300khz Bandwidth limit in waterfall problem

[Greg Newberry]

I recently installed the pre-compiled windows version of GQRX on my windows 10 computer. I got it from Pothosware. Version is 2.14.4-21.

I also installed GPredict. My SDR is an Sdrplay RSP1a, and GQRX recognized it and it works. I can listen to almost anything.

Here is the problem. I only get about 300khz of blue waterfall bandwidth on any frequency. 40 meters 7.150, or 2-meters. 300 khz. Now I'm not talking about zooming in or out on the display. I mean the literal waterfall that turns blue. Zooming works just fine.

So I'm trying to capture NOAA satellite images. I can tune manually to the frequency, say 137.1mhz. But when I use Gpredict to track the satellite and adjust GQRX for the doppler, the receive frequency falls outside of that 300khz waterfall bandwidth. Doesn't matter what sample rate, decimation or FFT size. And this isn't the filter width either. I can adjust that just fine. It is as if the receiver is locked to a 300KHZ bandwidth coming into GQRX.

If I use SDRUno, it work just fine. My waterfall bandwidth changes as you would expect if you change your sample rate.

I removed and re-installed the Pothosware package (which installs GQRX) but no change.

Any thoughts?
Thanks

Greg

WB7DUO

[Simon Kennedy]

Hi Fred

Bandwidth is a product of sample rate and decimation. What have you got these set to in gqrx? 

Run gqrx from the command line and post the output here or a screen shot of the device config would help.

Regards

Simon.

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[Greg Newberry]

Thanks Simon. The sample rate is 2mhz and decimation is none. I've tried sample rates to 10mhz but no difference.

As you can see, the bandwidth of the blue waterfall is roughly 250-300khz. No settings I've tried change this.

Thanks for any input!

Greg

[Simon Kennedy]

It looks like a 300 kHz filter is active before the signal gets to gqrx. Assuming you haven't got anything else in line I blame the RSP1a.

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[Simon Kennedy]

Maybe the Soapy initialisation string is specifying a 300 kHz bandwidth.

[Greg Newberry]

That's exactly what it seems like to me. The RSP1a works as expected with SDRUno and HDSDR. It may be how it was compiled and setup by Pothosware for the Windows 10 platform. I'll keep trying things and hopefully stumble onto something.

Thanks for your help

[Dave B]

"millihertz"?

    Dave G8KBV (I'll get my coat...)

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[Jeff Long]

In this case, use 1536000 for the bandwidth (the next valid value below 2000000).

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[Jeff Long]

Oh, right, in gqrx that would be 1.536 (MHz).

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[Simon Kennedy]

The post at this link describes a similar problem but, sadly, no solution: https://groups.google.com/g/gqrx/c/cxM9N3aJksE?pli=1

To view this discussion on the web visit https://groups.google.com/d/msgid/gqrx/CAC5f9jZ8AT5kSmjc%3D76bbSZrYKf-hhZhpURvV5gz-5hHs3goug%40mail.gmail.com.