DTV Signal Research Articles

A fuzzing‐based test‐creation approach for evaluating digital TV receivers via transport streams

AbstractDigital TV (DTV) receivers are usually submitted to testing systems for conformity and robustness assessment, and their approval implies correct operation under a given DTV specification protocol. However, many broadcasters inadvertently misconfigure their devices and transmit the wrong information concerning data structures and protocol format. Since most receivers were not designed to operate under such conditions, malfunction and incorrect behaviour may be noticed, often recognized as field problems, thus compromising a given system's operation. Moreover, the way those problems are usually introduced in DTV signals presents some randomness, but with known restrictions given by the underlying transport protocols used in DTV systems, which resembles fuzzing techniques. Indeed, everything may happen since any deviation can incur problems, depending on each specific implementation. This error scenario is addressed here, and a novel receiver robustness evaluation methodology based on non‐compliance tests using grammar‐based guided fuzzing is proposed. In particular, devices are submitted to unforeseen conditions and incorrect configuration. They are created with guided fuzzing based on real problems, protocol structure, and system architecture to provide resources for handling them, thus ensuring correct operation. Experiments using such a fuzzing scheme have shown its efficacy and provided opportunities to improve robustness regarding commercial DTV platforms.

Broadband printed dipole antenna with integrated balun and tuning element for DTV application

This paper presents the broadband printed dipole antenna design with an integrated balun and tuning element for DTV applications. The proposed technique is a unique tuning mechanism that is straddled between the gap of the proposed dipole antenna. This enables the frequency range of the dipole antenna to be adjusted to tightly cover the specified Digital TV band, thereby mitigating interference from signals outside the band that would otherwise degrade the quality of the DTV signal. The measured results confirm that the proposed antenna covers an impedance bandwidth of 414.5 MHz from 457.7 to 872.2 MHz, which covers the frequency band of DTV systems (470–862 MHz). Furthermore, the proposed antenna has excellent omnidirectional radiation with a maximum realized gain of 2.95 dBi. These results demonstrate the suitability of the antenna for DTV applications.

A new algorithm for location parameter estimation in DTV ground broadcast network

In the city, terrestrial digital TV network is the most perfect TV network, so the location of terrestrial broadcast signal based on digital TV has become one of the research hots-pots in recent years. Because multi-path in DTV wireless channel will cause serious signal fading, it becomes more difficult to detect DTV signal in the process of positioning, which directly affects the accuracy of positioning. Therefore, how to improve the detection accuracy of DTV signal through parameter estimation has become the focus of this paper. Based on the detailed study of DTV system based on wireless transmission channel characteristics and system structure, through the analysis based on linear least square (LS) channel estimation algorithm, the advantages and disadvantages of interference elimination is given based on the data, a new method of channel estimation, the simulation results verify the algorithm presented in this paper can well improve the channel estimation performance.

Compact Ultra-Wide-Band HI Monopole Antenna Loaded with C-Shaped Parasitic Elements for DVB-T and LTE Applications

In this study, a compact ultra-wide band microstrip antenna loaded with C-shaped parasitic elements, for Digital Video Broadcasting – Terrestrial (DVB-T) and LTE 450 / 700 signal reception, is presented. The proposed antenna is named “HI Monopole”, and its geometry has been designed to be simple and intuitive, lightweight, compact, possessing a low fabrication cost as well as an easy installation process inside electronic gadgets. The HI Monopole operates with ultra-wide bandwidth characteristics for operation within Digital Video Broadcasting – Terrestrial (DVB-T) standard, 470–890 MHz, that has been accomplished by: inserting an indent in its ground plane, adjusting the dimension of the feeding line, and adding two C-shaped parasite elements onto the region posterior to the antenna’s main irradiating element. It was verified through electromagnetic measuring that this device is capable of covering the 429-1022 MHz range, thus having 593 MHz of bandwidth. The superior and inferior cutoff frequencies have been chosen as the values in –10 dB of the device’s return loss. Therefore, the proposed antenna can be utilized in DTV and LTE signal reception through broadcasting in any country, independently of its adopted standard.

