JPH0686097A - Waveform equalization device, television receiver, converter, waveform equalization system, television reception system, and video recording / reproducing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a waveform equalizer that can perform optimal waveform equalization processing even when receiving cable television broadcasting. [Constitution] When receiving the cable television broadcast, when changing the received contents, the converter 304 selects a channel. The converter 304 outputs a new program from the programs so far according to this tuning information. At this time, since the channel changes, signal discontinuity occurs at the output of the converter 304. The discontinuity detection circuit 102 detects this discontinuity and outputs a discontinuity detection signal. The waveform equalization circuit 104 is initialized by the input of the discontinuity detection signal, and the audio multiplex demodulation circuit 110 mutes the audio signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform equalizer for receiving cable television (CATV) broadcast and performing waveform equalization.

[0002]

2. Description of the Related Art With the start of Clear Vision broadcasting in 1989, a reference signal (GCR) for ghost elimination is inserted during the vertical blanking period of most terrestrial television broadcasting, and this GCR signal is used. As a result, ghosts can be removed with high precision and waveform equalization processing can be performed.

FIG. 2 shows a specific example of a waveform equalization circuit for performing such waveform equalization processing. In FIG. 2, 201 is a composite video signal input terminal, 205 is an A / D converter, and 20
3, 206 are addition circuits, 204, 207 are transversal filters, 233 are D / A converters, 222 is an integration circuit, 223 is a difference circuit, 209 is a reference signal generation circuit, 2
Reference numeral 08 is a comparison circuit, 210 is a tap coefficient circuit, 211 is a storage circuit, 230 is a control circuit, 216 is a waveform equalization output terminal, and 217 is a waveform equalization circuit.

FIG. 3 is a block diagram showing a specific example of the transversal filter shown in FIG. In FIG. 3, 252 is a signal input terminal, 253 is a delay element, and 2 is a delay element.
54 is a multiplier, 255 is an adder, and 256 is a signal output terminal.

Transversal filters 204 and 207
Has many pairs of delay elements and multipliers arranged at its output, that is, a large number of taps, and it is possible to realize an arbitrary frequency characteristic by controlling the tap gains of these.

The reference signal for ghost removal is a signal inserted into 18H and 281H once in one field.
SIN with a rising differential waveform of 4.2 MHz frequency band
The SIN (X) / X bar waveform having a response of (X) / X and the waveform of only the black level are signals which are repeated in a cycle of 8 fields. The signals sequentially transmitted in this manner are converted into Si (i
= 1 to 8), S ₁ -S ₂ + S ₃ -S ₄ -at the receiving side.
By processing the 8-field sequence of S ₅ + S ₆ −S ₇ + S ₈ , it becomes possible to detect the ghost signal without being disturbed by the horizontal sync signal, the color burst signal, and the signal contents of the previous line. .

The operation of the block diagram of FIG. 2 will now be described. The composite video signal input to the composite video signal input terminal 201 is converted into a digital signal by the A / D converter 205 and sent to the transversal filter 204 and the addition circuit 203. At the start of operation, the tap gains of the transversal filters 204 and 207 are set to zero. The output of the adder circuit 206 is sent to the integrator circuit 222, and the 8 field sequence process is performed to perform the integration. Then by differentiating the integration result,
Obtain the impulse waveform of the input signal. By comparing this with an ideal impulse waveform prepared in advance, an error due to distortion can be obtained.

To eliminate this error, the tap gains of the transversal filters 204 and 207 may be set in accordance with the distortion, and the tap coefficient circuit 210 and the control circuit 2 may be set.
30 using the transversal filters 204 and 20
When the tap gain of 7 is controlled, a signal with suppressed distortion can be obtained at the output of the addition circuit 206. The above is the operation of the conventional waveform equalization circuit.

By the way, in recent years, in addition to terrestrial broadcasting, a cable television (CATV) that services a large number of channels
Broadcasting is widespread. FIG. 4 shows a device connection example of a system for receiving the cable television broadcast and performing waveform equalization.

In FIG. 4, 301 is an antenna and 302 is
Is a cable television broadcasting station, 303 is a cable, 304 is a converter, 305 is a television receiver, 306 is a channel selection / video intermediate frequency amplification / detection circuit, 217 is a waveform equalization circuit, 1
Reference numeral 05 is a video processing circuit, and 106 is a picture tube.

In addition to transmitting its own program, the cable television broadcasting station 302 temporarily receives radio waves from existing terrestrial broadcasting stations, satellite broadcasting stations, etc., and serves as one program of the same cable television. As a result, the cable television broadcast receiver can view the terrestrial broadcast and the satellite broadcast by only receiving the cable television broadcast. In the cable television broadcast, not only free programs but also pay programs are broadcast, and the cable television broadcasting station 302 scrambles the programs so that only the contractor can view the pay programs.

The device for descrambling is converter 304. Converter 304 output is channel 2
The signal is a signal modulated into a signal and is connected to the television receiver 305. The cable television broadcast receiver is the television receiver 305.
While setting the receiving channel of 2 to 2,
A desired program is received by switching the receiving channel on the side.

