Virtins Vt rta-268a User manual

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

VT RTA-268A/B/C Manual

An Ultra Low-Noise Real Time Acoustic Analyzer, Sound Level Meter,

Distortion Analyzer, Polarity Tester, Time Delay Finder …

Note: VIRTINS TECHNOLOGY reserves the right to make modifications to this manual at any time without

notice. This manual may contain typographical errors.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

TABLE OF CONTENTS

1 INSTALLATION AND QUICK START GUIDE..........................................................................................3

1.1 PACKAGE CONTENTS....................................................................................................................................3

1.1.1 Standard Package ................................................................................................................................3

1.1.2 Optional Items......................................................................................................................................4

1.2 HARDWARE CONNECTION ............................................................................................................................5

1.3 HARDWARE DRIVER INSTALLATION.............................................................................................................6

1.4 MULTI-INSTRUMENT SOFTWARE INSTALLATION AND CONFIGURATION.......................................................6

1.4.1 Install Multi-Instrument.......................................................................................................................6

1.4.2 Start Multi-Instrument..........................................................................................................................6

1.4.3 Configure Multi-Instrument .................................................................................................................8

1.5 INPUT OF SOUND LEVEL CALIBRATION DATA ............................................................................................13

1.5.1 0dB Reference Vr...............................................................................................................................14

1.6 MICROPHONE FREQUENCY COMPENSATION ...............................................................................................15

1.7TWENTY MOST FREQUENTLY USED MEASUREMENT SETTINGS .................................................................17

1.8 MORE ACOUSTIC ANALYSIS FUNCTIONS AVAILABLE IN MULTI-INSTRUMENT PRO OR ABOVE..................21

1.9 LIST OF AUDIO TEST WAV FILES (AUDIOTESTCD.ZIP) .............................................................................21

1.10 OPERATION NOTES ...................................................................................................................................23

1.11 UAC-232 CONTROL PANEL......................................................................................................................23

1.12 UAC-232 MIX CONTROL..........................................................................................................................24

1.13 TIME DELAY MEASUREMENT ...................................................................................................................25

1.13.1 Two-channel Time Delay Measurement using Cross Correlation ...................................................25

1.13.2 Single-channel Time Delay Measurement using Auto Correlation..................................................26

1.13.3 Single-Channel Time Delay Measurement using Pulse Emission....................................................27

1.14 AUDIO AND ULTRASOUND ANALYSIS.......................................................................................................27

2 SPECIFICATIONS.........................................................................................................................................28

2.1 VT RTA-268A/B/C HARDWARE CONFIGURATION.....................................................................................28

2.2 OVERALL VT RTA-268A/B/C SPECIFICATIONS.........................................................................................28

2.3 UAC-232 AUDIO INTERFACE SPECIFICATIONS...........................................................................................28

2.4 MEASUREMENT MICROPHONE M215 SPECIFICATIONS (FOR VT RTA-268A).............................................30

2.5 MEASUREMENT MICROPHONE M215L SPECIFICATIONS (FOR VT RTA-268B) ..........................................31

2.6 MEASUREMENT MICROPHONE M50 SPECIFICATIONS (FOR VT RTA-268C)...............................................32

2.7 MULTI-INSTRUMENT SOFTWARE SPECIFICATIONS......................................................................................33

3 MULTI-INSTRUMENT SOFTWARE LICENSE INFORMATION ........................................................42

3.1 LICENSE TYPES...........................................................................................................................................42

3.2 LICENSE UPGRADE FROM ONE LEVEL TO ANOTHER...................................................................................42

3.3 SOFTWARE UPGRADE IN THE SAME LICENSE LEVEL...................................................................................42

4 WARRANTY...................................................................................................................................................42

5 DISCLAIMER.................................................................................................................................................43

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

1 Installation and Quick Start Guide

VT RTA-268A/B/C is a series of PC-based ultra-low-noise real-time acoustic analyzers,

audio interface used in the analyzers has two ADCs working in tandem to create a single

output data stream in 32-bit float format. One “low gain” ADC is optimized for high-level

signals, and the other “high gain” ADC is optimized for low-level signals. This state of the

art dual-ADC architecture provides an unmatchable dynamic range compared with the

conventional single ADC approach. With a proper microphone, it is now possible to capture

sound across the entire human hearing range without sacrificing fidelity at low signal levels

or encountering clipping at high signal levels, and this can be achieved without the hassle of

manual analog gain adjustment.

