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Description of GPS Week Count Flip

by bynav


Recently, the US Civil GPS Service Interface Committee (CGSIC) issued a GPS week count on the US Department of Homeland Security website to alert us of the second rollover event at 0:00 on April 6, 2019 UTC time.

The reason for the GPS week count flip is that in the GPS navigation message, the weekly count occupies a 10-bit field, and the weekly count will cycle in the 0-1023 interval. When the GPS weekly count actually reaches 1024, the weekly count in the navigation message will flip to zero and restart counting. The current GPS cycle began on August 1, 1999, and the number of Japanese cycle weeks returned to zero on April 6, 2019.


Our receivers, in some versions, have improved areas of flipping exception handling when working with a single GPS. Now upgrade the program and perform a more complete flip processing. The method is as follows: When using GPS to give time, if the number of weeks is 0, the local time period will be estimated to determine whether the GPS week count is reversed and the corresponding processing is performed.


Using the signal simulator, the setup time is 2019-9-29, and the test environment is as follows: