MPEG-1 is a standard for lossy compression of video and audio. Today, MPEG-1 has become the most widely compatible lossy audio/video format in the world, perhaps the best-known part of the MPEG-1 standard is the MP3 audio format it introduced. The MPEG-1 standard is published as ISO/IEC11172 – Information technology—Coding of moving pictures, MPEG was formed to address the need for standard video and audio formats, and to build on H.261 to get better quality through the use of more complex encoding methods. Development of the MPEG-1 standard began in May 1988, fourteen video and fourteen audio codec proposals were submitted by individual companies and institutions for evaluation. The codecs were extensively tested for computational complexity and subjective quality and this specific bitrate was chosen for transmission over T-1/E-1 lines and as the approximate data rate of audio CDs. The codecs that excelled in testing were utilized as the basis for the standard and refined further, with additional features.
The reported completion date of the MPEG-1 standard varies greatly, a complete draft standard was produced in September 1990. The draft standard was publicly available for purchase, the standard was finished with the 6 November 1992 meeting. The Berkeley Plateau Multimedia Research Group developed an MPEG-1 decoder in November 1992, due in part to the similarity between the two codecs, the MPEG-2 standard includes full backwards compatibility with MPEG-1 video, so any MPEG-2 decoder can play MPEG-1 videos. This means that MPEG-1 coding efficiency can vary depending on the encoder used. The first three parts of ISO/IEC11172 were published in August 1993, the ISO patent database lists one patent for ISO11172, US4,472,747, which expired in 2003. The near-complete draft of the MPEG-1 standard was publicly available as ISO CD11172 by December 6,1991, a May 2009 discussion on the whatwg mailing list mentioned US5,214,678 patent as possibly covering MPEG audio layer II. Filed in 1990 and published in 1993, this patent is now expired, most popular software for video playback includes MPEG-1 decoding, in addition to any other supported formats.
The popularity of MP3 audio has established a massive installed base of hardware that can play back MPEG-1 Audio, virtually all digital audio devices can play back MPEG-1 Audio. Many millions have been sold to-date, before MPEG-2 became widespread, many digital satellite/cable TV services used MPEG-1 exclusively. The widespread popularity of MPEG-2 with broadcasters means MPEG-1 is playable by most digital cable and satellite set-top boxes, MPEG-1 was used for full-screen video on Green Book CD-i, and on Video CD. The Super Video CD standard, based on VCD, uses MPEG-1 audio exclusively, the DVD-Video format uses MPEG-2 video primarily, but MPEG-1 support is explicitly defined in the standard. The DVD-Video standard originally required MPEG-1 Layer II audio for PAL countries, MPEG-1 Layer II audio is still allowed on DVDs, although newer extensions to the format, like MPEG Multichannel, are rarely supported
NASA Deep Space Network
It performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected Earth-orbiting missions. DSN is part of the NASA Jet Propulsion Laboratory, similar networks are run by Europe, China and Japan. DSN currently consists of three deep-space communications facilities placed approximately 120 degrees apart around the Earth and they are, the Goldstone Deep Space Communications Complex outside Barstow, California. Each facility is situated in semi-mountainous, bowl-shaped terrain to shield against radio frequency interference. All DSN antennas are steerable, high-gain, parabolic reflector antennas, the antennas and data delivery systems make it possible to, acquire telemetry data from spacecraft. Perform Very Long Baseline Interferometry observations, measure variations in radio waves for radio science experiments. Monitor and control the performance of the network, the antennas at all three DSN Complexes communicate directly with the Deep Space Operations Center located at the JPL facilities in Pasadena, California.
In the early years, the control center did not have a permanent facility. It was a setup with numerous desks and phones installed in a large room near the computers used to calculate orbits. In July 1961, NASA started the construction of the permanent facility, the facility was completed in October 1963 and dedicated on May 14,1964. In the initial setup of the SFOF, there were 31 consoles,100 closed-circuit television cameras, the operations center personnel at SFOF monitor and direct operations, and oversee the quality of spacecraft telemetry and navigation data delivered to network users. Tracking vehicles in space is quite different from tracking missions in low Earth orbit. Deep space missions are visible for long periods of time from a portion of the Earths surface. These few stations, require huge antennas, ultra-sensitive receivers, Deep space is defined in several different ways. According to a 1975 NASA report, the DSN was designed to communicate with spacecraft traveling approximately 16,000 km from Earth to the farthest planets of the solar system.
