[OZAPRS] GPS rollover week

Liz liz at billiau.net
Sun Mar 3 10:00:11 AEDT 2019


QTR Sat, 2 Mar 2019 20:27:33 +1100 Liz QTC

> I'm using a Garmin GPS 18-PC in the car.
> I have just been looking to see if and when this will be affected by
> GPS rollover week.
> 
> I'm sure others on this list are using the same device, and also have
> cut off the serial socket and can't easily upgrade the device.
> 
> Has anyone got information to share?
> 
> Liz
> VK2XSE
> _________



I have managed to determine that the device is susceptible, allowing
10 bits for the storage of the GPS week. (1024 possible weeks)
Manufacturers added code to alter the start date for a device, so
devices may not fail at the time, but at a time up to say 19 years
after production.

I have emailed Garmin to request details on the likely date of failure,
which could vary by serial number, and ask for firmware to do an update.

Liz
VK2XSE

refs
https://www.spirent.com/blogs/positioning/2018/january/gps-rollover-week
https://www.gps.gov/cgsic/meetings/2017/powers.pdf
http://static.garmin.com/pumac/425_TechnicalSpecification.pdf


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Liz
VK2XSE


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