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RE: Bounce your signal off Mir (passive satellite)



Jerry

I don't understand where your 60 m/s is coming from.
A 300 Hz Doppler shift should be induced by a 312 m/s target speed
( Mobile radial speed = [Doppler freq * light speed ] / [2 * carrier freq]).
This 312 m/s speed is quite large for a commercial jet.
My friend F8RCI told me that I was listening to parisian UFOs :+))
I apologize for the error I made: the Doppler shifts I measured are
certainly
plus or minus around 150 Hz, i.e. 300 Hz peak to peak, which correspond
to positive or negative 300 knts radial speeds. I'll check tonight the 
real values I observed on my home computer.

73 de Jean-Louis F6AGR

> -----Message d'origine-----
> De: Jerry Muller [mailto:k0tv@gateway.net]
> Date: samedi 22 janvier 2000 18:43
> À: Jean-Louis.RAULT@tcc.thomson-csf.com
> Cc: amsat-bb@AMSAT.Org
> Objet: Re: [amsat-bb] Bounce your signal off Mir (passive satellite)
> 
> 
> Jean-Louis,
> 
>     Airplanes? Sure!
> 
>     Let's look at the doppler Assuming 300Hz doppler would 
> give a speed of
> roughly 2E-6 C or 60 M/sec. Jet aircraft cruse in the 500KT 
> range (about 260
> M/sec), but remember that the doppler you are seeing is the 
> speed component
> in the direction between you and the beacon. The speed 
> component is the
> velocity of the aircraft times the cosine of the angle 
> between your line to
> the beacon and the course of the aircraft. This would seem to 
> indicate the
> course of the aircraft is close to perpendicular to the line 
> between you and
> the beacon. My rough calculations say about 75 degrees. You 
> might want to
> find a pilot and see if there's a preferred route (standard 
> routings that
> Air Traffic Control uses for traffic between cities) has with that
> approximate course somewhere midway between you and the beacon. Bet it
> checks out.
> 
>     Bon chance, (Sorry my French is very rusty.)
> 
>     Jerry, K0TV FN42
> 
> 
> -----Original Message-----
> From: Jean-Louis.RAULT@tcc.thomson-csf.com
> <Jean-Louis.RAULT@tcc.thomson-csf.com>
> To: amsat-bb@AMSAT.Org <amsat-bb@AMSAT.Org>
> Date: Friday, January 21, 2000 7:27 AM
> Subject: RE: [amsat-bb] Bounce your signal off Mir (passive satellite)
> 
> 
> >I leave in a valley (the name of my street is Valley Road!)
> >and am definitely NOT in line of sight of a 144 MHz beacon which
> >is located at about 280 miles from home.
> >More than 10 times per hour, the signal becomes readable
> >for a few minutes, with a nice Doppler effect (shifting from + 300 Hz
> >down to - 300 Hz).
> >The same phenomenon occurs with a short waves broadcast transmitter
> >located about 150 miles from home. The 21 MHz ground wave is just
> >readable but many + or - 40 Hz Doppler shifted strong sigs appear.
> >I use the Spectrogram FFT software to clearly analyse
> >and display the echoes. (Bmp waterfall pictures showing nice 
> "S shape"
> >records are  available on request).
> >Where do these echoes come from ? From the airplanes flying in
> >the Paris area.
> >I have been trying "MIR bouncing" for more than one year 
> now, but with no
> >success at all. For theses tests, I'm trying to listen to the VHF
> transmissions
> >of a french VHF transatlantic test beacon which beaming west. Beeing
> located east
> >of the beacon, I usually don't receive any direct path 
> signal, but I try
> >to detect MIR echoes. No result ... I have to dig a little bit more
> >on the link budget :+))
> >
> >Cheers
> >
> >Jean-Louis F6AGR
> >
> >> -----Message d'origine-----
> >> De: Robert Rice [mailto:rcrice@netropolis.net]
> >> Date: vendredi 21 janvier 2000 04:34
> >> Cc: amsat-bb@AMSAT.Org
> >> Objet: Re: [amsat-bb] Bounce your signal off Mir (passive 
> satellite)
> >>
> >>
> >> In a very small way, I've done this terresterially.
> >>
> >> For some time several years ago I accessed a packet node that
> >> was directly
> >> east of me,  but blocked by many buildings in the medical
> >> center 10 blocks
> >> down the street to the east by pointing my 3 element beam 
> due north at
> >> downtown Houston and doing building bounce.
> >>
> >> Amazed the daylights out of me when I first did it.  Took me
> >> entirely by
> >> surprise... until I thought about it.
> >>
> >> Rob Rice
> >> WB5PKN
> >>
> >>
> >> ----
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> >>
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> >
> 
> 
> 
> 
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