[amsat-bb] rs-15 beacon informative?

auke sparkycivic at shaw.ca
Sat Oct 27 12:09:27 PDT 2007

I have been listening to the RS-15 beacon lately since reading about it having been heard back on the air intermittently.
It seems that the beacon might have something to tell us!  I noticed today that the rate of keying of the transmitter seems to be affected either by environmental factors, or on purpose, as in having been designed to do this...

What I observed is this: 
All observations were made while tuned to 29.3520 MHz and then down to about 29.3512 to compensate for doppler by the end of the pass...
The beacon transmitter was keying on/off about 2 seconds/2 seconds with it's characteristic initial "chirp".  This is what I saw during my first time observing it, last week.  The difference is that today, the beacon key-down length began to get longer, while it's off-time was the same!  There were several 15-plus second transmissions in a row at the longest, then the duration rapidly shortened again subsequently, returning to the 2/2 timing after only a few transmissions. 
I have some visual and audible recordings of this pass available on my personal shaw account, for the criticism of anyone so interested.  
screenshots of the spectran audio spectrum during different parts of the pass:
and the audio recording as MP3:

Could this be an indication of some onboard parameter like internal temperature, or perhaps solar panel voltage?  The spacecraft orbit is currently in a non-eclipse season.  This might be a good oportunity to learn about the condition of the onboard systems, and even try-out the transponder.  I would try it, but I dont' have much uplink power or antenna persuasion to conduct a conclusive 

Auke de Jong,
Edmonton, AB,

10 meters: HTX-100, wilson mag-mnt whip at 2 meterselev
2 meters: Yaesu FT-726R, omni VP, onmi HP 70W classC, 10W ssb
70cm: Yaesu FT-726R, 7el yagi az rot, Omni HP 100W linear

More information about the AMSAT-BB mailing list