Name: Larson Davis 824
Brand: Larson Davis
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C-24 824 Reference Manual 9/29/09

Frequency Response

Random Incidence Microphone Correction

When random incidence correction is turned on in the 824, a

digital filter is added which gives the necessary correction to

provide random incidence response when measuring with a

free-field microphone.

NOTE: Tested with the preamplifier

and microphone attached directly to

the 824.

The graphs below show the response of the free-field

microphones before and after the random incidence

correction has been added.

Default Chapter5
- Table of Contents5
Chapter 1 Introduction21
- About this Manual21
- About this Chapter26
- Formatting26
- Features27
- Getting Started34
Chapter 2 Overview41
- System 824 Setups or Instrument Definitions41
- Instrument Definition (ID) Types42
- Selecting a Measurement Setup46
- Performing a Measurement; SLM&RTA (SSA)47
- Views51
  - Selecting a VIEW51
- Data Storage and Recall53
  - Storing Data53
  - Recalling Data53
- Calibration54
  - Correction of Calibrator Output Level57
Chapter 3 Front Panel Keys; Functions and Menus59
- Power Key61
- Run/Stop Key66
- R Reset Key67
- Pause Key68
- Lrud Arrow Keys69
- Check Key70
- View Key70
- D Data Key71
- S Setup Key72
- Ttools Key76
- P Print Key95
Chapter 4 Quick Start97
- Turning on and Calibrating the System 82497
  - High Range Calibration100
- Taking Measurements and Storing Data101
  - SLM&RTA Measurements101
  - Viewing RTA Displays During a Measurement104
- Recalling Stored Data107
- Selecting and Modifying Instrument Definitions (Ids)108
Chapter 5 System 824 Views121
- Status Icons and Indicators122
- General Views124
  - SLM Views125
  - Any Data View128
- SSA Specific Views129
  - SSA Displays131
- Logging SLM Specific Views143
Chapter 6 System 824 Virtual Instruments195
- Selecting an Instrument ID197
- Sound Spectrum Analyzer (SSA)197
- Logging SLM201
Chapter 7 Using ID Setting Files205
- Recalling ID Setting Files205
- Customizing Settings206
  - Settings Example - SLM&RTA (SSA)206
- Settings Descriptions208
- Common SLM Settings209
- Common Control Settings214
- Logging SLM TWA Settings221
- LOG and SSA Ln Settings224
- LOG and SSA Triggering Settings227
- LOG and SSA Wind/Tach Settings229
- LOG and SSA Time History Settings234
- LOG and SSA Interval Settings240
- Logging SLM Exceedance History Settings244
- Menu Layout of SSA Settings249
- Menu Layout of Integrating SLM (ISM) Settings254
- Menu Layout of Logging SLM Settings256
- Advanced Menu Layout260
- Check Menus263
Chapter 8 Printing a Report285
- Connecting the 824 to a Serial Printer285
- Printing Reports286
- Defining and Printing Tailored Reports289
  - Using the Recall Format (SSA and LOG Instruments Only)291
    - Default Settings Values for the Recall Format Reports292
- Printing a Custom Report307
Chapter 9 Performing a Sound Level Measurement313
- Configuration of the System313
- Selecting a Measurement Mode313
  - Selecting a Measurement ID314
- Editing the Microphone Parameters315
- Calibration315
- Entering the Noise Floor Values316
- Editing the Measurement Parameters317
- Positioning the Meter319
  - Use of a Windscreen319
- Selecting the SLM Display321
- Selecting the Measurement Range321
  - ISM and LOG Modes321
    - Selecting the Range Setting322
- Performing a Measurement323
  - Averaging Time324
- Linearity Range325
- Overload and under Range Conditions326
  - Overload Condition326
    - Reset326
  - Under Range Condition326
- Max, Min and Peak Values327
- Measuring for a Preset Integration Time328
  - Timer Mode328
- Measuring Using User-Selectable Thresholds329
Chapter 10 Using the 824 Utility Software331
- 824 Utility Installation331
- Starting the 824 Utility Software332
- Connecting to Your Computer332
- 824 Utility Tool Bar334
- 824 Utility Setup Window336
