Digital Audio Tape
A 90-minute DAT cartridge, size compared to a AAA (LR03) battery. In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy
Media type	Magnetic tape
Capacity	120 minutes
Read mechanism	Rotating head
Write mechanism	Rotating head, helical scan
Developed by	Sony
Usage	Audio storage

Digital Audio Tape (DAT or R-DAT) is a signal recording and playback medium developed by Sony in the mid 1980s. Magnetic tape is a medium for Magnetic recording generally consisting of a thin magnetizable coating on a long and narrow strip of Plastic. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with The 1980s was the decade spanning from January 1 1980 to December 31 1989. In appearance it is similar to a compact audio cassette, using 4 mm magnetic tape enclosed in a protective shell, but is roughly half the size at 73 mm × 54 mm × 10. The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply tape, is a Magnetic tape sound Magnetic tape is a medium for Magnetic recording generally consisting of a thin magnetizable coating on a long and narrow strip of Plastic. 5 mm. As the name suggests the recording is digital rather than analog, DAT converting and recording at higher, equal or lower sampling rates than a CD (48, 44. A digital system uses discrete (discontinuous values usually but not always Symbolized Numerically (hence called "digital" to represent information for An analog or analogue signal is any continuous signal for which the time varying feature (variable of the signal is a representation of some other A Compact Disc (also known as a CD) is an Optical disc used to store digital data, originally developed for storing digital audio 1 or 32 kHz sampling rate, and 16 bits quantization). The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Sampling theorem The Nyquist–Shannon sampling theorem states that perfect reconstruction A bit is a binary digit, taking a value of either 0 or 1 Binary digits are a basic unit of Information storage and communication In Signal processing, quantization is the process of approximating a continuous range of values (or a very large set of possible discrete values by a relatively-small set of If a digital source is copied then the DAT will produce an exact clone, unlike other digital media such as Digital Compact Cassette or non-Hi-MD MiniDisc, both of which use lossy data compression. Digital Compact Cassette ( DCC) is an obsolete Magnetic tape sound recording format introduced by Philips and Matsushita in late 1992 A MiniDisc ( MD) is a Magneto-optical disc-based Data storage device initially intended for storage of up to 80 minutes of digitized audio For processes which reduce the amount of time it takes to listen to and understand a recording see Time-compressed speech.

Like most formats of videocassette, a DAT cassette may only be recorded on one side, unlike an analog compact audio cassette. Videotape is a means of recording images and sound onto Magnetic tape as opposed to movie film. The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply tape, is a Magnetic tape sound

History

Development

The technology of DAT is closely based on that of video recorders, using a rotating head and helical scan to record data. Helical scan is a method of recording high bandwidth signals onto Magnetic tape. This prevents DATs from being physically edited in the cut-and-splice manner of analog tapes, or open-reel digital tapes like ProDigi or DASH. Editing Language, Images or Sound through correction condensation organization and other modifications in various media Mitsubishi 's ProDigi is a Professional audio, Reel-to-reel, Digital audio tape format with a stationary head position similar to Sony The Digital Audio Stationary Head or DASH standard is a Reel-to-reel, Digital audio tape format introduced by Sony in early 1982 for

The DAT standard allows for four sampling modes: 32 kHz at 12 bits, and 32 kHz, 44. 1 kHz or 48 kHz at 16 bits. Certain recorders operate outside the specification, allowing recording at 96 kHz and 24 bits (HHS). Some machines aimed at the domestic market did not operate at 44. 1 kHz when recording from analog sources. Since each recording standard uses the same tape, the quality of the sampling has a direct relation to the duration of the recording – 32 kHz at 12 bits will allow six hours of recording onto a three hour tape while HHS will only give 90 minutes from a three hour tape. Included in the signal data are subcodes to indicate the start and end of tracks or to skip a section entirely; this allows for indexing and fast seeking. Two-channel stereo recording is supported under all sampling rates and bit depths, but the R-DAT standard does support 4-channel recording at 32 kHz. Stereophonic sound, commonly called stereo, is the reproduction of Sound, using two or more independent audio channels through a Symmetrical Sampling theorem The Nyquist–Shannon sampling theorem states that perfect reconstruction

DAT tapes are between 15 and 180 minutes in length, a 120-minute tape being 60 meters in length. DAT tapes longer than 60 meters tend to be problematic in DAT recorders due to the thinner media.

