[Secretariat] Re: [Cesg-all] V2 GSCIDs usage

[Thomas Gannett]

John:

The simple answer to your question is that the statement is 
true.  Whether it is really necessary is another matter.  V2 SCIDS 
can be used only in V2 (AOS) frames, and normal telecommand uses a V1 
frame.  There may be some implementation of bidirectional V2 frames, 
but in almost all cases when AOS is used for telemetry, conventional 
telecommand is used on the forward link.

For spacecraft with V1-forward/V2-return links, the operator often 
requests the same values for V1 and V2 SCIDs, but the overlap of free 
SCIDs in the two lists grows smaller with each assignment.

Tom


At 04:57 AM 7/3/2009, Gian.Paolo.Calzolari at esa.int wrote:


>cesg-all-bounces at mailman.ccsds.org wrote on 02-07-2009 19:26:34:
>
> > Hi,
> >
> > When registering V2 CCSDS Spacecraft IDs, we have routinely been sending
> > out a confirmation that includes this
> > statement:
> >
> > As a reminder, Version 2 SCIDs are only useful for telecommand when
> > using AOS-VCDU.
> >
> > I just wanted to check that this still remains accurate.
>
>John,
>         just a silly doubt/clarification.
>
>v2 SCIDs are 8 bits long while v1 SCIDs are 10 bits long (as per 
>CCSDS 320.0-B-5 and other books).
>Therefore v2 SCIDs are a subset of v1 SCIDs (numerically speaking).
>In principle one could use a 8 bits v1 SCID on a spacecraft and the 
>same (value) 8 bits  v2 SCID since they would generate different 
>GSCIDs (being GSCID = VN . SCID i.e. concatenation). The same can be 
>extended to v3 SCID values of course.
>
>If you assign a value as v2 SCID, what do you do with the same value 
>as v1 SCID?
>Do you freeze it or is it available for somebody else (even 
>belonging to another space agency)?
>I assume that a space agency can request to have allocated the same 
>value as v1 and v2 SCID. Correct?
>
>Thanks
>
>Gian Paolo
>
>
>
>____________________________________________
>
>Gian Paolo Calzolari
>Systems Engineer, OPS-OT
>
>European Space Agency ESA/ESOC
>Robert Bosch Str. 5
>D-64293-Darmstadt
>Tel +49-6151-902913 fax +49-6151-902962
>http://www.esa.int/esoc    Email: Gian.Paolo.Calzolari[at]esa.int
>[replace [at] with @ for the correct e-mail address]
>____________________________________________
>
>

Thomas Gannett
+1 443 472 0805 
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