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Re: TV satellite measurement of c



depends on what you mean by at home. A fast pulse generator driving a
fast LASER diode, fast photo diode, and a fast scope will do it. Or you
can skip the diode and depending on how fast your other devices use a
reasonable length of cable. Just of the top -- a 30 meters and a 30m Hz
scope and an easy make yourself pulse gen. will do. Another method is
to use an oscillator; look at the beats.

another method is a high speed motor (6 k RPM) driven mirror.


bc

P.s. it's carnivore and echelon that creates the delay


Tucker Hiatt wrote:

I was hoping to be able to use a satellite TV system to measure the
speed of light. When I compare the arrival time of satellite TV
signals with identical (network affiliate) broadcast TV signals, I
measure a consistent time delay of 3.8 seconds for the satellite
signals. If the satellite signals were merely making a single
up-and-down trip to a geosynchronous satellite, I'd expect a MUCH
shorter delay (something like 0.24 seconds).

Does anyone know why the delay is so long? (Does the signal spend 3.5
seconds being "processed"?)

Does anyone have an "at home" method for measuring "c" that I can
share with my students?

Thanks,

- Tucker
--
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Tucker Hiatt, Director
Wonderfest
P.O. Box 887
(39 Fernhill Avenue)
Ross, CA 94957
hiattu00@usfca.edu
415-577-1126 (voice)
415-454-2535 (fax)
http://www.wonderfest.org

Truth is a great flirt. - Franz Liszt
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