An example of such a waveform equalizing circuit is disclosed in Japanese Patent Application Laid-Open No. 1-309508. Further, as an example of scrambling used for cable television broadcasting, Japanese Patent Laid-Open No. 4-15048 is known.
Examples thereof include those described in JP-A-8.

[0014]

When the cable television broadcast is received by the above-mentioned conventional technique, there are the following problems.

The first problem is that when the television receiver 305 performs waveform equalization processing such as ghost removal, the equalization processing may not be performed correctly. As described above, this is because the converter 304 side tunes in when receiving cable television broadcasts, so that the television receiver 305 side does not have switching information due to channel selection, and the conventional waveform equalization circuit 217 is input. Because it doesn't always follow changes. That is, the conventional waveform equalization circuit 217
In order to stabilize the waveform equalization operation, control is performed to stop the waveform equalization operation after the end of a predetermined operation or the passage of time. Therefore, even if the channel is switched by the converter 304, if the change in the received waveform distortion is below a certain level, new waveform equalization processing is not performed,
On the contrary, there was a problem of adding a ghost.

The second problem is that a switching sound is generated when the channel is switched by the converter 304. This problem is, after all, TV receiver 3
This is because the switching sound at the time of channel switching cannot be muted because there is no channel switching information on the 05 side.

A third problem is that in a waveform equalization circuit that stores information on waveform equalization processing and equalizes the waveform based on the information when tuning, the processing becomes unstable when a cable television broadcast is received. The problem is that it does not work as intended. In the conventional waveform equalization circuit 217, in order to speed up the waveform equalization process, the waveform equalization information of the previous waveform equalization is stored in the storage circuit 211, and the next time the waveform equalization process is performed, the waveform equalization information is stored. The waveform equalization information is read from the storage circuit 211 to shorten the processing time.
However, when receiving a cable television broadcast, since the channel switching information is not transmitted to the waveform equalization circuit 217, waveform equalization processing using waveform equalization information of different channels is performed. In such a case, There have been cases where the waveform equalization process takes a long time, or optimal waveform equalization is not performed.

An object of the present invention is to solve the above-mentioned problems and to provide a waveform equalizer which can perform optimum waveform equalization processing even when a cable television broadcast is received.

[0019]

In order to achieve the above object, in the present invention, a waveform equalizer for waveform equalizing a video signal arbitrarily selected from a plurality of videos, and a discontinuity of the video signal. A detection means for detecting, a delay means for delaying an audio signal corresponding to the video signal, and an attenuating means,
The waveform equalizer is initialized by the detection output of the detector, and the signal level of the output of the delay unit is attenuated or made zero in the attenuator.

Further, in order to achieve the above-mentioned object, the present invention has a waveform equalization information storage means capable of prohibiting the use of the contents of the waveform equalization information for each channel.

[0021]

The above-mentioned detecting means for detecting the discontinuity of the video signal,
Discontinuities such as color burst signals, horizontal synchronizing signals, vertical synchronizing signals, and GCR signals of video signals are always detected.
On the other hand, when the cable TV receiver uses the converter to tune, the video signals before and after tuning are not synchronized, so the color burst signal, horizontal sync signal, and vertical The sync signal and GCR signal are temporarily discontinuous. Therefore, when the channel is selected, the detecting means detects the discontinuity.

When the detecting means detects discontinuity, the detection output of the detecting means is sent to the waveform equalizing means as a reset. With this signal, the waveform equalization processing means is initialized, and the waveform equalization processing calculation is performed from the beginning. On the other hand, when the detecting means detects continuity, no signal is sent to the waveform equalizing means. Therefore, in this case, the waveform equalizing means holds the state where the equalization processing operation is completed. As described above, since the waveform equalization operation is initialized by the channel selection on the converter side, it is possible to perform the optimum waveform equalization operation for each channel.

Further, regarding the switching sound, since the detection output of the detecting means controls the attenuating means, when the detecting means detects discontinuity due to channel selection on the converter side, a voice signal is output. Attenuate the signal. Therefore, no switching sound is produced. Further, since the delay means delays after extracting the audio signal by the extracting means, the timing at which the detecting means detects the discontinuity is not delayed from the timing at which the switching sound is mixed.

Further, when the cable television is received, the use of the waveform equalization information of the receiving channel is prohibited by the use prohibition setting of the storage means for storing the waveform equalization information.
Therefore, the waveform equalization process does not become unstable or oscillate.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention.

In FIG. 1, 301 is an antenna for receiving terrestrial broadcasting, 302 is a cable television broadcasting station, 3
03 is a cable, 304 is a converter that receives a television signal from the cable 303 and descrambles it, 3
Reference numeral 05 is a television receiver, 100 is a channel selection circuit, 101 is a video intermediate frequency amplification / detection circuit, and 102 is a video intermediate frequency amplification / detection circuit.
A discontinuity detection circuit for detecting discontinuity of the video signal output from the detection circuit 101, 103 a discontinuity detection signal line, 104 a waveform equalization circuit, 105 a video processing circuit, 106 a picture tube, 107 an audio intermediate frequency A conversion circuit, 108 is an FM detection circuit, 109 is a delay circuit, 110 is a voice multiplex demodulation circuit,
Reference numeral 111 is an amplifier circuit, and 112 is a speaker.

