Larson Davis System 824, Reference Manual

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7-6 824 Reference Manual 11/8/00
There are certain features (such as
event counting) that function only for
one detector and one weight.
Impl
-
An impulse detector which has a very fast
rise time (a 35 mS time constant) but a very slow
decay time.
Weighting Setting - (SSA, LOG,
ISM)
Weighting - selects the desired frequency weighting for the
RMS and secondary peak detectors. The Weighting setting
provides the following three options:
A
-
The instrument uses an A-weighted input filter.
C
-
The instrument uses a C-weighted input filter.
NOTE: The -10 and -20 dB gain settings
are not available for electret or direct
transducer types (see “Transducer”).
FLT
-
The instrument uses Flat weighting (see
specifications for passband frequency in Appendix
D).
Gain Setting - (SSA)
The Gain setting is only available to
the SSA instrument. Gain - The gain setting sets the measuring range of the
instrument in 10 dB steps by adjusting the amplification of
the microphone’s signal. The lowest and highest levels that
can be measured accurately are indicated by each live dis-
play’s graph scale. this setting provides the following
options:
NOTE: If Gain is set to -10 or -20 dB
and the microphone type is not con-
denser then the gain is set to 0 dB and
the warning “Setting Conflict” is dis-
played.
-20, -10, 0, +10, +20, +30, +40, +50
Range Setting - (LOG, ISM)
The Range setting is only available
to the LOG and ISM instrument. Range selects the measurement range you desire for the
instrument. This setting provides the following three
options:
NOTE: If Range is set to “Low” and the
microphone type is not condenser then
the range is set to “Normal” and the
warning “Setting Conflict” is displayed.
Normal - The instrument’s available dynamic
range is positioned in the “normal” range which is
typically 20dB to 130 dB when using a Lar-
son•Davis high-sensitivity microphone.
Low - The instrument’s input circuitry provides an
additional 20dB of gain which has the effect of
moving the instrument’s available dynamic range
downward relative to the “normal” range. The net