Categories

Search

How GPS Tracking Device works

Январь 11th, 2016 by homesecuirtycameras and tagged , , ,

Navigation employing GPS and inertial sensors is a synergistic relationship. The integration of these two types of sensors not only overcomes performance issues found in each individual sensor, but also produces a system whose performance exceeds that of the individual sensors. portable GPS tracking provides bounded accuracy, while inertial system accuracy degrades with time. Not only does the GPS sensor bound the navigation errors, but the GPS sensor calibrates the inertial sensor. In navigation systems, GPS receiver performance issues include susceptibility to interference from external sources, time to first fix, interruption of the satellite signal due to blockage, integrity, and signal reacquisition capability. The issues related to inertial sensors are their poor long-term accuracy without calibration and cost.

Today digital advancements make it possible to pre-program asset GPS tracking device on common routes you usually tread on with the vehicle and the trackers will also bookmark your work and home GPS coordinates. This allows the tracker to automatically notice changes to common routes and begin emitting readings that raise alerts well in advance. vehicle GPS locator tend to be very discrete and will have unique and personalized beepers and sounds alerting the driver or owner regarding an unplanned reroute and they are required to respond by accepting the same by pressing a secret hidden button.

One primary concern with using GPS as a stand-alone source for navigation is signal interruption. Signal interruption can be caused by shading of the GPS antenna by terrain or manmade structures (e.g., buildings, vehicle structure, and tunnels) or by interference from an external source. Each vertical line in this figure indicates a period of shading while driving 460 Integration of GPS with Other Sensors and Network Assistance in an urban environment. The periods of shading (i.e., less than three-satellite availability) are caused by buildings and are denoted by the black lines in the lower portion. (This experiment was conducted when five to six satellites above a 5º mask angle were available for ranging.)

GPS tracker works by the process of triangulation. (Technically, it is called trilateration because it calculates your position using distances rather than angles, but the concept is similar, and the terms are often used interchangeably.) When only three usable satellite signals are available, most receivers revert to a two-dimensional navigation mode by utilizing either the last known height or a height obtained from an external source. If the number of usable satellites is less than three, some receivers have the option of not producing a solution or extrapolating the last position and velocity solution forward in what is called dead-reckoning (DR) navigation. Inertial navigation systems (INSs) can be used as a flywheel to provide navigation during shading outages. The discrete-time nature of the GPS 3G in some equipment is also of concern in real-time applications, especially those related to vehicle control. if a vehicle’s path changes between updates, the extrapolation of the last GPS measurement produces an error in the estimated and true position. This is particularly true for high-dynamic platforms, such as fighter aircraft. In applications where continuous precision navigation is required, inertial sensors can be employed. An alternative solution is the use of a GPS receiver that provides higher rate measurement outputs.

Posted in General | No Comments »