Re: Broadcast FM subcarrier decoding?

On 3/17/2013 11:32 AM, Robert Nickels wrote: Hi Alan, Depending on where you live, there could be several subcarriers present in addition to the prominent 19 KHz stereo pilot. From your description I'm pretty sure you're referring to Sub Carrier Authorization (SCA) which has been mainly used for background music and an audio book reading service for the blind as well as other voice and data services. SCA uses 67 or 92 KHz subcarriers which can be seen on the composite FM signal. If you have a soundcard with sufficient bandwidth you can send the output of SDR# (in NBFM, 150 KHz mode) to another instance of SDR# *(sound card, DSB mode) using Virtual Audio Cable. My soundcard won't go high enough but here's a set of screen images from a system that can, where the various elements on the upper side of the FM channel center are annotated: http://img208.imageshack.us/img208/5922/fmspectrum.png Another subcarrier is used for RDS (Radio Data System) or RDBS in the US digital data channel which can easily seen at 57 KHz on stations utilizing this service. In the US The arithmetic sum of all multiplex subcarriers may not exceed 20% modulation and different rules apply than for the primary broadcast channel. 73, Bob W9RAN