Larson Davis System 824 User manual

System 824
Reference Manual
Larson Davis Inc.
1681 West 820 North
Provo, UT 84601-1341
Phone: [phone]
FAX: [phone]
www.larsondavis.com
I824.01 Rev. g

824 Reference Manual
ii
Copyright
Copyright 2000 by Larson Davis, Incorporated. This manual and the software described in it are copy-
righted, with all rights reserved. The software may not be copied in whole or in part for commercial
use without prior written consent of Larson Davis Inc. The manual may not be copied in whole or in
part for any use without prior written consent of Larson Davis Inc.
Disclaimer
The following paragraph does not apply in any state or country where such statements are not agree-
able with local law:
Even though Larson Davis, Inc. has tested the software and reviewed its documentation, Larson Davis
Incorporated makes no warranty or representation, either expressed or implied, with respect to this
software and documentation, its quality, performance, merchantability, or fitness for a particular pur-
pose. This documentation is subject to change without notice, and should not be construed as a com-
mitment or representation by Larson•Davis Inc.
This publication may contain inaccuracies or typographical errors. Larson Davis Inc. will periodically
update the material for inclusion in new editions. Changes and improvements to the information
described in this manual may be made at any time.
Warranty
Larson Davis warrants this product to be free from defects in material and workmanship for two years
from the date of the original purchase. During the two year warranty period, Larson Davis will repair
or, at its option, replace any defective component(s) without charge for parts or labor if the unit is
returned, freight prepaid, to an authorized service center. The product will be returned freight prepaid.
Product defects caused by misuse, accidents, or user modification are not covered by this warranty.
The warranties described above are exclusive and in lieu of all other warranties whether statutory,
express or implied including, but not limited to, any implied warranty of merchantability or fitness for
a particular purpose and all waranties arising from the course of dealing of usage or trade. The buyer’s
sole and exclusive remedy is for repair or replacement of non-conforming product or part thereof, or
refund of the purchase price, but in no event shall Larson Davis ( its contractors or suppliers of any
special indirect, incidental, or consequential damages) whether the claims are based in contract, in tort
(including negligence), or otherwise with respect to or arising out of the product furnished hereunder.
Representation and warranties made by any person, including its authorized dealers, representatives,
and employees of Larson Davis which alter or are in addition to the terms of this warranty shall not be
binding upon Larson Davis unless in writing and signed by one of its officers.
Larson Davis is an equal opportunity employer and does not discriminate on the basis of race, color,
religion, gender, national origin, disability or veteran status.

824ReferenceManual
iii
Please examine your instrument and record the following information below. You may be asked to
give this information in any future communications you have with Larson Davis, Inc.
Record of Serial Number and Purchase Date
PRM902 Pre-amp. Serial #: ______________
Microphone Serial # ____________________
System 824 Serial #: _____________________
Microphone Model #: ___________________ Purchase Date: _________________________

824 Reference Manual
iv

824ReferenceManual
i
Table of Contents
Chapter 1 Introduction 1-1
About This Manual.................................................................................................1-1
About This Chapter.................................................................................................1-3
Formatting Conventions .........................................................................................1-3
Features...................................................................................................................1-4
System 824 Components....................................................................................1-7
System Diagram...............................................................................................1-10
Getting Started......................................................................................................1-10
Unpacking and Inspection................................................................................1-12
Accessories and Optional Equipment ..............................................................1-12
Connecting Internal or External Power............................................................1-13
Using the NiMH Battery Pack ....................................................................1-14
Using Alkaline Batteries .............................................................................1-14
Using the AC Power Adapter......................................................................1-15
Chapter 2 Overview 2-1
System 824 Setups or Instrument Definitions ........................................................2-1
Instrument Definition (ID) Types ..........................................................................2-2
SLM&RTA (SSA) .............................................................................................2-2
SLM (ISM) ........................................................................................................2-4
Logging (LOG)..................................................................................................2-4
Selecting a Measurement Setup..............................................................................2-5
Performing a Measurement; SLM&RTA (SSA) example......................................2-6
Stop, Pause and Back Erase Functions ..............................................................2-7
Stopping and Starting Measurements............................................................2-7
Pausing Measurements..................................................................................2-7
Back Erasing .................................................................................................2-8
Changing the detector of the displayed SPL value ............................................2-8
Changing the frequency weighting of the displayed SPL value........................2-9
Changing the displayed secondary parameter....................................................2-9
Changing the frequency weighting of the displayed Lpeak value...................2-10
Changing the amplitude range, or input Gain..................................................2-10
Views ....................................................................................................................2-11
Selecting a VIEW.............................................................................................2-11
Data Storage and Recall........................................................................................2-13

