JPH0468975A - Television signal processing unit - Google Patents

Abstract

PURPOSE:To obtain a reproduced picture subjected to distortion compensation even during initial equalization adjustment feedback state by operating a 1st equalization means based on a test signal so as to calculate an optimum tap coefficient of a transversal filter and setting the coefficient to a coefficient multiplier of a 2nd equalization means. CONSTITUTION:The unit is provided with a 2nd equalization means 23b to a video signal in addition to a 1st equalization means 23A to a test signal. The accuracy in an equalization output by the equalization means 23B may be more deteriorated than that in an equalizing output by a test signal and since the reproduction picture is compensated by the equalization output by the video signal for an adjustment period, a reproduced picture with some degree of quality is obtained. When a tap coefficient by the test signal is obtained, the tap coefficient is set to the equalization means 23B and then the equalization is implemented by using the tap coefficient obtained accurately. Thus, distortion is accurately compensated even for the equalization adjustment period.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a television signal processing device, and particularly to a television signal processing device.

MUSE in the TV receiver 11 of a high-definition television (HDTV) system.
This invention relates to a decoder for a TV receiver, such as a Sampling Encoding decoder.

[Conventional technology]

The MUSE method is a kind of sample value transmission method, in which the samples of the input image signal are rearranged and transmitted as analog sample values (Nikkei Electronics, 19B7, 1).
1, 2. (No. 433), see page 192).

Transmission distortion results in interference between sample values, resulting in ringing on the playback screen. In order to remove this ringing, it is considered effective to provide a waveform equalizer in the MUSE decoder to perform waveform equalization. An example of the configuration of this MUSE decoder is shown in FIG.
MUSE decoder built-in waveform equalizer J, 1988 Television Society National Conference, 16-6, pages 351-35
2, see).

The MUSE decoder in FIG. 8 includes a low-pass filter 11.
Clamp circuit 12. A/D converter 13, delay circuit 1
4. Banfa Ambient using FET16. A/D converter 17. Waveform equalizer with built-in transversal filter 18. Subsample switch 19. Adjustment on/off switch 20° addition circuit 15. V T included in the received signal
T (Vertical Interval Te5
t) It is composed of a circuit 21 for extracting pulses and a microcomputer 22 as shown in the figure. The delay circuit 14 is A/
The output of the D converter 13 is delayed to match the timing with the signal from the waveform equalizer 18.

The distortion to be equalized by the MUSE decoder varies greatly depending on variations in tuners, differences in input characteristics such as Devio disks, transmission systems, and signal distribution systems. Therefore, the waveform equalizer 18 is used to compensate for the distortion components. The sub-sample switch 19 applies the equalization signal from the waveform equalization filter 18 to the main line signal at the VIT pulse reception timing, and causes the addition circuit 15 to compensate for distortion. Also.

The adjustment on/off switch 20 is closed during the adjustment period using the VIT pulse.

A microcomputer (μC) 22 cancels distortion in the transmission system based on the reference impulse response multiplexed in the vertical blanking of the MUSE signal based on the VIT pulse signal extracted by the VIT pulse extraction circuit 21. Next, the tap coefficients of the waveform equalizer 18 are determined, and the tap coefficients are set in the coefficient multiplication circuit within the waveform equalizer.

Since the transmission rate of the MUSE method is 16.2 MH2, the sampling frequency (sampling rate) of the single-line A/D converter 13 is 16°2 MH2.On the other hand, in principle, in order to perform waveform equalization, Sampling frequency at least twice the transmission rate, 32.4M) 12
The sampling frequency of the A/D converter 17 and waveform equalizer 18 of the sub line system is 32.4 MH.
It is 2.

[Problem to be solved by the invention]

The conventional MUSE decoder described above has the following problems.

Even once equalization adjustment is completed, readjustment is often necessary due to changes in the characteristics of the transmission system. However, conventional systems have not been configured to automatically perform equalization adjustment, and I can not cope.

Even if you try to automatically readjust by operating the adjustment on/off switch 2o, in the conventional circuit configuration, when the adjustment on/off switch 2o is turned off (open), the equalized output will be 1. is cut off, and the output of the adder circuit 15 is all (
The received image signal remains unequalized and contains distortion, and a reproduced image in which ringing occurs is displayed during the equalization adjustment period.

The equalization adjustment time varies greatly depending on the state of distortion. For example, 6-equalization adjustment, which can be completed in about 30 seconds and can take several minutes, requires repeating VIT pulses to obtain the tap coefficients. If the adjustment on/off switch 20 is left on, there is a problem in that the user is forced to continue viewing the image being adjusted during this adjustment period.

