14
System Controller
The system controller has PXI or PCI cards and software preinstalled.
• Control Card:
National Instruments Digital I/O PXI-6509 (PCI 6503), Input/
Output Module (A/D Conversion); controls the signal switching between level and
frequency calibration.
• Data Acquisition Card:
National Instruments Dynamic Signal Acquisition Board
PXI-4461 (PCI 4461) with 24-bit analog inputs and outputs and a sampling rate
of 204.8 kS/s.
• Microphone Calibration Software
• Microphone Definition File:
For level calibration, this input file contains
- test parameters such as pistonphone level and frequency
- test specifications for the microphone (microphone sensitivity [max; min]).
• Microphone Calibration File:
For level calibration, this output file contains:
- the microphone’s open-circuit sensitivity in [dB re. 1 V/Pa] and [mV/Pa]
- “Pass” / “Fail” indication
Hardware and Software for Frequency Calibration
Actuator Supply
14AA
.
Electrostatic Actuator
RA0014
Adapter
Actuator
Calibration Stand
AL0010
Preamplifier
26AB
(inside
calibration
stand)
G.R.A.S.
¼
”
-
½
”
A
dapter
AF
0
0
0
8
Po we r
G.R.A.S.
Actuator Supply
Type 14AA
AC Output
+20 0VD C
AC Output
Max. 1Vrm s
+80 0VD C
AC Output
On
GND
AC Input
Overload
G.R
.A.S
.
R
A 0 014
PXI Cards
Control
Card
NI6503
Calibration
Software
SW0002
Control
Card
Data Acqui-
sition Card
Microphone
Definition File
Frequency Response
- Test frequencies
(1/6 octave stepping)
- [Max;min] for each
test frequency
Microphone
Calibration File
Output for
Frequency Response:
- Level (magnitude [Pa]
and phase)
- Pass/Fail indication
Microphone
for calibration
Frequency Calibration Equipment
Power Module
Control
Box
G.R.A.S.
RA0192
Active
Actuator
Stand
Polarization
Preamp.
phone
Insert
Piston-
Extended
Range
Frequency
Preamp.
Test
Input
Preamp.
Preamp.
Input Adapter
Signature Series
20
-20
-10
70
-20
30
Overload
Gain in dB
G.R.A.S.
Power Module
Filter
Latch
Overload
Channel 1
Channel 2
Polarization 0V
Preamp. ±15V
Type 12AQ
Remote
Battery
Power
40
10
0
50
60
Ext
Lin
HP
AW
Lin
Ext
Filter
HP
AW
CCP Input
Floating Output
SysCheck
50
60
70
50
60
40
20
30
10
0
-10
Gain in dB
Signal Conditioning
System Controller
Fig. 8.
Functional block diagram of the 90CA hardware and software for frequency calibration
The block diagram for frequency calibration is similar to the diagram for level calibration.
The details are the same for the system controller and the power, signal conditioning,
and switching. The equipment block is different.