Transmitting a secondary signal with dynamic injection level control

• US 5,559,559 A
• Filed: 06/14/1993
• Issued: 09/24/1996
• Est. Priority Date: 06/14/1991
• Status: Expired due to Fees

• Current Assignee: WAVO Corporation
• Original Assignee: WavePhore, Inc.
• Inventors: Schur, Christopher J., Montgomery, Gerald D., Jungo, Charles
• Primary Examiner(s): Metjahic, Safet
• Application Number:
  US08/076,199
• Time in Patent Office: 1,198 Days
• Field of Search: 348/473-475, 348/461, 348/432, 348/433, 348/436, 348/665, 348/607, 348/608, 348/478, 348/464, 348/468, 348/476, 348/17, 348/13, 348/12, 348/6, 348/678, 348/697, 348/680 , 348/426, 348/470, 348/385, 348/386, 348/384, 348/387, 348/391, 348/427, 348/429
• US Class Current: 348/432.1
• 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 video signal. The injection level of the secondary signal is dynamically controlled to reduce transmission errors in the secondary signal, and to minimize interference and power level limitations. The injection level of the secondary signal may be based on video analysis of the primary signal or on error information fed back from a receiver which receives the transmitted secondary signal.

Claims

1. A processor for combining a primary color video signal having a luminance and a chrominance portion with the chrominance portion being in an upper portion of a bandwidth of the video signal with a color carrier in the upper portion and a power level with a secondary signal having a bandwidth greater than 100 KHZ for subsequent transmission, the processor comprising:

a primary signal section providing the primary video signal after attenuating a portion of the primary video signal within the band and above the color carrier;

a secondary signal section providing a rasterized version of the secondary signal for injection into the primary video signal; and

a dynamically controlled level injector for injecting the rasterized secondary signal into the attenuated portion of the primary video signal at different injection levels into the primary video signal.

2. A processor according to claim 1, wherein the dynamically controlled level injector includes a gain controlled amplifier.

3. A processor according to claim 1, further comprising a video analyzer analyzing a power level of at least one portion of the primary video signal and providing a control signal to the dynamically controlled level injector based upon the power level, and wherein the dynamically controlled level injector alters the injection level of the secondary signal in response to the control signal.

4. A processor according to claim 3, wherein the injection level of the secondary signal substantially matches the attenuated power of the analyzed portion of the primary video signal.

5. A processor according to claim 3, responsive to error information representative of transmission errors detected in the reception of the secondary signal, and wherein the dynamically controlled level injector alters the injection level of the secondary signal to reduce errors in response to the error information and the control signal.

6. A processor according to claim 1, responsive to error information representative of transmission errors in receiving the secondary signal, and wherein the dynamically controlled level injector alters the injection level of the secondary signal to reduce errors in response to the error information.

7. A processor according to claim 6, wherein the dynamically controlled level injector decreases the injection level of the secondary signal in response to certain conditions of the error information indicating an error rate below a predetermined level.

8. A processor according to claim 6, wherein the error information fails to indicate an error for a time interval, and the dynamically controlled level injector decreases the injection level of the secondary signal.

9. A processor according to claim 1, wherein the secondary signal is injected such that the secondary signal is at least partially frequency interleaved within the primary video signal.

10. The processor of claim 1, further including:

a video analyzer for analyzing the average power in at least one portion of the spectrum of the video signal over a predetermined time interval; and

a controller responsive to the analyzer and altering the injection level of the rasterized secondary signal in a predetermined relationship to the average power level such that interference from the rasterized secondary signal is not visually perceptible at a television receiving the combined signal.

11. The processor of claim 10, wherein the analyzer analyzes the average power in at least two different portions of the spectrum.

12. The processor of claim 11, wherein the first portion is within the luminance bandwidth and the second portion is within the chrominance bandwidth.

13. A method of combining a primary video signal having a bandwidth with upper and lower ends, a luminance portion an a color portion nearer the upper end and a color carrier with a secondary signal having a bandwidth greater than 100 KHz for subsequent transmission based upon a control signal, the method comprising:

attenuating a part of the color portion above the color carrier;

rasterizing the secondary signal for injection into the primary video signal;

dynamically controlling an injection level to different levels for the secondary signal; and

injecting the secondary signal into the primary video signal in the attenuated portion.

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

analyzing a power level of at least one portion of the primary video signal;

generating a control signal based upon the power level of the analyzed portion of the primary video signal; and

altering the injection level of the rasterized secondary signal in response to the control signal.

15. A method according to claim 14, further comprising attenuating the power level of the analyzed portion of the primary video signal before injection of the secondary signal.

16. A method according to claim 15, further comprising substantially matching the injection level of the rasterized secondary signal to the attenuated power level of the analyzed portion of the primary video signal.

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

changing the control signal to respond to error information representative of transmission errors in receiving the secondary signal; and

dynamically altering the injection level of the rasterized secondary signal in response to the control signal to reduce errors.

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

responding to error information representative of transmission errors in receiving the secondary signal; and

increasing the injection level of the rasterized secondary signal to reduce errors in response to the error information.

19. A method according to claim 18, further comprising dynamically decreasing the injection level of the secondary signal in response to certain conditions of the error information indicating an error rate below a predetermined level.

20. A method according to claim 18, further comprising decreasing the injection level of the secondary signal after the error information fails to indicate an error for a time interval.

21. A method according to claim 13, further comprising injecting the rasterized secondary signal such that secondary signal is at least partially frequency interleaved within the primary video signal.

22. The method of claim 13, wherein the rasterized secondary signals are amplitude modulated before injection.

23. The method of claim 14, wherein at least a portion of the primary video signal has an average power and the method further comprises:

increasing the injection level of the secondary signal when the controller signal indicates that the average power has increased such that the data is not visually perceptible as interference to a television receiver; and

decreasing the injection level of the secondary signal when the control signal indicates that the power has decreased such that the data is not visually perceptible as interference to a television receiver.

24. The method of claim 23, wherein the analyzed portions of the video signal comprise a portion in the luminance portion of the primary video signal and in the chrominance portion of the signal.

25. The method of claim 24, wherein the injection level is increased in response to an increase above a predetermined amount in the power of either the chrominance or the luminance portion of the primary video signal.

26. The method of claim 24, wherein the injection level is altered according to a predetermined relationship so that there are no visually perceptible effects of the data in a television receiver receiving the combined signal.

27. The method of claim 24, wherein the injection level is altered according to a stored relationship.