GPS Speed Etrex

MrRob · 14-07-2005, 04:41 PM

I am sure a lot of you guys have the Garmin GPS Etrex
I tested mine out today in my car and I found it to be about 4-5mph out. When I was at 60 it was reporting 55mph. It was reporting 4-5mph below the actual speed when doing above 15mph.
Has anyone ever tested their own like this?
Is there something I am missing?

Rob.

BREN · 14-07-2005, 04:47 PM

may be your car speedo is out by 4-5 mph?

FrenchPhil · 14-07-2005, 04:51 PM

The car speedo is off not the gps.

MrRob · 14-07-2005, 05:21 PM

i guess ill test it in a mates car.

verytricky · 14-07-2005, 07:07 PM

Your mates car will be off as well.

Cars are allowed to be out of accuracy as much as 10%.

They will always under-read, so you can not blame them for points on your licence.

Also, as the car tyres loose tread, they travel less distance in a revolution, but dont inform the speedo of this fact!

Taz · 14-07-2005, 07:16 PM

I dont know if your is the same but my chartplotter is a bit delayed compared to speedo. Just a thought

Taz · 14-07-2005, 07:17 PM

Very Tricky when you taking me out in your Bladerunner? Hint Hint

MrRob · 14-07-2005, 08:19 PM

So you are basically telling me that my GPS is spot on. my car is just wrong.

Captain Chaos · 14-07-2005, 08:32 PM

i'd guess correctamundo.

got your email mate............will turn my brains to it asap

Burty · 14-07-2005, 08:53 PM

Mr. Rob i have the same GPS and also found it to read lower by about 5mph than my car. the funny thing is my car has a computer that tells you average speed and on the motor way (on the flat) setting cruise control at 90mph (speedo) the gps read 85 and the computer read 86 so why cant they get the speedo as accurate????????????

MrRob · 14-07-2005, 09:07 PM

Because they are WANKERS! lol. Have you got MapSource and Blue Chart for yours Burty?

BluFin · 14-07-2005, 09:15 PM

Quote:

Originally posted by MrRob
So you are basically telling me that my GPS is spot on. my car is just wrong.

mmmh I've seen some right errors. sometimes up to 800 Nm out, so much depends on coverage. During the gulf war twaz like a switch when you went over Iran then back on again after can be very selective & . how can i put it.....controlled. Still wating for the russian system but i think thats died a death now?

Burty · 14-07-2005, 09:31 PM

Quote:

Originally posted by MrRob
Because they are WANKERS! lol. Have you got MapSource and Blue Chart for yours Burty?

No, i only use it to see how fast i can go

MrRob · 14-07-2005, 09:33 PM

Well I have a copy if u want it. The info on it is excellent!

Burty · 14-07-2005, 09:37 PM

cheers but not sure if its the same one?

MrRob · 14-07-2005, 09:44 PM

yeh thats the one I have. Blue chart is cool. You just plot your course then load it to your gadget. Job done. you just follow the arrow on screen. Even give you an ETA

MrRob · 14-07-2005, 09:45 PM

You couldnt resist showing the pic with 83.3mph on it! lol

Burty · 14-07-2005, 09:46 PM

only 1 i got

verytricky · 15-07-2005, 12:32 AM

Quote:

Originally posted by MrRob
So you are basically telling me that my GPS is spot on. my car is just wrong.

Yes.

Also, some GPS's will have a slight 'lag' on acceleration, but they will be acurate over flat ground. Up or down steep hills there is more chance of an error. But this would typically be less than 1%

verytricky · 15-07-2005, 12:34 AM

Quote:

Originally posted by Taz
Very Tricky when you taking me out in your Bladerunner? Hint Hint

After Littlehampton. The blade is currently propless - they are in for fine tuning.....

After they come back, I need to do some testing - You can come play then!