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+--- Thread: Trimble Thunderbolt monitor (/thread-222.html)
Trimble Thunderbolt monitor - VK3ALB - 01-08-2017
Hi All,
My Trimble Thunderbolt monitor is displaying the incorrect date showing 15-Dec-97 today. No alarms evident. I've tried a power cycle but no change. Before I take this further has anyone else seen a similar thing?
RE: Trimble Thunderbolt monitor - VK2ZRH - 01-08-2017
Yes. Adam Maurer. See his postings in the Facebook page VHF UHF Microwave - VK ZL Amateur ham radio.
RE: Trimble Thunderbolt monitor - VK3QI - 02-08-2017
G'day Lou and Roger,
Have a look at the following link:
http://www.ko4bb.com/getsimple/index.php?id=gps-week-rollover-of-july-30-2017-and-thunderbolt-monitor
I guess that the original designers thought that 2^10 = 1042 was a sufficiently large number to cater for the useful life of the unit.
The 3.00 firmware versions date from around 1997, so by allowing for the 1024 figure to be subtracted after December 1997, they thought that another 20 years or so would be sufficient.
What were you doing in 1980 when this all kicked off? I was programming great circle maps and satellite tracking on an Apple 2 with cassette tape software and data saving! How time flies when you are having fun!
I gather there are possible firmware/software fixes, but frankly, I usually know the date (no Alzeimers yet!) so am more concerned that the 10MHz oscillator is being disciplined and the grid square and time are OK.
Cheers
Peter VK3QI
RE: Trimble Thunderbolt monitor - VK3QI - 02-08-2017
Lou,
There is considerable discussion on various blog sites around the world about the problem, which ultimately lies with the fact that the first generation of GPS satellites only had a 10 bit week counter. The next generation of satellites have a 13 bit week counter which will (theoretically) allow for around 150 years!
As one blogger stated:" It's also worth noting that this issue doesn't affect the Thunderbolt's performance as a GPSDO, i.e. providing 1 PPS and 10 MHz signals locked to GPS. It only affects the year. The time and the rest of the date are still correct."
Cheers
Peter VK3QI
RE: Trimble Thunderbolt monitor - VK3ALB - 03-08-2017
Hi Peter,
I understand the effect is limited and has no bearing on the 10MHz signal. Adam was on to it pretty quickly and determined a fixed based on alternate information within the serial stream.