Larson Davis Spartan 821 - 2.3 Calibrating the Meter

Spartan 821/721 Manual Calibrating the Meter 12
Utilizing External Power Connections
TAKE NOTE The operating temperature range is –22 to 140 °F (–30 to 60 °C). For
additional detail, see A.1.16 Environmental Conditions Specifications
.
When utilizing the included USB-C cable with a 5V, 3A supply, the meter’s battery reaches
maximum charge in under 8 hours.
Charging via the Wireless Charging Pad
When utilizing the included universal power supply and optional wireless charging pad
(PSA046), the 721 or 821 reaches maximum charge in under 13 hours. View additional
details in A.1.10 Wireless Charger Specifications
Step 1. Rest the back case of the meter on the wireless charging pad. This positions the
meter’s internal charging coils over the pad. For the location of the internal
charging coils, review the back label of the meter.
Step 2. The wireless charging pad must be powered by the included USB cable. When
the meter is powered on and charging, the on-screen battery icon displays an
animated charging bolt (see Table 2.4
).
2.3 Calibrating the Meter
In this section:
• 2.3.1 About Acoustic Calibration
• 2.3.2 Calibrating Your Instrument
• 2.3.3 About Scheduling Factory Calibration
2.3.1 About Acoustic Calibration
In acoustic calibration, the sound level calibrator (CAL200) provides an acoustic signal of a
known amplitude (94/114 dB) and frequency (1000Hz) to the microphone which is used as
a reference to adjust the system sensitivity. In the meter, the system sensitivity updates
with each calibration.
We recommend that you calibrate prior to each measurement. Transporting or even
repositioning may introduce variations in temperature and humidity, which impact the
accuracy of the meter, microphone, and preamplifier.
When the sound level meter is not used near reference environmental conditions, then
corrections will need to be added for the ambient temperature and the prevailing static
pressure. Check the calibration data shipped from Larson Davis with the calibrator to get
corrections for the influence on the calibrator output level.
TAKE NOTE An acoustic calibrator creates an acoustic pressure field of a known
amplitude. The 377B02 and 375A04 are free field microphones, not pressure
microphones, so a small correction should be applied for the most accurate
acoustic calibration. In the calibration settings of the 821/721, adjust the output
level of the calibrator down by 0.12 dB from the level shown on the calibrator's
calibration certificate to account for this. For example, if the calibration sheet says
that the calibrator output is 114.02 dB, then the value entered into the meter for the
calibrator's output should be 113.90 dB.