[amsat-bb] Re: [Re: Prospero] Commanding Error

Tony Abbey afa3 at leicester.ac.uk
Thu Oct 27 09:02:37 PDT 2011 

Hi Roger

Once Graham told me the noise was Orbcomm this morning, I added the TLEs for their satellites (http://www.orbcomm.com/Collateral/Documents/English-US/o11292.tle)
 to my SDR Radio software satellite definitions. Here's a pass I recorded from one of them this morning, and you can see that the "chuff-chuff" on the left hand side has structure which is kept vertical by the doppler correction. The other crap and pager cross talk etc bends with the doppler correction. I think that proves the point.

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 27 Oct 2011, at 16:17, Roger Duthie wrote:

> We're hearing these 'chuff-chuff swooshes' too, though at times when our software is not showing Orbcomm over our horizon.  Our TLEs may be slightly out-of-date, though I think it would be a marginal thing.  Can it be definitely confirmed that these noises are Orbcomm?
> 
> - Rr.
> 
> Tony Abbey wrote:
>> 
>> Nothing heard from Prospero here in Leicester, that pass just finished (at 14:57Z)
>> Just the Orbcomm swooshes.
>> 
>> 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 27 Oct 2011, at 13:33, Roger Duthie wrote:
>> 
>>> Well, we're hearing something like that.  Though we hear this a lot, we also wonder whether we''re seeing an envelope during the Prospero pass times.  
>>> 
>>> The passes for today (BST) [from Heavens-Above]:
>>> 27 Oct	7.2	15:42:26	10	S	15:49:21	77	E	15:57:21	10	NNE
>>> 27 Oct	8.7	17:28:31	10	WSW	17:34:45	31	WNW	17:41:39	10	N
>>> Also, I've started a Twitter hashtag for anyone using this mode of communication: #Prospero40  Add this to any Twitter messages you might write about Prospero or related subjects.
>>> 
>>> -Roger
>>> 
>>> PE0SAT wrote:
>>>> 
>>>> Hi,
>>>> 
>>>> I have a spectrogram and a recording of that "chuff chuff" on
>>>> http://www.pe0sat.vgnet.nl/satellite/sat-history/prospero/
>>>> 
>>>> Is it the same you guys heard?
>>>> 
>>>> 73 Jan PE0SAT
>>>> 
>>>> 
>>>> On Thu, October 27, 2011 10:04, g.shirville at btinternet.com wrote:
>>>>   
>>>>> 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 at mssl.ucl.ac.uk
>>>>> Cc: Phil Guttridge ; amsat-bb at 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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>>>>> _______________________________________________
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>>>>> 
>>>>>     
>>>> 
>>>> 
>>>>   
>>> 
>>> -- 
>>> ---
>>> Roger J A Duthie
>>> PhD Candidate
>>> Plasma Group
>>> Department of Space & Climate Physics
>>> UCL, London
>>> 
>>> w: +44(0)1483 204 100 ext 2299
>>> m: +44(0)7938 55 70 44
>>>     
>> 
> 
> -- 
> ---
> Roger J A Duthie
> PhD Candidate
> Plasma Group
> Department of Space & Climate Physics
> UCL, London
> 
> w: +44(0)1483 204 100 ext 2299
> m: +44(0)7938 55 70 44

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