| 摘要 |
1524573 Radio navigation STANDARD TELEPHONES & CABLES Ltd 29 Jan 1976 03508/76 Heading H4D A receiver for a radio guidance system including a transmitter transmitting signals as described in Specification 1,524,571 is described. The received signal, converted to intermediate frequency f IF , which retains the amplitude and phase information, is fed to balanced mixer 2 and also to frequency locking circuit 3 which a constant frequency output signal F IF(AV) - the average frequency of the predector stage output. This output signal is fed as one input to a single side band generator 4, the other input to which is from local oscillator 5 at the offset frequency 30 kHz. The output of single sideband generator 4 is fed to the other input of mixer 2, and the output therefrom carries the beat frequency amplitude and phase modulation previously imposed on the pre-detector output f IF . |
