DAB/DAB+/DMB Receiver Test Solution

Application Note

Using National Instruments PXI Vector Signal Generators, Vector Signal

Transceivers and MaxEye DAB/DAB+/T-DMB Signal Generation Software

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Contents 1. Introduction ............................................................................................................................. 3

2. Test System Hardware and Software Requirements ............................................................... 3

2.1. Test Setup ......................................................................................................................... 4

3. DAB/DAB+/T-DMB Signal Generation Software.................................................................. 5

3.1. Set up MaxEye DAB Signal Generation Software .......................................................... 6

4. Receiver Test Procedure ........................................................................................................ 10

4.1. Receiver Performance Tests ........................................................................................... 10

4.1.1 Sensitivity and Maximum Input Power Level Tests .................................................... 10

4.1.2 Receiver Performance in Multipath Fading Channel ................................................... 11

4.1.3 Receiver Selectivity Tests ............................................................................................ 15

4.1.4 Receiver Reacquisition Time........................................................................................ 16

4.2. Receiver Functionality Tests .......................................................................................... 17

5. MaxEye DAB/DAB+/DMB Toolkit API .............................................................................. 18

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1. Introduction

Digital Audio Broadcasting (DAB) is a digital radio technology for broadcasting radio stations,

used in several countries, particularly in Europe. The DAB family of standards includes DAB,

DAB+ for digital radio and DMB for mobile TV. They are flexible, global and open standards

and are a means for transmission of terrestrial digital radio signals.

When the original DAB (Digital Audio Broadcasting) was first developed in the late 1980s, it

was based on MPEG Audio Layer II coding, which is still commonly used in broadcasting today.

The integration of AAC into DAB allowed higher efficiency, meaning the same audio quality at

lower bitrates - hence the birth of DAB+. Another important innovation was the addition of

video/multimedia capabilities to Digital Audio Broadcasting, allowing DAB to become a digital

mobile television platform DMB (Digital Multimedia Broadcasting) as well as a multimedia

digital radio platform. Both for DMB and DAB+ the technical basis remains DAB.

This document describes the measurement configurations and procedures for DAB receiver

testing using National Instruments PXI Vector Signal Generators and MaxEye

DAB/DABPlus/T-DMB Signal Generation software.

2. Test System Hardware and Software Requirements

The following are the hardware and software requirements for the test setup.

Table 1 DAB, DAB+ and DMB Test Configuration

Product Name Model Number Options

NI PXI Chassis

8-Slot 3U PXI Express Chassis

NI PXIe-1082 -

NI PXI Controller

2.3 GHz Quad-Core PXI Express

Controller

NI PXIe-8135 4 GB Upgrade/Replacement RAM

for PXIe-8135

NI Vector Signal Generator NI PXIe-5671

NI PXIe-5672

NI PXIe-5673/5673E

NI PXIe-5644R/5645R/5646R

With 512MB RAM

NI RFSG driver version 1.7 or later

MaxEye DAB Signal Generation

Software

MAXEYE-MET-

DABTDMB_V001

-

NI LabVIEW 2011, 2012 and 2013

NI Modulation Toolkit Version 4.3 or later

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The MaxEye DAB Signal Generation software is available for free 30-days evaluation in

LabVIEW Tools Network. For more information about free evaluation of the MaxEye toolkit

please write to info@maxeyetech.com.

Download the software now from NI LabVIEW Tools Network and evaluate the software before

you purchase.

2.1. Test Setup

The diagram below shows the test setup using the hardware and software listed above. In the

diagram NI PXIe-5673E is used as a Vector Signal Generator. Please see the table above to see

the list of the other supported hardware.

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3. DAB/DAB+/T-DMB Signal Generation Software

The MaxEye DAB signal generation toolkit extends LabVIEW tools and functions with National

Instruments Vector Signal Generator to generate DAB/DAB+/DMB test signals that confirm to

the ETSI standard specifications for various standards. Table 2 gives the details of the standard

specifications for each of the supported standard.

The toolkit coding, modulation and other parameters can be easily configured using the

LabVIEW API VIs to generate custom waveform for specific test requirements.

