JPH04185079A - Waveform equalizer - Google Patents

Abstract

PURPOSE:To perform waveform equalization and high-speed characteristic switching while utilizing many transversal filters not utilized other than ghost elimination by switching the connection of plural transversal filters serially, groupingly, and parallely. CONSTITUTION:At the time of the ghost elimination while connecting plural transversal filters (TF) serially, for example, switches 31 to 33 are turned on output signals 21 to 23 sides. At this point, an input signal 11 becomes an output signal 24 while passing through TF1 to TF4. When switching switches 31 to 33 so as to be divided into some groups, the waveform equalization of a complicated transmission system such as a Y/C independent transmission system of VTR can be performed. Then, at the time of parallel connection, high-speed characteristic change can be performed. Thus, the waveform equalization of plural transmission systems and high-speed characteristic switching or the like can be performed by utilizing many TFs which is not used other than the ghost elimination.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a waveform equalization device in a system that performs ghost removal and waveform equalization using a transversal filter.

(Prior Art) Conventionally, there is a ghost clean television tuner as a device equipped with a waveform equalization device.

In Clear Vision, which began broadcasting in October 1990, ghost cancellation reference signals (hereinafter referred to as OCR) are inserted in 18H and 281H.

First, a conventional technique for performing ghost cancellation and waveform equalization on the receiving side using this OCR will be explained with reference to FIGS. 6 to 8.

The OCR standard is as shown in Fig. 6 (a) for signal A (OCR waveform) and Fig. 6 (b) for signal B (pedestal waveform).
) is the 8-field sequence A, B, A, B, B.
, A, B, A are inserted in this order.

The following description will be made based on the block diagram of the ghost cancellation system shown in FIG.

In the figure, the human power waveform Xk, the output waveform Yk, the reference waveform Rk, and the error waveform Ek are sample value series. The input waveform Xk and the output waveform Yk are the difference signal A between the four fields of the TF input signal.
-B is a differential signal of the absolute value and has a 5inX/X waveform.

The TF input signal is input to an input terminal 51 and sent to a transversal filter 52 (hereinafter referred to as TF52) and a four-field difference signal device 53a. The TF52 performs waveform equalization on the input TF input signal using a separately input tap gain coefficient, and outputs the TF output signal to the output terminals 61 and 4.
It is output to the field difference signal device jt53b. 4 field differential signal system! 153a is 4 of the input TF input signal.
A differentiator 54 calculates the absolute value of the difference signal A-B between the fields.
Output to a. The differentiator 54a differentiates the absolute value of the difference signal A-B between the four fields of the TF input signal and outputs the input waveform Xk to the ghost detector 57. The 4-field difference signal device 53b converts the absolute value of the difference signal A-B between the 4 fields of the input TF output signal into a differentiator 54b.
Output to. The differentiator al'54b differentiates the absolute value of the difference signal AB between the four fields of the TF output signal, and outputs the output waveform Yk to the subtracter 56. The output Rk from the reference signal source 55 is input to a subtracter 56. The subtractor 56 to which the output waveform Yk and the reference signal source 55 are inputted, outputs the output waveform Y
An error waveform E which is the difference between k and the output Rk of the reference signal source 55
k is output to the ghost detection device 57. The ghost detection device 57, which receives the error waveform Ek and the input waveform Xk, outputs the calculated data to the tap gain coefficient correction device 58. The tap gain coefficient correction device 58 to which the calculated data has been input exchanges the tap gain coefficient with the tap gain coefficient memory 59.
Rewrite the old tap gain coefficient with the new tap gain coefficient. The tap gain coefficient memory 59 in which the new tap gain coefficient has been written is stored in the tap gain coefficient writing device! ! The tap gain coefficient is output to 60. Tap gain coefficient writing device 6 into which the tap gain coefficient is input
0 can write the tap gain coefficient of the TF 52 and change the characteristics of the TF 52.

Ghost removal and waveform equalization are performed as described above.

The time required to change the characteristics at this time is the time required to update the tap gain coefficient of the TF, and is proportional to the number of taps of the TF, and the larger the number of taps, the longer the time required.

Also, as a countermeasure for screen disturbance when rewriting tap gain coefficients,
The tap gain coefficient is rewritten within the vertical blanking interval so that it does not appear on the screen.

Also, since TF52 usually does not have many taps per piece, multiple TFs are connected in series as shown in Figure 118, and the TFI is mainly used for waveform equalization, and the remaining TFs are used for ghost removal. It is used for.

