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Digicipher 2
DigiCipher 2, or simply DCII, is a proprietary standard format of digital signal transmission and it doubles as an encryption standard with MPEG-2/MPEG-4 signal video compression used on many communications satellite television and audio signals. The DCII standard was originally developed in 1997 by General Instrument, which then became the Home and Network Mobility division of Motorola, then bought by Google in Aug 2011, and lastly became the Home portion of the division to Arris. The original attempt for a North American digital signal encryption and compression standard was DigiCipher 1, which was used most notably in the now-defunct PrimeStar medium-power direct broadcast satellite (DBS) system during the early 1990s. The DCII standard predates wide acceptance of DVB-based digital terrestrial television compression (although not cable or satellite DVB) and therefore is incompatible with the DVB standard. Approximately 70% of newer first-generation digital cable networks in Nort ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encryption
In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decipher a ciphertext back to plaintext and access the original information. Encryption does not itself prevent interference but denies the intelligible content to a would-be interceptor. For technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm. It is possible to decrypt the message without possessing the key but, for a well-designed encryption scheme, considerable computational resources and skills are required. An authorized recipient can easily decrypt the message with the key provided by the originator to recipients but not to unauthorized users. Historically, various forms of encryption have been used to aid in cryptography. Early encryption techniques were often used in mil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuner (television)
A tuner is a subsystem that receives radio frequency (RF) transmissions, such as FM broadcasting, and converts the selected carrier frequency and its associated bandwidth into a fixed frequency that is suitable for further processing, usually because a lower frequency is used on the output. Broadcast FM/ AM transmissions usually feed this intermediate frequency (IF) directly into a demodulator that converts the radio signal into audio-frequency signals that can be fed into an amplifier to drive a loudspeaker. More complex transmissions like PAL/NTSC (TV), DAB (digital radio), DVB-T/DVB-S/DVB-C (digital TV) etc. use a wider frequency bandwidth, often with several subcarriers. These are transmitted inside the receiver as an intermediate frequency (IF). Subcarriers are then processed like real radio transmissions, but the whole bandwidth is sampled with an analog-to-digital converter (A/D) at a rate faster than the Nyquist rate (that is, at least twice the IF frequency). A tune ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1997 Introductions
File:1997 Events Collage.png, From left, clockwise: The movie set of ''Titanic'', the highest-grossing movie in history at the time; ''Harry Potter and the Philosopher's Stone'', is published; Comet Hale-Bopp passes by Earth and becomes one of the most observed comets of the 20th century; Golden Bauhinia Square, where sovereignty of Hong Kong is handed over from the United Kingdom to the People's Republic of China; the 1997 Central European flood kills 114 people in the Czech Republic, Poland, and Germany; Korean Air Flight 801 crashes during heavy rain on Guam, killing 229; Mars Pathfinder and Sojourner land on Mars; flowers left outside Kensington Palace following the death of Diana, Princess of Wales, in a car crash in Paris., 300x300px, thumb rect 0 0 200 200 Titanic (1997 film) rect 200 0 400 200 Harry Potter rect 400 0 600 200 Comet Hale-Bopp rect 0 200 300 400 Death of Diana, Princess of Wales rect 300 200 600 400 Handover of Hong Kong rect 0 400 200 600 Mars Pathfinder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Rights Management Systems
Digital usually refers to something using discrete digits, often binary digits. Technology and computing Hardware *Digital electronics, electronic circuits which operate using digital signals **Digital camera, which captures and stores digital images ***Digital versus film photography **Digital computer, a computer that handles information represented by discrete values **Digital recording, information recorded using a digital signal Socioeconomic phenomena *Digital culture, the anthropological dimension of the digital social changes *Digital divide, a form of economic and social inequality in access to or use of information and communication technologies *Digital economy, an economy based on computing and telecommunications resources Other uses in technology and computing *Digital data, discrete data, usually represented using binary numbers *Digital marketing, search engine & social media presence booster, usually represented using online visibility. *Digital media, media sto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Television Terminology
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, entertainment, news, and sports. Television became available in crude experimental forms in the late 1920s, but only after several years of further development was the new technology marketed to consumers. After World War II, an improved form of black-and-white television broadcasting became popular in the United Kingdom and the United States, and television sets became commonplace in homes, businesses, and institutions. During the 1950s, television was the primary medium for influencing public opinion.Diggs-Brown, Barbara (2011''Strategic Public Relations: Audience Focused Practice''p. 48 In the mid-1960s, color broadcasting was introduced in the U.S. and most other developed countries. The availability of various types of archival storag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Television
Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advancement and represented the first significant evolution in television technology since color television in the 1950s. Modern digital television is transmitted in high-definition television (HDTV) with greater resolution than analog TV. It typically uses a widescreen aspect ratio (commonly 16:9) in contrast to the narrower format of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit up to seven channels in the same bandwidth as a single analog channel, and provides many new features that analog television cannot. A transition from analog to digital broadcasting began around 2000. Different digital television broadcasting standards have been adopted in different parts of the world; below are the more wid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptographic Protocols
A security protocol (cryptographic protocol or encryption protocol) is an abstract or concrete protocol that performs a security-related function and applies cryptographic methods, often as sequences of cryptographic primitives. A protocol describes how the algorithms should be used and includes details about data structures and representations, at which point it can be used to implement multiple, interoperable versions of a program. Cryptographic protocols are widely used for secure application-level data transport. A cryptographic protocol usually incorporates at least some of these aspects: * Key agreement or establishment * Entity authentication * Symmetric encryption and message authentication material construction * Secured application-level data transport * Non-repudiation methods * Secret sharing methods * Secure multi-party computation For example, Transport Layer Security (TLS) is a cryptographic protocol that is used to secure web (HTTPS) connections. It has an en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dolby Digital
Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995, the audio compression is lossy (except for Dolby TrueHD), based on the modified discrete cosine transform (MDCT) algorithm. The first use of Dolby Digital was to provide digital sound in cinemas from 35 mm film prints; today, it is also used for applications such as TV broadcast, radio broadcast via satellite, digital video streaming, DVDs, Blu-ray discs and game consoles. The main basis of the Dolby AC-3 multi-channel audio coding standard is the modified discrete cosine transform (MDCT), a lossy audio compression algorithm. It is a modification of the discrete cosine transform (DCT) algorithm, which was first proposed by Nasir Ahmed in 1972 and was originally intended for image compression. The DCT was adapted into the modified discrete cosine transform ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huffman Coding
In computer science and information theory, a Huffman code is a particular type of optimal prefix code that is commonly used for lossless data compression. The process of finding or using such a code proceeds by means of Huffman coding, an algorithm developed by David A. Huffman while he was a Sc.D. student at MIT, and published in the 1952 paper "A Method for the Construction of Minimum-Redundancy Codes". The output from Huffman's algorithm can be viewed as a variable-length code table for encoding a source symbol (such as a character in a file). The algorithm derives this table from the estimated probability or frequency of occurrence (''weight'') for each possible value of the source symbol. As in other entropy encoding methods, more common symbols are generally represented using fewer bits than less common symbols. Huffman's method can be efficiently implemented, finding a code in time linear to the number of input weights if these weights are sorted. However, althou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Channel
In most telecommunications organizations, a virtual channel is a method of remapping the ''program number'' as used in H.222 Program Association Tables and Program Mapping Tables to a channel number that can be entered via digits on a receiver's remote control. Often, "virtual channels" are implemented in digital television, helping users to find a desired channel easily, or easing the transition from analogue to digital broadcasting in general. The practice of assigning virtual channels is most common in those parts of the world where TV stations were colloquially named after the RF channel they were transmitting on ("Channel 6 Springfield"), as it was common in North America during the analogue TV era. In other parts of the world, such as Europe, virtual channels are rarely used or needed, as TV stations there identify themselves by name, not by RF channel or callsign. A "virtual channel" was first used for DigiCipher 2 in North America. It was later used and referred to as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Program And System Information Protocol
The Program and System Information Protocol (PSIP) is the MPEG (a video and audio industry group) and privately defined program-specific information originally defined by General Instrument for the DigiCipher 2 system and later extended for the ATSC digital television system for carrying metadata about each channel in the broadcast MPEG transport stream of a television station and for publishing information about television programs so that viewers can select what to watch by title and description. Its FM radio equivalent is Radio Data System (RDS). Function PSIP defines virtual channels and content ratings, as well as electronic program guides with titles and (optionally) descriptions to be decoded and displayed by the ATSC tuner. PSIP can also send: * the exact time referenced to UTC and GPS time; * the short name, which some stations use to publish their callsign. A maximum of seven characters can be used in a short name. PSIP is defined in ATSC standard A/65, the most re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
