GPS Inaccurate Speed

Discussion in 'GPS Technical Discussion' started by Quentin, Feb 25, 2020.

  1. Quentin

    Quentin

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    Has anyone experience parked vehicle with GPS reporting speeds over 100 MPH? I have 11 vehicles that have this issue. It is intermittent. The vehicles are in different locations and have a variety of GPS antennas. So far the only command point is the software being used, but the software is used on close to 800 vehicles. These 11 are the only ones showing speeds while parked in App bays.
     
    Quentin, Feb 25, 2020
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  2. Quentin

    Nuvi-Nebie Moderator

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    Is it possible to get a track log of any movement that the vehicles claims to have made while parked?, GPSs calculate their speed by plotting a location and then timing how long it takes to get to a new location, in other words it can't have a speed unless it thinks it has moved position
     
    Nuvi-Nebie, Feb 25, 2020
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  3. Quentin

    Quentin

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    Thank you for your reply! The tracking software shows the vehicles in the Fire stations and it is the software that reads the GPS and says the vehicle is going over 100 MPH.
     
    Quentin, Feb 26, 2020
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  4. Quentin

    Nuvi-Nebie Moderator

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    The Track log I was referring to in post #2 is the log stored in the GPS's memory

    How does the 'software' read the GPS ?, if this software is constantly reading data from the GPS in real time it is probably reading NMEA sentences, these send data every second containing location, time etc. So speed could be calulated in the GPS and sent in an MNEA sentence to the 'software' you refer to in post #3, in this case the 100 MPH will also be stored in the GPSs internal memory files, however I think it is much more likely that the 'software' is reading NMEA sentences that give the GPS's location and that the speed calculations are being done by the 'sofware', in this case either the software is creating the speed error or the NMEA data is being corrupted in some way which makes the 'software' get the speed wrong
     
    Nuvi-Nebie, Feb 26, 2020
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  5. Quentin

    Quentin

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    Thank you
     
    Quentin, Feb 28, 2020
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  6. Quentin

    Nuvi-Nebie Moderator

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    Question 1 : How does the 'software' read the GPS ?
    Question 2 : Can you examine the logs on the GPSs to see if they have stored any 100 MPH data?
     
    Nuvi-Nebie, Feb 29, 2020
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