| 摘要 |
<p>PROBLEM TO BE SOLVED: To accurately measure an altitude of a low altitude region by detecting a beat signal from a frequency difference between a reflected wave from a ground surface transmitted to an article to be measured and a transmitted wave and detecting the altitude of a transmitting means from the ground surface based on a frequency of the beat signal. SOLUTION: A VCO(voltage controlled oscillator) 2 generates a signal SH to be modulated according to a triangular signal SC input from a VCO driver 3. A coupler 5 branches the signal SH to a circulator 6 and a mixer 7. The mixer 7 mixes an input reflection signal PH with the signal SH, and outputs a beat signal SY to an amplifier 9. The amplifier 9 outputs the beat signal SZ to a phase detector 10 and a Doppler detector 11. The detector 11 outputs a Doppler waveform signal SD to a comparator 14. An AND circuit 15 inputs a detection signal SR as a pulse. A counter 16 integrates the pulse number of the signal SR, and outputs an integrated signal SA to an altitude calculator 17.</p> |