824 Reference Manual
ii
Storing Data.................................................................................................2-13
Recalling Data.............................................................................................2-13
Calibration ............................................................................................................2-14
Chapter 3 Front Panel Keys; their Functions and Menus 3-1

Power Key.........................................................................................................3-3
Power-up the Instrument / Viewing PWR Display............................................3-4
Power Settings....................................................................................................3-6
Extra Notes on Power Conservation..................................................................3-8

Run/Stop Key....................................................................................................3-9

Reset Key ..........................................................................................................3-9

Pause Key........................................................................................................3-10
Pause............................................................................................................3-10
Pause, Back Erase .......................................................................................3-10
Preview........................................................................................................3-11

Arrow Keys.................................................................................3-11

Check Key........................................................................................................3-12

View Key.........................................................................................................3-12

Data Key..........................................................................................................3-13

Setup Key ........................................................................................................3-14
Save ID........................................................................................................3-16
Title .............................................................................................................3-16
ID Name......................................................................................................3-16
Write Protect, Delete, Write Enable IDs..........................................................3-16

Tools Key.........................................................................................................3-17
About................................................................................................................3-19
Calibration........................................................................................................3-22
Clock/Timer .....................................................................................................3-23
Memory............................................................................................................3-27
Deleting Stored Data........................................................................................3-28
Delete Last Function ...................................................................................3-28
824 Memory Structure ................................................................................3-29
Deleting the Last Stored Record .................................................................3-29
Deleting Individual Records........................................................................3-31
Power Monitor .................................................................................................3-32
Communication................................................................................................3-33

Print Key..........................................................................................................3-36

824ReferenceManual
iii
Chapter 4 Quick Start 4-1
Turning On and Calibrating the System 824 ..........................................................4-1
Taking Measurements and Storing Data.................................................................4-3
SLM&RTA Measurements................................................................................4-3
Viewing RTA Displays during a Measurement.................................................4-6
Recalling Stored Data .............................................................................................4-8
Selecting and Modifying Instrument Definitions (IDs)........................................4-10
The Setup Menu...............................................................................................4-11
The Active ID...................................................................................................4-11
Menu Scrolling.................................................................................................4-12
Permanent IDs..................................................................................................4-13
Write-protected IDs..........................................................................................4-13
Preparing for a Measurement...........................................................................4-14
Selecting a Different ID...................................................................................4-14
Accessing the Settings Menu...........................................................................4-14
Accessing the Settings Menu to Initiate Editing or Modification....................4-16
Setting Control in the SLM View....................................................................4-19
Chapter 5 System 824 Virtual Instruments 5-1
System 824 Virtual Instruments .............................................................................5-1
Selecting an Instrument ID .....................................................................................5-3
Combined SLM&RTA ...........................................................................................5-3
SSA Measuring Ranges .....................................................................................5-4
AC/DC Output ...................................................................................................5-5
Logging SLM..........................................................................................................5-6
Time History......................................................................................................5-7
Interval History ..................................................................................................5-7
Exceedances.......................................................................................................5-7
LN Percentiles (Broadband)...............................................................................5-8
LN Percentiles (Spectral)...................................................................................5-8
Sound Exposure .................................................................................................5-9
LOG and ISM Measuring Ranges......................................................................5-9
Chapter 6 System 824 Views 6-1
Status Icons and Indicators .....................................................................................6-2
General Views.........................................................................................................6-4
SLM Views ........................................................................................................6-4
Any Data View...................................................................................................6-7
Any Level Format .........................................................................................6-7

824 Reference Manual
iv
Any Impulse Format......................................................................................6-8
Any Time Format..........................................................................................6-8
SSA Specific Views................................................................................................6-9
SSA Displays ...................................................................................................6-11
RTA Displays..............................................................................................6-11
Tabular RTA Views....................................................................................6-11
Time History Displays ................................................................................6-12
SSA Time History.......................................................................................6-16
Run Log.......................................................................................................6-19
Ln Centiles ..................................................................................................6-19
Logging SLM Specific Views ..............................................................................6-23
Current SLM and Overall SLM Views............................................................6-25
Current SLM/Overall SLM Display-a (SPL)..............................................6-26
Current/Overall SLM Display-b (Times)....................................................6-28
Current/Overall SLM Display-c (Min/Max)...............................................6-29
Current/Overall SLM Display-d (Peaks).....................................................6-29
Current/Overall SLM Display-e (TWA).....................................................6-30
Exposure Views ...............................................................................................6-31
Exposure Display-a.....................................................................................6-31
Exposure-b Display.....................................................................................6-33
Exposure-c Display .....................................................................................6-34
Ln Centiles Views............................................................................................6-35
Ln-a Display................................................................................................6-35
Ln-b Display................................................................................................6-36
Stats Views.......................................................................................................6-37
Stats-a Display.............................................................................................6-37
Stats-b Display ............................................................................................6-38
Stats-c Display.............................................................................................6-39
Run Log (LOG & SSA) ...................................................................................6-40
Time History....................................................................................................6-41
Intervals............................................................................................................6-43
Intervals-a Display ......................................................................................6-43
Intervals-b Display......................................................................................6-44
Intervals-c Display ......................................................................................6-46
Intervals-d Display......................................................................................6-47
Intervals-e Display ......................................................................................6-48
Exceedance History..........................................................................................6-49
Excd-a Display............................................................................................6-49

824ReferenceManual
v
Excd-b Display............................................................................................6-50
Excd Time History Display.........................................................................6-51
Daily Views......................................................................................................6-53
Daily-a Display ...........................................................................................6-53
Daily-b Display ...........................................................................................6-55
Hourly Leq Display.....................................................................................6-56
Metrics .............................................................................................................6-57
Metrics-a Display........................................................................................6-57
Metrics-b Display........................................................................................6-58
PassBy..............................................................................................................6-59
Chapter 7 Using ID Setting Files 7-1
Recalling ID Setting Files.......................................................................................7-1
Customizing Settings..............................................................................................7-2
Settings Example - SLM&RTA (SSA)..............................................................7-2
Settings Descriptions ..............................................................................................7-4
Common SLM Settings......................................................................................7-5
Title Setting - (SSA, LOG, ISM)..................................................................7-5
Detector Setting - (SSA, LOG, ISM)............................................................7-5
Weighting Setting - (SSA, LOG, ISM).........................................................7-6
Gain Setting - (SSA) .....................................................................................7-6
Range Setting - (LOG, ISM).........................................................................7-6
Transducer Setting - (SSA, LOG, ISM)........................................................7-7
Random Incidence Microphone Correction - ...............................................7-8
Pk Weighting - (SSA, LOG, ISM)................................................................7-8
RTA Detector Setting - (SSA) ......................................................................7-8
RTA Weighting - (SSA)................................................................................ 7-9
Bandwidth Setting - (SSA)............................................................................7-9
Common Control Settings..................................................................................7-9
AC/DC Output Settings - (SSA, LOG, ISM)..............................................7-11
Logic Input Setting - (SSA, LOG, ISM).....................................................7-11
Logic Output Setting - (SSA, LOG, ISM)..................................................7-11
Logic Output Time Setting - (SSA, LOG, ISM).........................................7-13
Logic Output #2 ..........................................................................................7-14
Logic Output #2 Time Setting.....................................................................7-14
Heater On ....................................................................................................7-14
E. A. Cal Tone.............................................................................................7-14
Logging SLM TWA Settings...........................................................................7-15
Ovll Exchange - (LOG)...............................................................................7-15

824 Reference Manual
vi
Ovll Threshold - (LOG) ..............................................................................7-16
Ovll Criterion - (LOG)................................................................................7-16
Criterion Time - (LOG)...............................................................................7-17
Crnt Exchange - (SSA, ISM, LOG)............................................................7-17
Crnt Threshold (SSA, ISM, LOG)..............................................................7-18
Crnt Criterion (LOG) ..................................................................................7-18
LOG and SSA Ln Settings...............................................................................7-18
Enable Ln ....................................................................................................7-19
Start Level...................................................................................................7-19
Ln’s .............................................................................................................7-20
Spectral Ln’s (SSA only) ............................................................................7-20
LOG and SSA Triggering Settings ..................................................................7-21
SPL Excd Lvl 1 - (LOG, SSA)....................................................................7-21
SPL Excd Lvl 2 - (LOG, SSA)....................................................................7-21
PK Excd Lvl 1 - (LOG, SSA) .....................................................................7-22
Pk Excd Lvl 2 - (LOG, SSA) ......................................................................7-22
Hysteresis - (LOG, SSA).............................................................................7-22
LOG and SSA Time History Settings..............................................................7-23
Hist Enable - (LOG, SSA)...........................................................................7-25
Hist Period (LOG, SSA)..............................................................................7-25
Period Units - (LOG, SSA) .........................................................................7-25
Other Level - (LOG only) ...........................................................................7-26
Resolution - (LOG, SSA)............................................................................7-27
Advanced Time History - (LOG, SSA).......................................................7-27
Marker Text - (LOG, SSA) .........................................................................7-28
LOG and SSA Interval Settings.......................................................................7-28
Intv Enable - (LOG, SSA)...........................................................................7-29
Intv Period - (LOG, SSA) ...........................................................................7-29
Intv Time Sync - (LOG, SSA) ....................................................................7-30
Intv Save Ln’s - (LOG, SSA)......................................................................7-30
Intv Auto Stop - (LOG, SSA)......................................................................7-30
Intv Threshold - (LOG, SSA)......................................................................7-31
Intv Exchange - (LOG, SSA)......................................................................7-31
Intv Spectrum - (SSA only).........................................................................7-32
Logging SLM Exceedance History Settings....................................................7-32
Triggering - (LOG)......................................................................................7-32
Excd Enable - (LOG) ..................................................................................7-32
Min Duration - (LOG).................................................................................7-32

824ReferenceManual
vii
Excd Time Hist - (LOG) .............................................................................7-33
T.H. Period - (LOG)....................................................................................7-33
Excd Trigger - (LOG) .................................................................................7-33
Excd Time - (LOG).....................................................................................7-33
Logging SLM Daily History Settings..............................................................7-34
Daily Enable - (LOG)..................................................................................7-34
Daily Ln’s - (LOG) .....................................................................................7-34
Logging SLM Define Report Settings .............................................................7-34
Data Report - (LOG, SSA)..........................................................................7-35
Setup Report - (LOG, SSA) ........................................................................7-35
SPL Histogram - (LOG)..............................................................................7-36
Pk-1 Histogram - (LOG) .............................................................................7-36
Pk-2 Histogram - (LOG) .............................................................................7-36
Intv Report - (LOG, SSA)...........................................................................7-36
Hist Report - (LOG, SSA)...........................................................................7-37
Menu Layout of SSA Settings ..............................................................................7-37
Menu Layout of Integrating SLM (ISM) Settings................................................7-43
Menu Layout of Logging SLM Settings...............................................................7-46
Check Menus ........................................................................................................7-52
Check Menu Example......................................................................................7-53
SLM Check Menu Options (SSA and LOG) ...................................................7-55
Mark Display...............................................................................................7-55
Graph Menu.................................................................................................7-57
Settings........................................................................................................7-58
Controls Settings Menu...............................................................................7-58
Other SSA Check Menus.................................................................................7-58
Any Data Check Menu................................................................................7-58
RTA Check Menu.......................................................................................7-59
Intervals Check Menu .................................................................................7-60
Time History Check Menu..........................................................................7-61
Run Log Check Menu.................................................................................7-62
Ln Centiles Check Menus ...........................................................................7-63
Other Logging (LOG) Check Menus...............................................................7-66
Any Data Check Menu................................................................................7-66
Current SLM / Overall SLM Check Menu..................................................7-66
Exposure Check Menu................................................................................7-66
LN Centiles Check Menu............................................................................7-67
Stats Check Menu........................................................................................7-68

824 Reference Manual
viii
Run Log Check Menu.................................................................................7-68
Time History Check Menu..........................................................................7-69
Intervals Check Menu .................................................................................7-69
Excd History Check Menu..........................................................................7-70
Daily History Check Menu .........................................................................7-71
Chapter 8 Printing a Report 8-1
Connecting the 824 to a Serial Printer....................................................................8-1
Printing Reports......................................................................................................8-2
Defining and Printing Tailored Reports..................................................................8-5
Using the Recall Format (SSA and LOG instruments only)..............................8-7
Default Settings Values for the Recall Format Reports................................8-8
Printing a Custom Report .....................................................................................8-22
Chapter 9 Using the 824 Utility Software 9-1
824 Utility Software Overview...............................................................................9-1
824 Utility Installation............................................................................................9-1
Starting the 824 Utility Software............................................................................9-2
Connecting the 824 to Your Computer...................................................................9-2
824 Utility Tool Bar................................................................................................9-4
824 Utility Setup Window ......................................................................................9-6
Retrieving setups from the 824 ..........................................................................9-7
Modifying and Storing Setups to the 824 ..........................................................9-9
Manipulating a Setup ..................................................................................9-10
Saving Setups to Disk Files .............................................................................9-12
Opening Setup Disk Files ................................................................................9-12
Creating a New Setup ......................................................................................9-14
Renaming an Existing Setup............................................................................9-15
Deleting an Existing Setup...............................................................................9-16
Locking and Unlocking Setups........................................................................9-17
Downloading Measurement Data .........................................................................9-17
Specifying a Destination File...........................................................................9-18
Changing the Download File Name.................................................................9-20
Adding Notes to a download file .....................................................................9-21
Selecting Active Measurements or Data Files.................................................9-21
Downloading the measurement........................................................................9-22
Explanation of files in the 824 Utility Directory .............................................9-24
Translating Measurement Data from a Downloaded Binary File.........................9-25
Selecting a Data set to view.............................................................................9-27

824ReferenceManual
ix
Printing a Translated File.................................................................................9-29
Viewing a Translated File Within a Spreadsheet Program..............................9-31
Additional Features...............................................................................................9-32
Chapter 10 RTA (optional) 10-1
Settings Menu .......................................................................................................10-2
Settings Descriptions ............................................................................................10-5
RTA Settings Menu .........................................................................................10-5
Autostore Settings Menu..................................................................................10-7
Arm Settings Menu..........................................................................................10-8
Trigger Settings Menu ...................................................................................10-10
End Settings Menu.........................................................................................10-11
Then Settings Menu .......................................................................................10-12
Trigger Settings Menu (continued)................................................................10-13
RTA Settings..................................................................................................10-15
RT60-A and RT60-B Instrument Definition..................................................10-16
Rooms RTA Instrument Definition................................................................10-17
Display Views.....................................................................................................10-18
RTA Views ....................................................................................................10-18
Trigger Views ................................................................................................10-22
Autostore Views.............................................................................................10-25
Autostore ByTime Spectral History...............................................................10-29
ByTime Spectrum Check Menu.....................................................................10-30
ByTime Graph Check Menu..........................................................................10-31
RT-60 .............................................................................................................10-33
RT60 Check Menu.........................................................................................10-35
Spatial Avg Views .........................................................................................10-35
Spatial Avg Check Menu...............................................................................10-37
Avg History Check Menu ..............................................................................10-38
Rooms Views.................................................................................................10-39
Chapter 11 FFT (Optional) 11-1
Features.................................................................................................................11-1
Settings Menu .......................................................................................................11-1
Settings Descriptions ............................................................................................11-3
FFT Display..........................................................................................................11-6
FFT...................................................................................................................11-6
FFT Check Menu.............................................................................................11-8
THD (Total Harmonic Distortion)........................................................................11-8

824 Reference Manual
x
THD Check Menu..........................................................................................11-10
Snapshot..............................................................................................................11-11
Snapshot Check Menu ...................................................................................11-11
Entering Linear Units..........................................................................................11-12
Chapter 12 AUD (Optional) 12-1
Selecting the 824-AUD Operation Mode .............................................................12-2
SLM+RTA Mode..................................................................................................12-3
SLM+RTA Live screen....................................................................................12-3
Any Level-a Screen..........................................................................................12-4
FFT Mode .............................................................................................................12-5
FFT Screen.......................................................................................................12-5
THD (Total Harmonic Distortion)...................................................................12-6
Linearity...........................................................................................................12-9
Pulse/FM Mode...................................................................................................12-11
Pulse/FM-a Screen.........................................................................................12-11
Pulse/FM-b Screen.........................................................................................12-14
Pulse/FM Check Menu...................................................................................12-15
Appendix A Integrated Level Calculations A-1
Basic Integrated Level Calculations ......................................................................A-1
Appendix B Serial Port Interface Remote Control B-1
Interface Cables .....................................................................................................B-2
Connection to a computer using CBL006....................................................B-2
Daisy Chain Addressing ........................................................................................B-3
824 Network, Addressing Commands ..............................................................B-3
Commands .............................................................................................................B-5
Remote Control Commands (Detailed) .................................................................B-6
Mode Commands..............................................................................................B-6
“Read” Commands (Reads out data variables).................................................B-7
“ANY DATA” READ COMMANDS............................................................B-21
Other Read Commands ...................................................................................B-23
Group Read Programming..............................................................................B-23
Setting Commands...............................................................................................B-24
Querying Settings............................................................................................B-25
Ln Query Commands (SSA)...........................................................................B-26
Entering Settings.............................................................................................B-26
Option Settings...........................................................................................B-26

824ReferenceManual
xi
Numeric Settings........................................................................................B-28
Character String Settings............................................................................B-28
Template Settings.......................................................................................B-28
Setting List...........................................................................................................B-29
Histogram Reports ..........................................................................................B-36
Tailored Report ..........................................................................................B-37
Miscellaneous.............................................................................................B-37
Error Checking I/O .........................................................................................B-40
RTA Settings Commands................................................................................B-42
History Records...............................................................................................B-45
Types of History.........................................................................................B-46
Advance......................................................................................................B-46
Backup........................................................................................................B-46
Find.............................................................................................................B-47
History Data Variables.........................................................................................B-47
Exceedance History Variables ........................................................................B-47
Interval History Variables (“I” Commands)...................................................B-49
Daily History Variables - (D1-D102) ............................................................B-54
Run Log Variables (SSA, ISM, LOG, TAL)..................................................B-56
Calibration History Variables (LOG) .............................................................B-56
Time History Variables (SSA, LOG, TAL) ...................................................B-57
Time History Variables (SSA, LOG, TAL)....................................................B-58
Histogram Table Variables .............................................................................B-58
Print Commands ..................................................................................................B-59
Error Messages and Warnings.............................................................................B-61
Modem Control Mode (All Instruments).............................................................B-64
Modem Mode..................................................................................................B-64
Dial Out Mode ................................................................................................B-64
Monitor Number .............................................................................................B-65
824 Phone Dialing Procedure .........................................................................B-65
Model 824 Answering Procedure ...................................................................B-66
Unsupported Miscellaneous Commands .............................................................B-67
Data File Commands ...........................................................................................B-68
Keyboard Simulation...........................................................................................B-69
Operation Notes...................................................................................................B-70
Appendix C Technical Specifications C-1
Declaration of Conformity................................................................................C-2

824 Reference Manual
xii
Appendix D Glossary D-1
Allowed Exposure Time (Ti) .......................................................................D-1
Average Sound Level (Lavg).......................................................................D-1
Calibration....................................................................................................D-2
Community Noise Equivalent Level (CNEL, Lden)....................................D-2
Criterion Duration (Tc) ................................................................................D-2
Criterion Sound Exposure (CSE).................................................................D-3
Criterion Sound Level (Lc) ..........................................................................D-3
Daily Personal Noise Exposure (LEP,d)......................................................D-3
Day-Night Average Sound Level (DNL, Ldn).............................................D-3
Decibel (dB).................................................................................................D-4
Department of Defense Level (LDOD)........................................................D-5
Dose..............................................................................................................D-5
Detector........................................................................................................D-5
Eight Hour Time-Weighted Average Sound Level (L TWA(8)).................D-5
Energy Equivalent Sound Level (Leq).........................................................D-5
Exchange Rate (Q), Exchange Rate Factor (q), Exposure Factor (k)..........D-6
Far Field .......................................................................................................D-6
Free Field......................................................................................................D-6
Frequency (Hz, rad/sec) ...............................................................................D-7
Frequency Band Pass Filter..........................................................................D-7
Frequency Filter - Weighted ........................................................................D-8
Leq................................................................................................................D-9
Level (dB) ....................................................................................................D-9
Measurement Duration (T).........................................................................D-10
Microphone Guidelines..............................................................................D-10
Near Field...................................................................................................D-12
Noise...........................................................................................................D-13
Noise Dose (D)...........................................................................................D-13
Noise Exposure ..........................................................................................D-13
OSHA Level (LOSHA)..............................................................................D-14
Preamplifier................................................................................................D-14
Projected Noise Dose.................................................................................D-14
Single Event Noise Exposure Level (SENEL, LAX) ................................D-14
Sound..........................................................................................................D-14
Sound Exposure (SE).................................................................................D-14
Sound Exposure Level (SEL, LET) ...........................................................D-15
Sound Pressure...........................................................................................D-15

824ReferenceManual
xiii
Sound Pressure Level (SPL, Lp)................................................................D-16
Sound Power(W)........................................................................................D-18
Sound Power Level (PWL, Lw).................................................................D-18
Sound Speed, (c,) .......................................................................................D-18
Spectrum (Frequency Spectrum)................................................................D-18
Threshold Sound Level (Lt).......................................................................D-18
Time Weighted Average Sound Level (TWA, LTWA(TC)).....................D-19
Time Weighting..........................................................................................D-19
Vibration.....................................................................................................D-19
Wavelength (l)............................................................................................D-19
Wavenumber (k).........................................................................................D-20

824 Reference Manual
xiv

11/8/00 Introduction 1-1
CHAPTER
1
Introduction
Welcome to the Larson Davis System 824. This versatile
instrument, with graphic display, performs the functions of
several instruments. It puts the combined features of a preci-
sion sound level meter and a real-time frequency analyzer in
the palm of your hand.
About This Manual
This manual has 12 chapters and 4 appendices covering the
following topics:
Chapters
•
Chapter 1 - Introduction:
Orients the user to the con-
tents of this user manual and the System 824’s features,
functions and measurement capabilities. It also includes
instructions on unpacking the System 824.
•
Chapter 2 - Overview:
Provides an overview of the
instrument’s capabilities and a description of each key
along with its function and displays. It also includes
instructions on working with menus.
•
Chapter 3
-
Front Panel Keys; their Functions and
Associated Menus:
Explains the functions associated
with each key on the 824.
•
Chapter 4 - Quick Start:
Guides users in the immediate
use of the System 824 including how to take measure-
ments, understanding the readings, and storing data in
the System 824.

1-2 824 Reference Manual 11/8/00
•
Chapter 5 - System 824 Instrument Modes
: Provides
descriptions of the System 824’s standard instrument
ID’s.
•
Chapter 6 - System 824 Views:
Gives you a detailed
description of the different display views available and
how to access them.
•
Chapter 7- Using ID Setting Files:
Describes how to
recall, customize and save IDs.
•
Chapter 8 - Printing a Report:
Describes how to print
a report of the data collected with the System 824.
•
Chapter 9 - Using the 824 Utility Software:
Describes
how to connect the 824 to a computer, in order to down-
load, translate and export data.
• Chapter 10 - RTA (Optional):
Explains how the RTA
high speed data gathering option enables you to perform
architectural acoustics, impulse event analysis, and
passby event analysis.
•
Chapter 11 - FFT (Optional):
Describes the features
and functions of the fast fourier analysis option.
•
Chapter 12 - AUD (Optional):
Explains how the AUD
option can be used to manually test an audiometer by
measuring level, frequency, linearity, THD, pulse,
crosstalk, frequency modulation, narrow band, broad
band, and speech noise.
Appendices
•
Appendix A - Integrated Level Calculations:
Provides
information on TWA Leq, SEL, dose and projected dose
calculations.
•
Appendix B - Serial Port Remote Control Interface:
Explains how to use the Serial Port Interface for Remote
Control of the System 824.
•
Appendix C - Technical Specifications:
Gives a listing
of acoustic, electronic, environmental, and physical char-
acteristics of the System 824