NI PXIe-5673E

DAB/DAB+/DMB Receiver

BER

Receiver

Sensitivity

Channel Search

(Manual/Auto)

Search Results

Analysis

Channel

Up/down time

(Mute detection)

Audio/Video

Quality Analysis

TS Packet Analysis

EPG, Subtitles and

other Receiver

Functionality Tests

DAB Signal Generation

Figure 1 Test Setup for Receiver Performance and Functionality Tests

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Table 2 DAB/DAB+/DMB Standard Specifications

Sl.no Standard Name Specifications

1 DAB/DAB+/DMB ETSI EN 300 401 V1.4.1 (2006-06) - Radio Broadcasting

Systems; Digital Audio Broadcasting (DAB) to mobile,

portable and fixed receivers

ETSI TS 102 427 V1.1.1 (2005-07) - Digital Audio

Broadcasting (DAB); Data Broadcasting - MPEG-2 TS

streaming

ETSI TS 102 428 V1.1.1 (2005-06) - Digital Audio

Broadcasting (DAB); DMB video service; User Application

Specification

One of the significant feature of the toolkit is it allows storing the generated waveform in file and

then playing the waveform in realtime using NI RFSG Streaming mode. This feature enables

the testing of the received video/audio signals continuously for hours. The duration of the

generated waveform in this mode is limited only by the available disk memory.

The MaxEye Digital Video toolkit software provides support for MPEG 2 Transport streams as a

one of the payload option with complete channel coding and modulation to support the specific

needs of the design and verification of the digital video receivers, digital video transmitters and

their components. The software also supports other payload options like Test Patterns, User

Defined Bits, Binary file and PN Sequence. The toolkit coding, modulation and other parameters

can be easily configured using the Labview API Vis to generate custom waveform for specific

test requirements. The toolkit also supports adding impairments like AWGN, IQ impairments,

frequency and clock offsets to stress the receivers under real world conditions.

3.1. Set up MaxEye DAB Signal Generation Software

The following step by step procedure explains how to configure the signal generation software to

generate DAB/DAB+ and DMB signals.

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Steps Operations User Configuration and Software

Functionality

Open the

DAB Signal

Generation

Example

Open LabVIEW 2011 or higher version

Click Start > All Programs > MaxEye > Digital

Video Toolkits > DAB_TDMB > Generation

and open MaxEye DAB TDMB RFSG Signal

Generation.vi

Opens the front panel of the DAB signal

generation example

Configure

the

Hardware

Settings

Select Hardware Configuration Tab and configure

the following properties

Use the RFSG resource name

configured in the NI MAX software for

the VSG.

Configure Carrier Frequency, Power

Level, External Attenuation if used,

Headroom and Arbitrary waveform

generator pre-filter gain.

Configure the Headroom value

equivalent to the maximum expected

PAPR value of the signal. The default

value is 12dB

Configure

the DAB

Standard

specific

Global

Settings

Select Global Configuration Tab and configure the

following properties

DAB has a number of country specific

transmission modes (I, II, III and IV)

based on the frequency band. Select the

transmission mode.

Configure Number of Transmission

Frames to generate, this determines the

duration of the selected waveform

Select the Input mode, if the Input Mode

is ETI File the Service and Subchannel

configurations are read from the file. No

other user configuration is required.

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WorldDMB forum provides ETI Library

for the receiver testing.

WorldDMB ETI Library assists receiver

manufacturers in testing their products

ensuring they include the minimum set

of function requirements set out in the

WorldDMB Receiver Profiles, making

them compatible on a pan-European and

worldwide basis

If the Input Mode is user configuration

configure the Number of Services and

Subchannels and for each Subchannel

configure the Protection Mode,

Protection Level, Subchannel ID, UEP

Table Index and EEP n value.

Note: Standard uses two protection

methods, UEP – Unequal Error

Protection and EEP – Equal Error

Protection

Note: For BER measurements as per BS

EN 50248 specification, BER should e

measured in MSC using Equal Error

Protection with code rate of ½. For this

Protection Mode should be set to Long

Form and Protection Level should be

EEP-3A.

