geosapien
Posts: 16
Joined: Fri Nov 23, 2018 7:01 pm

RF Spectrum analyzer to view the VHF/UHF over the air television spectrum

Mon Jan 06, 2020 9:50 pm

I am looking for a way to set up a PI with an RTL-SDR so I can view the OTA TV spectrum. I have configured a PI with GQRX and QSpectrum, but not getting a wide enough view of the spectrum. In order to see an entire channel, I need 6 MHz of BW.
I tried to load Freq Show, but it appears that software was written to output to a 3.5" LCD. I tried to change to code to push out the HMDI output, but could not get it to work.
What I am after is 20 MHZ BW on the display, with no more than a 2 second refresh rate, but at a smaller BW, i would like a faster refresh, like .5 seconds. I feel after watching hours of videos and reading several instructables the limiting factor is the software, and not the PI or RTL.
Any Ideas?

geosapien
Posts: 16
Joined: Fri Nov 23, 2018 7:01 pm

Re: RF Spectrum analyzer to view the VHF/UHF over the air television spectrum

Thu Mar 19, 2020 5:44 pm

Got some free time to work on this...

Loaded a PI 4 with the latest buster distro and installed qspectrumanalyzer again
I then installed all of the back ends that this software supports
I chose the rtl_power_fftw as my back end, and turned the sample rate down pretty low.
I get a decent image with minimal amounts of jitter from the sampling, but still a slow sweep rate

I have moved this project to a jetson nano, and am seeing huge performance improvements.

This will work for audio applications on a pi, but for the broadcast TV spectrum i needed the larger window and faster refresh/sweep. The Jetson will run with rtl's fftw all day long with out an issue on a .5 interval and up to 10 mhz of signal displayed.

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