JPH01240080A - Ghost removing device - Google Patents

Abstract

PURPOSE:To shorten a time necessary for a ghost removing processing to about 1/2 by starting the detection of a normal ghost at the same time as starting the detection of a nearby ghost. CONSTITUTION:A receiving television signal which is the object of ghost removing is supplied to an input terminal IN. A nearby ghost detecting part 12 detects the nearby ghost based on a reference waveform contained in the receiving television signal appearing in the input terminal IN, generates a tap gain to generate the most suitable pseudo nearby ghost and supplies it to a nearby ghost removing part 11. At the same time, a normal ghost detecting part 14 detects the normal ghost based on the reference waveform contained in the receiving television signal appearing in the input terminal IN, generates a tap gain to generate the most suitable pseudo normal ghost and supplies it to a normal ghost removing part 13. Thus, the time to the termination of the processing is shortened to about 1/2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a ghost removal device installed in a television receiver.

(Prior Art) A video signal received by a television receiver includes, in addition to signal components directly received by an antenna, some signal components that pass through various reflection paths from nearby trees, buildings, and moving objects such as vehicles. It also includes signal components that are received with a delay. Therefore, multiple images generally appear within the receiving screen, regardless of the degree of difference.

A signal component that causes multiple images to appear in the reception screen is called a ghost, and a phenomenon in which the multiple images become so large that they become an eyesore and the image quality deteriorates is called a ghost disturbance.

Such a ghost removal device is composed of a transversal filter for generating pseudo-ghosts, a tap gain control circuit that detects the occurrence of ghosts and controls the tap gain of the transversal filter, and a signal synthesis circuit. be done. This transversal filter generates pseudo-ghosts by imitating the mechanism of ghost generation based on multiple reflections of signal delay, attenuation, and mutual addition using a series of delay circuits, coefficient circuits, and addition circuits. do. This pseudo-ghost is usually generated with opposite polarity, is added to the original received television signal in a signal synthesis circuit, and is canceled out by the ghost component contained therein.

-a, ghosts change from time to time due to various factors such as changes in the wavelength of received radio waves due to switching of reception channels and changes in the traffic conditions of moving objects such as vehicles, ships, and aircraft passing or navigating nearby.

Therefore, the tap gain of the transversal filter is
It is adaptively controlled from time to time so that it is always at the optimum value. For this adaptive control, a reference waveform for detecting a ghost occurrence situation is inserted into the television signal on the transmitting side. Further, the tap gain control circuit on the reception side generates an optimal tap gain by detecting the occurrence of ghosts from the analysis result of the distortion of the reference waveform extracted from the received television signal, and supplies it to the transversal filter.

The above-mentioned ghosts are roughly classified into close ghosts and non-close ghosts depending on the degree of proximity to the original signal. That is, as shown in FIG. 13, if the original signal in the absence of a ghost is a waveform A shown by a dotted line, a nearby ghost causes waveform distortion as exemplified by the solid line portion α, and a non-proximal ghost causes a waveform distortion as illustrated by the solid line portion α. This causes waveform distortion as exemplified by the solid line portion β.

Non-proximity ghosts appear away from the original signal on the time axis, and tend to repeatedly appear at predetermined time intervals as parent ghosts, child ghosts, and grandchild ghosts gradually attenuate due to multiple reflections. Therefore, when removing this non-proximate ghost, it is desirable to perform cyclic synthesis of the pseudo ghost generated from the received television signal and the original received television signal. On the other hand, since the proximity ghost overlaps the original signal on the time axis, a portion preceding the original signal also appears in the generated proximity pseudo ghost. Therefore, cyclic synthesis cannot be applied to the generated pseudo-ghost and the original signal. In addition, regarding the proximity ghost, the waveform distortion caused by the ghost and the waveform distortion caused by the transmission characteristics occur inseparably, and the removal of the proximity ghost is considered to be a type of waveform equalization.

