Accession Number:

ADD014514

Title:

System for Detection of Transducer Defects.

Descriptive Note:

Patent, Filed 30 Sep 82, patented 1 May 84,

Corporate Author:

DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s):

Report Date:

1984-05-01

Pagination or Media Count:

6.0

Abstract:

Apparatus and method for nondestructive detection of loose parts or faulty bonds in sound transducers by measuring erratic second-order nonlinear difference-frequency responses of the test transducer to a pulsed high level dual-frequency sound field produced by a high power projector. Such field may be generated by combining a high frequency carrier signal at frequency fo with a low frequency tone burst signal at frequency f2 in a double balanced modulator so as to produce the dual-frequency pulse at fof2 and fo-f2. The test transducer converts the dual-frequency pulse into a plurality of linear and nonlinear frequency components including the difference-frequency f. These are then fed through a passive low-pass filter to eliminate the high frequency components, amplified by a pre-amplifier, further filtered by a bandpass filter to eliminate the DC component, leaving only the difference-frequency f which is amplified by a post-amplifier and displayed on a cathode-ray oscilloscope triggered by synchronizing pulses from the tone burst oscillator. Rapid variations in the difference-frequency signal level and phase indicate a loose part or bond. US-PAT-73-1. jes

Subject Categories:

  • Electrical and Electronic Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE