Larson Davis System 824 Product manual

Model 824
Precision Sound Level Meter
& Real Time Analyzer
Reference Manual

I824.01 Rev P
Technical Reference Manual
Larson Davis
Model 824

Copyright
Copyright 2006, 2007, 2008, 2009 by PCB Piezotronics, Inc. This manual is copyrighted, with all
rights reserved. The manual may not be copied in whole or in part for any use without prior written
consent of PCB Piezotronics, Inc.
Disclaimer
The following paragraph does not apply in any state or country where such statements are not
agreeable with local law:
Even though PCB Piezotronics, Inc. has reviewed its documentation, PCB Piezotronics Inc. makes no
warranty or representation, either expressed or implied, with respect to this instrument and
documentation, its quality, performance, merchantability, or fitness for a particular purpose. This
documentation is subject to change without notice, and should not be construed as a commitment or
representation by PCB Piezotronics, Inc.
This publication may contain inaccuracies or typographical errors. PCB Piezotronics, 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.
Record of Serial Number and Purchase Date
Model 824 Serial Number: ___________
PRM902 Preamplifier Serial Number: ___________
Microphone Model: _________ Serial Number: ___________
Recycling
PCB Piezotronics, Inc. is an environmentally friendly organization and encourages our customers to
be environmentally conscious. When this product reaches its end of life, please recycle the product
through a local recycling center or return the product to:
PCB Piezotronics, Inc.
Attn: Recycling Coordinator
1681 West 820 North
Provo, Utah, USA 84601-1341
where it will be accepted for disposal

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Chapter 1 Introduction 1-1
About This Manual .................................................................................................1-1
Special Features of the Electronic Version........................................................1-3
Bookmarks .........................................................................................................1-3
Opening Bookmarks......................................................................................1-3
Closing Bookmarks.......................................................................................1-4
Expanding Bookmarks ..................................................................................1-4
Click to Display Page....................................................................................1-5
Return to Previous View ...............................................................................1-5
Links...................................................................................................................1-5
Click to Display Page....................................................................................1-5
About This Chapter.................................................................................................1-6
Formatting...............................................................................................................1-6
Features...................................................................................................................1-7
Hardware Features: ............................................................................................1-7
System 824 Components..................................................................................1-10
System Diagram...............................................................................................1-13
Getting Started ......................................................................................................1-14
Unpacking and Inspection................................................................................1-14
..........................................................................................................................1-16
Comments concerning the Digital Signal Processor...................................1-16
Accessories and Optional Equipment ..............................................................1-16
Connecting Internal or External Power............................................................1-18
Using the NiMH Battery Pack ....................................................................1-18
Using Alkaline Batteries or Individual NiMH rechargable cells. ...............1-19
Using the AC Power Adapter......................................................................1-20
Chapter 2 Overview 2-1
System 824 Setups or Instrument Definitions ........................................................2-1
Instrument Definition (ID) Types ..........................................................................2-2
Write Protect, Delete, Write Enable IDs............................................................2-2
SLM&RTA (SSA) .............................................................................................2-2
SLM (ISM) ........................................................................................................2-4
Logging (LOG) ..................................................................................................2-4
Selecting a Measurement Setup..............................................................................2-6
Performing a Measurement; SLM&RTA (SSA) ....................................................2-7
Stop, Pause and Back Erase Functions ..............................................................2-8
Stopping and Starting Measurements............................................................2-8

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Pausing Measurements..................................................................................2-8
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..................................................2-10
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
Storing Data.................................................................................................2-13
Recalling Data.............................................................................................2-13
Calibration ............................................................................................................2-14
Correction of Calibrator Output Level.............................................................2-17
Chapter 3 Front Panel Keys; Functions and Menus 3-1
vPower Key .........................................................................................................3-3
Power-up the Instrument / Viewing PWR Display............................................3-4
Power Settings....................................................................................................3-6
Extra Notes on Power Conservation ..................................................................3-8
sRun/Stop Key ....................................................................................................3-8
RReset Key ..........................................................................................................3-9
pPause Key........................................................................................................3-10
Pause............................................................................................................3-10
Pause, Back Erase .......................................................................................3-10
Preview........................................................................................................3-11
lrud Arrow Keys.................................................................................3-11
cCheck Key........................................................................................................3-12
VView Key.........................................................................................................3-12
DData Key..........................................................................................................3-13
SSetup Key ........................................................................................................3-14
Save ID........................................................................................................3-16
Title .............................................................................................................3-16
ID Name ......................................................................................................3-16
Write Protect, Delete, Write Enable IDs..........................................................3-17
TTools Key .........................................................................................................3-18
About................................................................................................................3-20
Calibration........................................................................................................3-22
Clock/Timer .....................................................................................................3-23

