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"Pete KE9OA"
As far as AM receivers, they do not have a deemphasis circuit following the detector. With FM receivers, it is a different story. ___________ But in effect, almost every AM receiver has de-emphasis -- it is the result of the "haystack" amplitude response of their RF/IF circuits driving the 2nd detector. Higher modulating frequencies are rolled off, sometimes very severely. The problem with trying to compensate for it at the AM tx is that the amount needed for "flat" system response varies considerably from rx to rx, and even with carrier frequency. Even so, many MW/SW AM stations do boost their highs, trying to get some of it to pass through the narrowband receivers typically in use these days. RF |