A Practical Measurement Method of the Occupied Bandwidth for 8-VSB DTV Signal Using Modified ACPR

A Practical Measurement Method of the Occupied Bandwidth for 8-VSB DTV Signal Using Modified ACPR

A Diversity Receiver-Based High-Gain Broad-Beam Reception Array Antenna

A novel reception antenna configuration is proposed for achieving high gain and broad beam coverage at the same time. This is accomplished by combining a multibeam array antenna with a diversity receiver. Signals from different beams are merged by diversity receiver in the baseband level using the maximal ratio combining scheme. The proposed approach is implemented by integrating a dual-channel digital TV receiver, a four-dipole array, and a 4 × 4 Butler matrix. Two outputs of the array, which have beam maxima pointing away from the boresight by ±14°, are connected to the two receiver inputs. Sensitivity measurements are conducted for different incident angles to find lowest transmitter power levels permissible for DTV signal demodulation. Measured results of a reference single-beam antenna validates that its angular sensitivity profile is proportional to the antenna gain pattern, and the ones of the diversity receiver-based array confirm that the proposed method can combine receptions of the two beams coherently. The effective 3 dB beamwidth of the implemented antenna is doubled, and the gain maximum is comparable with the single-beam array.

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.

A Cognitive Radio Spectrum Sensing Algorithm to Improve Energy Detection at Low SNR

Energy detection is among the most popular spectrum sensing method for spectrum sensing due its low complexity. Unfortunately, its performance is poor at low SNR. In this paper we proposed a spectrum sensing method for cognitive radio network that improves the performance of energy detection. The proposed method based on distribution analysis using kurtosis as test statistic. This comes from the fact that distribution of received signal when a channel is occupied will be different from vacant channel. Noise tends to have a Gaussian distribution. Signal which faces multipath fading during the transmission way will have non Gaussian distribution. Sensing algorithm was tested using captured DTV signal. Result shows that our method performs well at low SNR. It achieves probability of detection of 90 % for 10 % Probability of false alarm for low SNR, below -20 dB.

멀티콥터를 이용한 수직방향 DTV 신호 레벨 측정

DTV 필드 테스트는 실내와 실외에서 전계강도와 수신 가능성 등을 측정하는 것으로 실외의 경우 측정 차량을 도로에서 수평적으로 이동하면서 9m 높이의 안테나를 사용 DTV 신호를 측정하였다. 현대의 고층 빌딩과 같은 수직 집단 구조의 주거 형태에서는 수직적인 DTV 신호 측정을 통하여 수직 방향 전파 환경 분석이 필요하다. 특히 전면에 장애물이 많아 다중 경로 간섭과 임펄스 잡음의 영향으로 전계강도가 수신 임계값인 <TEX>$43dB{\mu}V/m$</TEX> 이상인 경우에도 수신이 불가한 경우가 있어 건물 밀집지역이나 특수한 측정 환경에 적합한 필드 측정 및 분석이 절대적으로 필요하다. 이를 위하여 자유롭게 비행하면서 DTV 수신신호 레벨을 측정할 수 있는 비행체 옥토형 멀티콥터를 개발하고 시험을 거쳐 실용성 있게 성능을 개선하였다. 휴대형 소형 DTV 수신신호 레벨 측정기와 안테나 및 데이터 전송용 M/W 송신기 또는 녹화용 장비가 탑재되어 DTV 수신신호 레벨 측정이 가능한 이 멀티콥터를 이용하여 전파환경이 다른 3지역의 측정을 통해 신뢰성 검증과 실용성을 입증하였다. 수직 방향 수신신호 레벨 측정은 수직 방향 전파 환경 변화가 큰 장소, 고층 아파트 같은 집단적 수직 주거 형태, 도보나 차량으로 접근이 불가능한 지역 등 측정점의 특수한 환경에 적합한 데이터를 얻을 수 있어 기존의 수평적 필드 테스트에서는 접근하기 어려운 장소의 전파 변화 분석에 유용하게 사용할 수 있다. DTV field tests have been performed to measure field strength and to check reception ratio on indoor and outdoor sites. They use an antenna of 9m to measure DTV signal in case of outdoor measurement on the road. Modern skyscrapers require the analysis of vertical-directional wave propagation by measuring vertical-directional DTV signal. Even if the field strength is above the reception threshold of <TEX>$43dB{\mu}V/m$</TEX>, the reception is impossible in case of strong multi-path or high impulse noise. So, vertical-directional field measurement is essential in environment of tall buildings. In this paper, we developed an octo type multi-copter to measure vertical-directional DTV signal level. A compact and portable DTV signal level meter, an antenna, a microwave transmitter for data transmission, and a recording equipment are equipped in the multi-copter. Three different sites are selected to test the measurement system. Developed measurement system using the multi-copter is very useful in measuring vertical-directional DTV signal, especially in apartments, non-accessible area by vehicles, and forbidden areas.

