[amsat-bb] AO-7 report.

John Hackett archie.hackett at hotmail.com
Wed Oct 17 00:24:28 PDT 2007

Regular users will have noted that the AO-7 mode-B transponder has begun to "behave" again.

We're still not sure 'exactly' what happened, several "theories" have been bandied about ... what is certain !!! is that it was a power related problem so let us concentrate on *NOT* belting her with excessive power.

When you can't hear yourself adequately ... IMPROVE YOUR RECEIVE CAPABILITIES.

Cranking up your transmit power to compensate for an inadequate receiving system is *NOT* the way to go. Remember ... AO-7 is running at less than optimum in all 4 modes. Let's not accelerate her second demise by screwing up the power budget anymore than it already is.

Excessive power *WILL* shorten the satellite's life. If, through lack of experience you don't understand why ... please take the trouble to find out. 

I read on the Internet yesterday one prominent satellite operator, a PA station, list part of his equipment as 100w and 2 x 10 element beams. He specify whether this was 100w EIRP or 100w fed to the aerials ... I most certainly hope it was *NOT* the latter since assuming a line loss of 3dB that would give an EIRP of well over 500 watts with today's compact 10 element beams ... enough to melt the plastic holding AO-7's solar panels on the spaceframe.

(Yes, I'm kidding ... but 500w EIRP is 450 too many for AO-7).

Please remember, 31 years ago not all the "bits n' pieces" were space-rated.

Three things you should improve for better AO-7 operating. 

1) Receive capability.
2) Receive capability.
3) Receive capability.

At 06:27 UTC this morning I noticed something I havn't heard for two years ... that which I presume was echos of the BMEWS radar, I was rather "bemused" (pun intentional). It sounded like a rapid machine-gun like auroral woodpecker ... or if you've never experienced aurora propagation, like blowing through your nose into the neck of a glass bottle ... "keying" it at about 65 wpm.

GM1SXX and myself suspected the Fyllingsdale BMEWS radar situated on the north Yorkshire moors in the UK ... 

BMEWS = ballistic missile early warning system.

For a detailed description see ... 


73 John.   <la2qaa at amsat.org>

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