Reply to post: Re: dabshite

Analogue radio given 10-year stay of execution as the UK U-turns on DAB digital future

AlbertH

Re: dabshite

An FM stereo channel is 150kHz wide - 75kHz either side of the carrier. There are three principal components - sum (L+R - mono) received by mono receivers, difference (L-R) which is modulated on to a 38 kHz-centred double-sideband-suppressed-carrier sub-carrier, and a 19 kHz pilot tone to indicate the presence of stereo and to provide the 38 kHz to re-insert to demodulate the difference component. There is a fourth component these days, another DSSC signal centred on 57kHz which carries the RDS data stream.

For its day, Zenith-GE multiplex stereo (that's what it's called, folks) was a pretty nifty way of retaining compatibility with existing mono radios, and conveying two good quality audio channels (albeit with only 15kHz top end). It's pretty wasteful of bandwidth, but there's a hell of a lot of "plant" about and endless receivers for it in the hands of the public. When done properly, it can sound wonderful.

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