IMPROVEMENT OF SRL GROUND MICROPHONES AND ASSOCIATED ACTIVITIES IN CONNECTION WITH DEVELOPMENT OF AN IMPROVED ACOUSTIC DETECTION SYSTEM
TEXAS WESTERN COLL EL PASO SCHELLENGER RESEARCH LABS
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A capacitor microphone was tested with tempera ture, humidity and pressure effects considered. Improvements stemmed from increased demand upon its characteristics and from inadequacies found during initial field use. An important area studied was a reasonably accurate method of checking the sensitivity calibration of the microphone. Ideally, it should require minimum equipment, be inexpensive, and be accurate within reason. Temperature, humidity, and pressure altitude effects on various methods were studied. The calibration described provides a good compromise among the above factors. Atmos pheric effects either do not become a considera tion or they can be correlated directly to a correction factor. Considerable test and com parison data was obtained on the Mark II Micro barograph. It was convenient to give this micro phone the same tests as the capacitor microphone and the results were informative. Several alter nate methods of signal handling were considered. The most promising three were an FM system, a Pulse Deviation Modulation PDM system and a BrT system. Sufficient sensitivity could be obtained from each if a suitable, inexpensive detector system could be developed.
- Acoustic Detection and Detectors