The system described above is configured for the purpose of ghost removal and waveform equalization, and when there is a mode in which only waveform equalization is desired, TF2 to TF4 in Fig. 8 are wasted, and the remaining TF is Not available. Further, even when used as a variable characteristic filter, it requires time to rewrite the tap gain coefficient, and there are problems such as the impossibility of instantaneous switching of characteristics.

(Problem to be Solved by the Invention) In this way, in the conventional device, ghost removal using multiple TFs connected in series produces unnecessary TFs that are not used when used only as a characteristic variable filter. Ta. Furthermore, even when used as a variable characteristic filter, it was not possible to instantly switch the characteristic because it required time to rewrite the tap gain coefficient.

The present invention aims to eliminate the drawbacks of the prior art as described above and to effectively utilize TF for various purposes.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides first and second input terminals into which signals to be equalized are input, and a first transversal filter to which a signal from an input end is input; a second transversal filter;
tap gain coefficient writing means for writing first and second tap gain coefficients into the first and second transversal filters, respectively; an output signal from the first transversal filter; and a second input terminal. and switching means for selectively switching the signal from the first transversal filter and supplying the signal to the second transversal filter, and the switching means supplies the output signal from the first transversal filter to the second transversal filter. , obtain the signal from the second transversal filter,
When the signal from the second input terminal is supplied to the second transversal filter by the switching means, output signals from the first transversal filter and the second transversal filter are obtained. There is.

(Function) When removing ghosts and equalizing waveforms, multiple TFs are connected in series, but in a mode configured in this way, the TFs used are
Since the number of signals required is small, it is possible to divide the waveform into several sets and use them to perform waveform equalization corresponding to a plurality of transmission systems. Furthermore, by switching the outputs of a plurality of TFs connected in parallel, the characteristics can be changed instantaneously.

As described above, TF can be used effectively.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 5.

The input signal 11 is input to the terminal 101 in FIG.
Sent to I. TF1 to which the input signal 11 is input performs waveform equalization using the tap gain coefficient written by the tap gain coefficient writing device 6, and outputs the output signal 21 to the output terminal 105 and the switching device 31.

Input signal 12 is input to terminal 102 and sent to switching device 31 . The switching device 31 to which the output signal 21 of the TFI and the input signal 12 from the terminal 102 are input selects either signal according to the signal from the control device 7 and switches the TFI to the input signal 12 from the terminal 102.
Output to 2. The TF2 to which the signal from the switching device 31 is input performs waveform equalization using the tap gain coefficient written by the tap gain coefficient writing device 6.
Output signal 22 is output to output terminal 106 and switching device 32 .

The input signal 13 is input to the terminal 103 and sent to the switching device 32 . TF2 output signal 22 and input terminal 10
The switching device 32 to which the input signal 13 from the control device 7 is input selects one of the signals according to the signal from the control device 7 and outputs it to the TF3.

The TF 3 to which the signal from the switching device 32 is input performs waveform equalization using the tap gain coefficient written by the tap gain coefficient writing device 6, and outputs the output signal 23 to the output terminal 107 and the switching device 33.

The input signal 14 is input to the terminal 104 and sent to the switching device 33 . TF3 output signal 23 and input terminal 10
The switching device 33 to which the input signal 14 from the control device 7 is input selects one of the signals according to the signal from the control device 7 and outputs it to the TF4.

The TF 4 to which the signal from the switching device 33 is manually applied performs waveform equalization using the tap gain coefficient written by the tap gain coefficient writing device 6, and outputs the output signal 24 to the output terminal 108.

The tap gain coefficient calculation device 5 to which the external signal is input outputs the tap gain coefficient to the tap gain coefficient writing device 6. The tap gain coefficient writing device 6 to which the tap gain coefficients have been input writes the respective tap gain coefficients to each of the transversal filters TF1 to TF4.

There are various connection methods for devices connected in this way, and four connection methods will be explained below.

First Connection Method Below, the second connection method will be explained with reference to FIGS. 1 and 3.

In the case of series connection, the switches 31 to 33 are connected to the TF output signals 21 to 23, respectively, and the input signal 11 passes through the TFIs to 4 and becomes the output signal 24. This is used when a large number of taps are required for the purpose of ghost removal as shown in FIG. That is, the second
In the figure, the human power signal 11 is an on-air composite signal,
The tap gain coefficient writing device 6 writes the tap gain coefficients output from the tap gain coefficient calculation device 5 into TF1 to TF4, performs ghost removal, and obtains an output signal 22.

