JPH044696A - Channel measuring method - Google Patents

Abstract

PURPOSE:To realize the device with simple constitution and to realize a stable operation without need of delicate adjustment by discriminating whether or not a result of sampling a video signal of a measurement object device according to a prescribed timing follows a prescribed sequence of a GCR signal and having only to vary channels till the result is affirmative so as to measure the channel. CONSTITUTION:A sample-and-hold circuit 6 gives a value resulting from sampling and holding a video signal acquired from a measurement object device 2 with a timing signal given from a timing detection circuit 5 to a control discrimination section 7. The control discrimination section 7 discriminates whether or not a value of the sample-and-hold circuit 6 is 10100101 in an 8-field sequence and a channel of a tuner 4 is varied when the result is not satisfied regardless that the value is monitored over a prescribed period. Reception channels are varied till the sampled value is recognized to follow to a prescribed sequence and a channel whose change is stopped is discriminated to be the reception channel of the measurement object device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a channel measurement method for measuring the reception channel of a device to be measured, such as a TV station or a video tape recorder, in audience rating measurement.

[Conventional technology]

In order to automatically measure television audience ratings, it is necessary to accurately measure the reception channels of devices to be measured, such as television sets and video tape recorders.

Conventionally, there are various methods for measuring channels of this type. For example, a typical method is to detect the local oscillation signal of a tuner built into the device to be measured and measure the channel based on its frequency etc. .

[Problem to be solved by the invention]

As described above, various channel measurement methods have been proposed and put into practical use, but most of them are generally analog methods, which do not necessarily provide stable operation. For example, with the method of detecting the tuner's local oscillation signal described above, first of all, it is difficult to detect the weak local oscillation signal, and it also requires a complicated circuit to accurately measure the receiving channel from the detected local oscillation signal. In addition, subtle adjustments were also essential.

The present invention has been proposed in view of the above points, and its purpose is to stably control reception channels with a simple configuration by using ghost canceller control signals (GCR signals) that are expected to become popular in the future. An object of the present invention is to provide a method for measuring channels.

Here, the GCR signal is a signal inserted into a video signal by a broadcasting station in order to remove ghost interference appearing on a television screen.

[Means to solve the problem]

In order to achieve the above object, the present invention acquires a video signal by receiving a television broadcast independently of the device to be measured, detects the timing at which a GCR signal is inserted from this video signal, and detects the timing at which a GCR signal is inserted from the device to be measured. sampled at the timing when a video signal is detected, and changes the reception channel until it is recognized that the sampled values follow a predetermined sequence, and determines that the channel that stops changing is the reception channel of the device to be measured. ).

[Effect]

In the channel measurement method of the present invention, a video signal is obtained by receiving a television broadcast independently of the device to be measured, and the timing at which a GCR signal is inserted is detected from this video signal. The video signal is sampled at the timing when the video signal is detected.

Here, each broadcasting station broadcasts using its own synchronization signal, and the GCR signal is sent out according to a predetermined sequence, so unless the device being measured is receiving the same channel, the sampled value will not match. There is no recognition that a predetermined sequence has been followed.

Therefore, by changing the receiving channel until it is recognized that the sampled values follow a predetermined sequence and continuing this, it is possible to determine that the channel that has stopped changing is the receiving channel of the device to be measured.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a channel measuring device to which the channel measuring method of the present invention is applied. In FIG. 1, the channel measuring device 3 of this embodiment is connected to the receiving antenna 1 in order to receive broadcasts independently of the bag W2 to be measured, and also to obtain the video signal being received from the device to be measured 2. connected so that Here, the device to be measured 2 is a television set or a video tape recorder, and in the case of a TV set, it may be somewhat difficult to extract the video signal if there is no output terminal for the video signal. In such a case, it can be easily taken out by providing a branch path between the video signal output terminal and the video signal input terminal of the TV station used as a monitor.

On the other hand, the channel measuring device 3 includes a tuner 4 that is connected to the receiving antenna 1 and receives television broadcasts independently of the bag to be measured W2, and a synchronization signal from the video signal demodulated by the tuner 4 to analyze the GCR signal. A timing detection circuit 5 that detects the arriving timing (described later), a sample hold circuit 6 that samples and holds the value of the video signal obtained from the device under test 2 according to the detection timing of the timing detection circuit 5, and A control/judgment unit that determines whether or not the output follows a predetermined sequence, changes the receiving channel of the tuner 4 if the output does not follow a predetermined sequence, and controls the timing detection circuit 5.
CPU) 7.

