016-10-02 09:01:12 +02:00
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README
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@ -42,3 +42,6 @@ Telecommunication Industry Association for providing TIA/EIA-533 documentation.
"Reproduced under written permission from Telecommunications Industry
Association."
Eric from Smart Card World and Karsten Niehusen from cardomatic.de for
providing memory cards to be programmed for older C-Netz phone.

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docs/amps.html
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@ -23,6 +23,12 @@ History
<p>
*TBD*
The Advanced Mobile Phone Service (AMPS) was an analog cellular mobile phone system developed by Bell Labs.
From 1968 to 1983 the Bell Labs worked out the system, while Motorola was developing the cellular phone.
Dr. Martin Cooper produced the first handheld phone "DynaTAC8000x", the famous Brick Phone.
</p>
<center><img src="amps-dynatac.jpg"/></center>
@ -61,8 +67,8 @@ History
<p>
To reduce radio noise, a syllabic compandor is used on both ends.
This compresses the audio level dynamics by 2.
An audio level of 25% is raised to 50% by the compressor and lowered to 25% by the expandor.
A radio noise floor of 10% would be reduced to 1% by the expandor.
An audio level of 25% is raised to 50% by the compressor and lowered to 25% by the expander.
A radio noise floor of 10% would be reduced to 1% by the expander.
</p>
<p class="toppic">

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docs/nmt.html
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@ -621,11 +621,13 @@ The phone stores the new traffic area and acknowledges the release request.
<p>
Level adjustment:
We see a receive level of around 182%.
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 bust.
Tune your receiver to the donw-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 you previously received from the phone.
In my case I adjust the transmitter to match around 182%. (+- 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 change the traffic area to see the result of your adjustment.
Now, whatever frequency deviation the phone transmits for signaling, so does your base station, because you receive the same level from your base station as you did from the phone.
Use the other variable resistor connecting your receiver, to adjust the volume until the level matches about 100%. (+- 10% is good)
Now, your base station receives the correct frequency deviation as 100%. Also voice levels are now adjusted right.
Switch back the receiver to up-link frequency and change the traffic area to see the result of your adjustment as the phone registers.
</p>
<p>