9/29/09 FFT (Optional) 12-5
Transducer
When a condenser microphone is
used, the 824 requires a stabilization
time of approximately 45 seconds
before a measurement can be taken.
• Condenser - This indicates that the microphone being
used is an air condenser type and the 824 will generate
the appropriate polarization voltage.
• Electret - This indicates that the microphone being used
is an “Electret” (pre-polarized) microphone. The 824
will not generate any polarization voltage.
Gains of -20 and -10 dB are only
available for condenser
microphones.
• Direct - This indicates that no microphone is being used
and electrical signals are being injected directly into the
preamplifier. No polarization voltage is generated. This
is the choice when using an accelerometer as the
transducer
Random Correction
The Random Corr setting gives you the option of turning on
a digital filter to provide the correction necessary to provide
a random incidence response when measuring with a free-
field microphone.
See "Random Incidence Microphone
Correction" on page C-24 for the
random incidence correction filter’s
response.
No - Random incidence correction is turned off.
Ye s - Random incidence correction is turned on.
NOTE: Random incidence correction can be used with the
2540, 377B41 and 2551 microphones.
Linear Units
If this field is left blank then no
linear value will be displayed. See
the section "Displaying Amplitude in
Linear Units" on page 12-14 for
more details.
Four characters of text are provided so the user can enter the
type of units being used for the measurement. It accepts any
alphanumeric character that can be found by scrolling with
the up
uand down darrow keys.
Linear Scale
Allows you to enter the sensitivity of a transducer in
decibels relative to volts.
• -128.99 to 127.99
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