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Thread: Issues with the BT-Q818XT

  1. #1
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    Mar 2019
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    Issues with the BT-Q818XT

    I've been using TrackAddict / RaceRender for a while now, but I've been using my phone's internal GPS. However, I am getting to the point where I want more accurate positioning data to compare autocross runs. I bought a Qstarz BT-Q818XT and, paired it with my phone, and configured TrackAddict to use it. However, the resulting maps are completely insane.

    Screenshot_20190713-111107_TrackAddict.jpg

    Now, I just took this thing out of the box and paired it. Is there something more I need to do, either with the device or within TrackAddict, to make it work properly? I haven't connected the module to my PC and set up the "A-GPS" functionality yet, but am probably going to do so just to see if it helps.

    I know it's a popular module so I figured I'd ask here first.

  2. #2
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    Jul 2019
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    I just bought one too, and the first day wasn't very successful:

    Screenshot_20190715-171453.png

    I seems to not line up with the track?

    Then a bit later on it went nuts:

    Screenshot_20190715-171844.png

    I also just took it out of the box and paired it, without doing anything else.

    This was the first thread I found when I searched, and since it is so recent I thought I would just tag along.

  3. #3
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    Mar 2019
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    Heh, at least yours isn't showing your car reaching orbital velocity, but clearly its just as useless for trying to get precise data.

    Near as I can tell so far, it's an issue with TrackAddict. I used to use another lap timer app (not naming names because I like TrackAddict better, but it's the other popular and inexpensive one). I fired it up, set it up to use the Qstarz module, and it worked perfectly fine.

  4. #4
    My Qstarz is a few years old, but at that time I just paired it out of the box and its performed perfectly.

  5. #5
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    Mar 2019
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    I've been digging into this more. So far, I still am unable to reproduce this issue in another track app. Meanwhile, I cannot get a "clean" session out of TrackAddict. I exported the raw data to look at the GPS coordinates TrackAddict reports and I am seeing massive shifts in longitude (-96.0291547 to 15.1833333) but latitude stays reasonable.

  6. #6
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    Mar 2019
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    I *may* have fixed it. I've now gotten three successful tests after re-configuring the module, whereas before I didn't have a single success.

    I plugged the module into my laptop, turned it on to the first position (labeled as 1 Hz), and ran the utility. At someone else's suggestion (and since the data seems worthless?) I turned off GSV. This significantly reduced the bandwidth needed by the device and seems to have made a huge impact on the reliability of it. I also set the 1 Hz switch position to run at 5 Hz instead, which still leverages DGPS and (in theory) provides for more accurate data.

    More testing needed, but this sure seems really promising.

  7. #7
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    Jul 2019
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    OK, I turned GSV to 0 as well.

    I set the 1Hz switch to use 5Hz, but will try and stick to 10Hz first, and only use the 5Hz if it is still fubared.

    the bandwidth dropped from 43% to 20% at 10Hz with GSV at 0, so that is promising, and the output in the data dump screen was a lot simpler.

    Will let people know if it helped when I get a chance to test it.