Tuesday 13 July 2010

Acoustic measurements

New Endevco® Low-Profile Surface Microphone with Integral ISOTRON® Amplifier and TEDS

Meggitt Sensing Systems has announced the new market introduction of the Endevco® model EM40PS, a low-profile surface microphone with integral ISOTRON® (IEPE-type) amplifier and TEDS, designed to facilitate simplified larger channel count acoustic measurements on typical planar and curved surfaces exposed to air slipstreams.

The robust design of model EM40PS requires no microphone holders or stands, and incorporates a dust-free, water-repellant grid cap and a lightweight, detachable silicon rubber fairing, allowing for near-flush mounting on curvilinear surfaces and mounting pads. Models also include an integral 3.3 ft (1 m) coaxial cable with microdot connector. Units offer a nominal sensitivity of 5 mV/Pa (@ 250 Hz), wide audio frequency range from 20 Hz to 20 kHz and large dynamic range from <30 dBA to 136 dB over an operating temperature range of -20ºC to +80ºC (-4ºF to +176ºF) with low sensitivity to base bending. Because of its lightness, the EM40PS contributes very little mass to thin plates, and can be laid flat on its 2” (51mm) diameter rubber pad, or surface mounted using a double-sided adhesive pad for automotive, aeronautical, general acoustics and sound pressure level testing requirements. Pressure equalization is via a vent placed at the front of the microphone by the side of its diaphragm, important for both aircraft usage and on-road vehicle measurements in mountainous country. Close manufacturing tolerances and the advantages of TEDS enable the microphone to offer a high degree of interchangeability, precluding the need for accounting of individual characteristics.

Recommended accessories for the model EM40PS include the model EM42AA handheld pistonphone calibrator; the model 4416B constant-current power supply (2-20mA); and the model 133 signal conditioner. With its unique size and performance characteristics, the unit is ideal for measuring wind-induced noise on ground and airborne vehicles; acoustic radiation surface measurements; wind tunnel noise testing; and for making internal vs. external noise measurement comparisons on moving vehicles.

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