|
Distributed Transmission System
In North American digital terrestrial television broadcasting, a distributed transmission system (DTS or DTx) is a form of single-frequency network in which a single broadcast signal is fed via microwave, landline, or communications satellite to multiple synchronised terrestrial radio transmitter sites. The signal is then simultaneously broadcast on the same frequency in different overlapping portions of the same coverage area, effectively combining many small transmitters to generate a broadcast area rivalling that of one large transmitter or to fill gaps in coverage due to terrain or localized obstacles. History While the idea of a single-frequency network of multiple transmitters broadcasting the same programming on the same channel from multiple transmitter sites is not a new concept, the ATSC digital television standard in use in North America was not designed for this mode of operation and was poorly adapted to these applications. The restrictive timing requirement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Digital Terrestrial Television
Digital terrestrial television (DTTV, DTT, or DTTB) is a technology for terrestrial television, in which television stations broadcast television content in a digital signal, digital format. Digital terrestrial television is a major technological advancement over analog television, and has largely replaced analog television broadcasting, which was previously in common use since the middle of the 20th century. Test broadcasts began in 1998, and the Digital television transition, changeover to digital television began in 2006 and is now complete in many countries. The advantages of digital terrestrial television are similar to those obtained by digitizing platforms such as cable TV, satellite, and telecommunications: more efficient use of radio spectrum bandwidth, the ability to broadcast more channels than analog, better quality images, and potentially lower operating costs for broadcasters. Different Country, countries have adopted different digital broadcasting standards. Some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
DVB-T
DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in February 1998. This system transmits compressed digital audio, digital video and other data in an MPEG transport stream, using coded orthogonal frequency-division multiplexing (COFDM or OFDM) modulation. It is also the format widely used worldwide (including North America) for Electronic News Gathering for transmission of video and audio from a mobile newsgathering vehicle to a central receive point. It is also used in the US by amateur television operators. Basics Rather than carrying one data carrier on a single radio frequency (RF) channel, COFDM works by splitting the digital data stream into a large number of slower digital streams, each of which digitally modulates a set of closely spaced adjacent sub-carrier frequencies. In the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Band I
Band I is a range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum. The first time there was defined "for simplicity" in Annex 1 of "Final acts of the European Broadcasting Conference in the VHF and UHF bands - Stockholm, 1961". Band I ranges from 47 to 68 MHz for the European Broadcasting Area, and from 54 to 88 MHz for the Americas and it is primarily used for television broadcasting in compliance with ITU Radio Regulations (article 1.38). With the transition to digital TV, most Band I transmitters have already been switched off. Television broadcasting usage Channel spacings vary from country to country, with spacings of 6, 7 and 8 MHz being common. In the UK, Band I was originally used by the BBC for monochrome 405-line television; likewise, the French former 455-line (1937–1939) then 441-line (1943–1956) transmitter on the Eiffel Tower in Paris, and some stations of the French monochrome 819-line system used Band I. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Altoona, Pennsylvania
Altoona ( ) is a city in Blair County, Pennsylvania, United States. The population was 43,963 at the time of the 2020 United States census, 2020 census. It is the principal city of the Altoona Metropolitan statistical area, metropolitan area, which includes all of Blair County and was recorded as having a population of 122,823. Altoona was established in 1849 by the Pennsylvania Railroad. Having grown around the railroad industry, the city has worked to recover from Deindustrialization, industrial decline and Urban sprawl, urban decentralization experienced in recent decades. The city is home to the Altoona Curve baseball team of the Eastern League (1938–present), Eastern League, which is the AA affiliate of the Pittsburgh Pirates Major League Baseball team. They play at Peoples Natural Gas Field in Altoona. The Altoona Symphony Orchestra has called Altoona home since 1928. Prominent landmarks include the Horseshoe Curve (Pennsylvania), Horseshoe Curve, the Railroaders Mem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Johnstown, Pennsylvania
Johnstown is the largest city in Cambria County, Pennsylvania, United States. The population was 18,411 as of the 2020 United States census, 2020 census. Located east of Pittsburgh, it is the principal city of the Metropolitan statistical area, Johnstown metropolitan area and had 133,472 residents in 2020. It is also part of the Johnstown–Somerset combined statistical area, which includes both Cambria and Somerset County, Pennsylvania, Somerset Counties. History Johnstown was settled in 1770. The city has experienced three major floods in its history. The Johnstown Flood of May 31, 1889, occurred after the South Fork Dam collapsed upstream from the city during heavy rains. At least 2,209 people died as a result of the flood and subsequent fire that raged through the debris. Another major flood occurred in 1936. Despite a pledge by President Franklin Delano Roosevelt to make the city flood free, and despite subsequent work to do so, another major flood occurred in 1977. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
State College, Pennsylvania