JPL diagrams state that at an altitude of 30,000 km and this definition means that missions to the Moon, and the Earth–Sun Lagrangian points L1 and L2, are considered near space and cannot use the ITUs deep space bands. Other Lagrangian points may or may not be subject to rule due to distance. NASA was officially established on October 1,1958, to consolidate the separately developing space-exploration programs of the US Army, US Navy, the DSN was given responsibility for its own research and operation in support of all of its users
International Organization for Standardization
The International Organization for Standardization is an international standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promotes worldwide proprietary and it is headquartered in Geneva, and as of March 2017 works in 162 countries. It was one of the first organizations granted general consultative status with the United Nations Economic, ISO, the International Organization for Standardization, is an independent, non-governmental organization, the members of which are the standards organizations of the 162 member countries. It is the worlds largest developer of international standards and facilitates world trade by providing common standards between nations. Nearly twenty thousand standards have been set covering everything from manufactured products and technology to food safety, use of the standards aids in the creation of products and services that are safe, reliable and of good quality. The standards help businesses increase productivity while minimizing errors and waste, by enabling products from different markets to be directly compared, they facilitate companies in entering new markets and assist in the development of global trade on a fair basis.
The standards serve to safeguard consumers and the end-users of products and services, the three official languages of the ISO are English and Russian. The name of the organization in French is Organisation internationale de normalisation, according to the ISO, as its name in different languages would have different abbreviations, the organization adopted ISO as its abbreviated name in reference to the Greek word isos. However, during the meetings of the new organization, this Greek word was not invoked. Both the name ISO and the logo are registered trademarks, the organization today known as ISO began in 1926 as the International Federation of the National Standardizing Associations. ISO is an organization whose members are recognized authorities on standards. Members meet annually at a General Assembly to discuss ISOs strategic objectives, the organization is coordinated by a Central Secretariat based in Geneva. A Council with a membership of 20 member bodies provides guidance and governance.
The Technical Management Board is responsible for over 250 technical committees, ISO has formed joint committees with the International Electrotechnical Commission to develop standards and terminology in the areas of electrical and electronic related technologies. Information technology ISO/IEC Joint Technical Committee 1 was created in 1987 to evelop, maintain, ISO has three membership categories, Member bodies are national bodies considered the most representative standards body in each country. These are the members of ISO that have voting rights. Correspondent members are countries that do not have their own standards organization and these members are informed about ISOs work, but do not participate in standards promulgation. Subscriber members are countries with small economies and they pay reduced membership fees, but can follow the development of standards
The Hewlett-Packard Company or shortened to Hewlett-Packard was an American multinational information technology company headquartered in Palo Alto, California. The company was founded in a garage in Palo Alto by William Bill Redington Hewlett and David Dave Packard. HP was the worlds leading PC manufacturer from 2007 to Q22013 and it specialized in developing and manufacturing computing, data storage, and networking hardware, designing software and delivering services. HP had services and consulting business around its products and partner products.4 billion in 2008, in November 2009, HP announced the acquisition of 3Com, with the deal closing on April 12,2010. On April 28,2010, HP announced the buyout of Palm, on September 2,2010, HP won its bidding war for 3PAR with a $33 a share offer, which Dell declined to match. On October 6,2014, Hewlett-Packard announced plans to split the PC and printers business from its enterprise products, the split closed on November 1,2015, and resulted in two publicly traded companies, HP Inc.
and Hewlett Packard Enterprise. William Redington Hewlett and David Packard graduated with degrees in engineering from Stanford University in 1935. The company originated in a garage in nearby Palo Alto during a fellowship they had with a past professor, Terman was considered a mentor to them in forming Hewlett-Packard. In 1939, Packard and Hewlett established Hewlett-Packard in Packards garage with a capital investment of US$538. Hewlett and Packard tossed a coin to decide whether the company they founded would be called Hewlett-Packard or Packard-Hewlett, HP incorporated on August 18,1947, and went public on November 6,1957. Of the many projects they worked on, their very first financially successful product was an audio oscillator. This allowed them to sell the Model 200A for $54.40 when competitors were selling less stable oscillators for over $200, the Model 200 series of generators continued until at least 1972 as the 200AB, still tube-based but improved in design through the years. They worked on technology and artillery shell fuses during World War II.