Configure

DAB

Service

Configurati

on Settings

Select the Service Configuration Tab and configure

the following properties. If the Input Mode is ETI

File skip this step.

Set Service Level configurations like

Service Reference number, Service

Label and Number of Service

components in each service.

For each service component configure

Transport Mechanism Id for DAB and

DAB+ select MSC-Stream Mode

(audio) for T-DMB select MSC-Stream

Mode (Data).

Select DABPlus as Audio Service

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Component Type for DABPlus mode.

Select the subchannel identifier of the

service component. Each subchannel

carries one service component.

For T-DMB mode set Data Service

Component Type as T-DMB.

Configure the Service component

Identifier and label.

Select the payload mode for DAB audio

test choose MPEG Layer II audio and

for DAB+ select MPEG4 HE AAC

Version 2.

For T-DMB testing select MPEG2TS

file. The other supported payload modes

are PN Sequence, User Defined Bits and

Test Pattern. Configure the remaining

properties based on the selected payload

mode and leave all other configurations

to default values.

Configure

Impairment

s

Select the Impairments Tab and configure the

following properties. If you are not adding

impairments in the signal skip this step.

Set Impairments Enabled? Property

value to True to enable adding

impairments in the signal.

Set AWGN Enabled Property to True to

enable adding simulated AWGN noise

to the signal. This is required for

receiver sensitivity measurements.

Configure the following properties

depending on the test requirement.

Carrier to Noise Ratio, Frequency

Offset, Clock Offset, I DC Offset, Q DC

Offset, IQ Gain Imbalance and

Quadrature Skew.

Note: For BER measurements as per BS

EN 50248 specification, BER should e

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measured in MSC using Equal Error

Protection with code rate of ½.

Configure

Multipath

fading

Select the Multipath Fading Tab and configure the

following properties. If you are not adding multipath

fading to the signal skip this step.

Configure the multipath properties

depending on the test requirement.

Run the

LabVIEW

example VI

The toolkit now generates the waveform if there is

no error in the user configuration. The errors

reported to the user for selecting the correct

configuration

4. Receiver Test Procedure

4.1. Receiver Performance Tests

4.1.1 Sensitivity and Maximum Input Power Level Tests

Sensitivity and Maximum input power level tests are two important BER tests used for testing

the minimum and maximum power level requirements of a DAB receiver.

As per the standard BS EN 62104:2007 Characteristics of DAB Receivers, the minimum

requirement is -81 dBm and the BER value should be less than or equal to 10-4

for both VHF and

L Band. The requirement for maximum input power is -10dBm, -15dBm, -20dBm respectively

for mobile, stationary and portable receivers in the VHF band. In the L-Band the maximum

power requirement is -25dBm.

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In some commercial receivers, there is no direct method of measuring the BER in this case we

need to use external BER measurement device. The test setup is shown in Figure 1 and suitable

attenuator can be used after the VSG to reduce the power for the sensitivity tests.

Test Procedure

1. Generate and save the waveform as per the steps given in section 3.1 of this document.

The recommended configuration for the BER test is

a. Protection Mode - Long Form

b. Protection Level - EEP-3A

c. Number of Subchannels – 1

d. Number of Services – 1

e. Number of service components in service - 1

2. Play the saved waveform using RFSG Play Waveform from file example.

3. Configure the carrier frequency and power level. Note: the sensitivity tests need to be

done on both VHF and L Band.

4. Generate the waveform and reduce the power level at the antenna input of the DAB

receiver by adding the external attenuator.

5. Reduce the power level till the BER reaches the value of 10-4

. Note down the power

level. Cable loss needs to be adjusted while computing the power level. Before the tests

calibrate the cable used for connecting the VSG and DAB receiver.

6. For maximum input power level test increase the power level till the BER reaches the

value of 10-4

. Note down this power level after adjusting for the cable loss.

4.1.2 Receiver Performance in Multipath Fading Channel

DAB receivers are designed to work in a mobile environment and there are three types of

channel profiles defined in BS EN 50248 standard for testing the receiver performance in a

Rayleigh channel. The channel profiles are defined for rural areas, urban areas and

SFN networks.