First, the operation of the block diagram of FIG. 1 will be described. The cable television broadcasting station 302 provides a terrestrial broadcasting program as well as its own broadcasting program. To this end, the antenna 301 in the cable television broadcasting station 302
After receiving the terrestrial broadcast by, the programs are frequency-multiplexed and transmitted on the cable 303. At each home, the converter 304 selects an arbitrary program from the programs on the cable 303. The converter 304 checks whether or not the selected program has a contract, and if the program is contracted, descrambles it, frequency-converts the selected program into a fixed channel, and then outputs it as an output of the converter 304. . The output of this converter 304 is input to the television receiver 305.

The television receiver 305 uses the tuning circuit 100 to convert the output of the converter 304 into an intermediate frequency.
Next, regarding video signals, video intermediate frequency amplification / detection circuit 1
Amplification and detection are performed by 01 to convert to a baseband composite video signal. Then, the waveform equalization circuit 104 performs waveform equalization so as to remove the distortion of the composite video signal. Further, after the luminance / chromaticity separation and the color demodulation are performed by the video processing circuit 105, they are converted into RGB signals.
Finally, the RGB signals are amplified and displayed on the picture tube 106.

On the other hand, for the audio signal, the audio intermediate frequency signal is converted by the audio intermediate frequency conversion circuit 107 into a beat signal of 4.5 MHz. This signal is detected by the FM detection circuit 108.
Then, the voice signal including the voice multiplexed signal is detected and output. After delaying this detected output by the delay circuit 109, the voice multiplex demodulation circuit 110 takes out multiple voices. Then, after the voice processing is performed according to the voice multiplex mode, it is amplified and drives the speaker 112.

The above is an explanation of the operation when the channel selection operation has already been performed. Here, the operation when selecting a channel will be described. When a cable television broadcast is being received, the converter 304 performs all channel selection for selecting a program. After descrambling the selected signal, the converter 304 fixes the channel (this embodiment describes the case where the channel is fixed to channel 2) and outputs the signal.
On the other hand, the television receiver side fixes the reception channel to channel 2 and receives the converter output 304. The viewer selects the channel of the converter 304 in order to change the received content of the cable television broadcast. The output of the converter 304 outputs a new program from the programs so far according to this tuning information. At this time, since the channel changes, signal discontinuity occurs at the output of the converter 304. The discontinuity detection circuit 102 detects this discontinuity and outputs it as a discontinuity detection signal to the waveform equalization circuit 103 and the audio multiplex demodulation circuit 110.

Here, a specific example of the discontinuity detection circuit 102 will be described in detail with reference to the drawings. FIG. 5 is a block diagram showing a first specific example of the discontinuity detection circuit in FIG.
In FIG. 5, 701 is a composite video signal input terminal, 702
Is a sync separation circuit, 703 is a detection circuit, 704 is a low-pass filter, 705 is an oscillation circuit, 706 is an amplification circuit, 70
Reference numeral 7 is a comparison circuit, and 708 is a discontinuity detection signal output terminal. Among them, the detection circuit 703 and the low pass filter 704
The oscillator circuit 705 constitutes a phase locked loop (PLL) circuit.

The output of the detection circuit 703 is the synchronization separation circuit 70.
It is the result of multiplication of the two outputs and the continuous internal horizontal synchronizing signal which is the output of the oscillation circuit 705. By guiding this result to the low pass filter 704, the output of the synchronizing separation circuit 702 which is the input and the inside of the television receiver. The phase error with the continuous horizontal synchronizing signal can be obtained as the output of the low pass filter 704. When the channel is not selected, the horizontal synchronizing signal maintains continuity, so that a phase error hardly occurs and the output of the low pass filter 704 does not change. On the other hand, at the time of tuning, the continuity of the horizontal synchronizing signal is broken, a phase error occurs, and an error signal appears at the output of the low pass filter 704. The signal level of this error signal is amplified by the amplifier circuit 706 and compared with a predetermined level to output the discontinuity detection signal to the discontinuity detection signal output terminal 707.
Can be obtained.

FIG. 6 is a block diagram showing a second specific example of the discontinuity detection circuit in FIG. In FIG. 6, 801 is a composite video signal input terminal, 802 is a burst extraction circuit, 803 is a detection circuit, 804 is a low pass filter, 805 is an oscillation circuit, 806 is an amplification circuit, 807 is a comparison circuit, and 808 is discontinuity detection. This is a signal output terminal. In the figure, the detection circuit 803, the low pass filter 804, and the oscillation circuit 805 form a PLL circuit.

The output of the detection circuit 803 shows the result of multiplication of the output of the burst extraction circuit 802 and the continuous color subcarrier signal which is the output of the oscillation circuit 805. By introducing this result to the low-pass filter 804, the phase error between the color burst signal of the composite video signal on the composite video signal input terminal 801 and the continuous color subcarrier inside is output to the low-pass filter 804. Can be obtained as Therefore, when the channel is not selected, the color burst signal maintains continuity, so there is almost no phase error,
There is no change in the output of the low pass filter 804. On the other hand, at the time of tuning, the continuity of the color burst signal is lost, a phase error occurs, and an error signal appears at the output of the low pass filter 804. It is possible to obtain the discontinuity detection signal at the discontinuity detection signal output terminal 808 by amplifying the signal level of this error signal by the amplifier circuit 806 and comparing it with a predetermined level.

