Casella CEL CEL-414 - Manual (Page 48)

Microphone meets the require-
ments for both free field (IEC 651
and IEC 804) and random incidence
(ANSI Type S(1) S1.4),
Impedance to be substituted for
microphone: Not possible, use
CEL-316 Line Input Adaptor.
Correction for microphone
extension cable:
No significant effect with CEL
extension cables up to 100 m.
With other cables, or for greater
accuracy, calibrate after installation.
Verification reference conditions:
Free field perpendicular incidence,
Ambient temperature: 20
o C,
Measurement Range: 80 to 140 dB,
Relative Humidity: 65%,
Excitation SPL: 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 greater accuracy, or
temperatures outside this range but
within -10 to +50
o C use:
Corrected reading
= Instrument reading - 0.02(t - 20)
Where: t is o C.
Storage range: -20 to +60 o C.
Effect of vibration on accuracy:
Less than 6 dB when tested according
to IEC 651 clause 8.3.
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.)
Directional response:
Within the limits of IEC 651.
Effect of windshield:
Negligible on frequency response,
reduces wind induced noise typically
14 dB for wind speeds
<100 km/hour.
Effect of operator:
Negligible when microphone is
pointing away from operator
standing 2 m behind instrument.
Frequency weightings:
A-weighting to IEC 651 Type 1, (all
versions),
C-weighting to IEC 651 Type 1, (C &
D versions),
Linear (flat), (A, B & CEL-493/3),
External filter plus A-weighting (to
IEC 651 Type 1),
External filter plus linear.
Time weightings:
Fast: 125 milliseconds,
Slow: 1 second,
Impulse: 35 milliseconds risetime,
1.5 seconds decay,
Peak: <100 microseconds.
Page 44 - General CEL Sound Level Meters Handbook