Testing Procedures for Legacy GPS Gear for Week Rollover on April 6-7
I've been considering what would make a good test to verify that my four Leica SR530 receivers will be able to handle the GPS week rollover on April 7, 2019. I came up with two test procedures.
Prior to the tests I'll collect 4 hours of static data on two points near my domicile and process them with OPUS/OPUS Projects. In the wee hours of April 7 I'll set up on those two control points and start collecting static data at 4:30 a.m. MDT.
If my calculations are correct the GPS week rollover will occur at 6:59:41 a.m. MDT to account for the 19 seconds between GPS time and UTC time. I will let one of my receivers run without interruption until 10:00 a.m. The other receiver I'll stop at 6:58:40 a.m. and store the results, then occupy the point again starting at 7:00:40 a.m.
My LGO software allows the user to merge two data files at the same point (same point ID too) as long as the end time and start time are within 30 minutes. This should allow me to see if there is any time problem when I import the data.
It may be that the receiver that I run continuously until 10:00 a.m. will suffer an error and not be able to store the data. The other receiver may log and store the early data and fail to log anything after the rollover. If this happens it may be due to the almanac in the receiver not being up to date.
I usually collect static data at 5 sec. epochs so I can post-process in LGO. For this exercise I will log data at 1 sec. epochs just to see what happens at the rollover.
My SR530 receivers were manufactured in 1999, 2000 and 2001 and have the latest firmware (ver. 5.1) that fixed a problem in 2009.
Any suggestions on improving my test procedure or alternatives are certainly welcome. It may be that things won't work correctly until the receivers have downloaded almanacs with dates after the rollover.
Sounds like you have thought through your procedure carefully.
But doesnt the rollover happen at 2359:42 UTC ? That's evening April 6 in the US.
Thanks Bill. My senior moments used to be only lapses in memory. Now I see they include basic arithmetic.....SIGH! Maybe I should retire along with my old legacy Leica gear.
Note to self: MDT is -6:00 hours from UTC, not +7:00 hours. Making the start time 3:30 p.m. April 6 will work a lot better than scaring the neighborhood raccoons at 4:30 a.m. the next morning.
ETA: More arithmetic corrections....need caffeinated beverage.
MST is -7, MDT -6 so the rollover is about 6 pm MDT. I didn't consider how much lead time you need.
I took some data last week and the RINEX files say 18 leap seconds, not 19.
I don't think that the ability to span the rollover event is particularly important, I'm interested in learning whether or not my receivers will be functional after the event. My test procedure won't require getting up at an ungodly hour!