Digital Video Signals Research Articles

ТЕРАГЕРЦОВІ ТЕХНОЛОГІЇ В ТЕЛЕКОМУНІКАЦІЙНИХ СИСТЕМАХ. ЧАСТИНА 2. ДОСЛІДЖЕННЯ ТА МОДЕЛЮВАННЯ ПЕРЕДАВАННЯ ТЕЛЕВІЗІЙНИХ СИГНАЛІВ СТАНДАРТУ DVB-C І ІМПУЛЬСНОГО НАДШИРОКОСМУГОВОГО СИГНАЛУ РАДІОЛІНІЄЮ ТЕРАГЕРЦОВОГО ДІАПАЗОНУ

The laboratory testbed of a digital simplex radio-relay system of the terahertz range has been studied for the first time in practical terms. It consists of the receiver and transmitter parts of 130÷134 GHz frequency range and a digital modem with a channel data transmission of up to 1200 Mbps for a communication point-to-point distance under normal conditions within 1 km. It is shown that the proposed telecommunication system, which implements the concept of the creation of software-defined radio systems based on Wi-Fi technology, can be highly productive in the next generation mobile communication networks providing the appropriate transmission speeds, reliability, and security. It is studied the parameters of multichannel digital TV signal DVB-C standard when it is transmitted through the testbed of the transmitter and receiver parts of 130 GHz band. The results of the research showed that the application of lower part of terahertz frequency band (130 GHz) with a bandwidth of 24 MHz allows the transmission of three DVB-C television broadcasting channels with a total transport speed of 125 Mbit/s with a high subjective quality of TV programs. The results of the simulation of impulse ultrawideband (IR-UWB) signal transmission by the wireless link of terahertz band are presented. The results of researches of changes of IR-UWB Gaussian monocycle in the transmitter part and its reception by the receiver part of 130.4÷131.5 GHz terahertz band are presented for the first time. On the basis of the results of the research, the requirements for parameters of terahertz wireless link are formulated to ensure acceptable quality of ultrawideband impulse signals receiving. Development of the transmitter and receiver parts of radio relay system of the terahertz range has no direct current analogs in Ukraine. It can provide a significant breakthrough in the development of the telecommunications industry. The obtained research results will also contribute to the development of telecommunications-related industries, in particular: radio astronomy, inter-satellite communication, radar systems, medicine, etc.

Passive bistatic radar using digital video broadcasting-terrestrial receivers as general-purpose software-defined radio receivers.

We investigate the use of low-cost digital video broadcasting-terrestrial (DVB-T) receivers as general-purpose software-defined radio (SDR) receivers for passive bistatic radar (PBR) applications. Two DVB-T receivers are synchronized using a common clock to perform coherent measurements. By exploiting the direct-path signal in the surveillance channel, we use the cross-correlation process to estimate the time offset between the data streams of reference and surveillance channels caused by the universal serial bus communication. We demonstrate the detection of static and moving targets as well as short-range targets, including a landing airplane at 8 km, multiple ships with different velocities, and vehicles within 20 m from the receiver acquiring at a 2 MHz bandwidth, by using Japan's Integrated Services Digital Broadcasting Terrestrial digital TeleVision (TV) signal broadcast. We also propose to improve the range resolution of the designed PBR system by combining multiple SDR receivers tuned to different carrier frequencies. The designed system and proposed method can be used for various applications, such as airplane navigation, harbor protection, and traffic density monitoring.

Epitaxial Growth of InGaN Multiple-Quantum-Well LEDs With Improved Characteristics and Their Application in Underwater Optical Wireless Communications

InGaN light-emitting diodes (LEDs) grown with a thin GaN barrier and a gradually reduced well width in the multiple-quantum-well (MQW) regions close to n-GaN are proposed for use in underwater optical wireless communications. Experimentally, LED epiwafers grown by metal–organic vapor phase epitaxy were found to have comparable crystalline quality despite using a different epistructure design from InGaN MQWs. The modified MQWs facilitated hole transport to the deep quantum wells while preventing energetic electrons from accumulating at the topmost quantum wells close to p-GaN, thus improving the current-light output performance at high currents. In addition, relatively strong carrier localization in the proposed LEDs indicates more injected carriers within the modified MQWs can participate in radiative recombinations to contribute to light output. On the other hand, the available bandwidth of a line-of-sight LED-based optical link passing through a 100-cm-long water tank was found to be around 148.7 MHz using the proposed LED, which is $1.3\times $ higher than that obtained using normal LED. This type of optical link produces data transmission at rates in tap water exceeding 300 Mbit/s and enables real-time transmission of digital TV signals.

Grassmann Manifold-Based Spectrum Sensing for TV White Spaces

In this paper, a new method of sensing primary user’s signal for cognitive radios in Grassmann manifold is proposed. The Grassmann covariance matrix (GCM) is formed with the help of covariance matrix of the transmitted and the received symbols. By using GCM, a new test statistic is defined, which is the modification of Binet–Cauchy metric. On the basis of this new test statistic, primary user’s signal is detected. We also show that the new test statistic is a valid detector since it follows the concentration phenomena. We derive the distribution of new test statistic under null hypothesis and alternative hypothesis. Lower bound for the probability of detection of signal is also derived using separating function and distribution of new test statistic. Simulations using the real-world measurements of digital television (DTV) signal show performance gain of the proposed method in terms of signal detection over existing methods and their agreement with the derived distribution. Additionally, we extend the proposed method for the cooperative spectrum sensing and derive the distribution under both hypotheses. Experimental verification on the software defined radio is also performed and it is found that the proposed method fulfills the requirement of maximum protection of the DTV signal.

News media and crime perceptions: Evidence from a natural experiment

In democracies, voters rely on media outlets to learn about politically salient issues. This raises an important question: how strongly can media affect public perceptions? This paper uses a natural experiment – the staggered introduction of the Digital TV signal in Italy – to measure the effect of media persuasion on the perceptions individuals hold. We focus on crime perceptions and, combining channel-specific viewership and content data, we show that the reduced exposure to channels characterized by high levels of crime reporting decreases individual concerns about crime. The effect is driven by individuals aged 50 and over, who turn out to be more exposed to television while using other sources of information less frequently. Finally, we provide evidence about the effect of the digital introduction on public policies closely related to crime perceptions and on voting behaviour.

LogDet Covariance Based Spectrum Sensing Under Colored Noise

Cognitive radio is proposed for efficient utilization of radio spectrum using dynamic spectrum allocation. Most of the spectrum sensing algorithms for cognitive radio are based on some operations on eigenvalue of the covariance matrix of received symbols. However, the performance of existing algorithms degrade in the presence of colored noise due to swelling effect of the covariance matrix. To circumvent this limitation, we propose to use LogDet of covariance matrix of the received samples for spectrum sensing in cognitive radio. The proposed algorithms work extremely well at low signal-to-noise ratio in the presence of both white and colored noise. We also derive the detection threshold of the proposed algorithms. Simulation results show robustness of the proposed algorithms over existing algorithms on the captured digital television signal.

Polarisation experimental research of passive radar based on digital television signal

The Letter aims to investigate the polarisation diversity for passive radar system. Digital television signal is used as the illuminator of opportunity in this experiment. Dual-polarised Yagi-Uda antennas have been independently designed as surveillance array antennas, which can receive horizontal (H) and vertical (V) polarisation simultaneously. The experimental results showed that the detection performance after polarisation processing depends on the difference between target polarisation state and interference polarisation state. The target detection performance will be improved if the technology of polarisation diversity is used.

In brief

PAGE 395 A solution to avoid relay attacks on keyless entry systems in vehicles is proposed in work from Korea. In conventional systems, the proximity of the key to the vehicle is approximated using received signal strength. The proposed approach applies an additional layer of security using a channel correlation-based proximity authentication scheme to prevent relay attacks. PAGE 376 Researchers in the USA report the use of a digital filter with adaptive coefficients to correct current sensing and temperature variation in DC/DC switch mode power supplies. Tighter output voltage regulation is achieved with this filter and current sensing can be applied to systems without adaptive voltage positioning. The filter is suitable for computing, telecom, and storage applications. A channel correlation-based proximity authentication scheme for keyless entry systems for vehicles. PAGE 385 Digital television signals in urban environments are used to improve passive radar target detection performance in work from China. This work combines traditional polarisation theories with passive radar detection to reduce interference within built up urban environments using a dual-polarisation antenna array. Correct current sensing with a digital filter with adaptive coefficients for DC/DC switch mode power supplies. PAGE 336 Researchers in Japan make a combined wireless local area network system and smart antenna to suppress interference in busy locations, such as shopping malls and stadiums. The device has eight internal antennas that are dynamically selected by high-speed switching to maintain network service. A large improvement in interface suppression with this device is demonstrated in comparison with centralised antennas. Passive target detection in urban areas is improved by taking advantage of polarisation diversity in digital television signals. PAGE 359 Electromagnetic reflectivity from twill-weave carbon fibre reinforced polymers (CFRP) is measured in work from Austria. Different fibre patterns of the CFRP were investigated, including unidirectional, shredded and twill-weave fibres. Twill-weave fibres showed a sharp angular dependency in reflectivity in response to millimetre waves at 60 GHz. The fibres are manufacturing materials for vehicles and are targets for millimetre wave radar. Integration of eight internal antennas into a wireless local area network system to suppress interference in busy locations. The electromagnetic reflectivities of different patterns of carbon fibre reinforced polymers are measured.

