UHF Television Research Articles

Empirical Pathloss Model Analysis of Television White Space in Lagos, Western Nigeria

To conduct feasible unlicensed communications in the television band, radio equipment must first identify transmission possibilities, or the proportion of the permitted spectrum for broadcasting services that is vacant at a given time in a particular location, which is referred to as Television White Space (TVWS). A drive test was conducted to determine the signal strength of three cell towers in three distinct areas of Lagos state (rural, suburban, and urban). The signal power parameters were measured in rural, urban, and suburban parts of Lagos in order to provide empirical values for the parameters that unlicensed radio devices can utilize to distinguish between vacant and occupied television channels in a real-world scenario. This research presents the results of field measurements in the UHF television band (470-860 MHz) conducted in Lagos. This work investigated and compared several propagation models (COST 231 model, Egli model, Okumura-Hata model, and Plain Earth model). The Standard Deviation Error (SDE), Root Mean Square Error (RMSE), and Mean Error (ME) analysis showed that the COST-231 Hata model is the optimal model for calculating path loss based on path loss exponents. This discovery led to the development of an improved model, the Oressuff TV model, which uses COST-231 Hata parameters to predict path loss in the 470–870 MHz spectrum for rural, urban, and suburban locations. From the result of Root Mean Square Error analysis, the proposed model predicted path loss in rural, urban, and suburban stations with low RMSE of 3.06dB, 3.08dB, and 1.19dB respectively. These figures indicate that the model optimization was successful, and that the Oressuff TV proposed model can estimate the path loss incurred by television signals with greater precision. Telecommunications firms may improve their service by utilizing the proposed model.

Design and Analysis of Circular Polarized Receiver Antenna as Video Stabilizer in UHF Television

Design and Analysis of Circular Polarized Receiver Antenna as Video Stabilizer in UHF Television

TV white spaces exploration for cognitive radio: taxonomy and research issues

In order to implement the interweave cognitive radio solutions, the research for finding sparsely utilized spectrum bands has revealed the VHF and UHF television broadcast bands, known as television white spaces (TVWS) as the foremost candidate. The TVWS quantification and throughput analysis conducted via several measurement attempts and field trials uncover various facets of the TVWS spectrum measurement. Consequently, the conclusions obtained may be processed to get a statistical knowledge about spectrum availability in a particular geographic region and hence utilized for spectrum management. This paper explores inherent methodologies used for TVWS assessment and provides a comprehensive overview of the TVWS regulatory norms, results obtained by TVWS measurement campaigns and field trials conducted worldwide. In addition, research issues, implementation challenges and future directions for TVWS measurement procedure are highlighted.

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.

Studies on Electric field strength distribution of uhf television signal propagation in Ekiti State. Nigeria.

Researchers have continued to carry-out work to determine the actual coverage area of some broadcasting stations and the level of signal strength variation with distance from the transmitter, which is useful for radio transmission designs.In Nigeria, few works exist on the frequency modulation (FM) signals propagation, and little work has been done on the television signals. The work determines the actual coverage of the Broadcasting Service of Ekiti State Television, in Ekiti - State, southwest Nigeria, with the expected coverage area being the entire land mass of the State. The method used is such that requires the physical presence of the investigator in all the towns and villages within the State with the necessary instrument to carry out the electric field strength measurements in all the locations.The variation of signal level with distance (i.e. Propagation curve) was analysed, to reveal areas of optimum coverage and areas that are poorly serviced.The coverage of the newly installed transmitter in the station was compared to the old transmitter (which had been in use for over 30 years), and a comprehensive statistical data base provided for the UHF television broadcasting Station. The results shows the field strength distribution of the broadcasting station in major towns and villages,its elevation pattern and the various grades of coverage enjoyed by its citizens in such locations. Recommendations were made on getting areas outside optimum coverage well serviced. Keywords: Coverage area, Reception, Signal strength variations, Transmission,Ultra high frequency.

Tecnologia radio cognitiva en la banda ultra high frequency (UHF)

