APPARAT FOR MOTTAGNING AV FASKORREKTIONSSIGNALER FRAN EN KORREKTIONSSIGNALSENDARE OCH FOR FASKORREKTION OCH FASDIFFERENTIERING AV SIGNALER MOTTAGNA FRAN NAVIGERINGSSYSTEMETS ORDINARIE SENDARE AV EN HUVUDMOTTAGARE

摘要

In a sequential-transmission phase measurement radionavigation system, such as the OMEGA radio-navigation system, phase correction signals are transmitted by a network of transmitting stations to provide phase corrections over a predetermined area. Each phase correction transmitting station compares the measured phases with preset theoretical phases and provides a phase correction signal for each measured phase. The phase correction signals are time multiplexed with a multiplex frequency between 10 and 30 times the repetition rate of each of the sequential transmissions of the radio-navigation system, the multiplexing being synchronous with the sequential transmissions. The multiplexed signal is phase modulated on a carrier with a low modulation index. At a receiver the multiplexed phase correction signal is demodulated and demultiplexed to provide the phase correction signals which are used to modify the measured phases at the receiver.