Digital Video Broadcasting-terrestrial Signals Research Articles

Novel approach for shipborne‐passive bistatic imaging with DVB‐T signals based on MIAA–RID technique

The shipborne-passive bistatic inverse synthetic aperture radar system with digital video broadcasting terrestrial (DVB-T) signals is very important in the fields of radar imaging, but it suffers from the problems of grating lobes caused by the spectral gaps when multiple DVB-T channels are applied, and the non-stationary echo signal for the complex motions of the ship. In this paper, a new algorithm based on the Missing Data Iterative Adaptive Approach (MIAA) combined with the Range Instantaneous Doppler (RID) technique is proposed to address these problems. First, the authors establish the imaging geometry and signal model. Based on these models, the range resolution and Doppler frequency are analysed. Then, the bandwidth synthesis in the frequency domain for the DVB-T signal is derived. Finally, the MIAA method is used to recover the spectral gaps of the range profile for multiple DVB-T channels, and the azimuth compression is carried out by the RID method after the translational motion compensation. Simulation results show the effectiveness of the algorithm proposed in this paper.

Pilot‐based detection for DVB‐T passive coherent location radars

This study investigates the feasibility of pilot-based detection for passive coherent location (PCL) radars exploiting digital video broadcasting-terrestrial (DVB-T) signals. The DVB-T signal is formed by two parts: a data signal and a pilot signal. The parameters of the pilot signal are known thanks to the DVB-T standards that permit the generation (at the receiver) of the pilot signal. The pilot recovery technique, based on the known DVB-T standard, is utilised in DVB-T based PCL systems to reduce the number of the reception channels by considering a locally generated pilot signal as a reference signal. Consequently, no reference channel is required, which reduces the cost and the complexity of the resulting PCL system. In this work, the authors propose a signal processing method to achieve this goal. They consider theoretical analysis, simulations and real-data results to validate the feasibility of such a system.

Analysis on the TOA Tracking With DVB-T Signals for Positioning

The digital television signal is a promising signal of opportunity for ubiquitous wireless positioning. This letter analyzes the time of arrival (TOA) tracking errors of the European standard digital video broadcasting-terrestrial (DVB-T) signals in the context of positioning. The Cramer–Rao lower bound on the unsmoothed TOA estimation is derived and an information-theoretic lower bound (ITLB) is further computed on the smoothed TOA tracking errors in delay locked loop (DLL). Theoretical analysis shows that, the increase of the bandwidth of the equivalent loop filter will lead to larger DLL tracking errors. Despite different bandwidth of the loop filters, the tracking errors derived in theory are asymptotic to ITLB with the increase of signal-noise ratio. Comparatively, the theoretical results of the DLL tracking errors are slightly larger than the ITLB, which is due to the inequality and nonlinear approximation used in the analysis. Theoretical analysis has also verified the effectiveness of the DVB-T signals to be able to achieve high accuracy in positioning.

Cognitive radio signal classification based on subspace decomposition and RBF neural networks

Spectrum sensing is one of the major challenges for commercial development of cognitive radio systems, since the detection of the presence of a primary user is a complex task that requires high reliability. This work proposes a signal classifier capable of detecting and identifying a primary user signal on a given channel of the radio spectrum. The proposed approach combines eigen-decomposition techniques and neural networks not only to decide about the presence of a primary user, but also to identify the primary user signal type, a feature that is not encountered in the current approaches proposed in literature. Besides the advantage of identifying the primary user type, the proposed method also considerably reduces the computational cost of the detection process. The proposed classification method has been applied to the development of five primary user signal Classification Modules, which includes wireless microphone, orthogonal frequency-division multiplexing and Digital Video Broadcasting-Terrestrial signals. The results show that the proposed classifier correctly detects and identifies the primary users, even under low signal to noise ratio and multipath scenarios.

Compressive sensing–based algorithm for passive bistatic ISAR with DVB-T signals

Inverse synthetic aperture radar (ISAR) images can be obtained using digital video broadcasting–terrestrial (DVB-T)–based passive radars. However, television broadcast–transmitted signals offer poor range resolution for imaging purposes, because they have a narrower bandwidth with respect to those transmitted by a dedicated ISAR system. To reach finer range resolutions, signals composed of multiple DVB-T channels are required. Problems arise, however, because DVB-T channels are typically widely separated in the frequency domain. The gaps between channels produce high grating lobes in the image domain when Fourier-based algorithms are used to form the ISAR image. In this paper, compressive sensing theory is investigated to address this problem because of its ability to reconstruct sparse signals by using incomplete measures. By solving an optimization problem under the constraint of signal sparsity, passive ISAR images can be obtained with strongly reduced grating lobes. Both simulation and experimental results are shown to demonstrate the validity of the proposed approach.