Las empresas de comunicaciones celulares móvi­les en Colombia requieren mayor recurso espectral para ampliar su portafolio de servicios; sin embar­go, no hay frecuencias adicionales para tal fin, no obstante es conocido que existe infrautilización de muchas bandas licenciadas. Por esta razón nuevas tecnologías de radio son estudiadas para su imple-mentación en búsqueda de solucionar este proble­ma, ellas son: Radio Definida por Software (RDS ) [1], Radio Cognición (RC) [2] y Acceso Dinámico al Espectro (ADE) [3]. Estasestrategias proponen movilidad en todo el espectro de las comunicacio­nes de radio para suplir necesidades y lograr ma­yor eficiencia en la administración de dicho recur­so. Desde esta perspectiva se presenta un estudio de caso para examinar los requisitos que se deben cumplir para la implementación de una red de radio cognitiva en Bogotá, para lo cual se evaluó la po­sibilidad de migración de las comunicaciones ce­lulares desde sus bandas asignadas a las bandas de televisión UHF, y la coexistencia sin interferencias entre estos 2 servicios. El estudio arrojó viabilidad en dicha migración; sin embargo, la implementa-ción de radio cognitiva compromete voluntades de los operadores y del Ministerio de Tecnologías de la Información y las Comunicaciones de Colom­bia, y demanda disponibilidad de hardware, soft­ware y plataformas de radio flexibles.

日本海上におけるUHF放送波の見通し外伝搬と天候との相関

Recently, the electromagnetic environment in the UHF television band has changed significantly in Japan. Digital broadcasting has spread, but radio disturbance occur from spring to fall. This phenomenon is caused by ionospheric propagation of the Es layer or duct propagation in the troposphere. We have steadily observed UHF radio waves at Ishikawa National College of Technology in Tsubata since 2005. UHF radio waves are received from Matsue city and Korea, which are over-the-horizon distances away from Tsubata. Therefore, we researched the relations between the wave receiving statuses of channels 41, 43, and 45 from Matsue city and the season and weather, and we found that we received the most radio waves in summer and in fine weather. Therefore, this phenomenon may be due to the duct propagations in the troposphere.

Potentialities and challenges of WiFi-based passive radar

In recent years the use of passive bistatic radar (PBR) for surveillance purposes has received renewed interest. A number of studies have looked at the use of different analogue signals such as FM radio and UHF television broadcasts, as well as digital transmissions such as DAB, DVB, and GSM. In the above applications, PBR is rapidly reaching a point of maturity. Basically, even though there are still many challenges to be solved involving both technology development and processing techniques, PBR practical feasibility for long-range surveillance purposes has been well established.

20-5 日本海を越えて到来するUHF・TV放送波の観測[II](第20部門無線光伝送)

20-5 日本海を越えて到来するUHF・TV放送波の観測[II](第20部門無線光伝送)

15-7 日本海を越えて到来するUHF・TV放送波の観測(第15部門 無線・光伝送2)

15-7 日本海を越えて到来するUHF・TV放送波の観測(第15部門 無線・光伝送2)

See Atlanta the Easy Way: APA-Sponsored Tours

See Atlanta the Easy Way: APA-Sponsored Tours

An Experiment with snow resistant of UHF Television Full Band Low-sidelobe Received Antenna

An Experiment with snow resistant of UHF Television Full Band Low-sidelobe Received Antenna

Small-signal nonlinear modeling of television IOTs

The inductive output tube (IOT) is a high power vacuum tube amplifier popularly used in UHF television broadcasting. A small-signal nonlinear model is presented for the IOT. Several simplifying assumptions are made to make the proposed model more tractable mathematically. Component values are then assigned to this simplified model based on measured IOT S/sub 11/ performance. This model is used to predict IOT intermodulation performance for a unique test case. The results predicted by the proposed model compare favorably to the real world measured results for the same test case.

Advances in SiC materials and devices: an industrial point of view

Silicon Carbide (SiC) is an emerging semiconductor that has proven itself especially well-suited to high temperature power switching and high-frequency power generation. In this paper we examine recent advances in materials development and device performance. In boule growth we have focused on increasing boule diameter and reducing defect counts. Two conductivity types have been developed (1) semi-insulating for MESFETs, and (2) highly conducting boules for SITs and power switches. Very uniform planetary multi-wafer epitaxial layer growth on these wafers is described, in which specular epitaxial layers have been obtained with growth rates of 3–5 μm h −1 exhibiting unintentional n-type doping of ∼1×10 15 cm −3, and room temperature Hall mobilities of ∼1000 cm 2 V −1 s −1. Controlled n-type doping between ∼5×10 15 cm −3 and >1×10 19 cm −3 has also been demonstrated using nitrogen doping. SiC finds application in high temperature power switching devices and microwave power transistors. MOS Turn-Off Thyristors (MTO™) are being investigated as power switches because they offer ease of turn-off, 500°C operation and reduced cooling requirements. In the fabrication of high-power, high-frequency transistors at UHF, L-, S-, and X-bands SiC has been found superior to both silicon and GaAs. For example, a 4H-SiC UHF television module has demonstrated good signal fidelity at the 2000 W PEP level, S-band transistor packages have shown 300 W peak power for radar applications, and 6 W power output has been obtained at X-Band.

