GPS rollover day

From: satcom ops via Seesat-l <seesat-l_at_satobs.org>
Date: Sat, 6 Apr 2019 07:03:13 +0100
Hi

I posted about this a few weeks back , but today is the day!

If using and older design of GPS receiver for time stamp work etc it 
will be worth checking the accuracy today following the 1023 roll over 
period.


NAVAREA I  033.
POTENTIAL PROBLEMS FOR USERS OF GPS RECEIVERS.
1. USERS OF GPS RECEIVERS ARE ADVISED OF POTENTIAL
    PROBLEMS DUE TO GPS WEEK COUNTER ROLL OVER ON
    06 APR 19.
2. THE GPS SYSTEM TRANSMITS TIME TO GPS RECEIVERS
    USING A FORMAT OF TIME AND WEEKS AFTER THE START
    DATE OF 06 JAN 80. THE DATA FIELD IN THE NAVIGATIONAL
    MESSAGE SENT BY GPS SATELLITES CONTAINING THE NUMBER
    OF WEEKS AFTER THE START DATE IS LIMITED TO A MAXIMUM
    OF 1023 WEEKS.  WHEN THE GPS SYSTEM REACHES WEEK 1024,
    THE SYSTEM WILL REVERT BACK TO WEEK ZERO.
3. SOME GPS RECEIVERS ARE KNOWN TO BE UNABLE TO MAKE
    THE TRANSITION FROM WEEK 1023 TO 1024. IF THE GPS
    RECEIVER IS OUTDATED OR LACKS PROPER UPDATES,
    THE RECEIVER WILL REVERT TO READING THE WEEK ZERO
    AS AUGUST 1999. DURING THIS TIME THE INTERNAL CLOCKS OF
    THESE GPS RECEIVERS WILL EXPERIENCE A LACK OF ABSOLUTE
    REFERENCE AND MAY GIVE THE WRONG TIME AND POSITION OR
    MAY LOCK UP PERMANENTLY.
4. SOME OF THESE GPS RECEIVERS ARE REPAIRABLE WITH
    UPGRADES AND OTHERS WILL BECOME UNUSABLE. USERS ARE
    ADVISED TO CHECK WITH THEIR GPS MANUFACTURER REGARDING
    THE STATUS OF THEIR RECEIVER.
5. FOR FURTHER INFORMATION SEE:
    A. GPS WEEK ROLL OVER ISSUE
       www.gps.gov/cgsic/meetings/2017/powers.pdf.
    B. TIMING CRITICALITY & GPS 1024 WEEK ROLLOVER
       www.gps.gov/governance/advisory/meetings
       SELECT NOVEMBER 2017 AND THEN TIMING CRITICALITY &
       NOTE ON "GPS WEEK-ROLL-OVER"
    C. GLOBAL POSITIONING SYSTEMS DIRECTORATE,
       SYSTEMS ENGINEERING & INTEGRATION INTERFACE
       SPECIFICATION IS-GPS-200,
       www.gps.gov/technical/icwg/IS-GPS-200J.pdf.
6. FAILURE TO VERIFY YOUR GPS RECEIVER COULD LEAD
    TO SERIOUS NAVIGATIONAL PROBLEMS PLACING LIVES
    AND PROPERTY AT RISK.
7. CANCEL THIS MESSAGE 132359 UTC APR 19.

Regards

John




---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

_______________________________________________
Seesat-l mailing list
http://mailman.satobs.org/mailman/listinfo/seesat-l
Received on Sat Apr 06 2019 - 01:04:00 UTC

This archive was generated by hypermail 2.3.0 : Sat Apr 06 2019 - 06:04:00 UTC