how fast

outside · 24-05-2009, 07:10 AM

would you trust the speed reading on a GPS?
are they right? one would think so but how do you really know, short of getting yourself booked for speeding.

KPOJ · 24-05-2009, 07:36 AM

my navman is spot on, just go through one of those speed check things and compare speeds

outside · 24-05-2009, 07:44 AM

Quote:

Originally Posted by KPOJ

my navman is spot on, just go through one of those speed check things and compare speeds

do have any here in the hunter that i know of

EB_5.0_WAGON · 24-05-2009, 09:15 AM

I would trust a GPS/Navman more than i would trust the speedo in the truck i was driving.

Always been accurate never got a fine while i was using it.

cant · 24-05-2009, 09:33 AM

The gps speed seems to be spot on, check mine against the speed cheek 5 days a week, BUT, I no longer trust the speed alert/ speed zone component, got done 17 over after missing a drop to 80 sign on hols last month.

The copper said "thats not an excuse", even though the GPS still showed I was in a hundred zone !

Should be watching where im going and not the speedo all the time, thats a bit hard in vic, 11 fixed speed cameras between NSW border and my home in Geelong !

Vic, "the revenue state"

gtxb67 · 24-05-2009, 09:41 AM

Quote:

Originally Posted by cant

Should be watching where im going and not the speedo all the time, thats a bit hard in vic, 11 fixed speed cameras between NSW border and my home in Geelong !

shouldn't you only need to watch the speedo at the same 11 points each trip - and the road for the rest of the time to see where the mobile ones are

cant · 24-05-2009, 09:50 AM

absolutly.
Being so paranoid about your speed takes the enjoyment out of just cruising these days.

asusdragon · 24-05-2009, 01:10 PM

i use the speed reading on my gps more then i would use the speedo on the car the gps shows me doing 100 and my car speedo would show me on 108. so i use that and havent been booked yet. i think they are pretty accurate and i know the car speedo are out. there designed like that from factory

gtxb67 · 24-05-2009, 02:09 PM

Quote:

Originally Posted by cant

absolutly.
Being so paranoid about your speed takes the enjoyment out of just cruising these days.

that is true - cruising was much more fun 22 years ago than now, i suppose in my case though, we would just drive anywhere and not care about fuel or things breaking - as we get older we care more about funds and with each passing year, we add another year of hating other road users to our count

sorry to get off topic, now to get back on - i have not had any experience with gps units, but my na fairlane and 121 speedos do seem very accurate, usually reading a little (2-5ks) lower than the speed guides. you would think that the better gps units should be fairly accurate though - some of them are pretty amazing with their directions and distances
if you are not sure though, maybe use the lower reading - it may cost a few extra seconds, but hopefully some decent dollars

flappist · 24-05-2009, 04:16 PM

I have done a lot of testing of this over many years.
I have a magellan GPS that I checked against Sydney radar at speeds up to over 400km/h and it was always spot on.
I also have my own KR10 mobile radar and have checked my tom tom and navman against it (navman up to 190km/h, tomtom only to 110km/h) and again they all agree.
Further to this I have checked my tom tom against a LIDAR that a friend of mine keeps in his pannier and again it is spot on.

So the short answer is YEP.

Paxton · 24-05-2009, 04:22 PM

My TomTom is pretty good.

I've been setting my Cruise Control to that, rather than the Speedo, and haven't yet had a fine or been pulled over. They are far more reliable than a mechanical/electric speedo.

itchy brother · 24-05-2009, 08:18 PM

Regarding the TomTom, why did they name it twice??

:

Ross-b · 24-05-2009, 11:43 PM

^ cos youd sound like a fag calling it a tom

"ohh yeh i unzipped it and grabbed my tom. touched the right spots and off we went"

yeh or something like that

dads 4 year old tomtom was spot on with a dyno speed check i did in my old car
ie when on the dyno i got all the road speeds compared to speedo readout on paper and tried them out on the road with the tomtom

fordfalconfan · 24-05-2009, 11:48 PM

Quote:

Originally Posted by outside

would you trust the speed reading on a GPS?
are they right? one would think so but how do you really know, short of getting yourself booked for speeding.

my mums Garmin nuvi navigator GPS is accurate we went through a speed check thing outside Melbourne and it was right.

Geez Louise · 25-05-2009, 12:23 AM

We use our Navman in the coupe. We test it through the speed checks too and it seems spot on. The only issue we seem to have with it is it gives wrong directions all the time like Turn left on the middle of the Westgate bridge.

Maybe it thinks our car is a submarine??

vztrt · 25-05-2009, 12:38 AM

GPS are accurate (can locate where you are within 30cm).
When they were originally released they were purposely made less accurate so you had military and commercial levels. This has been taken away. So you can trust them for speed readings.

Funnily enough I tested one against the trip computer avg speed (reset the avg speed and saw the current speed reading of the car) and it was within 1km/h. So something to keep in mind.

FPV GT40 · 25-05-2009, 09:39 AM

I have a mate thats been in Highway patrol for over 10 years, and he has tested the GPS navigators extensively, and they are spot on in the speed reading down to 1Km/hr.

He recommends people use the sat nav speed reading over their car one, as at different speeds the car speedo can be out to varying degrees. (Your speedo being out is no excuse or defence against a speeding ticket, as it is your responsibility to ensure your car is working correctly)

ie it might be out by 3 km/hr at 40Km/hr, while it might be 15km/hr out at 110km/hr.

If you have an older car (even a new one) check you speedo with a gps at all road speeds so you know its right, or how much its out by.

My FPV reads spot on at all speeds compared to the GPS, so its a very accurate speedo that I can trust at this stage.

Ross-b · 25-05-2009, 11:51 AM

Quote:

Originally Posted by FPV GT40

I have a mate thats been in Highway patrol for over 10 years, and he has tested the GPS navigators extensively, and they are spot on in the speed reading down to 1Km/hr.

He recommends people use the sat nav speed reading over their car one, as at different speeds the car speedo can be out to varying degrees. (Your speedo being out is no excuse or defence against a speeding ticket, as it is your responsibility to ensure your car is working correctly)

ie it might be out by 3 km/hr at 40Km/hr, while it might be 15km/hr out at 110km/hr.

If you have an older car (even a new one) check you speedo with a gps at all road speeds so you know its right, or how much its out by.

My FPV reads spot on at all speeds compared to the GPS, so its a very accurate speedo that I can trust at this stage.

there was a clause in the nsw sdro guidlines to get your fine reviewed if you had proof that the car speedo was out by more then 10% (as long as you werent speeding by more then 10%) they got rid of this halfway through reviewing my case though :|

vztrt · 25-05-2009, 03:50 PM

GPS's may lose their accuracy.

http://www.drive.com.au/Editorial/Ar...rticleID=63057

Darkr · 25-05-2009, 04:15 PM

Quote:

Originally Posted by vztrt

GPS's may lose their accuracy.

http://www.drive.com.au/Editorial/Ar...rticleID=63057

Psh, I often have a fix from 8 sat's.
Only 13/31 are past their design lifetime, I'm sure there will still be enough to have a fix on the required three.

vztrt · 25-05-2009, 04:23 PM

Quote:

Originally Posted by Darkr

Psh, I often have a fix from 8 sat's.
Only 13/31 are past their design lifetime, I'm sure there will still be enough to have a fix on the required three.

You need 4 sats.