System and method for enabling compatibility between digital and analog television systems

• US 7,099,388 B2
• Filed: 08/10/2001
• Issued: 08/29/2006
• Est. Priority Date: 08/25/2000
• Status: Expired due to Fees

• Current Assignee: Cascades AV LLC (Cascades Ventures, Inc.)
• Original Assignee: J. Carl Cooper
• Inventors: Cooper, J. Carl
• Primary Examiner(s): PHILIPPE, GIMS S
• Application Number:
  US09/927,743
• Publication Number:
  US 20020024998A1
• Time in Patent Office: 1,845 Days
• Field of Search: 375/240.01, 375/240.28, 348/569, 348/441, 348/458, 348/723, 348/445
• US Class Current: 375/240.01
• CPC Class Codes: H04N 7/01 Conversion of standards , e.g. involving analogue television standards or digital television standards processed at pixel level
• CPC Class Codes: H04N 7/0125 one of the standards being a high definition standard
• CPC Class Codes: H04N 7/025 Systems for the transmission of digital non-picture data, e.g. of text during the active part of a television frame transmission of digital non-picture data during the vertical blanking interval only H04N7/088

Abstract

The invention converts a digital HDTV or SDTV video and/or audio signal(s) into an analog signal which is compatible with existing analog systems. The compatible analog signal carries the digital video and/or audio in a quasi digital form which provides immunity to analog noise and distortion. Digital video and audio are compressed to provide digital compressed signals that are coupled to a digital to analog formatter where they are formatted into an NTSC, PAL, or SECAM compatible analog signal. The active video portion of the signal uses a multilevel pulse amplitude coded signal to carry the digital compressed signal. The converted analog signal can then be stored or transmitted using existing NTSC, PAL, or SECAM standards and equipment.

Claims

1. A method of creating a compatible analog signal which carries a digital video signal on an existing analog video system including the steps of:

a video compression step responsive to said digital video signal to provide a compressed video signal; and

a digital to analog formatter step responsive to said compressed video signal and providing said compatible analog signal carrying said compressed video signal as a quasidigital signal, which compatible analog signal may be utilized by said analog video system.

13. The method as claimed in claim 1, 2 or 3 wherein said compatible analog signal includes horizontal sync pulses with the amplitude of said compatible analog signal being restricted to discrete values at specific times, each of which specific times is caused to occur at a known time after the preceding horizontal sync pulse.

14. The method as claimed in claim 1, 2 or 3 wherein said compatible analog signal is constrained to discrete amplitude values at specific times, and is further constrained such that the rise and fall times of transitions of said compatible analog signal between said discrete amplitude values is limited.

15. The method as claimed in claim 1, 2 or 3 wherein said compatible analog signal is constrained to discrete amplitude values at specific times, and is further constrained such that the rise and fall times of transitions of said compatible analog signal between said discrete amplitude values is shaped and limited.

2. A method of creating one of an NTSC or PAL or SECAM compatible analog signal which carries a digital HDTV video signal on an existing analog video system including the steps of:

a video compression step responsive to said digital HDTV video signal to provide a compressed video signal; and

a digital to analog formatter step responsive to said compressed video signal and providing said NTSC or PAL or SECAM compatible analog signal which includes a quasidigital signal which compatible analog signal may be utilized by said analog video system.

3. A method of creating one of an NTSC, or PAL or SECAM compatible analog signal which carries a digital HDTV program audio and video signal on an existing analog video system including the steps of:

a video compression step responsive to said digital HDTV audio and video signals to provide a compressed audio and video signal; and

a digital to analog formatter step responsive to said compressed audio and video signal and providing said NTSC or PAL or SECAM compatible analog signal that includes said compressed audio and video signal as a quasidigital signal, which compatible analog signal may be utilized by said analog video system.

4. A method of carrying digital information as an analog signal which includes synchronizing information according to a standard, said method including the steps of:

compressing said digital information;

encoding said compressed digital information as a quasidigital signal;

selecting ones of said synchronizing information necessary for a signal to be compatible with said standard;

combining said quasidigital signal and said selected ones of said synchronizing information to produce said analog signal.

5. The method as in claim 4 wherein said analog signal is a television video signal having horizontal and vertical synchronizing pulses.

6. The method as in claim 4 wherein said analog signal is a television video signal having horizontal and vertical synchronizing pulses and color burst.

7. The method as in claim 4 wherein said quasidigital signal carries digitized video.

8. The method as in claim 4 wherein said quasidigital signal carries digitized audio.

9. The method as in claim 4 wherein said quasidigital signal carries digitized audio and digitized video.

10. The method as in claim 4 wherein said quasidigital signal carries digitized video in MPEG form.

11. The method as in claim 4 wherein said quasidigital signal carries digitized audio in MPEG form.

12. The method as in claim 4 wherein said quasidigital signal carries digitized audio and digitized video in MPEG form.

16. A method of receiving a digital signal carried in analog form wherein the analog form is restricted to discrete values at specific times, including the steps of:

a) identifying said specific times,

b) identifying which of said discrete values said analog form is closest to at each of said specific times,

c) in response to step b), providing the digital value corresponding to said identified discrete value,

d) in response to each digital value of step c) providing said digital signal.

19. The method as claimed in claim 16, 17 or 18 wherein said digital signal is a television program consisting of audio and video portions and said analog form is one of an analog SDTV or HDTV type signal.

20. The method as claimed in claim 16, 17 or 18 wherein said digital signal is the video portion of a television program and said analog form is one of an analog SDTV or HDTV type signal.

21. The method as claimed in claim 16, 17 or 18 wherein said digital signal is an AES/EBU audio portion of a television program and said analog form is one of an analog SDTV or HDTV type signal.

22. The method as claimed in claim 16, 17 or 18 wherein in step d) error detection and correction is applied to said digital signal.

23. The method as claimed in claim 16, 17 or 18 wherein said specific times have uniform time durations.

24. The method as claimed in claim 16, 17 or 18 wherein said discrete values have uniform amplitude separation.

25. The method as claimed in claim 16, 17 or 18 wherein said specific times have non-uniform time durations.

26. The method as claimed in claim 16, 17 or 18 wherein said discrete values have non-uniform amplitude separation.

17. A method of receiving a digital signal which is compressed and carried in analog form wherein the analog form is restricted to discrete values at specific times, including the steps of:

a) identifying said specific times,

b) identifying which of said discrete values said analog form is closest to at each of said specific times,

c) in response to step b), providing the digital value corresponding to said identified discrete value,

d) in response to each digital value of step c) decompressing and providing said digital signal.

18. A method of receiving a digital signal carried in analog form wherein the analog form is restricted to discrete values at specific times, which specific times are related to a synchronizing event occurring in said analog form, including the steps of:

a) identifying each of said specific times in response to said synchronizing event,

b) identifying which of said discrete values said analog form is closest to at each of said specific times,

c) in response to step b), providing the digital value corresponding to said identified discrete value,

d) in response to each digital value of step c) providing said digital signal.