BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > E90/E92 M3 Technical Topics > Track / Autocross / Dragstrip / Driving Techniques
 
INDustry distribution
Post Reply
 
Thread Tools Search this Thread
      03-04-2011, 01:49 PM   #45
RickyBobby
Lieutenant
RickyBobby's Avatar
14
Rep
519
Posts

 
Drives: M3
Join Date: Mar 2008
Location: NorCal

iTrader: (2)

Quote:
Originally Posted by jml View Post
Here is what I am talking about, notice on the G2X (below) that the data is VERY much aligned. (All data from TWS in my E90)


On the traqmate (below), similar data, but out of alignment between laps (sat vs sunday). This is caused by drift, and was explained to me to be something that is "sometimes" normal by the tech support at traqmate. We tried different GPS loctions, different receivers, different main units. Same results. Pretty frustrating when you are used to the accuracy of the G2X unit, which was flawless IMO, except for the usability of the software.
The traqmate software has functionality to fix the sat drift. Did you ever try that? Seems like a shame if that's the only reason you got rid of yours.
I've only had my traqmate for one weekend so I don't have enough data yet to see any drift. Time will tell.
Appreciate 0
      03-04-2011, 02:47 PM   #46
lucid
Major General
lucid's Avatar
United_States
116
Rep
8,034
Posts

 
Drives: E30 M3; Expedition
Join Date: Apr 2007
Location: USA

iTrader: (0)

Quote:
Originally Posted by RickyBobby View Post
The traqmate software has functionality to fix the sat drift. Did you ever try that? Seems like a shame if that's the only reason you got rid of yours.
I've only had my traqmate for one weekend so I don't have enough data yet to see any drift. Time will tell.
Thanks for the info. If you have more track time within the next 2-3 weeks (my purchasing timeframe), please let us know if the drift issue is resolved.

Edit: Are you happy with the video integration (if you have video)?
__________________

Last edited by lucid; 03-04-2011 at 03:35 PM.
Appreciate 0
      03-06-2011, 12:34 PM   #47
MaxL
Captain
Canada
18
Rep
952
Posts

 
Drives: E90 M3, Cayenne T, 991 GT3
Join Date: Jun 2007
Location: Bay Area

iTrader: (0)

Quote:
Originally Posted by cchan View Post
The iPhone only samples GPS locations about 1x per second and the built-in antenna isn't the most accurate, so be aware of those limitations. Apps like Harry's give a good taste of data acquisition though, especially for the price. I have a G2X system, but if I was going the lowest cost route, that would be the one I would use.
There is a way to use external bluetooth GPS with 5Hz or even 10Hz update rate (real, not interpolated) on iPhone. My GPS datalogger has an option of working as an external blutooth GPS, so I am going to try it with the Harry's app for recording G-forces and overlaying lap map on the video (something my datalogger cannot do by itself). Will report back in April.
Appreciate 0
      03-28-2012, 08:47 AM   #48
dogbone
Second Lieutenant
dogbone's Avatar
4
Rep
281
Posts

 
Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (0)

Regarding external GPS sensors for iPhone, I bought the Emprum UltiMate GPS hardware device that attaches to the iPhone to work with Harry's Lap Timer Pro and it is very accurate. It has 5Hz refresh (5 times/second) and is usually tracking 9-11 satellites when on the track. It supports Differential GPS which means it not only tracks satellites in the sky, but also ground based stations which really increase the accuracy.

I just leave it inside the center console of my E90 M3 with the lid shut and it's fine in there. I have a GoPro and record all my laps and go back later and time them watching the video, and Harry's Lap Timer Pro and the Emprum are always spot on.

I have a friend in the aero-space industry who is working on the new GPS-based air traffic control system (ADSB), and I was asking him how much I could trust a device like an Emprum. He said when the device is in Differential GPS mode, that it's extremely accurate.

hehe a side note in all of this: Harry's Lap Timer and the Emprum work as a speed checker while driving down the road. My analog speedo is 6mph off, and my digital speed readout is 4mph off.....so if it shows 70mph on the iPhone screen, the digital display on the car shows I'm going 74 and the analog dial shows 76.....
Appreciate 0
      03-28-2012, 10:18 AM   #49
M3 Montreal
Colonel
30
Rep
2,188
Posts

 
Drives: 2012 M3 SG ,DCT & 2011 S4
Join Date: Oct 2008
Location: Montreal , Canada

iTrader: (0)

I also use Harrys Lap Timer with a TomTom cradle which was recommneded by the makers of the program. The cradle has a built in antenna to boost accuracy and it works great.
__________________
2012 E92-M3 Space Grey on Fox Red, DCT

2011 B8 S4 S-Tronic , Black on magma red
Appreciate 0
      03-28-2012, 10:38 AM   #50
dnvrdrvr
Captain Obvious
dnvrdrvr's Avatar
United_States
8
Rep
799
Posts

