Re: [Discuss-gnuradio] RDS reception

[Rafael Diniz]

It would be nice, but it could be fixed up and converted to cmake in the
current svn repo also...



> The CGRAN RDS code seems abandoned, I'm thinking about cloning it to
> github so it can be converted to UHD and Cmake and fixed up.
>
> On Fri, Feb 24, 2012 at 1:31 PM,  <address@hidden> wrote:
>> I don't know about having it inside the main codebase, but converting it
>> to
>> use the CMake build system would be good, since it didn't really
>> understand
>> how to place its python files into a filesystem that uses
>> /usr/local/lib64--so I had to move them manually.
>>
>> -Marcus
>>
>>
>>
>> On Fri, 24 Feb 2012 10:23:48 -0800, Rafael Diniz wrote:
>>
>> It would be great to have the rds code inside the gnuradio tree instead
>> of
>> in a separate cgran project!
>> ; )
>>
>> I don't know why, but when I tried the cgran rds code, the grc example
>> worked much better then the python one.
>>
>> Best regards,
>> Rafael Diniz
>>
>>
>>
>> Actually, I'm using the blks2 WBFM block, which I believe is a PLL
>> demodulator.
>>
>> Both of my "test" stations are actually roughly 100km
>> away from me, broadcasting from a high point in the Ottawa Valley.
>>
>> One
>> station comes in about 10dB stronger than the other, although both have
>> an ERP of about 100kW, and both are located on the same transmit tower.
>>
>>
>> I'll send you my 'stuff' once I'm more comfortable with it. The audio
>> quality is actually reasonably good, so I think the FM demodulator
>> portion is just fine.
>>
>> -Marcus
>>
>> On Fri, 24 Feb 2012 11:12:28 -0500,
>> Andrew Davis wrote:
>>
>> I think the problems with SNR is with the FM
>>
>> Demod, my car stereo can
>>
>> get RDS as the station fades 40 miles away,
>>
>> but with my USRP has
>>
>> trouble picking up the stereo pilot from a 50kw
>>
>> station one mile away
>>
>> ( -10dBm ). FM demod is hard for software ( I
>>
>> think GNUradio just uses
>>
>> a zero-crossing detector ).
>>
>> Do you have
>>
>> the code, I would love to test it.
>>
>> On Thu, Feb 23, 2012 at 11:33
>>
>> PM, Marcus D. Leech wrote:
>>
>> I managed to get gr-rds built tonight, and
>>
>> was able to test it planted inside my FM receiver. Even for a local
>> station, there are *lots* of errors, and more distant stations get even
>> more. I'm going to play around a bit with filter bandwidths, etc, to see
>> if I can improve it. Looking at the modulation technique, it's no big
>> surprise--they use a bi-phase baseband coding (basically like
>> differential Manchester), that drives a DSB-SC modulator with a carrier
>> at 57kHz. But that signal is generally about 20dB below the other audio
>> sub-channels on the FM demodulator output. So the SNR is generally
>> *terrible*. I'm rather surprised, after looking at it, that anyone
>> bother deploying RDS. It seems utterly crappy. It's generally broadcast
>> with fairly-low SNR, and there's no FEC built in, only CRC. I re-jigged
>> the XML for the demodulator part so you can reset the demodulator state
>> machine from within a GRC flow-graph (there was a reset() method on the
>> demod, but it wasn't exposed within the XML framework for GRC). Also, I
>> may re-jig the decoder portion--it currently injects decoded frames into
>> a message queue and to stdout. Might be useful to do other things with
>> those messages. Like is there a simple way to have a message dequeuer
>> within a GRC flow-graph so that one could stuff messages into a
>> variable? -- Principal Investigator Shirleys Bay Radio Astronomy
>> Consortium http://www.sbrac.org [1]
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>>
>>
>> Links:
>> ------
>> [1] http://www.sbrac.org
>> [2]
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