My quest into FM-RDS presented at 44Con 2013

by Oona Räisänen,

Summary : This talk will concentrate on my experiences with FM-RDS (Radio Data System), a digital subcarrier embedded in FM broadcast transmissions, and also cryptanalysis of traffic messages contained therein.
I originally found about the existence of such transmissions in a roundabout way, by using a spectrum analyzer program to examine intermodulation distortion in my radio’s Line Out audio. As it turned out, the inaudibly quiet distortion, probably caused by the radio’s stereo demuxer circuitry, contained all the information needed to decode all RDS data present in the transmission. I will demonstrate the journey I took and give a short introduction to how the data is actually encoded. Live acquisition of local RDS data depending on signal conditions in the premises.