Project ARTEMIS. Analysis of Transducer-Impedance Variations on the Amplifier Operation. Project ARTEMIS High-Power Acoustic Source.

摘要

The impedance which a tuned sonar transducer presents to a power amplifier may vary widely by as much as two to one. Since most amplifiers are designed to provide as much output power as is permitted by the dissipation rating of the active devices, the variation, by increasing the dissipation when an impedance reduction occurs, requires a reduction in output power to allow for the increase in dissipation, and results in poor utilization of the active devices and in lower efficiency. The expected variation in impedance of the 400 cps ARTEMIS transducer while large, is not too large to completely prohibit system operation if the maximum power output is held to 1.0 Mw per amplifier, 4.0 Mw total, particularly for the contemplated noise signals. The variation is sufficiently large to make desirable some form of compensation to reduce the amount without adversely affecting the system efficiency. Such a system is a network which is parallel tuned at a frequency above the transducer center frequency and then series tuned at the point of maximum resistance of the transducer to prevent a reduction in system efficiency.