Figure 2 shows the waveform of the GCR signal inserted into the video signal of the broadcast wave, and within the period sandwiched by the horizontal synchronization signal a, the change in sin χ/X A flat portion C at a level of 70% is provided. Note that d is a color burst. By the way, on the TV Cent side, the GC was actually transformed with the addition of a ghost.
A filter is configured to receive the R signal, compare it with a reference waveform, and cancel its ghost.

Further, the GCR signal is inserted into line 18H and line 281H within the vertical retrace period, and furthermore, as shown in FIG. 3, is sent out in an 8-field sequence. This is to facilitate detection of the GCR signal on the receiving side. Therefore, when monitoring line 18H and line 281H, the GC
“1” indicates that there is an R signal, and “1” indicates that there is no GCR signal.
0'', the following signal sequence is obtained.

The operation of the embodiment shown in FIG. 1 will be explained below.

First, it is assumed that the device 2 to be measured, such as a television set or a video tape recorder, is receiving a television broadcast on one of the channels.

On the other hand, the tuner 4 of the channel measuring device 3 receives the television broadcast on the channel instructed by the control/judgment section 7 independently of the device to be measured 2, and provides the demodulated video signal to the timing detection circuit 5.

The timing detection circuit 5 detects the timing at which the GCR signal is inserted from the video signal demodulated by the tuner 4, that is, the line 18H and the line 281H. A signal with a timing that allows sampling is given to the sample and hold circuit 6.

The sample and hold circuit 6 samples the value of the video signal acquired from the device to be measured 2 using the timing signal provided from the timing detection circuit 5, and provides the held value to the control/determination section 7. Note that the values to be sampled are
It may be a binary value indicating whether or not there is a GCR signal.

The control/determination unit 7 determines whether the value of the sample and hold circuit 6 satisfies the 8-field sequence, and changes the channel of the tuner 4 if the value is not satisfied even after monitoring for a predetermined period of time.

That is, since each broadcast station broadcasts using its own synchronization signal and the GCR signal is sent out according to a predetermined sequence, the tuner 4 is connected to the same channel as the device under measurement 2.
Unless a channel is received, it is highly unlikely that the sampled values will return in the predetermined sequence, ie, .

Therefore, by varying the receiving channel until the sampled values are found to follow a predetermined sequence, and continuing this for all receivable channels, we get:
The channel that has stopped changing can be determined to be the receiving channel of the device to be measured.

In exceptional cases, when multiple broadcasting stations use the same synchronization signal (for example, NHK's general television and educational television), it is not possible to identify each one using only the configuration of the above embodiment. However, in this case, identification can be made by further determining whether the GCR signals match in time. That is, the GCR signal generator is generally provided independently from the synchronization signal system equipment for each broadcasting station, and the start positions of the 8-field sequences of the GCR signals almost never match.

In this case, in addition to the configuration of the embodiment shown in FIG. 1, a sample and hold circuit is newly provided to sample the video signal of the tuner 4 using the timing signal of the timing detection circuit 5, and the held value is transferred to the control/judgment section. give to 7;
The control/determination section 7 may determine whether the signal provided from the sample and hold circuit 6 matches the signal provided from the newly provided sample and hold circuit.

〔Effect of the invention〕

As explained above, in the channel measurement method of the present invention, it is determined whether the result of sampling the video signal of the device to be measured according to a predetermined timing follows a certain sequence of GCR signals, and if the result is positive. Channel measurement can be performed by simply changing the channel until , so the device can be realized with a simple configuration and stable operation can be achieved without requiring delicate adjustments.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a channel measuring device to which the channel measuring method of the present invention is applied, and FIG. 2 is a GCR
The signal waveform diagram and FIG. 3 are explanatory diagrams of the transmission sequence of the GCR signal. In the figure, 1... Receiving antenna 2... Device to be measured 3... Channel measuring device 4... Tuner 5... Timing detection circuit 6...Sample hold circuit

Claims (1)

[Claims] Receive a television broadcast and obtain a video signal independently of the device to be measured, detect the timing at which a GCR signal is inserted from this video signal, and detect the video signal obtained from the device to be measured. channel measurement, characterized in that the receiving channel is sampled at the specified timing, the receiving channel is varied until the sampled values are recognized to follow a predetermined sequence, and the channel that stops changing is determined to be the receiving channel of the device to be measured. Method.