The present document specifies technical characteristics and methods of measurements for the following equipment: 1) Interrogators transmitting in the 1 030 MHz band, used in Mode S multilateration equipment in an Advanced Surface Movement Guidance and Control System (A-SMGCS). 2) Receivers, receiving in the 1 090 MHz band, used in Mode S multilateration equipment in an Advanced Surface Movement Guidance and Control System (A-SMGCS). Antennas for this equipment are external and passive without an additional amplifier. The present document does not apply to equipment which includes a transponder function, to ground vehicle locators and to reference transmitters which do not contain receivers for the purpose of replying to interrogation.