Television proximity sensor

1. A system comprising:

an audience measurement device to detect at least one of a code and a signature associated with a television program; and,

a television proximity sensor system including:

a sensor configured to attempt to detect a signal emitted by a transformer of a television when the television is on;

an analog-to-digital converter to convert a signal detected by the sensor into a set of digital samples; and

a digital signal processor in communication with the analog-to-digital converter, and configured to process the set of digital samples to determine if the sensor is located in proximity to a television that is turned on;

wherein an audience measurement system associated with the audience measurement device disregards the at least one of the code and the signature associated with the television program if the television proximity sensor determines that the sensor is not located in proximity to a television that is turned on.

2. The system of claim 1 , further comprising an amplifier to amplify the detected signal and to provide the amplified signal to the analog-to-digital converter.

3. A television proximity sensor system comprising:

a sensor configured to attempt to detect a signal emitted by a transformer of a television when the television is on;

an analog-to-digital converter to convert a signal detected by the sensor into a set of digital samples; and

a digital signal processor in communication with the analog-to-digital converter, and configured to process the set of digital samples to determine if the sensor is located in proximity to a television that is turned on; wherein the digital signal processor is configured to:

measure a first power level of the set of digital samples at a first frequency;

measure a second power level of the set of digital samples at a second frequency;

measure a third power level of the set of digital samples at a third frequency;

compute a ratio of the first power level to a sum of the first, second, and third power levels;

compare the computed ratio to a predetermined first threshold value; and

when the computed ratio is greater than or equal to the first threshold value, determine that the sensor is located in a same room as a television which is turned on.

4. The sensor system of claim 3 , wherein the digital signal processor is further configured to:

continuously update the measurements of the first, second and third power levels;

compare the most recent measurement of the first power level to a predetermined second threshold value;

when the first power level is greater than or equal to the second threshold value, determine that the sensor is in proximity to a television which is turned on; and

when the computed ratio is less than the first threshold value and the first power level is less than the second threshold value, determine that the sensor is not in proximity to a television that is turned on.

5. The sensor system of claim 4 , wherein the audio sensor is portable.

6. The sensor system of claim 3 , wherein the digital signal processor is further configured to use a sliding Fast Fourier Transform algorithm to process the set of digital samples.

7. The sensor system of claim 3 , wherein the predetermined first threshold value is equal to substantially 0.9.

8. The sensor system of claim 3 , wherein the predetermined first threshold value is greater than or equal to substantially 0.6.

9. The sensor system of claim 3 , wherein the first frequency is associated with a horizontal scan fly-back transformer used by the television.

10. The sensor system of claim 9 , wherein the horizontal scan fly-back transformer is associated with a frequency equal to substantially 15.75 kHz.

11. The sensor system of claim 3 , wherein the second and third frequencies have predetermined spacings from the first frequency.

12. The sensor system of claim 3 , wherein the audio sensor is portable.

13. The system of claim 1 , wherein the television proximity sensor system is disposed within the audience measurement device and the audience measurement device is portable.

14. An apparatus comprising:

an audience measurement device to collect audience measurement data;

receiving means for attempting to receive a predetermined analog noise signal associated with a transformer of a television when the television is in an on state;

digitizing means for converting the received analog signal to a set of digital samples; and

processing means for processing the set of digital samples to determine if the audience measurement device is in proximity to a television which is in the on state, wherein the audience measurement device disregards the audience measurement data if the processing means determines that the audience measurement device is not located in proximity to a television that is turned on.

15. The apparatus of claim 14 , further comprising amplifying means for amplifying the received analog signal.

16. An apparatus to determine whether an audience measurement device is in proximity to a television in an on state, the apparatus comprising:

receiving means for attempting to receive a predetermined analog noise signal associated with a transformer of a television when the television is in the on state;

digitizing means for converting the received analog signal to a set of digital samples;

processing means for processing the set of digital samples to determine if the audience measurement device is in proximity to a television which is in the on state, wherein the processing means comprises:

first measuring means for measuring a first power level of the signal at a first frequency;

second measuring means for measuring a second power level of the signal at a second frequency;

third measuring means for measuring a third power level of the signal at a third frequency;

computing means for computing a ratio of the first power level to a sum of the first, second, and third power levels; and

first comparing means for comparing the computed ratio to a predetermined first threshold value,

wherein when the computed ratio is greater than or equal to the first threshold value, the processing means determines that the audience measurement device is in proximity to a television which is in the on state.

