LRIT decoder


This LRIT decoder is build using the GODIL module with XCS500 FPGA The load also contains HRPT, CHRPT and MHRPT decoders and generators. Software wsat supports now also capturing of this LRIT data.

Switching between decoders is possible in 2 ways:

Decoder description.

The decoder contains the following items: Input signal is a TTL level bit-stream coming from the demodulator (e.g. Costas-loop implementation).

Generator description.

The generator contains following items: The generator is only there to test the data processing; the content is rubbish. It may be refined lateron to generate more VCDU-like data.


The wsat software now just captures the incoming data and writes it to disk. It is stored "packet-aligned", i.e., the first 4 bytes in a file are the sync words and next packets are at multiple of 1024 bytes. Things like packet identification, sequence control etc. are not implemented yet. Also, Reed Solomon processing is not done yet.

Progress decoder

LRIT translation

A program to translate received data into input data for existing software, like xrit2pic, is made. This program works fine on MSG LRIT data, received using a different decoder (SDR) by Martin Blaho.
I am still working for GOES data; although in principle the same format is used the resulting files are different.
First LRIT picture: From SDR LRIT-decoder of Martin Blaho

Bitfiles for XC500 on GODIL 50 board

New in beta 0.4: Works also on inverted data (auto-correction)
VersionContentBit-fileCommand fileComment
beta 0.4 (2011.12) Flash load nfml_decgen.mcs nfml_decgen_flsh.cmd To load into flash
VersionContentBit-fileCommand fileComment
beta 0.4 (2011.12) direct load nfml_decgen.bit nfml_decgen_fpga.cmd To load into FPGA directly, needs to be done each time after power-up

wsat beta version, includes LRIT capture

Linux: wsat_beta.tgz
Windows: setup_wsat_beta.exe