Video and data co-channel communication system

• US 5,737,026 A
• Filed: 06/07/1995
• Issued: 04/07/1998
• Est. Priority Date: 02/28/1995
• Status: Expired due to Fees

• Current Assignee: Nielsen Media Research, Inc. (Nielsen Holdings plc)
• Original Assignee: Nielsen Media Research, Inc. (Nielsen Holdings plc)
• Inventors: Dougherty, Robert A., Wheeler, Henry B., Lu, Daozheng, Aust, Edgar W.
• Primary Examiner(s): LEE, MICHAEL
• Application Number:
  US08/482,820
• Time in Patent Office: 1,035 Days
• Field of Search: 348/473, 348/476, 348/477, 348/478, 348/479, 348/1, 348/2, 348/4, 348/461, 348/464, 348/467, 348/460
• US Class Current: 348/473
• 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
• CPC Class Codes: H04N 7/08 Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band , e.g. by time division H04N7/007 takes precedence
• CPC Class Codes: H04N 7/081 the additional information signals being transmitted by means of a subcarrier

Abstract

In the present invention, ancillary data is modulated onto a carrier frequency which is within a low energy density portion of a frequency band of a video signal, and the modulated carrier data is combined with the video signal so that the modulated carrier is in an overscan region of the video signal. The ancillary data may be spread over several frequencies and summed at the output of a decoder to enhance the legibility of the ancillary data at the output of the decoder. Frequency-stepping may be used to add the ancillary data at ones of a plurality of selected frequencies within the frequency band of the video signal. The ancillary data may be hierarchically apportioned between respective uniquely specified sequential segments corresponding to many distribution points of the video signal. This hierarchical ancillary data may be frequency-interleaved between harmonics of the horizontal sync frequency of the video signal. The ancillary data may be redundantly added above and below the roll-off frequency of a VCR.

Claims

1. A system for transmitting ancillary data in the same communication channel as a video signal, wherein the video signal has a frequency band and an overscan region, the system comprising:

selecting means for selecting a carrier having a carrier frequency within a low energy density portion of the frequency band;

modulating means for modulating ancillary data onto the selected carrier to produce a modulated carrier; and

,

adding means for adding the modulated carrier to the overscan region of the video signal.

2. The system recited in claim 1 wherein:

the ancillary data is first ancillary data;

the carrier is a first carrier;

the carrier frequency is a first carrier frequency;

the modulated carrier is a first modulated carrier;

the selecting means selects a second carrier having a second carrier frequency within the low energy density portion of the frequency band; and

,

the modulating means modulates the first ancillary data onto the first carrier to produce the first modulated carrier and second ancillary data onto the second carrier to produce a second modulated carrier.

3. The system recited in claim 2 wherein:

the video signal includes at least first and second horizontal scan lines in the overscan region;

the adding means adds the first modulated carrier to the video signal so that the first ancillary data is on the first horizontal scan line; and

,

the adding means adds the second modulated carrier to the video signal so that the second ancillary data is on the second horizontal scan line.

4. The system recited in claim 2 wherein:

the video signal includes at least first and second horizontal scan lines in the overscan region;

the first ancillary data is a first ancillary data bit;

the second ancillary data is a second ancillary data bit;

the modulating means modulates the first ancillary data bit onto the first carrier to produce the first modulated carrier and the second ancillary data bit onto the second carrier to produce the second modulated carrier;

the adding means adds the first modulated carrier to the video signal so that the first ancillary data bit is on the first horizontal scan line; and

,

the adding means adds the second modulated carrier to the video signal so that the second ancillary data bit is on the second horizontal scan line.

5. The system recited in claim 1 wherein:

the video signal includes at least first and second horizontal scan lines in the overscan region;

the adding means adds the modulated carrier to the video signal such that the first horizontal scan line of the video signal carries a single ancillary data bit; and

,

the adding means adds the modulated carrier to the video signal such that the second horizontal scan line of the video signal carries a single ancillary data bit.

6. The system recited in claim 1 wherein:

the video signal includes eight horizontal scan lines in the overscan region; and

,

the adding means adds the modulated carrier to the video signal such that each of the eight horizontal scan lines of the video signal carries a single corresponding ancillary data bit.

7. The system recited in claim 1 wherein:

the video signal has a horizontal sync period;

the selecting means selects the carrier having a carrier frequency within the frequency band at the beginning of each of a plurality of frequency stepping periods; and

,

each frequency stepping period has a duration equal to, or an integer multiple of, the horizontal sync period.

8. The system recited in claim 7 wherein:

the selecting means comprises means for selecting a carrier having a plurality of carrier frequencies; and

,

each of the carrier frequencies is within the frequency band and is selected at the beginning of a corresponding one of the frequency stepping periods.