- Downloading Measurement Data347
- Translating Data from a Downloaded Binary File355
- Additional Features362
Chapter 11 RTA (Optional)367
- Settings Menu368
- Settings Descriptions372
- Display Views385
Chapter 12 FFT (Optional)409
- Features409
- Settings Menu409
- Settings Descriptions411
- FFT Display414
  - Fft414
  - FFT Check Menu416
- THD (Total Harmonic Distortion)417
  - THD Check Menu418
- Snapshot419
  - Snapshot Check Menu420
- FFT Calibration421
Chapter 13 AUD (Optional)431
- Connecting the Test System432
- Selecting the 824-AUD Operation Mode433
- Microphone Sensitivity Calibration434
- AUD Modes434
- FFT Display455
Appendix A Serial Port Interface Remote Control457
- Interface Cables458
  - Connection to a Computer Using CBL006459
- Daisy Chain Addressing461
  - 824 Network, Addressing Commands462
- Commands464
- Remote Control Commands (Detailed465
- Setting Commands486
- Setting List493
- History Data Variables513
- Print Command525
- Error Messages and Warnings527
- Modem Control Mode (All Instruments530
- Unsupported Miscellaneous Commands534
- Data File Commands535
- Keyboard Simulation536
- Operation Notes537
Appendix B Integrated Level Calculations539
- Technical Specifications547
Appendix C Technical Specifications548
- Declaration of Conformity548
- General Specifications549
- 1/1 and 1/3 Octave Filters566
  - Filter Shapes566
- Frequency Response570
- Power/Current Draw of 824 Using External Power595
Appendix D Glossary597
- Average Sound Level (Lavg597
- Community Noise Equivalent Level (CNEL, Lden598
- Criterion Duration (Tc599
- Criterion Sound Exposure (CSE599
- Criterion Sound Level (Lc599
- Daily Personal Noise Exposure Lep,D599
- Day-Night Average Sound Level (DNL, Ldn599
- Decibel (Db)600
- Department of Defense Level (LDOD604
- Dose604
- Detector604
- Eight Hour Time-Weighted Average Sound Level (L TWA(8604
- Energy Equivalent Sound Level (Leq604
- Exchange Rate (Q), Exchange Rate Factor (Q), Exposure Factor (K604
- Far Field605
- Frequency (Hz, Rad/Sec605
- Frequency Band Pass Filter606
- Frequency Filter - Weighted606
- Leq608
- Level (Db608
- Measurement Duration (T608
- Microphone Guidelines608
- Near Field611
- Noise611
- Noise Dose (D612
- Noise Exposure613
- OSHA Level (LOSHA613
- Projected Noise Dose613
- Single Event Noise Exposure Level (SENEL, LAX613
- Sound613
- Sound Exposure (SE614
- Sound Exposure Level (SEL, LET614
- Sound Pressure615
- Sound Pressure Level (SPL, Lp616
- Sound Power(W617
- Sound Power Level (PWL, Lw617
- Sound Speed, (C618
- Spectrum (Frequency Spectrum618
- Threshold Sound Level (Lt618
- Time Weighted Average Sound Level (TWA, LTWA(TC618
- Time Weighting619
- Wavelength (L619
- Wavenumber (K619
Appendix E Memory Usage621
- LOG Memory Usage621
- 824-SSA Memory Usage627
  - Interval Records (Intv History Enabled627
  - Time History Records (Time History Enabled628
Appendix F SLM Testing to IEC61672-1631
- Reference Sound Pressure Level631
- Reference Level Range631
- Microphone Reference Point631
- Average Frequency Response Corrections632
- Periodic Testing of A-Weighted Sound Levels634
- A-Weighted Sound Levels at Upper and Lower Limits of the Linear Operating Range635
- Electrical Signal Input Device635
- Inherent Noise635
- Maximum Sound Pressure Level636
- Power Supply Voltage Range636
- Display Device636
- Stabilization Time Following Changes of Environmental Conditions636
- Electric Field Strength above 10 V/M636
- Greatest Radio Frequency Emission Levels636
- Effect of Electrostatic Discharges637
- Greatest Susceptibility to AC Power and Radio Frequency Fields637
Appendix G Miscellaneous Information639

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Larson Davis 824 Specifications

General

Brand	Larson Davis
Model	824
Category	Measuring Instruments
Language	English

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