 
Drives: 2011 Carbon X5M
Join Date: Jul 2009
Location: Denver, CO

iTrader: (4)

Another option that I'm considering is Race Keeper. Went to an all-day data workshop last month and was impressed with what they offer. One thing he said that resonated had to do with satellite drift - it's a fact of GPS-based systems and they've programmed in algorithms to account for it. IIRC, you can load up to 4 cameras - the video feeds automatically sync with the data feeds. It's not a cheap system, but the integration they offer is pretty cool.
__________________
Just a girl and her 550 ponies...
www.mw3motorsports.com
Appreciate 0
      03-28-2012, 05:00 PM   #51
lutfy
Second Lieutenant
lutfy's Avatar
3
Rep
251
Posts

 
Drives: 2009 E90 M3 DCT, 2005 997 C2S
Join Date: Mar 2012
Location: Washington DC

iTrader: (1)

Surprised no one ever mentioned PerformanceBox by Race Logic (www.racelogic.co.uk). Car and Driver along with many tire companies and auto manufacturers use it. Have Performance Box and loved it! It seems to be the bees knees outside of the US.

Linky to one in my car. Great for predictive lapping and data analysis after:

http://vimeo.com/user3800046
Appreciate 0
      03-28-2012, 05:11 PM   #52
ThunderMoose
Captain
14
Rep
971
Posts

 
Drives: 2009 C2S and 2003 E46 M3
Join Date: Aug 2010
Location: League City, TX

iTrader: (0)

Probably late to party but the AIM Solo or SoloDL are very good GPS based timers.
Appreciate 0
      03-28-2012, 05:31 PM   #53
dogbone
Second Lieutenant
dogbone's Avatar
4
Rep
281
Posts

 
Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (0)

No doubt that VBox, Race Keeper, Solo and some others are very cool, but they do cost quite a bit of $$$. If you already have an iPhone, Harry's Lap Timer Pro is $19 and the Emprum is $90. Plus, the Emprum works with all location-based apps on the iPhone without any additional drivers or setup, making them much more accurate too. Sometimes I use the Emprum on my bicycle rides with the Strava app. That's very cool. (The Emprum does take longer to get a GPS fix initially then the internal iPhone GPS though.) Anyway, when you're still a noob like me, this is a cost effective way to have fun.
Appreciate 0
      03-29-2012, 10:28 PM   #54
kartracer12
Private
1
Rep
57
Posts

 
Drives: e90M3 White
Join Date: Mar 2009
Location: VA

iTrader: (0)

I demo the Race Keeper system and loved it. Video integration is built in and they have an iPhone timer display.
__________________
Stoptech ST-60/ST-40 BBK | Akrapovic Full Evolution | Dinan Intake | Dinan Pulley | Apex Wheels | BPM Sport Tune | Euro MDM | BMW Motorsport Carbon Spoiler
Appreciate 0
      03-29-2012, 10:30 PM   #55
1MOREMOD
2014 Track Days - 11|Ridge 1:52:24|Pacific 1:35:72
1MOREMOD's Avatar
United_States
173
Rep
12,998
Posts

 
Drives: Race car->
Join Date: Mar 2009
Location: check your mirrors

iTrader: (5)

Quote:
Originally Posted by ThunderMoose View Post
Probably late to party but the AIM Solo or SoloDL are very good GPS based timers.
i have works great for my purposes.
__________________

02 Tiag e46 M3|6MT|GC plates|MCS c.o.|GC bars|GC race control arms|GC bushings|BW eng. & tran. mounts|subframe kit|BW race shifter|BW Jaffster|Euro header|BW exhaust|K&N c.a.i.|Epic race tune|Rouge pulleys|Seibon CF hood|CSL bumper|ST-40|XR-2|SS lines|half cage|Recaro profi|Profi 2 harness|BMWpedals|BW studs|
Appreciate 0
      04-12-2012, 10:02 AM   #56
M3 Montreal
Colonel
30
Rep
2,188
Posts

 
Drives: 2012 M3 SG ,DCT & 2011 S4
Join Date: Oct 2008
Location: Montreal , Canada

iTrader: (0)

New update of Harry's LapTimer!

Many new updates including.... Continuous recording instead of every second lap!!
__________________
2012 E92-M3 Space Grey on Fox Red, DCT

2011 B8 S4 S-Tronic , Black on magma red
Appreciate 0
      06-26-2013, 09:30 AM   #57
richardg
Major
richardg's Avatar
34
Rep
1,331
Posts

 
Drives: e36M / e92M / e36 328i
Join Date: Jul 2006
Location: Bloomfield Hills Mi.

iTrader: (5)

I use ALapHD (unfortunately no longer supported but has everything) and trackmaster on Android. I pair that with an external bluetooth GPS antennae and OBDII reader.
Appreciate 0
      06-26-2013, 11:57 AM   #58
JonnyTrauma
Private
United_States
0
Rep
91
Posts

 
Drives: e92 m3 6mt
Join Date: May 2013
Location: Philadelphia

iTrader: (0)

Lap timers on android/iphone are only accurate within 1 second. The GPS receivers in these devices have a 1 Hz refresh rate which means it grabs your location once every second. This is only accurate to within ~30 feet assuming you have a strong signal. So yes, this will give you an idea within about 1.3 seconds of accuracy what your lap time is.

