> >> they linearly
> > slewed the transmitter frequency at a given rate and then heterodyned
> > the current =A0tx =A0signal with the reflected signal. The difference i=
n
> > frequency between tx and rx signals gave the time delay and hence
> > distance...


> You can.When I was at university there was a big project that used
> this technique to assist the blind. I wasn't involved but remember
> there were a variety of implementations including a cane and
> spectacles with the transducers attached.

Professor Kay as I recall.
Gargoyle probably knows.


     Russell

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