Extech Instruments 407790A User manual

User Manual
Real Time Octave Band Analyzer
Model 407790A
Additional User Manual Translations available at www.extech.com

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Table of Contents
TABLE OF CONTENTS ..........................................................................................2
1. INTRODUCTION................................................................................................3
1.1 Instrument Care ............................................................................................4
1.2 Features........................................................................................................5
2. DESCRIPTIONS ................................................................................................6
2.1 Meter Description..........................................................................................6
2.2 Operation Buttons.........................................................................................8
2.3 Display Screen............................................................................................10
2.4 Analysis screen...........................................................................................12
2.5 Numeric Display screen..............................................................................13
3. MEASUREMENT PREPARATION AND SETUP ............................................15
3.1 Setting the Date and Time ..........................................................................15
3.2 SD Memory Card ........................................................................................17
3.3 Setting the Backlight Auto Off time .............................................................17
3.4 Sub Channel Settings.................................................................................18
3.5 Selecting the Lmax/Lmin type ....................................................................19
3.6 Comparator Output Operation ....................................................................20
3.7 Trigger Mode Setup and Operation ............................................................23
4. MEASUREMENTS...........................................................................................27
4.1 Sound Level Measurements.......................................................................27
4.2 SEL, Leq, Lmax, Lmin, LN Measurements.................................................28
4.3 Sound Level and Octave Band Analysis Measurement .............................30
4.4 Sound Band - Leq, SEL, Lmax, Lmin and LN Analysis Measurement .......32
5. STORING DATA TO MEMORY .......................................................................34
5.1 Manual Memory Storage ............................................................................34
5.2 Recalling Manually Stored Data .................................................................37
5.3 Erasing Manually Stored Data....................................................................39
5.4 Auto 1 Memory Storage..............................................................................40
5.5 Auto 2 Memory Storage..............................................................................44
5.6 Erasing Auto Stored Data ...........................................................................45
6. SOFTWARE DOWNLOAD AND INSTALLATION ..........................................47
7. SOUND PRESSURE LEVEL - TECHNICAL NOTES .....................................48
8. CALIBRATION.................................................................................................49
9. SPECIFICATIONS ...........................................................................................50
10. TWO-YEAR WARRANTY................................................................................53

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1. Introduction
Congratulations on your purchase of the Extech 407790A Real Time Octave Band
Analyzer. This auto ranging Type 2 integrating sound level meter features 1/1 and 1/3
Octave Band real-time noise analyses. The 407790A offers five measurement
parameters: SPL (Sound Pressure Level), Leq (Equivalent Continuous Sound Pressure
Level), SEL (Sound Exposure Level), Lmax (Maximum Sound Pressure Level), and Lmin
(Minimum Sound Pressure Level). The built-in memory stores 12,280 data records in
sound level mode and 1024 records in Octave mode. The stored data can be easily
transferred to a PC with the 407790A software and USB cable. This meter permits
choice of ‘A’, ‘C’, or Flat ’Z’ weighting and Slow / Fast /impulse response times. AC and
DC analog output signals are available for chart recorders and other external recording
devices. Careful use of this device will provide years of reliable service.

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1.1 Instrument Care
Do not attempt to remove the mesh cover from the microphone as this will cause damage
and affect the accuracy of the instrument.
Protect the instrument from impact. Do not drop it or subject it to rough handling.
Transport it in the supplied carrying case.
Protect the instrument from water, dust, extreme temperatures, high humidity and direct
sunlight during storage and use.
Protect the instrument from air with high salt or sulfur content, gases and stored chemicals,
as this may damage the delicate microphone and sensitive electronics.
Always switch the instrument off after use. Remove the batteries from the instrument if it
is not to be used for a long period of time. Do not leave exhausted batteries in the
instrument, as they may leak and cause damage.
Clean the instrument only by wiping it with a soft, dry cloth or, when necessary, with a cloth
lightly moistened with water. Do not use solvents, abrasives, alcohol or cleaning agents