The test procedure is similar to the receiver sensitivity tests expect that we need to add multipath

channel fading as per the Table 2, 3 and 4 for the respective tests.

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Test Procedure

1. The recommended configuration for the BER test is

a. Protection Mode - Long Form

b. Protection Level - EEP-3A

c. Number of Subchannels – 1

d. Number of Services – 1

e. Number of service components in service – 1

2. Configure the multipath signal parameters as per the channel profile in Table 3, 4 and 5.

3. Generate and save the waveform in file.

4. Play the saved waveform using RFSG Play Waveform from file example.

5. Configure the carrier frequency and power level. Note: this tests need to be done on both

VHF and L Band.

6. Generate the waveform and reduce the power level at the antenna input of the DAB

receiver by adding the external attenuator.

7. Reduce the power level till the BER reaches the value of 10-4

. Note down the power

level. Cable loss needs to be adjusted while computing the power level. Before the tests

calibrate the cable used for connecting the VSG and DAB receiver.

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8. If the recorded power level is lesser than -75dBm than the DAB receiver passes the test

for this channel profile, carrier frequency and transmission mode.

Table 3 Typical Rural – Channel Profile

Path Number Path Gain (dB) Path Delay (us) Fading Type

4 Paths

1 0 0 Rician

2 -2 0.2 Rayleigh

3 -10 0.4 Rayleigh

4 -20 0.6 Rayleigh

6 Paths

1 0 0 Rician

2 -4 0.1 Rayleigh

3 -8 0.2 Rayleigh

4 -12 0.3 Rayleigh

5 -16 0.4 Rayleigh

6 -20 0.5 Rayleigh

Table 4 Typical Urban - Channel Profile

Path Number Path Gain (dB) Path Delay (us) Fading Type

6 Paths

1 -3 0 Rayleigh

2 0 0.2 Rayleigh

3 -2 0.5 Rayleigh

4 -6 1.6 Rayleigh

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5 -8 2.3 Rayleigh

6 -10 5.0 Rayleigh

12 Paths

1 -4 0 Rayleigh

2 -3 0.1 Rayleigh

3 0 0.3 Rayleigh

4 -2.6 0.5 Rayleigh

5 -3 0.8 Rayleigh

6 -5 1.1 Rayleigh

7 -7 1.3 Rayleigh

8 -5 1.7 Rayleigh

9 -6.5 2.3 Rayleigh

10 -8.6 3.1 Rayleigh

11 -11 3.2 Rayleigh

12 -10 5.0 Rayleigh

Table 5 SFN Networks - Channel Profile for VHF Band

Path Number Path Gain (dB) Path Delay (us) Fading Type

1 0 0 Rayleigh

2 -13 100 Rayleigh

3 -18 220 Rayleigh

4 -22 290 Rayleigh

5 -26 385 Rayleigh

6 -31 480 Rayleigh

7 -32 600 Rayleigh

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4.1.3 Receiver Selectivity Tests

Receiver Selectivity determines the ability of a receiver to receive a wanted signal when strong

unwanted signal is present in the channel adjacent to the wanted frequency.

EN 62104:2007 presents two types of selectivity measurements, adjacent channel selectivity and

Far-off channel selectivity. The difference between the test procedures for the two tests is for the

adjacent channel selectivity DAB signal is used as interferer and for Far-off selectivity test FM

modulated signal is used as interferer.

For the adjacent channel measurement both the wanted and unwanted signals are DAB signals

separated by 1.712 MHz and for the far-off selectivity measurement the unwanted signal is FM

NI VSG 5673E

NI VSG 5673E

DAB/DAB+/DMB Receiver

DAB Signal Generation

DAB Signal Generation

Figure 2 Test Setup for Selectivity Measurement

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modulated signal with center frequency equal to or higher than 5 MHz from the center frequency

of the wanted DAB signal.

The selectivity of the DAB receiver is measured as

Selectivity = Punwanted - Pwanted

Test Procedure

1. Generate and save the waveforms in file for both wanted and unwanted DAB signals.

2. Play the DAB waveform files in both the Vector Signal Generators for adjacent channel

selectivity test and for far-off selectivity test in the second Vector Signal Generator

generate FM modulated waveform.