Cooperative MIMO Based Reporting System for IEEE 802.22 Standard Over Fading Channels

As cooperative spectrum sensing improves the detection probability, the multiple-input multiple-output (MIMO) system spatially transmits multiple copy of data independently to improve capacity and the IEEE 802.22 wireless regional area network standard aims to utilize the digital video broadcasting-terrestrial (DVB-T) bands opportunistically for data communication to the rural area, we consider a cooperative MIMO based reporting system where the cognitive radio users forward the DVB-T signal to the fusion center (FC) using time division multiple access. The network is operating over AWGN sensing channel and the reporting channel experiences an independent and identically distributed Rayleigh, Rician fading. We arrive an expression for average detection probability at FC for maximum ratio combining scheme. We consider the FC has the prior knowledge about the reporting channel. We analyze the system performance under various MIMO scenarios through Monte Carlo simulations.

Energy Detection of DVB-T Signals Against Noise Uncertainty

In this letter, we consider the spectrum sensing of digital video broadcasting-terrestrial (DVB-T) signals with energy detection (ED). ED delivers a superior performance among low computational complexity detectors, but it is vulnerable to noise uncertainty. By exploiting the pilot periodicity in DVB-T signals, we propose a low complexity noise power estimator which works in multipath channels, and does not require time and frequency synchronization. Simulations show that, with the noise power estimator, ED significantly outperforms the pilot correlation-based detection which is often used in DVB-T spectrum sensing.

DVB-T Signal Ambiguity Function Control for Passive Radars

The use of digital video broadcasting-terrestrial (DVB-T) signals as waveform of opportunity for passive coherent location (PCL) is addressed here. The ambiguity function (AF) of the considered waveform of opportunity has been shown to yield regularly spaced undesired peaks which might strongly limit the target detection capability of a DVB-based PCL system. A new technique for DVB-T AF control is proposed, able to overcome the limitations of previously proposed approaches in terms of achievable performance, system requirements, and computational burden. The performance analysis against simulated and real data shows that the proposed technique yields an effective removal of the undesired peaks in the AF thus making the considered waveform more attractive for PCL surveillance.

BER Performance in Digital Video Broadcasting-Terrestrial for Inner and outer Interleaving Using 64 QAM

Digital video broadcasting-terrestrial (DVB-T) was developed by the DVB Project that was first broadcast in the UK in 1997. The compressed digital audio, video and other data in Moving Picture Expert Group (MPEG) transport stream, using orthogonal frequency-division multiplexing (OFDM) modulation is transmitted by this system. In order to analyze how an MPEG transport stream at the input of a DVB-T modulator is turned into a DVB-T signal, the channel coding and modulation technique must be considered. DVB-T offers three different modulation schemes (QPSK, 16QAM, 64QAM). This paper analyzes the performance of the system for the stationary reception. The aim was to implement all the functional blocks as specified in the DVB-T specification and analyze the BER performance of the system. Thus, this paper deals with a MATLAB application being developed to simulate DVB-T system for selected QAM. This work deals with the MATLAB code to establish a system level simulation environment and use this system simulation model to evaluate the system performance hence provide the result in evaluating the performance of DVB-T with 64QAM. This system is able to measure and analyze the performance of bit error rate (BER) versus energy per bit to noise power spectral density ratio (Eb/No) for 64 QAM.

Reconciling the ETSI coverage requirements for DVB-T with the ITU-R recommendations

Digital Video Broadcasting Terrestrial (DVB-T) is a standard issued by the European Telecommunications Standards Institute (ETSI). The ETSI also issued some implementation guidelines regarding transmission aspects which include coverage requirements. For broadcasting designers, the main reference for calculating coverage is the recommendations of the International Telecommunication Union--Radiocommunication Sector (ITU-R). However, we are in trouble if we try to use the ITU-R recommendations to meet the ETSI coverage requirements because the latter specify a minimum signal level at the receiver to be guaranteed over 99 % of time whereas the ITU-R recommendations only give a calculation procedure for up to 50 % of the time. The present paper offers a method in order to adapt the ETSI coverage requirements to the ITU-R recommendations, based on a research measurement of the DVB-T signal level received in four different environments over a long period of time.

