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Re: UoSAT2 2.4Ghz antenna/beacon TX






As Dave wrote below i received from Alan GM1SXX a note regarding uo-11 power output:  Less than 100 miliwatt 
on a 3 turn helix and unconfirmed squint the attitude is controlled solely by the gravity boom gradient. Remain 
to be confirm power output on ao-40 S2 antenna to have a very good (week) signal reference source.



>>This beacon is a useful test
>>source for those testing mode-S converters, as an alternative to OSCAR-40.

The above statement is absolutely correct.  A weak signal like UO-11 is a much
better source to fine tune your receive setup.  I have to deliberately
attenuate AO40, the beacon is too strong to do any final adjustments.
40 is ok for the initial rough tuning. The short time 11 is available is a
bummer, and the doppler on 11 requires some doing, but it is doable.
When you eventually hear UO-11, it is very simple to change either AZ or
EL, and the result will positively determine whether or not it is 11.

The fact there is no modulation is also an advantage, the level is not changing
erratically.

UO-11 is certainly not for a beginner, but I use it all the time for a
final fine tune....Again, a pain to have to meet that short schedule,
but it produces good results.


> Luc,
> 
> Now that I'm back here at work I can confirm that UoSAT2 does indeed use a 3 
> turn helix on 2.4Ghz (I have photos of it here).
> 
> The UOSAT2 IERE technical article states that the beacon power is 100mw 
> (+20DBm) .... BUT, the beacon is known to have partially failed (so lower 
> power output than 100mw) ... AND the modulation level is much less than the 
> designers expected.
> 
> The spacecraft also has a 10Ghz beacon but to my knowledge it is never 
> switched on normally.
> 
> Both the 2.4 and 10Ghz helical antennas are positioned on a pair of sheet 
> metal 'wings' protrudung from the underside of the spacecraft structure.
> 
> Regards,
> 
> Allan Copland
> GM1SXX
> 
> 
> _________________________________________________________________
> Chat with friends online, try MSN Messenger: http://messenger.msn.com
> 


Luc Leblanc VE2DWE (AMSAT 33583)
Coordonnateur AMSAT pour le Québec
Quebec AMSAT coordinator
SITES WEB:http://www.sorel-tracy.qc.ca/~luclebla/
          http://www.qsl.net/ve2dwe/
C.P.341
Sorel-Tracy QC.
Canada
J3P 5N6


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