Timing control for injecting a burst and data into a video signal

• US 5,410,360 A
• Filed: 06/14/1993
• Issued: 04/25/1995
• Est. Priority Date: 06/14/1991
• Status: Expired due to Fees

• Current Assignee: WAVO Corporation
• Original Assignee: WavePhore, Inc.
• Inventors: Montgomery, Gerald D.
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Metjahic, Safet
• Application Number:
  US08/076,137
• Time in Patent Office: 680 Days
• Field of Search: 358/142, 358/141, 358/12, 358/13, 358/19, 358/15, 358/148, 358/149, 358/150, 348/486, 348/475, 348/474, 348/473, 348/476, 348/471, 348/472, 348/470, 348/469, 348/436, 348/434, 348/433, 348/432, 348/426, 348/461, 348/465, 348/467, 348/464, 348/460 , 348/495, 348/496, 348/505, 348/506, 348/507, 348/385, 348/386, 348/536, 348/537, 348/500, 348/508, 348/512, 348/520
• US Class Current: 348/473
• CPC Class Codes: H04N 1/00098 via a television channel, e.g. for a series of still pictures with or without sound
• CPC Class Codes: H04N 5/445 for displaying additional information H04N5/50 takes precedence
• CPC Class Codes: H04N 7/0803 using frequency interleaving, e.g. with precision offset
• CPC Class Codes: H04N 7/081 the additional information signals being transmitted by means of a subcarrier
• CPC Class Codes: H04N 7/10 Adaptations for transmission by electrical cable H04N7/12 takes precedence

Abstract

A secondary signal is processed and injected into a primary color video signal. The timing of the subsequent transmission of the secondary signal is controlled by timing signals. The timing signals also control the transmission of a carrier burst prior to the transmission of the secondary data signal. This carrier burst is used by a receiver to synchronize with the transmitter, reduce transmission errors and to indicate that a data transmission is to follow.

Claims

1. A processor for combining a primary color video signal having active video lines separated by blanking intervals, and having a color burst with a secondary signal for subsequent transmission, the processor comprising:

a primary signal section providing the primary color video signal having active intervals and blanking intervals;

a secondary signal section generating a secondary signal carrier at a frequency of a predetermined number of cycles per second for providing a carrier burst and being modulated by a rasterized version of the secondary signal for injecting into the primary color video signal; and

a timing section for generating at least one timing signal to control the injection of the carrier burst into the primary color video signal for a predetermined time period such that the injection of the burst and the rasterized data is halted a predetermined period before each blanking interval.

2. A processor according to claim 1, wherein the primary color video signal blanking intervals include horizontal blanking intervals, and wherein the carrier burst is injected into the primary color video signal immediately after at least some horizontal blanking intervals.

3. A processor according to claim 1, wherein the horizontal blanking interval has a front porch and a back porch, and wherein the carrier burst is injected into the primary color video signal during one of the front porch and the back porch.

4. A processor according to claim 2, wherein each horizontal blanking interval has a back porch having an end during which a color burst is generated, and wherein the carrier burst is injected into the primary color video signal after the color burst and before the end of the back porch.

5. A processor according to claim 1, wherein at least one timing signal controls the carrier burst to last for a predetermined number of the secondary signal carrier cycles.

6. A processor according to claim 5, wherein the active video lines each have an end, and wherein the secondary signal is injected into the primary color video signal until the end is a predetermined number of cycles of the secondary signal carrier away.

7. A processor according to claim 6, wherein the primary color video signal conforms to an NTSC standard.

8. A processor according to claim 6, wherein the primary color video signal conforms to a PAL standard.

9. A processor according to claim 6, wherein the primary color video signal conforms to a SECAM standard.

10. A processor according to claim 1, wherein the primary color video signal has a horizontal scanning frequency, and wherein the secondary signal is injected into the primary color video signal at a non-integral, odd quarter multiple of the horizontal scanning frequency.

