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I was wondering what the noise of stereo signal come into FM and are any ways to reduce it? Naturally we get out stations in mono mode with practically no noise at all. The best tuners more then 85dB signals to noise ratio – that are very high number and the typical hiss the we get in stereo is not even closed to the electrical signal-to-noise characteristics of out tuner. So, why we even have to have the FM Stereo Noise? Is it the fundamental entity of FM reception of juts bad implementation of some specifics?

I would not consider the minor FM noise is destructive – in fact I kind of like it – it has a slight dithering effect but I still wonder….

In my experience the same stations of excellent reception might have fluctuation on FM stereo noise depending of:

1)  How the station broadcasts
2)  Atmospheric condition
3)  Precision of tuning to the stations
4)  The multipath level
5)  The characteristics of the tuners

If with the first 4 parameters everything is understandable then with the last parameters the things are perplexed. All front ends have own noise capacity but how about the stereo decoders? If I run a tuner in mono and have no FM noise then I presume that my frond end and IF sections are fine. As soon I activate the stereo decoding I get noise – so would it be the stereo extraction itself that screw the things up?

Well, we have a number of different topologies the phase locked loop stereo decoders, the pulse-count stereo decoders   etc. We have integrated devised and discrete stereo decoders. We have tubes, hybrid and SS stereo decoders. They all produce different sound but are they the primary source of the FM noise in stereo? If so then is it possible to make the MPX stereo extractors better in order to have lover FM stereo noise?

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