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Re: UO-14




Hello Bob.

28 Feb 00 09:14, you wrote to Roy Welch:

 BB> Or, in the long run, we should make it part of the satellite operators
 BB> creedo that all satellite operations should be done with "QRP".

We're back to "minimum power necessary" for a reasonable contact, which is
typically in the range of 5 - 20W EIRP for an FM bird (I get in reasonably well
at the 5W mark, with a bit of care).

 BB> THe power to hit any given satellite is basically constant, +/- the
 BB> range difference from the horizon to overhead your QTH which is 10 dB
 BB> plus maybe a few dB of attitude variation.  This relatively constant

If you're lucky, some passes, the variation can be less, others, maybe a little
more.

 BB> power requirement is completely foreign to the experience of most
 BB> Hams
 BB> coming from the terrestrial experience where there is maybe 50 dB or
 BB> more variations in any given path depending on many many factors.
 BB> There, a change in power helps.  In satellite work, it only "helps"
 BB> you to step on someone else.

Quite true, terrestrial paths have wildly varying power requirements due to
distance and terrain factors, while satellites are operating in near free space
conditions.

 BB> As is done in all other satellite services, this minimum power should
 BB> be determined, published and all stations should use that power level.
 BB> This should be part of the satellite operating creed, licensing and
 BB> training.

I don't know about specifying a limit, but operators should be "trained" (read
"strongly encouraged") to keep an eye on their uplink and determine the
"minimum necessary power".

 BB> Similarly, everyone on the ground gets an equal downlink +/- this same
 BB> 10 dB.  Thus everyone gets an equal chance and also the opportunity to
 BB> make sure his station is working correctly.  There are too many
 BB> guys transmitting that dont even hear the satellite!  Amazing.  WHere
 BB> have we failed in operator education and training?

Somewhere.  And it's not hard to hear these downlinks, I do it with a HT!
Perhaps it's stations underestimating their coax losses (I can't use the base
station for satellites due to coax losses, even though they're minor in a
terrestrial situation), and maybe needing to invest in a preamp.

 BB>  The one exception to constant power, is in the case of un-intentional
 BB> uplink jamming from foreign countries that permit terrestrial
 BB> operations in the satellite bands.  Just raising our power to match is
 BB> never going to solve this problem.  These countries must be brought to
 BB> task on the international scale to resolve these violations.  If we
 BB> all continued to use our QRP signals and recorded or took the
 BB> challenge to document and track these illegal operations, this might
 BB> be more useful in the long term...

Hmm, it would take an immense effort to clean up the crud that comes from our
north.  There are so many stations on the satellite band up there that all one
hears is a mass of voices, all jumbled together!

Tony

.. * Dry dock:  A thirsty physician.
--
|Fidonet:  Tony Langdon 3:633/284.18
|Internet: tlang@freeway.apana.org.au
|
| Standard disclaimer: The views of this user are strictly his own.


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