| 摘要 |
PURPOSE:To attain ease of circuit integration processing a signal at a base band and adoption the direct conversion system to execute delay detection. CONSTITUTION:The oscillating frequency from a local oscillator 2 is selected to the central frequency of a modulating wave, its output is divided into two, and a phase difference of 90 deg. is given between the two local oscillation signals by a phase shift circuit 3. The input modulation signal is frequency-converted into the base band by mixers 31, 32 by using the two signals as local oscillation signals. Low pass filters 41, 42 are porvided so as to eliminate a disturbing signal. An output of the filters 41, 42 is inputted respectively to one terminal of multiplier circuits 61, 62 and also inputted to the other terminal of the opposite multiplier circuits 62, 61 via delay circuts 51, 52. After the outputs of the multiplier circuit 61, 62 are subtracted by a subtraction circuit 7, the result is binary-coded by a polarity deciding circuit 8 and becomes a detected output. |
