On Wed, Nov 9, 2016 at 3:16 PM, Cinaed Simson <[email protected]> wrote:
> > In the NBFM receive block, try reducing Tau to 50u, and Max deviation to > 4k. > > (to the hackrf-dev list this time) Thanks, Cinaed! Playing around with max deviation in particular helps with reception quality, for the one good recording (see below). I wasn't hearing anything but noise out the audio sink even eyeballing it on the FFT plot, the signal is 20dB over the noise floor. So I added a file sink, saved a few seconds of the 2.4Msps complex data output of the DC blocker (so almost directly out of the osmocom source). I then used a file source instead of the osmocom source -> DC blocker, and the result is loud and clear audio. Even more puzzling is it only did it once. I collected several more recordings at 2.4Msps but they do not play back audio. Only the first recording produces audio. They all show a strong 20dB signal in the FFT plot and waterfall. My grc file is attached. Possibly a lack of precision on frequency? I tried setting the tune_offset to values from 598e3 to 654e3, which has the normal effect on the first recording, but only static on the subsequent recordings. I would like to add a "sync block," (is that the right term?) so that the graph only plays back at real time, to make it easier to change tuning parameters while playing back a recording. Any tips on how to do that? The attached grc plays back at real time but buffers a lot of audio at the audio sink so that changing things like tune_offset cannot be heard for about 2 sec.
filesource.grc
Description: Binary data
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