Hi Tony,
The chuff chuff noises are from space...they are a sort of beacon carried on every Orbcomm satellite. They are 125msec long pulses of 57.6kb data and have a bandwidth of around 50kHz. They are quite distinctive when you only hear one at a time but sometimes one can hear two or more signals at the same time and that sort of changes the sound:)
73
Graham G3VZV
-----Original Message----- From: Tony Abbey Sent: Wednesday, October 26, 2011 8:56 PM To: rjad@mssl.ucl.ac.uk Cc: Phil Guttridge ; amsat-bb@amsat.org Subject: [amsat-bb] Re: [Re: Prospero] Commanding Error
Hi Roger
Nothing other than the chuff- chuff on the 1600 pass. And as you said, its also there with Prospero over the horizon. I 'm not using a beam presently - using a 360deg parasitic Lindenblad for circular polarisation, but it is susceptible to all the high power pager stuff nearby. Its just strange that there are elements shifting in frequency in the chuff chuff like a signal from a real satellite. Have just come back from a Rosat re-entry celebration!
Tony Abbey - Senior Research Fellow (retired) Space Research Centre Dept of Physics and Astronomy University of Leicester University Road SRC Web page: http://www.src.le.ac.uk LEICESTER LE1 7RH, United Kingdom
On 26 Oct 2011, at 16:17, Roger Duthie wrote:
Tony -
We heard something intriguing after about 14:43:40 UT as the tracking said the satellite was on it's way off to the north pole.
The 'chuff-chuff' description reminds me of a sound we seem to hear quite a lot. Quite often it coincides with a pass, though I think we hear the same (or very similar) during times when Prospero is over the horizon.
We are going to try the next pass at ~16:00UT if you want to listen in again. Our new ploy is to wait for the last most opportune moment to command, as the power _may_ be at it highest (longest charging of batteries, potentially). So, we'll do short commanding at above 30o el, and listen.
-Rr.
Tony Abbey wrote:
Hi Roger
I could hear some "chuff-chuff" noises on the last pass and they show a related doppler shift (although I am not correcting sufficiently) as you can see in the attached plot. Maybe its some other noise but you never know.
On 26 Oct 2011, at 13:39, Roger Duthie wrote:
Commanding went well, from as far as we could make out. We're not sure if we're getting anything back, however.
We'll be doing this pass today, hopefully:
26 Oct 7.3 15:31:43 10 S 15:38:26 60 E 15:46:11 10 NNE [Times in BST = UTC + 1]
-Roger
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