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

• US 5,619,383 A
• Filed: 05/05/1995
• Issued: 04/08/1997
• Est. Priority Date: 05/26/1993
• Status: Expired due to Fees

• Current Assignee: Rovi Guides, Inc. (Adeia Inc.)
• Original Assignee: Gemstar Development Corporation (Adeia Inc.)
• Inventors: Ngai, Hing Y.
• Primary Examiner(s): Sniezek, Andrew L.
• Application Number:
  US08/441,392
• Time in Patent Office: 704 Days
• Field of Search: 360/20, 360/29, 360/30, 360/19.1, 360/18, 84/642, 84/645, 395/2, 395/2.39
• US Class Current: 360/20
• CPC Class Codes: G10H 1/0033 Recording/reproducing or transmission of music for electrophonic musical instruments
• CPC Class Codes: G10H 1/361 Recording/reproducing of accompaniment for use with an external source, e.g. karaoke systems
• CPC Class Codes: G10H 2220/011 Lyrics displays, e.g. for karaoke applications
• CPC Class Codes: G10H 2250/031 Spectrum envelope processing
• CPC Class Codes: G11B 20/00992 Circuits for stereophonic or quadraphonic recording or reproducing
• CPC Class Codes: G11B 20/06 Angle-modulation recording or reproducing
• CPC Class Codes: G11B 20/225 for reducing wow or flutter by controlling the speed of the record carrier G11B15/46, G11B19/28
• CPC Class Codes: G11B 27/107 of operating tapes
• CPC Class Codes: G11B 5/00813 magnetic tapes
• CPC Class Codes: G11B 5/02 Recording, reproducing, or erasing methods; Read, write or erase circuits therefor

Abstract

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.

Claims

1. 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:

positioning a recording head near the track of the magnetic tape;

generating an unmodulated audio signal containing the audio information;

generating digital data that is related to the audio information;

generating a carrier signal at a frequency near the peak of a side lobe in the frequency response curve of the recording head and outside the frequency range of human hearing;

modulating the carrier signal with the data related to the information in the audio signal;

combining the audio signal and the modulated signal to form a composite signal;

applying the composite signal to the recording head 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.

2. The method of claim 1 wherein the carrier frequency is approximately 33 KHz.

3. The method of claim 1 wherein the step of modulating the ultrasonic carrier signal includes the step of frequency modulating the ultrasonic carrier signal.

4. The method of claim 1 wherein the audio information is music and the data related to the audio information is lyrics to the music.

5. 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.

6. The method of claim 5 wherein the audio information is music and the data related to the audio information is lyrics to the music.

7. The method of claim 6 further comprising the steps of playing the music and displaying the lyrics to the music in synchronization with the music being played.

8. The method of claim 5 wherein the carrier frequency is approximately 33 KHz.

9. The method of claim 8 wherein the modulated data is digital data frequency modulated onto the carrier signal so that a first logic state is at 32 KHz and a second logic state is at 34 KHz.

10. 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.

11. The method of claim 10 wherein the carrier frequency is approximately 33 Khz.

12. 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.

13. The method of claim 12 wherein the carrier frequency is approximately 33 KHz.

14. The method of claim 13 wherein the modulated data is digital data frequency modulated onto the carrier signal so that a first logic state is at 32 KHz and a second logic state is at 34 KHZ.