FIG. 7 is a block diagram showing a third specific example of the discontinuity detection circuit in FIG.

In FIG. 7, 901 is a composite video signal input terminal, 902 is a burst extraction circuit, 903 is a detection circuit,
904 is a low-pass filter, 905 is an oscillation circuit, and 906
Is a 910 frequency divider circuit, 907 is an integration circuit, 908 is a sync separation circuit, 909 is a detection circuit, 910 is a low-pass filter, 911 is an oscillation circuit, 916 is a frequency divider circuit, 912 is an integration circuit, and 913 is a comparison circuit. , 914 is an integrating circuit, 91
Reference numeral 5 is a discontinuity detection signal output terminal. In Figure 7, two P
An LL circuit is configured.

One is a P including a detection circuit 903, a low-pass filter 904, an oscillation circuit 905, and a frequency division circuit 916.
LL circuit, which is locked to the color burst signal included in the composite video signal on the composite video signal input terminal 901.
The fsc clock signal is generated as the output of the oscillator circuit 905. The output of this oscillation circuit 905 is divided into a 910 frequency divider circuit 906.
To generate a pulse having a horizontal cycle, and further integrate by an integrating circuit 907 to obtain a signal in the vertical period.

The other PLL circuit is a detection circuit 909,
It is composed of a low-pass filter 910 and an oscillation circuit 911. A horizontal synchronizing signal is taken out from a composite video signal on a composite video signal input terminal 901 by a sync separation circuit 908, and a horizontal continuous signal is locked inside the horizontal sync signal. Play the sync signal. Then, the output of the oscillation circuit 911 which is the reproduced horizontal synchronizing signal is integrated by the integration circuit 912,
Obtain the signal for the vertical period.

The output of the integrating circuit 907 and the output of the integrating circuit 912 thus obtained are compared in phase by the comparing circuit 913 and further integrated by the integrating circuit 914 to detect the discontinuity at the discontinuity detection signal output terminal 915. Get the signal.

Furthermore, FIG. 8 is a block diagram showing a fourth specific example of the discontinuity detection circuit in FIG. In FIG. 8, reference numeral 1001 is a composite video signal input terminal, 1005 is a sync separation circuit, 1002 is a binarization circuit, 1003 is a microprocessor, and 1004 is a discontinuity detection signal output terminal.

The operation of FIG. 8 will be described with reference to FIG. Figure 9
FIG. 9 is a timing chart showing timings of main signals and the like in FIG.

First, the composite video signal from the composite video signal input terminal 1001 is synchronously separated by the sync separation circuit 1005. Then, the obtained sync separation signal is binarized by the binarization circuit 1002 for digital processing, and the binarized signal shown in FIG. 9A is obtained. The binarized signal is sampled by the microprocessor 1003 according to the sampling pulse shown in FIG. Then, since the period of the sync signal is low level and the video period is high level, discontinuity of the sync signal can be recognized by monitoring each level and time. That is, in the case of a continuous signal, the sync signal period and the video signal period repeat like A, B, A, and B as shown in FIG. 9C, but when discontinuity occurs, this relationship is broken. Therefore, the microprocessor 1003 determines whether or not this relationship is established.
By monitoring by, the discontinuity can be detected.

By the way, the sync signal includes a vertical sync signal and a horizontal sync signal. Since the discontinuity due to tuning exists for several field periods, it is possible to detect the discontinuity from the vertical sync signal. It is also possible to detect discontinuity from the sync signal. Similarly, even if the continuity of the reference signal for ghost removal is detected using the circuit of FIG.
It is possible to detect discontinuities.

Next, the waveform equalization circuit 104 in FIG. 1 will be described. FIG. 10 is a block diagram showing a specific example of the waveform equalization circuit in FIG. In FIG. 10, 11
Reference numeral 03 is a video signal input terminal, and 1104 is a waveform equalization circuit 10.
4 is an output terminal, 205 is an analog-digital conversion circuit,
203 and 206 are addition circuits, 204 and 207 are transversal filters, 222 is an integration circuit, 223 is a difference circuit, 209 is a reference signal generation circuit, 208 is a comparison circuit, 2
10 is a tap coefficient calculation circuit, 211 is a storage circuit, 230
Is a control circuit, 1101 is a memory circuit control signal input terminal, 1
102 is an initialization signal input terminal.

First, the configuration of the waveform equalization circuit 104 shown in FIG. 10 will be described. The waveform equalizer circuit 104 is roughly divided into two circuit blocks, and includes a waveform equalizer that actually performs the waveform equalization operation and a calculator that determines the filter characteristic of the waveform equalizer. The waveform equalization unit is configured by a cascade connection of a non-recursive filter at the front stage and a recursive filter at the rear stage.

