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4)
To attach the single-sided adhesive pad (see Figure 8) when the Surface Microphone will
be used in moderate to heavy air flow, peel off the protective paper to expose the pad’s
adhesive surface and press it onto the Fairing as shown in Figure 5.
Figure 8: Single sided adhesive pad
4.3.
Operation
After completing the system setup, switch the signal conditioner on and allow 1 to 2 minutes for
the system to stabilize. The meter (or LED) on the signal conditioner should be reading “green”.
This indicates proper operation and you may begin taking measurements. If a faulty condition is
indicated (red or yellow reading), first check all system connections, then check the functionality
of the cable and signal conditioner. If the system still does not operate properly, consult a PCB
factory representative.
5.0
Calibration
All PCB microphones come with certificate of calibration and compliance with ISO 9001, and
ANSI/NCSL Z540.3. The microphone is traceable to one or more of the following National Labs
(NIST, PTB or DFM), and calibration records are on file. PCB utilizes the “Back-to-Back
Reference” form of calibration. The microphone is checked against a test and measurement
working standard microphone and must meet specifications before it can be shipped. An example
of the result of one of the tests is shown above.
See Figure 2.
Microphone calibration provides, with a definable degree of accuracy, the necessary link
between the physical quantity being measured and the electrical signal generated by the
microphone. In addition, other useful information concerning operational limits, physical
parameters, electrical characteristics or environmental influences may be determined. Under
normal conditions, microphones are very stable. However, the microphone may be temporarily
or permanently affected by harsh influences, such as moisture, dirt, being dropped accidentally
or other unusual conditions that may cause the microphone accuracy to deviate from the normal
specifications. This may manifest itself in a number of ways, ranging from a loss in frequency
range to total failure of the built-in microelectronic circuit due to high mechanical shock.
It is for this reason that PCB recommends that a recalibration cycle be established for each
microphone. This schedule is unique and is based upon a variety of factors, such as: extent of
use, environmental conditions, accuracy requirements, trend information obtained from previous
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