DVB-T Passive Radar Signal Processing

This paper provides a detailed overview of the Digital Video Broadcasting Terrestrial (DVB-T) signal structure and the implications for passive radar systems that use these signals as illuminators of opportunity. In particular, we analyze the ambiguity function and explain its delay and Doppler properties in terms of the underlying structure of the DVB-T signal. Of particular concern for radar range-Doppler processing are ambiguities consistent in range and Doppler with targets of interest. In this paper we adopt a mismatched filtering approach for range-Doppler processing. We also recognize that while the structure of the DVB-T signal introduces ambiguities, the structure can also be exploited to better estimate the transmitted signal and channel, as well as any mismatch between transmitter and receiver (e.g., clock offsets). This study presents a scheme for pre-processing both the reference and surveillance signals obtained by the passive radar to mitigate the effects of the ambiguities and the clutter in range-Doppler processing. The effectiveness of our proposed scheme in enhancing target detection is demonstrated using real-world data from an (Australian) 8k-mode DVB-T system. A 29 dB reduction in residual ambiguity levels over existing techniques is observed, and a 36 dB reduction over standard matched filtering; with only a 1 dB reduction in the zero-delay, zero-Doppler peak.

Feasibility analysis of utilizing the ‘8k mode’ DVB-T signal in passive radar applications

One non-cooperative illuminator recently considered for passive radar applications is the DVB-T (Digital Video Broadcasting-Terrestrial) signal. The thumbtack ambiguity function of the DVB-T signal, in addition to being stationary over time, makes such a signal a good candidate for such applications. However, certain ambiguities in its ambiguity function necessitates certain issues to be carefully considered when the DVB-T signal is to be utilized in these scenarios. Methods have been already proposed to resolve them. In this paper, after studying the origins of these ambiguities, we propose special processing schemes to reduce the complexity of the parts associated with resolving these ambiguities efficiently. Then, the DVB-T’s Cross Ambiguity Function (CAF) processing gain is carefully studied, and it is shown that its noisy nature results in a high processing gain and resolution. Finally, the detection range of the DVB-T based passive radar is examined, besides simulations, to show the practical feasibility of this signal for cases of passive coherent location.

A FPGA-based instrument for power measurement in DVB-T systems

This paper deals with the implementation of an innovative measurement instrument for power measurement in Digital Video Broadcasting Terrestrial (DVB-T) systems.In previous researches the authors have designed and tuned the measurement method. It is based on a digital signal processing section, which properly estimates the power spectrum density (PSD) of the input DVB-T signal. The peculiarities of the selected measurement algorithm have suggested the development of the instrument on a suitable FPGA platform.In this paper the hardware and the software architectures of an innovative instrument implementing the cited method are proposed. It is characterized by high transportability and exhibits metrological performance comparable with that peculiar to state-of-the-art. In particular, both the firmware solutions and optimizations, proposed to limit the resource demanding and making use of the massive parallelism offered by the FPGA architecture, are described in detail.A number of experimental tests carried out on actual DVB-T signals are also presented, whose results show the good metrological performance of the realized instrument. All measurement results concur with those provided by competitive commercial solutions.

A pilot-aided detector for spectrum sensing of Digital Video Broadcasting-Terrestrial signals in cognitive radio networks

In this paper, the main properties of digital television broadcasting signals based on the Digital Video Broadcasting—Terrestrial (DVB-T) standard are analyzed, and these properties are utilized to design a new pilot-aided detector for spectrum sensing in cognitive radio networks. The proposed detector consists of a processing unit and a combination and decision unit. In the processing unit, multiple statistics that correspond to different enhanced pilot components are computed. In the combination and decision unit, three newly proposed combination schemes are adopted to combine these statistics, and then, a final decision on the presence or absence of the DVB-T signals is made on the basis of the Neyman–Pearson criterion. The proposed pilot-aided detector exploits both the periodic continual and scattered pilots that are intrinsic in the DVB-T signals, processes the observed data timely, experiences short sensing duration, and requires no time synchronization information. Furthermore, the proposed pilot-aided detector is able to distinguish DVB-T signals from interference. Theoretical analysis and simulation results show that spectrum bands that are not currently occupied by the DVB-T systems can be detected accurately by using the proposed pilot-aided detector. Simulation results also demonstrate the significant performance gain of the proposed detector compared with the counterparts.Copyright © 2011 John Wiley & Sons, Ltd.

