The periodic longitudinal vibration of a video and audio tape and the like used for transducing pictures and sounds can be induced by the self-excited vibrations, caused by friction against the heads and guides, and its eccentricity, noncircularity or irregularity. It is important to analyze the longitudinal vibration of a tape because it can cause distortion of a reproduced signal.
The method estimating longitudinal vibration using impulse response in the transverse direction is presented for the difficuity of sensing the longitudinal vibration directly. And, the parameters' boundary domain where the transverse and longitudinal vibration can be decoupled is introduced. In this decoupled domain of mutual vibrations, analytic method using frequency characteristics and transient response of the transverse vibration is presented. The time domain method has more advantages in that it can predict more exectly the instantaneous phase of the longitudinal vibration than frequency domain method.
