JPH07255002A - Two-dimensional waveform equalizer - Google Patents

Abstract

(57) [Abstract] [Purpose] In a quadrature modulation method in which a carrier having a quadrature relationship with a video carrier is modulated with another signal and combined with the video carrier modulated with the video signal for transmission, multiplexing after crosstalk removal is performed. The object is to remove the out-of-band signal included in the signal to reliably remove the ghost. [Structure] A ghost removing means 103 removes and outputs a ghost of a video signal. The TRF 104 generates a signal for removing the crosstalk of the multiplexed signal from the output of the ghost removing means 103. The adder 105 uses the multiplexed signal and TR
The removal signal output from F104 is input and the multiplexed signal with crosstalk removed is output. The FIR 106 inputs the output of the adder 105 and removes out-of-band components and proximity ghosts of the multiplexed signal. The IIR 107 inputs the multiplexed signal output from the FIR 106 and removes a normal ghost. The arithmetic means 108 receives the output of the IIR 107 and controls the TRF 104, FIR 106 and IIR 107.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for receiving and reproducing a signal obtained by multiplexing another signal on a current television broadcast signal, and more particularly to a two-dimensional waveform equalizer for removing crosstalk and ghost. is there.

[0002]

2. Description of the Related Art As a method of multiplexing another signal on a television signal, a carrier having an orthogonal relationship with a video carrier is modulated with a signal having other information, and is synthesized with a video carrier modulated with the video signal. A quadrature modulation method for transmitting is known.

[0003] However, this system is a study on waveform equalization in EDTV system, pp. 329 to 330, page 15-8, "Video carrier quadrature modulation EDTV system", published by the Institute of Television Engineers of Japan, in 1988. , The signal having different information (hereinafter, due to imbalance of filter characteristics between the transmitting side and the receiving side, deviation of detection of the receiver, ghost interference, etc.
Crosstalk occurs between a video signal and a signal that is to be multiplexed.

Therefore, a two-dimensional waveform equalizer for removing the crosstalk and the ghost is required.

[0005]

However, in the conventional two-dimensional waveform equalizer, when the signal bands of the video signal and the multiplex signal are different, the out-of-band component of the multiplex signal is sufficiently removed when crosstalk is removed. In some cases, the out-of-band component is not removed, or the out-of-band component is included in the removed signal, and the out-of-band component is newly added to the multiplexed signal.

As described above, when the ghost elimination is performed when the signal component outside the frequency band remains, it may oscillate. Further, there is a problem that a signal component outside the band is amplified and interference is increased even if it does not oscillate.

An object of the present invention is to solve the above problems and to provide a two-dimensional waveform equalizer that eliminates ghosts without oscillating.

[0008]

SUMMARY OF THE INVENTION The above object is to remove a ghost removing means for removing a ghost by inputting a video signal and an output of the ghost removing means for removing crosstalk of the video signal from the multiplex signal. A transversal filter for generating a removal signal, an input of the output of the transversal filter and a multiplexed signal, an adder for outputting a multiplexed signal with crosstalk removed, and an output of the adder, A non-recursive filter that removes proximity ghosts of multiple signals and removes out-of-band signal components,
A recursive filter that inputs the output of the non-recursive filter and removes a normal ghost of a multiplexed signal, a coefficient of the transversal filter, and a coefficient of the recursive filter,
This can be achieved by providing a computing unit that computes a tap coefficient having a characteristic of removing a proximity ghost given to the non-recursive filter and a characteristic of removing a signal component outside the band.

[0009]

The ghost removing means removes the ghost contained in the input video signal. The transversal filter is controlled by the calculating means and receives the ghost-removed video signal output from the ghost removing means, and generates a signal for removing a crosstalk component of the video signal included in the multiplex signal. To do. The adder inputs the multiplex signal and the crosstalk removal signal output from the transversal filter, and outputs the multiplex signal with crosstalk removed.

The non-recursive filter is controlled by the arithmetic means and inputs the multiplexed signal output from the adder,
While removing the proximity ghost included in the multiplex signal,
A signal component outside the band of the multiplexed signal is removed. The cyclic filter is controlled by the calculating means, receives the proximity ghost output from the non-cyclic filter and the multiplexed signal from which the out-of-band component is removed, and removes a normal ghost included in the multiplexed signal.

The calculating means inputs the multiplexed signal output from the cyclic filter, calculates a tap coefficient for removing crosstalk, and outputs the tap coefficient to the transversal filter. In addition, a tap coefficient that normally removes a ghost is calculated and output to the cyclic filter, and a tap coefficient that also has a characteristic of removing a signal component outside the band is calculated and output to a non-recursive filter while removing a proximity ghost. To do.

As described above, by calculating the tap coefficient so that the non-recursive filter also has the characteristic of removing the out-of-band component, no new means is added,
It is possible to remove out-of-band components and reliably remove ghosts.

