Q10Microwave Theory And Techniques
Question
Q.10. What is RFID and GPS?
Answer
RFID (Radio Frequency Identification) uses radio waves to wirelessly identify and track tagged objects via reader-tag communication; GPS (Global Positioning System) uses timed microwave signals from orbiting satellites to determine a receiver's precise position, velocity and time.
RFID: a wireless identification technology consisting of a small tag (containing a unique identifier, either passive — powered by the reader's own RF field — or active — with its own battery) and a reader that transmits an interrogating RF signal and receives the tag's response. Passive RFID tags are widely used for inventory tracking, retail anti-theft, toll collection (e.g., electronic toll tags), and access control cards, since they require no internal battery and can be extremely small and low-cost; active RFID tags, with greater range and data capacity, are used for asset tracking over larger areas.
GPS: a satellite-based radio navigation system consisting of a constellation of satellites (nominally 24, in medium Earth orbit) each continuously broadcasting a precisely timed microwave signal (around 1.2 and 1.5 GHz) encoding its own position and the exact transmission time. A GPS receiver measures the signal travel time from at least four visible satellites and, by trilateration (solving for the receiver position and clock offset that make all measured ranges consistent), determines its own three-dimensional position and precise time — the basis of navigation, mapping, and timing synchronization across countless civilian and military applications worldwide.