The above-mentioned problem is not limited to MUSE decoders.

A similar problem occurs when distortion compensation is performed in other TV receivers.

In view of the above, the present invention provides a television signal processing device capable of online equalization adjustment while providing a reproduced image of a certain level of quality even during the equalization adjustment period, and more specifically,
The purpose of this invention is to provide a decoder for a TV receiver.

The present invention also relates to a television signal processing device that automatically readjusts according to changes in distortion characteristics, and more specifically, to a television signal processing device that automatically readjusts according to changes in distortion characteristics.
The purpose is to provide a decoder for a television receiver.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a television signal processing device that equalizes waveform distortion of a received signal. a transversal filter type waveform equalization means having equalization means of 2 and energized during the adjustment period;
switching means for outputting the output of the first or second equalization means in response to a test signal reception period and a video signal reception period; and a switching means for operating the first equalization means based on the test signal to perform transversal processing. and control means for calculating an optimal tap coefficient of the filter and setting it in a coefficient multiplier of the second equalization means.

Preferably, the control means energizes the switching means when the equalization characteristic of the first equalization means falls below a predetermined value, adjusts the tap coefficient based on the test signal, and adjusts the tap coefficient to the optimum value. When the tap coefficient is obtained, the tap coefficient of the second equalization means is updated with the tap coefficient, and the switching means is deenergized.

[Effect]

The television signal processing device of the present invention includes, in addition to a first equalization means for a test signal equivalent to the conventional one, a second equalization means for a video signal. Although the equalized output may be less accurate than the equalized output from the test signal, the reproduced image is compensated by the equalized output for this video signal even during the adjustment period, so it is possible to provide a reproduced image with a certain level of quality. . Once the tap coefficients based on the test signal are obtained, the tap coefficients are set in the second equalization means, and thereafter, equalization is performed using the accurately determined tap coefficients to accurately compensate for distortion.

Further, the control means automatically performs equalization adjustment in response to fluctuations in distortion characteristics.

〔Example〕

As an embodiment of the television signal processing device of the present invention, H
The case where it is applied to a MUSE decoder in a DTV TV receiver will be described with reference to FIG.
Elements that are the same as those in the conventional configuration described with reference to the drawings are designated by the same reference numerals, and therefore their description will be omitted.

In comparison with the configuration shown in FIG. 8, the MUSE decoder of the TV receiver shown in FIG. 1 includes a waveform equalization circuit 23. A mode switching circuit 24 as a switching means and a control microcomputer (μC) 24 as a control means are provided.

Waveform equalization circuit 23 in FIG. A first configuration example of the mode switching circuit 24 and the control μC 25 is shown in FIG.

The waveform equalization circuit 23 is configured by connecting a video signal waveform equalizer 23A as a first equalization means and a VIT pulse signal waveform equalizer 23B as a second equalization means in parallel. There is. The VIT pulse signal corresponds to the test signal. The video signal waveform equalizer 23A, as shown in FIG.
It consists of a transposed transversal filter. That is, this transversal filter 23A includes unit delay elements 101 to 105 . coefficient multipliers 111 to 115,
This is a transversal filter with multiple taps, for example, 5 taps, in which adder circuits 121 to 125 are connected in series. Tap coefficient kA1 of coefficient multipliers 111 to 116
~ kA6 is the adjustment period, control μC25, as described later.
Accordingly, the video signal waveform equalizer 23A and the control μC 25 constitute an adaptive transversal filter. The VIT pulse signal waveform equalizer 23B is also a transposed transversal filter having a similar circuit configuration, and its tap coefficients kB1-kB6 are also updated from the control μC 25. A received signal sampled by the A/D converter 17 is input to the waveform equalizer 23A and the waveform equalizer 23B.

FIG. 4 shows the transmission signal form of the MUSE signal.

As is clear from Fig. 4, the VITS period (hereinafter referred to as ■ period) in which VIT pulses are inserted and the video period (
(hereinafter referred to as P period).

The operation of the circuit shown in FIG. 2 will be described with reference to FIG. To initialize the unit time delay element, etc. (FIG. 5(b)), the mode switching circuit 24 is energized and during the adjustment period, the equalized output of the video signal waveform equalizer 23A in the P period is changed to VIT in the V period. The equalized output of the pulse signal waveform equalizer 23B is selectively outputted from the mode switching circuit 24 (FIG. 5(c)), and the video signal waveform equalizer 23A performs equalization processing during the P period. ,V
The IT pulse signal waveform equalizer 23B performs equalization processing during the P period. These equalization adjustment operations will be described later.

