Casella CEL CEL-269 - Manual (Page 6)

Measurement ranges:
Range Frequency Display Primary Linearity
Setting Weighting Range Range IEC 651
A LO (low) A 30-100 dB 33-86 dB
A HI (high) A 65-135 dB 68-12 dB
C LO (low) C 30-100 dB 33-86 dB
C HI (high) C 65-135 dB 68-121 dB
Note: The lower reading is quoted at +10 dB
on noise floor. Upper reading allows
crest factor 5.
Directional response:
Within the limits of IEC 651.
Microphone type:
CEL quarter-inch diameter pre-polarised electret,
typically 10 mV/Pa, permanently attached to the
instrument.
The microphone meets Type 2 requirements for
both free field and random incidence
measurement.
Impedance to be substituted for micro-
phone:
Not possible, microphone permanently attached;
contact CEL for method of measuring electrical
performance.
Calibration reference conditions:
Free field perpendicular incidence,
Ambient temperature: 20 o C,
Relative humidity: 65%,
Measurement Range: HI (high),
Excitation S
PL
: 114 dB,
Frequency: 1 kHz.
Effect of humidity on accuracy:
Less than ± 0.5 dB over the range 30 to 90% RH
(provided there is no condensation), relative to the
value at 65% RH and 40 o C.
Storage range: 20 to 95% RH non-condensing.
Effect of temperature on accuracy:
Less than ± 0.5 dB over the range -10 to +40 o C.
For temperatures between +40 and +50 o C it is
recommended that the instrument be recalibrated
at the operating temperature with a CEL-282 or
CEL-284/2.
However above 40 o C, accuracy within the limits
of IEC 651 can be obtained using the following
correction, where t is o C:
Corrected reading
= display reading+ 0.05(t-40).
Operating temperature range: -10 to +50 o C.
Storage range: -20 to + 60 o C.
Effect of magnetic fields on accuracy:
Negligible at all levels.
Lower than a reading of 30 dB(A) when tested
according to IEC 651 clause 8.4.
Effect of vibration on accuracy:
Less than 3 dB when tested according to IEC 651
clause 8.3.
Effect of operator:
Negligible when instrument held at arm's length
with microphone pointing away from operator.
Frequency weightings:
A- and C-weightings according to ANSI S1.4 Type
2A, and IEC 651 Type 2.
Time weightings:
F (fast): 125 milliseconds,
S (slow): 1 second,
I (impulse): 35 millisecond rise time,
1.5 second decay time.
Digital display:
4 digits,
7 segments,
10 mm high characters,
0.1 dB resolution.
Display updated 2 times per second.
Functions indicated:
S PL : Noise levels dB(A) and dB(C),
M AX : Holds noise readings of F, S, & I, with
no decay,
L EQ : Calculated L
eq
values based on a
sampling rate of 160 samples per
second,
B ATT : Battery voltage,
Low battery level. (Indicated when
battery falls below approximately 3.2
V),
Over load,
Under range.