Source: Guest Post: A synchronous detector crash course! | The SWLing Post The linked piece has a very good explanation on how a SD works and where is really shines. Examples of 'selective fading' (multipath) and just plain fading (loss of signal) are shown in both a waterfall display and with audio clips. SD is then examined with the effects on same, complete with examples. This is the only article I've seen online with examples of the audio and waterfall display.. If you are looking for a new SW radio for general coverage listening to SW broadcast stations, IMO, it is well worth the extra $10 to $20 charged for a radio with the SD circuits. (example, a PL 600 and PL 660 - pretty much the same radio, one [the -660] has the SD circuits.) Hambones would rather have bandwidth filters than SD, so you don't see that offered in Amateur Radio Service gear. Offered for your edification.
