Method and apparatus for creating encrypted and decrypted television signals

• US 4,642,688 A
• Filed: 05/21/1985
• Issued: 02/10/1987
• Est. Priority Date: 06/24/1983
• Status: Expired due to Term

• Current Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Lucas, Keith, Lowry, John D.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/736,301
• Time in Patent Office: 630 Days
• Field of Search: 358/120, 358/123, 358/12, 358/114, 358/119
• US Class Current: 380/218
• CPC Class Codes: H04N 7/1696 by changing or reversing the order of active picture signal portions

Abstract

A method and apparatus for creating a television signal and encrypting or decrypting the signal at the same time. Luminance and chrominance information are received by the apparatus and stored in separate television scan line stores. The stored liminance and chrominance information is read out from their respective stores at a frequency corresponding to a desired format or standard to create the television signal. The signal may be simultaneously encrypted or decrypted by delaying the time at which the luminance and/or chrominance information is read out in accordance with an encryption or decryption key.

Claims

1. An apparatus for creating a MAC standard television signal and for encrypting said MAC signal at the time of its creation, said apparatus comprising:

input means for receiving a scan line of luminance information, a scan line of color difference information and an encryption key;

luminance storage means coupled to said input means for storing a scan line of said luminance information and subsequently reading out said stored line of luminance information to create said MAC standard signal, said luminance storage means including first and second memory means; and

first and second clock signal means coupled to respective said first and second memory means, said first clock signal means being arranged to cause said first memory means to store a present scan line of said luminance information when said second clock signal means causes said second memory means to read out said stored scan line of luminance information, said second clock signal means being arranged to cause said second memory means to store a present scan line of said luminance information when said first clock signal means causes said first memory means to read out said stored scan line of luminance information, wherein said first and second clock signal means causes said first and second memory means to delay reading out said stored scan line of luminance information in accordance with said encryption key, said first and second clock signal means causes said respective first and second memory means to store a predetermined number of samples of said luminance information at a first predetermined sampling frequency and to read out sid stored scan line of luminance information at a second predetermined sampling frequency.

2. The apparatus of claim 1 wherein said predetermined number of samples is 750, said first predetermined sampling frequency is 14.32 MHz and said second predetermined sampling frequency is 21.48 MHz.

3. The apparatus of claim 1 wherein said first and second memory means comprises RAM memory.

4. The apparatus of claim 1 wherein said first and second memory means comprises a plurality of shift registers.

5. The apparatus of claim 1 wherein said first and second memory means comprises a plurality of CCD elements.

6. The apparatus of claim 1 further comprising color storage means coupled to said input means for storing a scan line of said color difference information and subsequently reading out said stored scan line of color difference information to create said MAC standard signal.

7. The apparatus of claim 6 wherein said color storage means includes first and second memory means coupled to said first and second clock signal means respectively, said first clock signal means being arranged to cause said first memory means of said color storage means to store a present scan line of said color difference information when said second clock signal means causes said second memory means of said color storage means to read out said stored scan line of color difference information, said second clock signal means being arranged to cause said second memory means of said color storage means to store a present scan line of said color difference information when said first clock signal means causes said first memory means of said color storage means to read out said stored scan line of color difference information, wherein said first and second clock signal means causes said first and second memory means of said color storage means to delay reading out said stored scan line of color difference information in accordance with said encryption key.

8. The apparatus of claim 7 wherein said first and second clock signal means causes said respective first and second memory means of said color storage means to store a predetermined number of samples of said color difference information at a first predetermined sampling frequency and to read out said stored scan line of color difference information at a second predetermined sampling frequency.

9. The apparatus of claim 8 wherein said predetermined number of samples is 750, said first predetermined sampling frequency is 14.32 MHz and said second predetermined sampling frequency is 21.48 MHz.