The non-recursive filter in the preceding stage is the addition circuit 20.
3. The transversal filter 204 is a filter for removing distortion in the vicinity. The recursive filter in the latter stage is composed of an adder circuit 206 and a transversal filter 207, and is a filter for removing a ghost. Here, the transversal filters 204 and 207 are filters whose characteristics can be changed arbitrarily, and the changing method is performed by setting the value of the tap coefficient in the transversal filter. The details of this transversal filter are described in Japanese Patent Publication No. 1-59789.

The calculating section for determining the filter characteristic of the waveform equalizing section is a circuit for calculating the tap coefficient by an algorithm called the successive correction method. In the successive correction method, the tap coefficient is obtained by minimizing the error signal that is the difference between the output signal and the internal reference signal. The zero forcing method is known as an algorithm for minimizing this error signal.

Here, assuming that the input is X _k , the output of the waveform equalizer is Y _k , and the reference signal waveform is R _k , the error signal E _k between the output and the reference signal waveform is expressed by the equation 1.

[0049]

[Equation 1]

Further, the output Y _k can be expressed by Equation 2 when the tap coefficient of the transversal filter is C _i .

[0051]

[Equation 2]

The tap coefficient by the zero forcing method is
The operation of Equation 3 is repeatedly obtained.

[0053]

[Equation 3]

Next, the operation of the waveform equalization circuit 104 shown in FIG. 10 will be described. The discontinuity detection signal output from the discontinuity detection circuit 102 is the initialization signal input terminal 1
From 102, it is input to the waveform equalization circuit 104, and all tap coefficients stored in the tap coefficient circuit 210 are cleared. The cleared tap coefficient is set to the control circuit 230.
Is sent to the tap coefficients of the transversal filters 204 and 207. Then, the outputs of the transversal filters 204 and 207 become 0, and the video signal of the video signal input terminal 1103 appears at the output of the addition circuit 206 as it is. This video signal is integrated by the integration circuit 222,
Reduce the effects of noise. And this integration circuit 22
By subtracting the two outputs, the reference signal inserted in the video signal is extracted. The comparison circuit 2 compares the sent reference signal of the video signal with the output of the reference signal generation circuit 209.
The error signal is obtained by comparing with 08. Then, using this error signal, the tap coefficient for the first time is calculated by Equation 3, and stored in the tap coefficient circuit 210.

Next, the output of the tap coefficient circuit 210 is read by the control circuit 230 and written in the transversal filters 204 and 207. Then, if a video signal is taken in from the video signal input terminal 1103 in this state, the calculation result calculated by Equation 2 is obtained at the input of the integrating circuit 222. After integrating the obtained calculation result in the integrating circuit 222,
Differentiation is performed by the difference circuit 223 to obtain the second reference signal. The output of the difference circuit 223 and the output of the reference signal generation circuit 209 are compared by the comparison circuit 208 to obtain the error signal for the second time. Using this error signal, the second tap coefficient is obtained in the same manner as the first tap coefficient calculation.

Similarly, the tap coefficient is updated, and when the error signal falls below a predetermined level, the operation of the calculation section is ended. Then, the waveform equalization unit performs the waveform equalization operation using the tap coefficient value at the last convergence.

The above is the operation of the waveform equalization circuit 104. As can be seen from the above description, the video signal 1 is repeatedly output.
It takes time to input 103 and obtain a tap coefficient for integration by the integration circuit 222.

By the way, since the antenna for receiving terrestrial broadcasting is at a fixed location, the ghost situation varies from channel to channel, but it is considered that there is almost no temporal variation. Therefore, the tap coefficient after waveform equalization of each channel is almost constant for each channel. Utilizing this, the tap coefficient after waveform equalization is stored in advance in the storage circuit 211 for each channel, and the storage circuit 21
If the tap coefficient is calculated from the value using one output, the tap coefficient calculation operation time is significantly improved.

However, this can be said when the television receiver directly receives the terrestrial broadcast, and when the cable television broadcast is received, the channel of the television receiver remains fixed. In order to change the receiving channel through the converter, it is often the case that distortion is added to the change in the input distortion.

Therefore, the memory circuit control signal input terminal 110
1 is used to control each channel of the memory circuit 211. In the description of the present embodiment, the cable television broadcast is received on the fixed channel of channel 2. Therefore, when the converter is connected, as shown in FIG. Is stored and the output of the storage circuit 211 is invalidated. ON is stored in the other channel column so that it is valid.
In addition, as shown in FIG. 11, ON / OF is set for each channel.
F may be stored, but in order to simplify the circuit,
ON / OFF may be stored as the entire storage circuit 211. Even in this way, it is sufficient for the viewer who receives only the cable television broadcast.

By the way, although this ON / OFF storage may be performed manually, the reception state of the television receiver is a fixed channel for a long time by using a microprocessor, and the frequency of occurrence of the discontinuity detection signal. It is also possible to automatically switch to OFF by detecting that the value is high.

In the present embodiment, the sequential correction method is used as the calculation unit. However, as another calculation method, a method of division on the frequency axis (so-called division method) can be used for calculation. is there. The division method is described in Takashi Tanihagi: Theory of Digital Signal Processing, 2 Filters / Communications / Images, pp. 155 to 158.

