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-   -   I don't believe your GPS'd speeds! (https://www.rc-monster.com/forum/showthread.php?t=17347)

BrianG 12.17.2008 03:16 PM

I don't believe your GPS'd speeds!
 
Some people use a GPS to measure the speed of their R/C car. But the other day, I was driving around and my GPS "hiccuped" and showed an impossible reading of 177mph. I drive a Mazda3 S (hatch) with a computer limited top speed of 118mph (verified). And I am the only one who uses this GPS.

The only software manipulation done was to crop and resize...

http://scriptasylum.com/forumpics/gps_bad.jpg

Tempted 12.17.2008 03:27 PM

Haha. Thats a one off. I haven't seen that before. Maybe you time warped a couple feet.

jayjay283 12.17.2008 03:53 PM

Not to mention your great runtime ! 177 mph for 45 minutes, you have some sick lipos

suicideneil 12.17.2008 04:08 PM

GPS am not work... http://www.beatyourtruck.com/forum/i...on_scratch.gif

DickyT 12.17.2008 04:16 PM

fastest Mazda 3 on the planet!

wallot 12.17.2008 04:19 PM

are u sure it's miles? maybe it's meters :)
slowest mazda 3 on the planet :)

jhautz 12.17.2008 04:39 PM

Did someone throw the GPS unit from the back seat to the front seat while you were driving at that 118mph? lol

kulangflow 12.17.2008 04:44 PM

That's pretty funny. While on an airplane, my brother turned on his gps and hit 377 mph.

TDC57 12.17.2008 04:58 PM

I tried that excuse with a cop / judge once! :intello: (I think I was 19 years old), I was in a VW bug and he clocked me at 95, :gasp:

I was trying to tell / explain the judge that my car doesn’t go that fast down hill with a 20mph wind behind it!..:rofl: he laughed and fined me $365.00 and cost me two points :diablo:

Dam GPS units!...:wink:

BrianG 12.17.2008 04:59 PM

Yes, it's mph. If it was using imperial units, it would be kph. :wink:

I don't know what happened either. One minute the top speed was ~115 (I just HAD to test that 118 mph top speed :smile:), and the next it was at 177. It always stays in its little holder so no I didn't toss it anywhere while going 118. Futhermore, I'd have to throw it around 50mph forwards and as I'm already in the front seat, it would be slightly bad for its health (not to mention whatever it hit). :smile:

I'm sure for the most part, GPS is accurate, but I thought this was interesting. Makes you wonder now if all measurements are totally accurate. Hmmm.

Arct1k 12.17.2008 05:58 PM

GPS speed just works on interpolation of your position at different time intervals.

If you had a false GPS read i.e. put you several 100 yards ahead the math gives you an off MPH reading.

What's_nitro? 12.17.2008 07:11 PM

^ Maybe it had to switch over to another satellite right then? That could account for the hiccup.(?)

That, or you were doing some automotive skydiving......

Arct1k 12.17.2008 07:15 PM

GPS works by triangulation normally of 6 or more sat's so shouldn't be an issue. But I've occasionaly had it sometimes when driving down the highway and suddenly and temporarily think I'm on the parrallel rd.

BL_RV0 12.17.2008 07:17 PM

Yeah, just a random hiccup.

MTBikerTim 12.17.2008 07:19 PM

Having played with some data logging gps systems recently I have to say that this isn't that uncommon. The gps uses a lot of clever maths to smooth out readings but sometimes it doesn't always work. If you consistently get the same speed doing speed runs with an RC car then it is most likely accurate though.


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