As of GQRX-2.5.3, digital speech decoding finally works for me

[Roger X]

As of gqrx-2.5.3, digital speech decoding seems to be working far better then gqrx-2.5.

Shrugs, thought I had the gqrx latest version and was having difficulties apparently tuning or acquiring the right signal.

I have a RTL2832U, and the only other option besides moving from gqrx-2.5 to gqrx-2.5.3, was resetting the input sample rate from 960000 or 1000000, to 1024000. (ie. Similar to SDSharp 1.024 MSPS)

It could be, resetting to the proper Input Sample Rate provided a signal with the proper sample rate for proper decoding, or something in between the versions hindered digital decoding.

[Roger X]

Everything (software wise) is starting to just work for me.  I'm not sure if any (or some or all) of the following contributed:

1) Using CVS/SVN/GIT dsd might have pulled in some working changes,

2) Finally augmenting the proper exact Frequency Correction PPM value (ie. One value off, and everything is inaudible.),

3) Setting the proper gain level (ie. Again, one or two values off and nothing but inaudible sounds.), or

4) Sun flare activity has subsided with the Moon being in proper alignment, along with the fog lifting and all of the neighbor's generators are now running full speed and providing adequate EMF for my antennas.  (ie. Shrugs.)

RTL SDR rtl_fm piping to dsd is also amazingly working (although still slightly garbled on distant transmissions whereas a normal hardware receiver can receive just fine), after using rtl_power to find optimal values.  Albeit, RTL SDR is still not as good as GQRX, with SDSharp providing a superior signal clarity and signal strength.

[Alexandru Csete]

If you are using FM demodulator with som digital decoder at the audio
end, be sure to switch FM deemphasis off, otherwise it will act as a
low pass filter, which will most likely decrease the SNR.

Alex

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[Roger X]

On Sunday, February 21, 2016 at 3:07:04 PM UTC-5, Alexandru Csete wrote:

If you are using FM demodulator with som digital decoder at the audio
end, be sure to switch FM deemphasis off, otherwise it will act as a
low pass filter, which will most likely decrease the SNR.

Alex

 
My thoughts exactly too (concerning filters for anything) until I used rtl_power, and found the signal dB levels increased more so with with "-F" than without.

Shrugs. Although I did perform several rtl_power tests, I haven't performed a series of redundant tests to rule out fluctuations with the orbits of the Sun and Moon, and human error on my part.