[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Use less uplink power!



Hi all,
I was qrv with my portable setup (25W into 2x8el X-yagi RHCP, 60cm dish)
on Orbit 1010 (Jan 11th, 1300UT). While receiving the beacon clearly and
strong, I was having real trouble hearing myself back.. I suspected a
fault in my TX system and cancelled the session only to learn that my
setup was perfectly working.. So I went into the telemetry from the
weekend: have a look yourself!

In the data file corresponding to Jan, 11th (A01010.tlm) if you display
(with P3T software) the  AGC for the U-Band RX, you will get a
interesting plot: AGC rises to up to 15dB at MA90 and staying over 10dB
up to MA200. But there is a sharp noth at apogee around MA128 and guess
what: it coincidences roughly with the transponder off time. 
But only roughly: There is a lag between the transponder and the high
AGC values of 1 to 2 telemetry blocks. The U-Band RX has been on all the
time, so this couldn't be radar interference.. this is the effect of few
users running too much (15dB!!) too high power.. or in other words: 

A station using 100W could run with 3 Watts instead !! I am not kidding,
read the reports from 1st transponder operations in May 2001..

You could argue that this is LEILAs job: keeping down the AGC level. I
don't blame the command team for this, because they have a hard job to
do, even without tweaking around with LEILA (thank you guys for
eveything!!). 

This is OUR job! Just make sure, that at least one station is stronger
than you..Life would be so much easier especially for us QRP stations.

73s Achim, DH2VA
----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home