| 摘要 |
PURPOSE:To constitute the device with low power consumption by delaying an input signal so as to make it coincident with the delay time of an output signal, mixing the both, using a signal obtained from the output of mixing through a narrow band pass filter as a local oscillation signal and mixing it with the input signal. CONSTITUTION:The input signal X is delayed (11), the result X' is made coincident with the delay time of an output signal Z. Then the delayed signal X' and the output signal Z are mixed at the 1st mixer 12 and its output passes through the narrow band filter 13. The filter 13 passes the frequency only being the difference of the signals X and Z. An output Y of the filter 13 is regarded as a local oscillation signal and mixed with the input signal X at the 2nd mixer 14. Only the frequency being the difference of the outputs of the mixer 14 is detected by a BPF15, the result (signal S) is amplified (16) and an output signal Z is obtained. The mean value of the amplitude of the signal Z is normalized into a required value, and an amplifier 16 is controlled by applying automatic gain control (17). Thus, the device with economy and low power consumption is constituted. |