The waveform equalization circuit 104 has been described above. Regarding the video signal, as shown in FIG. 1, the video processing circuit 105 thereafter performs luminance color separation and color demodulation, and then the RGB signal. Convert to. Finally, the video is amplified and displayed on the picture tube 106.

Next, the audio signal of the television receiver 305 when the channel selection operation is performed will be described. As shown in FIG. 1, also in this case, the audio intermediate frequency signal is converted by the audio intermediate frequency conversion circuit 107 into a beat signal of 4.5 MHz. Then, this signal is detected by the FM detection circuit 108, and the audio signal including the audio multiplexed signal is detected and output.
The output of the FM detection circuit 108 is delayed by the delay circuit 109 and then subjected to multiple voice processing by the voice multiplexing circuit 110.

Discontinuity detection signal 103 detected during channel selection
In the audio multiplexing circuit 110, the audio signal is greatly attenuated (generally called mute). The place where the audio signal is attenuated may be anywhere as long as it is possible to attenuate the audio signal, instead of the audio multiplexing circuit 110 shown in FIG. Further, the level of the audio signal may be set to 0 instead of attenuating the audio signal. After that, the output of the audio multiplexing circuit 110 is sent to the speaker 112 via the amplifier circuit 111, but since it is attenuated by the audio multiplexing circuit 110, no switching sound is output.

Also, since the audio signal is delayed by the delay circuit 109 for the time for detecting the discontinuity from the video signal, the switching sound does not occur for a moment due to the time required for the detection.

Here, the converter 304 will be supplementarily described. In order to make the detection by the discontinuity detection circuit 102 as described above more accurate, it can be considered that the discontinuous state is clearly output on the converter 304 side. For this purpose, the horizontal sync signal discontinuity, vertical sync signal discontinuity, color burst signal discontinuity, color burst signal presence / absence, GCR signal discontinuity, horizontal The discontinuous state may be generated by not satisfying the predetermined relationship between the sync signal and the color burst signal.

Next, FIG. 12 is a block diagram showing a second embodiment of the present invention. In FIG. 12, 301 is an antenna, 302 is a cable television broadcasting station, 303 is a cable, 304 is a converter, 305 is a television receiver, 10
0 is a channel selection circuit, 101 is a video intermediate frequency amplification / detection circuit,
Reference numeral 104 denotes a waveform equalizing circuit, 105 denotes a video processing circuit, 10
6 is a picture tube, 107 is an audio intermediate frequency conversion circuit, 108 is an FM detection circuit, 110 is an audio multiplex demodulation circuit, 111 is an amplification circuit, and 112 is a speaker.

The configuration of FIG. 12 is obtained by removing the portion for attenuating the sound from the configuration of FIG. 1, and the operation is the same as the processing of the video signal of FIG. In this way, the system is simple and proper waveform equalization processing can be realized. The switching sound can be reduced by maintaining the continuity of the voice carrier signal on the converter 304 side.

Next, FIG. 13 is a block diagram showing a third embodiment of the present invention. In FIG. 13, 301 is an antenna, 302 is a cable television broadcasting station, 303 is a cable, 304 is a converter, 305 is a television receiver, and 50.
1 is a switching information signal line, 502 is a converter output line,
100 is a channel selection circuit, 101 is an image intermediate frequency amplification / detection circuit, 104 is a waveform equalization circuit, 105 is a video processing circuit,
106 is a picture tube, 107 is an audio intermediate frequency conversion circuit, 10
8 is an FM detection circuit, 109 is a delay circuit, 110 is a voice multiplex demodulation circuit, 111 is an amplifier circuit, and 112 is a speaker.

In this embodiment, when the converter 304 selects a channel, the switching information is output to the switching information signal line 501. Then, on the television receiver 305 side, the switching information on the switching information signal line 501 is supplied to the waveform equalization circuit 104 to initialize the waveform equalization operation, and also supplied to the audio multiplexing circuit 110 to output the audio signal. Decay.

In this way, although the number of signal lines is increased by one, it is possible to more reliably initialize the waveform equalization circuit 104 and attenuate the audio signal. By the way, in the case of the present embodiment, the switching information can be created by the switching command from the viewer from the remote controller or the like without being detected from the discontinuity of the video signal, so that the delay circuit 1 is not always necessary.
It is not necessary to provide 09.

Next, FIG. 14 is a block diagram showing a fourth embodiment of the present invention. In FIG. 14, 301 is an antenna, 302 is a cable television broadcasting station, 303 is a cable, 600 is a converter, 601 is a channel selection / video intermediate frequency amplification circuit, 104 is a waveform equalization circuit, 602 is a decoder for descrambling, 603 Is a frequency conversion circuit, 60
Reference numeral 4 is an output line A, 604 is an output line B, and 605 and 606 are television receivers.

In this embodiment, the converter 600 includes a channel selection / video intermediate frequency amplification circuit 601 and a waveform equalization circuit 104.
Since it has, it is possible to update the waveform equalization processing each time a channel is selected. Further, since the mute processing is performed at the time of channel selection, it is possible to eliminate the switching sound.

