affordable lap timer

cossie1600

Lap Timer-Low cost Laptimer for $55.00

I am not affiliated with them, just saw it in the latest GRM.

SPOHN

Awesome find. Let me find some reviews. I'd like to have this. Going to have to rely on my GoPro for my times next weekend.

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wstar

Another alternative people should consider: if you have an Android-based phone, you can pick up a high-res external GPS unit fairly cheap (e.g. this one on Amazon which is what I use): http://www.amazon.com/BT-Q818XT-Qstarz-10Hz-Bluetooth-Receiver/dp/B003YCZINA, and use it with one of a couple of android apps depending on your focus. For road course and after-analysis, I prefer aLapRecorder HD, but if you want to see your splits displayed in a big font *while* you're lapping, you might prefer Trackmaster (downside is, it doesn't record OBD-II, while aLapRecorder will grab some OBD-II data (importantly, RPM) using one of the many cheap OBD-II -> Bluetooth devices out there).

There's similar software for iPhones but (a) I'm not an iPhone user so I can't really make suggestions and (b) it seems there are issues getting fast GPS updates on the iPhone for accurate timing, because Apple doesn't allow arbitrary BT GPS receivers to be used (e.g. see the explanation here: Compatibility)

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wstar

Here's a link to some youtube videos I've made based on the above HW/SW combo: MSR - 370Z - Sep8 - YouTube, TDE MSR-Houston Nov 6 2011 - YouTube. The lap/split timing with aLapRecorder is very accurate w/ the Qstarz unit in 5hz D-GPS mode, but as I said above, Trackmaster is the software that will give you a realtime heads-up display of current splits.

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cossie1600

What hertz can the OBDII logger log at? My datalogger logs at 10ghz while the obdII reader logs at random rates, makes it impossible to provide a consistent set of data.

Damn the external GPS are pretty pricey if you want 10ghz

wstar

On the GPS: The 818XT is switchable between 10Hz mode (with GPS only, no differential), and a programmable 1-5Hz mode that uses differential GPS (more accurate). From the forums for various lap timer software on android, it seems like the 5Hz D-GPS mode is actually better (more accurate, faster fixes, and still you're getting 5 position updates per second, which the software can extrapolate movement curves between).

OBD-II loggers vary a lot, it's kind of a murky area. With the PLX Kiwi and my phone, I get somewhere around 4Hz update rate most of the time. So for instance it will rarely catch the exact peak RPM just before a shift, but it's "close enough" for data analysis. Software like aLapRecorder logs all the inputs (phone G-sensors, OBD-II data feed, GPS data feed) and then reformats it into a combined data output file for rendering software (e.g. a single CSV file for RaceRender), which in turn probably does a little of its own smoothing and/or interpolation.

It doesn't really matter if OBD-II and GPS data line up at the same update frequency rate or not, or shouldn't with quality software on the other end interpolating them as approximating smooth value curves.

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wstar

On the expensive front, the ultimate thing seems to be ChaseCam. If you buy all the right options from them, you can have 1-4 cameras, accurate GPS + G-force, OBD-II, as well various other external sensors (independent RPM pickup, and a whole lot more), and it all logs in sync to a memory card. The problem is price. I just can't justify the 2-3K+ even for a basic setup that does a better job than my hackish Android stuff (which works "good enough" for amateur-level playing around anyways).

e.g. check out this sample video, where it's even logging all kinds of suspension/wheel-based data:

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Skeeterbop

That looks awesome!

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cossie1600

Also most OBDII plugs are long and straight, I believe they would get in the way of your legs. My datalogger has a $200 add-ons for RPM, but I doubt I will buy it since I only track 4-5 times a year. I can enter the gears in myself

speedworks

Wstar, pretty cool stuff. I'll admit, I am a little stupid on all of this stuff, but liked your videos. Hey, I race, and currently use a Gopro for my video, and nothing for data. Any recommendations - that can combine some of this stuff (and cheap)? I have both an Iphone and Android (wife) as options.

And here is something I have looked at, but not sure how it works, do I just download the app and use the phone as a camera?

Welcome to Harry?s GPS LapTimer

wstar

That's another point in favor of the PLX Kiwi (over some of the cheap knockoffs): it has a short plug with a cable to the bluetooth transceiver.