You can get an external 10 Hz GPS receiver than will increase the accuracy to 1/10th of a second. That will cost you about $100.

Dedicated GPS laptimers from AIM, Qstarz and Starlane are solid. I use the Qstarz--it is not user friendly but once you figure it out, it works well, is accurate and has great battery life. I've heard battery life is not ideal with the app based solutions so that is something to consider as well.
Appreciate 0
      06-26-2013, 03:29 PM   #59
dan avoN7
Enlisted Member
1
Rep
42
Posts

 
Drives: 04 M3 Alpine White
Join Date: Jul 2011
Location: Danville, CA

iTrader: (0)

Quote:
Originally Posted by JonnyTrauma View Post
Lap timers on android/iphone are only accurate within 1 second. The GPS receivers in these devices have a 1 Hz refresh rate which means it grabs your location once every second. This is only accurate to within ~30 feet assuming you have a strong signal. So yes, this will give you an idea within about 1.3 seconds of accuracy what your lap time is.
Not entirely true for all lap timers.. Harry's Laptimer for example is very accurate for overall lap times even when using the internal GPS @ 1hz. Harry's LapTimer does sophisticated interpolation to calculate the actual point and time the start / finish line was passed. It calculates the trigger‘s perpendicular projection to the virtual line between the GPS fix before and the GPS fix after the trigger. Having calculated this point, the time this point was passed is calculated by linear interpolation from the speed at the fix before, the speed at the fix after, and the distance between these two points. As long as the speed development is near linear, this interpolation yields accuracy beyond 0.01 seconds. This is the reason, why receivers with 1 Hz update rate are fully sufficient for timing and equal accuracy of other technics.

I put my friends VBOX (GPS @ 10hz) in my car for a session at Laguna Seca awhile back and the times were within 0.01 seconds of the times reported with Harry's Laptimer using the internal GPS @ 1hz. I have since added an external GPS @ 5hz to get more accurate readings in turns but for overall lap times the internal GPS works fine
Appreciate 0
      06-26-2013, 04:01 PM   #60
Longboarder
Brigadier General
66
Rep
3,809
Posts

 
Drives: 2013 e92 M3
Join Date: Dec 2006
Location: Monarch Beach

iTrader: (1)

Garage List
2011 997.2 Turbo S  [4.71]
2013 e92 M3  [4.55]
2013 BMW X5  [0.00]
Quote:
Originally Posted by lutfy View Post
Surprised no one ever mentioned PerformanceBox by Race Logic (www.racelogic.co.uk). Car and Driver along with many tire companies and auto manufacturers use it. Have Performance Box and loved it! It seems to be the bees knees outside of the US.

Linky to one in my car. Great for predictive lapping and data analysis after:

http://vimeo.com/user3800046
someone mentioned it already on page 1 (back in 2009).

Yes it's fantastic for getting better (particularly for a novice like me) as it provides an incredible amount of data for analyzing, but it's too expensive for someone just wanting a lap timer.
__________________
Daily: 2013 e92 M3 DCT / ESS VT2 650 S/C / Akrapovic Evolution / StopTech BBK
Track/Airstrip: 2011 997.2 Turbo S PDK / 725 HP / BBi suspension build
Beater: 2013 X5 3.5sport
YouTube Channel: https://www.youtube.com/channel/UCT1...eoFBszPIK0gf9w
Appreciate 0
      06-26-2013, 08:28 PM   #61
M3 Esq
Lieutenant Colonel
M3 Esq's Avatar
United_States
21
Rep
1,967
Posts

 
Drives: M3, 335i, X5
Join Date: Aug 2007
Location: CT

iTrader: (5)

Just downloaded Track Addict free edition for iPhone 5. Has anyone else used it? I have been fooling around with it on the street and it seems pretty cool. It seems to have very limited functionality but its free so who cares. I will try it at Lime Rock when I'm there on 7/12.
Appreciate 0
      06-26-2013, 08:47 PM   #62
Nugget
Major
Nugget's Avatar
19
Rep
1,495
Posts

 
Drives: 2011 135i
Join Date: Jan 2012
Location: Perth

iTrader: (2)

Garage List
2011 BMW 135i  [5.00]
I use Harry's Lap timer with a bluetooth GPS receiver. I've found it accurate to a 100th of a second when compared with official timing.
It has enough information for a novice like me, plus the video recording and overlay function is very easy to use.
eg.
[u2b]http://youtu.be/6SSqEqOSZso[/u2b]
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 06:47 PM.




m3post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST