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| author | Andreas Eversberg <jolly@eversberg.eu> | 2016-05-05 18:31:34 +0200 |
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| committer | Andreas Eversberg <jolly@eversberg.eu> | 2016-05-08 15:49:39 +0200 |
| commit | ba91ee82a77f9357758e64953da57d2a148b30c8 (patch) | |
| tree | 458cf3cbe855ca3d788836de9edd01abfe02fd46 /docs/software.html | |
| parent | 1ce67c14e99134e920d016f7abc167ad8acd4583 (diff) | |
Work on documentation
Diffstat (limited to 'docs/software.html')
| -rw-r--r-- | docs/software.html | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/docs/software.html b/docs/software.html new file mode 100644 index 0000000..53f82c9 --- /dev/null +++ b/docs/software.html @@ -0,0 +1,285 @@ +<html> +<head> +<link href="style.css" rel="stylesheet" type="text/css" /> +<title>osmocom-analog</title> +</head> +<body> +<center><table><tr><td> + +<h2><center>Software usage</center></h2> + +<center><img src="signal.png"/></center> + +<p> +To get a list of all options, run the base station software (E.g bnetz) with no parameter or '-h' or '--help'. +</p> + +<p class="toppic"> +Sound interface +</p> + +<p> +Most machines have only one sound adapter installed. +A second sound adapter is required to talk through the base station to have a conversation. +To get a list of devices, run 'arecord -l'. +This is how it looks, if there are two sound adapters installed: +</p> + +<pre> + +# arecord -l +**** List of CAPTURE Hardware Devices **** +card 0: Intel [HDA Intel], device 0: ALC269VB Analog [ALC269VB Analog] + Subdevices: 1/1 + Subdevice #0: subdevice #0 +card 2: Set [C-Media USB Headphone Set], device 0: USB Audio [USB Audio] + Subdevices: 1/1 + Subdevice #0: subdevice #0 + +</pre> + +<p> +Sound card 0, device 0 is used by default. +Run B-Netz base station on channel 1 to test if your default sound adapter works: +</p> + +<pre> + +# src/bnetz/bnetz -k 1 +... +bnetz.c:268 info : Entering IDLE state, sending 'Gruppenfreisignal' 2 on channel 1. +Base station ready, please tune transmitter to 153.010 MHz and receiver to 148.410 MHz. +To call phone, switch transmitter (using pilot signal) to 153.370 MHz. + +</pre> + +<p> +Alternatively select a different sound adapter. +If you prefer card 2, device 0, add '-d hw:2,0' or '--device hw:2,0' to the command line: +</p> + +<pre> + +# src/bnetz/bnetz -k 1 -d hw:2,0 + +</pre> + +<p class="toppic"> +Basic level adjustment +</p> + +<p> +To adjust input and output levels of your sound card, run 'alsamixer'. +</p> + +<center><img src="alsa.png"/></center> + +<p> +To avoid echo of audio input (mic), mute the input (select item and press 'm'). +We want to capture microphone, but not echo it back to the audio output. +Also we want audio on line/headset output and capture from microphone imput. +Do not use input gain on the microphone. +</p> + +<p> +Now we want to calibrate transmitter and receiver audio level. +Run the B-Netz base station in loopback test mode (-L 2). +Even if you plan to setup A-Netz base station, use B-Netz base station for calibration. +</p> + +<pre> + +# src/bnetz/bnetz -k 1 -L 2 +bnetz.c:268 info : Entering IDLE state, sending 'Gruppenfreisignal' 2 on channel 1. +Base station ready, please tune transmitter to 153.010 MHz and receiver to 148.410 MHz. +To call phone, switch transmitter (using pilot signal) to 153.370 MHz. + +</pre> + +<p> +Tune your transmitter AND reciever to 153.010 MHz. +Press the PTT button on you transmitter and talk into it. +Check if you hear your voice at a normal level from the receiver. +Then connect the audio output (headphone) of your sound adapter to your transmitter, by using a variable resistor. +You should hear now the whistle sound clearly on the receiver, once you turn up the variable resistor. +Adjust the audio output so that the tone is not overdriven, but the volume similar to your voice when you talked into the transmitter. +The sound must be clear without any background noise or distortion. +</p> + +<p> +Now connect the audio input (microphone) to your receiver, by using a variable resistor. +Enable the transmitter. (PTT button) +You should now see the signal beeing decoded by the base station: +</p> + +<pre> + +bnetz.c:474 notice : Received telegramm 'Ziffer 2'. (quality=99% level=133%) +bnetz.c:478 notice : Round trip delay is 0.053 seconds +bnetz.c:474 notice : Received telegramm 'Ziffer 3'. (quality=98% level=133%) +bnetz.c:478 notice : Round trip delay is 0.054 seconds +bnetz.c:474 notice : Received telegramm 'Ziffer 4'. (quality=99% level=131%) +bnetz.c:478 notice : Round trip delay is 0.053 seconds +bnetz.c:474 notice : Received telegramm 'Ziffer 5'. (quality=97% level=130%) +bnetz.c:478 notice : Round trip delay is 0.054 seconds + +</pre> + +<p> +Adjust the input level so that the received signal level is arround 100%. +If the input level cannot be ajusted up to 100%, leave it as it is. +There is an option later in this manual to add RX gain. +The quality should be 90% or better. +Now you have connected the base station to your radio eqipment and roughly adjusted the levels. +For finetuning, refer to each network description. +</p> + +<p> +Finally store the settings using "alsactl store" command. +Do this whenever