10. An apparatus for creating an NTSC standard television signal and for decrypting said NTSC signal at the time of its creation, said apparatus comprising:

input means for receiving a scan line of luminance information, a scan line of color difference information and a decryption key;

luminance storage means coupled to said input means for storing a scan line of said luminance information and subsequently reading out said stored scan line of luminance information to create said NTSC standard signal, said luminance storage means including first and second memory means; and

first and second clock signal means coupled to respective said first and second memory means, said first clock signal means being arranged to cause said first memory means to store a present scan line of said luminance information when said second clock signal means causes said second memory means to read out said stored scan line of luminance information, said second clock signal means being arranged to cause said second memory means to store a present scan line of said luminance information when said first clock signal means causes said first memory means to read out said stored scan line of luminance information, wherein said first and second clock signal means causes said first and second memory means to delay reading out said stored scan line of luminance information in accordance with said decryption key, wherein said first and second clock signal means causes said respective first and second memory means to store a predetermined number of samples of said luminance information at a first predetermined sampling frequency and to read out said stored scan line luminance information at a second predetermined sampling frequency.

11. The apparatus of claim 10 wherein said predetermined number of samples is 750, said first predetermined sampling frequency is 21.48 MHz and said second predetermined sampling frequency is 14.32 MHz.

12. The apparatus of claim 10 wherein said first and second memory means comprises RAM memory.

13. The apparatus of claim 10 wherein said first and second memory means comprises a plurality of shift registers.

14. The apparatus of claim 10 wherein said first and second memory means comprises a plurality of CCD elements.

15. The apparatus of claim 10 further comprising color storage means coupled to said input means for storing a scan line of said color difference information and subsequently reading out said stored scan line of color difference information to create said NTSC standard signal.

16. The apparatus of claim 15 wherein said color storage means includes first and second memory means coupled to said first and second clock signal means respectively, said first clock signal means being arranged to cause said first memory means of said color storage means to store a present scan line of said color difference information when said second clock signal means causes said second memory means of said color storage means to read out said stored scan line of color difference information, said second clock signal means being arranged to cause said second memory means of said color storage means to store a present scan line of said color difference information when said first clock signal mean causes said first memory means of said color storage means to read out said stored scan line of color difference information, wherein said first and second clock signal means causes said first and second memory means of said color storage means to delay reading out said stored scan line of color difference information in accordance with said decryption key.

17. The apparatus of claim 16 wherein said first and second clock signal means causes said respective first and second memory means of said color storage means to store a predetermined number of samples frequency and to read out said stored scan line of color difference information at a second predetermined sampling frequency.

18. The apparatus of claim 17 wherein said predetermined number of samples is 750, said first predetermined sampling frequency is 21.48 MHz and said second sampling predetermined frequency is 14.32 MHz.

19. A method of simultaneously creating a MAC standard television signal by compressing luminance or color difference information and encrypting said MAC standard signal comprising the steps of:

storing a predetermined number of samples of a scan line of luminance information in one line store at a first predetermined sampling frequency; and

commencing reading out said stored scan line of luminance information from said one line store at a second predetermined sampling frequency after a time delay determined by an encryption key.

20. The method of claim 19 wherein said predetermined number of samples is 750, said first predetermined sampling frequency is 14.32 MHz, and said second predetermined sampling frequency is 21.48 MHz.

21. The method of claim 19 further comprising the steps of:

storing a predetermined number of samples of a scan line of color difference information in a separate line store at said first predetermined sampling frequency; and

commencing reading out said stored scan line of color difference information from said separate line store at said second predetermined sampling frequency after a time delay determined by said encryption key.

22. A method of simultaneously creating a decrypted NTSC standard television signal from an encrypted MAC signal by decompressing luminance or color difference information comprising the steps of:

storing a predetermined number of samples of a scan line of luminance information in one line store at a first predetermined sampling frequency; and

commencing reading out said stored scan line of luminance information from said one line store at a second predetermined sampling frequency after a time delay determined by a decryption key.

23. The method of claim 22 wherein said predetermined number of samples is 750, said first predetermined sampling frequency is 21.48 MHz, and said second predetermined sampling frequency is 14.32 MHz.

24. The method of claim 22 further comprising the steps of:

storing a predetermined number of samples of a scan line of color difference information in a separate line store at said first predetermined sampling frequency; and

commencing reading out said stored scan line of color difference information from said separate line store at said second predetermined sampling frequency after a time delay determined by said decryption key.