[amsat-bb] PSAT - power requirements

[Robert Bruninga]

>
> > WB4APR recommends no more than 25 watts.
>
That was the design goal, but until we get more experience, we wont know
for sure.  But since everyone can see their own downlink just like everyone
else can see it, it should be no problem adjusting for minimum uplink power.

 But with any shared transponder it can also become an arms race.  As one
person increases power it drives the AGC down and everyone else goes down,
so they also increase power and this just keeps going until the AGC is
maximally tightened and everyone is transmitting max power and everyone is
weak.

What we really need (BEFORE this happens) is for everyone to give us
feedback as to the minimum power they needed to maintain a minimum signal
in the passband and of course, what kind of antenna they are using under
those conditions.  And this is best early on when there are only 1 or 2
usewrs at a time..

If you don't yet have PSK31, but want to get some data, team up with an HF
friend in your area and ask him to just transmit for the next 10 minutes
and you can then receie his downlink while commenting on his signal
strength throughout the pass.

>The prelaunch orbit estimate I saw was a 700 km x 350 km orbit with an
expected orbital lifespan of 3 years. I'm not sure how close that is
to the final orbit.
We don't know yet either, but perigee is nearer the morning passes and
apogee is nearer the later passes (THis is for the Northern Hemisphere.).
Both apogee and perigee being near the equator.

Bob, WB4aPR
On family travel and with very spotty Email till next week.


On Thu, May 28, 2015 at 2:58 PM, Red Willoughby <redski at bellsouth.net>
wrote:
> A couple of questions:
>
> How much power (to a dipole) is recommended for uplinking on 28.120 PSK31?
>
> Also, what is it's altitude?
>
> And, how long is its expected lifespan?
>
> Thanks in advance.
>
> Red
> KC4LE
>
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_______________________________________________
Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
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AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb