JPH09284607A - Waveform equalizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the malfunction of a waveform equalizing processing, which is caused by the phase change of a quantization clock. SOLUTION: A waveform equalizing device is provided with a transversal filter 102 processing the waveform equalization of an input TV signal which is quantized by a quantizing means 101, a waveform memory 103 taking-out and storing a waveform equalizing reference signal, a waveform equalizing control means 104 operating waveform equalization from the waveform equalizing reference signal stored in the waveform memory 103 and controlling equalization through the use of the transversal filter 102 and a quantization clock phase change detecting means 120 detecting the phase change of the quantization clock from the waveform equalizing reference signal stored in the waveform memory 103. Then, when the phase change of the quantization clock is detected, the waveform equalizing processing is interrupted.

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 equalizing the waveform of signal distortion generated during transmission in EDTV broadcasting and high-definition broadcasting.

[0002]

2. Description of the Related Art Hi-vision broadcasting and EDTV (Exte
Neded Definition Tele Visi
on) In television signal transmission such as broadcasting, the waveform equalization technique is an effective technique for removing transmission distortion and reproducing a high-definition image.

As an example of the waveform equalizer, an academic report of the Television Society (1989), Vol. 13, No. 3
2, pp. There is a "GCR compatible ghost canceller" reported in 31-36. This is a ghost elimination reference signal GCR (Ghost Cancel Re) which makes a loop in eight fields superimposed in the vertical blanking period of the EDTV signal.
ference) signal (hereinafter referred to as GCR reference signal)
To perform a correlation calculation with a signal having an ideal characteristic of the GCR reference signal on the time axis (hereinafter referred to as an ideal GCR reference signal) to sequentially correct the tap coefficient of the transversal filter to perform waveform equalization. Is.

The operation of the conventional waveform equalizer will be described below with reference to the drawings. FIG. 4 is a block diagram showing an example of the configuration of a conventional waveform equalizer that uses a ghost canceller of the EDTV signal system as an example.

In FIG. 4, 100 is an input terminal for an EDTV signal, 110 is a clock generating means for generating a quantized clock, and 101 is an A / D for quantizing the input EDTV signal.
A converter, 102 is a transversal filter, 103 is a waveform memory for taking in the GCR reference signal superimposed on the input EDTV signal, and 104 is a CPU for performing waveform equalization calculation processing from the GCR reference signal.

[0006] The EDTV system configured as described above,
The operation of the conventional waveform equalizer will be described below.

In FIG. 4, EDTV signal input terminal 1
One of the EDTV signals input from 00 is supplied to the A / D converter 101, and the other is supplied to the clock generation means 110. The clock generation means 110 generates a quantized clock based on the synchronizing signal of the input EDTV signal, and A /
It is supplied to the D converter 101.

A / D converter 101 is clock generation means 1
Input terminal 1 using the quantized clock supplied from 10
The EDTV signal input from 00 is quantized and output to the transversal filter 102. In the initial state of waveform equalization, the tap coefficient of the transversal filter 102 is set so that the input signal is output as it is.

The reference signal GCR signal for waveform equalization superimposed on the EDTV signal is a transversal filter 1
The output signal of 02 is taken into the waveform memory 103 and then inputted to the CPU 104.

The GCR reference signal of the EDTV system is shown in FIG.
The WRB signal shown in (a) and the 0 pedestal signal shown in FIG. 5 (b) are WRB signal → 0 pedestal signal → WRB signal → 0 pedestal signal → 0 pedestal signal → WRB signal → 0 pedestal signal → WRB for each field. The signals are superposed in the same horizontal period so as to form a signal, and the sequence is one cycle of eight fields.

By performing the operation shown in the first equation on the signals of these eight fields, the color burst signal and the signal from which the horizontal synchronizing signal component is removed, as shown in FIG. 5C, can be obtained. it can.

F = 1/4 {(F1-F5) + (F6-F2) + (F3-F7) + (F8-F4)} (Formula 1) However, in Formula 1, Fn (n = 1 to 8: n is an integer)
Represents the signal of the n-th field.

Hereinafter, the processing between fields as shown in the first equation is called field sequence processing.

The CPU 104 further differentiates the signal shown in FIG.
A signal waveform as shown in (d) is obtained. This waveform serves as a reference signal for waveform equalization processing.

FIGS. 7A and 7B are detailed views of the impulse portion of FIG. 5D. Normally, the clock generating means 11
0 operates so as to quantize the positions of the ◯ mark and the X mark in FIG.

Next, the CPU 104 compares the waveform shown in FIG. 5 (d) obtained by the field sequence processing and the differential processing with an ideal GCR reference signal (hereinafter referred to as an ideal GCR reference signal), and The tap coefficient of the transversal filter 102 is calculated from the error to control the coefficient of the transversal filter 102.

Generally, as a method for obtaining the tap coefficient of a transversal filter, for example, ZF (Zero Fo) is used.
rcing) method. In this method, the optimum tap coefficient is finally obtained by sequentially correcting it on the time axis according to a certain algorithm.

Output E of transversal filter 102
GCR reference signal and ideal GC superimposed on DTV signal
Assuming that the error signal sequence with the R reference signal is {Ek} and the total number of taps is M, the nth tap coefficient {Ci} (n) of the transversal filter is calculated based on the second equation below in the ZF method.

However, α is a coefficient for determining the correction amount. {Ci} (n + 1) = {Ci} (n) -α · Ek [i = 0, M-1] (second equation) The CPU 104 causes the GCR loaded in the waveform memory 103
After the S / N is improved by synchronously adding to the reference signal a sufficient number of times to remove the noise component, the field sequence process of the first equation and the operation of the second equation are performed to calculate the tap coefficient, and the transformer is calculated. Set in the Versal filter 102.

The series of processes are performed by software, and the flowchart is shown in FIG. In this process,
GCR reference signal and ideal G captured by waveform memory 103
The process is repeated until the amount of error from the CR reference signal becomes sufficiently small.

[0021]

In the conventional EDTV-type waveform equalizer, ghost detection may not be normally performed when the phase of the quantization clock changes during waveform equalization processing, for example. For example, at the time when the waveform equalization processing is started, even if the quantized clock for quantizing the position of FIG. 7A is generated, the clock generation means is affected by flutter interference or the like, as shown in FIG. 7B. There are cases where different positions are quantized. That is, a completely different ghost is detected as shown in FIGS. 7 (a) and 7 (b). This leads to a malfunction of the waveform equalization process.

[0022]

SUMMARY OF THE INVENTION To solve the above-mentioned problems, a waveform equalizing apparatus of the present invention uses a reference signal for waveform equalization superimposed on a quantized input television signal to obtain a quantized clock. The phase change is detected, and the waveform equalization method is changed according to the phase change amount.

The present invention can realize a stable waveform equalizer by the above method.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A waveform equalizer according to the present invention detects a phase change of a quantization clock from a reference signal for waveform equalization superimposed on a quantized input television signal, and determines the phase change amount. The waveform equalizer is characterized by changing the waveform equalization method according to the method, and enables a stable waveform equalization operation even if the phase of the quantization clock changes due to flutter interference or the like.

Next, the waveform equalizer of the present invention comprises a clock generating means for generating a quantized clock by using a synchronizing signal of an input television signal on which a waveform equalizing reference signal is superimposed, and the clock generating means. Quantizing means for quantizing the input television signal by using a quantizing clock output from, a transversal filter for performing waveform equalization processing of the input television signal quantized by the quantizing means, A waveform memory for extracting and storing the reference signal for waveform equalization from the television signal output from the transversal filter, and the transversal filter for performing waveform equalization operation from the reference signal for waveform equalization stored in the waveform memory. Waveform equalization control means for performing waveform equalization control by using a waveform equalization reference signal stored in the waveform memory. 2. The waveform according to claim 1, further comprising: a quantization clock phase detecting means for detecting a phase change of the quantization clock, wherein the waveform equalization processing is interrupted when the phase change of the quantization clock is detected. It is an equalizer, and when the quantization clock temporarily changes, it is possible to prevent the malfunction of the waveform equalization process by interrupting the waveform equalization.

Also, the waveform equalizer of the present invention determines whether the phase change of the quantization clock detected by the quantization clock phase detection means is temporary or continuous. Equipped with phase change state determination means,
The feature is that the waveform equalization process is interrupted when the phase change of the quantization clock is temporary, and the waveform equalization process is restarted from the beginning when the phase change of the quantization clock is continuous. The waveform equalizer according to claim 1, wherein when the quantization clock is stable in a changed state,
By repeating the waveform equalization process from the beginning, it is possible to prevent malfunction of the waveform equalization process.

(Embodiment 1) FIG. 1 shows an example of the configuration of the waveform equalizer of the present invention. In FIG.
Is an input terminal of the EDTV signal, 110 is a clock generating means for generating a quantization clock based on the synchronizing signal of the EDTV signal input from the input terminal 100, 101 is an A / D converter for quantizing the input EDTV signal, Reference numeral 102 is a transversal filter, 103 is a waveform memory for capturing a GCR reference signal superimposed on an input EDTV signal, 120
Is a clock phase detecting means for detecting the phase of the quantization clock from the GCR reference signal fetched by the waveform memory 103. Reference numeral 104 denotes a CPU that performs waveform equalization calculation processing from the GCR reference signal.

FIG. 2 is a flow chart showing the flow of processing of the waveform equalizer of this configuration example. Hereinafter, FIGS. 1 and 2
The operation will be described with reference to FIG.

In FIG. 1, EDTV signal input terminal 1
The EDTV signal input from 00 is supplied to the A / D converter 101 on the one hand and the clock generating means 110 on the other hand. The clock generation means 110 generates a quantized clock based on the synchronizing signal of the input EDTV signal and supplies it to the A / D converter 101.

A / D converter 101 is clock generation means 1
The EDTV signal input from the input terminal 100 is quantized by the quantization clock supplied from 10 and output to the transversal filter 102. In the initial state of waveform equalization, the tap coefficient of the transversal filter 102 is set so that the input signal is output as it is.

The reference signal GCR signal for waveform equalization superimposed on the EDTV signal is the transversal filter 1
The output signal of 02 is taken into the waveform memory 103, one of which is the CPU 104 and the other is the clock phase detecting means 120.
Is input to

The clock phase detecting means 120 detects the phase of the quantized clock from the GCR reference signal input from the waveform memory 103 and outputs the detection result to the CPU 104.

As described in the conventional example, the CPU 104 subjects the GCR reference signal input from the waveform memory 103 to the field sequence processing and the differential processing of the first equation, and the waveform equalization processing shown in FIG. 5 (d). To obtain the reference signal of. After that, when the detection result of the quantized clock phase input from the clock phase detection means 120 has not changed from the previous waveform equalization processing, the CPU 104 ideally performs the GCR signal subjected to the field sequence processing and the differential processing, and the ideal. GCR
The reference signals are compared, the tap coefficient of the transversal filter 102 is calculated from the error, and the coefficient of the transversal filter 102 is controlled. If the result of detection of the quantized clock phase has changed since the previous waveform equalization processing, the subsequent processing is interrupted and the GCR reference signal is fetched again.

In this process, the process is repeated until the amount of error between the GCR reference signal captured by the waveform memory 103 and the ideal GCR reference signal becomes sufficiently small.

As described above, according to the present invention, when the resample phase detected by the clock phase detecting means 120 has changed from the previous waveform equalization processing, the waveform equalization processing is interrupted and the GCR signal is read again. As a result, it is possible to prevent malfunction of the waveform equalization processing.

(Embodiment 2) FIG. 3 is a flow chart showing another processing flow of the waveform equalizer of the present invention. The operation will be described below with reference to FIGS. 1 and 3.

In FIG. 1, EDTV signal input terminal 1
One of the EDTV signals input from 00 is supplied to the A / D converter 101, and the other is supplied to the clock generation means 110. The clock generation means 110 generates a quantized clock based on the synchronizing signal of the input EDTV signal and supplies it to the A / D converter 101.

The A / D converter 101 is a clock generating means 1
The EDTV signal input from the input terminal 100 is quantized by the quantization clock supplied from 10 and output to the transversal filter 102. In the initial state of waveform equalization, the tap coefficient of the transversal filter 102 is set so that the input signal is output as it is.

The GCR reference signal for waveform equalization superimposed on the EDTV signal is a transversal filter 102.
Is taken into the waveform memory 103, one is inputted to the CPU 104 and the other is inputted to the clock phase detecting means 120.