The mode switching circuit 24 outputs the video signal waveform equalizer 23A and the VIT pulse signal waveform equalizer 2 until predetermined equalization characteristics are obtained in the VIT pulse signal waveform equalizer 23B.
The equalized output of 3B is alternately applied to the adder circuit 15 corresponding to the P period and the V period, and even during the 2 equalization adjustment period, the reproduced image is distorted and compensated by the equalization result of the video signal waveform equalizer 23A. Ru. Although the equalized output of the video signal waveform equalizer 23A is often in a rough equalized state, it is possible to provide a reproduced image whose distortion has been compensated to some extent even during the 9 equalization adjustment period.

At time t2, the VIT pulse signal waveform equalizer 23B
When the equalization characteristic of reaches a predetermined value.

The control μC 25 has its VIT pulse signal waveform equalizer 23
The tap coefficient obtained in step B is set in the coefficient multiplier of the video signal waveform equalizer 23A. Then, at the third time point t3, the 9 control μC 25 deenergizes the mode switching circuit 24,
After that, the mode switching circuit 24 is fixed in the A contact state in which only the equalized output of the video signal waveform equalizer 23A is output. Therefore, once a predetermined equalization characteristic is obtained for the VJT pulse signal by the VrT pulse signal waveform equalizer 23B, the video signal is equalized based on the equalization characteristic, and the received signal is distortion is compensated for.

After that, the control μC 25 monitors the equalization state in the lrT pulse signal waveform equalizer 23B, and if the equalization characteristic, specifically the error described below, falls below a predetermined value, the mode switching circuit 24 is added. Then adjust the equalization again.

In this case, the following method can be selected as the operation mode of the video signal waveform equalizer 23A. The first method is to cause the video signal waveform equalizer 23A to perform an equalization operation together with the VIT pulse signal waveform equalizer 23B, as described above. Second
In the method, the tap coefficient of the video signal waveform equalizer 23A is V
The previously set values are maintained until the tap coefficients obtained by the IT pulse signal waveform equalizer 23B are updated. The third method is the above 2 depending on the distortion characteristics.
The idea is to selectively adopt two methods.

In the present invention, either method can be applied.

In either case, a distortion-compensated reproduced image will be displayed during this readjustment period.

The adjustment of the video signal waveform equalizer 23A and the VIT pulse signal waveform equalizer 23B is performed by updating the tap coefficients of these coefficient multipliers through repeated calculations so that the control μC 25 minimizes the error. . below,
An algorithm for equalization adjustment based on the VIT pulse signal will be described (see paper 16-5, 1988 Prevision Society National Convention, cited above).

The control μC 25 is the VrT pulse extraction circuit 2 in FIG.
Calculate the error between the VIT pulse from 1 and the ideal impulse response and the tap coefficient.

The tap coefficient is H(nT), (where n is an integer,
T is the time interval of sampling frequency 32.4MH2),
The transmission characteristic is F(nT) and the ideal impulse response is I(n
T), and the received sequence is Y(nT), then the received sequence Y
(nT) is represented by the following formula.

Y(nT) = [I(nT) Ning F(nT)
] + [I(nT) *F(nT) *
H(nT)] ・ ・ ・ (1) However, * is the convolution H(nT) = F ''(nT) ・ δ(nT)
...(2) However, if n=o, δ(nT)・1°, and other cases, δ(nT)・0.

When the process is performed, the tap coefficient old (nT) at that time is expressed by the following formula.

Old(nT) = I(-nT)) P(-nT)
Y(nT) = r(nT)...
-(3) and equalization is completed. Since the amplitude characteristics are not equalized, equalization is performed repeatedly at each VIT timing. This repeated correction is performed by the VIT pulse extraction circuit 21.
This is done by correcting the tap coefficient at that time using the error between the VIT pulse inputted to the control μC 25 and the ideal impulse response. i-th tap coefficient H+ (n
The reception sequence for T) is given by the following equation.

Old(nT) *I(nT) *F(nT) +I(nT)
*F(nT)-I(nT) 10Ei(nT) ・ ・ ・ ・ (4) However, Ei (nT) is the error. Repeat this process one after another so that this error Ei (nT) becomes smaller, and then Tap coefficient H+ (nT) at repetition step i = tap coefficient kB1~kB
6 and error E1 are calculated.

Below 1. The above-mentioned calculation is repeated until this error becomes less than a predetermined value, and the tap coefficients kB1 to kB6 of the VIT pulse signal waveform equalizer 23B are updated.

