A Global Positioning System better known as GPS helps in vehicle tracking, and also locating person or other assets on which it has been fixed. A GPS tracker basically comprises of GPS module to receive the GPS signal and calculate the coordinates. A GPS tracker may be of one of these three types, though presently most smartphones, being GPS Phones, can function in all these modes, depending on mobile applications installed.
GPS logger merely logs the position of the device at regular intervals in its internal memory. Modern GPS loggers have either a memory card slot, or internal flash memory and a USB port. Some act as a USB flash drive. This permits downloading of the track log data for added examination in a computer. Most digital cameras save the time a photo was taken. Provided the camera clock was reasonably correct, or the GPS was used as a time source, this time can be associated with GPS log data, to provide an exact location. This can be added to the Exif metadata in the picture file, thus geotagging it. These data loggers are used in some private Investigation cases to keep track of the vehicle or the fleet vehicle.
Data pusher is the most ordinary type of GPS tracking unit, used for asset tracking, personal tracking and as tracking system for vehicles. This kind of device pushes the position of the device as well as other information like speed or altitude at regular intervals, to a specific server that can store and immediately evaluate the data. Most of the modern GPS trackers provide data "push" technology, allowing refined GPS tracking in business environments, specifically organizations that use a mobile workforce, such as a commercial fleet. Typical GPS tracking systems employed in commercial fleets have two core parts: location hardware and tracking software. This grouping is often termed to as an Automatic Vehicle Location system. The tracking device mostly has hardwire installed in the vehicle; linked to the CAN-bus, Ignition system switch, battery. It allows gathering of extra data, which later get transferred to the GPS tracking server, where it is accessible for viewing through a website found over the internet, where fleet activity can be viewed live or historically using digital maps and reports. Thus the linked up structure of the device helps significantly in vehicle tracking.
GPS data pullers are also known as GPS transponders. Opposed to data pushers, that send the position of the devices at regular intervals through the push technique, these devices are always-on and can be queried as frequently as necessary by using pull technology. This technology is not in prevalent use, but a computer connected to the Internet and running gpsd is a good instance of this.
These can often be utilized in situations where the location of the tracker seldom needs to be known like placed in property that may be stolen, or that does not have stable source of energy to send data on a regular basis, like freights or containers.
The use of data pullers are becoming more common in the form of devices containing a GPS receiver and a cell phone which, when sent a special SMS message replies to the message with their location.
