| 摘要 |
PURPOSE:To increase a detection speed by detecting the constant time interval when the input signal of a peak detector is maximum on the basis of the output signal of the detector and the output signal of a chirp oscillator. CONSTITUTION:An output which is delayed behind the output of a tap 61 by a constant time interval T1 is send out by a tap 62, an output which is delayed behind the output of the tap 62 further by the equal constant time interval T1 is sent out by a tape 68, and outputs which are delayed by the equal time interval T1 are sent out by taps 64 and 65 similarly. The chirp oscillator 9 outputs a signal which varies said constant time interval T1 of a delay line 6 within a constant time to the delay line 6. Thus, the constant time interval is varied linearly by the chirp oscillator 9 and then the output of the detector 8 is in a mountain shape having a peak. A ship speed detector 11 inputs the output signal of the peak detector 10 and the output of the chirp oscillator 9 to judge the equal time interval during peak detection as the period of a reflected wave and calculates the frequency, and the ship speed is detected on the basis of it. Consequently, the detection speed is increased. |
