joeg
Full Access Member
What's more accurate ? (would guess the speedo) my Garmin shows approx. 3-5 miles slower than speedo.............
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It doesn't look like you have a lift from your signature so I would assume your Speedo is more accurate. You also have to remember that the Garmin is pulling satellite communications which could slightly off set the actual speeds based on any delays in communication.
What's more accurate ? (would guess the speedo) my Garmin shows approx. 3-5 miles slower than speedo.............
Eddo, remember the refresh rate of his GPS receiver. I am not sure how well it does, but if it is one of those slow refreshing GPS receivers, it may not be accurate to the second.However if his GPS is always faster or always slower, than there could be a problem.
Eddo, remember the refresh rate of his GPS receiver. I am not sure how well it does, but if it is one of those slow refreshing GPS receivers, it may not be accurate to the second.However if his GPS is always faster or always slower, than there could be a problem.
I have to check what my GPS update rate is. I am using Pocket PC with Mapopolis, which has pilot data, and it has been very accurate, to the mph. It is a bit off the right, so it thinks I am on the service road sometimes...
GPS is way more accurate. Just a standard receiver should be accurate to about better than .5 mph. Speedometer are notoriously inaccurate, even on new vehicle with a stock setup. Speed is actually calculate off doppler shift of the GPS signal, not change in position.
Chances are that the map is off of position, especially if you are always shown to one side of the road. The Garmin stuff is awesome, & the newer ones that use WAAS can be accurate within a few feet. The GPS receives a time code signal from the satellites, & uses the difference between those time codes to triangulate your position. It is far more accurate than the mechanical speedometers which have numerous ways to be maladjusted.
Yeah, It's a weird thing. The GPS can pin point your location with nearly 0 error it terms of lattitude & longitude, & that is all that is needed for speed & distance calculations. When the maps are added, they are like a wrapping paper on a package, prone to slight misplacement. The different programs you are running are probably not quite in synch.Maybe, I am always to the left of my heads up. No matter which direction I am going, since it is set up to rotate according to my direction.
I am using WAAS receiver, it is Haicom MMF. The maps are NAVTEQ, although a bit old.
I wish google made their maps available off-line for GPS usage on Pocket PC. Those maps have great features.