| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly accurate result on a real time basis without any need of a fast analog-digital converter, regarding correlation function measurements such as passive delay time measurements. SOLUTION: Two measurement signals a(t) and b(t) are limited to the prescribed measurement frequency band (center frequency: f0 , band width: BW) via conversion parts 11 and 12, and converted to the same intermediate frequency IF. Also, mixers 13 and 14, and local oscillators 15 and 16 are used for the further frequency conversion of the measurement signals a(t) and b(t), in order to generate the prescribed frequency difference, and the result so obtained is multiplied by a multiplier 18. Then, a differential frequency component is subjected to a vector detection process, thereby finding phase information P(f0 ) and amplitude information. In this case, the delay timeτΔτ(f0 ) is determined by dividing the phase information P(f0 ) by a center angle frequency 2πf0 .
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