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TTN2 going backwards
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Dave
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Are you running in SiRF ? If so, switch back to NMEA.
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superkev6969
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Hi
Anyone know what the expected BT range should be.
My TomTom GPS BT-2215 works fairly well in the car but signal strength gets low at over 6feet in my kitchen.
There seems to be a few problems with th 2215/ TomTom with lockups. fail to restart, screen wont turn on. I hope sombody somewhere is working on these.
Thanks in advance
Kev
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DavidW
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Having had a chance to think further, what would be really helpful would be if, when it's malfunctioning, someone could capture a log and send it to me so that I can take a look. I can then take a look and see precisely what is missing (or incorrect) in the data. A short log when it's working perfectly would be helpful for comparison purposes!

If you go into the GPS status screen, and go to the third tab, there's an option there to record a log. Record for a minute or so - I don't need any more data than that - then press the stop button.


The GPS driver should tell you where it's put the file - it's configurable at the top of the Log page (default is \My Documents\GPS Log\). You can label the log file with its contents using the Info button.

You should be able to transfer the file(s) to your PC (using the Explore feature in ActiveSync, select the file(s), press CTRL and C to copy, then in a folder on your PC, press CTRL and V to paste).

If you can then email the file(s) to me (david <at> wood2 <dot> org <dot> uk - with the appropriate substitutions), I can take a look and see what is going on. The log file contains the raw data that the TomTom GPS driver is receiving from your GPS hardware.


I hope that makes sense - if not, I'll try to clarify.



David
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DavidW
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

I can't think that how you select your route is going to make any difference.

I'm truly puzzled as to how this is happening - I can't think of anything else relevant at the moment!



David
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phinea
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Daid

Yes - the compass was fixed pointing N last time it happened (didn't particularly notice on earlier occasions).

For your information - the compass again jammed pointing North today though the route was shown correctly, distance decrementing etc., (with the GPS receiver set to NMEA etc.)! I got it to revert to correct orientation by disconnecting the power for a few seconds and then when it reacquired, the compass and route display corrected themselves. I begin to suspect that this may tend to happen more using the 'Navigate to' function after selecting the destination rather than selecting both start and destination and then going to Navigator mode, but I could be wrong, I'll keep a watch out.

Cheers,
John
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DavidW
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Just one thing to add - I suspect that the problem is not so much backwards screen information as the direction information being returned always being 0 degrees. Switching on the compass in the Navigator screen will show this - are you shown as heading due north when the fault has occurred?


I believe this is the default in the TomTom GPS driver if the VTG sentence is missing from the NMEA input stream. My suspicion is that, under some circumstances, the GPS driver is sending a command that the Evermore chipset interprets as turning off the VTG sentence! Selecting "NMEA 0183v2 4800" should stop the TomTom GPS driver from sending any commands to the GPS hardware.



David
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DavidW
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

It seems as if my belief that we're talking about Evermore chipset GPSes is true, then.

Alan has a HI-203E - as Dave says, that's a Haicom unit, which uses an Evermore chipset. John knows he's using the same chipset.


So far as lag goes, I can't see why there should be any difference between "NMEA 0183v2 4800" and any other setting. The GPS will only be producing position updates every second in NMEA mode.

The only difference between "NMEA 0183v2 4800" and the "Haicom GPS" setting is that the TomTom GPS application won't be trying to send any configuration commands to the GPS (which it probably won't understand, as I think that setting sends SiRF commands which could confuse an Evermore chipset GPS).

My suspicion is that the GPS application's attempts to configure the GPS hardware is causing the problem. As I posted earlier, I don't believe there's any settings in the TomTom GPS application for Evermore chipset GPSes, so using the "NMEA 0183v2 4800" setting, which sends nothing to the GPS, seems best.


A completely separate issue is that an Evermore chipset may be inherently more laggy in direction and speed information than a SiRF chipset running conventional firmware. This is of particular interest when you think about the differences between conventional SiRF and SiRF Xtrac firmware.

Take a look at my comments in this thread. As I mentioned there, SiRF Xtrac firmware gets better signal performance at the expense of lag in some cases. I also quoted an assessment of the Evermore chipset as having better signal performance compared to standard SiRF firmware. If that assessment is correct, could it be that the Evermore chipset gets its slightly better signal performance at the cost of some lag - a less extreme version of the trade-offs between standard and Xtrac SiRF firmware?

Only a side by side comparison of a SiRF receiver running conventional SiRF firmware and an Evermore based receiver will determine this. This could be a good thing for the PocketGPS team to do in the light of their ongoing HI-303MMF review project. The HI-303E is cheaper, and I don't think the team have done a full review of an Evermore chipset GPS yet.


