Digital Audio Broadcasting Research Articles

DAB Eureka-147: a European vision for digital radio

Like its analogue counterpart, digital radio is one of the 'older' forms of new media. The technology of digital radio broadcasting has been under active development for at least 25 years and has produced a number of different technical solutions, the longest established of which is Eureka-147 or Digital Audio Broadcasting (DAB). This article explores DAB's distinctly European vision for the future of broadcasting. DAB is traced to its origins in 1980s European research and development policy and its affinity with traditions of European public service broadcasting. Ironically, it was DAB's failure to capitalize on its 'Europeanness' that contributed to the fragmentary political support that it later received, compromising its subsequent implementation. From a contemporary perspective DAB's original mission, while visionary, to provide enhanced, interactive information and entertainment services through audio, text and visual content, appears to have misread trends towards convergence and appears out of step with contemporary media consumption patterns.

Low-complexity FFT/IFFT IP hardware macrocells for OFDM and MIMO–OFDM CMOS transceivers

The paper presents an automated environment for fast design space exploration and automatic generation of FFT/IFFT macrocells with minimum circuit and memory complexity within the numerical accuracy budget of the target application. The effectiveness of the tool is demonstrated through FPGA and CMOS implementations (90 nm, 65 nm and 45 nm technologies) of the baseband processing in embedded OFDM transceivers. Compared with state-of-art FFT/IFFT IP cores, the proposed work provides macrocells with lower circuit complexity while keeping the same system performance (throughput, transform size and accuracy) and is the first addressing the requirements of all OFDM standards including MIMO systems: 802.11 WLAN, 802.16 WMAN, Digital Audio and Video Broadcasting in terrestrial, handheld and hybrid satellite-scenarios, Ultra Wide Band, Broadband on Power Lines, xDSL.

Scaling laws of multiple antenna group-broadcast channels

Broadcast (or point to multipoint) communication has attracted a lot of research recently. In this paper, we consider the group broadcast channel where the users' pool is divided into groups, each of which is interested in common information. Such a situation occurs for example in digital audio and video broadcast where the users are divided into various groups according to the shows they are interested in. The paper obtains upper and lower bounds for the sum rate capacity in the large number of users regime and quantifies the effect of spatial correlation on the system capacity. The paper also studies the scaling of the system capacity when the number of users and antennas grow simultaneously. It is shown that in order to achieve a constant rate per user, the number of transmit antennas should scale at least logarithmically in the number of users.

Passive bistatic radar based on target illuminations by digital audio broadcasting

A practical passive bistatic radar that is based on target illuminations by digital audio broadcasts is described. As with all such radars, direct signal interference (DSI) is identified as a major limitation, the effect being exacerbated by the multiplicity of illuminators. In addition, such multiplicity can also make the extraction of the original transmitted signal difficult. DSI is reduced by a combination of analogue and digital null formation and isolation by use of cross polarisation. Fast techniques are developed for signal extraction and digital null formation, allowing these operations to be achieved in real time. Both the hardware and algorithms of the system are described and representative radar observations are included to show the systems effectiveness.

A T-DAB Field Trial Using a Low-Mast Infrastructure

A novel low-mast low-power terrestrial digital audio broadcasting (T-DAB) single frequency network topology is described and evaluated in this paper. For this purpose, a pilot network (band III and L-band) was constructed in Amsterdam, the Netherlands. The performance of the band III pilot network (channel 12B) is compared with the existing traditional high-power high-mast T-DAB network (channel 12C) of the public service broadcaster. An important goal is to investigate whether the pilot network can co-exist with an existing traditional T-DAB network. The field trial shows that a gap filler can effectively neutralize the adjacent channel interference of the pilot network on the existing T-DAB network. Moreover, the L-band pilot network is compared with both band III networks by assessing the indoor coverage of every network. For estimation of the indoor coverage, 34 objects were investigated. Both the indoor penetration loss for band III and L-band was determined for each object. Indoor coverage in a region is reached if 95% of the buildings or more have indoor coverage. Using this definition, the loss for band III is 21.6 dB and for L-band 24.6 dB. As a result we consider the indoor penetration loss values reported in literature as too optimistic. Also other parameters of the pilot network were measured, such as the frequency re-use distance.

A multichannel monitoring digital radio DAB utilizing a memory function and verbal queries to search for audio and data content

The aim of this paper is to present the concept for the development of an entirely speech-based user interface for a digital radio in combination with the possibility to specifically search for audio and data content. On the basis of a Digital Audio Broadcasting DAB device the embedded system utilizes a multichannel receiver with the possibility of simultaneously monitoring a variety of information sources with the purpose to generate spoken replies to verbal user requests. Furthermore, the system embraces an audio repository storing speech-based content elements to diminish the volatile property of broadcast content and to enable a memory function.