At the initial adjustment stage, the tap coefficients kA1-kA6 of the coefficient multiplier of the video signal waveform equalizer 23A are controlled by the control μC2.
5 is updated in the same manner as above, and VIT
As described above, when the error of the pulse signal waveform equalizer 23B becomes less than a predetermined value, the tap coefficients kA1 to kA6 of the coefficient multiplier of the video signal waveform equalizer 23A are replaced with the tap coefficients kB1 to kB6. .

FIG. 6 shows a second configuration example of the waveform equalization circuit 23. Second
The waveform equalization circuit 23 in the figure includes different video signal waveform equalizers 23A and VI as first and second equalization means, respectively.
Although a T-pulse signal waveform equalizer 23B is provided, the waveform equalization circuit 23 of FIG. 6 shares one transversal filter as the first and second equalization means, and tap coefficients kA1 to kA6 and The tap coefficients kB1 to kB6 are sent to the coefficient multiplier 111 via switching circuits 131 to 136.
to 115 can be selectively set. The tap coefficients kA1 to kA6 and the tap coefficients kB1 to kB6 are set from the control μC 25 as described above. The switching circuits 131 to 136 are the mode switching circuit 24 described above.
works the same way.

Since the waveform equalization circuit 23 of FIG. 6 requires only one expensive transversal filter, the cost can be reduced compared to the circuit configuration shown in FIG. 2.

The waveform equalization circuit 23 is not limited to the transversal filter circuit configuration shown in FIG. 3 and FIG. The figure shows a circuit diagram of a transversal filter having a circuit configuration different from that of the transposed transversal filter described above.

In the above description, as one embodiment of the television signal processing device of the present invention, M of a TV receiver of an HDTV system is described.
Although the USE decoder has been illustrated, one aspect of the present invention is the MUSE decoder.
The present invention is not limited to decoders, but can also be applied to other television signal processing devices that perform equalization adjustment.

〔Effect of the invention〕

As described above, according to the television signal processing apparatus of the present invention, a reproduced image whose distortion has been compensated to some extent can be provided even during the initial equalization adjustment period.

Further, according to the television signal processing device of the present invention, the equalization characteristic can be automatically adjusted according to fluctuations in the distortion characteristic, so that appropriate equalization can be performed according to the distortion state. In this case, the reproduced image can be provided with distortion compensation of considerably high quality due to the already obtained equalization characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a decoder of a TV receiver as an embodiment of the television signal processing device of the present invention. FIG. 2 is a block diagram of a first example of the waveform equalization circuit of FIG. 1. 2 is a circuit diagram of a transversal filter as a first example constituting the waveform equalization circuit of FIG. 2, and FIG. 4 is a signal transmission form diagram of a MUSE signal. Figure 5 shows the control microcomputer shown in Figure 2;
Adjustment operation timing diagram of the video signal waveform equalizer, VIT pulse signal waveform equalizer, and mode switching circuit; FIG. 6 is a diagram showing another configuration example of the waveform equalization circuit of FIG. 2; FIG. 7 8 is a diagram showing another configuration example of a transversal filter as a waveform equalizer in an embodiment of the present invention.
The figure is a block diagram of a conventional MUSE decoder. (Explanation of symbols) 13, 1 19 ・ ・ 21 ・ ・ 23 ・ ・ 23A ・ 23B ・ 24 ・ ・ 25 ・ ・ ...A/D converter. Subsampling switch. VIT pulse extraction circuit. Waveform equalization circuit. Video signal waveform equalizer VIT pulse signal waveform equalizer. Mode switching circuit. Control microcomputer.

Claims (1)

[Claims] 1. A television signal processing device that equalizes waveform distortion of a received signal, comprising a first equalization means and a first equalization means that equalizes a test signal and a video signal included in the received signal. a transversal filter type waveform equalization means having two equalization means, and the output of the first or second equalization means is energized during the adjustment period and responsive to the test signal reception period and the video signal reception period; a switching means for outputting, and a control means for operating the first equalization means based on the test signal to calculate an optimal tap coefficient of the transversal filter and setting it in a coefficient multiplier of the second equalization means. A television signal processing device comprising: 2. The control means energizes the switching means when the equalization characteristic in the first equalization means falls below a predetermined value, adjusts the tap coefficient based on the test signal, and adjusts the tap coefficient to an optimal tap coefficient. 2. The television signal processing apparatus according to claim 1, wherein when the second equalizing means is obtained, the tap coefficient of the second equalizing means is updated with the tapped coefficient to deactivate the switching means.