| 摘要 |
PURPOSE:To economize a receiver for a hyperbolic navigation by detecting the phase difference in a digital processor to integrate the circuit of the receiver and reducing the number of expensive voltage controlled crystal oscillator to one. CONSTITUTION:A voltage controlled crystal oscillator 122 is controlled by comparing in phase a master station intermediate frequency signal with the frequency divided output signal of the output obtained by mixing the outputs of a local oscillator 127 and the oscillator 122, and thus synchronized in phase with the received signal. The output of the oscillator 127 is applied through a synthesizer 128 and second frequency divider chain 148 having substantially equal frequency division to both inputs of a phase difference detector 118 to cancel the variation in the oscillated frequency of the oscillator 127 by the phase difference detector. Thus, the intermediate frequency can be lowered to reduce the operating frequency of phase tracking filters 102-104 and phase difference measuring circuits 108-110 all to less than several MHz. Thus, they can be readily integrated. |
