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Required SNR on FM for stereo and mono?
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Does anybody know what SNR levels are needed on FM for mono and stereo?
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It's whatever the listener would find acceptable for listening, so wouldn't it
be the same for stereo and mono ? Personally for me about 60dB for music.
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Alternatively, if you don't know the exact minimum required SNR levels on FM
for mono and stereo, if you know the difference between the two levels that
would still be useful.
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A figure of 18dB sticks in my mind as the difference in audio SNR for
reception of the same signal strength using the Zenith system, but as others
have said tricks like 'hi-blend' help erode this.
Most FM tuners require 60dBuV (1mV) applied to their aerial input for 'full
quieting' on mono (typically about 75ish dB). As Bill says stereo requires
around another 12 dB to deliver the same SNR for stereo ( 72dBuV or 4mV) ?
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I've always worked to the 0dBmV figure given above, but actually I find that
modern FM tuners seem to be able to work tolerably well on much lower signal
levels.
I've carefully looked through all the BBC Eng Info stuff I have about FM
stereo and RDS (1980 to the present) and I can find no mention either of
absolute signal levels or of the differential about which we speak.
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Someone called Mark sent me a copy of a paper about FM from the 1960s
yesterday:
(10 MB)
which you and Mark might find interesting.
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I've just found this page:
and it lists the following two specs as part of a table for a lot of the
tuners listed:
Mono50 1 dBf Mono Sensitivity 50dB Quieting
Ster50 1 dBf Stereo Sensitivity 50dB Quieting
and I've looked at the tuner specs for those listed in the top half of the
page and the difference is always between 18 - 22 dB between stereo and mono
for 50 dB quieting.
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I thought we had established that it was 40db ;)
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Yep, maximum of 40 dB - Croiset said so, so it must be true.
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