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Memory............................................................................................................3-27
Deleting Stored Data........................................................................................3-29
Delete Last Function ...................................................................................3-29
824 Memory Structure ................................................................................3-29
Deleting the Last Stored Record .................................................................3-30
Deleting Individual Records........................................................................3-31
Power Monitor .................................................................................................3-33
Communication................................................................................................3-34
PPrint Key..........................................................................................................3-37
Chapter 4 Quick Start 4-1
Turning On and Calibrating the System 824 ..........................................................4-1
High Range Calibration .....................................................................................4-4
Taking Measurements and Storing Data.................................................................4-5
SLM&RTA Measurements................................................................................4-5
Viewing RTA Displays during a Measurement.................................................4-8
Recalling Stored Data ...........................................................................................4-11
Selecting and Modifying Instrument Definitions (IDs)........................................4-12
The Setup Menu...............................................................................................4-13
The Active ID...................................................................................................4-13
Menu Scrolling.................................................................................................4-15
Permanent IDs..................................................................................................4-15
Write-protected IDs..........................................................................................4-16
Preparing for a Measurement...........................................................................4-16
Selecting a Different ID ...................................................................................4-17
Accessing the Settings Menu ...........................................................................4-17
Accessing the Settings Menu to Initiate Editing or Modification....................4-18
Setting Control in the SLM View ....................................................................4-22
Chapter 5 System 824 Views 5-1
Status Icons and Indicators .....................................................................................5-2
General Views.........................................................................................................5-4
SLM Views ........................................................................................................5-5
Any Data View...................................................................................................5-8
Any Level Format .........................................................................................5-8
Any Impulse Format......................................................................................5-8
Any Time Format..........................................................................................5-9
SSA Specific Views................................................................................................5-9
SSA Displays ...................................................................................................5-11

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SSA Displays Including 1/1 or 1/3 Octave Spectral Data...........................5-11
Tabular SSA Views.....................................................................................5-12
Time History Displays ................................................................................5-13
SSA Intervals...............................................................................................5-13
SSA Time History .......................................................................................5-16
Run Log.......................................................................................................5-19
Ln Centiles ..................................................................................................5-19
Logging SLM Specific Views ..............................................................................5-23
Current SLM and Overall SLM Views............................................................5-25
Current SLM/Overall SLM Display-a (SPL)..............................................5-26
Current/Overall SLM Display-b (Times)....................................................5-28
Current/Overall SLM Display-c (Min/Max)...............................................5-29
Current/Overall SLM Display-d (Peaks).....................................................5-29
Current/Overall SLM Display-e (TWA).....................................................5-30
Exposure Views ...............................................................................................5-31
Exposure Display-a .....................................................................................5-32
Exposure-b Display.....................................................................................5-33
Exposure-c Display .....................................................................................5-34
Ln Centiles Views............................................................................................5-35
Ln-a Display................................................................................................5-35
Ln-b Display................................................................................................5-36
Stats Views.......................................................................................................5-37
Stats-a Display.............................................................................................5-38
Stats-b Display ............................................................................................5-38
Stats-c Display.............................................................................................5-39
Run Log (LOG & SSA) ...................................................................................5-40
Time History ....................................................................................................5-42
Single Other Level ......................................................................................5-43
Multiple Other Levels .................................................................................5-43
Intervals............................................................................................................5-44
Intervals-a Display ......................................................................................5-44
Intervals-b Display ......................................................................................5-46
Intervals-c Display ......................................................................................5-47
Intervals-d Display ......................................................................................5-48
Intervals-e Display ......................................................................................5-49
Intervals-f Display.......................................................................................5-50
Exceedance History..........................................................................................5-52
Excd-a Display ............................................................................................5-52

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Excd-b Display............................................................................................5-53
Excd-c Display ............................................................................................5-54
Excd Time History Display.........................................................................5-55
Daily Views......................................................................................................5-58
Daily-a Display ...........................................................................................5-58
Daily-b Display ...........................................................................................5-60
Daily-c Wind Display..................................................................................5-61
Daily-d Windy Percent Display ..................................................................5-62
Hourly Leq Display.....................................................................................5-63
Metrics .............................................................................................................5-65
Metrics-a Display ........................................................................................5-65
Metrics-b Display........................................................................................5-66
PassBy..............................................................................................................5-67
Wind/Tach........................................................................................................5-69
Wind-a Display ...........................................................................................5-69
Wind-b Display ...........................................................................................5-70
Wind-c Percent Display ..............................................................................5-71
Chapter 6 System 824 Virtual Instruments 6-1
System 824 Virtual Instruments .............................................................................6-1
Selecting an Instrument ID .....................................................................................6-3
Sound Spectrum Analyzer (SSA) ...........................................................................6-3
SSA Measuring Ranges .....................................................................................6-4
LN Percentiles (Spectral)...................................................................................6-5
AC/DC Output ...................................................................................................6-5
Logging SLM..........................................................................................................6-7
Time History ......................................................................................................6-7
Interval History ..................................................................................................6-7
Exceedances.......................................................................................................6-8
LN Percentiles (Broadband)...............................................................................6-8
Sound Exposure .................................................................................................6-9
............................................................................................................................6-9
LOG and ISM Measuring Ranges......................................................................6-9
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

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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) ..........................................................................7-7
Transducer Setting - (SSA, LOG, ISM)..........................................................7-8
Random Incidence Microphone Correction - (Available to all Instrument
types) .............................................................................................................7-8
Pk Weighting - (SSA, LOG, ISM) ..................................................................7-9
RTA Detector Setting - (SSA) ......................................................................7-9
RTA Weighting - (SSA)...............................................................................7-10
Bandwidth Setting - (SSA)...........................................................................7-10
Common Control Settings................................................................................7-10
Control Settings - (ISM)..............................................................................7-10
Control Settings _(SSA, LOG)....................................................................7-11
AC/DC Output Settings - (SSA, LOG, ISM) ................................................7-12
Logic Input Setting - (SSA, LOG, ISM) .......................................................7-12
Logic Output Setting - (SSA, LOG, ISM) ....................................................7-13
Logic Output Time Setting - (SSA, LOG, ISM) ...........................................7-15
Logic Output #2 ..........................................................................................7-16
Logic Output #2 Time Setting.....................................................................7-16
Heater On ....................................................................................................7-16
E. A. Cal Tone.............................................................................................7-16
Logging SLM TWA Settings...........................................................................7-17
Ovll Exchange - (LOG) ...............................................................................7-17
Ovll Threshold - (LOG)...............................................................................7-18
Ovll Criterion - (LOG) ................................................................................7-18
Criterion Time - (LOG)...............................................................................7-19
Crnt Exchange - (SSA, ISM, LOG).............................................................7-19
Crnt Threshold (SSA, ISM, LOG) ..............................................................7-20
Crnt Criterion (LOG) ..................................................................................7-20
LOG and SSA Ln Settings...............................................................................7-20
Enable Ln ....................................................................................................7-21
Start Level ...................................................................................................7-21
Ln’s .............................................................................................................7-22
Spectral Ln’s (SSA only) ............................................................................7-22
LOG and SSA Triggering Settings ..................................................................7-23
SPL Excd Lvl 1 - (LOG, SSA) .....................................................................7-23

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SPL Excd Lvl 2 - (LOG, SSA) .....................................................................7-23
PK Excd Lvl 1 - (LOG, SSA) .......................................................................7-24
Pk Excd Lvl 2 - (LOG, SSA)........................................................................7-24
Hysteresis - (LOG, SSA) ..............................................................................7-24
LOG and SSA Wind/Tach Settings .................................................................7-25
Setup of Wind/Tach Function .....................................................................7-26
Wind Scale ..................................................................................................7-27
Wind Units ..................................................................................................7-28
Direction Units ............................................................................................7-28
Wind/Tach Enable.......................................................................................7-29
Windy Threshold.........................................................................................7-29
Wind Exceedance Level..............................................................................7-29
Windy Hysteresis ........................................................................................7-29
Wind Pause Enable......................................................................................7-30
Pulse Trigger Voltage..................................................................................7-30
Pulse Source ................................................................................................7-30
LOG and SSA Time History Settings ..............................................................7-30
Hist Enable - (LOG, SSA) ............................................................................7-32
Hist Period (LOG, SSA) ...............................................................................7-33
Period Units - (LOG, SSA)...........................................................................7-33
Other Level - (LOG only)............................................................................7-33
Resolution - (LOG, SSA)..............................................................................7-34
Advanced Time History - (LOG, SSA).......................................................7-35
Marker Text - (LOG, SSA) .........................................................................7-35
LOG and SSA Interval Settings.......................................................................7-36
Intv Enable - (LOG, SSA) ............................................................................7-37
Intv Period - (LOG, SSA).............................................................................7-37
Intv Time Sync - (LOG, SSA) ......................................................................7-37
Intv Save Ln’s - (LOG, SSA)......................................................................7-38
Intv Auto Stop - (LOG, SSA) .......................................................................7-38
Intv Threshold - (LOG, SSA) .......................................................................7-39
Intv Exchange - (LOG, SSA)........................................................................7-39
Intv Spectrum - (SSA only).........................................................................7-39
Logging SLM Exceedance History Settings....................................................7-40
Triggering - (LOG)......................................................................................7-40
Excd Enable - (LOG)...................................................................................7-40
Min Duration - (LOG).................................................................................7-40
Excd Time Hist - (LOG)..............................................................................7-41

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T.H. Period - (LOG) ....................................................................................7-41
Excd Trigger - (LOG)..................................................................................7-41
Excd Time - (LOG) .....................................................................................7-41
Timed Excd Period - (LOG)........................................................................7-41
Daily Enable - (LOG)..................................................................................7-42
Daily Ln’s - (LOG)......................................................................................7-42
Logging SLM Define Report Settings .............................................................7-42
Data Report - (LOG, SSA)............................................................................7-43
Setup Report - (LOG, SSA) ........................................................................7-43
SPL Histogram - (LOG) ..............................................................................7-44
Pk-1 Histogram - (LOG) .............................................................................7-44
Pk-2 Histogram - (LOG) .............................................................................7-44
Intv Report - (LOG, SSA).............................................................................7-44
Hist Report - (LOG, SSA) ............................................................................7-45
Menu Layout of SSA Settings ..............................................................................7-45
Menu Layout of Integrating SLM (ISM) Settings................................................7-50
Menu Layout of Logging SLM Settings...............................................................7-52
Advanced Menu Layout........................................................................................7-56
Check Menus ........................................................................................................7-59
Check Menu Example......................................................................................7-60
SLM Check Menu Options (SSA and LOG) ...................................................7-62
Mark Display...............................................................................................7-62
Graph Menu.................................................................................................7-64
Settings........................................................................................................7-65
Controls Settings Menu...............................................................................7-65
Other SSA Check Menus .................................................................................7-65
Any Data Check Menu................................................................................7-65
RTA Check Menu .......................................................................................7-66
Intervals Check Menu .................................................................................7-67
Time History Check Menu..........................................................................7-68
Run Log Check Menu .................................................................................7-69
Ln Centiles Check Menus ...........................................................................7-70
Other Logging (LOG) Check Menus ...............................................................7-73
Any Data Check Menu................................................................................7-73
Current SLM / Overall SLM Check Menu..................................................7-73
Exposure Check Menu ................................................................................7-73
LN Centiles Check Menu............................................................................7-74
Stats Check Menu........................................................................................7-75

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Run Log Check Menu .................................................................................7-75
Time History Check Menu..........................................................................7-76
Intervals Check Menu .................................................................................7-76
Excd History Check Menu ..........................................................................7-77
Daily History Check Menu .........................................................................7-78
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 .....................................................................................8-23
Chapter 9 Performing a Sound Level Measurement 9-1
Configuration of the System...................................................................................9-1
Selecting a Measurement Mode..............................................................................9-1
Selecting a Measurement ID ..............................................................................9-2
Editing the Microphone Parameters .......................................................................9-3
Calibration ..............................................................................................................9-3
Entering the Noise Floor Values.............................................................................9-4
Editing the Measurement Parameters .....................................................................9-5
Positioning the Meter..............................................................................................9-7
Use of a Windscreen ..........................................................................................9-7
Selecting the SLM Display.....................................................................................9-9
Selecting the Measurement Range..........................................................................9-9
ISM and LOG Modes.........................................................................................9-9
Selecting the Range Setting.........................................................................9-10
SSA Mode........................................................................................................9-10
Performing a Measurement...................................................................................9-11
Averaging Time ...............................................................................................9-12
Linearity Range.....................................................................................................9-13
Overload and Under Range Conditions ................................................................9-14
Overload Condition..........................................................................................9-14
Reset............................................................................................................9-14
Under Range Condition ...................................................................................9-14
Max, Min and Peak Values...................................................................................9-15
Measuring for a Preset Integration Time ..............................................................9-16
Timer Mode......................................................................................................9-16

