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RE: AO-51 or ECHO downlink power



Hi Bob, et al!

I have always wondered about the apparent 100% ON time philosophy used on
AO-51. Perhaps after a few years of operating, AO-51 ops might clear up this
questions.

Also, I never did understand why the 7 watt capability was touted but never
used (to the best of my knowledge). The high power was indicated as offering
simple receiving requirements to a wider community not having more
sophisticated setups.

Then too, unlike SO-50 which must be PL'ed on and then timed off, the PL on
AO-51 must serve another purpose (ala squelch) since from what I gather the
transmitters (those selected) on ON all the time and the PL just keys the
modulation.

Just curious...Bill - N6GHz

-----Original Message-----
From: owner-AMSAT-BB@amsat.org [mailto:owner-AMSAT-BB@amsat.org]On
Behalf Of Robert Bruninga
Sent: Thursday, July 20, 2006 11:38 AM
To: amsat-bb@amsat.org; tmcgrane@suffolk.lib.ny.us
Subject: Re: [amsat-bb] AO-51 or ECHO downlink power


>>> McGrane <tmcgrane@suffolk.lib.ny.us> 07/20/06 12:24 PM >>>
>I have a few points regarding the low power downlink of ECHO.......
>A year and a half ago, I proposed...changeing the satellite
>control to allow excess solar power, beyong battery charging,
>to be directed to the transmitters for higher power daylight operation.

I wonder also if the transmitters are on all the time including the 90% of
the time they are not over the 10% of the earth with Ham radio
operators?  I don't know, because when I listen (in the usa) of course
they are always on.  I dont know what they do the other 95% of the
time.  Since there is PL on the uplink, it would seem possible to
have that start a 1 minute time out timer that would key up the TX
while in view of users, and then time out 1 minute after last user?

This would allow a 10dB increase in TX power with no impact on
average power budget.

>I believe one of the intents of echo was to introduce new users to
>satellites and amsat.

Being 10 dB stronger when in view, and Off when no one is in the
footprint  would make it a lot more visible to modest users.
Again, I could be fully wrong and maybe it does only come up on
PL 67.  But I could not find any mode-descriptions on the web
page that gave this kind of detail.  So forgive me for guessing...
or for not finding the right info...

Bob
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