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Re: JAWSAT/OPAL



    Jerry and all.  I missed hearing the packets as well.  I checked with John
    Mock and he was unsuccessful.  He suggested all of us find the EXACT start
    time of the packet so that we can count 255 seconds later for the next
    packet stream.  Cliff K7RR

More than just for the next burst, but for subsequence passes as well.
That is to say, if we have the time according to some welll known time
standard (there are several on the Internet), then N*255 seconds later,
another packet should be heard if its internal clock is accurate.  So if
anyone hears a please write down the exact time according to whatever time
piece you have handy.  Then later, you can compare your time piece against
NBS and post the exact time here on that basis.  (If you don't want to do
the math, then just post what your clock and what the time standard says,
and the time the burst was heard.)  

The rest of us can then use that to know approximately which portion of a
pass that JAWSAT reception should have priority for.  No 9600 decoder is
needed for the purpose, that time can be used by others to try for  actual
telemetry.

73's and good luck!
		       
		         -- KD6PAG  (Networking Old-Timer, Satellite QRPer)

-------------------------------------------------------------------------------
Date: Fri, 28 Jan 2000 16:50:07 -0800 (PST)
From: John Mock <kd6pag@qsl.net>
To: kc7qfs@amsat.org, n7sfi@amsat.org, kf4fdj@amsat.org
cc: kd6pag@amsat.org
Subject: JAWSAT suggestion

My partner gave me an idea that might help acquiring the 437.070 beacon.
Assuming the real-time clock on the OBC is reasonably accurate, if someone
can get the exact time (within a few seconds), then we might know when to
listen for the next pass (or even subsequent passes).  If T1 is the time
in seconds since launch (or whatever the UNIX standard time zero), and T2
is the current time (by the same measure), then we should hear the next
packet burst at roughly  255 - (T2-T1)%255 seconds (where '%' is the
modulus operator, for those unfamiliar with C code).  By knowing exactly
when to listen, then maybe someone who has 9600 FSK capability can grab
some real data from this bird.

		         -- KD6PAG  (Networking Old-Timer, Satellite QRPer)

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