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Measuring using User-Selectable Thresholds.......................................................9-17
Chapter 10 Using the 824 Utility Software 10-1
824 Utility Installation ..........................................................................................10-1
Starting the 824 Utility Software..........................................................................10-2
Connecting to Your Computer..............................................................................10-2
824 Utility Tool Bar..............................................................................................10-4
824 Utility Setup Window ....................................................................................10-6
Retrieving setups from the 824 ........................................................................10-7
Modifying and Storing Setups to the 824 ........................................................10-9
Changing System Settings...........................................................................10-9
Manipulating a Setup ................................................................................10-10
Saving Setups to Disk Files ...........................................................................10-12
Opening Setup Disk Files ..............................................................................10-12
Creating a New Setup ....................................................................................10-14
Renaming an Existing Setup..........................................................................10-15
Deleting an Existing Setup.............................................................................10-16
Locking and Unlocking Setups......................................................................10-17
Downloading Measurement Data .......................................................................10-17
Specifying a Destination File.........................................................................10-18
Changing the Download File Name...............................................................10-20
Adding Notes to a download file ...................................................................10-21
Selecting Active Measurements or Data Files ...............................................10-21
Downloading the Measurement .....................................................................10-22
Explanation of files in the 824 Utility Directory ...........................................10-24
Translating Data from a Downloaded Binary File..............................................10-25
Selecting a Data set to view ...........................................................................10-27
Printing a Translated File...............................................................................10-29
Viewing a Translated File Within a Spreadsheet Program ............................10-31
Additional Features.............................................................................................10-32
Chapter 11 RTA (optional) 11-1
Settings Menu .......................................................................................................11-2
Settings Descriptions ............................................................................................11-6
RTA Settings Menu .........................................................................................11-6
Autostore Settings Menu..................................................................................11-8
Arm Settings Menu ..........................................................................................11-9
Trigger Settings Menu ...................................................................................11-11
End Settings Menu.........................................................................................11-12

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Then Settings Menu .......................................................................................11-14
Trigger Settings Menu (continued)................................................................11-14
RT60 Reverberation Time Settings................................................................11-16
RT60-A and RT60-B Instrument Definition..................................................11-17
Qualifying Background Noise: Rooms [RTA] ID .........................................11-18
Display Views.....................................................................................................11-19
RTA Views ....................................................................................................11-19
Trigger Views ................................................................................................11-23
Autostore Views.............................................................................................11-25
Autostore ByTime Spectral History...............................................................11-29
ByTime Spectrum Check Menu.....................................................................11-30
ByTime Graph Check Menu..........................................................................11-31
RT-60 .............................................................................................................11-33
RT60 Check Menu.........................................................................................11-35
Spatial Avg Views .........................................................................................11-35
Spatial Avg Check Menu ...............................................................................11-37
Avg History Check Menu ..............................................................................11-38
Rooms Views .................................................................................................11-39
Chapter 12 FFT (Optional) 12-1
Features.................................................................................................................12-1
Settings Menu .......................................................................................................12-1
Settings Descriptions ............................................................................................12-3
FFT Display ..........................................................................................................12-6
FFT...................................................................................................................12-6
FFT Check Menu .............................................................................................12-8
THD (Total Harmonic Distortion)........................................................................12-9
THD Check Menu..........................................................................................12-10
Snapshot..............................................................................................................12-11
Snapshot Check Menu ...................................................................................12-12
FFT Calibration...................................................................................................12-13
Calibrating dB to a Different Reference ........................................................12-13
Displaying Amplitude in Linear Units...........................................................12-14
Setup of Linear Units Readout..................................................................12-15
Frequently Asked Questions Concerning FFT...............................................12-17
Chapter 13 AUD (Optional) 13-1
Connecting the Test System .................................................................................13-2
Selecting the 824-AUD Operation Mode .............................................................13-3

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Microphone Sensitivity Calibration......................................................................13-4
AUD Modes..........................................................................................................13-4
View Menu.......................................................................................................13-5
SLM/RTA Submenu ...................................................................................13-5
FFT Submenu..............................................................................................13-5
Pulse/FM Submenu .....................................................................................13-5
Display Sequence.............................................................................................13-6
SLM+RTA Live Display .................................................................................13-6
SLM+RTA Live Check Menu.....................................................................13-7
Any Level -a, -b and -c Displays .....................................................................13-8
Any Level Check Menu ..............................................................................13-9
Linearity RTA Display...................................................................................13-10
Manual Lock .............................................................................................13-12
Automatic Lock.........................................................................................13-12
Linearity RTA Check Menu......................................................................13-13
Linearity FFT Display....................................................................................13-14
Manual Lock .............................................................................................13-16
Automatic Lock.........................................................................................13-16
Linearity FFT Check Menu.......................................................................13-17
Flatness FFT Display .....................................................................................13-18
THD Display..................................................................................................13-19
THD Check Menu .....................................................................................13-21
Pulse/FM Display...........................................................................................13-21
Pulse/FM-a Display...................................................................................13-22
Pulse/FM-b Display...................................................................................13-24
Pulse/FM Check Menu..............................................................................13-24
FFT Display ........................................................................................................13-25
FFT Check Menu ......................................................................................13-25
Appendix A Serial Port Interface Remote Control A-1
Interface Cables .....................................................................................................A-2
Connection to a computer using CBL006....................................................A-3
‘Daisy Chain Addressing.......................................................................................A-5
824 Network, Addressing Commands ..............................................................A-6
Commands .............................................................................................................A-8
Remote Control Commands (Detailed) .................................................................A-9
Mode Commands ..............................................................................................A-9
“Read” Commands (Reads out data variables)...............................................A-10
“ANY DATA” READ COMMANDS............................................................A-25

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Other Read Commands ...................................................................................A-28
Group Read Programming ..............................................................................A-29
Setting Commands...............................................................................................A-30
Querying Settings............................................................................................A-31
Ln Query Commands (SSA)...........................................................................A-33
Entering Settings.............................................................................................A-33
Option Settings...........................................................................................A-33
Numeric Settings........................................................................................A-35
Character String Settings............................................................................A-35
Template Settings.......................................................................................A-36
Setting List...........................................................................................................A-37
Histogram Reports ..........................................................................................A-44
Tailored Report ..........................................................................................A-45
Miscellaneous.............................................................................................A-45
Error Checking I/O..........................................................................................A-48
RTA Settings Commands................................................................................A-51
History Records...............................................................................................A-54
Types of History.........................................................................................A-55
Advance......................................................................................................A-55
Backup........................................................................................................A-56
Find.............................................................................................................A-56
History Data Variables.........................................................................................A-57
Exceedance History Variables ........................................................................A-57
Interval History Variables (“I” Commands) ...................................................A-59
Daily History Variables - (D1-D102) ............................................................A-64
Run Log Variables (SSA, ISM, LOG, TAL) ..................................................A-65
Calibration History Variables (LOG) .............................................................A-66
Time History Variables (SSA, LOG, TAL)....................................................A-67
Time History Variables (SSA, LOG, TAL)....................................................A-68
Histogram Table Variables .............................................................................A-68
Print Command....................................................................................................A-69
Error Messages and Warnings .............................................................................A-71
Modem Control Mode (All Instruments).............................................................A-74
Modem Mode..................................................................................................A-74
Dial Out Mode ................................................................................................A-74
Monitor Number .............................................................................................A-75
824 Phone Dialing Procedure .........................................................................A-75
Model 824 Answering Procedure ...................................................................A-76