1.1 Package Contents

1.1.1 Standard Package

A standard VT RTA-268A/B/C Package contains the following items:

1) XLR Measurement microphone and its accessories (a windshield, a microphone clip and

stand)

2) XLR-to-USB Audio Interface

3) USB Cable (1 m)

4) XLR Cable (1.5 m)

XLR Measurement Microphone

Windshield

Microphone Clip and Stand

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

5) CD (containing the copy-protected Multi-Instrument software)

The latest software can always be downloaded from www.virtins.com/MIsetup.exe.

6) USB hardkey (containing a Multi-Instrument Pro license)

7) Audio Test WAV files (containing a list of audio test tones and noises)

They can be downloaded at: www.virtins.com/AudioTestCD.zip and then burnt into a CD

or saved into a USB memory stick. They can also be generated directly from the Signal

Generator of Multi-Instrument.

8) Carrying Case

9) Unique Sound Level Calibration Data (in CD)

10)Unique Microphone Calibration Data (in CD, only applicable to RTA-268C)

1.1.2 Optional Items

1) An additional XLR measurement microphone and its accessories

2) P48-to-IEPE converter (so that IEPE sensors can be connected to the XLR input)

3) IEPE sensors

4) Software license upgrade

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

1.2 Hardware Connection

Sound Measurement

Connect the XLR measurement microphone to the input jack 1 of the audio interface.

Connect the corresponding ends of the USB cable to the XLR-to-USB Audio interface and a

PC’s USB port. When this is complete, the blue LED at the top right corner of the front panel

lights up, indicating that it is receiving power.

Then switch on the 48V phantom power of input jack 1. This is required by the condenser

measurement microphone used here, meanwhile, the Guitar/Bass switch for HiZ support

MUST be turned off.

Software Activation

The USB hardkey needs to be plugged into any USB port of the PC in order to activate the

Multi-Instrument software. Otherwise the software will run under the 21-day fully functional

free trial mode before the trial period expires.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

Test Signal Generation

You can generate the test signals from the Signal Generator of Multi-Instrument. The XLR-

to-USB audio interface has two ¼-inch TRS jacks on its back panel, respectively for left and

right balanced line-level outputs, and a ¼-inch TRS stereo headphone jack on its front panel.

The test signals output from these jacks can be fed into the audio system under test.

Alternatively, you can play the test signals from an audio CD or a memory stick.

1.3 Hardware Driver Installation

The device driver installer RTA268ABC_DriverInstaller.exe is located in the

Drivers\VTRTA268ABC directory in the CD. When you install the Multi-Instrument

software, a copy of the device driver installer will also be installed in the software installation

directory\Drivers\VTRTA268ABC. Run it to install the driver. After driver installation, the

device will be supported by both Sound Card MME and ASIO drivers in Multi-Instrument.

1.4 Multi-Instrument Software Installation and Configuration

Multi-Instrument is a powerful multi-function virtual instrument software. It supports a

variety of hardware ranging from sound cards which are available in almost all computers to

proprietary ADC and DAC hardware such as NI DAQmx cards, VT DSOs and so on. It

consists of multiple test instruments such Oscilloscope, Spectrum Analyzer, and Multimeter,

etc.

1.4.1 Install Multi-Instrument

Insert the Multi-Instrument installation CD into your computer’s CD-ROM drive and follow

the instruction on the screen to install the Multi-Instrument software. The installation file

can also be downloaded from www.virtins.com/MIsetup.exe.

1.4.2 Start Multi-Instrument

To start Multi-Instrument, on the Windows desktop, select [Start]>[All Programs]>[Multi-

Instrument]>[VIRTINS Multi-Instrument], or simply double click the MI icon.

If the software is started for the very first time after installation, it will prompt the user to

select a default device (see figure below). Select VT RTA-268A/B/C according to the

hardware device to be used.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

The default device can also be changed later via [Setting]>[ADC Device], [Setting]>[DAC

Device], and [Setting]>[Configure Hot Panel Setting Toolbar], or simply [Setting]>[Restore

to Factory Default]. However, if [Restore to Factory Default] command is executed, all

calibration data entered manually via [Setting]>[Calibration] after software installation

will be reset to the default values of the selected product. To avoid the loss of the

manually entered calibration data, you can save them as a calibration file first.

Otherwise, you will have to enter the unique calibration data that come with the

product package again.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

In case the driver has not yet been installed, the software will prompt the user to install the

driver. Restarting program is required after that.

