| 摘要 |
PURPOSE:To obtain a phase difference without any influence of a noise even when the signal-to-noise radio of an input signal is inferior by calculating the sum of and difference between the 1st and the 2nd input signals, and then calculating the difference between signals obtained by passing the sum and difference through narrow-band amplifiers and detecting them. CONSTITUTION:An input terminal 1 is connected to the 1st inputs of adders 2 and 3, whose outputs are connected to inputs of detectors 6 and 7 through the narrow-band tuning amplifiers 4 and 5 respectively. The output of the detector 6 is connected to the in-phase input of a subtractor 8, and the output of the detector 7 is connected to the opposite-phase input of the subtracter 8, whose output is connected to an output terminal 9. The 2nd input of the adder 2, on the other hand, is connected to the output of a voltage-controlled oscillator 10, whose output is connected to the 2nd input of the adder 3 through a phase inverting circuit 11. Thus, even if the signal-to-noise ratio of the input signal is inferior, its influence is removed through the narrow-band tuning amplifiers and the phase difference is detected without any influence of a noise. |
