Lap display drifts - is this a GPS problem?

evanbottcher
Posts: 6
Joined: Tue Apr 14, 2009 12:09 pm

Lap display drifts - is this a GPS problem?

Postby evanbottcher » Tue Dec 14, 2010 6:08 am

Hi folks,

I've never had particularly clean data from my DL-1 - each lap varies by tens of metres, well outside the bounds of reality. Here's a couple of examples:

Image
Image

The car is a 1977 Alfasud Ti. DL-1 is centrally mounted on an alloy plate on top of the transmission tunnel. The GPS antenna is outside on the roof - on the left side.

However on the weekend my friend strapped the DL-1 into his Alfa, antenna stuck in the same place. Magically his data seemed to be totally accurate! Here's an example:

Image

How do I check from the data that I'm getting GPS lock? Number of sattelites?

evanbottcher
Posts: 6
Joined: Tue Apr 14, 2009 12:09 pm

Postby evanbottcher » Tue Dec 14, 2010 6:11 am

Here's a link to download the data:

http://evan.bottch.com/wp-content/uploa ... rchive.zip

Run 6 is the data from my car.
Run 9 is the data from his car which appears more accurate.

Rattie
Posts: 4
Joined: Wed Mar 24, 2010 1:52 pm

Postby Rattie » Tue Dec 14, 2010 2:06 pm

Just a thought, could there be interference in your car that's not present in your friend's? I'm thinking particularly along the length of the downlead. I remember reading somewhere that running the GPS downlead with video feeds can cause GPS signal degradation. Over the break I'll be rerouting my cables to avoid thid kind of thing.

Martyn

evanbottcher
Posts: 6
Joined: Tue Apr 14, 2009 12:09 pm

Postby evanbottcher » Wed Dec 15, 2010 1:43 am

"downlead" - do you mean the lead from the GPS antenna? Both cars are pretty basic, mine a 1977 Alfasud, his a 1973 Alfa 105 coupe - neither has particularly much electronics. The GPS lead doesn't run near anything interesting from an electronics pov.

Perhaps I should try a different source of 12v, direct from the battery (I'll have to put a fuse in of course)?

Is there a way of measuring electrical interference?

Support

Postby Support » Thu Dec 16, 2010 10:28 am

Hi,

Are you in Australia by any chance?

Could you email me the data please, sent it to andrew@race....

and I'll take a look and offer advice on the problem.

Kind regards,

Andy

Parry
Posts: 8
Joined: Sat Jan 22, 2011 5:37 am

Postby Parry » Tue Jan 25, 2011 12:41 pm

Was this issue resolved, I am experiancing the same issue with Wakefield Parry in Australia.

I have a support ticket open for a few weeks but no answer as yet.


Return to “GPS-specific questions”

Who is online

Users browsing this forum: No registered users and 1 guest