A 10 b 25 MS/s 4.8 mW 0.13 µm CMOS ADC with switched‐bias power‐reduction techniques

AbstractThis paper proposes a 10 b 25 MS/s 4.8 mW 0.13 µm CMOS analog‐to‐digital converter (ADC) for high‐performance portable wireless communication systems, such as digital video broadcasting, digital audio broadcasting, and digital multimedia broadcasting (DMB) systems, simultaneously requiring a low‐voltage, low‐power, and small chip area. A two‐stage pipeline architecture optimizes the overall chip area and power dissipation of the proposed ADC at the target resolution and sampling rate, while switched‐bias power‐reduction techniques reduce the power consumption of the power‐hungry analog amplifiers. Low‐noise reference currents and voltages are implemented on chip with optional off‐chip voltage references for low‐power system‐on‐a‐chip applications. An optional down‐sampling clock signal selects a sampling rate of 25 or 10 MS/s depending on applications in order to further reduce the power dissipation. The prototype ADC fabricated in a 0.13 µm 1P8M CMOS technology demonstrates a measured peak differential non‐linearity and integral non‐linearity within 0.42 LSB and 0.91 LSB and shows a maximum signal‐to‐noise‐and‐distortion ratio and spurious‐free dynamic range of 56 and 65 dB at all sampling frequencies up to 25 MHz, respectively. The ADC with an active die area of 0.8 mm2 consumes 4.8 and 2.4 mW at 25 and 10 MS/s, respectively, with a 1.2 V supply. Copyright © 2008 John Wiley & Sons, Ltd.

RF Performance of T-DAB Receivers

In every wireless system, the weakest link determines the performance of the network. In this paper the Radio Frequency (RF) performance of both band III and L-band Terrestrial Digital Audio Broadcasting (T-DAB) consumer receivers are discussed. The receivers have been tested based on the EN 50248 standard. The test results show that the average consumer receiver for band III meets the requirements set by EN 50248, except for the non-adjacent interferer experiments. In this experiment, the average consumer receiver performs up to 10 dB worse than required. In addition, the experiments reveal that there is a large difference in performance between consumer receivers. Besides band III, also L-band consumer receivers have been evaluated. The results of the L-band experiments show that the consumer receivers are not capable of decoding a DAB signal with a COST207 rural area channel model in case of T-DAB mode IV. Network operators should for this reason use mode II for the L-band and should expect a larger influence of non-adjacent interference on receiver performance in band III than anticipated based on EN 50248.

Field Tests of Digital Audio Broadcasting in the FM Band Based on Continuous Phase Modulation

We propose a new broadcasting scheme for the transmission of digital audio signals simultaneously with existing analog frequency modulation radio (88-108 MHz) in adjacent channels, denoted as in-band-adjacent channel system (IBAC) . This broadcasting scheme enables the transmission of digital audio data in CD quality with a data rate of up to 156 kb/s within an FM 200 kHz channel. The digital transmission is based on continuous phase modulation (CPM) and a proper reduced-state sequence estimator. CPM is the digital equivalent of the analog FM and has a constant envelope, too. This is a great advantage, because on the one hand existing nonlinear amplifiers can be reused to achieve good efficiency and low out-of-band radiation, on the other hand it enables the broadcasting companies to reuse the existing infrastructure (amplifiers, antennas, frequency bands) which reduces the investment costs and improves the chances for an introduction of CPM as a new broadcasting standard. With the proposed method, the power level and the symbol rate of the transmitter signal is determined in a manner that the interference the CPM signal poses for the analog FM signal in adjacent channels remains below a level according to the radio frequency emission mask defined by international rules. Due to the multipath propagation of the transmitted signal, the transmission behavior of typical radio channels is characterized by high dispersion of up to 85 . For the parameterization of this demonstrator, the channel memory amounts 14 bits. Due to the implementation of the hardware, the symbol duration is different in this case from the one in . Since Viterbi detection is not feasible due to the number of channel states, detection is performed by a reduced-state sequence estimator that is able to eliminate the complete channel interferences by decision feedback . We will describe in this paper the underlying algorithms of synchronization and channel estimation, since they are important components of a real receiver. To underline the suitability of the CPM based broadcasting scheme, we have conducted field tests in the city area of Hanover with a real broadcasting evaluation system based on the proposed CPM broadcasting scheme with support of the northern German broadcast service (NDR) in Hanover with encouraging results.

