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4.
OPERATION
4.1. INTRODUCTION
a)
The Type 211 6 has been designed primarily as a combined Generator
I
Analyzer
I
Re-
corder with a built-in memory which is used to regulate the generator output level auto-
matically in order to provide a constant, known excitation level to which the response of
the test object can be measured. In addition, the instrument may be used without auto-
matic regulation of the output signal to supply a constant voltage to a test object, e.g.
when measuring the characteristics of telephone
I
headphone earpieces or bone vibra-
tors. It may also be used without the generator to analyze an external signal, e.g. noise
or vibration. The three basic methods of operation are shown diagrammatically in
Fig.4.1.
To make use of the internal digital memory to regulate the test environment automati-
cally, the instrument must be operated with the COMPRESSION slider switch on the rear
panel in the "In" position and a correction curve recorded first. When not using this au-
tomatic level regulation facility, the switch should be in the "Out" position
.
Regulated
Test
Measurement
Measurement
Transducer
Test
Measurement
Excitation
Object
Transducer
Object
Transducer
Source
G
M
A/
R
b)
G
M
A/
R
c)
G
M
A/
R
G
-
Generator
M
-
Memory
A/
R
- Analyzer/
Recorder
790347
Fig.
4
. 1.
The three basic methods of operation of the Type 2116
a) using internal memory to regulate test environment via the generator section
b) without using the internal memory. Generator section supplies constant voltage to test object
c) without using memory or generator section to analyze and record an external signal
4.2. CALIBRATION
16
General
Carry out all the preliminary adjustments necessary as in Section 3.
It is recommended that a calibration check is carried out before and after each period of
use. It is good practice to make a routine of calibrating each time the instrument is
switched on, and is of course a necessity if the transducer used is changed.
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