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This repository is now obsolete, it's functions are now built-in in TETRA Listener

TETRA Multiframe SDS decoder

This solution provides patches against TETRA Listener and scripts to correctly decode and assemble multi-frame SDS

Architecture

  • Patched tetra-rx writes packets in PCAP format to FIFOs in set directory
  • sds-parser.py reads packets from FIFO pipes, combines them, feeds them through wireshark tetra dissector, combines them into multiframes and parses them
  • Output is given on both stdout and SQLite db file sds.db

Dependencies

  • Install TETRA Listener
  • Have Python 2 and TShark available
  • Run this on Linux machine with /tmp available

Installation

  • Apply patches
    • cd tetra-listener ; git apply tetra-listener.patch
    • cd tetra-listener/osmo-tetra ; git apply osmo-tetra.patch
  • Build tetra-listener again using ./build.sh
  • Run tetra-listener/radio-tetra/tetra.sh
  • Run sds-parser.py -p /tmp/fifos and observe the output

Troubleshooting

I'm not seeing any decoded SDS frames

Check if there are any GSMTAP frames on loopback interface (ie. tshark -i lo)

If there are not, check that

  • you are reading from the FIFO pipes (you have sds-parser.py running with correct arguments), otherwise tetra doesn't decode or send any data
  • you have correctly set TUNE_PPM, TUNE_FREQ variables in radio-tetra/config.sh

Try tuning your SDR using two steps:

  • execute radio-tetra/tetra_cli_pwr.py to get signal strengths on available channels, better signal strength is on top of the list
  • execute radio-tetra/tetra_cli_auto_tune.py X, where X is channel number from 0 to 71, from radio-tetra/tetra_cli_pwr.py output

In tetra.sh output I see number of "0" letters

This means your machine cannot correctly decode all the TETRA streams, try lowering STREAMS in radio-tetra/config.sh

tshark died appears when running sds-parser.py

Probable cause is that tshark doesn't support used filter params. Try editing file config.py, disabling the default tshark_pipe variable, and enabling the other one (which has _element suffixes to filter element names)

Tip

  • You can grep output of sds-parser.py for lines containing ASCII output, to search for text data
    • ie. ./sds-parser.py -p /tmp/fifos | grep "SDS T4 TRANSFER USER DATA TXT"

Example output

Running sds-parser.py correctly, you should see output similar to this (real data removed):

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
RAW> 20:C9:00:00:65:04:9E:FF:FF:F0:61:02:08:00:80:05:05:A1:BD:AB:20:28:20:00:28:00:10:80:00:00:00:00:00:00:
MAC_PDU_CHANNEL_ALLOCATION_FLAG: 0
MAC_PDU_TYPE: 0
MAC_FILL_BIT_INDICATION: 1
MAC_PDU_LENGTH: 25
MAC_PDU_ADDRESS: 101 (TO)
TM-SDU LENGTH: 157 bits
DSDS_DATA_USER_LENGTH_INDICATOR: 64
Debug: D-SDS-DATA RAW:     Ahoj    
Debug: D-SDS-DATA RAW: 82:00:20:01:41:68:6F:6A:C8:0A:08:00:
Debug: D-SDS-DATA BY LEN INDICATOR:     Ahoj
SDS_TYPE_4_PROTOCOL_INDENTIFIER: 130
SDS-TL MESAGE
SDS_TYPE_4_MESSAGE_TYPE: 0
SDS T4 TRANSFER DELIVERY REPORT REQUIRED: 0
SDS T4 TRANSFER SERVICE SELECTION / SHORT FROM REPORT: 0
SDS T4 TRANSFER STORAGE: 0
SDS T4 TRANSFER MESSAGE REFERENCE: 32
SDS T4 TRANSFER TEXT MESSAGE TIMESTAMP USED: 0
SDS T4 TRANSFER TEXT MESSAGE TEXT CODING SCHEME: 1
SDS T4 TRANSFER TEXT MESSAGE TIMESTAMP: None
SDS T4 TRANSFER USER DATA ASCII INDEX: 100
SDS T4 TRANSFER USER DATA LEN: 32
SDS T4 TRANSFER USER DATA TXT: Ahoj
SDS T4 TRANSFER USER DATA HEX: 41:68:6F:6A:
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

Also you can get data from SQLite DB like this:

sqlite3 sds.db "select * from sds"

DB schema configuration is in dbo.py