So I was looking at things on one of my GPS and happened to see this. I am not sure I have been in a car (or anything for that matter) that can do 168 MPH for a very long time.
Evidently my GPS does not agree.
I can see it now. Officer Look at my GPS there is not way I was over the speed limit see my max speed is. .. . . . .. .. . 
I did an indicated 160 on my FZR600, it was probably wildly optimistic and was more like 130. But that still was booking it.
A GPS confirmed 168 would be pretty damn quick.
did you bring it on a recent flight with you?
You can trick those things by swinging them around or moving them really quick. 
168 seems low for a flight.
In reply to sachilles: Depends on what you're flying. In a 172 or most choppers, you're moving along pretty well!
Are you sure it's reading out in MPH?
168 meters an hour is quite slow
And that's why you cannot rely only on GPS to tell you your speed.
I ran 6 miles (on foot) recently @ around 50-80mph recently... according to my GPS.
I've wondered about the deliberate fuzzing of the position on those things. You know the feds used to insert a random-like noise signal to the sats so that you could never tell where you were closer than about 1K ft or so. So "our enemies" would not be able to use our GPS for their targeting, they said. Although why anyone would use their enemy's GPS for targeting must only make sense in government circles. Then everyone started broadcasting the correction and hand held GPS' could receive both signals and tell where you were enough to navigate a channel with. So the feds stopped the random-like noise signal and let the things run to full accuracy, with the warning that they could fuzz it out on you again anytime they wanted and with no warning.
So, I wonder if your 168MPH stint was a fuzzing/unfuzzing test or something? When that signal shifts, it would put you somewhere else instantly, and the GPS could do teh maths and say you had to be going 168 to get there since the last fix a few seconds ago. Just a theory.
I have another theory: If you're someone the feds don't like, put a GPS on your desk. Note where it says your desk is. When your desk suddenly moves a hundred yards, the E36 M3 is about to hit the fan.
Here's a pic of my GPS.
I will double check the MPH but I am sure it is set for that.
Dr. Hess wrote: I've wondered about the deliberate fuzzing of the position on those things. You know the feds used to insert a random-like noise signal to the sats so that you could never tell where you were closer than about 1K ft or so. So "our enemies" would not be able to use our GPS for their targeting, they said. Although why anyone would use their enemy's GPS for targeting must only make sense in government circles. Then everyone started broadcasting the correction and hand held GPS' could receive both signals and tell where you were enough to navigate a channel with. So the feds stopped the random-like noise signal and let the things run to full accuracy, with the warning that they could fuzz it out on you again anytime they wanted and with no warning.
It's called "Selective Availability" and the idea was to stop the Soviet Union from using a US-built system to guide weapons (smart bombs, cruise missiles, nukes, etc), while preserving the ability of the US military to do precisely that. GPS was pretty high-tech at the time, and there was a good case to be made that the Soviets weren't capable of building their own. It was also quite expensive to launch the 24 satellites required. Remember that while GPS went operational in 1993, after the fall of the USSR, they started working on it in the 1970s when the cold war was in full swing.
Differential GPS let you solve a lot of the SA fuzzing, but it wasn't a universal solution because you needed to receive a differential signal from a transmitter fairly close to where you were. I suspect half the reason for turning off SA was that by doing that you removed a lot of incentive to further roll out D-GPS, thus making the ability to turn SA back on later more useful. :) I've also read that, during the later invasion of Iraq, they didn't turn SA back on because the military had started buying civilian-grade GPS receivers and so they would have been significantly affected as well.
Another limit on the system is that apparently all of the commercially available chipsets are designed so that if the speed is too high (like over mach 3 or something) then it stops putting out a position, thus preventing them from being used to guide ICBMs.
My friend had a GPS mounted in his Viper a few years ago and had a similar thing happen to him. His said he hit 280 mph.
I've had mine do weird readings in downtown areas with tall buildings around.
Grtechguy, the signal was probably bouncing off those buildings and that was throwing the timing off.
When I was sailing in the 80's, there were 6 birds up, if I recall, and we only got a fix about every 6 hours. It would take a GPS receiver the size of a medium sized CRT TV set several hours to do teh maths and tell us were we were a few hours ago.
I think the Russians launched their own set of GPS sats so they would have something not dependent on the U.S. I think they open it up to everyone as well.
codrus wrote: Another limit on the system is that apparently all of the commercially available chipsets are designed so that if the speed is too high (like over mach 3 or something) then it stops putting out a position, thus preventing them from being used to guide ICBMs.
I believe there's a altitude limit as well, somewhere around 100k feet or something like that. I've read about colleges running into that with cheap research balloons.
The signal can bounce off buildings as others have pointed out, and make it look like you're going in the opposite direction that you actually are.
What probably happened here was that a speed measurement was taken with poor sat lock. Your location was probably flying around at high speed while you were picking up more satellite signals. I have an app on my phone that shows where you are regardless of signal quality, and when it's weak it usually shows me doing fast circles around my actual location.
I did around 1.5 miles in 13 seconds on my bicycle. Went out of range for a minute, always happens on that trail. Definitely signal bouncing.
mr2peak wrote: I did around 1.5 miles in 13 seconds on my bicycle.
Steep Hill!! 
codrus wrote: Another limit on the system is that apparently all of the commercially available chipsets are designed so that if the speed is too high (like over mach 3 or something) then it stops putting out a position, thus preventing them from being used to guide ICBMs.
So that's why my GPS quits working on my drive in to work.
You'll need to log in to post.