11. A method of combining a primary color video signal with a secondary signal for subsequent transmission, the method comprising the steps of:

providing a primary color video signal having active video lines separated by blanking intervals;

generating a secondary signal carrier having a frequency with a predetermined number of cycles per second and a secondary signal carrier burst;

producing at least one timing signal based upon at least some of the blanking intervals in the video signal;

injecting in response to the timing signal the carrier burst of the secondary signal carrier for subsequent transmission into the active video lines;

modulating and rasterizing the secondary signal with the secondary signal carrier for injection into the primary video signal; and

injecting the secondary signal only during the active video lines when the carrier burst is not being injected into the primary video signal to form a composite signal for subsequent transmission after subsequent transmission of the carrier burst.

12. A method according to claim 11, further comprising:

providing the primary color video signal with a horizontal blanking period as one of the blanking intervals; and

injecting the carrier burst into the primary color video signal after at least some of the horizontal blanking intervals.

13. A method according to claim 11, further comprising:

providing the horizontal blanking period with a back porch;

generating a color burst during the back porch; and

injecting the carrier burst into the primary color video signal immediately after the back porch.

14. A method according to claim 13, further comprising:

injecting the carrier burst into the primary color video signal for at least five cycles of the secondary signal carrier.

15. A method according to claim 12, wherein the primary color video signal has active video lines with ends;

and

injecting the secondary signal into the primary color video signal until a predetermined period prior to the end of the active lines of the primary color video signal.

16. A method according to claim 15, wherein the primary color video signal is according to an NTSC standard.

17. A method according to claim 11, further comprising:

providing the primary color video signal with a horizontal scanning frequency; and

injecting the secondary signal into the primary color video signal at a non-integral, odd quarter multiple of the horizontal scanning frequency.

18. A method according to claim 11, further comprising

using a receiver to receive the subsequently transmitted primary color video signal with the carrier burst.

19. A method for injecting a secondary signal carrier burst into a color video signal, the method comprising:

providing a color video signal having active lines and blanking intervals at a predetermined rate with a horizontal blanking period with a front porch and a back porch in at least some blanking intervals and having a color carrier burst on the back porch;

generating a tertiary carrier having a frequency and timing signals based upon the rate of at least some of the blanking intervals; and

injecting the secondary carrier burst into the primary color video signal in response to at least one of the timing signals during one of the front porch and the back porch.

20. A processor for a receiver for receiving a composite video signal which includes a primary color video signal having blanking intervals separating lines of active video and at least one other carrier, each carrier having a frequency and having a secondary rasterized modulated signal modulated with a carrier having a different frequency, the processor comprising:

a primary section for receiving the composite video signal and providing at least one timing signal based upon the rate of at least some of the blanking intervals; and

a secondary signal section for receiving a secondary signal including a carrier burst at the different frequency in the composite video signal, detecting the carrier burst in response to the timing signal, and providing a demodulated unrasterized version of the secondary signal after a detection of the carrier burst.

21. A processor for combining a primary color video signal with a secondary signal for subsequent transmission, the processor comprising:

a primary signal section providing the primary color video signal having active video lines separated by blanking intervals, the start of the blanking interval defining the end of the active video lines, and having a color carrier having a frequency;

a secondary signal section having a secondary signal carrier at a different frequency of a predetermined number of cycles per second for providing a secondary signal carrier burst and a modulation signal produced by the modulation of the secondary signal carrier modulated with a rasterized version of the secondary signal for injection into the primary color signal; and

a timing section producing a timing signal for halting the injection of the modulated secondary signal when the end of the active video line is a predetermined number of cycles of the secondary signal carrier away.

22. The processor of claim 21, wherein the predetermined interval is equal to about five cycles.

23. The processor of claim 21, wherein the timing section produces a timing signal controlling the injection of the carrier burst into the video signal so that a predetermined number of cycles is injected into the video signal immediately after the end of each blanking interval.