At 09:07 16.2.2014, you wrote:
Satelliitit taitavat olla normaalisti niin pienikokoisia, että niistä ei saa
suoraa heijastusta.
JUUANTEEKSI, TUOSSA muistin vajavaisesti.
Mahdollisen oikaisun varalta lainaan kirjoituksensa tähän.
I apologize for this, but as I gather this
posting is allowed to quote. The following is by Mr Jean-L. Rault::
Hi all
Please be assured that the reception of ground
VHF transmissions reflected by space stations is possible with amateur means.
More than 12 years ago, I tried with Philippe
F6ETI to use the MIR russian space station as a VHF space reflector.
And it worked :o)
Please look at
<http://ph-martin.pagesperso-orange.fr/f6eti/mir/index.htm>http://ph-martin.pagesperso-orange.fr/f6eti/mir/index.htm
for some details (sorry, it's in french).
Doing the same nowadays with FM broadcast
transmitters should be an affordable challenge.
On the negative side:
- FM broadcast uses more bandwidth than we used
for our CW -telegraphy- tests (thus decreasing
the SNR -signal to noise ratio-),
- FM band is generally crowded by local, contiguous and loud transmitters
- FM band uses lower frequencies than the 144 MHz
ham band (thus decreasing the ERS -equivalent
radar surface- of the space target)
- Commercial FM receivers seem to be often less
sensitive than ham radio receivers generally
fitted with LNAs (low noise amplifiers)
On the positive one:
- ISS presents a much larger ERS (equivalent radar surface) than MIR
- FM broadcast transmitters are radiating a much
much higher ERP (equivalent radiated power) than
ham stations (Hundred of kW instead of tens)
IMHO, the key to success for FM space bodies
radio reflections is to precisely determine the
time of occurence of such reflections. We -as
amateurs- have to use specular reflections.This
specular reflections time détermination depends
mainly on the geometry (location of transmitters,
observation location and space reflector trajectory and orientation).
Hope it helps :o)
Jean-Louis F6AGR
Former AMSAT-France president
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