thomastoye/dmr-from-scratch

An attempt to decode Digital Mobile Radio (DMR) from scratch in idiomatic Python

Digital Mobile Radio (DMR) from scratch

This project is my attempt to decode Digital Mobile Radio (DMR) from scratch in idiomatic, modern Python. It's optimized for legibility and ease of understanding rather than performance.

Development

$ nix-shell
$ make test

Resources and references

ETSI standard (ETSI TS 102 361):

1. Air interface protocol
2. DMR voice and generic services
3. Data protocol
4. Trunking protocol

Other projects:

• DMRDecode
• mbelib
• dsd
• go-dmr
• dmr_utils3

Assets and example files:

• SDRSharp_20160101_231914Z_12kHz_IQ.wav, source

Implementation of error-correcting codes and checksums

DMR uses a lot of different error-correcting codes and checksums. The description of the FEC and CRC codes used can be found in ETSI TS 102 361-1 Annex B.

• Block Product Turbo Codes (BPTC)
  • BPTC(196,96)
  • Variable length BPTCs
• Rate 3/4 Trellis Code
• Quadratic Residue (16,7,6)
• Golay (20,8,7)
• Hamming Codes
  • Hamming (7,4,3)
  • Hamming (13,9,3), Hamming (15,11,3), Hamming (16,11,4): Used in BPTC
• Reed-Solomon (12,9,4)
• 8-bit CRC, 32-bit CRC, CRC-CCITT, CRC-9, 7-bit CRC, CRC mask for Data Types
• 5-bit Checksum

Currently working on

• Decoding full LCs from voice superframes

dmr-from-scratch's Issues

How it works

Hi, i was looking at the project but i dont know how to use, can someone help me? Thank you ! :)

How to deal with IQ samples?

This program works well, but it can not handle IQ samples directly.
In assets folder, you mention that [SDRSharp_20160101_231914Z_12kHz_real.wav] is made by decoding 4FSK and rrcos. I tried many methods from the Internet, but I still can not make correct real samples from IQ samples.
Could you please tell me how to deal with IQ samples? Appreciate.

error: Django 4.2.4 is not supported for interpreter python 3.9

@thomastoye As soon as I install nix in ubuntu and there after I run this command : - nix-shell. I get this below error :-

error: Django 4.2.4 is not supported for interpreter python 3.9

Please guide further