Ensuring EAS performance in audio signal encoding

1. A method of encoding an ancillary code in broadcast audio data while preserving detectability of an Emergency Alert System (EAS) code therein, comprising the steps of:

receiving broadcast audio data;

encoding the broadcast audio data with an ancillary code having a first magnitude;

providing reference data corresponding to an EAS code;

monitoring for an EAS code by comparing the reference data with at least a portion of the broadcast audio data, to produce a match of the reference data with an EAS code present in the broadcast audio data; and

modifying the first magnitude of the ancillary code to reduce the same to a zero level in response to the match, such that detectability of the EAS code in the broadcast audio data in accordance with a predetermined detection method is preserved.

2. The method according to claim 1 wherein the step of monitoring for an EAS code further comprises the step of correlating data points from the broadcast audio data with the reference data to produce a correlation value.

3. The method according to claim 2 further comprising the step of determining whether the correlation value is above a predetermined threshold value to produce the match.

4. The method according to claim 1 wherein the step of monitoring for an EAS code further comprises the step of correlating data points from a received signal with the reference data to detect data in the broadcast audio data having a predetermined EAS frequency.

5. The method according to claim 1 wherein the ancillary code comprises a sequence of code symbols each represented as a plurality of substantially single-frequency code components.

6. The method according to claim 1 wherein the monitored EAS code comprises an AFSK code.

7. The method according to claim 1 wherein the reference data has a defined frequency pattern and defined amplitude that correlates to a preamble of the EAS code.

8. The method according to claim 7 wherein the step of monitoring for an EAS code further comprises the step of monitoring for the preamble of the EAS code.

9. The method according to claim 1 wherein the first magnitude of the ancillary code is reduced to a zero level for a predetermined time period.

10. The method according to claim 9 wherein the first magnitude of the ancillary code is restored after the expiration of the predetermined time period.

11. The method according to claim 9 further comprising the step of restarting the predetermined time period each time the EAS code is detected.

12. A method of encoding an ancillary code in media data comprising the steps of:

receiving the media data; encoding the media data with a first ancillary code having predetermined code characteristics and a first code detection priority;

providing reference data corresponding to a second ancillary code having a second code detection priority higher than the first code detection priority and present from time to time in the media data;

comparing the reference data with at least a portion of the media data, to produce a match of the reference data with the second ancillary code when present therein; and

modifying at least one of the predetermined characteristics of the first ancillary code to reduce the same to a zero level in response to the match, to ensure detectability of the second ancillary code in the media data in accordance with a predetermined detection method.

13. The method according to claim 12 wherein the reference data corresponds to an Emergency Alert System (EAS) code.

14. The method according to claim 13 wherein the reference data has a defined frequency pattern and defined amplitude that correlates to a preamble of the EAS code.

15. The method according to claim 14 wherein the step of monitoring for an EAS code further comprises the step of monitoring for the preamble of the EAS code.

16. A method of encoding an ancillary code in media data comprising the steps of:

receiving the media data;

encoding the media data with a first ancillary code having predetermined code characteristics and a first code detection priority;

detecting a second ancillary code in or to be included in the media data to produce detection data, the second ancillary code having a second code detection priority higher than the first code detection priority; and

modifying at least one of the predetermined characteristics of the first ancillary code to reduce the same to a zero level for a predetermined time period in response to the detection data, to ensure detectability of the second ancillary code in the media data during the predetermined time period in accordance with a predetermined detection method.

17. The method according to claim 16 further comprising the step of providing reference data corresponding to the second ancillary code.

18. The method according to claim 17 wherein the reference data corresponds to an Emergency Alert System (EAS) code.

19. The method according to claim 18 wherein the reference data has a defined frequency pattern and defined amplitude that correlates to a preamble of the EAS code.

20. The method according to claim 19 wherein the step of monitoring for an EAS code further comprises the step of monitoring for the preamble of the EAS code.

21. The method according to claim 17 further comprising the step of restoring the predetermined code characteristics of the first ancillary code after the predetermined time period.

22. A method of encoding an ancillary code in media data comprising the steps of:

receiving the media data;

encoding the media data with a first ancillary code having predetermined code characteristics and a first code detection priority;

detecting a second ancillary code in or to be included in the media data to produce detection data, the second ancillary code having a second code detection priority higher than the first code detection priority; and

assigning a zero level to at least one of the predetermined characteristics of the first ancillary code in response to the detection data, to ensure detectability of the second ancillary code in the media data in accordance with a predetermined detection method.

23. The method according to claim 22 further comprising the step of providing reference data corresponding to the second ancillary code.

24. The method according to claim 23 wherein the reference data corresponds to an Emergency Alert System (EAS) code.

25. The method according to claim 24 wherein the reference data has a defined frequency pattern and defined amplitude that correlates to a preamble of the EAS code.

26. The method according to claim 25 wherein the step of monitoring for an EAS code further comprises the step of monitoring for the preamble of the EAS code.

27. The method according to claim 22 wherein the at least one of the predetermined characteristics of the first ancillary code is assigned a zero level for a predetermined time period.

28. The method according to claim 27 wherein the at least one of the predetermined characteristics of the first ancillary code is restored after the expiration of the predetermined time period.

