On Wed, 8 Mar 2006 23:19:10 -0000, "Dave" wrote:

what are you mumbling about richard? doppler direction finders operate at
audio frequencies and since the detector and switching system operate from
the same clock they are perfectly accurate... at least as well as you can
calibrate the phase reference between the demodulator and clock.

Hi Dave,

Look at the question again asking for an "FM" receiver. This would
require the action of the discriminator which operates relative to the
LO. Any frequency offset would be a bias, not an audio frequency.
There are two sources in this question, the doppler transmitter, and
the doppler detector. This requires coherence. The magnitude of the
doppler shift has been described all over the map without a strict
correlation to the speeds (or applications) involved. When discussion
devolves to FM detection of a base frequency of 2.5GHz shifting KHz (6
orders of magnitude), the necessary components (for coherence of the
whole system) demand a rather strict requirement for stability and
accuracy for any suitable resolution.

And, of course, some doppler applications can do it with far better
economy - but that wasn't asked for.

73's
Richard Clark, KB7QHC