# Key Takeaways - Either primary (radio wave "bounces back" off aircraft) or secondary (using [[transponder]]s) radar - Primary radar has several limitations which [[ADS-B]] has helped address - Either Airport Surveillance Radar ([[ASR]]) and Air Route Surveillance Radar ([[ARSR]]) # Details ## Primary Radar > [!quote] From [[Pilot-Controller Glossary]] > A radar system in which a minute portion of a radio pulse transmitted from a site is reflected by an object and then received back at that site for processing and display at an air traffic control facility. ### Limitations #todo :: add from AIM 4-5 ## Secondary Radar/Radar Beacon ([[ATCRBS]]) > [!quote] From [[Pilot-Controller Glossary]] > A radar system in which the object to be detected is fitted with cooperative equipment in the form of a radio receiver/transmitter ([[transponder]]). Radar pulses transmitted from the searching transmitter/receiver ([[interrogator]]) site are received in the cooperative equipment and used to trigger a distinctive transmission from the transponder. This reply transmission, rather than a reflected signal, is then received back at the transmitter/receiver site for processing and display at an air traffic control facility. # Additional Resources - [[AIM 4]]-5 ***Definition*** :: A system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, weather formations, and terrain. ***Additional Info:*** The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. The term has since entered the English language as a standard word, radar, losing the capitalization in the process. ***Source*** :: [[PHAK Glossary]] ***Meaning*** :: <u>Ra</u>dio <u>D</u>etection <u>A</u>nd <u>R</u>anging #acronym #glossary #concept