SPOCS: Application Specific Signal Processor for OFDM Communication Systems

This paper presents an Application-Specific Signal Processor (ASSP) for Orthogonal Frequency Division Multiplexing (OFDM) Communication Systems, called SPOCS. The instruction set and its architecture are specially designed for OFDM systems, such as Fast Fourier Transform (FFT), scrambling/descrambling, puncturing, convolutional encoding, interleaving/deinterleaving, etc. SPOCS employs the optimized Data Processing Unit (DPU) to support the proposed instructions and the FFT Address Generation Unit (FAGU) to automatically calculate input/output data addresses. In addition, the proposed Bit Manipulation Unit (BMU) supports efficient bit manipulation operations. SPOCS has been synthesized using the SEC 0.18 μm standard cell library and has a much smaller area than commercial DSP chips. SPOCS can reduce the number of clock cycles over 8%~53% for FFT and about 48%~84% for scrambling, convolutional encoding and interleaving compared with existing DSP chips. SPOCS can support various OFDM communication standards, such as Wireless Local Area Network (WLAN), Digital Audio Broadcasting (DAB), Digital Video Broadcasting-Terrestrial (DVB-T), etc.

The Future of Radio is Still Digital—But Which One? Expert Perspectives and Future Scenarios for Radio Media in 2015

The future of radio is now much less obvious and clear than it appeared 10 years ago. Instead of a transition from analog to digital audio broadcasting (DAB), there is a selection of alternative technological options for digital audio delivery. This article studies how 43 people in key positions related to the radio industry in four European countries and Canada view the future of radio and which delivery technologies they consider will be most successful. In addition, it analyzes the motives and reasons why certain technologies are seen as more promising. Finally, it presents different future scenarios for radio media.

MPEG-4 high-efficiency AAC coding [Standards in a Nutshell

The name MPEG-4 high-efficiency AAC (HE-AAC) refers to a family of recent audio coders that was developed by the International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) Moving Picture Experts Group (MPEG) by subsequent extension of the established Advanced Audio Coding (AAC) architecture. These algorithmic extensions facilitate a significant increase in coding efficiency relative to previous standards and other known systems. Thus, they provide a representation for generic audio/music signals that offers high audio quality also to applications limited in transmission bandwidth or storage capacity, such as digital audio broadcasting and wireless music access for cellular phones. This article presents a compact overview of the evolution, technology, and performance of the MPEG-4 HE-AAC coding family.

DAB: the future of radio? The development of digital radio in four European countries

In common with most media and consumer technologies, radio is migrating from analogue to digital operation. Europe was the first region of the world to develop a digital replacement for traditional analogue broadcast radio. The Digital Audio Broadcasting (DAB) project began in 1987 and the first domestic DAB broadcasts began in 1995. However, DAB has made less progress than originally anticipated: some countries are at a relatively advanced level of development while others have not begun significant DAB services. This paper examines the development of the DAB service in four European countries, illustrating the variability in modes of development. The different digital policies adopted by each country is a key factor in these developments and we show how the existing state of analogue radio and the limitations of the technical system have shaped these policies.

The Performance Analysis of Backward Compatible Modulation With Higher Spectrum Efficiency for DAB Eureka 147

Based on the standard of digital audio broadcasting (DAB) Eureka 147 system to improve structures of transmitter/receiver, this paper proposes a physical layer transmission technique capable of boosting the spectrum efficiency up to two times of that of the DAB-Eureka 147 system while the backwards compatibility is guaranteed. The proposed transmission technique comprises the development of both the modulation and demodulation schemes. In the developed modulation scheme, differential 16-level amplitude/ phase shift keying (D16 APSK) is adopted to replace the differential quadrature-phase-shift-keying (DQPSK) used in the DAB Eureka 147 system. In the developed demodulation scheme, on the other hand, a detector for two-level differential amplitude-shift-keying (DASK) signal is proposed which can be implemented with rather low hardware costs. The performance is presented by the Simulink platform in multipath fading channel model.

Bistatic Radar Based on DAB Ifluminators: The Evolution of a Practical System

Digital Audio Broadcasting (DAB) has massive potential for the development of passive bistatic radar. A project to build DAB based radar is described, together with its advantages and disadvantages. Several serious obstacles need to be overcome in order to make the system a reality. Most importantly, these include the removal of direct signal interference and the extraction of the illuminating signal in a form suitable for detections. Progress toward the solution of these problems will be described. In addition, some real aircraft detections are included to prove the viability of a practical system.