Hewlett-Packards HP Associates division, established around 1960, developed semiconductor devices primarily for internal use and calculators were some of the products using these devices. HP partnered in the 1960s with Sony and the Yokogawa Electric companies in Japan to develop several high-quality products, the products were not a huge success, as there were high costs in building HP-looking products in Japan. HP and Yokogawa formed a joint venture in 1963 to market HP products in Japan, HP bought Yokogawa Electrics share of Hewlett-Packard Japan in 1999. HP spun off a company, Dynac, to specialize in digital equipment. The name was picked so that the HP logo hp could be turned upside down to be a reverse image of the logo dy of the new company
Phase-shift keying is a digital modulation scheme that conveys data by changing the phase of a reference signal. The modulation occurs by varying the sine and cosine inputs at a precise time and it is widely used for wireless LANs, RFID and Bluetooth communication. Any digital modulation scheme uses a number of distinct signals to represent digital data. PSK uses a number of phases, each assigned a unique pattern of binary digits. Usually, each phase encodes a number of bits. Each pattern of bits forms the symbol that is represented by the particular phase and this requires the receiver to be able to compare the phase of the received signal to a reference signal — such a system is termed coherent. Alternatively, instead of operating with respect to a constant reference wave, changes in phase of a single broadcast waveform can be considered the significant items. In this system, the demodulator determines the changes in the phase of the signal rather than the phase itself. Since this scheme depends on the difference between successive phases, it is termed differential phase-shift keying, in exchange, it produces more erroneous demodulation.
In the case of PSK, the phase is changed to represent the data signal, a convenient method to represent PSK schemes is on a constellation diagram. This shows the points in the plane where, in this context. Such a representation on perpendicular axes lends itself to straightforward implementation, the amplitude of each point along the in-phase axis is used to modulate a cosine wave and the amplitude along the quadrature axis to modulate a sine wave. By convention, in-phase modulates cosine and quadrature modulates sine, in PSK, the constellation points chosen are usually positioned with uniform angular spacing around a circle. This gives maximum phase-separation between adjacent points and thus the best immunity to corruption and they are positioned on a circle so that they can all be transmitted with the same energy. In this way, the moduli of the numbers they represent will be the same. Two common examples are binary phase-shift keying which uses two phases, and quadrature phase-shift keying which uses four phases, although any number of phases may be used.
Since the data to be conveyed are usually binary, the PSK scheme is designed with the number of constellation points being a power of 2. It is a form of the complementary Gaussian error function
JPEG is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between size and image quality. JPEG typically achieves 10,1 compression with little loss in image quality. JPEG compression is used in a number of file formats. These format variations are not distinguished, and are simply called JPEG. The term JPEG is an initialism/acronym for the Joint Photographic Experts Group, the MIME media type for JPEG is image/jpeg, except in older Internet Explorer versions, which provides a MIME type of image/pjpeg when uploading JPEG images. JPEG files usually have an extension of. jpg or. jpeg. JPEG/JFIF supports a maximum size of 65, 535×65,535 pixels. JPEG stands for Joint Photographic Experts Group, the name of the committee created the JPEG standard. The Joint stood for ISO TC97 WG8 and CCITT SGVIII, in 1987 ISO TC97 became ISO/IEC JTC1 and in 1992 CCITT became ITU-T.
Currently on the JTC1 side JPEG is one of two sub-groups of ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 1 – titled as Coding of still pictures, on the ITU-T side ITU-T SG16 is the respective body. The original JPEG group was organized in 1986, issuing the first JPEG standard in 1992, which was approved in September 1992 as ITU-T Recommendation T.81 and in 1994 as ISO/IEC 10918-1. The JPEG standard specifies the codec, which defines how an image is compressed into a stream of bytes and decompressed back into an image, the Exif and JFIF standards define the commonly used file formats for interchange of JPEG-compressed images. JPEG standards are formally named as Information technology – Digital compression, ISO/IEC10918 consists of the following parts, Ecma International TR/98 specifies the JPEG File Interchange Format, the first edition was published in June 2009. The JPEG compression algorithm is at its best on photographs and paintings of scenes with smooth variations of tone.
For web usage, where the amount of used for an image is important. JPEG/Exif is the most common format saved by digital cameras, on the other hand, JPEG may not be as well suited for line drawings and other textual or iconic graphics, where the sharp contrasts between adjacent pixels can cause noticeable artifacts. Such images may be saved in a lossless graphics format such as TIFF, GIF, PNG
A Mars rover is an automated motor vehicle that propels itself across the surface of the planet Mars upon arrival. There have been four successful robotically operated Mars rovers, the Jet Propulsion Laboratory managed the Mars Pathfinder mission and its now inactive Sojourner rover. It currently manages the Mars Exploration Rover missions active Opportunity rover and inactive Spirit, and, as part of the Mars Science Laboratory mission, the search for evidence of habitability and organic carbon on the planet Mars is now a primary NASA objective. Several rovers have been sent to Mars, Mars 2, Prop-M rover,1971, the Mars 2 and 3 spacecraft from the USSR had identical 4.5 kg Prop-M rovers. They were to move on skis while connected to the landers with cables, Mars 3, Prop-M rover,1971, lost when Mars 3 lander stopped communicating about 20 seconds after landing. Sojourner rover, Mars Pathfinder, landed successfully on July 4,1997, communications were lost on September 27,1997. Beagle 2, Planetary Undersurface Tool, lost with Beagle 2 on deployment from Mars Express in 2003. A compressed spring mechanism was designed to allow movement across the surface at a rate of 1 cm per 5 seconds and to burrow into the ground and collect a subsurface sample in a cavity in its tip.
Spirit, Mars Exploration Rover, launched on June 10,2003 at 13,58,47 EDT, nearly 6 years after the original mission limit, Spirit had covered a total distance of 7.73 km but its wheels became trapped in sand. Around January 26,2010, NASA conceded defeat in its efforts to free the rover, the last communication received from the rover was on March 22,2010, and NASA ceased attempts to re-establish communication on May 25,2011. Opportunity, Mars Exploration Rover, launched on July 7,2003 at 23,18,15 EDT, Opportunity is still operational and mobile as of April 7,2017. Curiosity, Mars Science Laboratory, by NASA, was launched November 26,2011 at 10,02 EST, Curiosity Rover is still operational as of April 7,2017. Mars rovers in development include, ExoMars, by the ESA, the rover will use stained glass to prevent UV from changing image colors, allowing for true color images of the surface of Mars. Chinese Mars Rover, has planned for a pre-2020 launch. MESR, REX, and MRPTA have a destination of Mars.
Mars 2020, a NASA rover based on the current rover Curiosity,2020 Chinese Mars Mission, would include an orbiter and small rover. One experimental design, not proposed for any mission, is, Mars Tumbleweed Rover. Many Mars Design Reference Mission include rovers as do some Mars sample return Astrobiology Field Laboratory, Mars Astrobiology Explorer-Cacher, cancelled 2011 Mars Surveyor 2001 rover, NASA distinguishes between mission objectives and science objectives
President Dwight D. Eisenhower established NASA in 1958 with a distinctly civilian orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29,1958, disestablishing NASAs predecessor, the new agency became operational on October 1,1958. Since that time, most US space exploration efforts have led by NASA, including the Apollo Moon landing missions, the Skylab space station. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the agency is responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA shares data with various national and international such as from the Greenhouse Gases Observing Satellite. Since 2011, NASA has been criticized for low cost efficiency, from 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1.
In the early 1950s, there was challenge to launch a satellite for the International Geophysical Year. An effort for this was the American Project Vanguard, after the Soviet launch of the worlds first artificial satellite on October 4,1957, the attention of the United States turned toward its own fledgling space efforts. This led to an agreement that a new federal agency based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency was created in February 1958 to develop technology for military application. On July 29,1958, Eisenhower signed the National Aeronautics and Space Act, a NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA, earlier research efforts within the US Air Force and many of ARPAs early space programs were transferred to NASA. In December 1958, NASA gained control of the Jet Propulsion Laboratory, NASA has conducted many manned and unmanned spaceflight programs throughout its history.
Some missions include both manned and unmanned aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent unmanned to Jupiter, the experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for manned spaceflight. This was followed by a space capsule program, and in turn by a two-man capsule program. This goal was met in 1969 by the Apollo program, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, to date, NASA has launched a total of 166 manned space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude,260,000 feet. The X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force, the design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems
In signal processing, data compression, source coding, or bit-rate reduction involves encoding information using fewer bits than the original representation. Compression can be lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy, no information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information, the process of reducing the size of a data file is referred to as data compression. In the context of data transmission, it is called coding in opposition to channel coding. Compression is useful because it reduces resources required to store and transmit data, computational resources are consumed in the compression process and, usually, in the reversal of the process. Data compression is subject to a space–time complexity trade-off, Lossless data compression algorithms usually exploit statistical redundancy to represent data without losing any information, so that the process is reversible.