Assessment of the Dominant Path Model and Field Measurements for NLOS DTV Signal Propagation

In Brazil, one of the most important telecommunications systems is broadcast television. Such relevance demands an extensive analysis to be performed chasing technical excellence in order to offer a better digital transmission to the user. Therefore, it is mandatory to evaluate the quality and strength of the Digital TV signal, through studies of coverage predictions models, allowing stations to be projected in a way that their respective signals are harmoniously distributed. The purpose of this study is to appraise measurements of digital television signal obtained in the field and to compare them with numerical results from the simulation of the Dominant Path Model. The outcomes indicate possible blocking zones and a low accumulated probability index above the reception threshold, as well as characterise the gain level of the receiving antenna, which would prevent signal blocking.

The Design and Implementation of Digital TV Signal Receiving System Based on National Standard DTMB

The design and development of digital TV signal ground receiving system based on the national standard of DTMB, the hardware of the system is composed of main decoding chip Hi2019E, channel demodulation and channel decoding chip Hi330, high-frequency chip TD1600, Flash and SDAM. Operating system uses UC/OS Ⅱ the real-time operating system, and designs the application layer and driver layer, realizes the channel to lock. The system is used at the county level radio and television system, the receiving threshold in the 20dB μ V digital TV signal can be reliably received, meet the DTMB standard requirements.

Experimental Research of Multistatic Passive Radar With a Single Antenna for Drone Detection

Digital television signals are attractive illuminations of opportunity for the passive radars in the field of low altitude and slow speed target detection. The digital television standard permits reconstruction of a reference signal using the received signal in surveillance channel, which enables a single-antenna digital television based passive radar (SDPR) processing. This paper investigates the practical feasibility of a multistatic SDPR (MSDPR) for the drone detection. First, the detection range of the SDPR is analyzed in terms of signal processing procedures involving multipath energy, extracted reference signal purity, and receiving antenna. Second, according to the characteristics of the SDPR, the reference signal extraction is analyzed. In addition, considering that the SDPR cannot locate and track the detected target, a novel MSDPR processing method is proposed. The core idea of this method is to use the optimal reference signal extracted from the receiving station with the least interference as the shared reference signal in MSDPR, which can greatly improve the system detection capability. Finally, the small drone detection experiments using the MSDPR are presented. The theoretical considerations are demonstrated using the experimental data.

News Media and Crime Perceptions: Evidence from a Natural Experiment

In democracies voters rely on media outlets to learn about politically salient issues. This raises an important question: how strongly can media affect public perceptions? This paper uses a natural experiment – the staggered introduction of the Digital TV signal in Italy – to measure the effect of media persuasion on the perceptions individuals hold. We focus on crime perceptions and, combining channel-specific viewership and content data, we show that the reduced exposure to channels characterized by high levels of crime reporting decreases individual concerns about crime. The effect is driven by individuals aged 50 and over, who turn out to be more exposed to television while using other sources of information less frequently. Finally, we provide some evidence about the effect of the digital introduction on public policies closely related to crime perceptions and on voting behavior.

Digital TV signal reception and amplification system

Digital TV signal reception and amplification system

Robot-Embodied Neuronal Networks as an Interactive Model of Learning.

Background and Objective:The reductionist approach of neuronal cell culture has been useful for analyses of synaptic signaling. Murine cortical neurons in culture spontaneously form an ex vivo network capable of transmitting complex signals, and have been useful for analyses of several fundamental aspects of neuronal development hitherto difficult to clarify in situ. However, these networks lack the ability to receive and respond to sensory input from the environment as do neurons in vivo. Establishment of these networks in culture chambers containing multi-electrode arrays allows recording of synaptic activity as well as stimulation.Method:This article describes the embodiment of ex vivo neuronal networks neurons in a closed-loop cybernetic system, consisting of digitized video signals as sensory input and a robot arm as motor output.Results:In this system, the neuronal network essentially functions as a simple central nervous system. This embodied network displays the ability to track a target in a naturalistic environment. These findings underscore that ex vivo neuronal networks can respond to sensory input and direct motor output.Conclusion:These analyses may contribute to optimization of neuronal-computer interfaces for perceptive and locomotive prosthetic applications. Ex vivo networks display critical alterations in signal patterns following treatment with subcytotoxic concentrations of amyloid-beta. Future studies including comparison of tracking accuracy of embodied networks prepared from mice harboring key mutations with those from normal mice, accompanied with exposure to Abeta and/or other neurotoxins, may provide a useful model system for monitoring subtle impairment of neuronal function as well as normal and abnormal development.

