Transponderans

Transponderans is the collective term for transponder systems that automatically respond to an interrogation signal with a predefined reply. These systems are used in aviation, maritime, satellite communications, and tracking applications. They provide an automatic two-way link that helps identify and locate objects without human intervention.

A transponder receives an interrogation on a specific frequency, decodes the request, and transmits a response on a different frequency or in a coded format. The reply data can include an identifier, altitude, position, and other status information.

In aviation, secondary surveillance radar relies on transponders to identify aircraft and exchange data. Modes A, C, and S specify the type of reply. The modern ADS-B system broadcasts aircraft position from onboard sensors, greatly improving traffic awareness.

In space, satellite transponders receive uplink signals, amplify or translate them, and downlink on a different frequency. They act as repeaters to enable telecommunications and broadcasting over long distances.

RFID transponders, including passive and active tags, respond when energized to enable asset tracking, access control, and supply chain management. Other uses include telemetry, remote sensing, and automotive immobilizers.

Security and privacy concerns include signal interception, spoofing, and eavesdropping. Countermeasures involve encryption, authentication, robust protocol design, and regulatory frameworks to minimize risk to safety and privacy.

The concept originated with IFF (Identification Friend or Foe) systems used in military aviation, later expanding to civilian air traffic control and satellite communications.

See also radar, IFF, ADS-B, RFID.