How to do AX25, AFSK, DTMF, POCSAG and PSK demodulation on Linux.
(RTL 2832U receiver) Where can I get a RTL dongle http://www.giga.co.za
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| RTL 2832U |
AX.25 (https://github.com/EliasOenal/multimon-ng/blob/master/README.md)
- 1200 Baud AFSK
- 2400 Baud AFSK (2 variants)
- 4800 Baud HAPN
- 9600 Baud FSK (G3RUH)
- 512 Baud
- 1200 Baud
- 2400 Baud
- DTMF
- ZVEI
- SCOPE
1) Download the following Library by using git
git clone https://github.com/EliasOenal/multimon-ng.git
cd to the multimon directory
cd multimon-ng
run the command make
mkdir build
cd build
qmake ../multimon-ng.pro
make
sudo make install
If you want to get this working on Raspberry pi you need to use the following
qmake --version qmake: could not exec '/usr/lib/x86_64-linux-gnu/qt4/bin/qmake': No such file or directory
alias qmake="$(find /usr -name qmake | grep qt5)"
qmake --version QMake version 3.0 Using Qt version 5.3.2 in /usr/lib/x86_64-linux-gnu
Command line options. (here is the help file) multimon-ng [options] [input_file]
sudo sudo multimon-ng -h
multimon-ng (C) 1996/1997 by Tom Sailer HB9JNX/AE4WA
(C) 2012-2014 by Elias Oenal
available demodulators: POCSAG512 POCSAG1200 POCSAG2400 FLEX EAS UFSK1200 CLIPFSK FMSFSK AFSK1200 AFSK2400 AFSK2400_2 AFSK2400_3 HAPN4800 FSK9600 DTMF ZVEI1 ZVEI2 ZVEI3 DZVEI PZVEI EEA EIA CCIR MORSE_CW DUMPCSV SCOPE
Usage: multimon-ng [file] [file] [file] ...
If no [file] is given, input will be read from your default sound
hardware. A filename of "-" denotes standard input.
-t <type> : Input file type (any other type than raw requires sox)
-a <demod> : Add demodulator
-s <demod> : Subtract demodulator
-c : Remove all demodulators (must be added with -a <demod>)
-q : Quiet
-v <level> : Level of verbosity (e.g. '-v 3')
For POCSAG and MORSE_CW '-v1' prints decoding statistics.
-h : This help
-A : APRS mode (TNC2 text output)
-m : Mute SoX warnings
-r : Call SoX in repeatable mode (e.g. fixed random seed for dithering)
-n : Don't flush stdout, increases performance.
-e : POCSAG: Hide empty messages.
-u : POCSAG: Heuristically prune unlikely decodes.
-i : POCSAG: Inverts the input samples. Try this if decoding fails.
-p : POCSAG: Show partially received messages.
-f <mode> : POCSAG: Disables auto-detection and forces decoding of data as <mode>
(<mode> can be 'numeric', 'alpha' and 'skyper')
-b <level> : POCSAG: BCH bit error correction level. Set 0 to disable, default is 2.
Lower levels increase performance and lower false positives.
-o : CW: Set threshold for dit detection (default: 500)
-d : CW: Dit length in ms (default: 50)
-g : CW: Gap length in ms (default: 50)
-x : CW: Disable auto threshold detection
-y : CW: Disable auto timing detection
Raw input requires one channel, 16 bit, signed integer (platform-native)
samples at the demodulator's input sampling rate, which is
usually 22050 Hz. Raw input is assumed and required if piped input is used.
