Rick W wrote: > I don't know enough about ionospheric disturbances to know if you can > only have Doppler (such as polar flutter) without having multipath at > the same time.
The only way that comes to my mind that you can get rid of multipath is by just receiving a single ray. To achieve it, a working frequency for a given path geometry between two stations might be chosen for a limited period. That is tricky and sadly, not practical, being a moving target. The practical solution is to use the Optimum Working Frequency, conventionally 85% of the MUF, but that might allow some multipath to propagate. When you must reach more than one station, at different distances, you certainly must allow multipath to exist as well. > I seems reasonable that you might have one or the other, > but most times (as you have tested) you have some of each. The boundaries between ionospheric regions are always "shaky", and contracting or expanding around the planet, so, most of the time, some Doppler, even slight and slow, is unavoidable. 73, Jose, CO2JA
