| 摘要 |
PURPOSE:To simply perform measurement at a high speed, by sending out a signal obtained by modulating a carrier on the basis of SINC function to a high frequency exciting coil and guiding a reflected wave to a phase detector and detecting a phase by a carrier signal. CONSTITUTION:The signal f0 from a high frequency oscillator 1 is sent to a modulator 2 as a carrier. The signal corresponding to SINC function from a control computer 3 is sent to the modulator 2 to modulate the carrier. The modulation signal from the modulator 2 is sent in a high frequency exciting coil 7 through a high frequency power amplifier 4 and a directional coupler 5. The high frequency exciting coil 7 is placed in a shield room 6 along with a receiving coil and preamplifier 8 and the reflected wave of the high frequency exciting coil 7 is guided to an amplifier 10 through a directional coupler 5 and a change-over device 9 and amplified to be sent to a phase detector 11. Said reflected wave receives phase detection on the basis of the signal of frequency f0 from the high frequency oscillator 1 and converted to a digital signal by an A/D converter 12 while said digital signal is sent to an operational computer 13 where Fourier transformation is performed to obtain frequency spectrum.
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