17. The apparatus of claim 16 , wherein the processing means further comprises:

updating means for continuously updating the measurements of the first, second, and third power levels; and

second comparing means for comparing the most recent measurement of the first power level to a predetermined second threshold value,

wherein when the first power level is greater than or equal to the second threshold value, the processing means determines that the audience measurement device is in proximity to a television which is in the on state; and

when the first power level is less than the second threshold value and the computed ratio is less than the first threshold value, the processing means determines that the audience measurement device is not in proximity to a television which is in the on state.

18. The apparatus of claim 17 , wherein the receiving means is portable.

19. The apparatus of claim 16 , wherein the processing means further comprises transforming means for using a sliding Fast Fourier Transform algorithm to process the set of digital samples.

20. The apparatus of claim 16 , wherein the predetermined first threshold value is equal to substantially 0.9.

21. The apparatus of claim 16 , wherein the predetermined first threshold value is greater than or equal to substantially 0.6.

22. The apparatus of claim 16 , wherein the first frequency is associated with a horizontal scan fly-back transformer used by the first television.

23. The apparatus of claim 22 , wherein the horizontal scan fly-back transformer is associated with a frequency equal to substantially 15.75 kHz.

24. The apparatus of claim 16 , wherein the second and third frequencies have predetermined spacings from the first frequency.

25. The apparatus of claim 16 , wherein the receiving means is portable.

26. The apparatus of claim 14 , wherein the receiving means is disposed within the audience measurement device, and the audience measurement device is portable.

27. A method of collecting audience measurement data comprising:

attempting to receive an analog signal corresponding to a transformer signal of the television set;

converting the received analog signal to a set of digital samples;

processing the set of digital samples;

using a result of the processing to determine whether the television set is turned on and in near proximity;

disregarding audience measurement data detected when the television set is not turned on and in proximity.

28. The method of claim 27 , further comprising amplifying the received analog signal.

29. A method of determining whether a television set is turned on and in near proximity comprising:

receiving an analog signal corresponding to a transformer signal of the television set;

converting the received analog signal to a set of digital samples;

processing the set of digital samples; and

using a result of the processing to determine whether the television set is turned on and in near proximity; wherein the processing comprises:

measuring a first power level of the signal at a first frequency;

measuring a second power level of the signal at a second frequency;

measuring a third power level of the signal at a third frequency;

computing a ratio of the first power level to a sum of the first, second, and third power levels;

comparing the computed ratio to a predetermined first threshold value; and

when the computed ratio is greater than or equal to the first threshold value, determining that the television set is turned on and in near proximity.

30. The method of claim 29 , wherein the processing further comprises:

continuously updating the measurements of the first, second, and third power levels;

comparing the most recent measurement of the first power level to a predetermined second threshold value;

when the first power level is greater than or equal to the second threshold value, determining that the television set is turned on and in near proximity; and

when the first power level is less than the second threshold value and the computed ratio is less than the first threshold value, determining that the television is turned off or out of proximity.

31. The method of claim 30 , wherein receiving an analog signal corresponding to a transformer signal of the television set comprises detecting the analog signal using a portable detecting device.

32. The method of claim 29 , wherein processing further comprises using a sliding Fast Fourier Transform algorithm.

33. The method of claim 29 , wherein the predetermined first threshold value is equal to substantially 0.9.

34. The method of claim 29 , wherein the predetermined first threshold value is greater than or equal to substantially 0.6.

35. The method of claim 29 , wherein the first frequency is associated with a horizontal scan fly-back transformer used by the television set.

36. The method of claim 35 , wherein the horizontal scan fly-back transformer is associated with a frequency equal to substantially 15.75 kHz.

37. The method of claim 29 , wherein the second and third frequencies have predetermined spacings from the first frequency.

38. The method of claim 29 , wherein receiving an analog signal corresponding to a transformer signal of the television set comprises detecting the analog signal using a portable detecting device.

39. The method of claim 27 , wherein receiving an analog signal corresponding to a transformer signal of the television set comprises detecting the analog signal using a portable detecting device.