After the default device is selected, the software will prompt the user to select a default color

scheme (Skin). The default skin can also be changed later via [Setting]>[Display].

The main window of the software will open after the above skin selection. The following

figure shows a typical screen layout (obtained by clicking the “OCT3” button in the Hot

Panel Setting Toolbar after the launch of the software). Please refer to the software manual

for detailed functions of the software. The software manual can be accessed via [Start]>[All

Programs]>[Multi-Instrument]>[VIRTINS Multi-Instrument Manual] (in PDF format) or

[VIRTINS Multi-Instrument Help] (in HTML format) on Windows Start menu, or

[Help]>[Software Manual] or F1 inside the software.

1.4.3 Configure Multi-Instrument

In Multi-Instrument, the menu items are enabled / disabled based on context. Many menu

items are disabled when the Oscilloscope or the Signal Generator is running. To do the

configuration, stop the oscilloscope first by pressing the green button at the upper left corner

of the screen (see figure below). The button will turn red once the Oscilloscope is stopped.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

1.4.3.1 Configure Sound Recording Devices for Multi-Instrument

The audio interface can be used with either MME or ASIO driver. ASIO driver is

recommended as it uses the sampling rate selected in Multi-Instrument directly and bypasses

the possible sampling rate conversion and audio signal enhancement by Windows, which

may otherwise alter the original samples and lead to measurement inaccuracies.

1.4.3.1.1 Using ASIO Driver

Go to [Setting]>[ADC Device], and select “Sound Card ASIO”in the “Device Model”field.

Then choose “ZOOM UAC-232 ASIO Driver” in the “Device No.” field (see figure below).

This is to configure the audio interface as the sound recording device for the software.

Click the “Control Panel”button to bring up the control panel for the audio interface (see

figure below).

1.4.3.1.1.1 Buffer Size

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

There is generally no need to change the default Buffer Size for test and measurement

applications. A large buffer size is preferred, though.

1.4.3.1.1.2 Sampling Rate

Under ASIO, the Sampling Rate will be set directly in Multi-Instrument and thus changing it

here will have no effect. Instead, the Sampling Rate here will passively follow what is set in

Multi-Instrument.

On the other hand, if MME is used instead, you can only change the actual sampling rate of

the audio interface here. The change here will be reflected in the sampling rate displayed in

the Sound Recording Tab under the Windows Control Panel. When the sampling rate set in

Multi-Instrument differs from the one here, Windows will conduct sampling rate conversion

automatically.

1.4.3.1.1.3 Format

Two formats are supported by the audio interface: 24-bit (Integer) or 32-bit Float. One

unique feature of the audio interface is its support for 32-bit float format. This format

provides much finer resolution than the 24-bit (Integer) format when the signal is weak,

thanks to the audio interface’s state of the art dual-ADC architecture, with one optimized for

weak signals and the other optimized for strong ones. Both formats have the same resolution

when the signal is strong. It is thus recommended to use the 32-bit float format for sound

recording (ADC). However, currently its ASIO driver does not support 32-bit float format

for signal output (DAC). Hence, MME should be used for sound playback (DAC) instead.

When the 32-bit float format is used, the Sampling Bit Resolution in Multi-Instrument must

be set to 32-bit, otherwise, an error message will pop up. When the ADC is running in the

32-bit float mode, the “32-Bit FLOAT”sign on the front panel of the audio interface will be

lit up, and “Float32”will be displayed at the middle bottom of the Oscilloscope window in

Multi-Instrument.

Now, if you start the oscilloscope by pressing the red button at the upper left corner of the

screen, and then talk before the measurement microphone, you should be able to see your

“voices” in the Oscilloscope and Spectrum Analyzer.

1.4.3.1.2 Using MME Driver

Go to [Setting]>[ADC Device], and select “Sound Card MME”in the “Device Model”field.

Then choose “Line (ZOOM UAC-232 Audio)” in the “Device No.” field (see figure below).

This is to configure the audio interface as the sound recording device for the software.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

Note that the displayed name of the audio interface may vary a bit under different Windows

versions or with different USB ports.

Now, if you start the oscilloscope by pressing the red button at the upper left corner of the

screen, and then talk before the measurement microphone, you should be able to see your

“voices” in the Oscilloscope and Spectrum Analyzer.

Note that MME does not support 32-bit float format.

