Digital Audio Broadcasting Receiver Testing Solutions

Introduction

Digital Audio Broadcasting (DAB) is the most widely adopted technology for digital radio broadcast­ing. DAB-based standards, including the recently developed DAB+ and DMB, support video and data services in addition to audio service.

The British standard, BS EN 50248 “Characteristics of DAB Receivers”, describes DAB receiver characteristics for commercial equipment intended for terrestrial and cable reception in band III and L- band and for satellite reception in L-band.

This document discusses the measurement configurations and procedures for DAB receiver RF performance test using Keysight Technologies, Inc. instruments, according to BS EN 50248.

DAB Receiver Test Demonstrations

Overview of requirements for DAB receiver test

BS EN 50248 includes both basic and functional performance requirements for DAB receivers, as well as the minimum performance levels and measuring methods. The RF performance tests stipulated in the standard are as follows.

Sensitivity in a Gaussian channel

Maximum input power in a Gaussian channel

Selectivity, including two parts:Adjacent channel selectivity

Rejection of unwanted signals (far-off selectivity)

Performance in a Rayleigh channelSensitivity

Acquisition time after synchronization loss

All the measurements listed above need to be performed in both the VHF band and the L-Band as below:

VHF Band III: 174 MHz ~ 240 MHz

L-Band: 1452 MHz ~ 1492 MHz

The BER result of 10-4 is used as the criteria in all tests. The BER should be mea­sured at the convolutional decoder output of the receiver and performed in the MSC (Main Service Channel) using an EEP (equal error protection) sub-channel with code rate ½. Note that while some receivers can provide BER results, if they cannot, an extra BER meter is required to measure the BER results. Any known digital pattern with a length of more than 1 symbol can be used as the test sequence – for example, all zero sequence.

Sensitivity and maximum input power in a Gaussian channel

Sensitivity and maximum input power are the minimum and maximum input signal levels of the DAB receiver at which the BER result meets the criteria as stipulated in BS EN 50248.

For the sensitivity test, the minimum requirement in EN 50248 is –81 dBm for both VHF band and L-band. If the measured power is lower than this value, it means the receiver passes the sensitivity test.