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
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