1.4.3.2 Configure Sound Playback Devices for Multi-Instrument

The audio interface has left and right balanced line-level outputs and a stereo headphone

output. You can use the Signal Generator in Multi-Instrument to generate the test signals

through them.

If ASIO with 32-bit float format (recommended) is used for sound recording (ADC), MME

must be chosen for sound playback (DAC). To do that, go to [Setting]>[DAC Device], and

select “Sound Card MME”in the “Device Model”field and “Line (ZOOM UAC-232

Audio)”in the “Device No.” field (see figure below).

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

If ASIO with 24-bit format is used for sound recording (ADC), ASIO must be chosen for

sound playback (DAC). To do that, go to [Setting]>[DAC Device], and select “Sound Card

ASIO”in the “Device Model”field and “ZOOM UAC-232 ASIO Driver”in the “Device

No.” field (see figure below).

If MME is used for sound recording (ADC), then MME must be chosen for sound playback

(DAC).

Now, if you press the Signal Generator button (see figure above), the Signal Generator panel

will be opened (see figure below). Press the red triangle button at the upper right corner of

the Signal Generator panel, you should hear a 1kHz test tone from the speaker or earphone

connected to the audio interface. Press it again to stop the sound.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

1.5 Input of Sound Level Calibration Data

Sound Level Calibration is not required for those relative measurements such as frequency

response, THD, THD+N, IMD, etc.. It is required only if you want to measure the absolute

sound level.

Please refer to the calibration data sheet provided in the product package and enter the

calibration data in the respective highlighted fields in the Calibration Setting dialog box (see

figures below). The Calibration Setting dialog box can be opened via [Setting]>[Calibration]

in Multi-Instrument. Note that the “0dB Reference Vr”calibration data in the following

figure are examples only. You should enter the actual calibration data provided inside the

product package.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

The audio interface has an ultra-low noise level and offers a huge dynamic range of about

135dB, owing to its state of the art dual-ADC architecture. Consequently, the absence of

analog gain adjustment knobs on the audio interface panel is a deliberate design choice, as

the exceptional dynamic range eliminates the need for such adjustments.

The audio interface also comes with a piece of utility software called UAC-232 Mix Control

(see Section 1.12), where the digital gain of the input channels 1 & 2 can be adjusted from

0dB to 60dB. Please note that the calibration data are valid only when the digital gains

are set at 0dB. The digital gain should always be kept at 0dB in order not to invalidate the

calibration. Under the 32-bit float mode, the quality of the acquired data will not be affected

by the digital gain settings.

1.5.1 0dB Reference Vr

The “0dB Reference Vr”in the Calibration Setting dialog box is used to finally calibrate the

input voltage to dBSPL. The input voltage here should be considered as a relative value as

the actual input is not a voltage but a sound pressure. The “0dB Reference Vr”is the

parameter to be recalibrated if a sound level recalibration is necessary. To do the

recalibration, simply enter the actual sound level value into the “Actual Value”edit box and

the measured sound level value into the “Read Value”edit box, and then press the

“Calculate”button ONCE. It should be noted that the Sensor Sensitivity is kept at 1V/V in

this method.

In case you want to display the measured raw data in Pa rather than Volt, then you should

enter the “actual”Sensor Sensitivity in V/Pa, which can be calculated using the following

formula:

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

Sensitivity = [“0dB Reference Vr”(in Volt)] / [Standard 0dB Reference (in Pa)]

where the Standard 0dB Reference for sound pressure level in air is 20 µPa (i.e. 2e-005 Pa)

and that in water is 1 µPa (i.e. 1e-006 Pa). If the “actual”Sensor Sensitivity is used, then the

standard 0dB reference should be entered into the “0dB Reference Vr”edit box. For

example, the following two methods are equivalent.

Method 1: [0dB Reference Vr] = 8e-007 (V) and [Sensor Sensitivity] = 1 V/V

Method 2: [0dB Reference Vr] = 2.0e-005 (Pa) and [Sensor Sensitivity] = 0.04 V/Pa

1.6 Microphone Frequency Compensation

The measurement microphones in RTA-268 series have extremely flat frequency responses

in the audio frequency range. Generally, there is no need to compensate for the microphone

frequency response. However, a higher degree of accuracy can be achieved if the

microphone comes with a frequency response file or a frequency compensation file. The

difference between these two files is the sign of the gain values (in dB). For example, a gain

of 3dB in a frequency response file should have a gain of -3dB in its equivalent frequency

compensation file.

