Hi, At first I reported this bug at Gqrx mailing list: https://groups.google.com/forum/#!topic/gqrx/pVea3JObMLw , then Csete mentioned that Gqrx uses gr-osmosdr source, while I'm using gr-uhd source. Then I tried it again using osmocom source, then that weird center frequency noise appears again. I've attached several screenshots and GRC flowchart that I used to reproduce this bug (it uses gr-fosphor). Maedhros_008.png is the screenshot of gr-fosphor displaying the correct UHD: USRP source, with all of FM broadcast radio visible, while Maedhros_011.png is the gr-fosphor showing the output of osmocom source, with this big ~2MHz spike at center frequency, and all of those FM broadcast radio are not visible. I'm using Arch Linux with gnuradio, gr-fosphor, and gr-osmosdr compiled from source using makepkg/pkgbuild system, and libuhd 3.10.2.0-3