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How do GPS tracking devices work?

Discussion in 'Misc Electronics' started by Fester Bestertester, May 15, 2010.

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  1. Specifically, how do they transmit if they are, for example, inside a
    shipping container?

    Is there a hole drilled for an antenna? Or a fiberglas patch made to replace
    some of the steel top or side?

    Thanks.
     
  2. Sjouke Burry

    Sjouke Burry Guest

    The antenna must be able to look outside at a big slice of the sky,
    or the device wont work.
     

  3. They do not "transmit" at all.
     
  4. hamilton

    hamilton Guest

    GPS _receivers_ do not transmit.

    GPS _trackers_ may transmit.

    GPS Fleet Trackers do transmit, depends an which country on how they
    transmit.

    Some use cell phones, some use direct wireless transmitters.

    hamilton
     
  5. Jamie

    Jamie Guest

    Your package does not have any thing put in it or on it that GPS systems
    detect, otherwise, it would be an expense..
    The package is placed on the truck and logged in on the computer as
    to which truck it's on.
    They simply track the truck! Via Cell or dedicated system..

    They simply scan in/out at the pickup/drop off places.. The scanner
    logs it to the current position location.
     
  6. Those are PERIPHERAL sub-systems to a GPS system. GPS receivers do not
    transmit.
    None of which make contact with any GPS hardware.
     
  7. Many also transmit several vehicle condition data blips as well, so
    they can track and prevent breakdowns, and catastrophic breakdowns being
    the most important to avoid.

    Still has nothing to do with GPS other than that GPS is referenced when
    the system records a new system status file and transmits it back to a
    central server, which makes vehicle tracking a no brainer. It can even
    fail to get a reading sometimes, and it would still have no effect on
    tracking as a new, good reading will soon follow.
     
  8. hamilton

    hamilton Guest

    I think we are agreeing here.

    Glad to know I go it right. ;-)

    hamilton
     

  9. Nope. There is no such thing as a "GPS Tracker" other than some lame
    moniker some lame maker slapped onto one of their systems, which others
    then adopted. A system that USES a GPS receiver.

    There are transmitting trackers, which USE a GPS receiver to gain a
    position resolution. Tying them together by naming the entire system
    using the receiver name as a key identifier doesn't change the facts.
    They are separate systems.
     

  10. The fact is that at best, the damned things are nothing more than a
    trip log, even if they transmit their poll results to a remote storage
    location.
     
  11. Looks like the retarded ProTrolleus needs to be walked through things
    again.

    I hope that in your next life you are endowed with more brains than
    that of a gnat.

    ALL GPS receivers have some chrono/position logging function.

    If an idiot makes one and calls it a "tracker", there may or may not be
    a transmitter unit incorporated into it to send back log entries to a
    remote server, where a third party could use the data to "track" the
    location of the operating "tracker" system.

    The GPS unit utilized is still a component of the system, not the
    system itself.
    Basic concept of GPS (Quoted From Wikipedia)

    A GPS receiver calculates its position by precisely timing the signals
    sent by the GPS satellites high above the Earth. Each satellite
    continually transmits messages which include

    * the time the message was transmitted
    * precise orbital information (the ephemeris)
    * the general system health and rough orbits of all GPS satellites
    (the almanac).

    The receiver utilizes the messages it receives to determine the transit
    time of each message and computes the distances to each satellite. These
    distances along with the satellites' locations are used with the possible
    aid of trilateration, depending on which algorithm is used, to compute
    the position of the receiver. This position is then displayed, perhaps
    with a moving map display or latitude and longitude; elevation
    information may be included. Many GPS units show derived information such
    as direction and speed, calculated from position changes.

    Three satellites might seem enough to solve for position, since space has
    three dimensions and a position near the Earth's surface can be assumed.
    However, even a very small clock error multiplied by the very large speed
    of light[22]—the speed at which satellite signals propagate—results in a
    large positional error. Therefore receivers use four or more satellites
    to solve for the receiver's location and time. The very accurately
    computed time is effectively hidden by most GPS applications, which use
    only the location. A few specialized GPS applications do however use the
    time; these include time transfer, traffic signal timing, and
    synchronization of cell phone base stations.

    Although four satellites are required for normal operation, fewer apply
    in special cases. If one variable is already known, a receiver can
    determine its position using only three satellites. (For example, a ship
    or plane may have known elevation.) Some GPS receivers may use additional
    clues or assumptions (such as reusing the last known altitude, dead
    reckoning, inertial navigation, or including information from the vehicle
    computer) to give a degraded position when fewer than four satellites are
    visible (see,[23] Chapters 7 and 8 of,[24] and [25]).


    GPS receivers pick a few satellites and prove position based on the
    arrival times of each satellite's signals.
    Why are you a retarded Usenet troll?
    There should be a gene pool clearing crew after you and yours.
    It certainly appears that he has influenced you.
    None of your goddamned business, troll boy.
    You are a goddamned utter retard.
     
  12. You probably do not even know how Lo Jack works either.

    It too has not a goddamned thing to do with GPS.

    Lo Jack is ONLY a radio locator beacon, and nothing more.

    It sends OUT pings and that is what the cops find. There is no data
    transmitted at all. The pings only consist of a carrier and unique ID
    pulsing. The Lo Jack Transmitter gets turned on when a satellite or
    ground based transmitter sends out commands to turn on a specific Lo Jack
    device. The one that is in the car that just got reported stolen. All
    the other Lo Jacks do not turn on because they are initialized by the
    transmitter in a unique ID manner.

    Lo Jack on a laptop simply works by reporting the laptop's assigned IP
    address to the Lo Jack security servers. They then locate that IP
    address' 'subscribed' 'owner', and execute a search warrant on that
    person, or resolve who the culprit is until they finally get him.
     
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