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Author Topic: GPS Datalogging and Analysis  (Read 7497 times)
stanrc
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« on: July 13, 2014, 03:49:11 PM »

I've attended a few VMSC events as well as a few other DC area events this year and every time someone asks "Whats taped to your trunk?" So I thought I'd do a quick write up of my setup to include the parts I have and the end results.

This is the bluetooth GPS I use, it polls at 10 hz (most cell phones are only 1 hz) so it is more precise for events like this. Its very simple to use, just turn it on and pair it with your phone.

http://www.amazon.com/BT-Q818XT-Qstarz-10Hz-Bluetooth-Receiver/dp/B003YCZINA/ref=sr_sp-atf_title_1_1?ie=UTF8&qid=1405290192&sr=8-1&keywords=qstarz+bt+gps

For software, I use RaceChrono on my android phone.  HarrysLapTimer is another popular android one that is supposed to be very similar but I haven't used it.

For an AutoX event you have to tell it where the Start and Finish line are, I do this during the course walk. Then once my heat is ready to start, I start the session (recording data) and thats it.  Based on the start and finish points it will keep track of your lap times, although its usually not 100% exact, it may be off by a 1/10 or so. 

Now comes the fun part, data analysis. For this I use RaceChrono on my Windows PC.  Its a ported version of the mobile app so its a little clunky to use on a computer, but it gets the job done once you figure it out. Once I've moved the data over to my computer I have to re-tell it where the start/finish points are and I add in a few split points to keep track of various sections of the course. This gives me something like this:



And then I can compare each laps time through the sections:



As well as compare one lap to another, I usually have a more experienced co-driver so its very helpful to be able to compare my lines to his.
This screenshot is just two of my own laps so the lines are pretty similar. I've learned a lot from being able to see exactly how much a mistake costs me or when trying a new line pays off.



And lastly I can add this data to GoPro footage and get a nice overlay with the track, G-forces, MPH and almost any other data you want.  I didn't have the GoPro today, but here is a past event.  I used RaceRender to merge the data and video and sync it.

https://www.youtube.com/watch?v=og4yakbNgA0

I hope this was useful, please let me know if you have any questions about my setup.
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whiteryder
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« Reply #1 on: July 13, 2014, 04:43:40 PM »


That's really cool!  

I have the Qstarz  Q1000eX 10Hz GPS lap timer, I think it's similar to yours but it has a data logger.  So I don't really do anything with mine at the race besides turn it on.  When I get home I download the data into QRacing software to set start/finish beacons etc.  

I've figured out how to combine it with video using DashWare (Qstarz has a discount).
Have to do a little guesswork to get them synced, but it's not hard to get it close enough.

Now if only I had a run worth sharing!   lol

« Last Edit: July 13, 2014, 05:11:48 PM by whiteryder » Logged

2002 Honda Passport
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1998 BMW M3
stanrc
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« Reply #2 on: July 13, 2014, 05:58:47 PM »

Thanks, I haven't heard of the Qracing program but it looks neat.  I'll have to try it out.
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bobzdar
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« Reply #3 on: July 14, 2014, 04:30:35 AM »

Very cool, I've been using the trackmaster app which I like because it gives satellite imagery overlay, but I need to get one of those external gps units for it to work for an autox.
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Pete
stanrc
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« Reply #4 on: July 14, 2014, 04:52:55 AM »

When you use RaceChrono on the phone it adds the sat imagery, its just harder to view the data on a 4.5" screen so I usually move it to my desktop. 
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whiteryder
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« Reply #5 on: July 14, 2014, 05:09:35 AM »


Actually I do have a question.  My unit has a feature where it can automatically start logging when you start moving, and stop when you stop (based on detecting vibration).  This sounds useful for autox so it doesn't log the time you spend in grid, but I've never trusted it to work so I always have it disabled.  Does yours have this feature, and do you use it?
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2005 Porsche C2
1998 BMW M3
stanrc
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« Reply #6 on: July 14, 2014, 05:20:25 AM »

I believe the GPS is recording anytime its on, but when you start the app it knows to start collecting and saving data.

So I guess it doesn't really have an auto-start/stop, but based on your pre-set start and finish points it will make those "laps" and hides the rest of the data. So all the data in the grid will still be there, just not shown to you. I just tell it to start logging once my heat is about to start and let it keep running throughout.  The file size after is usually about 1-2 mb.
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whiteryder
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« Reply #7 on: July 14, 2014, 05:21:51 AM »

BTW our forum software is pretty primitive, doesn't size images to your browser.  Tongue

Looks like width is only 720 pixels before you get the horizontal scroll.
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2002 Honda Passport
2005 Porsche C2
1998 BMW M3
stanrc
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« Reply #8 on: July 14, 2014, 10:18:43 AM »

OK I'll resize the images. I wasn't sure if it was just me.
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whiteryder
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« Reply #9 on: July 23, 2014, 04:58:19 PM »


DashWare just finished a customer video contest.  Here are some great examples
of what can be done with the software, given sufficient time and motivation.

http://www.dashware.net/dashware-video-contest-winner-announced/
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2002 Honda Passport
2005 Porsche C2
1998 BMW M3
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