Hi Wouter
Bear in mind that this happened about a minute or two before LOS and took me by surprise so these are not scientific observations. I was monitoring the beacon both by ear and with a visual display on spectran. When the CW started the normal display gave way to the CW signal only and it appeared to be on the centre frequency of the DSB beacon signal. I assumed at first that this was simply a new mode for the beacon. There were a few CW characters and then the beacon resumed. The same thing happened about 15 seconds later and then a couple of times more before LOS. I then realised that this is the exact pattern of RS-30, 5 or six CW characters at 15 second intervals. When I brought RS-30 up on my display I discovered that RS-30 and Delfi have orbits that converge from opposite directions once on each orbit and this convergence just happened to occur over ZL on that pass. My next chance to have another look at this is the 2246 UT pass on 6 August but I would think this can be checked before that on rev 1484 over Europe at about 0930 UT on the 6th August.
Alan ZL2BX
-----Original Message----- From: Wouter Jan Ubbels [mailto:[email protected]] Sent: Tuesday, 5 August 2008 07:08 To: Alan Cresswell Cc: [email protected]; Delfi-C3 Mission Control Subject: Re: [Fwd: DO-64]
Hi Alan,
that is very strange. 435.315 is not a command frequency and is far away enough of the transponder uplink and the actual command frequencies so should not cause any trouble... How did you find out that the CW on 145.870 came from RS-30? Would be interested in your further observations!
thanks a lot and 73!
Wouter PE4WJ
On Tue, Aug 5, 2008 at 3:47 AM, Delfi-C3 Mission Control [email protected] wrote:
fyi
Hi Delfi team,
With no one other than myself to talk to on a 2226 UT DO-64 pass this morning I decided to monitor the beacon towards the end of the pass. Shortly before LOS the beacon stopped and sent CW for a second or two and then the beacon restarted. A few seconds later the same thing happened.
I
eventually realized that the CW was the RS-30 downlink signal at
435.315MHz.
The two spacecraft were on opposite tracks and approaching each other at this time. Why the 435.315MHz signal should stop the beacon and appear on the 145.870MHz beacon frequency is a mystery to me. I was about to post this on the amsat bulletin board when it occurred to
me
that there could be a slight possibility that the effect on the beacon
could
be because the RS-30 signal hit a command and control frequency at 435.320MHz so thought I would send it to you direct just in case. In the absence of any comment I will post the info on the Amsat bb for general interest. With the current orbits of Delfi and RS-30 they are in this relationship
on
a regular basis so I will see what happens next time to the linear
downlink
frequency.
Alan ZL2BX