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) : Moffett, Mark B ; Konrad, William L

Report Date : 01 May 1984

Pagination or Media Count : 6

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 f/2 in a double balanced modulator so as to produce the dual-frequency pulse at fo+f/2 and fo-f/2. 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)

Descriptors :   *TRANSDUCERS, BANDPASS FILTERS, CARRIER FREQUENCIES, CATHODE RAY TUBES, DEFECTS(MATERIALS), DETECTION, DIFFERENCE FREQUENCY, DIRECT CURRENT, DUAL MODE, FREQUENCY, HIGH FREQUENCY, HIGH POWER, LINEARITY, LOW PASS FILTERS, MODULATORS, NONDESTRUCTIVE TESTING, NONLINEAR SYSTEMS, OSCILLOSCOPES, PARTS, PASSIVE SYSTEMS, PULSES, RADIO SIGNALS, RADIOFREQUENCY, SIGNALS, SOUND, SYNCHRONIZATION(ELECTRONICS), TEST AND EVALUATION

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE