Larson Davis System 824, Reference Manual

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9/13/00 C -11
NOTE: A-weighting, C-weighting, and
Flat are measured to ANSI S1.4 and IEC
60651 standards for SLM linearity. 1/3
octave filters listed are measured to the
IEC 61260 standard for Class 0 linearity
which is ±0.3 dB. The numbers in the
table represent SPL levels with a typical
2541 microphone which has 44.1 mV/Pa
sensitivity.
*NF is noise floor.
Measurement Range (SSA mode only)
0dB Gain 10dB Gain 20db Gain 30dB Gain 40dB Gain 50dB Gain
NF Start End
Rang
e
NF Start End
Rang
e
NF Start End
Rang
e
NF Start End
Rang
e
NF Start End
Rang
e
NF Start End
Rang
e
AW 33 48 128 80 24 38 118 80 15 28 108 80 8 23 98 75 7 20 88 68 6 20 78 58
CW 32 48 128 80 23 38 118 80 16 28 108 80 9 23 98 75 8 20 88 68 8 20 78 58
FLA 32 48 128 80 25 38 118 80 21 33 108 75 21 33 98 65 26 33 88 50 23 40 78 38
16.0 2 45 128 83 2 35 118 83 1 25 108 83 2 25 98 73 -1 28 88 60 1 23 78 55
31.5 3 43 128 85 1 35 118 83 1 23 108 85 2 25 98 73 -4 22 88 66 -4 23 78 55
63.0
4 40 128 88 0 33 118 85 1 23 108 85 0 22 98 76 -7 15 88 73 -7 18 78 60
125 2 40 128 88 -2 27 118 91 -3 28 108 80 -2 18 98 80 -9 11 88 77 -8 8 78 70
250 3 37 128 91 -3 25 118 93 -3 15 108 93 -4 15 98 83 -10 8 88 80 -9 8 78 70
500
12 33 128 95 4 25 118 93 -3 15 108 93 -4 13 98 85 -10 6 88 82 -10 8 78 70
1000 10 32 128 96 2 20 118 98 -4 15 108 93 -5 13 98 85 -10 6 88 82 -10 8 78 70
2000 15 32 128 96 6 20 118 98 -2 15 108 93 -5 13 98 85 -8 8 88 80 -8 8 78 70
4000 14 32 128 96 7 20 118 98 0 15 108 93 -2 13 98 85 -6 8 88 78 -6 8 78 70
8000 14 32 128 96 7 20 118 98 1 15 108 93 -1 13 98 85 -2 12 88 76 -3 13 78 65
AUD Mode Specifications
AC/DC output: For AUD, AC and DC
outputs are undefined.
Pulse mode: The pulse test output is
computed from a Dis-
crete Hilbert Transform
which is sampled every
½ millisecond. The Dis-
crete Hilbert Transform
produces a mathemati-
cally correct sample of
the input waveform
envelope.
Time resolution: 0.5 ms to 1.0 seconds
in 0.5 ms increments
Time accuracy: ±1.0 ms
Hilbert transform mag-
nitude error: < 0.1 dB
Dynamic range: > 80 dB
Hilbert transform Sam-
ple rate: 2000 Hz
On level computation: After the “ON” state has
been detected, the
“ON” level is computed
as the average of 32
samples.