iPhone 3Gs too slow for HLT ?

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KiSwiSje
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iPhone 3Gs too slow for HLT ?

Post by KiSwiSje »

I always use video mode, but lately the gps fixes have degraded to a point where the results are not useable anymore
laptimes are way off, or several laps are bundled, or laps are incomplete. The map in the overlay is all over the place.
Have recent updates made HLT too 'heavy' for a iPhone 3Gs? Is the iPhone/gps module malfunctioning? Is the combination of video and collecting data too much for the iPhone 3Gs ? It used to work pretty good, and fairly accurate too
Is there a way to check if HLT is using up all the processor power or something? What can I do to troubleshoot this problem? Tomorrow I will try and run without video, and see what that gives. (a brief try didn't show improvement)

which brings me back to a feature I have requested before ... set a minimum and maximum laptime possible for a track - that way wrong results will not mess up the lap list. (this would be a preference that every user has to set for every track individually)
it would be nice too if you could make a lap 'invalid' so it is not counted for fastest time or reference
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Harry
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iPhone 3Gs too slow for HLT ?

Post by Harry »

The "invalid" flag may be used for the feature request to keep recordings for incomplete laps too. That's on my list.

On speed: the 3Gs should definitively work. I had a small number of reports got very slow across the iPhone models. Is your front end VERY slow too? Data recording is not too processing intensive, so this should be the last tithing not working because of processing power.

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KiSwiSje
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Re: iPhone 3Gs too slow for HLT ?

Post by KiSwiSje »

the front end is a bit laggy, but not too slow
i turned off bluetooth - doesnt make much difference
i tried airplane mode - as i thought that would leave the gps on, but it does shut it down - so that doesn't help
I thought about taking the sim card out, but I think that even without sim it will keep in contact with the network to enable emergency calls
is there anything else I can shut down to give hlt more breathing room?
I do restart the phone from time to time, there is no software that is active at all time as far as I know, it is not jailbroken, it is up-to-date on ios
I do get the occasional crash when using hlt, but not during data capture (not since v16, anyway)
this afternoon I will have a go at using it without video
any ideas to troubleshoot this are welcome
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Harry
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iPhone 3Gs too slow for HLT ?

Post by Harry »

So if the front end is not slow, there is simply an issue with GPS accuracy, not performance. Double or missed laps, as well as the miss formed track displays in the overlays are clear indications for GPS issues.

The 3GS iPhone has a relatively weak GPS. Mid turn, I'd recommend an external solution like described on www.gps-laptimer.de/Compatibility.html

For you upcoming run, please make sure you place the iPhone in the best position for GPS: directly behind the windscreen.

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KiSwiSje
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Re: iPhone 3Gs too slow for HLT ?

Post by KiSwiSje »

The iPhone is mounted behind the windscreen, horizontal, for filming.

I restarted the iPhone. Bluetooth and wifi were turned off.
I did three sessions without video, and the results were very bad.
my laptimes on this configuration at the track average around 1:24 (first laps are warmup off course)

some screenshots to illustrate
first session, and lap details, to illustrate

I don't think there is much we can do, it seems the gps in this iPhone has some serious problems
I won't say it was super accurate, but I used to have pretty decent results, lap times within half a second correct when compared with transponder results at the Mettet track last year.
Attachments
gps fixes all over the place, third lap in the list
gps fixes all over the place, third lap in the list
IMG_1246.PNG (35.06 KiB) Viewed 3177 times
a pretty decent lap representation - 1st lap in the list
a pretty decent lap representation - 1st lap in the list
IMG_1245.PNG (38.46 KiB) Viewed 3177 times
session 1
session 1
IMG_1244.PNG (71.28 KiB) Viewed 3177 times
Last edited by KiSwiSje on Fri Sep 07, 2012 9:55 pm, edited 1 time in total.
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Harry
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Re: iPhone 3Gs too slow for HLT ?

Post by Harry »

Please follow the Preview row (press); press the small wrench in the top left; select the accuracy view (blue circles. Please post a snapshot here. Thanks.

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KiSwiSje
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Re: iPhone 3Gs too slow for HLT ?

Post by KiSwiSje »

Sorry - you were quicker to answer than I had time to edit and complete the message.

Just like would be expected from the results - the first lap has decent gps fixes, that third lap is somewhere in China, according to the gps fixes
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Harry
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Re: iPhone 3Gs too slow for HLT ?

Post by Harry »

Hi again,

Yes, the GPS positions are pretty inaccurate. A well positioned iPhone3G / 3GS should typically deliver 75% green and 25% yellow fixes - no red ones. The iPhone4s will be green all over the place. The only thing I can recommend here is playing with the mounting position. There seem to be some windscreen coatings including metal, maybe that's the case for you?

- Harry
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KiSwiSje
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Re: iPhone 3Gs too slow for HLT ?

Post by KiSwiSje »

2 mm poly carbonate sheet, no coating
as i said - it used to work pretty well
the results have degraded over time

one month ago:
http://www.youtube.com/watch?v=eMHvIHwshOg
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