GPS Drift Correction & Overlay Adjustment

Discussion and support for i2 Standard and i2 Pro applications

Re: GPS Drift Correction & Overlay Adjustment

Postby toby on Sat Oct 18, 2008 2:52 am

Yes WAAS is available in Europe and yes it does offer some improvement - if you can get consistant lock onto them. From previous experience with other systems, this has been difficult. As far as I know there is no way of knowing in the I2 logged data if any WAAS satellites are being recieved but maybe someone can correct me on this,
M-Tech - MoTeC Dealer UK
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Re: GPS Drift Correction & Overlay Adjustment

Postby AlanB on Mon Oct 20, 2008 11:40 pm

The 10hz and 20hz systems which we sell output the GPS satellites in view but also, and crucially, the GPS fix status. The fix status is 0 (none), 1 (GPS), 2 (DGPS) and this can be logged but the CAN template needs to be setup in dash manager to suit (as it isn't in the default template).

ID 4741
Channel GPS Fix Status
Variable 6
Multiplier 1
Divisor 1
Adder 0
Modulus 32767

This is all part of the standard $GPGGA message which includes lat, long, fix status, number of satellites, HDOP, altitude etc.
Alan Bell
MoTeC Europe Ltd
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Re: GPS Drift Correction & Overlay Adjustment

Postby JayDee on Wed Nov 26, 2008 10:11 pm

The GPS unit we used for our testing was the MoTeC USA 10Hz unit via MoTeC Eu, even when it was fully locked on, with up to 10 sats we experianced a significant level of drift over a 20 minute period. (Paul Ricard, Southern France)
I think that if we wish to improve our overall accuracy and reduce drift we would have to look at using a local differential beacon.
I would agree that being able to move the 'refference' track outline would allow the user to create almost any driven line. However by applying a little judgment it would allow a user to make adjustments to remove the significant drift experianced over the course of a race weekend. Assuming they are not in traffic, our drivers will consistantly passover the start finish line in much the same point.

Due to drift, at this time the repeatabilty offered (without using a local beacon point) is too low for us. There is not a simple way to adjust for the drift in the software. So for the time being it has been put on 'nice ideas' shelf and we shall probably revisit it in the future to see how it has progressed.
BTW, In the small amount of time I have had with higher end RaceLogic solutions...driven lines can be consistantly overlaid throughout the day, Im not looking to compare system with system but that is my experiance.
Cheers, J.
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