[amsat-bb] more tests

[Francesco Messineo <iz5dwf@xxxxxxxxx>]

Hi all,
here're the results of new tests I've done trying to hear AO-40.
My station is in JN53EQ, now I'm quite sure I have good tracking software
as it gives AZ and EL figures which reasonably agree with those sent to
me by two other hams. On Aug 1, between 20.30 and 21.30 UTC I wasn't
able to copy the beacon around the frequency where it's supposed to be
(yes, plus or minus the doppler shift). I used the 34-turn helix and
parabolic's downconverter.
Then I started to point around the sky my antenna and tune around my
radio. First of all I noticed that the noise floor of the whole
system is S3-S4 from 144-146 MHz then it rapidly decrease to S1 outside
this range (tested from 143 to 149 MHz).
I found "strange" signals  around 147.500 MHz to 148.500 MHz, which
should be around 2403.500 to 2404.500 according to my converter specifications.
The signals appear to coming from AZ= 240 to 270 (approx) and EL=30 to 40 
and have been observed for 15-20 minutes around 21.30 UTC (then I went
QRT). What I heard is signals that sound like SSTV on 2407.968 with S3 to S4
strength (S1 is the nois floor here), similar signal, around S2, on 2408.055
also I found a strong (S9) carrier (seems not modulated) around 2408.011.
For the short period of my observation I couldn't hear any doppler shift.

Now the question is: I'm hearing something that is well known? Or it's
a product of an image frequency? Can I assume that the LO frequency of
my dowconverter is reasonably precise (given that they say it should
convert 2400 MHz frequency to 144 MHz)? How can I test that the LO freq
is what it should be?
Has anyone a sample wav file of the AO-40 beacon, just to hear how it should
sound like?


Thanks and best regards.


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Francesco Messineo 	iz5dwf@amsat.org
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