Joint Wireless Positioning and Emitter Identification in DVB-T Single Frequency Networks

Digital television (DTV) signal has been recognized as a promising signal for navigation and positioning. However, due to the single frequency network (SFN) transmission within the European standard digital video broadcasting terrestrial (DVB-T) system, emitter confusion problem occurs in navigation and positioning, resulting in that a receiver is unable to know from which emitter a received signal comes. In this paper, we consider the wireless positioning with emitter confusion problem in DVB-T SFN networks. A joint wireless positioning and emitter identification algorithm is proposed, which is based on the expectation maximization (EM) method. The proposed algorithm is tested in a scenario, where signals are received from three to five emitters. Simulation results show that, relying on more than three emitters used in the tests for 2-D positioning, the EM-assisted positioning algorithm is feasible to achieve accurate positioning results in the existence of the emitter confusion problem. Our studies show that the performance achieved by the proposed algorithm approaches the Cramer-Rao bound. Furthermore, the proposed algorithm is effective to identify the DTV emitters, and the positioning performance is robust to the emitter identification error. Additionally, our methodology is general, and can be employed for time of arrival-based positioning in any SFNs.

Evaluation of Direct Signal Suppression for Passive Radar

Passive radar (PR) systems must be able to detect the presence of a target signal many orders of magnitude weaker than the direct signal interference (DSI). Due to the continuous nature of most PR signals, this interference, rather than thermal noise, determines the sensitivity of the system. Suppression of DSI and clutter prior to range-Doppler processing is crucial for maximizing the effective dynamic range, to increase detection range and improve overall system performance. A number of time-domain adaptive filtering techniques have been proposed to mitigate the effects of DSI, with varying levels of success. As such, an investigation of the primary factors affecting suppression performance is presented, using Advanced Television Systems Committee digital television (DTV) waveforms as an example, through simulation and extensive experimental trials. A number of spectral and spatially diverse DTV signals are considered to analyze suppression performance under a wide range of realistic scenarios. In particular, the fast block least mean squares filter is shown to provide good suppression performance with low computational requirements. Results of this analysis can be used to predict PR performance and stability. Practical metrics, such as suppression runtime and ease of implementation, also serve to counsel selection of DSI mitigation algorithms for experimental systems.

Serial digital interface video signal jitter generator and its calibration method

Jitter is an important factor for serial digital interface video signal (SDI signal) analysis. In this paper, we present the simulated SDI signal generator with certain amount of jitter using a sinusoidal frequency modulation (FM) signal, and propose a calibration method for the jitter value based on modulation index and relative power of sinusoidal FM signal. An experimental system is set up to generate and calibrate SDI signal with specific jitters. High-definition (HD) SDI signal with bit rate of 1.485Gbit/s is employed to describe the calibration procedure and analyze the uncertainty of measurement.

The Influences of Meteorological Parameters on Digital Terrestrial Television (DTT) Signal in the Tropics

The Influences of Meteorological Parameters on Digital Terrestrial Television (DTT) Signal in the Tropics

Assessment of digital television signal processing for correction of interference distortions in single-frequency DVB networks

This research studies in which way the interference that occurs in Single-Frequency Networks for Digital Television broadcasting affects the reception quality in the overlapping service zones of transmitters. The article contains qualitative and quantitative evaluation of the effectiveness of the interference distortion compensation in the receiver’s demodulator. The results were obtained using CADs VSS Applied Wave Research and ADS Agilent Technologies and allow us to evaluate a limiting value of the signal-to-echo-signal ratio for a given signal-to-noise ratio that provides the network operability. The DVB network operability in the presence of transmitter clocking depends on the stability margin, which is defined by the permissible value of a bit error rate (BER) within a threshold. From the obtained results it follows that the interference-impact threshold corresponds to the BER equal to 2 × 10-4. For below-threshold BER values, the reception becomes almost error-free due to the use of a Reed-Solomon decoder. Codec replacement in the second-generation DVB networks resulted in a significantly decreased BER threshold value to 10-2 – 10-3, which allowed the data transfer rate to be increased while keeping the stability margin in terms of the bit error rate. The developed method for studying the performance of digital broadcasting networks and systems allows causes behind the increase of BER to be identified in practice based on spectra and signal constellations diagrams, also enabling the comparison of various algorithms for the assessment of data channel performance and digital television signal processing in terms of the effective suppression of interference distortions.

Prevention of Emulation Attack in Cognitive Radio Networks Using Integrated Authentication

Security is the prominent problem in emerging cognitive radio. Protecting the chief user’s and sub-ordinate user’s right to use the spectrum results in the correct cognitive radio operation. The major user emulation attack is a physical layer attack which disrupts the secondary user’s operation. An Advanced Encryption Standard scheme is used in this work that aims to defeat the chief User Emulation Attack by the correct detection of the chief user. The reference signal is encrypted and transmitted along with the Digital TV signal. Using a shared secret the receiver regenerates the reference and the cross association and the auto correlation are calculated which helps in the accurate detection of the chief user as well as the malicious user. The simulations were carried out and the results show that the detection scheme results in zero misdetection and also false alarm which is below a set threshold.