the answer is... it depends. most cheap ham style doppler direction finders
with electrically rotated arrays may have trouble locking on to the doppler
shift if it is modulated in some ways. modulation frequencies that cause
phase shifts near the simulated rotatation frequency will be worst as they
will likely be detected by the simple audio phase detector as the doppler
signal and throw it off. if you use a better demodulator that is matched to
the type of signal you are tracking and still can produce an output that is
locked to the phase of the rotating array then it will work. this means if
it is a wideband digital signal you will have to lock on to the base signal
and still differentiate the rotation caused phase shift on top of it... not
always an easy job.

"mazerom" wrote in message
ups.com...
thanks for your comprehensive knowledge.
i intend to make my signal source stationary and would like to emply a
rotating/switching antenna to produce the doppler shift..based on your
explanation,it wont matter what type of signal my source is whether
digital or pure CW signal.assuming a GFSK signal or spread
spectrum(FH), a "reliable" doppler shift will be measured...any
objection or comment sir?

thanks