New algorithms for hyperbolic radionavigation

Hardware and software aspects of the design of a microprocessor-based radionavigation receiver are discussed. The receiver uses the orange channel of the Decca Navigator transmissions, and is based on a design published by J.D. Last (1984). Unlike Last´s design, it computes a position fix by directly measuring the phase of the signal, using phase-locked-loop techniques, with software correction for interrupt latency. A phase determination algorithm is presented which compensates for local oscillator drift and for skew error due to movement of the vehicle during the measurement cycle, and which appears to be particularly resistant to errors due to skywave propagation effects. A further algorithm, based on number-theoretic techniques, is presented for performing zone identification by phase comparison using the master (6f) and orange (8.2f) transmissions only