Signal Track

an information carrier in the form of, for example, a tape, disk, or sheet together with the signals recorded on the carrier. On the signal track there is a recording track, which is the trace left by the recording device on the moving carrier during the recording process. The recording track may consist, for example, of a groove in the carrier, of a trace of a pigment on the surface of the carrier, or of magnetized or electrified regions of the carrier. Various shapes of recording tracks are used; the tracks may be rectilinear or spiral or may consist of a series of segments, as in line-by-line recording.

A signal track on which several recording tracks are recorded simultaneously or consecutively is said to be multitrack. Special cases of a signal track are a sound track (in sound recording), a video track (in recording image signals), and a video sound track (in recording both images and sound). The name of a signal track often includes an indication of the recording system used. Thus, a phonograph record is called a mechanical sound track, a magnetic tape with recorded sound signals is called a magnetic sound track, and a motion-picture film with recorded sound signals is called an optical sound track. Sometimes the name of a signal track indicates the purpose or characteristics of the recorded information—for example, a telemetric signal track or a stereophonic sound track. During the reproduction of the recorded information the recording track of the moving signal track interacts with the corresponding component of the reproduction device. (More detailed information is given in RECORDING AND REPRODUCTION OF INFORMATION.)