Ian and I are hoping to run an autox this weekend in Detroit (saturday in livonia) with the Holey Spirit .
We have the track addict app, but have never used it with a gps extender. We're interested in trying it out to see if it is worth the $80 or so bucks to buy one ourselves. Here's a list of the extenders that work with the app:
http://racerender.com/TrackAddict/docs/Interop.html
Anyone have one we could borrow for the weekend? Maybe someone is already coming to the event with one? I'll happily buy beverages of choice.
Someone in Detroit might be best, but I could pick one up between Chicago and Detroit if anyone has one they are willing to lend.
That's a very unusual thing to have these days, I haven't seen one since phones started coming with built-in GPS receivers. I have one I haven't used in years but it's from the pre-ubiquitous-onboard-GPS days, and of course I'm nowhere near Chicago or Detroit.
I’m in the area, but have no such device to offer... 
GameboyRMH said:
That's a very unusual thing to have these days, I haven't seen one since phones started coming with built-in GPS receivers. I have one I haven't used in years but it's from the pre-ubiquitous-onboard-GPS days, and of course I'm nowhere near Chicago or Detroit.
Really? My current understanding is that the built in phone gps receivers have sampling rate issues for good data collection. (ie 1 hz or worse). You need an add on like this so that the app can get the 10 hz resolution so that it can be MUCH more accurate. I think the apps all use accelerometers in the phone to help interpolate position in-between gps 'hits', but small errors in acceleration become large errors in position quickly. Which is why the data becomes much more accurate if you can update position 10 times a second vs 1 time per second.
Anywhere we can go to check the specs of a phone gps receiver? I'm sure my phone is bad since I have a cheap phone but Ian might have a good one.
You're right that the built-in phone GPS receivers generally aren't very fast or accurate (better than 1Hz is extremely rare), but high-speed GPS is a niche technology and the built-in receivers are good enough for most uses.
I can't find any app to test the GPS refresh rate
At a code level, you'd basically have to find it by brute force, testing faster and faster sample rates until you stop getting unique data with every sample, at which point you've exceeded the maximum frequency:
https://stackoverflow.com/questions/17827142/getting-the-highest-gps-update-rate-from-the-gps-hardware-in-my-android
I can’t work it out for this weekend as I’m just out of surgery for a total shoulder replacement this morning, but I’d be willing to ship you my Dual XGPS160 for another weekend.
Not going to be driving anytime soon!
Karacticus said:
I can’t work it out for this weekend as I’m just out of surgery for a total shoulder replacement this morning, but I’d be willing to ship you my Dual XGPS160 for another weekend.
Not going to be driving anytime soon!
dang! I hope everything went well!
How do you like the xgps160? do you use it with android or ios?
For autocross, you would need the faster GPS due to the smaller size of the course and the faster direction changes.
For track days and the like, it isn't as badly needed and I didn't use one on my phone to collect reasonable data while at a track day.
Ultimately, it really depends on the device and OS you have.
In reply to Robbie :
I’ve found it to be a solid 10 Hz unit. I use it with iOS and Harry’s timer. Good battery life on it too for a track weekend.
Robbie, I've got a XGPS150 that you could borrow. I'm out west of Chicago though so it would be a bit of a drive for you. I'm unavailable to come meet you anywhere due to having work commitments tomorrow (day & night) through Friday night.
If you're interested in driving out this way, I work in Sycamore and live in Genoa.
Edit: I might be able to send it with a co-worker that lives in Plainfield for pick up on Friday night. This would save you a lot of the drive.
I'm not in your area but I did purchase a BT-Q818XT for just this reason and so far have used it with track addict at our winter rallycross. It seemed to work well and pair easily with my android phone as soon as everything was powered up. I haven't had a chance to try it with Harry's or Race Chrono but hopefully I will soon. So far, so good.
Adam
In reply to FooBag :
That's a really solid offer man, thanks!
I think however that I'm just going to bite the bullet and buy one. Resale on eBay seems strong so even if we don't like it I think the risk is low. Amazon prime has one day shipping on the xgps160, and I like that it can work for both Android and iOS
Just a visual illustration of the difference between 5 Hz and 10.
