Could you please check -R option is working as expected ?

xmikos / soapy_power

Obtain power spectrum from SoapySDR devices (RTL-SDR, Airspy, SDRplay, HackRF, bladeRF, USRP, LimeSDR, etc.)

MIT License

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Could you please check -R option is working as expected ? #3

Closed mariocannistra closed 7 years ago

mariocannistra commented 7 years ago

Could you please check the -R option to remove the DC spike in the middle of the FFT ? Plotting the data that I'm collecting during scans I can still see that, despite I have specified the -R option. These are my command parameters:

-r 15M -f 15M:30M -b 2000 -G "LNA=45,TIA=15,PGA=0" -w 30M -t 0.1 -e 900 -R --reset-stream

See an example scan plotted here: https://cloud.githubusercontent.com/assets/1177953/25754297/fb553cee-31be-11e7-9dd3-8dbbd4369a01.png

xmikos commented 7 years ago

It has definitely worked in my tests. But it simply removes FFT bin in DC and interpolates it from closest bins. Maybe --detrend constant could be better option for you?

mariocannistra commented 7 years ago

Thank you. I tried --detrend constant and seen it's removed, but leaves a darker line (lower value in the output compared to bins on both sides): utc20170507115743-mcrao-hf-15 000m-30 000m-b2000-t0 5-glna45tia15pga0-e3m

I also tested using --fft-window boxcar -R and seems to work better, at least for my use case: utc20170507102612-mcrao-hf-15 000m-30 000m-b2000-t0 5-glna45tia15pga0-e30m

I will do more tests when possible since at the moment I'm not sure about the advantages of using different window types. closing the issue / question... Cheers, mario