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wstar

I really couldn't tell you much about the iPhone options, I've only really explored this stuff on Android. To replicate what I'm doing w/ my android, it boils down to this, building up in layers here:

1) You get the app "aLapRecorder HD" from the Market on your phone. There's a free version that's limited in how many recordings it will save, and then you can buy the full-feature upgrade later if you want. Just by playing with the settings in this app, you'll figure out how to record track sessions on it with no other external devices. Just mount the phone to the windshield and hit Record and you're good to go, basically. It will interpolate from the phone's built-in GPS (low accuracy, updates once per second) for track position logging and raw speed data, and combine that with video. You can also replay your sessions inside the phone app later, and edit the track layout to add start/finish lines, section split markers, review your fastest/slowest laps/sections, etc. The replays also have overlaid gauges, etc on the phone, but it's not highly configurable.

2) If you want to add OBD-II data (currently, this is mainly for RPMs and for more-accurate speed updates (during hard braking/accel, GPS speed isn't quite as up-to-date as OBD-II-based speed)), you can buy basically any ELM327-compatible OBD-II-to-Bluetooth dongle. I like my PLX Kiwi. You do bluetooth pairing with the phone and the dongle, and then enable the devices in aLapRecorder's settings menu, and now you have this extra data in your replays.

3) If you want more accurate GPS, you buy a 5/10-Hz external bluetooth GPS unit. Again you pair it with the phone over bluetooth, and then configure aLapRecorder's settings to tell it to use the device for External GPS, and the improved accuracy is automatic for your new recordings.

Then, if you want to export data+video and lay it out on a big screen with virtual gauges, there are Export options in aLapRecorder. You could export a data-gauge blue screen, but it's slow to encode on the phone and very limited in its options, and then you still have to use video editing software PC-side to blend that with the camera video.

The route I prefer is I paid for a license to some cheap software called RaceRender 2. aLapRecorder can export all of the data into a single CSV file that imports into RaceRender 2 on your PC, and then you can lay out all of the gauges, synchronize with the raw video, and encode video (which is what generated my youtube videos linked above).

I ran down the basic costs when I first put this together over here: wstar's Journal, but basically assuming you already have an Android phone and a Windows PC for free, the rest is under $200.

As far as the GoPro goes, it's just a better substitute for recording on the phone's camera. You can disable video recording in aLapRecorder, so that it just logs the GPS/OBD-II/G-force-based data, and then mix your GoPro video with the exported data in RaceRender. You don't have to worry about timing the record button on both either, RaceRender will let you adjust the timing in sync, if you have some event that makes it obvious (e.g. blip the throttle hard on the starting grid while both are running, and then time the engine rev sound from the video with the RPM needle blipping from the data).

You could also run both the GoPro and the camera's phone for two different data views (front/rear?), and RaceRender can lay out one video embedded in the other, etc.

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speedworks

^^Ok, I think I understand most of what you said, thanks. My race car is a full-bred race car, so setup is a little different. I assume the OBD-II has to plug into an OBD-II outlet in a normal car? If so, then that is out of the question for me. And as for the GPS bluetooth (like TomTom's Iphone holder?), does that just need power and that's it? Sounds interesting, I might have to try one of these.

ChrisSlicks

I think I'm going to go with this one, is a good standalone system with solid analysis software. $400

AiM Sports - Solo

They also have a version that can log OBD-II data but it is a little pricey at $700.

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wstar

Yeah, if you don't have an OBD-II port on your racecar, you'd have to find some other solution for individual sensors or whatever.

I don't really know about TomTom and/or iPhone. The Qstarz unit I'm using has an internal battery that will go for several hours, and recharges via a Mini-USB plug, so you could just recharge it from a laptop or whatever before track time. (You also use the mini-usb to update the DGPS Almanac data and configure your rate settings, etc from a little Windows app. DGPS will work without an outdated almanac, but you get the very best results by being sure it's up to date before a track day (the almanac data lasts about a week or so)).

In my car, I just velcro down the GPS unit to the dash. For in-car power for the GPS unit and my phone, I put a dual-USB thingy in the center console 12V socket and I ran a micro-USB cable under the dash to my phone and a mini one for the GPS. Really not necessary though, you could pre-charge them and run on batteries.

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