Further, this signal is frequency-converted into a frequency in the channel 2 etc. by using the frequency conversion circuit 603 and output line A
After being output to 604, the television receiver 606 can receive a waveform-equalized image. Further, by outputting the output of the decoder 602 to the output line B605 and receiving this signal by the television receiver 607, it is possible to receive the video signal whose waveform is equalized.

Further, in this embodiment, the waveform equalizing circuit 104 is used.
The storage circuit 211 makes it possible to speed up the waveform equalization process. That is, if the tap coefficient after waveform equalization for each channel is stored in the storage circuit 211 and the tap coefficient is calculated from the value using the output of the storage circuit 211, the tap coefficient calculation operation is performed at high speed. Be converted. In this case, since the converter 600 directly receives the ground wave, the waveform equalization circuit 104 does not add distortion.

By the way, in the above description, the combination of the converter and the television receiver has been described, but a device such as a VTR which receives a television signal and converts and outputs it to a fixed channel, and a television receiver. The present invention can be applied to the combination with.

[0078]

As described above, according to the present invention, since the tuning operation can be detected, there is an effect that optimum waveform equalization can always be performed even when receiving a cable television broadcast. Further, since the audio signal is muted when the channel is selected, there is an effect that a switching sound is not generated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific example of a conventional waveform equalization circuit.

FIG. 3 is a block diagram showing a specific example of the transversal filter in FIG.

FIG. 4 is a block diagram showing an example of a conventional waveform equalization system.

5 is a block diagram showing a first specific example of the discontinuity detection circuit in FIG. 1. FIG.

FIG. 6 is a block diagram showing a second specific example of the discontinuity detection circuit in FIG.

7 is a block diagram showing a third specific example of the discontinuity detection circuit in FIG. 1. FIG.

8 is a block diagram showing a fourth specific example of the discontinuity detection circuit in FIG.

FIG. 9 is a timing chart showing the timing of main signals and the like in FIG.

10 is a block diagram showing a specific example of the waveform equalization circuit in FIG.

11 is an explanatory diagram for explaining contents stored in a memory circuit in FIG.

FIG. 12 is a block diagram showing a second embodiment of the present invention.

FIG. 13 is a block diagram showing a third embodiment of the present invention.

FIG. 14 is a block diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

301 ... Antenna, 302 ... Cable TV broadcasting station, 3
03 ... Cable, 304 ... Converter, 305 ... Television receiver, 100 ... Channel selection circuit, 101 ... Video intermediate frequency amplification / detection circuit, 102 ... Discontinuity detection circuit, 103 ... Discontinuity detection signal output terminal, 104 ... Waveform, etc. Signal processing circuit, 105 ... video processing circuit, 106 ... picture tube, 107 ... audio intermediate frequency conversion circuit, 108 ... FM detection circuit, 109 ... delay circuit,
110 ... Voice multiplex demodulation circuit, 111 ... Amplification circuit, 112
… Speaker.

Claims (24)

