GPS speed measuring

[tamiyarcguy]

I have seen a garmin wrist sized GPS locator that I am debating buying to get accurated speeds from my rc's, I know there are cheaper ways of doing this like the venom system and even a stopwatch n such but to be able to track this with my computer and have a printout and digital map of where i drove it. Link

http://www.thegpsstore.com/detail_GA00329.asp

Im not plugging the website just where I found the best info and pics for the post.

Any worries or probs yall see with this...

I wouldnt think it weighed that much and should strap or mount to just bout anything (waterproof 1m for 30 min).

[WillyChang]

Have heard someone using the older/larger Garmin GPS to track his TA04, and it works great. Only drawback is you can't read it until the car is stopped. []

Venom thingy is only as accurate as your calibration. I wouldn't trust it for anything scientific.

Some of us here use K-band radar for instantaneous speed readings. These things read without stopping the car. [8D]

[bholio]

The one you referenced doesn't mention that it records top speed or is connectable to a computer. These are both features I'd look for in a GPS. However, the size is sure nice on the one you linked to.

[WillyChang]

Also the amt of "memory" it has.

One early machine I had a play with... it didn't have much storage. It'll track you fine, but when the RAM ran out the start of your trail started disappearing.

Talk about a modern "Hansel & Gretel" fairy tale! []

[tamiyarcguy]

Ive been fighting a bigger one because of the weight and I am going to let my family use it for kayak'n down the waterways.

[GPZ1000RX]

I use a GPS based speed camera locator and as I understand it the position updates itself every 15 metres and my locator uses an average of X readings to keep track of your speed. I'd say there is a definate question as to whether an RC car goes fast enough for long enough to allow a reliable or even any reading of speed to be taken.

[Wireless]

GPS isn't suited to r/c use unfortunately. I expect something like the Venom Speed Meter to perhaps be more accurate. The problem with GPS is that it's only accurate to around 5m. There are additional services GPS can draw on to improve accuracy (augmentation services). There is DGPS (Differential GPS) which uses ground stations to improve accuracy down to 1m. This is a GBAS (Ground Based Augmentation System). Then there is WAAS (USA) and EGNOS (Europe) which are additional satellite services that improve accuracy to better than 1m. These are calles SBAS (Space Based Augemntation Systems).

Now, GPS without augmentation is not accurate enough to use on r/c. The augmentation systems, although great for hill-walkers and such are useless for anything that moves faster than walking pace because the speed and direction cannot be updated quickly. This means you get the accuracy for r/c but it's useless because as soon as you turn a corner, the GPS only catches up a few seconds later.

These things combine to make GPS a no-go right now I'm afraid. Having said this, I am sure things will get better...!

Roop

[WillyChang]

Venom speed thingy needs to be calibrated manually, bit like a bike computer. Easy to get this estimation wrong.

It only reads revolutions of whatever you've glued the sensor magnet to; it cannot adjust for ballooning of tyres at speed.

Then... you can't read it offboard without stopping the car! [|)]

[Wireless]

That makes perfect sence Willy. Never used one of the Venom Speed Meters. Probably good fun for a club racer gadget but not accurate enough for pro racing I guess...? Balooning will certainly be an issue as will things like wheelspin. My TT-01 is in a permanent 4 wheel drift at high speed and on a lap probably adds 10% to the distance travelled...!!! I am a **** driver though...!!!

Roop

quote:

Originally posted by WillyChang

Venom speed thingy needs to be calibrated manually, bit like a bike computer. Easy to get this estimation wrong.

It only reads revolutions of whatever you've glued the sensor magnet to; it cannot adjust for ballooning of tyres at speed.

Then... you can't read it offboard without stopping the car! [|)]

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[tamiyarcguy]

Wireless Ill second the **** type of driver for myself I can barely hold a straight line and let a lone race without tanking into a wall...

My company Solved my speed problem, one of our tests on garage doors in the US uses a 2 by 4 peice of lumber shot, yes shot, at a door/panel/window 3 times within a 6 in. target to test the structural strength of a door... to check that the velocity of the board is to the standard the company purchased a radar gun for baseballs. Its good at picking up smal objects baseballs softballs and OOHHHOOOHHH rc cars. It isnt what they needed so its just gonna sit around and just might make it home one weekend soon.

I have a HPI RS4 2 heavily modified racer that I wanna get a speed check on and I think it should top 50 mph and hopefully with a little better tune 55 to 60 MPH.

Anyway thanks for the input and helping me hold off until this accidental over run of useage on the radar gun

Guy