 By August 1942, U-boats were being fitted with radar detectors to enable them to avoid sudden ambushes by radar-equipped aircraft or ships.The first such receiver, named Metox after its French manufacturer, was capable of picking up the metric radar bands used by the early radars.This not only enabled U-boats to avoid detection by Canadian escorts, which were equipped with obsolete radar sets, but allowed them to track convoys where these sets were in use.