MJM

I know, I know silly question because the body is fiberglass (sheet molded composite, whatever). I was just wondering if there are any areas (maybe trunk lid?) where you could mount a magnetic antenna to the car.

If anyone has found a spot that has metal under it (maybe by a hinge or something) or they have been able to put a piece of metal somewhere to make the magnet stick, I would appreciate it.

I am trying to find a way to mount a GPS antenna that connects to a data acquisition unit for track days.

http://www.race-technology.com/WebPa.../DL90Home.html

Thanks in advance,

Matt

ghoffman

Matt,
It is not a silly question, but there is no real place to do that. You would be better off using double sticky foam. You can get the goo off later with WD-40, without hurting the paint.
Another idea: You could make a mount that would mount inside the car, under the rear glass, since the car is transparent to the RF GPS signal.
I am VERY interested on how the unit works. Please let us know what you think of it.
Gary


[Modified by ghoffman, 9:21 PM 8/11/2002]

MJM

Thanks Gary,

I tried a few different locations and found that if I put the GPS antenna all the way forward on the dash, it had enough of a view of the sky to get line of sight with enough satellites to achieve a lock.

So I used velcro to mount the antenna and just went for a test drive around San Diego. Everything checked out OK and I downloaded the run to my laptop with the included software and have been messing around with it since then.

The software is very trick. It draws a track map and you can insert markers to get sector times. I don't know of any other way to get sector times other than a full blown telemetry setup. Within 1 minute of using the software for the first time I had a map showing me starting at my house and driving a loop around Mission Bay. You press play and it shows a dot going down the loop with G-force vectors during the playback.

You can then make bar charts or spreadsheets showing your sector times, average g, peak g, speed, or whatever you want for your run session.

The data logger unit has internal 2-axis accelerometers and is a little larger than a deck of cards. The GPS antenna is the size of a computer mouse. It runs off of 12 volt so you can use the cigarette adapter or hardwire it to a switched and fused circuit. It also has the ability to add extra sensors (wheel speed, steering angle, etc)

The unit required absolutely no calibration (other than mounting it flat, you do this by real-timing the data to a laptop and watching the angle readings until you have zeroed out both axis) and it self zeroes the accelerometers every time you power up.

I will be going to California Speedway this weekend and will have a full report afterwards. Hopefully I can post a file of a lap so people can download it. The website has a shareware version of the software so you could play around with everything using the lap from my car.

So far I am very impressed with this little unit

http://www.race-technology.com/WebPa.../DL90Home.html

here is the link to the guy I bought it from
http://www.cb-racing.com/

Matt

Dreamin

Matt, one thing I've wondered about this unit... will it work without having a laptop in the car while on track. Meaning can I use the laptop and set everything up in the pits, but then remove the laptop before I get on track? And have it save everything in it's memory? If so, how would it know where start/finish is (or any point for lap times), etc.

MJM

Yes.

The software draws a map after you download the session. You insert markers at the start finish and anywhere else on the circuit and the software calculates your lap times and sector times for every lap along with anything else you want (avg speed, max speed, avg g force, max g force, etc)

The data logger stores everything in memory. You DO NOT need to have the laptop in the car. The only thing in the car is the data logger and the GPS antenna.

You push a button to start the recording and then push the button at the end of your session to end. Then connect the laptop and using the software you download the session and save it to your hard drive.

After that you do everything on your laptop.

Matt

Mike Schriber

That is very cool.

How much were you able to buy it for here in the U.S.?

Thanks!

Mike :flag

ghoffman

Matt,
After you use it this weekend, how about a quasi product review (please!!!)?
What did you use for the wheel speed sensor? Where and how did you mount it? Where did you pick up the RPM signal on your C5?

MJM

I got the whole thing (data logger, GPS, software, USB cable, power cord, cool metal case) for $700.

A little steep but if you compare cost, ease of use, and capabilities to the other options (hotlap, full on data acquisition setups, army of engineers with stopwatches) I think you get a great deal.

The only other system that has gotten my attention is the one that taps OBDII and puts the info up on your in car camera. To me, the drawback of that system is its reliance on a camera to record the telemetry. This means you would have to watch your tape and write down info to compare between sessions. You would not be able make charts and graphs either. Although having in car camera footage with telemetry would look cool.

I will have the system at California speedway this weekend (BMW club) and hopefully at Willow Springs (TCRA) the weekend after if anyone wants to check it out.

Matt

MJM

I'm definitely going to help spread the knowledge, its the least I can do since I learn everything here anyway.

I do not yet have any extra sensors. That will come later. The included RPM sensor is apparently for use with vehicles with coil ignition so I am reseaching that one. Right now I have GPS position data , GPS speed data, accelerations in longitudinal and lateral axis ( down to 0.01 G accuracy), and GPS time. When the GPS and accelerometers work together the system has a 7 foot Circular Error Probability. That is very good, trust me.

I mounted the GPS antenna on the dash all the way forward against the glass. Small pieces of velcro hold it down. The upward view is wide enough to get satellite coverage. I mounted the data logger (a little bigger than a Valentine 1 radar detector) in the same fashion on the flat spot in the middle of the dash. This arrangement is actually rather stealthy if you use black velcro and remove the unit (obviously) when not using it. The logger needs to be mounted as flat as possible to avoid errors in the accelerometers. Pictures will follow.

Matt

Dreamin

Hmmm... I'm thinkin Group Buy :yesnod:

MJM

The guy I bought it from is a racer himself

http://www.cb-racing.com/

Shoot him an email and maybe he'll deal.

Matt

Dreamin

...will do... after your reviews this weekend and next!

ghoffman

Well Matt, how did it go? How was the data logger?