CH was not able to detect aircraft at low altitude, and from 1939 was normally partnered with the Chain Home Low system, or AMES Type 2, which could detect aircraft flying at any altitude over 500 ft (150 m). Ports were covered by Chain Home Extra Low, AMES Type 14, which gave cover down to 50 ft (15 m) but at shorter ranges of approximately 30 miles (50 km). In 1942 the AMES Type 7 radar began to take over the job of tracking of targets once detected, and CH moved entirely to the early warning role.