TETRA MAC/PHY layer experimentation code ======================================== (C) 2010-2016 by Harald Welte and contributors 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](https://osmocom.org/projects/libosmocore/wiki/Libosmocore) to build this softwar Homepage -------- The official homepage of the project is https://osmocom.org/projects/tetra/wiki/OsmocomTETRA GIT Repository -------------- You can clone from the official osmo-tetra.git repository using git clone https://gitea.osmocom.org/tetra/osmo-tetra There is a web interface at Mailing List ------------ Discussions related to osmo-tetra are happening on the tetra@lists.osmocom.org mailing list, please see https://lists.osmocom.org/mailman/listinfo/tetra for subscription options and the list archive. Please observe the [Osmocom Mailing List Rules](https://osmocom.org/projects/cellular-infrastructure/wiki/Mailing_List_Rules) when posting. Contributing ------------ Our coding standards are described at https://osmocom.org/projects/cellular-infrastructure/wiki/Coding_standards We us a gerrit based patch submission/review process for managing contributions. Please see https://osmocom.org/projects/cellular-infrastructure/wiki/Gerrit for more details The current patch queue for osmo-tetra can be seen at https://gerrit.osmocom.org/#/q/project:osmo-tetra+status:open Demodulator =========== src/demod/python/cpsk.py * contains a gnuradio based pi4/DQPSK demodulator, courtesy of KA1RBI src/demod/python/osmosdr-tetra_demod_fft.py * call demodulator on any source supported by gr-osmosdr (uhd, fcd, hackrf, blaerf, etc.) src/demod/python/simdemod2.py * call demodulator on a 'cfile' containing complex baseband samples src/demod/python/{uhd,fcdp}-tetra_demod.py * use demodulator directly with UHd or FCDP hadware (no gr-osmosdr) 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