9. The system recited in claim 8 wherein:

the video signal has a horizontal sync frequency; and

,

each of the carrier frequencies is substantially centered about a corresponding odd multiple of half the horizontal sync frequency.

10. The system recited in claim 7 wherein the video signal has a frame period, and wherein each frequency stepping period is equal to, or greater than, the frame period.

11. The system recited in claim 10 wherein:

the video signal has a horizontal sync frequency;

the selecting means comprises means for selecting a carrier having a plurality of carrier frequencies;

each of the carrier frequencies is within the frequency band and is selected at the beginning of a corresponding one of the frequency stepping periods; and

,

each of the carrier frequencies is substantially centered about a corresponding odd multiple of half the horizontal sync frequency.

12. The system recited in claim 7 wherein:

the ancillary data includes a time-varying code;

the selecting means, the modulating means, and the adding means comprise a plurality of encoders;

a first encoder of the plurality of encoders adds a first segment of the time varying code having a first predetermined carrier frequency;

the first segment comprises a sequence initiating input;

a second encoder of the plurality of encoders comprises a clock having a current time value as an output;

the second encoder of the plurality of encoders further comprises a memory having stored therein the frequency stepping periods, a plurality of values of the carrier frequency, and a pseudo-random sequence; and

,

the second encoder of the plurality of encoders reads the first code segment and selects, by use of the pseudo-random sequence at the beginning of a frequency stepping period, the values of the carrier frequency.

13. The system recited in claim 1 wherein:

the selecting means selects a plurality of carriers;

each carrier has a correspondingly unique carrier frequency within the frequency band;

the modulating means redundantly modulates the ancillary data onto each of the selected carriers;

the adding means adds the redundantly modulated carriers to the video signal; and

,

the system further comprises demodulating means for demodulating the ancillary data from the redundantly modulated carriers.

14. The system recited in claim 13 wherein the demodulating means comprises summing means for summing the ancillary data demodulated from a first of the redundantly modulated carriers with the ancillary data demodulated from a second of the redundantly modulated carriers.

15. The system recited in claim 13 wherein the demodulating means comprises comparing means for comparing the ancillary data demodulated from a first of the redundantly modulated carriers with the ancillary data demodulated from a second of the redundantly modulated carriers.

16. The system recited in claim 15 wherein the demodulating means comprises summing means for summing the ancillary data demodulated from a first of the redundantly modulated carriers with the ancillary data demodulated from a second of the redundantly modulated carriers.

17. The system recited in claim 1 wherein:

the system is a metering and monitoring system for metering tuning of television programs in a sampled house-hold and for monitoring broadcasts of television programs;

the television programs are transmitted by way of the video signal;

the carrier is a first carrier;

the carrier frequency is a first carrier frequency;

the selecting means selects a second carrier having a second carrier frequency within the low energy density portion of the frequency band;

the modulating means modulates first ancillary data onto the first carrier and modulates second ancillary data onto the second carrier;

the first and second carrier frequencies are within the frequency band of the video signal;

the metering and monitoring system further includes metering means for metering television tuning by detecting the first ancillary data; and

,

the metering and monitoring system further includes monitoring means for monitoring broadcasts of television programs by detecting the second ancillary data.

18. The system recited in claim 17 wherein:

the first carrier frequency is below a roll-off frequency of a VCR; and

,

the second carrier frequency is above the roll-off frequency of the VCR.

19. The system recited in claim 17 wherein:

the first carrier frequency includes a first group of carrier frequencies;

the second carrier frequency includes a second group of carrier frequencies;

the first group of carrier frequencies are below a roll-off frequency of a VCR; and

,

the second group of carrier frequencies are above the roll-off frequency of the VCR.

20. The system recited in claim 17 wherein the video signal has a chrominance subcarrier frequency, wherein the first carrier frequency is below the chrominance subcarrier frequency, and wherein the second carrier frequency is above the chrominance subcarrier frequency.

21. The system recited in claim 17 wherein:

the selecting means selects a third carrier having a third carrier frequency within the low energy density portion of the frequency band; and

,

the modulating means modulates third ancillary data onto the third carrier.

22. The system recited in claim 21 wherein;

the first carrier frequency is below a roll-off frequency of a VCR;

the second carrier frequency is above the roll-off frequency of the VCR but below a chrominance subcarrier frequency of the video signal; and

,

the third carrier frequency is above the chrominance subcarrier frequency of the video signal.

23. The system recited in claim 21 wherein:

the first carrier frequency includes a first group of carrier frequencies;

the second carrier frequency includes a second group of carrier frequencies;

the third carrier frequency includes a third group of carrier frequencies;

the first group of carrier frequencies are below a roll-off frequency of a VCR;

the second group of carrier frequencies are above the roll-off frequency of a VCR but below a chrominance subcarrier frequency of the video signal; and

,

the third group of carrier frequencies are above the chrominance subcarrier frequency of the video signal.