[0013]

EXAMPLE FIG. 1 shows an example of the present invention. 101 is a video signal input terminal, 102 is a multiplex signal input terminal, 103 is a ghost removing means, 104, 1061, 1071 are transversal filters (hereinafter referred to as TRF), 10
5, 1062 and 1072 are adders, 106 is a non-recursive filter (hereinafter referred to as FIR), 107 is a recursive filter (hereinafter referred to as IIR), 108 is calculation means, 109
Is a multiple signal output terminal.

The video signal input from the video signal input terminal 101 is output after the ghost is removed by the ghost removing means 103. The ghost removing means 103 can be realized by a TRF and using a general algorithm such as the ZF method or the MSE method. TRF104 is
The multiple signal input terminal 102 is controlled by the arithmetic means 108.
A signal for removing crosstalk of the video signal included in the multiplexed signal input from is generated from the ghost-free video signal output from the ghost removing means 103.

The multiplexed signal input terminal 102 inputs the multiplexed signal and outputs it to the adder 105. The adder 105 adds the multiplex signal and the crosstalk removal signal output from the TRF 104, and outputs the multiplex signal from which the crosstalk of the video signal included in the multiplex signal is removed.

The FIR 106 is a non-recursive filter composed of a TRF 1061 and an adder 1062, and is controlled by the arithmetic means 108 to remove a removal signal for removing a signal component outside the band of the multiplexed signal and a proximity ghost at the TRF 1061. The generated signal is added by the adder 1062 with the removal signal, and the signal with the out-of-band signal component and the proximity ghost removed is output. The IIR 107 includes a TRF 1071 and an adder 1
072 is a recursive filter, which is controlled by the arithmetic means 108 to generate a removal signal for removing the normal ghost of the multiplex signal by the TRF 1071, and adder 1072.
At, the input signal and the removal signal are added, and the signal from which the ghost is removed is output. The multiple signal output terminal 109 is IIR
The multiplexed signal from which the ghost output by 107 is removed is output.

The calculating means 108 inputs the multiplexed signal output from the IIR 107, and calculates the tap coefficient for removing crosstalk and the tap coefficient for removing ghost using a general ZF method or MSE method algorithm. , And outputs a tap coefficient for removing crosstalk to the TRF 104, and outputs a tap coefficient for removing a normal ghost to the IIR.
Furthermore, a coefficient of a low-pass filter (hereinafter, referred to as an LPF) that removes frequency components outside the band is convolved with a tap coefficient that removes a proximity ghost, and a characteristic that removes a proximity ghost and an out-of-band signal component simultaneously. To the FIR 107.

As described above, by using the FIR coefficient as the convolution operation result of the LPF coefficient and the ghost removal coefficient, the ghost removal having the characteristic of removing the out-band signal component without separately providing the LPF. A filter can be constructed. Further, when the tap coefficient is calculated so that the TRF 104 has the LPF characteristic, crosstalk remains due to a change in the filter characteristic, or a sufficient LPF characteristic cannot be obtained if the tap coefficient value is small. A problem occurs, but as in this embodiment, FI
If R has the LPF characteristic, the LPF can be applied to the signal from which the crosstalk has been removed, so that the out-of-band signal and the ghost can be removed without affecting the crosstalk removal.

FIG. 2 is a block diagram showing a configuration example of the calculating means 108. 201 is a multiple signal input terminal, 202 is a crosstalk removal tap calculation means, 203 is a storage means,
Reference numeral 204 is a ghost removal tap computing means, 205 is an LPF
Tap coefficient output means, 206 is a convolution operation means, 20
7 is a TRF control signal output terminal, 208 is an IIR control signal output terminal, and 209 is an FIR control signal output terminal.

The multiple signal input terminal 201 is connected to the IIR 107.
Input the multiplexed signal output by. The crosstalk removal tap calculating means 202 detects crosstalk from the multiplexed signal input from the multiplex signal input terminal 201, calculates a tap coefficient for generating a crosstalk removal signal, and calculates T
Output from the RF control signal output terminal 207. The ghost elimination tap calculating means 204 detects a ghost from the multiplex signal input from the multiplex signal input terminal 201, calculates a tap coefficient for generating the ghost elimination signal, and II
The tap coefficient in the range of R is set to the IIR control signal output terminal 208.
And outputs the tap coefficient in the FIR range to the convolution operation means 206.

The LPF tap coefficient output means 205 stores the LPF tap coefficient values for removing signal components out of the band, and outputs them to the convolution operation means 206. The convolution operation means 206 performs a convolution operation on the tap coefficient output by the LPF tap coefficient output means 205 and the tap coefficient output by the ghost removal tap coefficient operation means 204,
The tap coefficient of the calculation result is set to the FIR control signal output terminal 209.
Output to. The storage unit 203 is used as a storage location for the input signal, the intermediate result of the operation, and the tap coefficient.

