FreeDV demodulator

FreeDV demodulator is a GNU Radio block wrapping the codec2 library freedv_api for receiving digital voice signals.

Input is a stream of modulated siganl data. Output is voice audio.

Parameters

Mode

select one of the 9 signal formats. (depending upon modes enabled in the linked codec2 library)

'1600' Initial mode. 8 kHz in and out.

'700' Deprecated.

700B Deprecated.

2400A Input rate 48 kHz

2400B Input rate 48 kHz

800XA Input rate = Output rate = 8 kHz

700C Input rate = Output rate = 8 kHz

700D Input rate = Output rate = 8 kHz

'2020' low-bitrate - input rate is 4 kHz, Output rate 8 kHz

Squelch threshold

Interleave frames

Squelch Enable

Example Flowgraph

Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI. Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately. The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.

Source Files

C++ files

TODO

Header files

TODO

Public header files

TODO

Block definition

TODO