Autocross setup didn't record any laps

[vmbray]

About a month ago I did an autocross and no laps were recorded. I didn't notice at the time (and forgot to do the record ahead and let it restart). I set directions on the start/stop also. The only weird thing was that the stop was listed before the start, no idea if that matters. I was having a great day and was focused on driving so it was no big deal but just trying to understand for the future.

My question is, would it cause that to have POI from previous events hanging around? I see now I can purge those out and I guess that's the thing to do for maintenance purposes.

I tested this morning with directions set on start/stop and it worked perfectly so I don't think it's a bug but maybe there was an update that fixed something.

Thanks as always!
Vince

[Harry]

Hi Vince,

I doubt it has been a problem with the app but either a problem with the triggers or with GPS accuracy. When setting directions, please make sure you use the correct degree system, i.e. 1 (instead of 0) for North, 90 for East, 180 for South, and 270 for West (and certainly any value in between). In case direction is the opposite direction (+-90 degree), it will not trigger.

Widow triggers disturb operation in that it will add lap splits in places you do not expect. However, it will not lead to the situation described, with nothing recorded at all.

Finally, please make sure you have good GPS reception by placing the smartphone centered into the windscreen.

- Harry

[gplracerx]

You must have an external GPS with at least a 5Hz rate for autocross data recording. The Dual XGPS160 at 10Hz is what I use. The 1Hz rate of the internal GPS will not give you what you want.

Here's a course plot using the iPhone internal GPS and a VBox Sport GPS at 20Hz.



Not only do you not get many points, but they're not precise enough for autocross.

[vmbray]

Thanks Harry. I'm sure the triggers were set up correctly - does it matter if the stop trigger was listed first?

here's the site, north is up (I know this to be true and also apparently on google maps north is always up on screen on the desktop browser version). I had the start tagged 270 and the finish 90. I double checked this before the event and also after while I was crying in my beer

Again not crucial and seems to be working, the order of the triggers was the only thing I could see that made sense. I thought that about the POIs that they would just maybe cause havoc while running so I purged all of them.

[Harry]

Triggers and POIs are sorted by latitude when displayed, the order has no meaning for triggering.

- Harry

[gplracerx]

You can test the start and finish triggers while doing a course walk. Go to Expert Settings/ Trigger Detection and turn on Allow Low Speeds. I also recommend setting the detection corridors, especially the Wide corridor which is used when a direction is set, to the minimum of 5m. With the default setting, it's very likely that, for a tight course at a small venue, you can trip a trigger when on the course when you don't want to. That's something else you need to check when walking the course.

For settings changes, you must send the app to the background and bring it back. In fact, it's a good idea to do that after you define the trigger points because that's when they're stored.

[vmbray]

Thanks I didn't know about low speed detection I will try that. I was at a track day event at Roebling road and loaded that track and again no laps were recorded. I had to leave early so only did one session but that's a preconfigured track that is known good. Not sure what's happening but when I test, it works. Thanks for any input!

[vmbray]

I tried this again yesterday with a very simple test. In a parking lot I set a simple autocross course. Start and finish with no directions. Worked perfectly. Then added direction to the triggers and it immediately stopped working.

Also a couple months ago I was at Roebling Road for a track day and the app did not trigger at all. I loaded up the track just now and it has a direction on the start.

This is getting pretty frustrating because there is definitely some issue with directions on start/finish but obviously it's not affecting everyone. Could this be a gps issue? I used a compass app to set start/finish directions and I know that there is leeway in the angle so it doesn't have to be perfect. Also I know from living here that my directions are accurate enough to trigger. What can I do to further narrow down the problem?

Thanks!

[Harry]

First step is to verify data is entered correctly. As you used a compass chances are good you did it right, but to work around an issue here, 90 is East, 180 is South, etc.

Besides filtering driving direction with these POI directions, another difference is in the corridor applied. For POIs with a direction defined, LapTimer will always use the wide corridor instead of your corridor selected. You may check your Expert Settings for all the corridors, the wide one should be 40 (meters).

To further trouble shoot this, you may send an export of the laps you recorded without directions defined (.hlptrl) as well as your track set. Use the track certificatuon function (enter the user defined POI Set shown in Lap List for you AX) to send the .hpoil file and change the addressee from Tracks to Harry@gps-laptimer.de

I'm pretty sure the problem is around the configuration, a general issue would have resulted in hundreds of trouble tickets each weekend

Harry

[gplracerx]

Are you using a start line or standing go? A standing go doesn't care about direction. Once you're staged, it triggers when it sees acceleration. For a start line with direction, you have to be moving fast enough that the GPS can establish a direction. Unless you also have low speed allowed set, you have to be moving faster than some minimum speed. The map display will show the trigger location and direction. The red arrow points in the direction of travel.