[amsat-bb] Re: [Prospero Commanded Pass Today]

[g.shirville at btinternet.com]

Hi Jan,

FWIW - my reading of the slightly old fashioned English text, is that the 
command transmitter is on a frequency around 148MHz, that it uses "two 
tones" and that the on board receiver and decoder is capable of 
understanding 35 commands. As it happens, the ground segment for the Orbcomm 
constellation also uses similar frequencies and "tones", so maybe you 
actually heard a ground based device nearby to you, doing its uplinking?

73

Graham
G3VZV

-----Original Message----- 
From: PE0SAT
Sent: Tuesday, October 25, 2011 3:31 PM
To: rjad at mssl.ucl.ac.uk
Cc: amsat-bb at amsat.org
Subject: [amsat-bb] Re: [Prospero Commanded Pass Today]



Hi Roger,

The information about a second freq. came from the following document:

http://www.pe0sat.vgnet.nl/downloads/Prospero-Satellite.pdf written by
H.J.H. Sketch.

Have a look at part 3.1

Here a part of that paragraph

"The v.h.f. system is conventional using twin transmitters, each with an
output of 350mW at approximately 136 MHz, and a twin tone digital command
system operating at about 148 MHz which handles the 35 separate commands"

Second graph I placed last night looks like a twin tone, and is received
around 148.010 MHz.


With regards,

Jan - PE0SAT


On Tue, October 25, 2011 15:43, Roger Duthie wrote:
> I don't think there is a 148MHz transmitter, though Prospero's uplink is
> 148.25MHz.
>
> Also, after looking at your page I think I should say that we think that
> the Coast BBC transmission was almost certainly  an Orbcomm
> transmission.  The Prospero downlink frequency was reassigned to Orbcomm.
>
> Which sound file are you talking about?  There are what claims to be
> original audio files here: http://www.dd1us.de/spacesounds%204.html (you
> need to find Prospero further down the page).
>
> - Roger
>
> PE0SAT wrote:
>> Hi Roger,
>>
>> I have updated
>> http://www.pe0sat.vgnet.nl/satellite/sat-history/prospero/
>> with my latest images and recordings. It is possible to get the complete
>> audio file. Send me a direct email and we can arrange something.
>>
>> I had read that there is a 148.000 MHz transmitter on board prospero,
>> and
>> I listend to that frquentie during the pass from 15:55 UTC. Maybe it is
>> interesting what is happening on that transmitter.
>>
>> How do things go on your site regarding PROSPERO? any news?
>>
>> 73 Jan PE0SAT
>>
>> On Mon, October 24, 2011 13:01, Roger Duthie wrote:
>>
>>> AMSAT community -
>>>
>>> The Mullard team intend to attempt commanding to Prospero during the
>>>
>> following pass:
>>
>>> (entries are: date; mag; start time; el; az; max el time; max el; az;
>>>
>> end time; end el; end az)
>>
>>> 24 Oct
>>> <http://www.heavens-above.com/Gtrack.aspx?Session=kebgfdalljnnahdmapeidbkh&satid=5580&date=40840.6673023843>
>>> 7.7 16:54:17 10 SSW 17:00:54 58 WNW 17:08:40 10 N
>>>
>>>
>>> Any listening on the downlink, and feedback on your observations, would
>>>
>> be most appreciated.
>>
>>> We may also try the later pass:
>>>
>>> 24 Oct
>>> <http://www.heavens-above.com/Gtrack.aspx?Session=kebgfdalljnnahdmapeidbkh&satid=5580&date=40840.7412698495>
>>> 9.3 18:42:56 10 W 18:47:25 17 NW 18:52:14 10 N
>>>
>>>
>>>
>>> **** TIMES ARE IN BST (ie., UTC + 1) ****
>>>
>>> - Roger
>>>
>>> PS., I hope the copy-paste from heavens-above works.
>>>
>>>
>>> _______________________________________________
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>>> author.
>>>
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>>
>>
>
>
>


-- 
With regards PE0SAT
Internet web-page http://www.ham.vgnet.nl/


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