3PRS: a personalized popular program recommendation system for digital TV for P2P social networks

Digital TV channels require users to spend more time to choose their favorite TV programs. Electronic Program Guides (EPG) cannot be used to find popular TV programs. Hence, this paper proposes a personalized Digital Video Broadcasting -- Terrestrial(DVB-T) Digital TV program recommendation system for P2P social networks. From the DVB-T signal, we obtain EPG of TV programs. The frequency and duration of the programs that users have watched are used to extract programs that users are interested in. The information is collected and weighted by Information Retrieval (IR). The program information is then clustered by k-means. Clusters of users are also grouped by k-means to find cluster relationships. In each group, we decide the most popular program in the group according to the program weight of the channel. When a new user begins to watch the TV program, the K-Nearest Neighbor (kNN) classification method is used to determine the user's predicted cluster label. Then, our system recommends popular programs in the predicted cluster and similar clusters.

Analysis of the DVB-T Signal Variation for Indoor Portable Reception

A study of DVB-T (Digital Video Broadcasting-Terrestrial) signal variability for indoor reception environments is stated in this paper. A commercial signal was measured and analyzed in order to obtain C/N threshold values that account time and space fluctuations. In this way, results increase the accuracy of the values provided by the ETSI (European Telecommunications Standards Institute) standard and other studies that assume static propagation channels. On the other hand, the fading influence due to people walking near the reception antenna has been proved as critical for correct reception. Characterization of this effect has been made in terms of its depth and duration. The results obtained results improve DVB-T network planning and could be also relevant for other technologies sharing similar frequencies and bandwidths.

Distortion Mitigation in RF Power Amplifiers Through FPGA-Based Amplitude and Phase Predistortion

Strong requirements are currently imposed to limit the negative effects of distortion or bad synchronization between emitter and receiver in digital communication channels. Distortion is mainly caused by the output stage of the emitter's power amplifier. It can be mitigated by applying to the input signals a correction, causing them a distortion contrary to that occurring in the amplifier (i.e., a predistortion). This paper presents a new method which combines amplitude and phase predistortion for digital video broadcasting-terrestrial (DVB-T) gap fillers (intermediate reemitters) in single frequency networks. These systems impose severe limitations to the time available for processing, which prevents the application of existing predistortion techniques. The method is based on a new high-frequency model of the output stage of the emitter's power amplifier, from which the design of an efficient amplitude and phase predistorter is straightforward. An advantageous tradeoff between complexity and processing time is achieved by applying predistortion at intermediate frequency. In addition, the proposed solution is independent of the frequency of the output radio frequency signals. A predistorter has been implemented in a field-programmable gate array and applied to a real gap filler. Experimental results which show the significant improvement achieved in the quality of real DVB-T signals, as well as the low complexity and low processing delay associated to the proposed approach, are presented.

Terrestrial DVB (DVB-T): A Broadcast Technology for Stationary Portable and Mobile Use

Digital video broadcasting-terrestrial (DVB-T) is the name of the terrestrial transmission system which was developed by the DVB Project. DVB-T is in operation in many countries around the world. This paper analyzes the features of the system. It describes its capabilities with a special emphasis on mobile reception and looks at the introduction of DVB-T in Germany using the launch of DVB-T in this country as a case study. In order to analyze how an MPEG transport stream at the input of a DVB-T modulator is turned into a DVB-T signal, we consider the channel coding and modulation used. Then we look at various aspects of the system performance. The next section deals with mobile reception. Network planning issues, antenna diversity concepts for mobile receivers, and handover procedures will be considered. Finally, the introduction of DVB-T in Germany is presented as a case study. In contrast to various other countries Germany decided to offer DVB-T as a means of providing the "anywhere TV" experience. This implies that DVB-T signals can be received with mobile and portable receivers. In regions with DVB-T coverage analogue terrestrial TV services were discontinued just a few months after the launch of DVB-T.