As described above, the result of the conventional tap coefficient calculation for ghost removal is subjected to the convolution operation with the LPF coefficient, so that the delay of the signal can be obtained only by adding the convolution operation means to the conventional system. It is possible to configure a ghost removal filter having a characteristic of removing a signal component outside the band without changing the amount.

FIG. 3 is a PAD diagram showing a ghost removing operation when the calculating means 108 is realized by software using a microprocessor or the like. First, the tap coefficient of the LPF for removing the out-of-band component of the multiplexed signal is set to FIR1
Transfer to 06. At this time, the FIR 106 operates as an LPF. Next, the reference signal inserted in the multiplex signal is taken in and its amplitude is normalized to a constant value.

An error is detected from the standardized reference signal. When this error becomes smaller than the preset reference value, it is determined that there is no ghost or that the ghost has been removed, and the ghost removal operation is terminated.

When the error is larger than the reference value, the tap coefficient for removing the ghost is set by the general ZF method or M
Calculation is performed using an algorithm such as SE method.

After that, in order to apply the LPF to the portion corresponding to the FIR 106 of this tap coefficient, FIR1
The convolution operation of the tap coefficient of 06 and the tap coefficient of the LPF is performed by the following equation.

[0027]

[Equation 1] TAP (I): I-th tap coefficient given to FIR T (I): I-th coefficient for removing ghost by FIR L (K): K-th coefficient of LPF realized by FIR (number of taps [2M + 1 ]) The result of the above convolution operation is transferred to the FIR 106, and the tap coefficient in the range where the convolution operation is not performed is I
Transfer to IR107. As a result, the signal output from the FIR 106 does not include an out-of-band component, so that the removal operation can be performed in a state where there is no out-of-band component that causes oscillation.

The operation up to here is performed from the acquisition of the reference signal to N
Repeat ghosts to complete ghost removal.

As described above, if the arithmetic means 108 is constituted by software using a microprocessor or the like, it is possible to change the signal delay amount without changing the signal delay amount by simply replacing the software of the conventional system. It is possible to realize a ghost removal filter having a characteristic of removing the signal component of.

[0030]

According to the present invention, even if the out-of-band signal component remains in the multiplexed signal after the crosstalk is removed, the out-of-band component can be removed together with the removal of the proximity ghost. Therefore, oscillation due to out-of-band components can be prevented and stable ghost removal can be performed.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing an example of the configuration of a calculation means shown in FIG.

FIG. 3 is a PAD diagram for explaining a ghost removing operation when the arithmetic means of FIG. 1 is implemented by software.

[Explanation of symbols]

101 ... Video signal input terminal, 102 ... Multiplex signal input terminal, 103 ... Ghost removing means, 104, 1061, 1
071 ... Transversal filter, 105, 106
2, 1072 ... Adder, 106 ... Non-cyclic filter, 1
07 ... Recursive filter, 108 ... Arithmetic means, 109 ... Multiplex signal output terminal, 201 ... Multiplex signal input terminal, 202 ...
Crosstalk removal tap calculation means, 203 ... Storage means,
204 ... Ghost removing tap computing means, 205 ... LPF
Tap coefficient output means, 206 ... convolution operation means, 20
7 ... TRF control signal output terminal, 208 ... IIR control signal output terminal, 209 ... FIR control signal output terminal.

Claims (1)

[Claims] 1. A quadrature in which a video carrier modulated by a video signal in which a reference signal for a video signal is inserted and a carrier in an orthogonal relationship with the video carrier are modulated by a multiplexing signal in which another reference signal is inserted. An apparatus for reproducing the video signal and the multiplexing signal from a transmission signal obtained by combining a carrier wave, the input video signal, and generating a signal for removing crosstalk of the video signal included in the multiplexing signal. A transversal filter, an adder that inputs the output of the transversal filter and the multiplex signal, and outputs a multiplex signal with crosstalk removed, and a multiplex signal that the adder outputs to input the proximity ghost and out of band. A non-recursive filter that removes the signal component of, and a recursive filter that removes a normal ghost by inputting the multiplexed signal output from the non-recursive filter, An output of the cyclic filter is input, and at least a calculation unit that controls the cyclic filter, the non-cyclic filter, and the transversal filter is provided, and the calculation unit is a crosstalk removal tap calculation unit,
Ghost removal tap calculation means, LPF tap coefficient output means for outputting tap coefficients of a low pass filter for removing signals outside the band, tap coefficient of the low pass filter and output of the ghost removal tap calculation means A two-dimensional waveform equalization device, comprising: a convolution operation means for performing a convolution operation of tap coefficients to be performed; and a storage means for storing an operation result.