The Y2K bug of GPS is nearly upon us. There will be a 60ms jump made on July 1. If you're running older receivers, be sure you have your firmware updated. For Trimble specifically, you'll need at least version 2.32 or 3.82 depending on which receiver you have.
Are you sure about this? There have been several leap seconds since we bought out Trimble R8's and have never had to do this previously?
The announcement I got from Leica is that you will only see an issue if you are tracking at midnight on the night of the leap second. If you turn your receiver off and back on you'll be all set. During the leap second our equipment will stop tracking GLONASS. But if you're not working during that exact time (at midnight) then you won't really be affected. If you're above firmware version 5.50 then you won't have a problem anyway.
I don't know how the leap second affects GPS units. I do know that technically, in the time laboratories, the leap second is added on to the end of June 30; it's name is 23:59:60 UTC. (I'm sure all kinds of different approximations are used in various systems outside the time laboratories.) It is observed at the same instant throughout the world, so it would be 4:59:60 PM Pacific Daylight Time.
Could someone explain what 60 ms has to do with it?
Keep in mind that is midnight UTC which depending on your location, may be the middle of the work day.
I believe early model R8 (Model 1) may be effected. I'd look at your firmware version, no matter what receiver you're using. Measure twice, cut once.
I think there is a 60 msec value somewhere in the relationship of kinds of time, but the leap adjustment is always exactly 1 second.
GPS doesn't know anything about this. It just keeps on going continuously, as do the atomic clocks. It is the rest of the world that adjusts its time by 1-second increments to keep in approximate agreement with the earth's rotation.
How that affects your software could vary.
Straight from my dealer's keyboard
"Trimble has not released any firmware to correct for the leap second change as of yet. The change is being monitored and firmware may be released prior to or after the change dependent on its effect on gear. Any new firmware releases will be announced on our blog: Blog: Trimble Surveying » Duncan-Parnell ."
Further more, based on the comments above and other things I have read I believe (my opinion) is that only receivers that will be operating at that time need to worry about this. This could be a real problem for CORS stations that are not ready for it.
There is a scheduled time change that will extend the month of June by one second that was mentioned in January.
GPS Leap Second Occurs On June 30, Not July 1
The clock on June 30 ticks:
23:59:58
23:59:59
23:59:60
July 1 Begins:
0:00:00
0:00:01
and is completely normal.
Maybe I will run a receiver through midnight 6/30 to 7/01 just to see what ticks.
Paul in PA
GPS Leap Second Occurs On June 30, Not July 1
> The clock on June 30 ticks:
> 23:59:58
> 23:59:59
> 23:59:60
> July 1 Begins:
> 0:00:00
> 0:00:01
> and is completely normal.
>
> Maybe I will run a receiver through midnight 6/30 to 7/01 just to see what ticks.
>
> Paul in PA
I've had many conversations with laypersons and experts concerning UTC time vs. GPS time, the latter which is presently ahead of UTC by 16 seconds and will be ahead of UTC by 17 seconds come July. UTC and GPS time were synchronized on 06 January 1980. GPS time since then is strictly linear based on atomic clocks, but UTC is based on actual astronomical earth centered observations (mean solar time), so must be adjusted periodically for changes in the Earth's rotation rate, to keep astro observations (your local time, sunrise, sunset, etc.) accurate.
Since GPS time has *nothing to do* with UTC leap second adjustments, positioning and precise timing (+-100 nanoseconds) from the satellites will not be affected by the upcoming leap second. But, here's the stinker: the satellites broadcast the leap seconds offset only every 24 minutes, so for converting to UTC for display purposes or whatever, your receiver could be off by a second for up to 24 minutes. This is not an unreasonable glitch, the last leap second was introduced in 2012, so GPS receivers which do the conversion have done so accurately for +-3 years, and will do so accurately once you've run a receiver for more than 24 minutes after July 1st.
The biggest stink was the GPS Julian date rollover in 1999:
"GPS System Time will roll over at midnight 21-22 August 1999, 132 days before the Year 2000. On 22 August 1999, unless repaired, many GPS receivers will claim that it is 6 January 1980, 23 August will become 7 January, and so on. Accuracy of navigation may also be severely affected. Although it appears that GPS broadcasts do contain sufficient data to ensure that navigation need not be affected by rollover in 1999, it is not proven that the firmware in all receivers will handle the rollovers in stride; some receivers may claim wrong locations in addition to incorrect dates.
Didn't happen. I ran a Trimble yellow brick receiver with a choke ring antenna on a first order monument (Hayes CA) for 12 hours during the *rollover event* in 1999, sent the data to Trimble and they verified the data was within centimeters. Agreed some handhelds may have blown up, but these days every GPS receiver (consumer and professional) will handle the leap second in stride.
The May 2015 issue of GPS World on page 8 has an article about "A Leap Second---One More Time!"
Interesting but more historical. If you go to www.gpsworld.com and then type in the search box Leap Second it will pull up 31 articles on the subject. One said some units could not handle the Leap Second.
Happy hunting.
JOHN NOLTON
Tombstone, AZ.
