Qstarz BT-818X error?

I did 2 sessions in the same 07 Porsche Turbo and got maps looking strange. The map on the bottom from another car is how Lime Rock should look. Both times I placed it on an aluminum cross brace below the rear window...it's possible the vibration or proximity to the motor did this???

Anyone seen this before???

mapmf.jpg
By tentenths

Comments

  • Yes I've seen that before. I think it can happen for many reasons:

    1) Visibility to sky, maybe the installation location was not as good in that car, or maybe the windshield glass filters GPS signal.

    2) Satellite situation due to weather etc.

    3) High G-forces. Maybe can be improved by 1 and 2 points but could be it can't be totally avoided with this car.
  • I have seen this a lot more then once on bikes and cars. It has nothing to do with vibration or anything like that in my opinion.
  • Exact same problem using same gps unit as i described in earlier thread last week. Works perfect for some laps then drops out on others when gps location on bike is identical and weather perfect all day. Shows minimum 6 or more satellites fixed too when drops out but colour changes to orange line from green. Trying again this weekend. Could it be interference from ignition system as i did have a misfire last time out?
  • aolaol
    edited September 2009
    This goes well beyond my knowledge of these devices ... I could only guess....

    But if the line goes to yellow or red, it's definitely dropping some of the satellite locks. Why that happens, I don't know. Poor visibility to sky or the weather? Could be interference too, I guess.
  • Hi aol. Perfect data last time out, BUT noticed the gps was in 1 hz mode. I didn't change it (not intentionally anyway) Will be long time before get to test in 5 hz in a race again early next year, but could be coincidence i guess and due to ignition problem?
  • edited October 2009
    apparently if the battery completely drains on then they default back to 1hz...flaw!

    I now check the rc screen with the sat time to confirm it shows 5hz before the first run of the day.

    As you know, to change it to 5hz, you must use their wanker software...which in my tests...if you set it to 5hz, then close and open it again it shows 1hz even though it is still in 5hz. You need to set it to 5hz. Quit the program and check in RC.

    I still think these errors are caused by spurious emissions around electrical components.
  • I agree 10/10th. I'll reset to 5hz and check again now misfire cured. Hopefully I'll get out once more for testing at least before end of year.
  • to update... I just bought 2 more gps receivers and I thought they were 818ex but they are 818x and these appear to be better...I only think this because they cost more and they have more channels and they have a 5hz switch instead of having to use the software to set them,,,drawback is that the switch could be accidentally moved.

    So the post above only applies to 818EX.

    If anyone has any info regarding the difference between the 2 models I would be interested as I can still exchange them.

    thanks
  • AND...I just noticed a screen shot of RC right on the side of the box!!!

    nice!
  • aolaol
    edited October 2009
    Hehe, that's a nice touch isn't it :) There is some older version of RaceChrono included on the CD. I'm not sure what is the difference between EX and X, as I've never had the time to compare the specs sheet.
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