The XLR measurement microphone in RTA-268C comes with an individually calibrated

Original Frequency Response File RTA-268C.txt. “Original” means that it has exactly the

same format and contents as the calibration file provided by the microphone manufacturer.

This file is located in the CD directory “\Microphone Frequency Compensation File”.

Please copy this file to the “\fcf”directory under the installation directory of Multi-

instrument in the hard disk (if the file already exists, overwrite it), so that you can use it

later. This file is also used by the default panel settings configured in the Hot Panel Setting

Toolbar (The third toolbar from the top), except the buttons labelled “Ultrasound”, “TDac”,

“TDcc” and “TDgcc”.

You can load the Original Frequency Response File by right clicking anywhere within the

Spectrum Analyzer window, selecting [Spectrum Analyzer Processing]> “Intra-Frame

Processing”> “Compensation 1”, changing the “Files of type”from “Frequency

Compensation File (*.fcf)”to “Original Frequency Response File (*.txt)”in the pop-up File

Open dialog box, and loading that file (see figures below). If you want to apply it to the

twenty most frequently used panel settings in the Hot Panel Setting Toolbar, you will need to

configure and save the corresponding panel setting files one by one. Luckily, this has already

been done for the default panel settings.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

Some Windows versions / editions come with some audio signal enhancement features which

are enabled by default. These features must be disabled through the Sound Recording Control

under Windows Control Panel to prevent them from altering the originally sampled data, as

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

shown below. One of the possible problems caused by these features is the unwanted

alteration of the frequency response of the setup. Using ASIO driver instead of MME driver

can avoid these problems.

1.7 Twenty Most Frequently Used Measurement Settings

Multi-Instrument bundled with VT RTA-268A/B/C comes with many pre-configured panel

setting files. This saves you time in configuring various parameters for some frequently

performed measurements by yourself. You can load these panel setting files via

[Setting]>[Load Panel Setting]. Furthermore, 20 most frequently used panel setting files are

pre-configured in the Hot Panel Setting Toolbar (The third toolbar from the top). You can

load one of them by a single mouse click. These 20 measurement settings are:

(1) Home: Default Setting

The factory default panel setting. It is equivalent to the [File]>[New] command.

(2) OCT3spl: 1/3 Octave Analysis (Avg. 10) in SPL

Pink noise will be generated by pressing the start button of the Signal Generator. The pink

noise will be injected into the DUT (Device Under Test), and the response of the DUT will

be captured and analyzed by the Oscilloscope and Spectrum Analyzer. A flat curve in the

Spectrum Analyzer would indicate a flat magnitude frequency response of the DUT. The

equivalent continuous sound level in dB will be displayed in the Multimeter window.

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

(3) OCT3ppn: 1/3 Octave Analysis

Same as OCT3spl, but periodic pink noise instead of ordinary (non-periodic) pink noise is

used as the stimulus. One advantage of using periodic pink noise is that its spectrum is

ideally flat under octave analysis even without inter-frame averaging. Also, the Y axis is

displayed in dBFS instead of dBSPL in Spectrum Analyzer.

(4) Polarity: Speaker, Microphone, Amplifier Polarity Tester with Crest Factor Check

A polarity test signal will be generated by pressing the start button of the Signal Generator.

Point the microphone close to the center of the speaker under test along its axis, and observe

the polarity of the captured pulse in the oscilloscope window. If the pulse goes positive

initially, then the polarity of the speaker under test is positive, and vice versa.

Positive Negative

(5)

RT60pn: Reverberation Analysis via Interrupted Noise (1/1 Octave Band) (applicable to VT

RTA-268A/B)

Pink noise will be generated for 5 seconds only by pressing the start button of the Signal

Generator. It will be projected into the enclosure under test. After about 4.5 seconds, the

Oscilloscope will be started automatically by the software under the “Sync. No Loopback”

mode of the Signal Generator. This is to capture the last 0.5 second of the emitted pink noise

and 4.5 seconds of its subsequent decay process. The data analysis may take quite a long

time. Please be patient! The measured RT20 value in each 1/1 octave band as well as its

overall value will be displayed. RT30 can also be displayed if needed. Please refer to the

sections for Reverberation in the software manual for details.

Ultrasound: Audio and Ultrasound Analysis (applicable to VT RTA-268C)

Unlike other pre-configured panel settings in this toolbar, the microphone frequency response

file RTA-268C.txt is not configured in the Spectrum Analyzer in order to allow for a much

wider frequency range, which is theoretically from 0 to 96 kHz.