Predecessor formats

DAT was not the first digital audio tape; pulse-code modulation (PCM) was used in Japan to produce analogue phonograph records in the early 1970s, using a videotape recorder for its transport, but this was not developed into a consumer product. For a topic outline on this subject see List of basic Japan topics. A gramophone This article is about the Decade 1970-1979 For the Year 1970 see 1970. A transport is a device that handles a particular physical storage medium (such as Magnetic tape, Audio CD, CD-R, or other type of recordable media itself ( A consumer product is generally any tangible personal property for sale and that is used for personal family or household purposes

Later in 1976, the first commercially successful digital audio tape format was developed by Soundstream, using 1" (2. Soundstream Inc was founded in 1975 in Salt Lake City Utah by Dr 54 cm) wide reel-to-reel tape loaded on an instrumentation recorder manufactured by Honeywell acting as a transport, which in turn was connected to outboard digital audio encoding and decoding hardware of Soundstream's own design. Reel-to-reel, open reel tape recording is the form of magnetic tape audio recording in which the recording medium is held on a Reel, rather than being Instrumentation is the branch of science that deals with measurement and control in order to increase efficiency and safety in the workplace Honeywell ( is a major American multinational conglomerate company that produces a variety of consumer products engineering services and aerospace systems Several major record labels like RCA and Telarc used Soundstream's system to record some of the first commercially-released digital audio recordings. In the Music industry, a record label can be a Brand and a Trademark associated with the Marketing of music recordings and Music RCA Corporation, founded as Radio Corporation of America, was an electronics company in existence from 1919 to 1986 Telarc International Corporation is an Independent record label, based in Cleveland Ohio, United States, and founded in 1977 by two classically

Soon after Soundstream, 3M starting in 1978 introduced their own line (and format) of digital audio tape recorders for use in a recording studio, notably the model M79, with one of the first prototypes being installed in the studios of Sound 80 in Minneapolis, Minnesota. 3M Company ( formerly Minnesota Mining and Manufacturing Company until 2002 is an American multinational conglomerate corporation with a worldwide A recording studio is a facility for sound recording. Ideally the space is specially designed by an acoustician to achieve the desired acoustic properties (sound Sound 80 was a Recording studio in Minneapolis Minnesota, United States founded by Tom Jung and Herb Pilhofer in 1969.

Professional systems using a PCM adaptor, 98'7789 /'which digitized an analog audio signal and then encoded this resulting digital stream into an analog video signal so that a conventional VCR could be used as a storage medium, were also common as mastering formats starting in the late 1970s. A PCM adaptor is a device used for recording Digital audio in the PCM format which in turn connects to a Video cassette recorder (acting as a transport

dbx, Inc.'s Model 700 system, notable for using high sample-rate delta-sigma modulation (similar to modern Super Audio CDs) rather than PCM, and Decca's PCM system in the 1970s^[1] (using a videotape recorder manufactured by IVC for a transport), are two more examples. dbx Inc is a producer of professional audio recording equipment The dbx Model 700 Digital Audio Processor was a professional audio ADC / DAC combination unit which digitized a stereo analog audio input Super Audio CD ( SACD) is a read-only optical audio disc format that can provide higher fidelity digital audio reproduction than the Red International Video Corporation or IVC, was a company that manufactured several models of low to middle-end Videotape recorders, or VTRs for industrial and professional

Mitsubishi's X-80 digital recorder was another 6. The, Mitsubishi Group of Companies, or Mitsubishi Companies is a Japanese conglomerate consisting of a range of autonomous businesses which share the Mitsubishi 4 mm (¼") open reel digital mastering format that used a very unusual sampling rate of 50. Reel-to-reel, open reel tape recording is the form of magnetic tape audio recording in which the recording medium is held on a Reel, rather than being Mastering, a form of audio Post-production, is the process of preparing and transferring recorded audio from a source containing the final mix to a Data storage device 4 kHz.

For high-quality studio recording, effectively all of these formats were made obsolete in the early 1980s by two competing reel-to-reel formats with stationary heads: Sony's DASH format and Mitsubishi's continuation of the X-80 recorder, which was improved upon to become the ProDigi format. Reel-to-reel, open reel tape recording is the form of magnetic tape audio recording in which the recording medium is held on a Reel, rather than being is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with The Digital Audio Stationary Head or DASH standard is a Reel-to-reel, Digital audio tape format introduced by Sony in early 1982 for The, Mitsubishi Group of Companies, or Mitsubishi Companies is a Japanese conglomerate consisting of a range of autonomous businesses which share the Mitsubishi Mitsubishi 's ProDigi is a Professional audio, Reel-to-reel, Digital audio tape format with a stationary head position similar to Sony (In fact, the first ProDigi-format recorder, the Mitsubishi X-86, was playback-compatible with tapes recorded on an X-80. ) Both of these formats remained popular as an analog alternative until the early 1990s, when hard disk recorders rendered them obsolete.

Anti-DAT lobbying

In the late 1980s, the Recording Industry Association of America unsuccessfully lobbied against the introduction of DAT devices into the U. S. Initially, the organization threatened legal action against any manufacturer attempting to sell DAT machines in the country. It later sought to impose restrictions on DAT recorders to prevent them from being used to copy LPs, CDs, and prerecorded cassettes. This opposition was led by CBS Records president Walter Yetnikoff, but softened after Sony, a DAT manufacturer, bought CBS Records in January 1988. Walter Yetnikoff (Born 11 August 1933 Brooklyn New York is a former CBS Records/Sony Music executive famed for his flamboyant business style and for his penchant for living By June 1989, an agreement was reached, and the only concession the RIAA would receive was a more practical recommendation from manufacturers to Congress that legislation be enacted to require that recorders have a Serial Copy Management System to prevent digital copying for more than a single generation. The Serial Copy Management System or SCMS was created in response to the Digital audio tape (DAT invention in order to prevent DAT recorders from making second-generation ^[2] This requirement was enacted as part of the Audio Home Recording Act of 1992.

