Anthorn Radio Station - VLF Transmitter

VLF Transmitter

The VLF transmitter is used primarily for transmitting orders to submarines on 19.6 kHz. Its callsign is GQD. VLF transmissions are relatively unaffected by atmospheric nuclear explosions and Anthorn was once part of the link between Fylingdales early warning radar, North Yorkshire, and the United States' air defence system.

It is a NATO facility, controlled from Northwood Headquarters along with three other VLF transmitters in Norway, Germany and Italy. In accordance with the procedure for NATO projects, the project was the subject of a competition among the organisation's member countries. The British Post Office, acting as technical adviser and agent of the Ministry of Defence, chose the site, negotiated the contract and supervised the work, with the assistance of the Ministry of Public Building and Works. The contract was placed on 26 October 1961 with Continental Electronics Systems Incorporated of Dallas, Texas. This firm had already built a similar but much larger station in Maine, USA. Work began in 1962 and the station was accepted on behalf of the MoD in November 1964.

Originally, the station was designed to radiate a single telegraph channel at up to 45.5 baud and at powers ranging from 50 kW at 16 kHz to 100 kW at 20 kHz. The carrier frequency was to be stable to one part in 108 over a month. Subsequently the data rate was increased to 50 baud and the carrier stability improved.