[amsat-bb] Re: Notes on 2.4 GHz beacon

[Yoshihiro Imaishi <imaishi@xxxxxxxxxxxx>]

Hello all. this is Yoshi.

At 2000/11/30 03:53:23 Stacey E. Mills, M.D. wrote:
> The 400 bps GB (telemetry just like the V-Tx MB) has been set up on the S1 
> transmitter (nominal freq. = 2400.2 MHz) from MA = 20 to 26.

  This morning, I tried to hear it, but the signal is not modulated,
sound like just pure carrier. I could not hear the 145.898 MB at
same time because I have only one rig that can receive 2m SSB, and
I put it just opposite side of my operating disk to look at south-
east sky HiHi.

  My next chance is tomorrow, so please somebody who will try
to hear it at EU,SA or East coast NA after 09:00z tonight, to
watch both 2m and 2400MHz beacon at same time, and if possible,
please check that status on telem. during MA 20-26.

  I hope that the signals I heard is really came from Sat. :-)

> Keep a few things in mind.  First, the S1 antenna is highly 
> directional.  At squint angles greater than 35-40 degs, I don't know how 
> loud/weak the signal will be.  Also, at these relatively high offpointing 
> angles the normally right-hand circular polarization, may be predominantly 
> left-hand, which will also decrease the signal if you've got a right-handed 
> antenna.  

  Due to the condition of ALAT -9, and 6 degree inclination of
GTO, the beam antenna might be pointnig little bit out to south
from the earth  - maybe 10 or 15 degrees? at here PM53.
  I heard the carrier signal as weak at Signal Strength 1 with
my home brew 10 ele YAGI beam and modified Drake downconverter.
I do not know that it was due to my poor antenna or attitude of
sat. But I could hear.

> Finally, as has been mentioned, doppler at this frequency and 
> this point in the orbit is going to be dramatic.  As a "guestimate", 20+ 
> KHz down is not unreasonable if the satellite is moving rapidly away from 
> you.  If you have doppler correction software, the current NORAD keps are 
> very good and should get you close to the frequency, but scan around.

  I thought that the doppler shift will move faster more than FO-29s
one at 435MHz, but it was moving up more slowly that FO-29. I
think that MA 20 or more is far enough from earth, and the vector
speed will not change so quickly likes as around MA 0.

have a good fun!.  73 de Yoshi JF6BCC/KH2GR

Yoshihiro Imaishi JF6BCC/KH2GR
mailto:imaishi@aa.mbn.or.jp  
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