Re: TV satellite measurement of c

[Robert Cohen <Robert.Cohen@PO-BOX.ESU.EDU>]

How about calling someone long distance via satellite and having them try to
count along with you?  If they think they are simultaneous, you will observe
a delay equal to the time required for the signal to go up and back from the
satellite twice.  I've never tried it myself.

____________________________________________
Robert Cohen; rcohen@po-box.esu.edu; http://www.esu.edu/~bbq
Physics, East Stroudsburg Univ., E. Stroudsburg, PA 18301

> -----Original Message-----
> From: Bernard Cleyet [mailto:anngeorg@PACBELL.NET]
> Sent: Tuesday, February 26, 2002 2:12 AM
> To: PHYS-L@lists.nau.edu
> Subject: 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
> > --
> > ***********************************
> > 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
> > ***********************************