| 摘要 |
<p>PURPOSE:To measure a frequency with high accuracy by comparing levels of plural frequency components within a band and performing encoding operation, and detecting an input frequency based on a sweep frequency at the change point of time of said code obtained by every sweep. CONSTITUTION:An input signal received by an antenna 1 is frequency-converted by a down converter 2 and then plural BPFs 3 and 4 are used to extract plural frequency components in the band. The respective extracted signal components are amplified by amplifiers 5 and 6 and detected by detectors 7 and 8, and the levels of the respective components are compared by a comparing circuit 10, and the result is encoded and transmitted to a signal processor 11. The processor 11 outputs a control signal to a sweep control circuit 13 according to the result of said comparison and a variable frequency oscillator 14 sweeps an oscillation frequency. The change of said code obtained as a result of sweeping and the current oscillation frequency of the oscillator 14 are used to detect the frequency of the received input signal.</p> |