29. The method according to claim 27 further comprising the step of restarting the predetermined time period each time the second ancillary code is detected.

30. A system for encoding an ancillary code in broadcast audio data while preserving detectability of an Emergency Alert System (EAS) code therein, comprising:

an encoder for encoding broadcast audio data with an ancillary code having a first magnitude;

reference data corresponding to an EAS code; and a controller for monitoring for an EAS code by comparing the reference data with at least a portion of the broadcast audio data, to produce a match of the reference data with an EAS code present in the broadcast audio data and for reducing the first magnitude of the ancillary code to a zero level in response to the match, such that detectability of the EAS code in the broadcast audio data in accordance with a predetermined detection method is preserved.

31. The system according to claim 30 wherein the controller is operative to correlate data points from the broadcast audio data with the reference data to produce a correlation value.

32. The system according to claim 31 wherein the controller is operative to determine if the correlation value is above a predetermined threshold value to produce the match.

33. The system according to claim 30 wherein the controller is operative to correlate data points from a received signal with the reference data to detect data in the broadcast audio data having a predetermined EAS frequency.

34. The system according to claim 30 wherein the ancillary code comprises a sequence of code symbols each represented as a plurality of substantially single-frequency code components.

35. The system according to claim 30 wherein the monitored EAS code comprises an AFSK code.

36. The system according to claim 30 wherein the reference data has a defined frequency pattern and defined amplitude that correlates to a preamble of the EAS code.

37. The system according to claim 36 wherein the controller is operative to monitor for the preamble of the EAS code.

38. The system according to claim 30 wherein the controller is operative to reduce the first magnitude of the ancillary code to a zero level for a predetermined time period.

39. The system according to claim 38 wherein the controller is operative to restore the first magnitude of the ancillary code after the expiration of the predetermined time period.

40. The system according to claim 38 wherein the controller is operative to restart the predetermined time period each time the EAS code is detected.

41. A system for encoding an ancillary code in media data comprising:

an encoder for encoding media data with a first ancillary code having predetermined code characteristics and a first code detection priority;

reference data corresponding to a second ancillary code having a second code detection priority higher than the first code detection priority and present from time to time in the media data;

a controller for comparing the reference data with at least a portion of the media data, to produce a match of the reference data with the second ancillary code when present therein and for modifying at least one of the predetermined code characteristics of the first ancillary code to reduce the same to a zero level in response to the match, to ensure detectability of the second ancillary code in the media data in accordance with a predetermined detection method.

42. The system according to claim 41 wherein the reference data corresponds to an Emergency Alert System (EAS) code.

43. The system according to claim 42 wherein the reference data has a defined frequency pattern and defined amplitude that correlates to a preamble of the EAS code.

44. The system according to claim 43 wherein the controller is operative to monitor for the preamble of the EAS code.

45. A system of encoding an ancillary code in media data comprising:

an encoder for encoding media data with a first ancillary code having predetermined code characteristics and a first code detection priority; and

a controller for detecting a second ancillary code in or to be included in the media data to produce detection data, the second ancillary code having predetermined code characteristics and a second code detection priority higher than the first code detection priority, the controller being operative to modify at least one of the predetermined characteristics of the first ancillary code to reduce the same to a zero level for a predetermined time period in response to the detection data, to ensure detectability of the second ancillary code in the media data during the predetermined time period in accordance with a predetermined detection method.

46. The system according to claim 45 further comprising reference data corresponding to the second ancillary code.

47. The system according to claim 46 wherein the reference data corresponds to an Emergency Alert System (EAS) code.

48. The system according to claim 46 wherein the reference data has a defined frequency pattern and defined amplitude that correlates to a preamble of the EAS code.

49. The system according to claim 48 wherein the controller is operative to monitor for the preamble of the EAS code.

50. The system according to claim 45 wherein the controller further restores the predetermined code characteristics of the first ancillary code after the predetermined time period.

51. A system of encoding an ancillary code in media data comprising:

an encoder for encoding media data with a first ancillary code having predetermined code characteristics and a first code detection priority; and

a controller for detecting a second ancillary code in or to be included in the media data to produce detection data, the second ancillary code having predetermined code characteristics and a second code detection priority higher than the first code detection priority, the controller being operative to modify at least one of the predetermined characteristics of the first ancillary code to reduce the same to a zero level in response to the detection data, to ensure detectability of the second ancillary code in the media data in accordance with a predetermined detection method.

52. The system according to claim 51 further comprising reference data corresponding to the second ancillary code.

53. The system according to claim 52 wherein the reference data corresponds to an Emergency Alert System (EAS) code.

54. The system according to claim 53 wherein the reference data has a defined frequency pattern and a defined amplitude that correlates to a preamble of the EAS code.

55. The system according to claim 54 wherein the controller is operative to monitor for the preamble of the EAS code.

56. The system according to claim 51 wherein the controller is operative to modify the at least one of the predetermined characteristics of the first ancillary code to reduce the same to a zero level for a predetermined time period.

57. The system according to claim 56 wherein the controller is operative to restore the at least one of the predetermined characteristics of the first ancillary code after the expiration of the predetermined time period.

58. The system according to claim 56 wherein the controller is operative to restart the predetermined time period each time the second ancillary code is detected.