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Unsupported Miscellaneous Commands .............................................................A-78
Data File Commands ...........................................................................................A-79
Keyboard Simulation ...........................................................................................A-80
Operation Notes ...................................................................................................A-81
Appendix B Integrated Level Calculations B-1
Appendix C Technical Specifications C-1
Declaration of Conformity................................................................................C-2
1/1 and 1/3 Octave Filters ...............................................................................C-20
Frequency Range........................................................................................C-20
Filter Shapes:..............................................................................................C-20
Frequency Response .......................................................................................C-24
Power/Current Draw of 824 Using External Power........................................C-49
Appendix D Glossary D-1
Allowed Exposure Time (Ti) .......................................................................D-1
Average Sound Level (Lavg) .......................................................................D-2
Community Noise Equivalent Level (CNEL, Lden)....................................D-2
Criterion Duration (Tc) ................................................................................D-3
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-8
Dose..............................................................................................................D-8
Detector ........................................................................................................D-8
Eight Hour Time-Weighted Average Sound Level (L TWA(8)).................D-8
Energy Equivalent Sound Level (Leq).........................................................D-8
Exchange Rate (Q), Exchange Rate Factor (q), Exposure Factor (k) ..........D-8
Far Field .......................................................................................................D-9
Free Field......................................................................................................D-9
Frequency (Hz, rad/sec) ...............................................................................D-9
Frequency Band Pass Filter........................................................................D-10
Frequency Filter - Weighted ......................................................................D-10
Leq..............................................................................................................D-12
Level (dB) ..................................................................................................D-12
Measurement Duration (T).........................................................................D-12

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Microphone Guidelines..............................................................................D-12
Near Field...................................................................................................D-15
Noise...........................................................................................................D-15
Noise Dose (D)...........................................................................................D-16
Noise Exposure ..........................................................................................D-17
OSHA Level (LOSHA)..............................................................................D-17
Preamplifier................................................................................................D-17
Projected Noise Dose .................................................................................D-17
Single Event Noise Exposure Level (SENEL, LAX) ................................D-17
Sound..........................................................................................................D-17
Sound Exposure (SE) .................................................................................D-18
Sound Exposure Level (SEL, LET) ...........................................................D-18
Sound Pressure ...........................................................................................D-19
Sound Pressure Level (SPL, Lp)................................................................D-20
Sound Power(W)........................................................................................D-21
Sound Power Level (PWL, Lw).................................................................D-21
Sound Speed, (c,) .......................................................................................D-22
Spectrum (Frequency Spectrum)................................................................D-22
Threshold Sound Level (Lt) .......................................................................D-22
Time Weighted Average Sound Level (TWA, LTWA(TC)).....................D-22
Time Weighting..........................................................................................D-23
Vibration.....................................................................................................D-23
Wavelength (l)............................................................................................D-23
Wavenumber (k).........................................................................................D-23
Appendix E Memory Usage E-1
LOG Memory Usage ............................................................................................. E-1
Exceedance Records (Exceedance History Enabled)] ...................................... E-1
Interval Records (Intv History Enabled)........................................................... E-2
Daily Records (Daily History Enabled) ............................................................ E-2
Time History Records (Time History Enabled)................................................ E-2
Other Histories and Memory Usage.................................................................. E-2
Estimating Memory Usage: .............................................................................. E-3
824-LOG Memory Usage Worksheet............................................................... E-5
824-SSA Memory Usage ....................................................................................... E-7
Interval Records (Intv History Enabled)........................................................... E-7
Time History Records (Time History Enabled)................................................ E-8
Appendix F SLM Testing to IEC61672-1 F-1

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Reference Sound Pressure Level:................................................................. F-1
Reference Level Range: ............................................................................... F-1
Microphone Reference Point:....................................................................... F-1
Average Frequency Response Corrections .................................................. F-2
Periodic Testing of A-Weighted Sound Levels............................................ F-4
A-Weighted Sound Levels at Upper and Lower Limits of the Linear Operating
Range............................................................................................................ F-5
Electrical Signal Input Device..................................................................... :F-5
Inherent Noise: ............................................................................................. F-5
Maximum Sound Pressure Level: ................................................................ F-6
Power Supply Voltage Range: ..................................................................... F-6
Display Device ............................................................................................. F-6
Stabilization Time Following Changes of Environmental Conditions: ....... F-6
Electric Field Strength Above 10 V/m:........................................................ F-6
Greatest Radio Frequency Emission Levels: ............................................... F-6
Effect of Electrostatic Discharges................................................................ F-7
Greatest Susceptibility to AC Power and Radio Frequency Fields:............. F-7
...................................................................................................................... F-7
Appendix G Miscellaneous Information G-1