TomTom 940 Dead Reckoning/EPT - does it work?

[snoopstah]

Hi guys,

I had opportunity to test out my TomTom 940's EPT today, and to say I was unimpressed was an understatement.

I had parked in a multi-storey car-park and so had lost signal when I entered. I expected to see the position update or move as I moved around in there but there was nothing. Thinking this was because I wasn't on a road, I wasn't too worried.

However, when leaving the car park it once again gave no indication of any sort of dead reckoning taking place, and did what my old PDA did, which was to not get signal/update the position until about 30 seconds after I got sky visibility, by which time I'd had to make a couple of decisions on roads and turnings to take.

Surely this is a situation where EPT should at least help? I've used an Alpine built-in satnav system with dead-reckoning and it does exactly what I'd expect, giving directions as soon as I leave a covered carpark (and indeed often before!)

I also seem to recall from reading the manual that an icon should be displayed when EPT is in use, but I didn't notice this either. Does this mean that EPT might be somehow disabled?

[jmcmtank]

I find the EPT works fine, but I've never used it off-road. As for you leaving the car park, the manual says,

[Hughesynights]

Off road is a lot tougher for EPT.
On road, it only has to be accurate enough to tell if you have taken a turning or not. So distance (acceleration and deceleration) and turning (yaw rate) don't have to be too accurate.

My Honda built in nav is quite accurate off road (e.g. in a multistorey carpark). But it gets an accurate speed reading from the car, as well as a gyro yaw sensor.

I don't really know how good EPT is, or how to test it!
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920T Navcore 8.300; Western & Central Eu 815; NA 815; TTS v7
New Live 750

[DennisN]

I have EPT on my GO920 and not on my GO720. Without it, the 720 performs far better. The EPT icon on mine is a tiny thing, bottom right. It cuts in at the slightest provocation - notably if I'm running a roundabout underneath a motorway junction. I also have a HTC running TT Navigator 6. Of the three devices running side by side on my windscreen, the HTC and the 720 regain signal after a tunnel as fast as, if not quicker than the 920 with EPT. They also keep pace with my travel just as well as the 920 - all three come out of the tunnel together. For my money, it's a pig in a poke. Maybe on the 940 it's better, but I wouldn't expect so. But I wouldn't expect anything to work with a multi storey carpark.
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Dennis

If it tastes good - it's fattening.

Two of them are obesiting!!

[MrT]

I have found that the 940 EPT works fine in tunnels and detects stop start traffic and it also continues to warn about SPECs cameras in the tunnel roadworks (M25 Bell Common). The satellite bars are replaced by the small round icon when this works. I also noticed that the tunnel section of road was marked in grey before I entered the tunnel so I do not know if the map told the EPT to activate as I was in a tunnel rather than activating due to the loss of satellite signals.

The 530 in the same place assumes a constant speed in the tunnel and after a while gives up.

In a multistorey car park it sort of worked on the way up as in the map kept rotating but just sat looking for a signal on the way out and got one as soon as I got onto the road, which is what I would expect.
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Drivelux

[Tomo]

I have no experience of the EPT in TT units but had a built in satnav in my Navarra that had a Gyroscope in the control unit.

That seemed to struggle a little more in a car park and I always assumed it was due to been lots of turns and very little straight bits.

Steve

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