Larson Davis System 824, Reference Manual

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11/2/00 FFT (Optional) 11-5
• 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 micro-
phones. • Direct - This indicates that no microphone is being used
and electrical signals are being injected directly into the
preamplifier. No polarization voltage is generated.
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 Appendix C for the random inci-
dence correction filter’s response. No - Random incidence correction is turned off.
Yes - Random incidence correction is turned on.
NOTE: Random incidence correction can be used with the 2540
and 2541 microphones.
Linear Units
If this field is left blank then no lin-
ear value will be displayed. 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
u
and down
d
arrow keys.
Linear Scale
Allows you to enter the sensitivity of a transducer in deci-
bels relative to volts.
• -128.99 to 127.99
NOTE: See the section “Entering Linear Units” on Page 10-
12 for a more detailed explanation.