GPS

Global Positioning System (GPS) is a widely-used, stable and inexpensive positioning technology. In general, it is accurate to approximately 1–10 metres. The system relies on satellite signals, which means it can normally only be used outdoors.

Technologies like Differential GPS (DGPS), High Sensitivity GPS (HSGPS) and Assisted GPS (AGPS) can be used to achieve greater precision, improved indoor coverage and faster positioning. GPS receivers are more expensive than Identification Tags (ID Tags) but their biggest disadvantage is that they require a lot of energy, which means receivers' batteries are quickly drained. This means that GPS technology is ideal for situations where other forms of tracking technology are out of reach.