how to decode a wav file
sudo ./multimon-ng -s SCOPE -t wav /tmp/message.wav (to read wav file) How to convert a wav file to row file using sox sudo sox foo.wav foo.raw
Now we want to take the received signal from rtl_fm and pyp it to the multimon
Create a fifo Pyp
Command line options. (here is the help file) multimon-ng [options] [input_file]
sudo sudo multimon-ng -h
multimon-ng (C) 1996/1997 by Tom Sailer HB9JNX/AE4WA
(C) 2012-2014 by Elias Oenal
available demodulators: POCSAG512 POCSAG1200 POCSAG2400 FLEX EAS UFSK1200 CLIPFSK FMSFSK AFSK1200 AFSK2400 AFSK2400_2 AFSK2400_3 HAPN4800 FSK9600 DTMF ZVEI1 ZVEI2 ZVEI3 DZVEI PZVEI EEA EIA CCIR MORSE_CW DUMPCSV SCOPE
Usage: multimon-ng [file] [file] [file] ...
If no [file] is given, input will be read from your default sound
hardware. A filename of "-" denotes standard input.
-t <type> : Input file type (any other type than raw requires sox)
-a <demod> : Add demodulator
-s <demod> : Subtract demodulator
-c : Remove all demodulators (must be added with -a <demod>)
-q : Quiet
-v <level> : Level of verbosity (e.g. '-v 3')
For POCSAG and MORSE_CW '-v1' prints decoding statistics.
-h : This help
-A : APRS mode (TNC2 text output)
-m : Mute SoX warnings
-r : Call SoX in repeatable mode (e.g. fixed random seed for dithering)
-n : Don't flush stdout, increases performance.
-e : POCSAG: Hide empty messages.
-u : POCSAG: Heuristically prune unlikely decodes.
-i : POCSAG: Inverts the input samples. Try this if decoding fails.
-p : POCSAG: Show partially received messages.
-f <mode> : POCSAG: Disables auto-detection and forces decoding of data as <mode>
(<mode> can be 'numeric', 'alpha' and 'skyper')
-b <level> : POCSAG: BCH bit error correction level. Set 0 to disable, default is 2.
Lower levels increase performance and lower false positives.
-o : CW: Set threshold for dit detection (default: 500)
-d : CW: Dit length in ms (default: 50)
-g : CW: Gap length in ms (default: 50)
-x : CW: Disable auto threshold detection
-y : CW: Disable auto timing detection
Raw input requires one channel, 16 bit, signed integer (platform-native)
samples at the demodulator's input sampling rate, which is
usually 22050 Hz. Raw input is assumed and required if piped input is used.
how to decode a wav file
sudo ./multimon-ng -s SCOPE -t wav /tmp/message.wav (to read wav file) How to convert a wav file to row file using sox sudo sox foo.wav foo.raw
Now we want to take the received signal from rtl_fm and pyp it to the multimon
Create a fifo Pyp
sudo mkfifo soundfifo.raw
ls -al
prw-r--r-- 1 anton anton 0 2013-05-07 22:35 soundfifo.raw
You will see its not a normal file its got a prw in front of the file definition when you list the files.
Lets get multimon to start receiving audio from soundfifo.raw pyp.
sudo multimon-ng -a AFSK1200 -a SCOPE -t raw soundfifo.raw
And now send the audio from rtl_fm to the soundfifo.raw
Decoding live data from rtl receiver. (Tuning receiver to 144.800 Mhz packet frequency and demodulate that to 22.05kHz audio)
sudo rtl_fm -f 144800000 -s 22050 ./soundfifo.raw (read my section on rtl if you want to install rtl utilities)
You should then see the scope screen below.
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| Multimon Scope Display |
And your afsk1200 decoding will start in console and the scope display will show your audio.
Here is an example of hot to decode directly from rtl dongle
sudo rtl_fm -d0 -f 144800000 -s 22050 - | multimon-ng -a AFSK1200 -t raw /dev/stdin
Hope this help...REF: www.baycom.org/~tom/ham/linux/multimon.html, http://www.youtube.com/watch?v=GBmli8Vflig and http://www.ultratechie.com/2012/10/pigate/
https://github.com/EliasOenal/multimon-ng/blob/master/README.md
