GPS tracker

A GPS tracking unit, geotracking unit, satellite tracking unit, or simply tracker is a navigation device normally on a vehicle, asset, person or animal that uses satellite navigation to determine its movement and determine its WGS84 UTM geographic position ( geotracking) to determine its location. Satellite tracking devices send special satellite signals that are processed by a receiver.

Locations are stored in the tracking unit or transmitted to an Internet-connected device using the cellular network (GSM/ GPRS/CDMA/ LTE or SMS), radio, or satellite modem embedded in the unit or WiFi work worldwide.

GPS antenna size limits tracker size, often smaller than a half-dollar (diameter 30.61 mm). In 2020 tracking is a $2 billion business plus military-in the gulf war 10% or more targets used trackers. Virtually every cellphone tracks its movements.
Tracks can be map displayed in real time, using GPS tracking software and devices with GPS capability.

Architecture

A GPS "track me" essentially contains a GPS module that receives the GPS signal and calculates the coordinates. For data loggers, it contains large memory to store the coordinates. Data pushers additionally contain a GSM/ GPRS/CDMA/ LTE modem to transmit this information to a central computer either via SMS or GPRS in form of IP packets. Satellite-based GPS tracking units will operate anywhere on the globe using satellite technology such as GlobalStar or Iridium. They do not require a cellular connection.

Types

There are three types of GPS trackers, though most GPS-equipped phones can work in any of these modes depending on the mobile applications installed:

Data loggers

GPS loggers log the position of the device at regular intervals in its internal memory. GPS loggers may have either a memory card slot, or internal flash memory card and a USB port. Some act as a USB flash drive, which allows downloading the track log data for further computer analysis. The track list or point of interest list may be in GPX, KML, NMEA or other format.

Most digital cameras save the time a photo was taken. Provided the camera clock is reasonably accurate or used GPS as its time source, this time can be correlated with GPS log data, to provide an accurate location. This can be added to the Exif metadata in the picture file. Cameras with a GPS receiver built in can directly produce such a geotagged photograph.

In some private investigation cases, data loggers are used to keep track of a target vehicle. The private investigator need not follow the target too closely, and always has a backup source of data.

Data pushers

A data pusher is the most common type of GPS tracking unit, used for asset tracking, personal tracking and vehicle tracking systems. Virtually every cell phone is in this mode per user agreement, even if shut off or disabled storing the data for future transmission.

Also known as a "GPS beacon", this kind of device push (i.e. "sends"), at regular intervals, the position of the device as well as other information like speed or altitude to a determined server, that can store and analyze the data instantly.

A GPS navigation device and a mobile phone sit side-by-side in the same box, powered by the same battery. At regular intervals, the phone sends a text message via SMS or GPRS, containing the data from the GPS receiver. Newer GPS-integrated smartphones running GPS tracking software can turn the phone into a data pusher (or logger) device. As of 2009, open source and proprietary