Re: [Discuss-gnuradio] APT signals

[Berndt Josef Wulf]

G'day,

I'm looking for raw data. Don't you use the usrp_rx_cfile.py script to
 capture frequency spectrum?

e.g.: ./usrp_rx_cfile.py -d 32 -f 137.5M

You may need to play with the options -R, -g, -N (subdev, gain and number of
samples) depending on your setup where

-R [A|B]                        site where the tvrx is plugged in
-g <0..115>             gain (default is mid-point @ 58)
-N <positive int>       number of samples (e.g samplerate * record time in sec)

I usually have to specify the frequency and the decimation.

I want to write my own decoder and an image sink to ultimately display the
pictures received and hence audio files want do the trick.

cheerio Berndt

On Saturday 09 December 2006 14:29, Bill Tracey wrote:
> Berndt,
>
> I can grab some APT audio with a USRP and Bob McGwier's rx apt code.    Or
> are you looking for the raw data coming off the TVRF -- could probably do
> that as well but will need some pointers as to how to grab the raw sample
> off the TVRF card -- suppose one just takes the rxapt python code and hacks
> it to dump to a file sink?
>
> I've also got a Hamtronics R139 I can grab audio from -- although it's
> gotten a bit deaf  of late.  Pics from it can be seen @:
> http://oddjob.yi.org:8888/wxpics/index.html
>
> Regards,
>
> Bill
>
> At 10:44 PM 12/8/2006, you wrote:
> >G'day,
> >
> >Ok, let's try it this way:
> >
> >Is there someone with the equipment and time to record APT signals
> >transmitted
> >by NOAA satellites in the 137MHz band? Alternatively, geostationary
> > weather satellites transmit WEFAX pictures at around 1691MHz (Hey, were
> > are the guys that tuned into GPS spectrum which is right next door... :-)
> >
> >I want to demodulate the AM/FM 2400Hz sub-carrier signal and display the
> >image. Currently I'm not in the position to capture the spectrum myself
> > due to lack of equipment but this is about to change.
> >
> >I can provide info on satellite passes and frequencies for your location.
> >
> >cheerio Berndt
> >
> >On Wednesday 06 December 2006 14:20, Berndt Josef Wulf wrote:
> > > G'day,
> > >
> > > Has anyone sampled NOAA or METEOR signals in the 137MHz spectrum which
> > > they wouldn't mind sharing the spectrum data file(s)?