[amsat-bb] RE: AO-40 telemetry

[paul.willmott@xxxxxxx]

Charlie,

What you will observe on a pass starting at MA 0, will be very fast Doppler
that makes capture of good blocks impossible, ... by MA 2 the Doppler will
have slowed so that good capture of blocks should be possible, ... this will
continue until around MA5, then the spin of the S/C will break up the
signal, as the antenna hides behind the engine bell on each spin (17rpm),
... then the signal will come good again at say MA7, and maybe good until
MA8 or 9. then spin problems will re-occur. The first good blocks are from
the main node of the antenna, and the second good blocks from a side lobe of
the antenna. If your pass starts at say MA 6, just add 6 to the above
observations, you'll probably get good data to MA16 or 18 if you are lucky.
After MA18 the breakup of the signal by spin means that good blocks are
almost impossible even with a big dish, ... its not a signal strength issue,
its just that the signal is not there due to the engine bell/ S/C frame.

You can also try MA 249 to 253, ... the other side lobe of the antenna
points good in this portion, we havn't had many good blocks from here, but
it is possible.

Paul

-----Original Message-----
From: Charles Suckling [mailto:csuckling@nhlab.demon.co.uk]
Sent: Thursday, March 01, 2001 9:59 AM
To: paul.willmott@omsl.bm
Subject: RE: AO-40 telemetry


Paul

Thanks for info.  Probably too much fading this morning then.

Hope to try on next orbit - if I can stay awake!

Glad the archive was OK.

73

Charlie

At 07:16 01/03/01 -0400, you wrote:
>Hi Charlie,
>
>You'd be very unlikely to get CRCC OK data at MA15 these days, ... at the
>moment we are only getting CRCC OK data from MA 2 to MA12ish. Yes AO-40 was
>commanded into D Block dump mode at around MA 9 today, ... the command
>stations are downloading some jpegs from the CCD camera. They will be doing
>the same on the next pass, ... which is a much better one for the UK!
>
>Cheers
>Paul
>
>p.s. your zip worked fine! 
>
>-----Original Message-----
>From: Charles Suckling
>To: paul.willmott@omsl.bm
>Sent: 3/1/01 5:42 AM
>Subject: AO-40 telemetry
>
>Paul
>
>I am sending some data to the archive frmo 19 Feb, to test it is OK.
>Never
>zipped anything before, so hope its OK.
>
>Listened this morning from 0730 (MA 15).  Signal was good, and every
>block
>synched up OK, but every block was bad.  Frustrating!  Wondering if it
>is
>my system!  Looks like all blocks were data as there was nothing in the
>ao40rcv windows apart from the raw data window. Each line seemed to
>start
>with C4 20 50 45 26 or something like that.
>
>73
>
>Charlie
>
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