Compara mètodes

	TCAS	Navegació Proporcional	Propagació TLE SGP4
Camp	Aeroespacial	Aeroespacial	Aeroespacial
Família	Process / pipeline	Process / pipeline	Process / pipeline
Any d'origen	1989	1957	1970s
Autor original	FAA, ICAO	Lin-Hsiung Chu	NORAD, USAF
Tipus	Avionics system	Guidance law	Propagation method
Font seminal	Federal Aviation Administration (2017). Traffic Collision Avoidance System (TCAS II). Technical Standard Order TSO-C119c.	Knox, W. P. (1971). On optimal proportional navigation. IEEE Transactions on Aerospace and Electronic Systems, AES-7(3), 417–426.	Vallado, D. A., Crawford, P., Hujsa, R., & Kelso, T. S. (2006). Revisiting Spacetrack Report Number 3. In AIAA/AAS Astrodynamics Specialist Conference.
Àlies	TCAS II, ACAS, traffic avoidance	PN, PN law	SGP4, TLE propagation, simplified perturbations
Relacionats	3	3	3
Resum	TCAS (Traffic Collision Avoidance System) is an airborne safety system that detects nearby aircraft using radar and mode C altitude reports, then provides traffic advisories (TAs) and recommended collision avoidance maneuvers (RAs) to flight crews. Mandated globally on commercial aircraft since 2000, TCAS is considered a last line of defense against mid-air collisions. TCAS II is the most common variant; TCAS I is a simplified advisory-only version for general aviation.	Proportional Navigation (PN) is a guidance law that generates command accelerations proportional to the rate of change of the line-of-sight angle between a pursuer and target. Introduced by Lin-Hsiung Chu in the 1950s, it became the foundation of modern missile guidance systems. PN solves the pursuit-evasion problem by ensuring that the pursuer intercepts a moving target with minimal computational overhead.	SGP4 (Simplified General Perturbations 4) is a rapid orbital propagation method that predicts satellite position and velocity from Two-Line Element (TLE) sets published by NORAD. Developed in the 1970s, SGP4 accounts for atmospheric drag, gravitational perturbations, and solar radiation pressure using simplified analytical models. SGP4 is the de facto standard for space surveillance, conjunction assessment, and satellite tracking.