A Statistical Model to Estimate an Upper Bound on the Probability of Failure of a System Installed on an Irradiated Vehicle

This paper presents a risk assessment model suitable for predicting an upper bound on the probability of failure of an electronic system installed inside a vehicle that is irradiated externally or internally. Only limited information on the immunity of the device and associated cabling is required. As an example, the model is used to demonstrate an upper bound on the probability of failure of a system due to irradiation from digital audio broadcast transmitters in the U.K. The failure probability is found to be highly dependent on the clearance distance above the vehicle chassis of wire looms attached to the system, and to the accuracy with which the electric field is measured during an immunity test for the system/cable combination. The failure probability predicted by the risk assessment model is consistent with common observations of a log-normal distribution in the terminating power of receiving cables inside an irradiated vehicle or reverberation chamber.

Exposure of the general public to digital broadcast transmitters compared to analogue ones

The terrestrial digital video and audio broadcast are supposed to replace the existing analogue broadcast systems. To determine possible changes of this switchover on the public exposure situation to radio frequency electromagnetic fields, extensive measurements at more than 300 identical points were performed 'before' and accordingly 'after' the switchover. At the point with the highest sum-exposure, only 0.3% of the ICNIRP reference levels for general public exposure (power flux density) was reached. The statistical analysis of both measurement campaigns ('before-after') shows an increase in mean exposure in the centre of the DVB-T starting areas around Nuremberg and Munich, which is mainly based on the increase in the radiated power at the transmitter stations. After developing a simple calculation program based on the ITU-RP.1546, the measured exposure values were compared to calculations. Optimising the results leads to mean deviations of +/-3 dB at about 80% of all points.

An Efficient FFT Processor for DAB Receiver Using Circuit-Sharing Pipeline Design

With the upcoming fourth generation wireless systems and convergence of multiple radio standards into a single terminal, building blocks are needed that can be configured for computing various algorithms used in different standards. Given these trends and requirements, in our previous paper we successfully proposed a circuit-sharing design for the DAB receiver to integrate the FFT (fast Fourier transform) and IMDCT (inverse modified discrete cosine transform) operations into the same functional circuit. The proposed technique reduces hardware overhead, enhances circuit efficiency and significantly reduces the cost of DAB receivers. To further improve the efficiency of our previous work, this investigation proposes another alternative design named the circuit-sharing pipeline design (CSPD) using a single processor with a pipeline scheme to combine two functions, FFT and IMDCT, into the same circuit. The proposed method reduces the required chip area and cost of DAB receivers. Analyzing the existing relationship among IMDCT, DCT (discrete cosine transform) and FFT, the IMDCT function can be replaced using a FFT function. Therefore, it is not necessary to design an extra circuit for IMDCT. The arithmetic unit in the FFT processor can be significantly reduced due to employing the pipeline scheme. Consequently, the circuit redundancies in the IMDCT and FFT functions can be easily eliminated to allow exploitation of the decreased chip area. Results of this study demonstrate that the proposed design can provide advantages such as low gate count and small memory size in the DAB (digital audio broadcasting) receiver.

Towards a configurable SoC MPEG-4 advanced simple profile decoder

The evaluation of various architectural designs to allow low bandwidth digital video decoding and reception over the digital audio broadcasting network, and the problem of how to find and implement an optimal HW/SW partition on a Programmable Logic Device with an embedded ARM9 processor are focused. Profiling and design space exploration techniques are applied to the advanced simple profile of an MPEG-4 decoder, for which an innovative SystemC-based system-level design tool, called CASSE, has been used. Simulations results showed that a throughput of 15 QCIF frames per second can be achieved with a low area and low power implementation. Details of this implementation and where the results differ from simulation are presented.

An Area-Efficient Design of Variable-Length Fast Fourier Transform Processor

Fast Fourier transform (FFT) plays an important role in the orthogonal frequency division multiplexing (OFDM) communication systems. In this paper, we propose an area-efficient design of variable-length FFT processor which can perform various FFT lengths of 512/1,024/2,048/4,096/8,192 points used in OFDM-based communication systems, such as digital audio broadcasting (DAB), digital video broadcasting-terrestrial (DVB-T) and digital video broadcasting-handheld (DVB-H). To reduce computational complexity and chip area, we develop a new variable-length FFT architecture by devising a mixed-radix algorithm that consist of radix-2, radix-22 and radix-2/4/8 algorithms and optimizing the realization by substructure sharing. Based on this architecture, an area-efficient design of variable-length FFT processor is presented. By synthesized using the UMC 0.18 μm process, the area of the processor is 2.9 mm2 and the 8,192-point FFT can be performed correctly up to 50 MHz with power consumption 823 mW under a 1.8 V supply voltage.