mark kibort

It looks pretty interesting as it will map the track and give your stats after a lap, or several laps. I dont know its limits, but the example on the app site looks interesting. I have "dynolicious, and havent been too impressed. Thats an app that would be better if they had a selectable HP reading speed range. (Like 60-100mph or something).

I guess for $20, what can you expect

mk

007DT

Is the program called G-Tech?

mark kibort

Sorry, got the name wrong.

Its called g-tac pro.

mk

IcemanG17

MK
I have dynolicious and "trackday"....I bought trackday because it has a GPS driven lap timer...I haven't tried it in the race car yet, since I don't have a mount for the iphone.....but the GPS lap timer does work..I tested it in some big parking lots at work! I've used dynolicious quite a bit too

007DT

Glad I just bought that trackmate

Weston

I have both G-Tac Pro and Log Box (datalogger made by the Dynolicous people) on my iPhone 3G. I haven't gotten to play with them too much, but here's what I've found so far...

G-Tac Pro
- Pretty simple to use and it will let you replay your path and G's afterward
- Accelerometer samples at 30Hz
- GPS samples whenever it can get a clear signal (best I've seen is 2Hz, but other times there are gaps)
- Raw data can be e-mailed to you and it's two sections of CSV formatted data... one for accelerometer and one for GPS
- Unsure how long it can record for, as I've only used it for a few minutes at a time. There is no limit that I'm aware of.

Log Box
- This is really more of a recording app, with no replay ability on the phone itself
- Sample rate is 100 Hz by default, which only lets you record for 5 minutes. Take it down to 20Hz and you get 25 minutes. Next step below that is 1Hz, which gives 8 hours.
- GPS actual sample rate and accuracy seems to have same the issues as G-Tac Pro, since it's really mostly an iPhone hardware limitation
- Data is uploaded to their server (that's what it's doing when you're spending all that time waiting on it) and it e-mails you a link, then you can download it in a few different formats. Just like G-Tac Pro, it does not use accelerometer data to interpolate the GPS position and speed in the data export.


So... both of them could potentially be used as a cheap datalogger for the iPhone 3G, but the iPhone's GPS reception and precision are an issue, so it's certainly not a Traqmate or other real datalogger. The best I've seen with it sitting on the dashboard of my truck was 9 meter accuracy and a 2 Hz sample rate, but that was rare. It was usually more like 17 meter and 0-1 Hz. Neither app will use the accelerometer data to interpolate the GPS position or speed (G-Tac seems to do it for the replay on the phone, but not for the data it exports), and neither offer anything for doing lap times or segment times. They're both really begging for some desktop software to do both of those things and maybe some other stuff. I've been super busy getting ready for a race this weekend, but when I have some time, I'd like to take a shot at that myself...

I do think they have some potential, it's just hard for the typical user to make the most of them at this point in time, and at the very least they could be a cheap way to collect data for overlaying onto video (ie G-Force plot and track map/position). I've already done that for a short test run with G-Tac Pro and it looks decent except for where the GPS lost it's signal for a few seconds, but again I think software could be used to clean that issue up quite a bit.

As for this coming race weekend, I hope to run these apps side-by-side with my Traqmate and video...

webbie

Great review. Could you share how you combine G-Tac Pro with video?

mark kibort

Yes, good review! Let us know how it goes. Im also interested how to merge the data with video. but, just feed back on a few of the first laps of a race or qualifying would be great.

I got this information out of the dynolicous performance software. Its sears point, but who knows what turns these are. the only clue is the time stamp area.

Thanks

mk

FTS

I am thinking of trying this, anyone have experience with Rev? I particularly like that it can read ECU data rather than hardwiring sensors.
http://www.devtoaster.com/products/rev/index.html

Weston

I tried both G-Tac Pro and LogBox last weekend, along side my Traqmate. G-Tac is my clear preference of the two iPhone apps... it's simple to use, can replay the session on the phone, the data export is two simple CSV sections, and it doesn't let the phone lock when you have an unexpected 20 minute delay in grid. Unfortunately, both suffer from the iPhone's GPS reception issues. It seems that the center tunnel is a great place to mount an accelerometer, but not so great for a GPS antenna. Because of that, I was only able to compare accelerometer data this time. I hope to try this on the track again next month and will hopefully be able to collect GPS data then...

I've had people on multiple forums asking about this, so I put my G-Tac vs Traqmate comparison and video out there as HTML that I can link everyone to... http://www.rm944.com/weston/iPhone/G...%20090419.html


As for LogBox, it lacked sufficient GPS data as well (I mounted the iPhone in the same place for both apps), and it doesn't give me a clear time-stamp on the accelerometer samples, so I don't have anything put together for it right now. Basically, it was writing multiple samples with the exact same time values, and it didn't log at a steady 20Hz like I set it to, so that really leaves something to be desired. I would hope that future updates correct that...


I did the video overlay with RaceRender 0.95 by putting the accelerometer data into a CSV file (make sure the first line contains the column headings), and in cases where GPS was available I put that data into another CSV file, then overlaid them both over the same video. In the above example, it was the accelerometer section only. If you're comfortable tweaking CSV files and column headings, you could probably get it to work with TrackVision or DashWare as well, although they may not support more than one instance of logger data per video.

webbie

Thanks for the review.

Another data point, I tried the G-Tac today at Mosport, it cannot pick up the GPS signal.

morefun

I tried Trackday at Lime Rock this weekend but was disappointed that it was absolutely unable to generate a GPS fix. On the other hand, MotionX an app used for orientering etc., had no difficulty acquiring a (speedy) fix....

Coochas

Bump.

Anyone else having good/bad experiences with these iPhone lap timers?
BTW, can you leave the iPhone in your pocket or do you need to fasten it to the dash.

sjfehr

Anyone tried any PocketPC lap timers or g-force meters? I've tried two on my Omnia with mixed results.

waynesworld

I had good luck with Harry's LapTimer running on a Treo before installing a G2X. He has since created an iPhone version that is available on the AppStore. I have installed it and tried it off track and it seemed to work well. No affiliation. Link below.

http://web.me.com/hschlangmann/LapTi...iPhone%29.html

-Wayne