Uses of DAT

Professional recording industry

DAT was widely used in the professional audio recording industry in the 1990s, and is still used to some extent today, as the archives created in the '90s are still widely used, although most labels have a program in place to transfer these tapes to a computer-based database. DAT was used professionally due to its lossless encoding, which allowed a master tape to be created that was more secure and did not induce yet more tape noise (hiss) onto the recording. In the correct setup, a DAT recording could be created without even having to be decoded to analogue until the final output stage, since digital multi-track recorders and digital mixing consoles could be used to create a fully digital chain. In this configuration, it is possible for the audio to remain digital from the first AD converter after the mic preamp until it is in a CD player.

DAT's were also frequently used by radio broadcasters. Until recently, they were still used by the BBC as an emergency broadcast that would initiate if the player detected a lack of noise continued for more than a pre-determined time. This would mean that if for any reason the broadcast from the studio stopped, the DAT would continue broadcast until normal service could be resumed.

Amateur and home use

DAT was envisaged by proponents as the successor format to analogue audio cassettes in the way that the compact disc was the successor to vinyl-based recordings; however, the technology was never as commercially popular as CD. DAT recorders remained relatively expensive, and commercial recordings were generally not made available on the format. However, DAT was, for a time, popular for making and trading recordings of live music, since available DAT recorders predated affordable CD recorders.

In the U. S. , the RIAA and music publishers continued to lobby against DAT, arguing that consumers' ability to make perfect digital copies of music would destroy the market for commercial audio recordings. The opposition to DAT culminated in the passage of the resulting Audio Home Recording Act of 1992, which, among other things, effectively imposed a tax on DAT devices and blank media.

Computer data storage medium

The format was designed for audio use, but through the ISO Digital Data Storage standard it has been adopted for general data storage, storing from 1. Digital Data Storage ( DDS) is a format for storing and backing up Computer Data on Magnetic tape that evolved from Digital Audio 3 to 72 GB on a 60 to 170 meter tape depending on the standard and compression. It is sequential-access media and is commonly used for backups. In Information technology, backup refers to making copies of Data so that these additional copies may be used to restore the original after a Due to the higher requirements for capacity and integrity in data backups, a computer-grade DAT was introduced, called DDS (Digital Data Storage). Although functionally similar to audio DATs, only a few DDS and DAT drives (in particular, those manufactured by Archive for SGI workstations^[3]) are capable of reading the audio data from a DAT cassette. SGI DDS4 drives no longer have audio support; SGI removed the feature due to "lack of demand"^[4].

Future of DAT

In November 2005, Sony announced that the final DAT machines would be discontinued the following month. [1] However, the DAT format still finds regular use in film and television recording, principally due to the support in some recorders for SMPTE time code synchronization, although it is slowly being superseded by modern hard disk recording equipment which offers much more flexibility and storage. Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic SMPTE timecode is a set of cooperating standards to label individual frames of video or film with a Timecode defined by the Society of Motion Picture and Television Engineers A hard disk drive ( HDD) commonly referred to as a hard drive, hard disk, or fixed disk drive, is a Non-volatile storage device In 2004, Sony introduced the Hi-MD Walkman with the ability to record in linear PCM. In January 2004 Sony announced the Hi-MD media storage format as a further development of the MiniDisc-Format. Hi-MD has found some favour as a disc-based DAT alternative for field recordings and general portable playback.

Archived audio problem

The discontinuation of DAT replayer production leads to a significant problem regarding audio archives, since a tremendous amount of recordings from the mid-80's until about 2000 exist solely on DATs. This means that this material is locked up on these tapes.

Even if some larger broadcasting facilities or studios still have some DAT recorder/players in their internal stock or could find a handful of second hand models, each unit can inevitably suffer from wear-out in the spining drum heads, winding mechanisms, brakes, etc. The best solution would be to trasfer the information off the DAT tapes and into computer-based hard drive systems via an AES/EBU digital connection. Even though these "transfers" have to happen in real-time which can make this process tedious and time consuming, an exact clone can be made using this process, whereas no digital information will be lossed or compromised. Running the DAT through an analouge soundboard and then into the hard drive system, would forever defeat this purpose.

See also

• ADAT
• Magnetic Tape
• PCM adaptor
• Digital Audio Stationary Head
• ProDigi

Audio/video

• Digital Compact Cassette (DCC)
• Compact Disc (CD)
• MiniDisc (MD)
• Digital Versatile Disc (DVD)
• Universal Media Disc (UMD)
• Super Audio CD (SACD)

References