THE 267 MHz HIGH POWER CW KLYSTRODE® AMPLIFIER

A 250 kW CW 267 MHz Klystrode has been designed and built as part of a major program in conjunction with the Chalk River National Labs., Chalk River, Ontario, Canada. The high CW power design has evolved from previous work for UHF television and the SDI program. A major step was taken on this program to simplify and reduce the complexity of the RF input circuit. CW power in excess of 250kW and efficiencies in excess of 70% were readily obtained with power gain in excess of 21 dB. Three tubes and associated circuitry were tested and delivered as part of the effort.

A 70 mile long-distance experimental broadcast of digital spectrum compatible high definition television

An experiment in which digital high definition television broadcasts originating at the facilities of UHF television station WMVT, channel 36, in Milwaukee, Wisconsin, were received at the facilities of Zenith Electronics Corporation in Glenview, Illinois, approximately 70 miles distant, is reported. The broadcasts used the Zenith/AT&T Digital Spectrum Compatible High Definition Television System proposed to the Federal Communications Commission Advisory Committee on Advanced Television. The digital signal was received at the 70 miles distance except for very infrequent intervals of fading in early experimentation. A mobile test vehicle 40 to 50 miles distant received the digital signal without error. Cochannel interference from a low-power television station was effectively suppressed. >

Using High Technology to Facilitate Educational Equity in Rural Northeastern Utah Schools

The northeastern Utah Telelearning Project began in 1985. A cooperative effort by the Northeastern Utah Educational Service Center, local school districts, and the Area Vocational Center pooled their resources and talents to identify alternative delivery methods for providing education to rural schools separated by geography and economic resources. Computers, telephones, dedicated phone lines, simplex and duplex microwave, and UHF television were used to provide classes to six area schools. These communication tools were shown to be effective methods of delivery when traditional means were no longer available. The planning, implementation, and operation of the telelearning system are examined.

Japan's Mainstream Press: Freedom to Conform?

T HE FREEDOM OF THE PRESS, along with other natural rights like of religion, assembly, and speech, is enshrined in Japan's political system by the 1947 constitution. Over the past forty years, unleashed by this right, a vast has emerged to satisfy the reading, viewing, and listening needs of one of the world's most literate populations. Japan has over 180 newspapers with a daily circulation of over 40 million, about 100 important weekly magazines with a combined yearly circulation of 1 billion, and about two thousand monthly magazines with a yearly circulation of 2 billion. In addition, there are 1,502 VHF and 9,453 UHF television stations, and 1,018 radio stations.' Althought the mass media is sometimes called the fourth branch of government, can one make meaningful generalizations about the political influence and orientation of the in Japan or any other liberal democratic country which guarantees freedom of the press? If the press is really free, would not the subsequent diversity of political views make any generalizations about the meaningless? Apparently most Japanese political groups not only believe there is a monolithic block called the media, but also ascribe to it vast political influence. A 1980 survey of eleven groups, which included business organizations, bureaucrats, Liberal Democratic Party members, farm organizations, media, intellectuals, labor unions, opposition parties, citizen movements, feminist groups, and the Buraku Liberation League, found that almost every group considered the to be the most influential group in Japanese society.2 The only exception was the which ranked itself second in importance while asserting that the bureaucrats were the most influential group. While united in their view that the was the most influential force in society, these groups strongly differed over the media's political orientation. The conservative groups consider the too far to the left, while leftist groups label the too far to the right.3

Interference Problems in Proposed Spectrum Sharing Between FM Land Mobile Radio and UHF Television

On June 20, 1985 under general Docket No. 85-172 the FCC issued a Notice of Proposed Rule Making entitled Further Sharing of the UHF Television Band by Private Land Mobile Radio Services.

Compact High Efficiency, Light Weight 200-800 MHz High Power RF Source

There has long been a need for a new more efficient less bulky high power RF power source to drive accelerators in the 200 to 800 MHz region. Results on a recent 5-year EIMAC sponsored R and D program which have lead to the introduction of the Klystrode for UHF television and troposcatter applications indicate that at power levels of 1MW or more efficiencies in excess of 75% can be obtained at 450 MHz. Efficiencies of this order coupled with potential size and weight parameters which coupled with potential size and weight parameters which are a fraction of those of existing high power UHF generators open up new applications which heretofore would have been impractical if not impossible. Measurements at 470 MHz on existing Klystrodes are given. Projected operating conditions for a 1MW 450 MHz Klystrode having an overall length of 60 inches and a total tube, circuit, and magnet weight of 250 pounds is presented.