Re: Someone explain supressed subcarrier?

Radio Road

Which tuner to get and getting the most from it. Thank God, for the radio!

In Reply to: Someone explain supressed subcarrier? posted by lipmanl on November 15, 2006 at 08:34:46:

The IF circuit job is gain and bandpass filtering for frequency selection, (selectivity), then the detector does the the converison from FM to audio band. The sensitivity to AM is dependent on the detector type. The end of the IF section uses limiters to eliminate the AM, with more care and circuit complexity taken if the detector type is especially sensitive to AM. There are at least 5 different types of detectors that have been used over the years, with names like foster-seeley, ratio detector, quad detector, PLL detector, pulse count detector, etc. For good stereo, the detector needs to have wide bandwidth so as not to roll off the high frequencies where the stereo information is. Typical detectors for stereo use will have flat bandwidths far exceeding 100kHz, and 400KHz is not unusual.
The stereo info is in the 23-53kHz part of the FM signal. The whole signal, 20Hz-53kHz is frequency demodulated by the detector. This is usually called the stereo composite signal, and it also includes the 19kHz pilot. Then it goes to the MPX circuit where stereo is extracted. If you want to know how FM stereo works, there are some good explanations on the net, but can't be done easily in a post. this site takes a good whack at it
http://transmitters.tripod.com/stereo.htm
Bob

Stereo Multiplexing for Dummies (Open in New Window)

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Follow Ups Full Thread

Topic - Someone explain supressed subcarrier? - lipmanl 08:34:46 11/15/06 (5)

Re: Someone explain supressed subcarrier? - BFitz 15:49:08 11/15/06 (4)

Aha, sort of - lipmanl 10:49:34 11/16/06 (3)

yes, ONE of the things that a BIG antenna can do, is improve stereo imaging. - Timbo in Oz 17:54:10 11/16/06 (1)

Re: yes, ONE of the things that a BIG antenna can do, is improve stereo imaging. - BFitz 05:13:01 11/17/06 (0)

Re: Aha, sort of - BFitz 14:55:06 11/16/06 (0)

Follow Ups

Re: Someone explain supressed subcarrier? - BFitz 15:49:08 11/15/06 (4)

Aha, sort of - lipmanl 10:49:34 11/16/06 (3)

yes, ONE of the things that a BIG antenna can do, is improve stereo imaging. - Timbo in Oz 17:54:10 11/16/06 (1)

Re: yes, ONE of the things that a BIG antenna can do, is improve stereo imaging. - BFitz 05:13:01 11/17/06 (0)

Re: Aha, sort of - BFitz 14:55:06 11/16/06 (0)

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