gr-ais with osmosdr

Christian Gagneraud chris at techworks.ie
Sun Aug 5 18:45:28 UTC 2012


Hi there,

I saw a message in the July archive (I wasn't subscribed yet at that 
date) about updating gr-ais with osmosdr support.
I was working on the same thing recently, so i decided to publish my 
fixes on top of Antoine's one.
The result can be found here:
https://github.com/chgans/gr-ais

I got it working with both an FCD and an RTL:
ais_rx.py --rate 96e3 --gain 30 --error -17 -d -D fcd=0
ais_rx.py --rate 1024e3 --gain 30 --error -110 -d -D rtl=0

Strangely passing freq_err=XX parameter to the source (using -D), 
doesn't work, the use of --error is thus needed (which will do a 
set_freq_corr()).

Antoine, if you want sample file, just let me know.

Nick, are you willing to integrate these changing back in gr-ais, Apart 
from the added automatic decimation filter, the changes are not 
intrusive at all.

The default settings for UHD are 256Khz sampling with decimation filter 
4, with this change, the decimation is one when using FCD (96KHz fixed 
frequency) and 16 for RTL when used at 1.024MHz (this was the minimum 
working frequency for me).
Or maybe would you prefer to allow the user to set it manually, and use 
this technique as a fall back only.

Please let me know what you guys think.

Thx,
Chris

-- 
Christian Gagneraud,
Embedded systems engineer.
Techworks Marine
1 Harbour road
Dun Laoghaire
Co. Dublin
Ireland
Tel: + 353 (0) 1 236 5990
Web: http://www.techworks.ie/




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