Wide area surveillance using SSR mode S multilateration: advantages and limitations

There is an increasing interest on the various applications of the SSR Mode S (secondary surveillance radar - mode selective) for air traffic and airport traffic management. This paper discusses the applications of ICAO standard Mode S signals, in particular in the down link channel around 1090 MHz, to locate and identify cooperating targets in the airport using multilateration (MLAT) and in the terminal area/en route using wide area multilateration (WAM). Performance analyses and some comparison with the more traditional SSR system (ATC radar beacon system : ATCBRS) are carried out.