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RE: Question about TV on Ham satellite



Howard,
Not real sure what you are trying to do here, but you talked about 18MHz of
bandwidth required for FM  TV...
Commercial NTSC TV takes 6 MHZ of bandwidth for one signal. The same signal
can be broadcast in about 3 MHz of digital bandwidth if 310m 8VSB MPEG II
encoding is used. Even less can be used if full motion is not needed. The
complete Commercial FM band is only 20Mhz wide with 200Khz spacing and
150-180Khz used for a full fidelity FM channel with subcarriers.  If you are
talking about narrow band voice grade FM you are in the teens.
More info please.
73
Gunther Meisse
W8GSM


-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of Howard Long
Sent: Tuesday, August 20, 2002 11:25 AM
To: amsat-bb@AMSAT.Org
Subject: [amsat-bb] Question about TV on Ham satellite


Folks,

A hypothetical question for you number cruncher / link budget folks out
there...

If one wanted to run a bent pipe FM TV repeater in space, with uplink on
1.2GHz and downlink at 2.4GHz, and the satellite was a LEO, at say 700km
height, with an antenna gain on both 1.2GHz of 6dBi, and a downlink power of
20W EIRPc .

(a) what kind of EIRP would one need on the uplink, and
(b) what size of dish would one need on the downlink?

I think FM TV bandwidth is normally of the order of 18MHz, but the L band
uplink bandplan only caters for 10MHz, so I'd guess we'd have to squeeze
this.

I remember the SUNSAT had a PAL TV downlink on S band - anyone know what
sort of equipment was required to receive this at various P#'s?

http://sunsat.ee.sun.ac.za/media1.htm

http://esl.ee.sun.ac.za/~lochner/sunsat/modes.html

[There's no hidden agenda here, just interested on how you work this out].

73 Howard G6LVB


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