Meanwhile, my suggestion to all Evermore chipset users is to select "NMEA 0183v2 4800". Hopefully we can confirm that that solves this problem.

It might be helpful if Dave or another staffer can somehow mark this thread as being potentially relevant to anyone who has, or is considering, an Evermore chipset GPS, particularly with TomTom Navigator 2.



David
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phinea
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

So far so good...

I followed DavidW's advice and reset the receiver to "NMEA 0183v2 4800" and have had a couple of journeys without a problem. Not that that's definitive as this has been intermittent. I have a busy week coming up - including setting off from home tomorrow morning in what TTN will probably advise is the wrong direction.

Could it be that in this setting that the device is slower to provide position updates. I noticed that the display was showing turnings slightly behind my actual position which could be confusing in city street navigation?

Alan - you can find a pic of the USB version here
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Dave
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Hi Alan, it's a Haicom 203E.
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AParky
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

From John's post earlier it looks like my GPS receiver is the same as his. I think we are getting nearer to the answer which units are causing the problems, but not why.

To be continued !

Alan
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AParky
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Dave,

I looked at the photo's and it appears to be none of them. I have posted a couple of pictures of the actual unit to you. The label on the bottom states HI-203E, but no manufacturers mark.

Alan
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Dave
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Alan, if you can send me a photo of it, I can tell you which GPS you have, or you might be able to work it out from looking at the following photos. Which company did you purchase from ?
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AParky
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

David,

How would I find out what GPS I was using. I bought TT2 as a package, but the GPS is not the standard TT2 they use. It looks like the company I bought the system off make up their own hardware package, I bought the full system with car vent clip for about 150 new. It looks now that it's cheap because of the GPS receiver. Having said that, it works great other than this anomoly. Would a photo of the unit help identify.

Regards Alan
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DavidW
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Hmm - this could be of relevance to the recent discussions about Evermore versus SiRF chipsets - John has an Evermore based GPS mouse (Haicom model designations ending in E are Evermore chipset).

That removes SiRF from the equation (Dave and I did a lot of musing about that in the original thread) - Evermore GPSes can't talk the SiRF binary protocol. However, it could be that the wrong setting is being used in the TomTom GPS driver, leading to this strange behaviour.


Looking back at the old thread Alan referenced, the one thing he didn't say is what GPS he was using? Was it also an Evermore based one, I wonder? If so, this could be an Evermore bug.


Precisely which protocol the "Haicom GPS" driver talks to the GPS is unclear - but I think it's SiRF. Certainly the "Reset GPS" functionality works correctly with "Haicom GPS" selected when using my SiRF based HI-303MMF. I don't have an Evermore based GPS to try it with.

This suggests that Evermore chipset GPSes should be run as "NMEA 0183v2 4800" (and not "Haicom GPS") unless we can track down something that is definitely Evermore based in the list. I've just been through the entire list in GPS 2.08 with Google and I can't find anything Evermore based in the list (though I can't find chipset details for the Holux GM-200 or the Pharos iGPS-180).

The only wildcard here is if somehow the "Haicom GPS" setting attempts to recognise whether the connected unit is Evermore or SiRF. I reckon this will not be the case as you would have expected something definitely Evermore elsewhere in the list.


So:

Alan - it would be good to know what GPS you're using.

John - try setting your GPS driver (second tab - you'll have to remove the tick in the box before you can change the options) to "NMEA 0183v2 4800" and the appropriate COM port.


Does that get us any further?



David
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phinea
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PostPosted: Sun Sep 14, 2003 8:04 am    Post subject: TTN2 going backwards Reply with quote

Thanks guys...

Dave - I can't see how to change the GPS settings (I have a HIACOM 203E receiver). There's nothing I can see in TTN options nor on the GPS status.

Alan, I've had as similar problem as you with the compass locking on North but the route following my direction of travel correctly just offset by the deviation from North. Could this be related?

One thing I have noticed is that on a few times when the 'backwards' problem it has occurred when I leave home, having set a destination but TTN shows what is obviously the wrong first direction (i.e. S instead of N down my road). When I set off N TTN has then faffed around endlessly recalulating telling me to turn into side streets to turn around etc etc. and all the while the display shows the direction arrow pointing in the opposite diredction to the small arrows indicating the route & with my destination approaching me from behind, as it were. I've tried the power off/on with no luck. I can't figure if the receiver has a battery itself or not, by the way.

Could it be to do with the fact that I tend to leave the receiver powered on when not in use and that it has some internal memory which recalls the direction I used when I last arrived and parked at home?

PS - I upgraded the GPS driver and it handily reset TTN to factory defaults wiping out all my favourites, last visited's etc. Thanks TomTom - nice one!

Any help appreciated
John
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