HyperFix is a third generation small position-fixing system developed to operate in the frequency band 1.6-3.4 MHz. HyperFix supercedes the earlier Hi-Fix system, development of which began in 1960. The fundamental operating principle is that of phase difference measurement in the receiver. The operating range over sea in full daylight conditions is approximately 700 km and during the night approximately 250 km, depending on the antennas used and prevailing propagation conditions. Over land and inland water, and during difficult atmospheric conditions, the range is correspondingly less. The accuracy obtainable depends on a number of factors, but under ideal conditions it is around 0.5 metres for a system operating at 3.4 MHz and 1 metre for a system operating at 1.6 MHz. HyperFix was designed to be a highly flexible system, meeting the needs of a wide variety of users. It is capable of being used with both temporary and permanent shore-based chains, and microprocessor control is used to enable the main system features to be programmable. It also enables a high level of flexibility automation of functions such as line identification and ambiguity resolution. Although single frequency operation is possible, normally two frequencies are always used, and this does not require any additional equipment. Frequency synthesis is used to generate the transmitter drive signal and phase comparison and control is carried out by digital signal processing.
HyperFix can operated in three ways, in Hyperbolic, Circular and Combined mode.