12
Functional Block Diagram
Frequency Calibration Equipment
+
Microphone
Level Calibration
Level Calibration Equ Microphone
Power, Signal Condi-
tioning, and Switching
System Controller
Sound
Source
Preamplifier 1
Off
DC
Power Supply
Microphone
Preamplifier 2
Actuator
Frequency
Stepping, e.g. 1/6 oct.
Microphone
Definition File
:
- Test Conditions
- Test Details
- Preset test
PCI Cards
Calibration
Software
Documentation
Software
Calibration
Certicate
PDF Doc.
Sensitivity @ 250 Hz
Adobe
Calibration Certificate
Auto-switching
Microphone Registration
Frequency Calibration
Hz
Microphone
Calibration File:
-
Frequency
Response
- Open-circuit
Sensitivity
@ 250 Hz
Microphone
parameters
Fig. 6.
The complete microphone calibration system represented by functional blocks
A overall functional block diagram of the 90CA has four areas as explained here.
The
Level Calibration Equipment
block covers the components needed to determine
the microphone’s open-circuit sensitivity [mV/Pa].
The
Frequency Calibration Equipment
block covers the components needed to deter-
mine the microphone’s frequency response.
The
Power, Signal Conditioning, and Switching
block covers the DC power supply,
signal conditioning, and automatic switching between level and frequency calibration.
The
System Controller
block covers the following:
• PXI cards for digital I/O and data acquisition with PXI-based system control or
equivalent PCI-cards for PCI-based system control
• Preinstalled calibration software (SW0002) specifically designed for the 90CA
• Preinstalled microphone and preamplifier definition files (described elsewhere in
this manual)
• Microphone Calibration File for the test results
• Software for generating the documentation - the calibration certificate