Degrading GPS signal...

[Arno]

I had problems a week ago with getting satellites.
In Bangor, leaving the motel, it showed 4 satellites in grey. About five minutes later they turned blue and everything was OK. Three days later, for 15 minutes, coming out of Lake Placid, it showed 10 satellites in grey and finally turned three of them to blue and everything has been OK since (before the next HOME connection).
Either time there were no obstructions at all.

 

[canderson]

I had problems a week ago with getting satellites.
In Bangor, leaving the motel, it showed 4 satellites in grey. About five minutes later they turned blue and everything was OK. Three days later, for 15 minutes, coming out of Lake Placid, it showed 10 satellites in grey and finally turned three of them to blue and everything has been OK since (before the next HOME connection).
Either time there were no obstructions at all.

Ten gray satellites for 15 minutes really does indicate some sort of ephemeris problem. That indicates that your unit was receiving signal from all of those satellites, but did not have the necessary data to correctly interpret the information being received. If your GPSQuickFix had been current and valid, that information would have been used. Instead, it took until your unit could pull together the almanac data successfully from one of those satellites... very much like the first time you turned your unit on after you bought it.

I have to wonder if you may have a bad ephemeris table, too.

 

[Arno]

Ten gray satellites for 15 minutes really does indicate some sort of ephemeris problem. That indicates that your unit was receiving signal from all of those satellites, but did not have the necessary data to correctly interpret the information being received. If your GPSQuickFix had been current and valid, that information would have been used. Instead, it took until your unit could pull together the almanac data successfully from one of those satellites... very much like the first time you turned your unit on after you bought it.

I have to wonder if you may have a bad ephemeris table, too.

The GPSQuickFix was 10 days old.

 

[canderson]

The GPSQuickFix was 10 days old.

They're only good for about a week, and if you were on the move when you turned your TT on as you were leaving Lake Placid (vs. waiting for the fix before you took off), that could explain the slower locks.

Then again, as you were having trouble with it just prior as well, could have been bad ephem data to start with.

How and when did it clear up?

 

[Arno]

They're only good for about a week, and if you were on the move when you turned your TT on as you were leaving Lake Placid (vs. waiting for the fix before you took off), that could explain the slower locks.

Last year they were good for the 22 days that I hadn't connected to HOME. The only glitch then was that between Silverton and Durango it thought I should drive in the mountain side most of the time.

When switching on a route entered through HOME while still in the garage, I always take off without waiting for the fix. Often, while backing onto the street it will say Waiting for valid GPS signal ...

Then again, as you were having trouble with it just prior as well, could have been bad ephem data to start with.
How and when did it clear up?

Don't know about ephem but on the trip home (after those 15 minutes)the unit was switched off an on 5 or 6 times and every time it was OK.