Recording and playback on magnetic tape: the process of converting sound signals into corresponding changing magnetic fields and recording them on magnetic tape in the form of remanence is called magnetic recording. Its principle is based on the phenomenon that hard magnetic materials still have remanence after magnetization, and a hard magnetic material can be magnetized in sections. The magnetic medium on which the sound signal is recorded passes through the annular playback head with a gap at the same speed as the recording. The magnetic flux recorded on the medium will induce the electromotive force corresponding to the signal in the head coil, and then reproduce the original sound after amplification. Recorders are mainly divided into disc type and cassette type. Magnetic tape is a kind of tape storage system, and it is one of the commonly used storage media with the lowest cost, the largest capacity and the highest standardization. It has good interchangeability and easy storage. In recent years, due to the adoption of coding technology with strong error correction ability and channel technology with strong reading and writing ability, the reliability and reading and writing speed of tape storage have been greatly improved.
According to the working principle of reading and writing magnetic tape, it can be divided into spiral scanning technology, linear recording (data stream) technology, DLT technology and more advanced LTO technology. Spiral scanning reading and writing technology: A tape reading and writing technology that reads and writes data on a tape through spiral scanning, which is basically similar to a video recorder. The magnetic tape is wound on most magnetic drums and moves horizontally at low speed, while the magnetic drum rotates reversely at high speed during the tape reading and writing process, and the magnetic head installed on the surface of the magnetic drum completes data access and reading during the rotation process. Its head keeps an inclination of 15 degrees with the tape when reading and writing, and the tracks are arranged in parallel with an inclination of 75 degrees on the tape. Using this read-write technology, more data channels can be obtained in the same tape area, which makes full use of the effective storage space of the tape, so it has higher data access density.