[Claims] 1. A waveform equalizer for equalizing a waveform of a video signal, and a detector for detecting a discontinuity of the video signal, wherein the waveform equalizer is initialized by a detection output of the detector. A waveform equalizer characterized in that 2. A waveform equalizer for waveform equalizing a video signal, a detector for detecting a discontinuity of the video signal, a delay unit for delaying an audio signal corresponding to the video signal, and an attenuator. A waveform equalizer, comprising: a detection output of the detection means to initialize the waveform equalization means; and the attenuation means to attenuate or zero the signal level of the output of the delay means. 3. A video signal input means for inputting a video signal, a selection information input means for inputting selection information indicating switching of the channel of the video signal, and a waveform of the video signal input from the video signal input means. A waveform equalizing means for equalizing, wherein the waveform equalizing means is initialized by the selection information input from the selection information inputting means. 4. A waveform equalizer for equalizing a waveform of a video signal, waveform equalization information for each channel of the video signal, and the stored waveform etc. each time the channel of the video signal is switched. A waveform equalization apparatus comprising: storage means for supplying corresponding waveform equalization information to the waveform equalization means, of the equalization information, wherein the waveform equalization from the storage means to the waveform equalization means is set by setting. A waveform equalizer characterized in that the supply of information can be prohibited for each channel. 5. A waveform equalizer for equalizing a waveform of a video signal, waveform equalization information for each channel of the video signal is stored, and the stored waveform or the like is stored every time the channel of the video signal is switched. A waveform equalization apparatus comprising: storage means for supplying corresponding waveform equalization information to the waveform equalization means, of the equalization information, wherein the waveform equalization from the storage means to the waveform equalization means is set by setting. A waveform equalizer characterized in that the supply of information can be prohibited. 6. A selecting means for selecting one image from a plurality of images, a waveform equalizing means for equalizing the output of the selecting means, and a detecting means for detecting discontinuity of the output of the selecting means. And an extracting means for extracting an audio signal from the output of the selecting means, a delay means for delaying the output of the extracting means, and an attenuating means, and the waveform equalizing means is provided by the detection output of the detecting means. A waveform equalizer, which initializes and at the same time attenuates or reduces the signal level of the output of the delay means to zero. 7. The waveform equalizer according to claim 1, 2 or 6, wherein the detection means is at least the presence or absence of a color burst signal, a horizontal sync signal discontinuity, a vertical sync signal discontinuity, and a GCR signal. The waveform equalizing device is provided with a means for detecting that there is no discontinuity of the signal or that there is no predetermined relationship between the horizontal synchronizing signal and the color burst signal. 8. A detecting means for detecting a discontinuity of a video signal, a delay means for delaying an audio signal corresponding to the video signal, and an attenuating means, and the attenuating means by a detection output of the detecting means. In the television receiver, the signal level of the output of the delay means is attenuated or made zero. 9. The television receiver according to claim 8, wherein the detecting means includes at least the presence or absence of a color burst signal, a horizontal sync signal discontinuity, a vertical sync signal discontinuity, a GCR signal discontinuity, or A television receiver comprising means for detecting that the horizontal sync signal and the color burst signal are not in a predetermined relationship. 10. A selection means for selecting one video from a plurality of videos, a discontinuity means, a video output means for outputting the output via the discontinuity means of the selection means as a video output, A control means for controlling the continuous means,
A converter characterized in that, when a selection is made by the selecting means, the control means causes the output of the selecting means to be temporarily discontinuous in the discontinuous means. 11. A selection means for selecting one picture from a plurality of pictures, a discontinuity means, an extraction means for extracting an audio signal from an output of the selection means, an attenuation means, and a selection means for the selection means. The selection means includes an external output means for outputting the output through the continuous means and the output through the attenuation means of the extraction means to the outside, and a control means for controlling the discontinuous means and the attenuation means, respectively. When the above is performed, the control means causes the output of the selecting means to be temporarily discontinuous in the discontinuous means, and the signal level of the output of the delay means to be attenuated or made zero in the attenuating means. Converter to do. 12. The converter according to claim 10, wherein the discontinuity means is the presence or absence of a color burst signal, the discontinuity of the color burst signal, the discontinuity of the horizontal sync signal, the discontinuity of the vertical sync signal, and the GCR. Signal discontinuity,
A converter characterized in that the output of the selecting means is discontinuous by not satisfying a predetermined relationship between the horizontal synchronizing signal and the color burst signal. 13. A selection means for selecting one video from a plurality of videos, a video output means for outputting an output of the selection means as a video output, and a selection information output means for outputting selection information. A converter characterized by that. 14. A selecting means for selecting one image from a plurality of images, a waveform equalizing means for equalizing the output of the selecting means, and an output of the waveform equalizing means for outputting as an image output. A converter comprising: a video output unit. 15. Selection means for selecting one video from a plurality of videos, waveform equalization means for equalizing the output of the selection means, and storage means for storing waveform equalization information for each channel. A video output means for outputting the output of the waveform equalization means as a video output, and the output of the storage means is supplied to the waveform equalization means each time an image is selected. 16. A selecting device for selecting one image from a plurality of images and an output of the selecting device are input.
Alternatively, the waveform equalization device according to the item 2 is included. 17. A waveform equalization system comprising the converter according to claim 13 and the waveform equalization device according to claim 3. 18. A selection device for selecting one image from a plurality of images and an output of the selection device.
And a television receiver described in 1 .. 19. A selection means for selecting one video from a plurality of videos, a discontinuity means, a video output means for outputting the output through the discontinuity means of the selection means as a video output, A control means for controlling the continuous means,
A video recording / reproducing apparatus characterized in that, when a selection is made by the selection means, the control means causes the output of the selection means to be temporarily discontinuous in the discontinuous means. 20. A selection means for selecting one video from a plurality of videos, a discontinuity means, an extraction means for extracting an audio signal from the output of the selection means, an attenuation means, and a non-selection means for the selection means. The selection means includes an external output means for outputting the output through the continuous means and the output through the attenuation means of the extraction means to the outside, and a control means for controlling the discontinuous means and the attenuation means, respectively. When the above is performed, the control means causes the output of the selecting means to be temporarily discontinuous in the discontinuous means, and the signal level of the output of the delay means to be attenuated or made zero in the attenuating means. Video recording / playback device. 21. The video recording / reproducing apparatus according to claim 19 or 20, wherein the detecting means includes at least the presence / absence of a color burst signal, discontinuity of the color burst signal, discontinuity of the horizontal synchronizing signal, and the vertical synchronizing signal. Discontinuous, G
A video recording / reproducing apparatus comprising means for detecting discontinuity of a CR signal or a non-predetermined relationship between a horizontal synchronizing signal and a color burst signal. 22. A selection means for selecting one of a plurality of videos, a video output means for outputting an output of the selection means as a video output, and a selection information output means for outputting selection information. A video recording / reproducing apparatus characterized by the above. 23. Selection means for selecting one of a plurality of videos, waveform equalization means for equalizing the output of the selection means, and output of the waveform equalization means as a video output. An image recording / reproducing apparatus comprising: an image output unit. 24. Selection means for selecting one picture from a plurality of pictures, waveform equalization means for equalizing the output of the selection means, and storage means for storing the waveform equalization information for each channel. A video output means for outputting the output of the waveform equalization means as a video output, and the output of the storage means is supplied to the waveform equalization means every time a video is selected. .