you want to keep your adjustments. +</p> + +<p class="toppic"> +Channel crossing +</p> + +<p> +By default, the right channel of your sound adapter is used to connect to the radio. +Some adapters have mono input, especially on microphone jack. +In this case you will always receive audio, no matter if you cross the channels or not. +If you cross the channels, the left channel of your sound adapter is used. +I use mono cables with only one channel on the tip of the plug. +My sound adapter uses left channel on the tip, so i need to swap channels. +Use the command line option '-x' or '--cross': +</p> + +<pre> + +# src/bnetz/bnetz -k 1 -x -L 2 +bnetz.c:268 info : Entering IDLE state, sending 'Gruppenfreisignal' 2 on channel 1. +Base station ready, please tune transmitter to 153.010 MHz and receiver to 148.410 MHz. +To call phone, switch transmitter (using pilot signal) to 153.370 MHz. + +</pre> + +<p class="toppic"> +Emphasis +</p> + +<p> +Pre-emphasis is used on the transmitter and de-emphasis is used on the receiver side. +The nature of FM causes noise amplitude to be proportional to the transmitted frequency. +(double frequency = double noise volume) +To compensate this, most FM radios, as well as all analog mobile networks emphasis. +</p> + +<center><img src="emphasis.gif"/></center> + +<p> +As depicted, a frequency of 1000 Hz passes the pre-emphasis without any change. +The double frequency (2000 Hz) is amplified to double amplitude (+6 dB). +The result is that higher frequencies are transmitted with more deviation (louder) than lower frequencies. +On the receiver, the process is reversed. +A frequency of 2000 Hz is lowered down to half of it's amplitude (-6 db), so it becomes the original amplitude again. +</p> + +<p> +Generally a transmitter is doing pre-emphasis for you. +If you are connected directly to the PLL of your transmitter, you will also not have pre-emphasis. +In this case you need to do it inside the base station software. Use the command line option '-E' or '--pre-emphasis': +</p> + +<pre> + +# src/bnetz/bnetz -k 1 --pre-emphasis + +</pre> + +<p> +The receiver is doing the de-emphasis for you. +If you are connected directly to the discriminator of your receiver, you will also not have de-emphasis. +In this case you need to do it inside the base station software. Use the command line option '-e' or '--de-emphasis': +</p> + +<pre> + +# src/bnetz/bnetz -k 1 --de-emphasis + +</pre> + +<p class="toppic"> +RX-Gain +</p> + +<p> +Especially if you use discriminator output, you might have low output voltage. +In my experiments it helps to amplify the amplitude by factor two in order adjust a received signal to 100%. +A gain of 6 dB will amplify the amplitude by factor two. +Also the noise of the sound adapter will be amplified by factor two, but this is not relevant at 16 bit resolution. +Use the command line option '-G 6' or '--rx-gain 6'. +In this example I use both, transmitter and receiver without emphasis and add extra 6 dB gain to the input from the receiver: +</p> + +<pre> + +# src/bnetz/bnetz -k 1 -E -e -G 6 + +</pre> + +<p class="toppic"> +Loopback Test +</p> + +<p> +As used before, the loopback test can be used to verify the signal process, such as level, delay and quality. +</p> + +<p> +If command line option '-L 1' or '--loopback 1' is given, a loopback inside the software is performed. +Also the audio signal is sent to the audio adapter, but not received from it. +This test is used to debug the software. +It can be used to see what the output of an external loop would look like. +</p> + +<pre> + +./bnetz/bnetz -k 1 -L 1 +bnetz.c:351 info : Entering IDLE state, sending 'Gruppenfreisignal' 2. +Base station for channel 1 ready, please tune transmitter to 153.010 MHz and receiver to 148.410 MHz. +To call phone, switch transmitter (using pilot signal) to 153.370 MHz. +bnetz.c:509 info : RX Level: 100% Quality=99 +bnetz.c:524 notice : Received telegramm 'Ziffer 0'. +bnetz.c:528 notice : Round trip delay is -0.048 seconds +bnetz.c:509 info : RX Level: 100% Quality=98 +bnetz.c:524 notice : Received telegramm 'Ziffer 1'. +bnetz.c:528 notice : Round trip delay is 0.000 seconds +bnetz.c:509 info : RX Level: 100% Quality=98 +bnetz.c:524 notice : Received telegramm 'Ziffer 2'. +bnetz.c:528 notice : Round trip delay is 0.000 seconds +bnetz.c:509 info : RX Level: 100% Quality=99 +bnetz.c:524 notice : Received telegramm 'Ziffer 3'. +bnetz.c:528 notice : Round trip delay is 0.000 seconds +bnetz.c:509 info : RX Level: 100% Quality=99 +bnetz.c:524 notice : Received telegramm 'Ziffer 4'. +bnetz.c:528 notice : Round trip delay is 0.001 seconds + +</pre> + +<p> +If command line option '-L 1' or '--loopback 2' is given, an external loopback is performed. +The receiver needs to be tuned to transmitter, so the software receives its own signal. +The received quality level is relevant. It should be not less than 90 for B-Netz. +</p> + +<p> +If command line option '-L 3' or '--loopback 3' is given, the audio from the input is sent back to the output. +It can be used to check a headset. +Everything that is spoken into the microphone should be appear in the headphone. +</p> + +[<a href="index.html">Back to main page</a>] +</td></tr></table></center> +</body> +</html> + + |