Sony NT: Цифрлық жазба жүйесі

Audio cassette format developed by Sony

NT (sometimes marketed under the name Scoopman) is a digital memo recording system introduced by Sony in 1992. The NT system was introduced to compete with the Microcassette, introduced by Olympus, and the Mini Cassette, by Philips.

The system was an R DAT based system which stored memos using helical scan on special microcassettes, which were 30 mm × 21.5 mm × 5 mm with a tape width of 2.5 mm, with a recording capacity of up to 120 minutes similar to Digital Audio Tape. The cassettes are offered in three versions: The Sony NTC 60, 90, and 120, each describing the length of time (in minutes) the cassette can record. NT stands for Non Tracking, meaning the head does not precisely follow the tracks on the tape. Instead, the head moves over the tape at approximately the correct angle and speed, but performs more than one pass over each track. The data in each track is stored on the tape in blocks with addressing information that enables reconstruction in memory from several passes. This considerably reduced the required mechanical precision, reducing the complexity, size, and cost of the recorder. Another feature of NT cassettes is Non Loading, which means instead of having a mechanism to pull the tape out of the cassette and wrap it around the drum, the drum is pushed inside the cassette to achieve the same effect. This also significantly reduces the complexity, size, and cost of the mechanism. Audio sampling is in stereo at 32 kHz with 12 bit nonlinear quantization, corresponding to 17 bit linear quantization. Data written to the tape is packed into data blocks and encoded with LDM 2 low deviation modulation.

The Sony NT 1 Digital Micro Recorder, introduced in 1992, features a real time clock that records a time signal on the digital track along with the sound data, making it useful for journalism, police and legal work. Due to the machine's buffer memory, it is capable of automatically reversing the tape direction at the end of the reel without an interruption in the sound. Rebranded NT cassettes were used as the storage medium in the Datasonix Pereos backup system from 1994, claiming a capacity of up to 1.25 gigabytes per tape. Due to overhead and variable data compression ratios, the actual amount of data stored could be significantly below a gigabyte.