The enforcement of blackout in the United States at the outbreak of the war necessitated that, in addition to the blackout of municipal lights, the navigational aids in continental waters had also to be extinguished or silenced. (See blackout). To perform this action by manual labor consumed far too much valuable time and so it became expedient that a more swift method be devised. By 1942, Headquarters developed a radio control system for aids to navigation intended primarily for blacking out unattended lighted aids by means of radio signal. This system consisted of a control station transmitting specially coded ultra high frequency signals with a special receiver mounted on the buoys or other aids which responded to code signals and operated relays of gas valves to extinguish or relight gas lights or to turn off or on other types of aids. The system was designated by the coined word "RACAN" which was later changed to ANRAC to avoid confusion with RADAR beacons or RACONS.
The receiving control, in combination with an electric relay, was used to operate an electric bell signal to notify light keepers at outlying stations, lamplighters or buoy patrols that aids were to be extinguished. Such installations at certain visual vantage points permitted the person notified to observe the extinguishment procedure and to take the necessary action in those cases where receiving equipment proved faulty. This system of notification was considered as a means of relieving commercial communications facilities and was carefully planned in order to avoid serious results in case of testing operations. Weekly operational tests were made and all failures were reported in detail to Headquarters.
A transmitter and a keying unit were required for each control station, together with an emergency standby. A single control transmitter operated all receiving controls within its working radius of approximately 7 miles even though it was not within visual range of the receiving station. (The working radius of the control transmitter beyond its visual range depended on the size and nature of the obstruction; ordinary obstacles did not materially affect the working radius of a control transmitter.)
After a thorough study of the use of ANRAC, the District Coast Guard Officer, 13th Naval District, requested Headquarters' authority to install the equipment with Cape Disappointment Light Station as the control unit and the following buoys to be equipped with receivers:
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