The 1981-B combines both
digital and analog displays in a single instrument. The dual-display
capability of the 1981-B simplifies accurate data collection and
the digital display gives you the advantage of more accurate (repeatable)
readings, even for the most inexperienced users of sound-level
meters.
The 1981-B spans 30 to 120 dBA in two-switch-selectable 50-dB
ranges
Digital Display
The digital display of the 1981-B has three operating modes for
maximum ease of use in a variety of measurement situations: Continuous,
Maximum Hold, and Capture
Display.
In the Continuous mode, the digital display tracks
the reading on the analog meter. This mode is normally used for
general-purpose noise surveys, giving the user the option of reading
the measured level on either the digital or analog display.
The Capture Display mode lets you
capture and hold a reading on the digital display at any given
moment by simply pressing a button. This mode is especially useful
when you wish to measure the sound level of a specific event.
You need only press the Capture Display button
when the event occurs and the sound level will be displayed and
held constant. The level is held until you release the button
so that you have adequate time to record the reading.
In the Maximum Hold mode of operation
the digital display may be set up to update and hold the maximum
A-weighted sound level automatically during a measurement period.
This eliminates meter watching and operator interpretation of
the analog display when you wish to measure the maximum sound
level encountered. This mode is particularly significant for vehicle
pass by measurements. It permits you to measure and hold the maximum
level during the pass by and, at the same time, to observe the
sound level rise and fall on the analog meter to ascertain that
a valid measurement has been made.
Two Models
To satisfy users who must comply with either or both American
and International Standards, the 1981-B is available in two versions.
One version is supplied with a flat random-incidence response
GenRad Electret-Condenser Microphone. This model conforms to IEC
651, Type 1, and when used with either a GenRad 1986 or 1987 Sound-Level
Calibrator, it conforms to ANSI S1.4-1971 Type S1A.
The second version is supplied with a flat perpendicular-incidence
response GenRad Electret-Condenser Microphone and conforms to
IEC 651. This model is designed for use in countries where ISO
Recommendations apply.
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