Thread: Speedo vs GPS

Originally Posted by rocket rod

I use a Samsung Galaxy Tab about 4 years old with built in GPS ....

I'm currently using a Galaxy Tab2 (7").
Good unit. Only reason I've kept with it was that it worked so well.
No reason to dump something that works!
(I'm a GPS geek/freak/habitual updater!)

I'm 99.999% confident that on an open road(no matter the weather either) .. you could safely put money on the GPS and Ozi being more true than the Landrover's odometer.

Sorry can't help with info about how to readjust settings in the car.

ps. have you looked at or played with the Ozi Screen designer?
If you don't know of it, or what it does:
Small peripheral program you load onto a PC(Windows!).
You're configure the screens you want on the device running Ozi.
I've changed all the default screens, added more info to most, added a few more for specific purposes.
One of the ones I use regularly when on a trip is one screen specifically set up with odometers.
I've set three of them, one I use for the total trip distance, another I use for fuel fills(estimate to empty), and third one for keeping distance tabs on small bits of tracks here and there.
First two are self explanatory, but the third is simple.
Get onto some obscure track somewhere, only with the knowledge that at 12.5klms there is a turn off.
Instead of relying on depleted grey matter to remember a klm reading I know I'll forget, I use this third trip meter.

On my recent trip, I used that second trip meter to record all fuel distances.
5 fills for the trip, all Ozi trip meter readings were exactly 8% more than the D1's odo.

ps. the speedo is pretty much spot on, only showing 1km/h faster than actual.
Actual = both Ozi on the Galaxy Tab and the overhead gantry's in some selected locations on Vic freeways.

Originally Posted by LRD414

My Dad would love to go back to Mickey T's. What size/spec are you running Brian?

Cheers,
Scott

STZ 265/60R18 Scott. Very happy with them.

Originally Posted by AK83

I'm currently using a Galaxy Tab2 (7").
Good unit. Only reason I've kept with it was that it worked so well.
No reason to dump something that works!
(I'm a GPS geek/freak/habitual updater!)

I'm 99.999% confident that on an open road(no matter the weather either) .. you could safely put money on the GPS and Ozi being more true than the Landrover's odometer.

Sorry can't help with info about how to readjust settings in the car.

ps. have you looked at or played with the Ozi Screen designer?
If you don't know of it, or what it does:
Small peripheral program you load onto a PC(Windows!).
You're configure the screens you want on the device running Ozi.
I've changed all the default screens, added more info to most, added a few more for specific purposes.
One of the ones I use regularly when on a trip is one screen specifically set up with odometers.
I've set three of them, one I use for the total trip distance, another I use for fuel fills(estimate to empty), and third one for keeping distance tabs on small bits of tracks here and there.
First two are self explanatory, but the third is simple.
Get onto some obscure track somewhere, only with the knowledge that at 12.5klms there is a turn off.
Instead of relying on depleted grey matter to remember a klm reading I know I'll forget, I use this third trip meter.

On my recent trip, I used that second trip meter to record all fuel distances.
5 fills for the trip, all Ozi trip meter readings were exactly 8% more than the D1's odo.

ps. the speedo is pretty much spot on, only showing 1km/h faster than actual.
Actual = both Ozi on the Galaxy Tab and the overhead gantry's in some selected locations on Vic freeways.

AK83

Interested in your screen designs for Ozi as I use the Screen Designer app myself so PM me if you would like to swap ideas.

As to your summary, I agree that the car's odo is probably at fault all I need now is some way of correcting it? As someone said here before "I wonder what would happen if there is a warranty claim" given that the car reaches the 100,000km before it's actually gone that far!

Did you guys even read the posts from Graeme, me and others that the D4 odo is accurate and the speedo is out deliberately by a set amount? Or the posts re the inaccuracies of GPS distance measuring as you are doing?


I can only repeat, do a proper check of distance, independent of a GPS, to determine whether the odo is accurate or not. You can't just say it is inaccurate when you haven't properly measured the accuracy against a known distance.

Bob

I have read the comments by others here but not one of them "prove" they are correct. Can you show me documentation that says the distance markers on the roads are accurate? I used to be a surveyor and I have a reasonable understanding of these things. For instance what happens when Main Roads realign a road and cut out corners thus making the total road length shorter. Do they re-position every sign on that road so their distance markers are correct? Nope. They are guide only. Everyone on this forum says the speedo is inaccurate but everyone also says by varying amounts. So who is correct and how can they prove it? VW had very good emission standards until recently remember!

To try and clarify the situation I've asked Main Roads WA and the creator of Oziexplorer for some comments, so I'll wait and see.

I'm glad you read them at least Rod. I thought you must have been selectively reading posts to suit your point of view.


I have checked mine against distance posts several times, in WA and elsewhere in Australia, just because I can. I've checked individual post distances and also over long distances. Every time the distance is spot on. Are all mile posts around Australia going to be out by the same amount as the D4 odo? Obviously if there was a sudden difference between the odo and pegs the distances may have changed on that piece of road but I am talking about most roads where things haven't changed much in a fair while.


Graeme has looked at the settings of the D4. The odo has been set at the factory to be accurate and the speedo has been set to read higher than the actual speed in accordance with the ADR's by a specific amount. This difference is what most people experience, indicating that the D4 speedo is also accurate within the parameters set by LR. How can you therefore categorically say in your post that the D4 odo is highly inaccurate?


You even have larger than standard tyres which means the odo is actually measuring lower distances than what the car is travelling, not higher.


I will be very interested in your findings from MRWA and Ozi Explorer and the results of your own more meaningful checks on the odo using your surveying skills!

Originally Posted by BobD

Did you guys even read the posts from Graeme, me and others that the D4 odo is accurate and the speedo is out deliberately by a set amount? .....

So what you are saying here is that every single one of the hundreds of thousands of D4's ever made, the odo is dead accurate, and that's that!

But the advice to use the roadside distance markers as a guide is perfectly valid.
That's what I do.
They may not be 100% accurate if viewed upon as a surveyor, but as long as they're accurate enough, or can validate one set of readings, then that should be good enough.
So the point isn't if the 50k sign to The Black Stump is actually exactly 50klms from the place called the Black Stump, as long as they are confirming one reading or the other, that's what's important.
My recent trip was from Melb to Maitland via Sydney 100% all freeway. Then back via Bathurst, and many back roads, before hitting the freeway again at Yass.
Ozi and the distance markers all said the same thing, car was out.
I know to use Ozi as my guide to "the next town" .. and importantly if I have enough fuel to make it.

I think that many of us have the intellect to understand that the odo and the speedo readings can differ on any vehicle, that's almost a given situation. But using the law of averages, I don't think it's improbable that at least one D4 somewhere in the world(maybe even in WA!!) has an odo that may be slightly out of whack.

@ rocket rod.
I'll shoot you a PM as soon as I can get a few moments spare.
I just bought the Hema + additional maps collection from Ozi(worth the $, if you can justify it!), and I'm trying to configure which maps I want on the PDA(64Gig card, but still trying to keep it slimmed down).
+ installing a snorkel, + doing some errands for siblings, + trying to get some R&R before I'm back at work .. + + kids!

Some valid points AK83. However comparing a D1 odo to a D4 odo is a bit misleading. When I read your first post I was assuming you had a D4, not a D1.


Note that in your last post you said your D1 was 8% under the GPS and mile post distances but the OP's D4 odo was reading well over the GPS distance. In your first post on the subject you said the speedo was reading 8% above the GPS. Which one is it?