| 摘要 |
<p>PURPOSE:To enhance the discrimination capacity of a moving target and a fixed target, by combining a double frequency converting loop and a phase synchronous loop. CONSTITUTION:The outputs 55a, 55b of a second two-phase voltage control oscillator (reference signal oscillator) 58 and the output 61 of a third polarity change-over device 60 are inputted to a modulator 56 to input modulation output 57 to second and sixth mixers 32, 38 as a reference signal. The output 21 of a transmission source 20 is mixed with the output 57 by a mixer 32 to form mixed output 33 which is, in turn, mixed with the output 15 of a receiving antenna 14 in a fifth mixer 34 to form mixed output 35. This output 35 is inputted to a third intermediate-frequency amplifier 36 and the output thereof is mixed with the output by a mixer 38 to obtain the output 41 of a video amplifier 40. This output 41 is subjected to phase detection by a phase detector 44 using output 55a as a reference signal to be inputted to the oscillator 54. The output 41 is further subjected to synchronous detection by a synchronous detector 42 using output 55b as a reference signal to be inputted to a sweep oscillator 52 but, when frequency and a phase coincide, the sweeping of the oscillator 52 is stopped to hold the DC signal of output 53. By this constitution, because the amplifier 36 acts as a narrow-band Doppler gate, resolving power is high.</p> |