ATSC DTV 방송용 중계기 궤환간섭 제거 성능 개선

본 논문에서는 ATSC DTV 시스템에서 독립적인 궤환간섭 제거기(Feedback Interference Canceller: FIC)를 가지는 등화형 디지털 동일채널 중계기(Equalization Digital On-Channel Repeater: EDOCR)의 궤환간섭 제거 성능 향상을 위한 새로운 구조의 FIC를 제안한다. FIC는 기준신호와 궤환되는 신호의 상관관계를 이용하여 궤환채널을 추정하는데, ATSC DTV 방송 신호는 신호의 상관관계 특성을 저해하는 DC 파일럿을 포함하고 있으므로 FIC로 하여금 정확한 궤환채널 추정을 수행하지 못하게 한다. 이러한 문제를 해결하기 위해, EDOCR과 FIC의 결합 구조에 기반하여 EDOCR에서 신호 재변조 시 DC 파일럿을 포함하지 않는 기준신호를 추가적으로 생성하여 궤환채널 추정에 사용하는 DC 파일럿 없는 기준신호 기반 FIC와 디지털 신호처리를 통해 입력신호들을 백색화하여 DC 파일럿을 제거한 후 궤환채널을 추정하는 백색화된 신호 영역 FIC를 제안한다. 모의실험을 통해, 제안된 두 FIC 구조 모두 기존의 상관관계 제거형 FIC에 비해 우수한 궤환간섭 제거 성능을 가짐을 보인다. We propose two feedback interference cancellers(FICs) to improve the performance of the equalization digital on-channel repeater(EDOCR) with the FIC for the ATSC DTV broadcasting system. The FIC estimates the feedback channel between Tx. and Rx. antennas of the repeater by cross-correlating the reference signal and the feedback signal. Since there is a DC pilot which ruins the white property of the ATSC DTV signals, the FIC cannot estimate the feedback channel accurately. To solve the problem, the structural method which uses an additional DC pilot free reference for feedback channel estimation and the algorithmic method based on the digital signal processing which whitens the ATSC DTV signals and performs the feedback cancellation in the whitened signal domain. Simulation results show that the proposed two FICs show better feedback cancellation performance than the conventional FIC.

Simulink Model Based Design and FPGA Implementation of Multi-Channel DTV Transmitter

This paper presents DTV transmitter design based on the SW/HW hybrid architecture. Parts of the DTV transmission algorithm with less computational complexity are processed by the SW module in PC whereas computationally intensive parts are processed by the HW module in FPGA. The two parts are interconnected by the high speed serial link. To provide the multi-channel DTV signal, we design an architecture where several DTV waveforms are generated simultaneously and combined in the digital domain. We propose a simulink based communication system design and verification methodology. This method reduces the design and verification time of the prototype system significantly and reduces the RTL coding and verification burden.

향상된 지상파 DTV 채널 프로파일 측정기술

ATSC terrestrial DTV system can support high data rates for HDTV(High Definition Television) service, but it suffers from significant performance degradation caused by multipath fading. Thus, it is necessary to analyze multipath fading effects in order to enhance the DTV reception performance. Generally, DTV channel profile can be obtained by auto-correlation between reference pseudo random signal and received DTV signal. However, in the ATSC terrestrial DTV system, the estimation performance of DTV channel profile may be decreased due to the VSB modulation features. In this paper, improved DTV channel profile measurement technique is analyzed and proposed.

