Calibration

When recording or analysing any signal it is necessary to calibrate the system with a known signal.

Acoustic Calibrator

A device which produces a known sound pressure on the microphone of a sound level measurement system, and is used to adjust the system to Standard specifications. The standard acoustic calibrator produces a pure tone of 94dB at 1kHz. This is useful in that A, B and C weighting networks give zero attenuation at 1kHz. A pistonphone is useful when wanting to calibrate at a larger sound pressure level, typically 124dB. However, the standard pistonphone produces a pure tone at 250Hz and so the level will be affected by the weighting networks.

Shunt Calibration

Shunt calibration is a method of simulating a known value of the measurand for bridge-type transducers.

A fixed value resistor is connected across one or more arms of the Wheatstone bridge. This produces a known output from the bridge, and is used for verifying the accuracy of the data acquisition system, including the excitation supply, amplifier and acquisition system.