[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Satellite ranging



On 2005 Oct 09 Andrew Rich wrote:

> Has anyone done ranging experients, using a two channel CRO and sending a
> signal via a satelite and working out
> the slant range from delay ?

Satellite Ranging
-----------------
Yes. All Amsat P3 satellites had/have ranging capabilities.  Either the flight
computer could regenerate and return a 400 bps signal, or a transponder
could return anything.  The resultant range measurements were used to
determine the satellite's orbit, and will do so again for P3E.

When AO-40 was working you could send pulses through the transponder, and
watch the changing delay.  Pulse-at-a-time measurements are of course noisy,
and you can do far better by sending a rapid stream of pulses.  These can be
faster that the round-trip time allows if you make the pulses a unique stream
of +pulses and -pulses, which manifests itself as a quasi-random data stream.
With this you can, with suitable mix of hardware and software, get both
uplink pulses and downlink pulses "into" a computer and do all the time to
range range conversion automatically to remarkable accuracy (sub km).

An article about this is at:

  http://www.amsat.org/amsat/articles/g3ruh/123.html
  
Hope useful.

73 de James G3RUH  - (AO-10), AO-13 and AO-40 command station

-- 
==========================================================================
    James R Miller      WWW/PGP:     http://www.jrmiller.demon.co.uk/
  Cambridge, England   Stardate:        2005 Oct 09 [Sun] 1902 utc
==========================================================================
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home