Spectrum Sensing Algorithm Based on ATSC DTV Signal Structure

Abstract In order to improve spectrum utilization rate, people need a method to sense the spectrum hole. This article puts forward a spectrum sensing algorithm, which uses ATSC DTV signal structural characteristics. First, we should sample the input signal based on structural characteristics. Second, these signal samples should be separated into different sets and accumulate these samples. Third, we execute the correlation operation to accumulation result and synchronization. Finally, decision can be got by comparing the test statistics with threshold. According to the simulation result, we can get the conclusion that signal structural characteristics based on spectrum sensing method can realize spectrum sensing well enough.

Kasami sequence studies for DTV transmitter identification

The transmitter identification of the DTV systems becomes crucial nowadays. Transmitter identification (TxID, or transmitter fingerprinting) technique is used to detect, diagnose and classify the operating status of any radio transmitter of interest. A pseudo random sequence was proposed to be embedded into the DTV signal before transmission. Thus, the transmitter identification can be realized by invoking the cross-correlation functions between the received signal and the possible candidates of the pseudo random sequences. Gold sequences and Kasami sequences are two excellent candidates for the transmitter ID sequences as they provide a large family of nearly-orthogonal codes. In order to investigate the sensitivity of the transmitter identification to different topologies and different Kasami sequence lengths, we present the analysis here for four different geometric layouts, namely circular distribution, doubly concentric and circular distribution, square array and hexagonal tessellation under the ENG (electronic news gathering) crews¿ working environment. The coverage area and the lowest received signal-to-interference ratio are considered as two essential parameters for the multiple-transmitter identification. It turns out to be that the larger the Kasami sequence length, the larger the received signal- to-interference ratio. Our new analysis can be used to determine the required Kasami sequence length for a specific broadcasting coverage.

Augmented Data Transmission for the ATSC Terrestrial DTV System

In this paper, we propose a novel Augmented Data Transmission (ADT) system which can transmit an additional data stream in the Advanced Television Systems Committee (ATSC) terrestrial DTV system. The proposed ADT system can offer an additional data of rate up to a few megabits per second (Mbps) based on hierarchical modulation, DTV signal cancellation, and advanced error correction code. The proposed ADT system significantly enhances capability compared with the data transmission schemes used in the transmitter identification (TxID) system. Since the proposed ADT system uses the in-band hierarchical modulation, it does not require any additional RF spectrum to increase the data capacity in a 6 MHz RF channel. Meanwhile, the ADT system has negligible impact to legacy receivers, if the proposed ADT system is deployed over the frequency bands occupied by ATSC A/53 or A/153 services.

지상파방송 직접수신 환경 개선과 차세대방송을 위한 700MHz대역 주파수 활용 연구

본 논문에서는 최근 지상파방송의 직접수신자 감소와 정부의 700MHz대역 주파수(Ch.52~69)의 통신할애 계획 등 지상파방송이 가지고 있는 문제점과 위기의 해결방안으로 방송용주파수를 좀 더 효율적으로 활용하며 시청자가 쉽게 직접 수신할 수 있는 DTV방송 수신환경 개선 방법을 찾아보고, 난시청해소와 차세대방송에 필요한 주파수 소요량을 정량적으로 제시하였다. 특히 디지털전환 이후에 회수되는 700MHz대역(108MHz 주파수폭)을 UHDTV와 Full-HD 3DTV 등 고품질 영상기술과 SFN 전송기술에 적용하여 차세대방송환경을 조기에 구축함으로써 난시청해소와 시청자와 방송과 산업에 미치는 효과를 제시하였다. Recently, the direct terrestrial broadcasting reception has been reduced rapidly and not been improved even in digital broadcast environment. The distribution plan of 700MHz frequency band(Ch.52~69) will make the problem worse because the spectrum might be allocated to mobile communication use. In this paper, we investigated the efficient frequency usage for DTV signal reception improvement and next generation broadcasting. The frequency amount required for reception improvement and for next generation broadcasting service is presented. We estimated the beneficial effect when the spectrum(108MHz Frequency Width) is used for SFN transmission technology, UHDTV and Full-HD 3DTV.

