パラメトリック受波器実用化への問題 : 空中マイクロホンを通しての検討

抄録

A parametric receiver uses the nonlinear interaction of pump wave and incoming signal wave, and it can dispense with phasing sensors along the array. Directivity of the receiver is the same form with the line array of pump transducer-detector distance. In the present paper, SNR of the receiver is measured using 40kHz pump wave and 97cm array length in air, and causes of noise generation are discussed. Harmonic components of the pump wave are phase-modulated by signal wave in the same fasion with the pump. The fact that the harmonic parametric receiving array really exists suggests an effective way for SNR improvement. The fluctuations of parametric signals caused by a weak airflow are also investigated. It is made clear that the amplitude fluctuation suppression for the output signal of parametric receiver are very important problems in order to develop the receiver for practical use.