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

A method for reading audio information and data related to the audio information from the same track of a magnetic tape comprising the steps of:

• positioning a read head in close proximity to the track of the magnetic tape to detect changes in the magnetization of the track of the magnetic tape;
• generating an electrical signal in response to the detected changes;
• filtering the generated electrical signal to remove frequencies outside of the frequency range of human hearing to form an audio signal containing the audio information that is suitable for playing without having to be demodulated;
• filtering the generated electrical signal to recover a carrier signal on which digital data is modulated, the carrier signal being at a frequency near the peak of a side lobe of the frequency response curve of the read head and outside the frequency range of human hearing;
• and
• demodulating the carrier signal to form a data signal containing the information related to the audio signal.

A method for recording audio information and data related to the audio information on the same track of a magnetic recording tape so that the magnetic recording tape may be interchangeably played in either a tape player that reads only audio information without interference from the data or a tape player that can read both the audio information and the data, the method comprising the steps of:

• generating a signal containing the audio information;
• generating data that is related to the audio information;
• generating an ultrasonic carrier signal having a frequency near the peak of a sidelobe in the frequency response curve of the recording head and outside the frequency range of human hearing;
• modulating the ultrasonic carrier signal with the data related to the information in the audio signal;
• combining the audio signal and the modulated ultrasonic signal to form a composite signal;
• applying the composite signal to a recording head positioned above the track of the magnetic tape to create a changing magnetic field in response to the composite signal;
• and
• magnetizing the track of the magnetic tape in response to the changing magnetic field to record the composite signal thereon.

A method for reading audio information and modulated data related to the audio information from the same track of a magnetic tape comprising the steps of:

• detecting changes in the magnetization of the track of the magnetic tape by the use of a read head;
• generating an electrical signal in response to the detected changes;
• dividing the generated electrical signal into first and second divided signals;
• filtering the first divided signal to remove frequencies outside of the frequency range of human hearing to form an audio signal containing the audio information;
• filtering the second divided signal to remove frequency components below a predetermined frequency to form a high pass filtered signal;
• and
• frequency demodulating the high pass filtered signal from an ultrasonic carrier signal having a frequency near the peak of a sidelobe of the frequency response curve of the read head and outside the frequency range of human hearing in order to form a data signal containing the information related to the audio signal.