Re: [Discuss-gnuradio] NOAA Weather Radio receiver flowgraph

[Andy Walls]

On Sat, 2016-11-05 at 14:12 -0400, Andy Walls wrote:
> Someone on IRC had asked about building a NOAA Weather Radio (NWR)
> receiver flowgraph for an RTL-SDR.
> 
> Since I had time, and no chores :), on my weekend, I came up the
> attached flowgraph that handles the WX1-WX7 using an RTL-SDR.  
> 
> It doesn't do the digital decoding of the NWR Specific Area Message
> Encoding (SAME) data.  Also, since the WX stations are a continuous
> broadcast, there is no squelch and no volume control.
> 
> However, the flowgraph does have automatic frequency control (AFC) to
> track with crummy RTL-SDR units, like mine, that are off frequency and
> drift around.
> 
> Regards
> -Andy

"Now with more of the SAME!"

Here's a version that adds a SAME demodulator that finds the 16 byte
SAME preambles and dumps out the 4 bytes that follow the preamble (but
bit reversed, sorry).

The SAME demodulator is missing AGC and a channel equalizer at the
moment.  I'd need real world signals to get properly tweak versions of
those blocks in place.

The demodulator does work against a test SAME audio file injected into
the demodulator.  I'll have to wait 4 weeks for the scheduled monthly
test SAME/EAS signal, to check it against real OTA signals.  (Our weekly
test around here is done at a randomly selected time.)

Regards,
Andy

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nwr.grc
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