Interference to digital broadband communications and spread spectrum communications

Interference from DTV signals to cellular 700 MHz wireless phones may limit their acceptance by the public. Such interference has been reported to the FCC. The interference mechanism involved is 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> order non-linearity of the analog front end of cellular phones. Interference to GPS signal reception has been documented by a Technical Working Group. The author believes that the mechanism is also 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> order non-linearity of the analog front end of GPS receivers. In both situations, RF selectivity and mixer linearity must be improved.

ANTENNA CHARACTERIZATION AND DETERMINATION OF PATH LOSS EXPONENTS FOR 677 MHZ CHANNEL USING FIXED AND PORTABLE DIGITAL TERRESTRIAL TELEVISION

This paper presents propagation measurements results using Integrated Services Digital Broadcast-Terrestrial (ISDB-T) to investigate the characteristics of 6MHz wideband Digital Terrestrial Television channel at 677MHz for flxed and portable reception. Empirical measurements were done at predetermined measurement points consisting of 21 radials for a total of 92 locations extending to 20 kilometers around the National Broadcasting Network (NBN) digital transmitter. Characterizations were conducted using antenna heights of 9m (flxed reception), 3m (flxed reception), and 1.5m (portable reception). Modulation Error Rate (MER), power received, fleld strength and delay proflles were captured to help characterize the channel in an urban area in and around Metro Manila at day time for temperatures ranging from 26 - C to 32 - C. Measured fleld strength was compared to NTC F(50;90) curves. Polynomial flt using least square errors was used to plot the fleld strength coverage of NBN. For large-scale fading, it is observed that signal power conforms to Log Normal distribution. The study helped identify problem sites within the coverage. These are locations within the coverage area or at the outskirts of the coverage area where DTV signal is not received at all. A more accurate description of the DTT channel will lead to a better design of the parts of the Digital Television system from the network to transmitting system and receiving equipment. Path loss exponents computed for the three antenna heights can be helpful in developing empirical prediction models.

Secure Cooperative Sensing in IEEE 802.22 WRANs Using Shadow Fading Correlation

Cooperative (or distributed) sensing has been recognized as a viable means to enhance the incumbent signal detection by exploiting the diversity of sensors. However, it is challenging to secure such distributed sensing due mainly to the unique features of dynamic spectrum access networks-openness of low-layer protocol stacks in software-defined radio devices and the absence of interactions/coordination between primary and secondary devices. To meet this challenge, we propose an attack-tolerant distributed sensing protocol (ADSP) for DTV signal detection in IEEE 802.22 WRANs, under which sensors in close proximity are grouped as a cluster, and sensors within a cluster cooperate to safeguard the integrity of sensing. The heart of ADSP is a novel filter based on shadow-fading correlation, by which the fusion center cross-validates reports from the sensors to identify and penalize abnormal sensing reports. By realizing this correlation filter, ADSP significantly reduces the impact of an attack on the performance of distributed sensing, while incurring minimal processing and communication overheads. ADSP also guarantees the detectability requirements of 802.22 to be met even with the presence of sensing report manipulation attacks by scheduling sensing within the framework of sequential hypothesis testing. The efficacy of ADSP is validated on a realistic 2D shadow-fading field. Our extensive simulation-based study shows that ADSP reduces the false-alarm rate by 99.2 percent while achieving 97.4 percent of maximum achievable detection rate, and meets the detection requirements of IEEE 802.22 in various attack scenarios.

Multi-channel DTV signal generator design using modified Farrow filter

This paper proposes a compact multi-channel DTV signal generator. To combine multi-channel signal sources in digital domain, the baseband signal is up-sampled and interpolated using the modified Farrow-type filter. We formulate the optimization problem and design the filter coefficients. The designed filter contains a small number of multipliers with more than 40dB sideband signal suppression capability.