[Sls-slp] CNES use of secondary header in frames

Greenberg, Edward edward.greenberg at jpl.nasa.gov
Mon Jun 1 16:07:23 UTC 2009

Gilles,  At the last meeting you stated that CNES places time in the
secondary header of TM frames.  I was wondering if you could elaborate on
the rationale.  Is it because you are using TM frames and the sequence count
is inadequate for playback of high rate data or what specifically is the
issue?  Would the use of AOS frames change the need or would you still need
a secondary header if you used AOS frames?

I have been examining the use of AOS frames for Constellation and have found
that the insert zone is useful for low rate AOS links but is a constraint
for higher rate links which could benefit from a signaled secondary header.
The use of a secondary header would also allow multiple Master Channels to
share a physical channel without the insert constraint.  I am interested in
proposing that the AOS frame specification should be amended to allow a
signaled secondary header.  This would facilitate the use of a security
header and the periodic insertion of a secondary header to carry voice codec
segments.  Secondary headers could easily replace the insert zone but
extracting the insert zone capability at this time is premature and
unnecessary since it is a managed field and it could easily be managed out
of use.

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