The clock phase detecting means 120 detects the phase of the quantized clock from the GCR reference signal input from the waveform memory 103 and outputs the detection result to the CPU 104. The CPU 104 uses the waveform memory 1 as described in the conventional example.
The GCR reference signal input from H.03 is subjected to the field sequence processing and differentiation processing of the first equation, and FIG.
A reference signal for waveform equalization processing shown in is obtained. After this CP
U104 is a GCR signal which has been subjected to field sequence processing and differential processing and an ideal GCR when the detection result of the quantized clock phase input from the resample phase detection means 120 has not changed from the previous waveform equalization processing. The transversal filter 1
The tap coefficient of 02 is calculated and the transversal filter 1
Control the coefficient of 02.

The CPU 104 also has a function as a phase change state judging means. That is, CPU1
If the detection result of the quantized clock phase has changed since the previous waveform equalization processing, 04 determines whether the quantized clock phase change is temporary or continuous, and If it is a normal one, interrupt the waveform equalization process and
The CR reference signal is captured again. Then, when the phase change of the quantization clock is continuous, that is, when the phase of the quantization clock changes and is stable at the changed phase, the waveform equalization process is restarted from the beginning.

As a method for judging whether the phase change of the quantization clock is temporary or continuous, for example, the phase detection result of the quantization clock at the last five GCR fetches is saved and saved. If all the detected results are the same, it is determined that they are continuous, and if not, it is determined that they are temporary phase changes of the quantization clock. The subsequent processing is interrupted and the GCR reference signal is read again.
In this process, the process is repeated until the amount of error between the GCR reference signal captured by the waveform memory 103 and the ideal GCR reference signal becomes sufficiently small.

As described above, according to the present invention, it is judged whether the phase change of the quantized clock detected by the clock phase detecting means 120 is temporary or continuous, and the phase change is temporary. If the waveform equalization process is interrupted, G
The CR reference signal is captured again. If the quantization clock phase changes continuously, that is, if the quantization clock phase changes and is stable at the changed phase, the waveform equalization process is restarted from the beginning. Can be prevented from malfunctioning.

In the present embodiment, the phase change state judging means is software processing by the CPU, but it may be constituted by hardware.

[0045]

As described above, according to the present invention, the phase change of the quantization clock is detected from the waveform equalization reference signal superimposed on the quantized input television signal, and the phase change amount is detected according to the phase change amount. Since the waveform equalization method is changed by the above method, it is possible to prevent the malfunction of the waveform equalization processing caused by the phase change of the quantization clock, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of a waveform equalizer according to an embodiment of the present invention.

FIG. 2 is a diagram showing a flowchart of the operation of the waveform equalizer in one embodiment of the present invention.

FIG. 3 is a diagram showing a flowchart of the operation of the waveform equalizer according to another embodiment of the present invention.

FIG. 4 is a block diagram of a conventional waveform equalizer.

FIG. 5 is a GCR signal waveform diagram of a conventional waveform equalizer.

FIG. 6 is a diagram showing a flowchart of processing of a conventional waveform equalizer.

FIG. 7 is a GCR signal waveform diagram of a conventional waveform equalizer.

[Explanation of symbols]

 100 input terminal 101 A / D converter 102 transversal filter 103 waveform memory 104 CPU 109 output terminal 110 clock generation means 120 clock phase detection means

Claims (3)

[Claims] 1. A method of detecting a phase change of a quantization clock from a waveform equalization reference signal superimposed on a quantized input television signal and changing a waveform equalization method according to the amount of phase change. A characteristic waveform equalizer. 2. A clock generating means for generating a quantized clock using a synchronizing signal of an input television signal on which a reference signal for waveform equalization is superimposed, and a quantized clock output from the clock generating means. From the signal output from the transversal filter, and a quantizer that quantizes the input television signal, a transversal filter that performs waveform equalization processing of the input television signal quantized by the quantizer. A waveform memory that retrieves and stores the waveform equalization reference signal, and a waveform that performs waveform equalization control from the waveform equalization reference signal stored in the waveform memory and performs waveform equalization control using the transversal filter. And a phase change of the quantization clock from the waveform equalization reference signal stored in the waveform memory. A waveform equalizer, comprising: quantization clock phase detection means, wherein the waveform equalization processing is interrupted when a phase change of the quantization clock is detected by the quantization clock phase detection means. 3. Quantum clock phase detecting means is provided with phase change state judging means for judging whether the phase change of the quantized clock is temporary or continuous, When the phase change of the quantization clock is temporary, the waveform equalization process is interrupted, and when the phase change of the quantization clock is continuous, the waveform equalization process is restarted from the beginning. Item 2. The waveform equalizer according to item 2.