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From: | Tom Theisen |
Subject: | [Discuss-gnuradio] Measure FM frequency deviation |
Date: | Thu, 25 Feb 2016 05:15:58 +0100 |
Hello everyone,I'd like to measure FM frequency deviation and modulation index of an FM radio broadcast radio station. Unfortunately I can't use the bessel null method as I can't influence the modulation of the transmitter.
I've tried a patched version of rtl_fm [0] with an rtl-sdr dongle to maybe find out how it's done there to implement it in GNURadio. Unfortunately, while working well with narrowband FM it seems to have a very large error when used with wideband FM signals. (I don't know if it's even meant to be used with wide band signals..).
Could you please give me some hints on how I could implement this in GNURadio? Modulation index would be nice to have, but I'm really after the freq. dev.
Many thanks & best regards, Tom Theisen [0] http://comments.gmane.org/gmane.comp.mobile.osmocom.sdr/814Hardware I have: USRP N210, hackRF compatible CCCamp15 badge & various RTL-SDR dongles
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