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Harvard Biphase
Harvard biphase is a magnetic run length code for encoding magnetic tape. It is one of the formats employed in forming the digital bits of logic one and logic zero, along with non-return-to-zero (NRZ) and bipolar-return-to-zero (RZ) formats. Each bit in the Harvard biphase format undergoes change at its trailing edge and this transpires either from high to zero or zero to high independently of its value. FDR Harvard biphase has previously been used for digital flight data recorder (FDR) where 12-bit words per second are recorded onto magnetic tape using Harvard biphase code. The data are encoded in frames and each of these contains a snapshot of the avionics system in the aircraft. For Harvard biphase, a phase transition in the middle of the bit cell indicates that the bit is 1. No transaction indicates that the bit is 0. There is also a phase transition at the start of each bit cell. The ARINC 573 serves as a standard for FDRs that feature continuous data stream encoded in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Run-length Encoding
Run-length encoding (RLE) is a form of lossless data compression in which ''runs'' of data (consecutive occurrences of the same data value) are stored as a single occurrence of that data value and a count of its consecutive occurrences, rather than as the original run. As an imaginary example of the concept, when encoding an image built up from colored dots, the sequence "green green green green green green green green green" is shortened to "green x 9". This is most efficient on data that contains many such runs, for example, simple graphic images such as icons, line drawings, games, and animations. For files that do not have many runs, encoding them with RLE could increase the file size. RLE may also refer in particular to an early graphics file format supported by CompuServe for compressing black and white images, that was widely supplanted by their later Graphics Interchange Format (GIF). RLE also refers to a little-used image format in Windows 3.x that is saved with the file ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flight Recorder
A flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of aviation accidents and incidents. The device may often be referred to colloquially as a "black box", an outdated name which has become a misnomer—they are now required to be painted bright orange, to aid in their recovery after accidents. There are two types of flight recording devices: the flight data recorder (FDR) preserves the recent history of the flight through the recording of dozens of parameters collected several times per second; the cockpit voice recorder (CVR) preserves the recent history of the sounds in the cockpit, including the conversation of the pilots. The two devices may be combined into a single unit. Together, the FDR and CVR objectively document the aircraft's flight history, which may assist in any later investigation. The two flight recorders are required by international regulation, overseen by the International Civil Aviat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