3. Configure the frequency of the wanted and unwanted signals center frequency in VSG1

and VSG2 respectively.

4. Configure the power level of the wanted signal as -70dB and increase the power level of

the unwanted signal till the measure BER value is higher than 10-4

.

5. Note down this value as Punwanted.

6. Compute the Selectivity of the receiver as per the equation (Selectivity = Punwanted -

Pwanted). Note: Pwanted is -70dB.

7. If the computed value is greater than or equal to 30dB for Adjacent channel selectivity

and greater than or equal to 40dB for the far-off selectivity then the DAB receiver passed

the selectivity test.

8. This test has to be done for both VHF and L Band.

4.1.4 Receiver Reacquisition Time

The test setup for this test is same as the selectivity test, as per the BS EN 50248, the

reacquisition time should be less than 3 seconds. It is defined as “the time of audio mute between

switching off the received ensemble and re-synchronizing to the same ensemble at an offset

frequency”.

Two VSGs are used to generate the same DAB waveform with the frequency difference between

them is half the subcarrier spacing. The subcarrier spacing depends on the transmission mode.

For Mode I, II, III and IV it is 500 Hz, 2000 Hz, 4000 Hz and 1000Hz respectively. This test

17

needs to be done separately for each mode. The DAB receiver output audio level is monitored

using the audio level analyzer or mute detection device.

Test Procedure

1. Play the same DAB waveform file in both the Vector Signal Generators.

2. Configure the frequency the two VSGs and the frequency difference should be half the

subcarrier spacing. For Mode 1 it is 500 Hz.

3. Configure the power level of both the VSGs to the same level.

4. Generate the RF signal from both the Vector Signal Generators.

5. Turn off the VSG2. Now the DAB receiver gets signal only from VSG1.

6. Turn off VSG1 and wait for 10 seconds and turn on VSG2

7. Measure the time taken for the DAB receiver to resynchronize to the DAB signal with

audio output level measurement or mute detection device.

8. Repeat the steps 5,6 and 7 for 5 times and average the measurement.

9. Repeat the measurement for all four transmission modes.

10. If the measured reacquisition time is less than 3 seconds for all the modes then the DAB

receiver passed this test.

4.2. Receiver Functionality Tests

The objective of this test procedure is to test the DAB receiver for the basic required receiver

functionalities such as Channel Search, Manual/Auto Tuning, Channel Up/Down, Audio and

Video quality measurements, EPG and to test other broadcast messages are properly handled in

the receiver.

The test setup for this test is similar to the setup shown in Figure 1.

Test Procedure

1. Configure the MaxEye DAB Signal Generation software with multiple subchannels and

service components or use the DAB ETI file that contains multiple Audio/Video channels

with other features such as EPG and other broadcast messages.

2. Generate the waveform and store it in file. Note: Generate longer duration waveform by

configuring the correct value for Number of Transmission Frames property in the

example frontpanel

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3. Configure the frequency and power level of the Vector Signal Generator.

4. Turn on the DAB receiver and perform the channel search and other tests.

5. Record the test results and the time taken for each of the tests.

6. Repeat the above tests for other receiver functionality tests. Use proper ETI file for each

test.

5. MaxEye DAB/DAB+/DMB Toolkit API

The MaxEye Digital Audio Broadcasting Signal generation toolkit allows user to completely

configure the DAB settings using LabVIEW API VIs. The diagram below shows how the API

VIs are used for configuring the signal settings. Each of the Labview programming API VI has

documentation support to the users to give more details about the functionality of the API VI and

its input and output.

The toolkit API VIs helps the users to create the custom automated test code to generate the

standard complaint signals to meet the specific test requirements.

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www.maxeyetech.com

For more information about this product and to get the evaluation copy of the latest version of

the MaxEye DAB/DAB+/TDMB Signal generation software, please contact MaxEye

Technologies

Contact Information

info@maxeyetech.com

ramesh@maxeyetech.com

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with strong expertise in providing RF test and measurement solution using NI PXI RF hardware

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