(6) RT60imp: Reverberation & Speech Intelligibility Analysis via Impulse Response (1/1

Octave Band)

Reverberation and Speech intelligibility analysis will be performed based on Impulse

Response Schroeder Integration. The impulse response can be obtained through direct

methods (such as a gunshot) or indirect methods (such as transfer function measurement).

The data analysis may take quite a long time. Please be patient! Please refer to the

sections for Reverberation and Speech Intelligibility in the software manual for details.

(7) THDcd: THD,THD+N,SNR,SINAD,Noise Level, ENOB (Avg. 10 )

A 1 kHz sine wave will be generated by pressing the start button of the Signal Generator. The

sine wave will be injected into the DUT (Device Under Test), and the response of the DUT

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

will be captured and analyzed by the Oscilloscope and Spectrum Analyzer. All the above

parameters of the DUT will be measured and displayed. This panel setting should be used if

different sound cards are used for signal input and output. It should also be used if the 1 kHz

test tone is played from an audio CD or a memory stick.

(8) IMDsmp: IMD SMPTE (60 Hz + 7 kHz, 4:1) (Avg. 10)

A 60 Hz and a 7 kHz sine waves mixed at an amplitude ratio of 4:1 will be generated by

pressing the start button of the Signal Generator. The mixed signals will be injected into the

DUT (Device Under Test), and the response of the DUT will be captured and analyzed by the

Oscilloscope and Spectrum Analyzer. The SMPTE IMD value of the DUT will be measured

and displayed.

(9) IMDdin: IMD DIN (250 Hz + 8 kHz, 4:1) (Avg. 10)

A 250 Hz and an 8 kHz sine waves mixed at an amplitude ratio of 4:1 will be generated by

pressing the start button of the Signal Generator. The mixed signal will be injected into the

DUT (Device Under Test), and the response of the DUT will be captured and analyzed by the

Oscilloscope and Spectrum Analyzer. The DIN IMD value of the DUT will be measured and

displayed.

(10) IMDccif: IMD CCIF2 (19 kHz + 20 kHz, 1:1) (Avg. 10)

A 19 kHz and a 20 kHz sine waves mixed at an amplitude ratio of 1:1 will be generated by

pressing the start button of the Signal Generator. The mixed signal will be injected into the

DUT (Device Under Test), and the response of the DUT will be captured and analyzed by the

Oscilloscope and Spectrum Analyzer. The CCIF2 IMD value of the DUT will be measured

and displayed.

(11) FRwhite: Magnitude Frequency Response (White Noise, Avg. 30)

White noise will be generated by pressing the start button of the Signal Generator. The white

noise will be injected into the DUT (Device Under Test), and the response of the DUT will

be captured and analyzed by the Oscilloscope and Spectrum Analyzer. The curve in the

Spectrum Analyzer indicates the magnitude frequency response of the DUT.

(12) FRpwn: Magnitude Frequency Response (Periodic White Noise)

Periodic white noise will be generated by pressing the start button of the Signal Generator.

The periodic white noise will be injected into the DUT (Device Under Test), and the

response of the DUT will be captured and analyzed by the Oscilloscope and Spectrum

Analyzer. The curve in the Spectrum Analyzer indicates the magnitude frequency response

of the DUT. One advantage of using periodic white noise is that its spectrum is ideally flat

even without inter-frame averaging.

(13) FRswLin: Magnitude Frequency Response (Frequency Sweep, Linear)

A 0.68266667-second 20Hz-to-20kHz linear frequency swept sine wave will be generated by

pressing the start button of the Signal Generator. The signal will be injected into the DUT

(Device Under Test), and the response of the DUT will be captured by the Oscilloscope and

Spectrum Analyzer. The curve in the Spectrum Analyzer indicates the magnitude frequency

response of the DUT. Note that you will need to adjust the trigger level so that the

Oscilloscope will be triggered just upon the start of the sweep.

(14) FRswLog: Magnitude Frequency Response (Frequency Sweep, Log)

VT RTA-268A/B/C Manual Rev. 1.5

Virtins Technology

A 0.68266667-second 20Hz-to-20kHz logarithmic frequency swept sine wave will be

generated by pressing the start button of the Signal Generator. The signal will be injected into

the DUT (Device Under Test), and the response of the DUT will be captured by the

Oscilloscope and Spectrum Analyzer. The curve in the Spectrum Analyzer indicates the

magnitude frequency response of the DUT. Note that you will need to adjust the trigger level

so that the Oscilloscope will be triggered just upon the start of the sweep.