Second Connection Method The second connection method will be explained below with reference to FIGS. 1 and 3.

When the switch 32 shown in FIG. 1 is turned on the input signal 13 side and the other switches are turned on the TF output side of each previous stage, the signal paths are divided into two systems and output as shown in FIG. 3. This is a VTR
This is used when only two systems of waveform equalization are performed, such as for the purpose of waveform equalization of the reproduced signal of a video image. That is, input signal 1
1.13 are the reproduced luminance signal and the reproduced color signal, and the waveform equalization corresponding to each transmission system is performed as TF1, 2 and TF1, respectively.
Perform at F3.4. Here, we used two stages of TF,
If there is a sufficient number of taps, a TFL stage may be used.

Moreover, it may be three or more stages.

Third Connection Method The third connection method will be explained with reference to FIGS. 1 and 4.

In FIG. 1, all switches 31 to 33 are connected to the input signal 12.
-14 side and input signals 11-14 are all the same signal, TFI-4 will be connected in parallel. Then, as shown in FIG. 4, the detection device 37 is connected to the input signal 15 and TF1-4
An addition is added between the switches 34 for selecting the output signal of the output signal.

The characteristics of TF1 to TF4 are set to different characteristics, and the input signal 15 is
The switch 34 selects the input signal and outputs the output signal 25 based on the signal from the detection device 37 that detects the type of the signal.

In this case, since the TF to be used is simply switched, switching can be performed faster than changing the characteristics by rewriting the tap gain coefficient, and instantaneous switching is possible. With this, switching is possible even during video signals.

Fourth Connection Method The fourth connection method will be explained below with reference to FIGS. 1 and 5.

The second connection method and the third connection method may be combined to form a configuration as shown in FIG. 5.

In the il1 diagram, all switches 31 to 33 are connected to input signal 1.
When input signals 11.12 and 13.14 are input to the 2 to 14 sides and the input signals 11.12 and 13.14 are the same signal, TFI, 2 and TF3.4 are connected in parallel, respectively. As shown in FIG. 5, a detection device 38 for detecting the type of input signal is connected to the input signal 16 and
Detection device to detect the type of input signal between! 39 is added between the input signal 17 and the switch 36. And T
The switch 35 for selecting the output signal of F1゜2 is
A switch 36 for selecting the 3.4 output signal is also added. The function is the same as the third connection method with two systems.

This makes it possible to instantaneously switch between the two systems of waveform equalization.

[Effects of the Invention] According to the present invention, when a plurality of TFs are connected in series, a sufficient number of taps for ghost removal can be obtained, and when divided into several groups, the Y of a VTR can be Waveform equalization compatible with complex transmission systems such as /C independent transmission systems can be performed, and when connected in parallel, characteristics can be quickly varied.

This makes it possible to perform waveform equalization and high-speed characteristic switching of a plurality of transmission systems by using a large number of TFs, which have not been used for anything other than ghost removal in the past.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the waveform equalization device of the present invention. FIG. 2 is a block diagram showing a connection example of the waveform equalizer of the present invention. FIG. 3 is a block diagram showing a connection example of the waveform equalizer of the present invention. FIG. 4 is a block diagram showing a connection example of the waveform equalizer of the present invention. FIG. 5 is a block diagram showing a connection example of the waveform equalizer of the invention. FIG. 6 is a block diagram showing a connection example of a waveform equalization device. FIG. 6 is a waveform diagram of a ghost cancellation reference signal. FIG. 7 is a block diagram showing a conventional waveform equalization device. FIG. FIG. 1 is a block diagram showing a conventional waveform equalization device.

Claims (1)

[Claims] First and second input terminals to which signals to be equalized are input; a first transversal filter to which signals from the first input terminal are input; and a second transversal filter. a versatile filter; tap gain coefficient writing means for writing first and second tap gain coefficients into the first and second transversal filters, respectively; an output signal from the first transversal filter; switching means for selectively switching the signal from the second input terminal and supplying the signal to the second transversal filter; When the signal from the second input terminal is supplied to the second transversal filter by the switching means, the signal from the second transversal filter is obtained. A waveform equalization device characterized in that output signals are obtained from a first transversal filter and a second transversal filter.