A hyperbolic navigation system of the Loran type operating at 100 kHz. The system is similar to Loran A but has greater range and higher accuracy. It matches the phase of the signals instead of their envelopes, uses a different coding of the signals, incorporates a cesium clock to give more accurate control of the timing, and puts more power into the signals, which are in Golay code. Locations can be determined at distances up to 1 500 km over land and 3 000 km over water, but less accuracy is obtainable at greater distances. At a distance of 600 km from the master station, a good intersection will have an accuracy of about 150 meters. At 2 000 km, over water, an accuracy of about 500 meters may be obtained. However, an error of one cycle in determining phase would produce an error of about 8 km. Predictable accuracy is better than 400 meters within the region covered, and the precision is better than 18 90 meters.