Subject: [pilc] OT - CCSDS Proximity-1 Help Req'd

From: "Long, Darren" <[email-masked]>
Date: Fri, 19 Dec 2003 11:43:52 -0000

Hi,

Sorry for being a bit off topic, but wondered if anyone can provide a bit of
guidance w.r.t. the CCSDS Proximity-1 Link Protocol.  I can't think of
anywhere else to ask.

The specification for the Proximity-1 Physical Layer (211.1-B.1) on Page
3.9, section 3.5.1 "Delivered Bit/Symbol Stream Error Rate mentions links
where Reed Solomon coding in the data-link layer.  So far (and I admit that
I haven't read every word of the Proximity-1 documents) I can't find any
reference to use of an RS code in any of the three newly restructured
documents.

I am interested in using an off-the-shelf protocol for a narrow band
half-duplex ground-to-air UHF data-link and have been wondering about
adopting elements of Proximity-1.  Currently I'm in favour of a concatenated
RCPC,RS combination, similar to that described by TM Sync & Coding, for both
uplink and downlink ), but Proximity-1 only seems to support the
convolutional codes.

Obviously I don't need to be compliant with the standard, and can tailor as
needed, I'm just curious about the reference to the RS code and wonder if it
could be an error.

If responding direct, and not via the list, please send to both of my email
addresses.

[email-masked]
[email-masked]

Thanks for any help you can give...

Darren Long

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---

From: "Adrian J. Hooke" <[email-masked]>
Date: Fri, 19 Dec 2003 07:36:00 -0800

Darren: Greg Kazz, chairman of the CCSDS Space Link Protocols Working 
Group, will be happy to answer your questions. I've CC'd him and he will 
answer you directly.

I have also copied Matt Cosby of QinetiQ and Dai Stanton of Keltik (both in 
the UK), who implemented Prox-1 onboard the British 'Beagle' lander that is 
scheduled to touch down on the surface of Mars on Christmas day. They 
should be able to give you local advice.

Prox-1 will be the primary communications link for Beagle to transfer data 
to and from Earth via the European 'Mars Express' orbiting communications 
relay, and the US 'Mars Odyssey' orbiting relay. The two US Mars rovers 
'Spirit' and 'Opportunity' (respectively scheduled to land on Mars January 
3 and January 24, PST) will also each use Prox-1 for communicating via 
these two orbiting Mars relays. The US 'Mars Reconnaissance Orbiter' 
(http://mars.jpl.nasa.gov/mro/mission/tl_relay.html) will join the 
international fleet of Prox-1 based Mars communications relays when it 
arrives at the planet in March 2006.

All of these proximity communications occur in the UHF band.

Best regards

Adrian J. Hooke
Chairman, CCSDS Engineering Steering Group (CESG)
NASA Jet Propulsion Laboratory,
Interplanetary Network Directorate
Pasadena, California 91109-8099, USA
+1.818.354.3063
http://www.ccsds.org

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
At 03:43 AM 12/19/2003, Long, Darren wrote:
>Hi,
>
>Sorry for being a bit off topic, but wondered if anyone can provide a bit 
>of guidance w.r.t. the CCSDS Proximity-1 Link Protocol.  I can't think of 
>anywhere else to ask.
>
>where Reed Solomon coding in the data-link layer.  So far (and I admit 
>that I haven't read every word of the Proximity-1 documents) I can't find 
>any reference to use of an RS code in any of the three newly restructured
>documents.
>
>adopting elements of Proximity-1.  Currently I'm in favour of a 
>concatenated RCPC,RS combination, similar to that described by TM Sync & 
>Coding, for both uplink and downlink ), but Proximity-1 only seems to 
>support the convolutional codes.
>
>Obviously I don't need to be compliant with the standard, and can tailor 
>as needed, I'm just curious about the reference to the RS code and wonder 
>if it could be an error.
>
>If responding direct, and not via the list, please send to both of my 
>email addresses.
>

---

From: "Adrian J. Hooke" <[email-masked]>
Date: Fri, 19 Dec 2003 07:36:00 -0800

Best regards

Adrian J. Hooke