etxbrfa@kklm01.ericsson.se (11/08/88)
It seems as many people out there are interested in laser-rangefinders.
I got lots of answers to my question earlier, and I've done the homework
for this time. Now for todays questions.
If the beam is modulated with a frequency of, say, 10MHz (30 meters), how
can I electronically measure the phase difference between outgoing signal
and reflex. If I use an oscilloscope, it's easy to se how many millimeters
the reflex is from the output and multiplying that with the timebase gives
the time. (And from that ofcource the distance.) But how can this be done
electronically? I suppose the solution is't that difficult, but at least
I don't know how to do it.
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ledge availible in the world.gfv@homxc.UUCP (G.VALVO) (11/10/88)
In article <122@ericom.ericsson.se>, etxbrfa@kklm01.ericsson.se writes: > It seems as many people out there are interested in laser-rangefinders. > I got lots of answers to my question earlier, and I've done the homework > for this time. Now for todays questions. > > If the beam is modulated with a frequency of, say, 10MHz (30 meters), how > can I electronically measure the phase difference between outgoing signal > and reflex. If I use an oscilloscope, it's easy to se how many millimeters > the reflex is from the output and multiplying that with the timebase gives > the time. (And from that ofcource the distance.) But how can this be done > electronically? I suppose the solution is't that difficult, but at least > I don't know how to do it. I don't know if it's actually done this way, but phase comparitors are very common electronic components. They are required for phase locked loops. A (double) balanced mixer will work. The output (after low pass filtering) will be a DC voltage proportional to the phase difference. They key is being able to perform a nonlinear operation. Greg