Are the people here getting lazy or what?
20 seconds with google. But now I know how it works too.
http://www.wadeco.co.jp/pdf/rf-e.pdf

The Micro-Ranger transmits a microwave signal towards the
target with a frequency that increases linearly with time.The
microwave signal transmitted at time, t1, with frequency, f1, is
reflected by the target and received by the antenna at time, t2.
{in the case of a satellite, the 'reflector' is a 'bent pipe'
amplifier}.

The total time to travel to and from the target is .t. The
transmitted frequency increases to f2 at time, t2. The difference
in frequency, .f, between the transmitted and reflected waves
is proportional to the distance, d, to be measured.The Micro-
Ranger mixes the transmitted and reflected signals together to
extract the difference in frequency. This signal is analysed by a
FFT (Fast Fourier Transform) analyser to output a distance
signal.This is called the FM-CW method and is suitable for
improving the accuracy of distance measurements.


R

rad0DW wrote:
> So anyway,
>
> How do microwave rangefinders work?
>
> Thanks
>
> My only experience is with the ultrasonic and LED hobby stuff.

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