Topographical map calibration? Help!

[popabawa]

Hi,

I'm pretty new to this GPS lark so please bear with this newbie...

I have an iPAQ 2210 with the Fortuna Clip-On bluetooth GPS which is working perfectly with TTN2 so I'm sure there's no problem with the hardware.

I've been trying out various topographical software over the last few days with the intent on using it for a bit of Geochaching and I'm also interested in trying GPS whilst out running to track my milage & routes.

So, I'm mainly interested in calibrating my own maps as I have no need for the more expensive packages (Fugawi, Memory-Map etc).

So far I've tried the free VITO software with the map manager for calibrating maps. I've also tried out the demo versions of GPS Dash and GPS Tuner which enable calibration on the pocket PC itself.

Is it me being a muppet or is calibrating your own maps REALLY difficult? (I'm using some 1:10000 .jpg's / .bmp's of the local area)

I've had no success with VITO, I can't even get the map to display, I am always out of range, even when I'm demonstrably 'in' the map.

GPS Tuner seems to always think I'm about 50m out.

GPS Dash I can get nearly there, only about 5-10m out.

This is using the same set of co-ordinates (From the Pocket PC) in each bit of software to calibrate.

So my questions are....

Should I expect better accuracy than the 5-10m I've got with GPS Dash?

If so, is there a complete idiots guide to map calibration because it really feels like I'm doing something fundamentally wrong! (but I have no idea what...)

TIA for any advice,
Iain

[lbendlin]

GPS accuracy is about 15 m - down to 5 meters if you're lucky. So what you get with GPSDash is more or less the best you can get. TomTom and other navigation programs are cheating, they are locking to roads and making you think they are more accurate than the 5-15 meters..

If your receivers is in WAAS/EGNOS mode and you actually get a signal then you may get some better results. (that's called differential GPS)
_________________
Lutz

Report Map Errors here:
TomTom/TeleAtlas NAVTEQ

[popabawa]

Thanks for the reply, I appreciate it.

That explains some of my problems then.

Also explains why TomTom doesn't seem to care if it can only see 4 sat's - that's even more impressive than I originally thought!

Sounds like I'd managed to calibrate GPS Dash correctly and done something wrong with the others. I'll have to give it another go to see if I can improve.

I think I've been somewhat mislead by screenshots of these various programmes with tracking lines drawn PERFECTLY down lanes & streets, that'll teach me to be more cynical

I'll try calibrating some maps using streetmap.co.uk and see what results that gives me, that way I can be ABSOLUTELY sure I'm using the same data for each map.

Might give the trial of OZIexplorer a go as well while I'm at it!

Iain.

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