Very strange "rake" issue

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elekaj34
Posts: 1
Joined: Thu May 05, 2016 1:01 pm

Very strange "rake" issue

Post by elekaj34 » Thu May 05, 2016 1:34 pm

Hello guys,

This is my first post and my firsts experiences with SDR :)
So, at this time, I just want to do as simple as possible !

I've connected my external home TV antenna to my Cinergy TStick RC rev3. This "TV" receiver have on board a RTL2832 and Elonics E4000 chips :)
All my software runs under Ubuntu 14.04 LTS 64bits.

I've successfully installed rtl_power and his others tools -> http://sdr.osmocom.org/trac/wiki/rtl-sdr
and after that I've install QspectrumAnalyser

I can see FM radio stations, but I always have a very strange signal with many peak equally spaced, like a "rake".
You can see that on this screenshoot of a scan from 108 to 200MHz at 50kHz step !.
Image

I'm sure its an harmonic phenomena, but don't see how to fix this issue !

Thanks a lot for your help !

rtlsdrblog
Site Admin
Posts: 2765
Joined: Mon Nov 19, 2012 11:54 pm

Re: Very strange "rake" issue

Post by rtlsdrblog » Fri May 06, 2016 12:14 am

I think what you're seeing is the rolloff from the edges of the RTL-SDR bandwidth. When wide scanning like this you need to use the crop feature of rtl_power. Set the crop to something like 10-20% and the spectrum should look more flat.

Either that or you're simply seeing noise. Try reducing the gain and looking for any sources of noise near your RTL-SDR and antenna.

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