AUDIENCE SURVEY SYSTEM

• US 3,800,223 A
• Filed: 05/04/1973
• Issued: 03/26/1974
• Est. Priority Date: 05/04/1973
• Status: Expired due to Term

• Current Assignee: Hansel B. Mead
• Original Assignee: Hansel B. Mead
• Inventors: Mead, Hansel B.
• Primary Examiner(s): Mayer, Albert J.
• Application Number:
  US05/357,177
• Time in Patent Office: 326 Days
• Field of Search: 325/31,65,322,325,332-335,341,346,363,364,416,417,420,422
• US Class Current: 725/15
• CPC Class Codes: H04H 60/43 for identifying broadcast channels

Abstract

Disclosed is a monitor for ascertaining the listening habits of television receiver users. The monitor includes one or more channels provided with a single pass band window or slot that is swept at a constant rate but stopped when a television local oscillator signal enters the window. If the signal remains in the window for a predetermined time, the signal is counted and the sweep continued. As a result, the total sweep rate or time is variable. By switching in a signal suppressor when the swept oscillator output reaches predetermined frequencies, it is possible to work closer in to strong FM signals from FM broadcast stations.

Claims

1. In a receiving set monitor having a mixer and a swept local oscillator coupled to said mixer for comparing the frequency of incoming signals with the frequency of said oscillator, means coupled to said oscillator for causing the sweep of the oscillator to stop when the frequency of an incoming signal is in a predetermined pass band, means coupled to said oscillator for restarting said oscillator sweep after said signal has been in said pass band a predetermined length of time, a receiving channel in said monitor coupled to said oscillator, an FM signal suppressor coupled to said receiving channel for suppressing large FM signals passing into said channel, and means coupling said oscillator to said suppressor for switching said suppressor into said channel at predetermined places in a sweep cycle of said oscillator.

2. Apparatus according to claim 1 wherein said switch means comprises an RF switch coupling said suppressor to said channel, and a frequency position encoder coupling said oscillator to said RF switch.

3. Apparatus according to claim 1 including means for supplying a sweep voltage from said oscillator to said position encoder whereby said encoder produces an output in response to the magnitude of said sweep voltage.

4. A monitor for ascertaining the listing habits of radio and television users comprising a plurality of channels for passing different bands of frequencies approximately three to four megahertz wide, at least one of said channels comprising a mixer, a swept oscillator coupled to said mixer for mixing the incoming signals with the swept output of said oscillator, a filter and detector coupled to the output of said mixer, means for supplying a sweep hold signal from said detector to said oscillator whereby the oscillator sweep is stopped when a signal passing through said filter is detected by said detector, an FM suppressor, and means in said one channel coupling said oscillator to said suppressor for switching said suppressor in and out of said one channel when the swept output of said oscillator is at predetermined frequencies.

5. A monitor for ascertaining the listing habits of television users comprising a signal input, a plurality of channels including frequency seclection means coupled to said input for passing different bands of frequencies into said channels, at least one of sid channels comprising a mixer, a swept oscillator coupled to said mixer for mixing the incoming signals from said signal input with the swept output of said oscillator, a band pass filter and a detector coupled to the output of said mixer, time delay means for supplying a sweep hold signal from said detector to said oscillator hwereby the sweep of said oscillator is stopped for a predetermined length of time when a signal passing through said filter is detected by said detector, means coupled to said detector and time delay means for recording a count when said signal has been detected by said detector for a predetermined length of time, a feed forward FM signal suppressor having a notch filter, an RF switch in said one channel for switching said suppressor into and out of said channel, a frequency position encoder coupling said oscillator to said RF switch, said detector including inhibiting means and means coupling an output of said frequency position encoder to said inhibiting means for inhibiting said detector when the output of said swept oscillator is at predetermined frequencies.

6. In a receiving set monitor having a mixer and a swept local oscillator coupled to said mixer for comparing the frequency of incoming signals with the frequency of said oscillator, means coupled to said oscillator for causing the sweep of the oscillator to stop when the frequency of an incoming signal is in a predetermined pass band, means coupled to said oscillator for restarting said oscillator sweep after said signal has been in saId pass band a predetermined length of time, a receiving channel in said monitor coupled to said oscillator, and an FM signal suppressor coupled to said receiving channel for suppressing large FM signals passing into said channel.

7. A monitor for ascertaining the listening habits of television users comprising a signal input, a plurality of channels including frequency selection means coupled to said input for passing different bands of frequencies into said channels, at least one of said channels comprising a mixer, a swept oscillator coupled to said mixer for mixing the incoming signals from said signal input with the swept output of said oscillator, a band pass filter and a detector coupled to the output of said mixer, time delay means for supplying a sweep hold signal from said detector to said oscillator whereby the sweep of said oscillator is stopped for a predetermined length of time when a signal passing through said filter is detected by said detector, means coupled to said detector and time delay means for recording a count when said signal has been detected by said detector for a predetermined length of time, a feed forward FM signal suppressor having a notch filter, an RF switch in said one channel for switching said suppressor into and out of said channel, and a frequency position encoder coupling said oscillator to said RF switch.

8. In a receiving set monitor having a mixer and a swept local oscillator coupled to said mixer for comparing the frequency of incoming signals with the frequency of said oscillator, a detector and a decision logic circuit coupled to said mixer, means for supplying a sweep hold signal from said decision logic circuit to said oscillator, and a time delay circuit in said decision logic circuit for terminating said sweep hold signal after a predetermined length of time, said decision logic circuit including a filter having a variable time constant coupled to the output of said detector, and means coupled to said filter for varying its time constant in response to an output signal from said detector.

9. Apparatus according to claim 8 wherein said filter is a low pass video filter.

10. Apparatus according to claim 9 including a limiter coupled to said mixer, said detector comprising an AM detector coupled to the output of said limiter.

11. Apparatus according to claim 10 including a level detector coupled to the output of said filter, and means for feeding back a signal from said level detector to said filter for varying the time constant of said filter.

12. Apparatus according to claim 11 wherein said feedback means comprises means for increasing the time constant of said low pass filter in response to an output from said level detector.

13. Apparatus according to claim 12 wherein said feedback means comprises an MOSFET coupled between the output of said level detector and said filter.

14. Apparatus according to claim 13 including an integrator coupling the output of said level detector to the gate of said MOSFET.

15. Apparatus according to claim 14 wherein said means for supplying a sweep hold signal to said oscillator is coupled to the output of said level detector.

16. Apparatus according to claim 15 wherein said time delay circuit comprises a timer coupled to the output of said level detector.

17. Apparatus according to claim 16 including a count output coupled to the output of said timer, and means coupled between the output of said timer and said low pass filter for reducing the time constant of said low pass filter to its original value in response to an output from said timer.