Model 820 Technical Reference Manual Introduction 1-1 CHAPTER 1 Introduction Welcome to the Larson Davis Model 820. Your new hand held Model 820 from Larson Davis is a combination Type 1 preci- sion integrating sound level meter and a statistical data logger that exceeds all worldwide accuracy requirements for the mea- surement of noise. The Model 820 measures sound with the ease of operation of a “point and shoot” sound level meter. The latest advances in surface mount technology, air condenser microphones, and internal firmware have been combined in a rugged, lightweight yet extremely versatile unit. Many sound level meters in the market can create significant measurement errors because of their limited dynamic range, pulse range, and crest factor. The Model 820 does not have these limitations. Furthermore, its internal firmware is designed to accommodate changing regulations and to overcome sound measurement problems. While the Model 820 is the size of a dosimeter, it is also a complete environmental noise monitor offering features which will ensure quality measurements for many years. We invite you to read this manual to get the most out of your new Larson Davis sound level meter. About This Manual This manual has 10 chapters and 3 appendices covering the following topics:
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Model 820 Technical Reference Manual Introduction 1-1
C H A P T E R
1 Introduction
Welcome to the Larson Davis Model 820. Your new hand held
Model 820 from Larson Davis is a combination Type 1 preci-
sion integrating sound level meter and a statistical data logger
that exceeds all worldwide accuracy requirements for the mea-
surement of noise.
The Model 820 measures sound with the ease of operation of a
“point and shoot” sound level meter. The latest advances in
surface mount technology, air condenser microphones, and
internal firmware have been combined in a rugged,
lightweight yet extremely versatile unit.
Many sound level meters in the market can create significant
measurement errors because of their limited dynamic range,
pulse range, and crest factor. The Model 820 does not have
these limitations.
Furthermore, its internal firmware is designed to
accommodate changing regulations and to overcome sound
measurement problems. While the Model 820 is the size of a
dosimeter, it is also a complete environmental noise monitor
offering features which will ensure quality measurements for
many years.
We invite you to read this manual to get the most out of your
new Larson Davis sound level meter.
About This Manual
This manual has 10 chapters and 3 appendices covering the
following topics:
1-2 About This Manual Model 820 Technical Reference Manual
� Chapter 1 - Introduction: Overview of this user manual
and the Model 820’s functions and measurement capabili-
ties.
� Chapter 2 - Overview to Model 820: Understanding the
keyboard and screen, turning the instrument on and off,
and checking the battery voltage.
� Chapter 3 - Calibration: Using a reference to calibrate the
instrument and its importance.
� Chapter 4 - Quick Start: Setting parameters, using function
keys, and using numbers and other characters.
� Chapter 5 - Performing a Measurement / Reading the
Data: taking a measurement and becoming familiar with
the function keys.
� Chapter 6 - Timed Measurement: Using the timer for unat-
tended readings, setting additional parameters, and using
the password lock.
� Chapter 7 - History Functions: Setting parameters for
exceedance levels, history, interval, time history , and daily
history.
� Chapter 8 - Parameters: A complete listing of all parame-
ter items and an explanation of their basic functions.
� Chapter 9 - Memory Usage: Sizing parameter needs to
insure adequate memory for any given measurement.
� Chapter 10 - Printing a Report: Turning gathered data into
a printed report.
� Appendix A - Specifications: A listing of acoustic, elec-
tronic, environmental, and physical characteristics of the
Model 820.
� Appendix B - Model 820 Serial Port Interface Remote Con-
trol: Setting interface commands with their syntax.
� Appendix C - Glossary: Definitions of key terms and con-
cepts used in this manual.
� Appendix D - Index: Alphabetical listing of all major com-
ponents of this manual.
Model 820 Technical Reference Manual About This Chapter 1-3
About This Chapter
Specifically, this introductory chapter covers the following
topics:
� Formatting Conventions: Explanation of the fonts and
other formatting conventions used in this manual.
� Model 820 Features: A listing of the featured characteris-
tic, and capabilities of the Model 820.
� Model 820 Components: Description and diagrams of the
Model 820 external parts.
� Getting Started: Instructions for unpacking, a listing of
accessories and optional equipment and initial setup.
Formatting Conventions
This manual uses the following formatting conventions:
Functions accessed by pressing a key on the Model 820
keypad are shown with an icon, for example:
Press e and then press c.
In step-by-step directions, the process (what you do) is shown
in the left column, and the rationale (why you do it) with other
cautions and comments are shown in the right column. For
example:
Microphone Polarization Voltage is preset by Larson Davis at
200 volts. Should this parameter be incorrect, the Model 820
will not calibrate correctly.
1-4 Formatting Conventions Model 820 Technical Reference Manual
Step 1 Check the microphone polarization. To do this turn
on the Model 820, press R, m, 4 and 3, and
e. The following display will appear:
The flashing (f), the Keyboard Sta-
tus Indicator, displays which key
functions are active. This indicates
that the function keys are used for
different purpose in current func-
tion.
Step 2 Should the brackets contain a value other than [200]
e.g. [28, 0],press ther until the value [200]
appears, and then press e.
In this screen the value [200} is
selected from three options: [200,
28, 0]
Model 820 Technical Reference Manual Features 1-5
Especially important information is shown in italics, for
example:
Features
The Larson Davis Model 820 meets the requirements of the
American National Standards Institute (ANSI) S1.4,
International Electrotechnical Commission (IEC) 651, and
804-1985 standards for Type 1 accuracy and offers the
following features:
� Dynamic range of more than 100 dB for error free mea-
surements.
� Impulse measuring range greater than 100 dB.
� Standard microphone allows measurements typically
between 30 and 140 db(A) in one range. Optional micro-
phones allow measurements as low as 20 dB or as high as
190 dB(A). Mic. bias is user selectable: 0, 28, and 200 V.
� Selectable A and C frequency weightings for hearing pro-
tector applications.
� Multiple detectors provide simultaneous RMS and PEAK
measurements.
� Leq integrated level (duration ranging from 1 second to 99