Some hamradio ax.25 routines for gnuradio
C++ CMake Python C
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Latest commit bcc1d75 Jun 2, 2017 @dl1ksv dl1ksv Merge pull request #9 from 1njected/patch-1
Updated modules path for Kali Linux


gr-ax25 is a small package to deal with ax.25 packet data.

At the moment it contains three blocks

afsk1200  - a variant of the multimon demod_afsk12 decoder adopted to gnuradio (demodulation and decoding)
 The original code requires the signal to be sampled at 22050 Hz. In this variant the samplerate can be set and works at least up t0 48000 Hz.

aprs2inet - assembles an ax.25 frame from an bitstream and converts the frame to internet-format.
 These frames can be fed into xastir via a tcp connection.

ax25decode -  assembles an ax.25 frame from an bitstream and decodes the  frame

1. Dependencies:

- gnuradio
- gr-display ,only if you want to display the decoded text within the flow graph

2. Installation

get the latest code from

The build process is cmake based. So change to the code directory.
$mkdir build
$cd build
$cmake -DCMAKE_INSTALL_PREFIX=<where gnuradio is installed> ../
$make install

After that you'll find a label AX.25 in grc.

3. Example

The example in the apps directory can receive aprs data (144.8 Mhz) or packet radio from the ISS using the fcdproplus.
To run the aprs example you have to run the detectmarkspace block and install it in your grc, first.
If you wish to send the decoded data to xastir you have to enable the path to the tcp sink.
If the tcp sink is enable the flowgraph starts running after a client has connected to the tcp sink.

The example enables the comparison of different afsk decoder and can serve as basis for testing different decoders.

Here is a small example output recorded from ISS ( Timestamp is MESZ )

AFSK1200: fm YU7RD-0 to APRS-0 via RS0ISS-0 UI  pid=F0
=4532.92N/01930.10E-Op.Vlado/QTH:Kula {UISS53}
AFSK1200: fm SP1TMN-6 to CQ-0 via RS0ISS-0 UI^ pid=F0
AFSK1200: fm SQ6OCZ-6 to UQPW44-0 via RS0ISS-0 UIv pid=F0
',W"l .S\]Robert via ISS JO81LC 73 ALL=
AFSK1200: fm OH6MCZ-0 to VSPU56-0 via RS0ISS-0 UIv pid=F0
'1G,l .`/]Op:Petri QTH:Vaasa KP03uc
AFSK1200: fm HB9SKA-0 to APRS-0 via RS0ISS-0 UI^ pid=F0
=4726.07N/00812.00E-Via ISS, 73 de Thomas
AFSK1200: fm DL2YED-6 to APRS-0 via RS0ISS-0 UI  pid=F0
=5138.83N/00711.95E-73 via ISS de Ralph {UISS53}

4. To do

5. Credits

The original code is taken from multimon by Thomas Sailer, HB9JNX