Subject: [IGSMAIL-2402] Additional EOW Rollover Consideration
From: Rebecca Casswell <[email-masked]>
Date: Thu, 5 Aug 1999 5:20:03 PDT

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IGS Electronic Mail      Thu Aug  5  5:20:03 PDT 1999      Message Number 2402
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Author: Rebecca Casswell <[email-masked]>
Subject: Additional EOW Rollover Consideration

NOTICE:
There is an additional consideration, regarding the 21/22 August GPS End of
Week Rollover.

Just after Thursday the 19th of August, 2200 Zulu, the almanac update to GPS
satellites will begin for week 0000.  The almanacs for week 0000 will be
updated in the entire GPS satellite constellation within 24 hours of the
first satellite being updated.

GPS receivers that are not 100% compliant with the ICD-GPS-200-C may
experience GPS receiver malfunctions when the almanacs are uploaded after
2200 Zulu, Thursday the 19th of August.  The actual End of Week Rollover is
in the "Subframe One" of the Navigation Signal and will happen 0000  (GPS
time) 21/22 August.  Users should contact their GPS receivers manufacturers
about ICD-GPS-200-C compliance.  For more detailed information reference the
ICD-GPS-200-C pages 121 - 133.

(Supplied by QMC J. Gispert, USCG liaison to AFSPC)

From: Rebecca Casswell <[email-masked]>

[Mailed From: Richard Langley <[email-masked]>]