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Re: UO-11 and NO-44 over ZL



On Mon, 9 Sep 2002, Alan W Leech wrote:

> NO-44 has not been heard for several days, now. Has it succumbed to the
> ravages of solar emmissions?

NO-44 or PCsat is working fine *in the sun*.  When it comes out of
eclipse, it takes about 10 minutes before it is strong enough to support
digipeating.  RIght now in the northern hemisphere, it's passes are
occuring at night and early morning, so only the last 2 of the 7 passes a
day are usable...   THe first pass is happening after 11 PM when the
satellite has been in the dark for over 10 minutes and the batteries are
just about out of power again.

But since these passes move earlier by 30 minutes a day, in less than a
week, PCsat will be usable again in the early evening and earlier and
earlier over the next moonth.  PCsat will enter full sun again in Late
September and be fully usable around the clock..

It has taken me a while to realize a very simple aspect of Satellites
(ones that have poor power systems and can only operate in sun), and that
is that we rotate through a 24 hour day, and LEO satellites orbit in a 100
minute day, so for every HOUR of "your time" equals about 4 minutes of
satellite time.

Thus, when you see a pass 3 hours after YOUR sunrise, this means the
satellite (on this pass) has been in the sun 3*4 or 12 minutes.  For
PCsat, this is enough to charge its batteries to have enough PEAK current
to handle a 2 watt packet burst.

Similarly, 3 hours after sunset, PCsat has been running for about 12
minutes on battery power alone, etc...

Bob


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