| 摘要 |
PURPOSE:To execute Doppler detection with respect to a signal which has been brought to frequency modulation in a short time and with high accuracy, by synthesizing a frequency step signal which is varied stepwise, making it uniform in terms of frequency and time and inputting it to a PLL circuit. CONSTITUTION:A frequency modulated wave receiving signal 1a whose frequency is varied stepwise at every prescribed step time is converted to reference frequency signals 5b-8b higher than an input signal by frequency converting circuits 5-8 corresponding to each frequency. The converted signals are adjusted so as to be outputted by the same timing by delaying circuits 13-15 through BPFs 9-12, and thereafter, added by an adder 19. The added reference frequency component and a Dopper frequency component are inputted to a PLL circuit 2 synchronizing with said reference frequency. A lock voltage outputted from the PLL circuit is brought to frequency conversion by a voltage - frequency converting circuit, and outputted as a Doppler frequency.
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