Any date-related GPS problems seen today?

I tried my ancient Garmin eMap a couple of weeks ago - before the epoch rollover. I haven't used it in years and it say with no batteries. It figured out where it was quickly enough. But the date it showed was in 1999. Note this was even before this week's rollover - must be a very old GPS! I used to carry this one when flying as a backup navigation device, since it has a built-in database of towns roads etc at the "right" level of detail. But nowadays Tophat on my smartphone is a much better backup.

My Garmin 76s is not quite as old. I had it stored with no batteries for years. Turned it on a couple of weeks ago and it took an hour to figure out where it was. But then it showed the right date. Stored it with batteries until trying it again yesterday, it got a fix in a few seconds and the date was still correct.

Ah, wasn't saving a bit or two in the data packet worth all this trouble? :-)

I saw several reports of very old Garmin hand-held devices getting their
dates corrupted at this latest epoch, and the owners were able to
correct the problem with a firmware update.

My GPS 12 still has its correct date, but I always leave good AA
batteries installed. I also charge my Cambridge 302 several times over
the winter, for the same reason.


On 4/8/19 3:33 PM, wrote:
I tried my ancient Garmin eMap a couple of weeks ago - before the epoch rollover. I haven't used it in years and it say with no batteries. It figured out where it was quickly enough. But the date it showed was in 1999. Note this was even before this week's rollover - must be a very old GPS! I used to carry this one when flying as a backup navigation device, since it has a built-in database of towns roads etc at the "right" level of detail. But nowadays Tophat on my smartphone is a much better backup.

My Garmin 76s is not quite as old. I had it stored with no batteries for years. Turned it on a couple of weeks ago and it took an hour to figure out where it was. But then it showed the right date. Stored it with batteries until trying it again yesterday, it got a fix in a few seconds and the date was still correct.

Ah, wasn't saving a bit or two in the data packet worth all this trouble? :-)

On Mon, 08 Apr 2019 14:33:53 -0700, moshe.braner wrote:

Ah, wasn't saving a bit or two in the data packet worth all this
trouble? :-)

Newer GPS signal formats have lengthened the epoch to 8192 weeks, so the
next rollover for receivers using CNAV messages should be in 157 years
time, though older receivers should work as long as the Legacy messages
continue to be transmitted using 1024 week epochs and the receiver
remembers (or can be told) the epoch number).

I found this stuff he

https://en.wikipedia.org/wiki/GPS_signals

Its quite an interesting read.


--
Martin | martin at
Gregorie | gregorie dot org

At 23:48 08 April 2019, Martin Gregorie wrote:
On Mon, 08 Apr 2019 14:33:53 -0700, moshe.braner wrote:

Ah, wasn't saving a bit or two in the data packet worth all this
trouble? :-)

Newer GPS signal formats have lengthened the epoch to 8192 weeks, so the
next rollover for receivers using CNAV messages should be in 157 years
time, though older receivers should work as long as the Legacy messages
continue to be transmitted using 1024 week epochs and the receiver
remembers (or can be told) the epoch number).

I found this stuff he

https://en.wikipedia.org/wiki/GPS_signals

Its quite an interesting read.


Most flight recorders receive transmissions on the L1 frequency which does
not include the epoch. L2 and L5 frequencies do contain epoch information.

L1 GPS Engines (a bought-in compenent) have a Real-Time clock which is
maintained by a rechargable battery which is part of the GPS Engine (not to
be confused with any other battery in the recorder).

IF this battery becomes discharged the epoch number is lost.

Oh Honeybad... https://arstechnica.com/information-...ays-groundings

https://eos.org/articles/noaa-monito...gps-y2k-moment




On 4/9/19 9:51 AM, Darryl Ramm wrote:
Oh Honeybad... https://arstechnica.com/information-...ays-groundings

Just downloaded a couple of flights I did yesterday that were recorded on our club's old Cambridge box. Yesterday's flights were flown on 4/14/19, eight days after the recent rollover. The date in the files is 8/29/99, eight days after the 1999 rollover.

The time of day looks right.

Larry

I had 4 Model 20s updated to fix the dead internal GPS battery a couple of months ago. All handled this latest roll-over properly. Same result for the Model 20s I have that have not yet had the internal GPS battery fail and have functioned and had the correct date since initial purchase.

Steve Leonard
Keeper of the Cambridge Model 20s