Digital Television Stations Research Articles

Phase Coherent EM Array Measurements in a Refractive Environment

Phase-coherent measurements of the pilot tone from a digital television (DTV) station were taken by a 24-element vertical array 168 km from the transmitter. Measurements were recorded over 15 days in Southern California, a region known for ducting events in which abnormal atmospheric refractivity patterns allow for the exceptionally long-range propagation of electromagnetic (EM) waves. The DTV station was positioned over the horizon (OTH) relative to the receiver array such that the line of sight was obstructed; thus, significant diffraction loss was expected. Direction-of-arrival (DOA) estimation was performed on the measurements. The measurement campaign objective was to collect the first long-term data set of DOA and the array-signal-to-noise ratio (ASNR) from signals propagating OTH through a refractive channel, toward the goal of enhancing the fidelity of atmospheric refractivity estimates. The analysis of the collected data shows that ASNR is correlated with atmospheric parameters related to refractivity.

Model of Quality Management of Education Digital Television Station in Thailand

Model of Quality Management of Education Digital Television Station in Thailand

Model of Quality Management of Education Digital Television Station in Thailand

Model of Quality Management of Education Digital Television Station in Thailand

Radio-Wave Propagation Model for UHF Band in Different Climatic Conditions with Dyadic Green’s Function

This article proposes a deterministic radio propagation model using dyadic Green's function to predict the value of the electric field. Dyadic is offered as an efficient mathematical tool which has symbolic simplicity and robustness, as well as taking account of the anisotropy of the medium. The proposed model is an important contribution for the UHF band because it considers climatic conditions by changing the constants of the medium. Most models and recommendations that include an approach for climatic conditions, are designed for satellite links, mainly Ku and Ka bands. The results obtained by simulation are compared and validated with data from a Digital Television Station measurement campaigns conducted in the Belem city in Amazon region during two seasons. The proposed model was able to provide satisfactory results by differentiating between the curves for dry and wet soil and these corroborate the measured data, (the RMS errors are between 2-5 dB in the case under study).

Coherent Passive Backscatter Communications Using Ambient Transmitters

A communications method is presented based on the backscatter modulation of incident radio frequency signals using low-complexity tags. The incident signals arise from digital television stations used as illuminators of opportunity. A receiver detects the tag using coherent processing algorithms similar to those used in passive radar, extending the detection range over published noncoherent techniques. This method enables shared use of the UHF television band for low-data-rate applications. While analyses suggest that rates exceeding 1 kbps might be achievable at 1 km range, experimental results demonstrate the challenges in designing and implementing such a system.

OPTIMAL LOCATION ANALYSIS OF LARGE-SCALE DIGITAL TELEVISION STATIONS BASED ON THE VORONOI DIAGRAM FOR ENVIRONMENTAL MONITORING

Optimal location selection for digital television stations is the most significant task in terrestrial broadcasting-TV covering net planning as well as in environmental monitoring. Based on the summary of mathematical model of digital television location, a method of optimal station location analysis based on Voronoi diagram is proposed in the paper. Firstly, the preprocessing is performed to create the forth buffer's boundary of polygon convex hull for achieving aided points of boundary interpolation with the 1:250000 terrain Database and digital elevation model with a resolution of 10m 10m. Then the initial positions are fixed with the location method of the largest hollow circular of Voronoi diagram. Furthermore, the location of stations is optimized with local reconstruction and Laplacian smoothing technology and evaluated by the quality assessment methods of triangulation and application. At last, the location of the new stations is readjusted based on the evaluated results and the factor of terrain and population. The method has effectively solved the overall planning problem of large-scale digital broadcasting location with the advantage of speediness, automatism and rationality.

Digital Television Station and Network Implementation

The comparatively recent introduction of digital transmission provides superior video and audio quality and increased capabilities for new services. However, for many years broadcast stations and networks have been transitioning to digital systems for various aspects of production and distribution. The introduction of digital TV has required further major changes to broadcast stations and networks, with large capital investments. This paper describes some of the considerations in implementing digital systems for studios and transmission, and compares broadcast service models adopted in various parts of the world.

The Dawn of Terrestrial Digital Television Broadcasting in the United States

AbstractWith over 50 digital television stations on the air and thousands of digital TV receivers sold, the dawn of terrestrial digital broadcasting has finally arrived. It is now almost 12 full years since the FCC issued its Notice of Inquiry concerning Advanced Television, and it is almost 4 years since the ATSC Digital Television Standard was published. But at long last the implementation of this very flexible standard is underway. The standard supports both high definition and standard definition video and surround‐sound. It will soon be supplemented by other ATSC standards that will enable pay‐TV and data broadcasting to be implemented. By the end of 1999 there will be over 120 digital TV stations on the air and, according to some estimates, nearly 200,000 digital receivers in use.