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Compass and Elevation

Discussion in 'Roadster: Technical' started by vfx, Oct 27, 2010.

  1. vfx

    vfx Well-Known Member

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    Not sure how long it's been like this but my upper right touchscreen corner just says N/A.

    Is this from the last firmware or is my GPS kaput?
     
  2. shark2k

    shark2k Member

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    It's telling you you are in North America? (sorry, couldn't help it :tongue:).

    -Shark2k
     
  3. cinergi

    cinergi Active Member

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    Mine's been accurate since I got it (haven't checked for ~1 week though). I wonder if setting a special charge rate somewhere would stick (or un-stick if you moved the car)?
     
  4. Doug_G

    Doug_G Lead Moderator

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    It says N/A when you're parked. Dumb question... have you checked it while moving?

    Doug
     
  5. vfx

    vfx Well-Known Member

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    While driving to work today.
     
  6. bolosky

    bolosky Member

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    I had this happen, and it was a dead GPS antenna. I think that I got a yellow fault with it, though, so you probably have something else wrong.
     
  7. scott451

    scott451 KWH-PWR#1349Sprt,S Sig#96

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    Did you get your lights upgraded to the "fog free" version? The GPS is right next to the Headlamp on the drivers side (2008). Maybe it got damaged during the upgrade?
     
  8. vfx

    vfx Well-Known Member

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    No headlight changes and no yellow fault light.

    I noticed on the way home that the upper white letters where the compass (now) reads N/A also has the smaller light blue elevation letters also read N/A as well.
     
  9. NigelM

    NigelM Recovering Member

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    Does anyone know if the "Elevation" continues in 100ft increments? I'm just curious as I went over the Sunshine Skyway today and finally saw my readout jump to 100ft and then 200ft. It normally stays constantly on 0ft in Sarasota.
    214.jpg
    BTW, very cool ride!

    (Now also curious if you found out what your problem was Eric?)
     
  10. doug

    doug Administrator / Head Moderator

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    If it doesn't it should. I wouldn't trust GPS based altitude to better than 100ft. (It's basically due to geometry why GPS does much better at 2D horizontal measurement than it does for altitude.) A calibrated barometer does better than GPS for altitude, but I don't know if the Roadster uses one.
     
  11. TEG

    TEG TMC Moderator

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    For what is is worth, I was charging the other day at a public charge spot, and was looking through the various menus on my Leaf's nav screen. On the GPS info screen it showed my elevation as -62 feet. I know for sure I wasn't below sea level.
     
  12. doug

    doug Administrator / Head Moderator

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    This is quite common. GPS isn't accurate on that scale and a barometer has to be calibrated for changes in the weather.
     
  13. TEG

    TEG TMC Moderator

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    Yeah, I think that is particularly notable for pilots trying to land on instruments that need to make sure they know when they are about to touch down...

    Altimeter - Wikipedia, the free encyclopedia
     
  14. NigelM

    NigelM Recovering Member

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    #14 NigelM, Sep 6, 2011
    Last edited: Sep 6, 2011
    Huh? That makes no sense as GPS satellites are in geostationary orbit. Your GPS doesn't stop working at night....The perils of Wikipedia!
     
  15. dpeilow

    dpeilow Moderator

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    GPS is in medium earth orbit not GEO.

    As the satellites move around you can get situations where all are near local horizon.


    ConstellationGPS.gif
     
  16. TEG

    TEG TMC Moderator

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    #16 TEG, Sep 6, 2011
    Last edited: Sep 6, 2011
    Mesmerized by the GIFANI...
    Looks remarkably like visualizations of electrons orbiting a nucleus, eh?
    atom.gif [​IMG]
     
  17. dpeilow

    dpeilow Moderator

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    It's about to get a lot more crowded soon too.

    The Galileo system will have assured "safety of life" signals that can give accurate altitude information to airliners, for example. GPS III will have similar. A tri-system receiver that can use both these and Russia's GLONASS would mean you'd almost always have satellites overhead.
     
  18. NigelM

    NigelM Recovering Member

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    I stand corrected! And also slightly dizzy from watching that graphic flying round.... Although I think it also proves my point as your graphic never shows less than 7 satellites visible at any one time.
     
  19. TEG

    TEG TMC Moderator

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  20. TEG

    TEG TMC Moderator

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    For whatever reason, I think that much of the time a particular receiver may not be able to lock onto all ~7+ at once.
    Maybe they only support less channels, or they found one closer to the horizon sooner, or the antenna is obstructed by something. Particularly in a car there may be some directional preference on the reception. I suppose that some of the sats are out of operation at times too.
    I don't recall exactly, but I think I have noticed GPS receivers typically only using 3 or 4 at a time.
     

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