Re: [Discuss-gnuradio] RDS reception

[Brian Padalino]

On Fri, Feb 24, 2012 at 2:58 PM, Philip Balister <address@hidden> wrote:
> On 02/24/2012 02:45 PM, Rafael Diniz wrote:
>> It would be nice, but it could be fixed up and converted to cmake in the
>> current svn repo also...
>
> But most of us have forgotten how to use subversion :)

For those who want to have their cake and eat it too:

    http://subgit.com/

Brian

> Philip
>
>>
>>
>>
>>> 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]
>>>> _______________________________________________ Discuss-gnuradio mailing
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>>>>
>>>>
>>>>
>>>> Links:
>>>> ------
>>>> [1] http://www.sbrac.org
>>>> [2]
>>>> mailto:address@hidden
>>>> [3]
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>>>> [4]
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