[Sls-rfm] [Sls-slp] Table form of Prox-1 Phy Layer

[Greg Kazz]

Matt,

Tom Gannett generated the pink sheets in CCSDS format and I sent them out. 
They contain the symbol to symbol addition you and Lester recommended at 
the Fall meeting. It includes the paragraph on the symbol to symbol deviation.

After that Dennis Lee discovered that we could more precisely capture part 
of these requirements in a table. I sent that proposal out as well. I said 
that it was only a format change. I forgot to include the symbol to symbol 
deviation paragraph into Dennis's proposal. However, they are included in 
the official pink sheets.

Greg
>Greg,
>
>here are the BNSC responses to the new pink sheets...
>
>See you in Athens.
>
>Matt.
>
>We would like to voice our concerns regarding this new pink sheets for the 
>data rate stability for Proximity-1. These concerns have been developed in 
>consultation with engineers at QinetiQ (Steve Kynaston, Dai Stanton and 
>myself) who have been responsible for several baseband and RF CCSDS 
>systems, including 2 implementations of Proximity 1.
>
>We can't accept a change to a recommendation just because a single 
>implementation cannot meet the current specification. The reason why 
>Electra could not meet this requirement is due to a design decision not 
>because the specification is too stringent. Making this type of change has 
>serious knock-on interoperability issues.
>
>The correct cause of action would be for the Electra implementers to issue 
>a waiver, to their customers, indicating that they don't meet the current 
>Proximity-1 specification. We should not accommodate in the recommendation 
>a symbol-to-symbol timing deviation that could lead to, at best, large 
>implementation losses in the bit synchroniser and, at worst, a total 
>inability of a bit synchroniser to track the incoming data.
>
>We believe that the modifications made to the recommendation at the Autumn 
>2004 meeting have severely compromised interoperability between orbiters 
>and landers (both extant and planned) by not specifying a symbol-to-symbol 
>frequency deviation. The current form of words and, to a greater extent, 
>the statements in the pink sheets allow for pathologically behaved 
>baseband implementations which would be impossible to decode. (E.g. a 
>waveform which had a symbol 99 bit periods long followed by 99 symbols 
>squeezed into a single period). We do not believe that it is prudent to 
>issue a recommendation which does not provide enough rigor to guarantee 
>orbiter/lander interoperability at the bit synchronisation level.
>
>
>
>------------------------------------------------
>Matthew Cosby
>Digital & Embedded Technology,
>Space Department,
>Arthur C Clarke Building,
>QinetiQ Ltd,
>Cody Technology Park,
>Farnborough,
>Hants, UK.
>GU14 0LX.
>
>Tel:            +44 (0)1252 396313
>Pager:  +44 (0)7659 130547
>------------------------------------------------
>e-mail  : MCosby at space.QinetiQ.com
>WWW : http://www.QinetiQ.com
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