Wide Area Multilateration (WAM)
From SKYbrary Wiki
Wide-area Multilateration (WAM)
Wide-area multilateration is a Surveillance technique that exploits the 1090 MHz transmissions broadcast from aircraft. From these signals it can create a track containing parameters such as aircraft identification, position, height, etc. Active interrogation is also possible in order to trigger transmission.
Although the manner in which WAM constructs Surveillance data differs significantly from Automatic Dependent Surveillance Broadcast (ADS-B), the synergies between these two Surveillance techniques in addition to their high performance and lower cost are expected to bring significant operational benefits. Consequently, composite WAM/ADS-B systems are widely offered by industry and deployed by ANSPs in Europe and worldwide, thus exploiting these synergies.
The optimal mix of the various Surveillance techniques (Transponder Mode S, ADS-B, WAM) will however depend upon the local environment, operational needs and business case, from an overall ATM Network viewpoint.
ADS-B and WAM are key enablers of the future European ATM Network, contributing to the achievement of the Single European Sky (SES) performance objectives, including safety, capacity, efficiency and environmental sustainability.
See EUROCONTROL CASCADE web-site.