SV 33A USER MANUAL
.
3
As indicated in Table 1, an acoustic calibrator has significantly lower tolerance
than a sound level meter of the same class. Intuitively, we understand, that
the calibrator, as a reference for acoustic pressure must be more precise than
a measurement device.
Taking acoustic measurements according to norms and standards imposes
the requirement of calibrating the measurement channel before each measurement
or measurement session and very often as well after the measurement for result
verification purposes.
2. Acoustic calibrator SV 33A
2.1. General description
The SV 33A acoustic calibrator is a small, portable one-range Class 1 device
(sound source), see Picture 1. Powered by two LR03/AAA batteries, it contains
a loudspeaker producing acoustic pressure, reference microphone for monitoring
generated level, pressure and temperature sensors for measurements
of atmospheric conditions and a microprocessor system controlling the operation
of the calibrator. Sinusoidal waveform of 1 kHz frequency is digitally generated
and feeds the loudspeaker. Sampled signal from the reference microphone indicates
the level of currently generated signal in a feedback loop. On the basis
of information about the level of the signal, actual values of pressure and
temperature, microprocessor adjusts amplification of the loudspeaker signal in order
to produce appropriate sound pressure level in the calibrator’s chamber.
Due to the feedback regulation loop the SV 33A calibrator does not require
adjusting and operates in a wide range of temperature, pressure and humidity (see
SV 33A Datasheet).
Picture 1. Acoustic calibrator SV 33A