24. The system recited in claim 1 wherein:

the ancillary data includes a time-varying ancillary code;

the modulating means is located within a sampled household and modulates the time-varying ancillary code onto the carrier;

the system further includes non-intrusive acquiring means adjacent a display of the video signal for non-intrusively acquiring the modulated carrier; and

,

the system further includes demodulating means for demodulating the time-varying ancillary data from the modulated carrier.

25. The system recited in claim 24 wherein the non-intrusive acquiring means comprises a video probe.

26. The system recited in claim 25 wherein video probe comprises a foil tuned pickup located near the rear end of a picture tube.

27. The system recited in claim 24 wherein the non-intrusive acquiring means comprise an intermediate frequency probe.

28. The system recited in claim 24 wherein the broadcast television signal comprises a co-channel transmitted time-varying ancillary data signal.

37. The system recited in claim 1 wherein:

the overscan region comprises n overscan regions;

n is an integer; and

,

n is effectively increased by a number of carrier frequencies added to the n overscan regions.

38. The system recited in claim 37 wherein n=1.

39. The system recited in claim 37 wherein n>

1.

29. A method for transmitting ancillary data in the same communication channel as a video signal, wherein the video signal has a frequency band and corner overscan regions, the method comprising the steps of:

selecting a carrier having a carrier frequency within a low energy density portion of the frequency band;

modulating ancillary data onto the selected carrier to produce a modulated carrier; and

,

adding the modulated carrier to one of the corner overscan regions of the video signal.

30. The method recited in claim 29 wherein:

the ancillary data is first ancillary data;

the carrier is a first carrier;

the carrier frequency is a first carrier frequency;

the modulated carrier is a first modulated carrier;

the step of selecting a carrier comprises the step of selecting a second carrier having a second carrier frequency within the low energy density portion of the frequency band; and

,

the step of modulating the ancillary data comprises the steps of modulating the first ancillary data onto the first carrier to produce the first modulated carrier and modulating second ancillary data onto the second carrier to produce a second modulated carrier.

31. The method recited in claim 30 wherein:

the video signal includes at least first and second horizontal scan lines in the corner overscan regions; and

,

the adding step comprises the steps of adding the first modulated carrier to the video signal so that the first ancillary data is on the first horizontal scan line and adding the second modulated carrier to the video signal so that the second ancillary data is on the second horizontal scan line.

32. The method recited in claim 30 wherein:

the video signal includes at least first and second horizontal scan lines in the overscan region;

the first ancillary data is a first ancillary data bit;

the second ancillary data is a second ancillary data bit; and

,

the step of modulating the ancillary data comprises the steps of modulating the first ancillary data bit onto the first carrier to produce the first modulated carrier and modulating the second ancillary data bit onto the second carrier to produce the second modulated carrier;

the adding step comprises the steps of (i) adding the first modulated carrier to the video signal so that the first ancillary data bit is on the first horizontal scan line, and (ii) adding the second modulated carrier to the video signal so that the second ancillary data bit is on the second horizontal scan line.

33. The method recited in claim 29 wherein:

the video signal includes at least first and second horizontal scan lines in the corner overscan regions; and

,

the adding step comprises the steps of adding the modulated carrier to the video signal such that the first horizontal scan line of the video signal carries a single corresponding ancillary data bit and adding the modulated carrier to the video signal such that the second horizontal scan line of the video signal carries a single corresponding ancillary data bit.

34. The method recited in claim 29 wherein:

the video signal includes eight horizontal scan lines in the corner overscan regions; and

,

the adding step comprises the step of adding the modulated carrier to the video signal such that each of the eight horizontal scan lines of the video signal carries a single corresponding ancillary data bit.

35. The method recited in claim 29 wherein:

the ancillary data includes a plurality of hierarchical ancillary codes to be added to the video signal;

each hierarchical ancillary code comprises a time datum and a location datum;

each location datum is uniquely associated with one of a plurality of encoders;

each encoder has uniquely associated therewith a corresponding one of a plurality of carrier frequencies;

each carrier frequency of the plurality of carrier frequencies is in the frequency band;

the step of modulating the ancillary data comprises the step of modulating each hierarchical ancillary code onto a carrier having a corresponding one of the plurality of carrier frequencies; and

,

the step of adding the modulated ancillary data to the video signal comprises the step of adding each modulated carrier frequency to the video signal.

36. The method recited in claim 35 wherein:

the video signal has a horizonal sync frequency associated therewith; and

,

each carrier frequency of the plurality of carrier frequencies is substantially centered about an odd multiple of half the horizontal sync frequency.