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1.2 Features
The Sound Level Meter complies with the requirements of IEC 61672-1:2003 standard for a
Class 2 instrument. See specifications section for more applicable standards that apply to this
meter.
1/1 octave band analysis from 31.5Hz to 8kHz
1/3 octave band analysis from 25Hz to 10kHZ
Can perform 1/1 and 1/3 octave band analysis simultaneously
4GB Micro SD card
USB interface
Datalogging function
AC/DC signal output available for level and graphic recorder
Comparator output function
External trigger input function
Real time clock with calendar
Main channel (sound meter, analyzer mode)
Sub Channel (sound level meter mode)
The 407790A allows the following quantity measurements.
Simultaneous measurements of all items with selected time weighting and frequency
characteristics.
Sound level Lp
Equivalent continuous sound Leg
Sound exposure level SEL
Maximum sound level Lmax
Minimum sound level Lmin
Percentile sound level LN (L05, L50, L90, L95) calculated from Lp
Frequency rating A, C, Z
Time weighting
Main Channel Fast, Slow, 10ms, impulse
Sub Channel Fast, Slow, 10ms, impulse
Safety Symbol: Complies with EMC

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2. Descriptions
2.1 Meter Description
Refer to the diagram below for the following descriptions.
1. Windscreen
2. Microphone
3. Display
4. Operation keys
5. 6VDC adapter jack
6. DC analog output jack
7. AC analog output jack
8. Comparator output jack
9. Trig IN jack
10. Micro SD card slot
11. Power switch
12. Hand strap
13. USB port
14. Battery compartment
15. Tripod mounting screw

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2.2 Operation Buttons
START/STOP button
Press to start or stop for recording the sound pressure measurement.
PAUSE/CONT button
Press to temporarily pause ( ) a measurement) or resume () measurement.
M button
Press to scroll through and select different processing modes.
LEVEL 
Press to select the level range for measurement. The following five settings are available.
20 to 90 dB, 20 to 100 dB, 20 to 110 dB, 30 to 120 dB, 40 to 130 dB.
GRP/ NUM button
Press to switch between graph and numeric display for Octave measurements.
SLM 1/1 1/3 button
Press to switch to select the sound level meter display and analysis screen.
(SLM, 1/1, 1/3, 1/1&1/3)
MENU
Press to enter menu screen to setup various menu parameters. Press again to close the
menu.
R button
Start or stop the auto Record process or press to manually store the measurement data

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into memory.
/ 
Press to move the octave frequency band marker during frequency analysis.

+
/

-
Press to select and set items in various menu screens. Holding the buttons down will cause
faster scrolling.
FREQ WEIGHT TIME button
The FREQ WEIGHT selects the frequency weighting for the main channel. “A” weighting (A),
“C” weighting (C), and flat frequency response (Z).
The TIME WEIGHT selects the time weighting function for the main channel. (F, S, 10ms, I)
Fast: 125ms; Slow: 1000ms; 10ms; Impulse: 35ms
Note: The frequency and time weighting for the sub channel can be selected by accessing
the menu screen.
button (Backlight/Enter)
Backlight powers on the display backlight. Press the button again to turn backlight off.
When automatic Backlight Off function is selected from the menu screen, the backlight will
turn itself off automatically after the preset time.
Enter button will finalize a setting of an item in a menu or any other setting.

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2.3 Display Screen
1. Mode of analysis: Indicates the condition of the display screen.
SLM: Sound level meter display
1/1 OCT: Octave band analysis screen
1/3 OCT: 1/3 Octave band analysis screen
1/1 and 1/3 OCT: Simultaneous octave and 1/3 octave band analysis screen
2. Measurement in progress: When a measurement recording is in progress or during auto store
the symbol flashes. During measurement pause the symbol is displayed on the screen.
3. USB Link Status: Shows if the USB is enabled or disabled.
4. Trigger Mode: Controls the measurement and memory auto store start behavior. Available
modes are: Level 1 (LV1), Level 2 (LV2), EXT (EXT), and time (TIME).
5. Elapsed Time: Displays the elapsed time in seconds during processing and storing memory.
6. Memory: Displays the selected memory for storing data.
FL: The data will be stored in the internal memory of the meter.
Sd: The data will be stored on the micro SD card
Mode of analysis
Measurement in progress symbol
USB link status
Trigger mode
Elapsed time
Memory
Store mode
Address
Level range
Overloadindication
Subchannelleveldisplay
Sub channel
Time weighting
Frequencyweighting
Current time
Current date
Comparator ON
Auto store full indication
Manual store full indication
Power
status
Mainchannellevel
display
Time weighting
Main channel
Frequencyweighting
Underrangeindication
Bar graph