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Sync detectors and fading
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Sync detectors and fading
In article . com,
wrote: If the selective fading is as tight as you indicate, then there would be "holes" in the audio spectrum of the recovered AM, much like a comb filter. Sync demod won't fix that problem. But the audio spectrum comes pre-equipped with a lot of holes* so there is some benefit, as sometimes it's unimportant frequencies that are fading out. (*That's why MP3 type psycho-acoustic compression can work). There are too many people that think sync demod will cure everything. It's just not true. Now if you have a nearby signal bleeding into the desired signal, then pick the sideband the furthest away from the interfering signal. Here, sync works great. If you have fading, you can narrow band the signal by using one sideband. It helps a bit, but the signal will still fade. I find that there's a number of signals where (as close as I can get to) sync detection (by zero beating the BFO in SSB mode) cleans up the audio to the point where it's listen-able. Typically, these are weak and fluttery high latitude path signals, Europe to Western North America. Mark Zenier Googleproofaddress(account:mzenier provider:eskimo domain:com) |
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