Patent ID: 7570195

Claim:
A high-capacity surveillance and data link system able to locate and identify cooperating mobiles provided with a respective transponder device and a fixed infrastructure comprising fixed transmitting and receiving stations, the system being arranged to locate and identify the cooperating mobiles using Multilateration and/or Automatic Dependent Surveillance-Broadcast (ADS-B) techniques by means of transmission of position, identification, status information and ancillary data from the mobiles to the fixed receiving stations on the Secondary Surveillance Radar (SSR) Mode S channel, the system being further arranged to transmit commands, controls, nearby traffic information and ancillary data from the fixed transmitting stations to the cooperating mobiles on the Secondary Surveillance Radar (SSR) Mode S channel, the system being characterized in that each transponder is provided with a variable carrier frequency and the system is arranged to implement frequency-division multiple access in the down-link Secondary Surveillance Radar (SSR) Mode S channel using the variable carrier frequencies.