Lossless compression is possible because most real-world data exhibits statistical redundancy, for example, an image may have areas of color that do not change over several pixels, instead of coding red pixel, red pixel. The data may be encoded as 279 red pixels and this is a basic example of run-length encoding, there are many schemes to reduce file size by eliminating redundancy. The Lempel–Ziv compression methods are among the most popular algorithms for lossless storage, DEFLATE is a variation on LZ optimized for decompression speed and compression ratio, but compression can be slow. DEFLATE is used in PKZIP, and PNG, LZW is used in GIF images. LZ methods use a table-based compression model where table entries are substituted for repeated strings of data, for most LZ methods, this table is generated dynamically from earlier data in the input. The table itself is often Huffman encoded, current LZ-based coding schemes that perform well are Brotli and LZX. LZX is used in Microsofts CAB format, the best modern lossless compressors use probabilistic models, such as prediction by partial matching.
The Burrows–Wheeler transform can be viewed as a form of statistical modelling. The basic task of grammar-based codes is constructing a context-free grammar deriving a single string, sequitur and Re-Pair are practical grammar compression algorithms for which software is publicly available. In a further refinement of the use of probabilistic modelling. Arithmetic coding is a more modern coding technique that uses the mathematical calculations of a machine to produce a string of encoded bits from a series of input data symbols
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is referred to as the Red Planet because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet, Mars has two moons and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan, there are ongoing investigations assessing the past habitability potential of Mars, as well as the possibility of extant life.
Future astrobiology missions are planned, including the Mars 2020 and ExoMars rovers, liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is about 6⁄1000 that of the Earths, except at the lowest elevations for short periods. The two polar ice caps appear to be largely of water. The volume of ice in the south polar ice cap, if melted. On November 22,2016, NASA reported finding a large amount of ice in the Utopia Planitia region of Mars. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior, Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.91, which is surpassed only by Jupiter, the Moon, optical ground-based telescopes are typically limited to resolving features about 300 kilometers across when Earth and Mars are closest because of Earths atmosphere. Mars is approximately half the diameter of Earth with an area only slightly less than the total area of Earths dry land.
Mars is less dense than Earth, having about 15% of Earths volume and 11% of Earths mass, the red-orange appearance of the Martian surface is caused by iron oxide, or rust. It can look like butterscotch, other common colors include golden, tan. Like Earth, Mars has differentiated into a metallic core overlaid by less dense materials. Current models of its interior imply a core with a radius of about 1,794 ±65 kilometers, consisting primarily of iron and this iron sulfide core is thought to be twice as rich in lighter elements than Earths. The core is surrounded by a mantle that formed many of the tectonic and volcanic features on the planet
In signal processing, particularly digital image processing, ringing artifacts are artifacts that appear as spurious signals near sharp transitions in a signal. Visually, they appear as bands or ghosts near edges, they appear as echos near transients, particularly sounds from percussion instruments, most noticeable are the pre-echos. The term ringing is because the output signal oscillates at a rate around a sharp transition in the input. As with other artifacts, their minimization is a criterion in filter design, the main cause of ringing artifacts is due to a signal being bandlimited or passed through a low-pass filter, this is the frequency domain description. In terms of the domain, the cause of this type of ringing is the ripples in the sinc function. Mathematically, this is called the Gibbs phenomenon, there are related artifacts caused by other frequency domain effects, and similar artifacts due to unrelated causes. By definition, ringing occurs when a non-oscillating input yields an output, formally.
This occurs most severely when the response or step response of a filter has oscillations – less formally, if for a spike input, respectively a step input. Ringing most commonly refers to step ringing, and that will be the focus, thus overshoot is the first step of the phenomenon, while ringing is the second and subsequent steps. Due to this connection, the terms are often conflated. If one has a time invariant filter, one can understand the filter and ringing in terms of the impulse response, or in terms of its Fourier transform. The central example, and often what is meant by ringing artifacts, is the ideal low-pass filter, the sinc filter. This has an impulse response function, as illustrated above, and the step response – its integral. Turning to step response, the response is the integral of the impulse response, formally. Thus values of the response can be understood in terms of tail integrals of the impulse response. Assume that the integral of the impulse response is 1, so it sends constant input to the same constant as output – otherwise the filter has gain.
Step undershoot is equivalent to a tail integral being negative, in case the magnitude of the undershoot is the value of the tail integral. Regions where a response are below or above the x-axis are called lobes