mirror of https://gerrit.osmocom.org/osmo-tetra
111 lines
4.0 KiB
Plaintext
111 lines
4.0 KiB
Plaintext
This is a modified version of osmo-tetra (original README contents are a
|
|
few lines below).
|
|
|
|
This version is patched to work with telive - a program for live listening
|
|
of tetra traffic and recording it, displaying network data etc.
|
|
|
|
The most important changes are:
|
|
- support parsing of SDS messages (text messages similar to SMS), including some location protocols
|
|
- support parsing of D-SETUP, D-RELEASE, D-NWRK-BROADCAST
|
|
- sending of data and voice traffic via UDP (for consumption with telive or some other program)
|
|
- incorporate float_to_bits into tetra-rx
|
|
- implement a crude AFC into tetra-rx and float_to_bits (enables the signal to be less precisely tuned)
|
|
|
|
For more info about osmo-tetra-sq5bpf and telive:
|
|
|
|
Main docs (read this first!): https://github.com/sq5bpf/telive/raw/master/telive_doc.pdf
|
|
Telive repository: https://github.com/sq5bpf/telive
|
|
Modified osmo-tetra: https://github.com/sq5bpf/osmo-tetra-sq5bpf
|
|
Script to automatically download/compile/install the acelp codec: https://github.com/sq5bpf/install-tetra-codec
|
|
Forum thread: http://forums.radioreference.com/voice-control-channel-decoding-software/302347-tetra-decoding.html
|
|
Tutorial: http://www.rtl-sdr.com/rtl-sdr-tutorial-listening-tetra-radio-channels/
|
|
|
|
What follows is the original content of the README file:
|
|
|
|
TETRA MAC/PHY layer experimentation code
|
|
(C) 2010-2011 by Harald Welte <laforge@gnumonks.org>
|
|
======================================================================
|
|
|
|
This code aims to implement the sending and receiving part of the
|
|
TETRA MAC/PHY layer.
|
|
|
|
If you read the ETSI EN 300 392-2 (TETRA V+D Air Interface), you will
|
|
find this code implementing the parts between the MAC-blocks (called
|
|
type-1 bits) and the bits that go to the DQPSK-modulator (type-5 bits).
|
|
|
|
It is most useful to look at Figure 8.5, 8.6, 9.3 and 19.12 in conjunction
|
|
with this program.
|
|
|
|
You will need libosmocore (http://bb.osmocom.org/trac/wiki/libosmocore) to link.
|
|
|
|
|
|
== Demodulator ==
|
|
|
|
src/demod/python/cpsk.py
|
|
* contains a gnuradio based pi4/DQPSK demodulator, courtesy of KA1RBI
|
|
src/demod/python/tetra-demod.py
|
|
* call demodulator on a 'cfile' containing complex baseband samples
|
|
src/demod/python/usrp1-tetra_demod.py
|
|
* use demodulator in realtime with a USRP1 SDR
|
|
src/demod/python/usrp2-tetra_demod.py
|
|
* use demodulator in realtime with a USRP2 SDR
|
|
|
|
The output of the demodulator is a file containing one float value for each symbol,
|
|
containing the phase shift (in units of pi/4) relative to the previous symbol.
|
|
|
|
You can use the "float_to_bits" program to convert the float values to unpacked
|
|
bits, i.e. 1-bit-per-byte
|
|
|
|
|
|
== PHY/MAC layer ==
|
|
|
|
=== library code ===
|
|
|
|
Specifically, it implements:
|
|
lower_mac/crc_simple.[ch]
|
|
* CRC16-CCITT (currently defunct/broken as we need it for
|
|
non-octet-aligned bitfields)
|
|
lower_mac/tetra_conv_enc.[ch]
|
|
* 16-state Rate-Compatible Punctured Convolutional (RCPC) coder
|
|
lower_mac/tetra_interleave.[ch]
|
|
* Block interleaving (over a single block only)
|
|
lower_mac/tetra_rm3014.[ch]
|
|
* (30, 14) Reed-Muller code for the ACCH (broadcast block of
|
|
each downlink burst)
|
|
lower_mac/tetra_scramb.[ch]
|
|
* Scrambling
|
|
lower_mac/viterbi*.[ch]
|
|
* Convolutional decoder for signalling and voice channels
|
|
phy/tetra_burst.[ch]
|
|
* Routines to encode continuous normal and sync bursts
|
|
phy/tetra_burst_sync.[ch]
|
|
|
|
|
|
=== Receiver Program ===
|
|
|
|
The main receiver program 'tetra-rx' expects an input file containing a
|
|
stream of unpacked bits, i.e. 1-bit-per-byte.
|
|
|
|
|
|
=== Transmitter Program ===
|
|
|
|
The main program conv_enc_test.c generates a single continuous downlinc sync
|
|
burst (SB), contining:
|
|
* a SYNC-PDU as block 1
|
|
* a ACCESS-ASSIGN PDU as broadcast block
|
|
* a SYSINFO-PDU as block 2
|
|
|
|
Scrambling is set to 0 (no scrambling) for all elements of the burst.
|
|
|
|
It does not actually modulate and/or transmit yet.
|
|
|
|
|
|
== Quick example ==
|
|
|
|
# assuming you have generated a file samples.cfile at a sample rate of
|
|
# 195.312kHz (100MHz/512 == USRP2 at decimation 512)
|
|
src/demod/python/tetra-demod.py -i /tmp/samples.cfile -o /tmp/out.float -s 195312 -c 0
|
|
src/float_to_bits /tmp/out.float /tmp/out.bits
|
|
src/tetra-rx /tmp/out.bits
|
|
|