 The radio equipment was located at the GATR (ground air transmitter and receiver) site, located at the crest of Eureka Hill Road, a few miles from the actual radar site.The GATR site was remotely located from the radar site to minimize interference from the radars into the radio gear.The GATR site ground-air communications equipment used single frequency UHF AM transmitter/receiver pairs, AN/GRT-3 and AN/GRR-7, covering frequencies between 225-400mHz.