40. A method of detecting whether a first television set is turned on comprising:

measuring a first power level of a signal at a first frequency, the first frequency being associated with a horizontal scan fly-back transformer used by the first television set;

measuring a second power level of the signal at a second frequency and a third power level of the signal at a third frequency, the second and third frequencies having predetermined spacings from the first frequency;

computing a ratio of the first power level to a sum of the first, second, and third power levels;

making a first comparison of the ratio to a predetermined threshold ratio value; and

making a first determination of whether the first television set is turned on based on a result of the first comparison.

41. The method of claim 40 , further comprising:

using a measured value of the first power level to set a threshold first power value;

continuously updating the measurements of the first, second, and third power levels; and

when a first determination that the television set is not turned on is made;

making a second comparison of a most recently updated measurement value of the first power level to the threshold first power value; and

making a second determination of whether the television set is turned on based on a result of the second comparison.

42. The method of claim 41 , measuring a first power level of the signal at a first frequency comprises detecting the signal using a portable detecting device.

43. The method of claim 40 , wherein measuring a first power level of the signal at a first frequency comprises detecting the signal using a portable detecting device.

44. A method comprising:

attempting to detect a noise signal associated with a television with a portable audience measurement device;

if a noise signal is not detected with the portable audience measurement device, determining that the portable audience measurement device is not in proximity to a television in an on state;

if a noise signal is detected with the portable audience measurement device, determining if the noise signal is indicative of the portable audience measurement device being in proximity to a television in an on state;

if the noise signal is indicative of the portable audience measurement device being in proximity to a television in an on state, collecting any detected audience measurement data; and

if the noise signal indicates that the portable audience measurement device is not in proximity to a television in an on state, disregarding any detected audience measurement data.

45. A method as defined in claim 44 wherein attempting to detect a noise signal comprises attempting to detect a noise signal generated by a transformer of a television when the television is in an on state.

46. A method of determining if a sensor is in proximity to a television in an on state comprising:

attempting to detect a noise signal associated with a television;

if a noise signal is not detected, determining that the sensor is not in proximity to a television in an on state; and

if a noise signal is detected, determining if the noise signal is indicative of the sensor being in proximity to a television in an on state;

wherein attempting to detect a noise signal comprises attempting to detect a noise signal generated by a transformer of a television when the television is in an on state; and wherein determining if the noise signal is indicative of the sensor being in proximity to a television in an on state comprises:

identifying a first power level of the noise signal at a first frequency, a second power level of the noise signal at a second frequency, and a third power level of the noise signal at a third frequency;

computing a ratio of the first power level to a sum of the first, second and third power levels; and

comparing the ratio to a predetermined threshold.

47. An apparatus comprising:

an audience measurement device to collect audience measurement data;

a sensor to attempt to detect a noise signal associated with a television; and

a processor to determine that the sensor is not in proximity to a television in an on state if the sensor does not detect a noise signal, and to determine if a noise signal detected by the sensor is indicative of the sensor being in proximity to a television in an on state, wherein the audience measurement device collects the audience measurement data if the processor determines that the noise signal detected by the sensor is indicative of the sensor being in proximity to a television in an on state, but the audience measurement device disregards the audience measurement data if the processor determines that the sensor is not in proximity to a television in an on state.

48. An apparatus as defined in claim 47 wherein the sensor and processor are located in a portable audience measurement device.

49. An apparatus as defined in claim 47 wherein the noise signal the sensor attempts to detect comprises a noise signal generated by a transformer of a television when the television is in an on state.

50. An apparatus comprising:

a sensor to attempt to detect a noise signal associated with a television; and

a processor to determine that the sensor is not in proximity to a television in an on state if the sensor does not detect a noise signal, and to determine if a noise signal detected by the sensor is indicative of the sensor being in proximity to a television in an on state, wherein the processor determines if the noise signal is indicative of the sensor being in proximity to a television in an on state by;

identifying a first power level of the noise signal at a first frequency, a second power level of the noise signal at a second frequency, and a third power level of the noise signal at a third frequency;

computing a ratio of the first power level to a sum of the first, second and third power levels; and

comparing the ratio to a predetermined threshold.