GPS Satellite Reception Time Out

[ccplim]

Let me show you the kind of errors we will get if we try to acquire satellites on the move.

Hi Bro,

Was this captured when you first power up your unit? I have never try to accquire satellites while on the move so I can't comment much on that part.

On the other hand, it came across my mind that I have actually managed to captured a track log on my 60CSx a few months back when I was travelling in KPE. The satellites resumed pretty fast when I exit from the tunnel and the points doesn't seem to "jump" much (as you can see from my screen capture attached below).

[Zeus73]

Was this captured when you first power up your unit? I have never try to accquire satellites while on the move so I can't comment much on that part.

On the other hand, it came across my mind that I have actually managed to captured a track log on my 60CSx a few months back when I was travelling in KPE. The satellites resumed pretty fast when I exit from the tunnel and the points doesn't seem to "jump" much (as you can see from my screen capture attached below).

If you look at your track log carefully, the signal was drifting towards the right for 5 points before it stabilized.

Yes, the track log was captured when I first power up for today. But my nuvi got this HotFix thing, so technically, it's not really a cold start. If it's a cold start, I won't be getting track log for that section of the road. Should be still searching for satellites.

I got another example for warm start. This one is from the return trip after shopping/dinner.

PIC00007.jpg

[winwintoto1234]

4) It's a good observation of yours Zeus73. However, it doesn't explain why I can navigate through when using Garmin 76CSx but not with GMXT. All are using MFM map, albeit 76CSx is added with SLA postcode layer. Maybe I chose Show location on roads for GMXT while 76CSx (which is my boat unit), shows location at GPS location. I'll change it for the GMXT just to see on Monday.

Probably this explains the difference between a device specially meant for navigation (Garmin 76CSx) and a device which is meant for making calls with additional GPS function.

Similarly, you don't expect your phone to play same sound quality with your mp3 player and capture same quality of photo with your digital camera, do you?

[ccplim]

If you look at your track log carefully, the signal was drifting towards the right for 5 points before it stabilized.

Yes, cos that was the part where the unit start to resume satellite reception after I exit from the tunnel and it was trying to narrow down to the 'correct' accuracy (from 60+m down to about 3m)

[cruiser]

Yes, cos that was the part where the unit start to resume satellite reception after I exit from the tunnel and it was trying to narrow down to the 'correct' accuracy (from 60+m down to about 3m)

Both your units are responding to the settings you had earlier programmed for and again, time is needed as you gradually appear from the tunnel in accordance to the speed you drive and there is again the processor speed that differs from either unit.

[LLCC]

This morning, GMXT works well, navigating throughout the the whole stretch of KPE from Tampines entrance, exiting at Tg Rhu and continuing through to Keppel Rd!

Here's what is different in my set from last tested:

1) MFM v1.66
2) Show location at GPS location.

To establish if it was due to changes in the map or system setting change, I'll eliminate one tomorrow (use back old MFM map) and test again.

LL

[Zeus73]

Your problem is intermittent one. It's depending on the GPS signal strength and accuracy.

I don't see any changes around that area for MFM v1.66.

[cruiser]

It could also be due to the transponder speed in his unit. Some respond slower than it should... a smallish defect but nothing serious for overreaction or concern.

[LLCC]

Your problem is intermittent one. It's depending on the GPS signal strength and accuracy.

I don't see any changes around that area for MFM v1.66.

Yesterday, should be one of the poorest days to look for satellite strength. Don't know about accuracy, but yesterday was heavily overcast and pouring with rain. Most, if not all of the other days tested IIRC, were clear and fine.

Anyway, I continued testing today just to see what is the vital ingredient that made it work. So I used 2 sets simultaneously with the following settings:

a) N95, GMXT ver 5.00.50s60.9.
Map: MFM v1.62 (non SLA postcode)
AGPS: on
Show location: At GPS location
Weather: Cloudy
Result: GMXT recalculated route but failed to continue navigation after exiting Tg Rhu exit. (I heard "recalculating" when I exit, but nothing else. At the top of Shears Bridge, I noticed this set had gone to map mode).

b) N96, GMXT ver 5.00.50s60.9
Map: MFM v1.66
AGPS: Off
Show location: At GPS location
Weather: Cloudy
Result: GMXT recalculated route and continued navigation after exiting Tg Rhu exit till the destination is reached.

Observations:
N95 GMXT logs on to satellites marginally faster than N96 as I heard the "recalculating" from N95 first. However, this is just marginal, as it happened almost together, ie, before N95 can finish speaking the word "Recalculating", N96 had already started to recalculate.

Despite the overcast sky, Satellite log-on at tunnel exit was fast (less than 1 second from exiting tunnel). So was it a new map version fixed the problem? Or changing Show GPS Location setting to "at GPS location"?

Tomorrow, I'll change 1 variable (load MFM V1.66 into N95) to see again.

LL

[LLCC]

Had not gotten any success in keeping GMXT in navigation mode ever since my 2 days of success earlier this month.

In trying, I've done the following, but all to no success:
• updated firmware of both Nokia N95 and N96 phones
• Set "Show Location" setting from "on Road" to "At GPS location"
• Activate AGPS
• Update GPS map to MFM v1.67
• Tests done on good weather in the morning (if that made any difference)

In the interim, I had experimented many scenarios and managed to cause the GPS to stop navigation like that encountered when coming out of the tunnel. This is what I did:
• Go outdoors to get a 3D fix.
• Without waiting any longer for more satellites to log on, get indoors and wait till GPSr give the "lost satellite" signal.
• Stick GPSr in and out out of the window to get a weak 2D fix.
• This will cause GMXT to say "unable to recalculate route" and abort navigation.

This morning, I got my first complete navigation from Tampines to Keppel through KPE. Only difference in condition are:
• MFM v 1.68 map
• It was overcast with slight drizzle this morning.

That's all for my observations. Doesn't anyone from this forum encounter the same as me? Of all the cars that take the KPE to town each morning, isn't there anyone using GMXT and navigating?

Let's share your experience.

LL