Interactive video distribution systems – Use surveying or monitoring – By passively monitoring receiver operation
Reexamination Certificate
1999-03-22
2002-11-26
Miller, John (Department: 2614)
Interactive video distribution systems
Use surveying or monitoring
By passively monitoring receiver operation
C725S014000, C348S194000
Reexamination Certificate
active
06487719
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a TV channel selecting status monitoring method and apparatus and, more particularly, to a method and apparatus for determining a video/audio source and its broadcast channel to which the TV set is actually tuned.
(2) Description of the Prior Art
When a rating company monitors the channel tuning or selecting status of the TV set placed at each sample household for the purpose of audience measurement, a measuring apparatus called a TV sensor or audimeter is connected to the TV set so that the apparatus obtains TV set ON/OFF information and the number of the currently selected channel in association with time information and periodically sends them to a computer of the research center through a telephone circuit.
A source of video signals for display on the cathode-ray tube of the TV set and audio signals for output from its loudspeaker will hereinafter be referred to as a video/audio source, or simply as a source. A typical source is a VHF/UHF tuner built in the TV set. Other possible sources are a BS tuner, a CATV tuner, a CS (Communication Satellite) TV tuner, a VCR (Video Cassette Recorder), an electronic game machine, and so forth.
In the past when TV sets were usually used singly, it was necessary, for audience measurement, only to obtain the TV set ON/OFF information and the number of the channel actually selected by the VHF/UHF tuner in the TV set in association with time data. With the recent widespread use of a VCR and similar audio-visual (AV) apparatus and an AV/TV set (a TV set which has a plurality of video/audio input terminals and adapted to be used also as a monitor of an external apparatus such as a VCR), it has become necessary to detect the source actually selected by the TV set prior to the above-mentioned channel identification.
According to a conventional method (hereinafter referred to as a first conventional method) of searching for the actually selected source, audio signals to be applied from the VCR and similar sources to the TV set are each mixed with an identification signal of an inaudible frequency and are sequentially fed to individual video/audio input terminals, and a check is made to see if the identification signal is contained in each of audio signals obtained by picking up sounds from the loudspeaker of the TV set by a microphone. In this method, when the audio signal is decided as containing the identification signal, the video/audio input terminal corresponding thereto is specified as the video/audio input terminal currently selected for displaying video signals of the corresponding source on the TV set. Incidentally, when none of the video/audio input terminals are decided as being selected, it is determined that the broadcast waves are being received by the tuner in the TV set, if the TV set is ON and if the channel concerned can be specified.
On the other hand, there has been proposed a method (hereinafter referred to as a second conventional method) for detecting the channel on which video signals are actually displayed on the TV screen. This method detects a local oscillation signal of the tuner in the TV set to be monitored, and detects the currently receiving channel from the frequency of the oscillation signal through utilization of a one-to-one correspondence between them.
Another conventional method (hereinafter referred to as a third conventional method) is one that obtains an audio signal from the TV set and compares it with an audio signal of each channel played back by a reference receiver independently of the TV set, thereby identifying the currently selected by the TV set.
However, the first conventional method is applicable only to the TV set of the type that contains the VHF/UHF tuner alone, and is not applicable to TV sets of the type having incorporated therein one or more tuners as well as the VHF/UHF tuner, such as an AV/TV set containing a BS tuner and an AV/TV set containing a VCR built-in. The reason for this is, for example, that in the AV/TV set containing a BS tuner built-in, the BS broadcast wave bypasses video/audio input terminals and directly reaches the TV set. Accordingly, when no video/audio input terminals are selected, it is impossible to distinguish between the VHF/UHF and BS broadcasts although it is known that the actually selected source is either one of them. The same is true of the AV/TV set with a VCR built therein.
The second conventional method is applicable only to a TV set which receives analog broadcast waves alone, and is not suitable for application to a TV set which receives CS digital broadcast and like digital broadcasts as well. The CS digital broadcast digitizes video signals for data compression and transmits four to eight channels on a time-division multiplex basis through a single transponder. This makes it impossible to specify that one of the channels to which the tuner of the CS digital broadcast receiver is tuned, even if its channel selecting status is detected through utilization of the local oscillation frequency.
A third conventional method involves direct comparison of audio signals for the channel identification, and is applicable to such a digital broadcast as the CS digital broadcast as well as to the existing ground wave analog broadcast. With this method, however, it is often impossible to detect channels because there are cases where a silent period continues for a long time in TV programs.
A possible modification of the third conventional method is to use video signals in place of audio signals. That is, the video signal displayed on the TV screen is compared directly with the video signal on each of channels generated by reference receivers independently of the TV set; the channels selected by the reference receivers are changed until the both video signals coincide, and the channel for which the video signals coincide is specified as the channel currently selected. With this method, however, relatively much time is required for the comparison of video signals for each channel. Hence, the channel identification by the comparison of video signals for every channel inevitably consumes a large amount of time.
Moreover, the method by the direct comparison of video signals is based on the premise that the video signals for comparison can be generated in the monitoring apparatus independently of the TV set. Accordingly, in the CATV broadcast which uses video signals scrambled by suppression of sync signals—recently widespread in urban areas—the video signals for comparison cannot be generated, and hence the channel identification is impossible. In the CATV broadcast, a pay channel is scrambled and a descramble signal is sent to contracted TV sets to descramble the video signals. However, the CATV receiver mounted in the monitoring apparatus is not formally contracted and hence is not supplied with the descramble signal; therefore, the video signals for comparison cannot be generated in the monitoring apparatus.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a TV channel selecting status monitoring method and apparatus which permits detection of which source is being selected in a TV set which contains a plurality of sources such as a BS tuner and a VHF/UHF tuner and is also adapted for use as a monitor of an external source such as a CATV tuner.
Another object of the present invention is to provide a TV channel selecting status monitoring method and apparatus which, after the identification of a video/audio source actually selected by the user, permit efficient detection of that one of channels of video/audio source which is actually selected by the user.
Another object of the present invention is to provide a TV channel selecting status monitoring method and apparatus which, when candidate channels cannot be narrowed down to one particular channel actually selected by the user through the comparison of sync signals, permit ultimate detection of the actually selected channel by the comparison of video signals.
Still another object of the prese
Itoh Yosikazu
Tanaka Hiroshi
Beliveau Scott
K. K. Video Research
Miller John
Sughrue & Mion, PLLC
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