IMS 3638 Manual Del Usario página 28

24 Exhaust Noise Inspector Type 3638 – User Manual
Calibration
Calibration is an adjustment of your instrument to ensure correct measurement and display
values. This is necessary because the sensitivity of the microphone and the response of the
electronic circuitry can vary slightly over time or could be affected by environmental conditions
such as temperature and humidity. Often calibration is required by national and international
measurement standards before each set of measurements. Most standards for stationary vehicle
noise measurement require calibration of the sound level meter only.
Sound level meter calibration is performed using the supplied Sound Level Calibrator Type
1
4231 . It provides a stable sound pressure at 1 kHz and has minimal susceptibility to environ-
mental factors. You use the calibrator's reference signal at 1 kHz to compare and adjust your
sound level meter in full, including microphone, preamplifier and electronic circuitry.
The procedure for calibration is simple:
1) Stand away from loud sound sources that may interfere with the calibrator's signal.
2) Without removing Sound Level Calibrator Type 4231 from its slot in the carrying case, fit
the microphone carefully into the calibrator as shown in Fig.4.1 below.
Fig.4.1
Sound Level Calibrator
Type 4231 fitted onto your
sound level meter
Ensure that the calibrator fits snugly on the microphone.
3) Press on the sound level meter to display the calibration window. With Mediator Type
2238 (the supplied sound level meter with Type 3638 A), pressing the Calibrate key will
take you to a Calibration menu. Press
Fig.4.2 shows examples of the Calibration Window.
1Sound Level Calibrator Type 4231 is supplied with Exhaust Noise Inspector Type 3638 A. Type 3638 B's
carrying case includes a foam compartment for the calibrator, which is purchased separately.
to select Calibration and to confirm.