Method and apparatus for reading and writing audio and digital data on a magnetic tape

摘要

A method and apparatus for recording and reading magnetic tape that contains audio signals and data that is related to the audio signals. In the preferred embodiment, the audio signals are music, and the related data are lyrics to the music displayed in real time to the music as it is being played. The lyrics are modulated onto an ultrasonic carrier signal and mixed with the audio signal on one track of the tape. The tape may be played on a conventional tape recorder without having interference from the recorded data at ultrasonic frequencies. In a suitably equipped tape player, the mixed signal is read and filtered to generate a high pass filtered signal and a bandpass filtered signal. The bandpass filtered signal filters out frequencies outside the range of human hearing to generate an audio signal. The high pass filtered signal is demodulated by the carrier frequency to reconstruct the lyrics. A two-track system records an unmodulated carrier frequency on the second track and is subtracted from the modulated carrier frequency to generate the lyrics. This compensates for variations in tape speed that shift the frequency of the data modulated carrier signal.