Hi Tom, SNAP - we were doing the same experiment at the same time - mine at 43 South in NZ.
However a word of caution for all Garmin 18x owners, you may no get the same results as what Tom and I get ! Here is what my 18x GPS (using firmware v3.90) showed as the week rolled over. I temporarily enabled sentence type "RMF" and "RMT" so I could see what was going on. The first few fields of RMF are: GPS Week Number (0 to 1023) , GPS Seconds of Week (0 to 604799) , UTC Date, Time of Fix (HHMMSS) , GPS Leap second count $PGRMF,1023,604799,060419,235941,18 $PGRMF,0,0,060419,235942,18 $PGRMF,0,1,060419,235943,18 $PGRMF,0,2,060419,235944,18 $PGRMF,0,3,060419,235945,18 $PGRMF,0,4,060419,235946,18 $PGRMF,0,5,060419,235947,18 $PGRMF,0,6,060419,235948,18 $PGRMF,0,7,060419,235949,18 $PGRMF,0,8,060419,235950,18 $PGRMF,0,9,060419,235951,18 $PGRMF,0,10,060419,235952,18 $PGRMF,0,11,060419,235953,18 $PGRMF,0,12,060419,235954,18 $PGRMF,0,13,060419,235955,18 $PGRMF,0,14,060419,235956,18 $PGRMF,0,15,060419,235957,18 $PGRMF,0,16,060419,235958,18 $PGRMF,0,17,060419,235959,18 $PGRMF,0,18,070419,000000,18 $PGRMF,0,19,070419,000001,18 $PGRMT,GPS 18x-LVC software ver. 3.90,,,,,,,,*65 So using version 3.9 of the firmware, the 18x coped well with the "Week Rollover" without any time or date issues. However I then started getting comments from 18x users who said that both the time and date were incorrect after the latest Sunday Roll-over ! Because I had saved OLD versions of the 18x firmware, I was keen to see if I could duplicate what these folks were (post rollover) getting by my "backtracking" my 18x to version 2.8 (circa 2008 vintage) $PGRMT,GPS 18x-LVC software ver. 2.80,,,,,,,,*65 $PGRMF,0,27840,220899,074346,14 $PGRMF,0,27841,220899,074347,14 $PGRMF,0,27842,220899,074348,14 Notice how the date now reads 22-08-99 and the delta between GPS and UTC is 14 seconds (and hence the 4 seconds time error that was being noticed). I thought the 14 seconds delta may change with a new "almanac", but I waited 15 minutes, cycled the power, but the time was STILL 4 seconds out and the date 22-08-99. However I had succeeded in duplicating what others were seeing. I then upgraded my 18x firmware to the "latest" (21st March 2019) version 4.2 $PGRMT,GPS 18x-LVC software ver. 4.20,,,,,,,,*69 $PGRMF,0,29839,070419,081701,18 Both the time and date are now correct ;-) For the GPS 18x PC/LVC, Ver. 4.20, as of Mar 21, 2019, https://www8.garmin.com/support/agree.jsp?id=4055 ----------------------------------------------------------- Garmin 18x Firmware History Changes made from version 4.00 to 4.20: Fixed GPS week number rollover for devices using older hardware. Improved PPS (pulse per second) reliability. Changes made from version 3.90 to 4.00: Improved time keeping. Changes made from version 3.80 to 3.90: Better handling for leap second data storage especially over long periods of non-use. ------------------------------------------------------------ So after all this time, it appears that at last the 18x has resolved some of the issues we have tried to report to Garmin over the years ! So if you have a Garmin 18x, you may want to upgrade the firmware, which will hopefully tell us the correct time and date for the next 1023 weeks ! Regards, Geoff (Christchurch, New Zealand). _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
