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AO-40: LEILA is On!



Dear All,

history was made on Sunday (May 12th) when the LEILA system
on AO-40 was turned on for the first time!

This morning a couple of *very* strong signals appeared in the
passband, several dB louder than the MB!!!

Several people tried to get them to reduce power, but they apparently 
weren't listening.  The AGC on the U-band Rx was suppressing up to 16 dB,
clearly in sync with their transmissions and there was massive grumbling 
on the passband.... 

Remember that the MB is 8dB louder than the GB and users should not
be stronger than the GB..

So, it was decided that this might be a good chance to test LEILA.
LEILA was switched into the U-band passband, which can be seen
by the MATRIX configuration.  LEILA was configured for SCAN/JAM/NOTCH
mode and it worked like a charm!!  

The threshold was set to a level which was approximately equal to 
the GB signal, which means any stronger signal will be detected by
LEILA..  an "police siren" will be heard to give a chance to reduce
power, otherwise the notch will do it's best... :)
People on the passband loved it!

This is indeed another major success within a few weeks for AO-40
and in particular for the LEILA concept (LEIstungs Limit Anzeige),
which was designed by AMSAT-DL (Dr. Karl Meinzer DJ4ZC and Matjaz Vidmar
S53MV) and also supported by the german ministry of science and technology.
Indeed, it is the first time that such a system is used in space for
a transponder with uncoordinated multiple access.

If everything goes well, we will probably leave LEILA continuously
in the loop..

Meanwhile the RUDAK team did also good progress and both CPU's are
running now for more than 10 days.

In a 6 hour effort on friday morning Jim White WD0E finished loading 
the GPS task into RUDAK-A and loaded the CEDEX task.  Both tasks are 
running but commands to begin their operations were not yet sent. 
This is planned for saturday or sunday, when data from CEDEX will
be logged and possibly a GPS lock sequence will be initiated.
Jim also reported that RUDAK-A TLM continues to look normal and also
the SmartNode temperature sensors on the CAN bus seem to work fine.
Both 153.6 KBit/s highspeed PSK downlinks were also verified 
and they came on as expected and were turned off again later.
While at zero Doppler the downlink frequencies of the 9k6 hardware 
modulators through S1 are:
RUD A mod 0 = 2400.791
RUD A mod 1 = 2400.765
RUD B mod 0 = 2400.910
RUD B mod 1 = 2400.891
(measured with an accuracy of +-5 KHz)

And finally...  X-band and possibly C-band testing this morning!!!


73s Peter DB2OS for the whole AO-40 team

---
Peter Guelzow, DB2OS
President AMSAT-DL
http://www.amsat-dl.org

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