Satellite navigation using integral Doppler data-The AN/SRN-9 equipment

The U.S. Navy's all-weather satellite navigation system has been in operational use since July 1964. Satellites transmit orbital information and constant-frequency carriers so that a shipboard Doppler receiver and computer can obtain an accurate position fix of a ship at the time of a satellite pass above the ship's horizon. The system is available for use by research vessels in oceanography and geophysics. This paper presents a very brief review of the navigation system, a theoretical description of the satellite Doppler data received, and a simplified description of the computations required to obtain a navigation fix. Emphasis is placed upon one experimental version of shipboard equipment, the AN/SRN-9 integral Doppler equipment. This equipment has been designed especially for use by surface ships where cost, size, weight, and power requirements are important considerations. Similar equipments have been undergoing sea trials to determine their applicability for research vessels if a post-analysis capability for determining ship's position is a critical requirement. The results have amply demonstrated the potential usefulness of the AN/SRN-9 for oceanography.