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

How much is enough?.



Hi all.
        Re: the power debate ... From http://observations.biz
........................................................................................................................................

POWER. How much is enough? .                       La2qaa Feb 2006.

There could be many answers to that question but the correct one regarding 
amateur satellite communications is ...

"Just enough to maintain effective communications".

For instance, how many people reduce their power as the satellite they're 
operating on approaches TCA ... (time of closest approach) ... a good 
operator will, because they know that the use of excessive power is *not* 
good for the transponder. Case in point. When AO-7 first comes up over the 
horizon you'll probably need "X" amount of power to communicate effectively.

However, after 10-15 minutes, as the range decreases you'll find that a 3dB 
... (50%) ... reduction of power will have no effect whatsoever on the 
signal. A *VERY* sensitive S-meter might show a difference but your ears 
certainly won't.

Hands up those that actually regulate their power to maintain effective 
communications ... (No, I didn't think so) ... you should try it sometime, 
you might get a surprise.

By the way, we do know ... (don't we?) ... why most satellites have a 
beacon?. One of the principal
reason, after telemetry, for a beacon is so that you can regulate your power 
to be consistent with that beacon, it's your reference. No signal should 
EVER be more powerful than the beacon.

Naturally, it will also serve as your propagation reference.
.........................................................................................................................................

For those cases where a beacon isn't operative (read AO-7) you can use 
VE2DWE's sensible suggestion of tuning up and down the band and regulating 
your power to be consistent with known non-alligator stations.

Alligator = all mouth and no ears.

Remember the old adage, if you can't hear them you can't work them.

A decent receive aerial ought to be the most important part of an amateur 
satellite station.

73 John.   <la2qaa@amsat.org>


_______________________________________________
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb



AMSAT Top AMSAT Home