State College is a Borough (Pennsylvania), borough and Home rule municipality (Pennsylvania), home rule municipality in Centre County, Pennsylvania, United States. It is a college town, home to the University Park, Pennsylvania, University Park campus of Pennsylvania State University, The Pennsylvania State University. State College is the largest designated borough in Pennsylvania. It is the principal borough of the six municipalities that make up the Happy Valley (Pennsylvania), State College area, the largest settlement in Centre County, Pennsylvania, Centre County and one of the principal cities of the greater State College–DuBois, PA Combined Statistical Area, State College-DuBois Combined Statistical Area with a combined population of 236,577 as of the 2010 United States census, 2010 U.S. census. In the 2010 census, the borough population was 42,034. History Indigenous peoples The Lenape, Delaware, Iroquois, Mingo, and Shawnee were some of the first native inhabitants w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
WPSX-TV
WPSU-TV (channel 3) is a PBS member television station licensed to Clearfield, Pennsylvania, United States, serving West-Central Pennsylvania. Owned by the Pennsylvania State University as part of Penn State Public Media, it is sister to NPR member WPSU (91.5 FM) and student radio station WKPS ("The Lion 90.7 FM"). The three stations share studios at Innovation Park on Penn State's University Park campus in State College. WPSU-TV's primary transmitter is located north of Clearfield in Lawrence Township, with a secondary transmitter in Pine Grove Mills, Pennsylvania. History Penn State has a long history of using new media to extend access to education. It was the first American institution of higher education to offer agricultural correspondence courses in 1892. When radio became popular in the 1920s, the institution tried broadcasting courses and was the first U.S. university to experiment with closed-circuit television delivery in the 1940s. Penn State hosted a conferenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Pennsylvania State University
The Pennsylvania State University (Penn State or PSU) is a Public university, public Commonwealth System of Higher Education, state-related Land-grant university, land-grant research university with campuses and facilities throughout Pennsylvania, United States. Founded in 1855 as Farmers' High School of Pennsylvania, Penn State was named the state's first land-grant university eight years later, in 1863. Its primary campus, known as Penn State University Park, is located in State College, Pennsylvania, State College and College Township, Pennsylvania, College Township. Penn State enrolls more than 89,000 students, of which more than 74,000 are undergraduates and more than 14,000 are postgraduates. In addition to its land-grant designation, the university is a National Sea Grant College Program, sea-grant, National Space Grant College and Fellowship Program, space-grant, and one of only six Sun Grant Association, sun-grant universities. It is Carnegie Classification of Instit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
World Trade Center (1973–2001)
The original World Trade Center (WTC) was a complex of seven buildings in the Financial District, Manhattan, Financial District of Lower Manhattan in New York City. Built primarily between 1966 and 1975, it was dedicated on April 4, 1973, and was collapse of the World Trade Center, destroyed during the September 11 attacks in 2001. At the time of their completion, the 110-story-tall Twin Towers, including the original 1 World Trade Center (1970–2001), 1 World Trade Center (the North Tower) at , and 2 World Trade Center (1971–2001), 2 World Trade Center (the South Tower) at , were the History of the world's tallest buildings#Skyscrapers: tallest buildings since 1908, tallest buildings in the world; they were also the List of tallest twin buildings and structures, tallest twin skyscrapers in the world until 1996, when the Petronas Towers opened in Kuala Lumpur, Malaysia. Other buildings in the complex included the Marriott World Trade Center (3 WTC), 4 World Trade Center (197 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Reflected Signal
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The ''law of reflection'' says that for specular reflection (for example at a mirror) the angle at which the wave is incident on the surface equals the angle at which it is reflected. In acoustics, reflection causes echoes and is used in sonar. In geology, it is important in the study of seismic waves. Reflection is observed with surface waves in bodies of water. Reflection is observed with many types of electromagnetic wave, besides visible light. Reflection of VHF and higher frequencies is important for radio transmission and for radar. Even hard X-rays and gamma rays can be reflected at shallow angles with special "grazing" mirrors. Reflection of light Reflection of light is either ''specular'' (mirror-like) or ''diffuse'' (retaining the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Modulation
Signal modulation is the process of varying one or more properties of a periodic waveform in electronics and telecommunication for the purpose of transmitting information. The process encodes information in form of the modulation or message signal onto a carrier signal to be transmitted. For example, the message signal might be an audio signal representing sound from a microphone, a video signal representing moving images from a video camera, or a digital signal representing a sequence of binary digits, a bitstream from a computer. This carrier wave usually has a much higher frequency than the message signal does. This is because it is impractical to transmit signals with low frequencies. Generally, receiving a radio wave requires a radio antenna with a length that is one-fourth of the wavelength of the transmitted wave. For low frequency radio waves, wavelength is on the scale of kilometers and building such a large antenna is not practical. Another purpose of modulation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