(15) FRmt: Magnitude Frequency Response (MultiTone, 31 1/3 Octave Bands)

A multitone consists of 31 1/3 octave band center frequencies from 20 Hz to 20kHz will be

generated by pressing the start button of the Signal Generator. The signal will be injected into

the DUT (Device Under Test), and the response of the DUT will be captured by the

Oscilloscope and Spectrum Analyzer. The curve in the Spectrum Analyzer indicates the

magnitude frequency response of the DUT.

(16)sLeq: Short Equivalent Continuous Sound Level (Short Leq, 125ms)

This panel setting will display the short equivalent continuous sound level. The value is time-

averaged over continuous 125 ms.

(17)sLeqA: Short Equivalent Continuous Sound Level (Short Leq, 125ms) (A-Weighted)

This panel setting will display the A-weighted short equivalent continuous sound level. The

value is time-averaged over continuous 125 ms.

(18)TDac: Single-Channel Time Delay Measurement via Auto Correlation

White noise will be generated from Output Ch.A by pressing the start button of the Signal

Generator. The superimposed direct and reflected signals from Input Ch.A will be captured

and analyzed by the Oscilloscope and Spectrum Analyzer. The time delay between them will

be measured by locating the second highest auto correlation peak along the time axis. The

corresponding auto correlation coefficient will also be displayed. A positive coefficient

indicates that the superimposed two signals are positively correlated and vice versa. A

deadband of 0.25ms is configured in [Spectrum Analyzer Processing] by default to enforce a

minimum interval between the first and second highest auto correlation peaks in order to

avoid false peak identification.

(19)TDcc: Dual-Channel Time Delay Measurement via Cross Correction (oB->iB)

White noise will be generated from Output Ch.B by pressing the start button of the Signal

Generator. The signals from Input Ch.A and Ch.B will be captured and analyzed by the

Oscilloscope and Spectrum Analyzer. The time delay between them will be measured by

locating the highest cross correlation peak along the time axis. The corresponding cross

correlation coefficient will also be displayed. A positive coefficient indicates the two signals

are positively correlated and vice versa. The signal fed to Input Ch.B can also be a loopback

signal from Output Ch.B. If that is the case, it is assumed that the loopback is done through

UAC-232 Mix Control without any external connection. The Output Ch.A is set to NONE to

cut off the loopback from Output Ch.A to Input Ch.A. The test signal will be output from

Output Ch.B only. This loopback method introduces a system lag that is a function of

sampling rate (e.g. 625μs@48kHz, 250μs@192kHz). It can be removed from the measured

time delay using UDDP (User Defined Data Point). This corrected time delay will also be

shown.

(20)TDgcc: Dual-Channel Time Delay Measurement via Generalized Cross Correction

(oB->iB)

This manual suits for next models

Table of contents

Other VIRTINS Measuring Instrument manuals

VIRTINS

VIRTINS VT RTA-168A/B User manual

Popular Measuring Instrument manuals by other brands

UEi

UEi DL389B instruction manual

Zebra-Tech

Zebra-Tech MEASURING BOARD Operation manual

Hanna Instruments

Hanna Instruments HI99151 instruction manual

Endress+Hauser

Endress+Hauser Waterpilot FMX21 operating instructions

Sonel

Sonel CMP-1015-PV user manual

Endress+Hauser

Endress+Hauser Cerabar M operating instructions

STAUFF

STAUFF PPC-06 operating instructions

HT Instruments

HT Instruments HT4011 user manual

ATIM

ATIM ACW/SF8-WL-I user guide

Vega

Vega VEGAPULS 66 enamel operating instructions

Metsys

Metsys ML3 manual

KPFM

KPFM X2 user manual

Tektronix

Tektronix TDSUSB2 manual

palintest

palintest Lumiso Pooltest Expert quick start guide

BROWIN

BROWIN 405570 Nstructions for use

AquaLabo

AquaLabo CORAIL user guide

elsner elektronik

elsner elektronik KNX eTR M1 Technical specifications and installation instructions

Omega

Omega Volume VII-System Description Operation manual

VIRTINS VT RTA-268A User manual

Popular Measuring Instrument manuals by other brands