Therefore, the removal of proximal ghosts and non-proximal ghosts is usually not done by a single removal device, but by connecting dedicated removal devices in tandem to first remove the proximal ghosts and then remove the non-proximal ghosts. It is carried out in two stages. That is, as shown in FIG. 14, the entire ghost removal device includes a proximity ghost removal section 101a.
It is configured by cascade connection of a nearby ghost corresponding section consisting of a nearby ghost detecting section 101b and a normal ghost corresponding section consisting of a normal ghost removing section 102a (!=4 normal ghost detecting sections 102b).

As mentioned above, close-in ghosts are a special phenomenon that cannot be clearly separated from various factors in transmission characteristics that cause waveform distortion, whereas non-close-in ghosts are a phenomenon unique to ghosts, which is the formation of detour propagation paths. Based on. For this reason, non-proximity ghosts are often referred to as normal ghosts. In the following, this non-proximity ghost will be referred to as a normal ghost.

(Problems to be Solved by the Invention) In the ghost removal device, from the point of view of noise reduction, it is necessary to perform averaging processing several tens to hundreds of times on the reference waveform extracted from each frame of the received television signal. Ghost detection takes time. In the conventional ghost removal device shown in Fig. 14, detection and removal of ghosts usually starts after detection and removal of nearby ghosts is completed, so the entire process takes time, and There is a problem that it becomes impossible to deal with ghosts that change rapidly.

Furthermore, since the normal ghost is detected and removed using the signal after the proximity ghost has been removed, there is also a problem in that the detection characteristics of the normal ghost vary depending on the state of removal of the proximity ghost.

(Means for Solving the Problems) The ghost removal device of the present invention passes a received television signal appearing at an input terminal through a transversal filter to generate a pseudo-proximity ghost component, and combines this with the original received television signal. Proximity ghost removal means for removing proximity ghosts by combining them; and tap gain in the transversal filter of the proximity coast removal means for detecting proximity ghosts based on a predetermined reference waveform included in the received television signal appearing at the input terminal. and passing the received television signal output from the proximity ghost removal means through a transversal filter to generate a pseudo non-proximity ghost component. a non-proximity ghost removal unit that removes non-proximity ghosts by combining the signals with a television signal; and a non-proximity ghost removal unit that detects non-proximity ghosts based on a reference waveform included in the received television signal appearing at the input terminal. non-proximate ghost detection means for providing tap gain to the transversal filter.

That is, in the ghost removal apparatus of the present invention, detection of a nearby ghost and a non-proximal ghost is started at the same time, and the time required to complete the process is reduced by approximately half.

Furthermore, since the signal after removal of the proximity ghost is not used to detect the non-proximity ghost, it is possible to detect and remove the non-proximity ghost without being affected by the removal of the proximity ghost.

(Operation) Let G(jω) be the overall transfer characteristic including ghosts from the sending side to just before the ghost removing device on the receiving side, and let H(jω) be the transfer characteristic of the ideal ghost removing device. The ideal characteristic in the band is R(jω)
Then, G(jω)XH(jω) = R(jω)...
... (1) From equation (1), the transfer characteristic H of the ideal ghost removal device
(jω) is H(jω) = R(jω)/G(jω)... (2
) becomes.

G(jω) can be obtained by Fourier transforming the impulse response. For example, as a reference waveform
It can be easily determined by using a sin x/x pulse signal. Also, since the 5inx/x bar signal and the vertical synchronization signal can be treated as step responses, they can be converted to impulse responses by differentiating them, and G(
jω) can be obtained.

Transfer characteristic G(jω) up to just before the ghost removal device
is divided into a nearby ghost region and a normal ghost region, and the former is designated as Gl (jω) and the latter as G2 (jω). That is, G (jω) = 01 (jω) + 02 (jω)...
(3).

Using equation (3), equation (2) becomes H(jω) = R(jω)/[G1(jω)+G2 (jω)]=(
R(jω)/Gl(jω)] / (1+02 (jω)/Gl(jω)]...
(4) It is expressed as

Therefore, the transfer characteristic H(jω
) is Hl (j ω) = (R(jω)/Gl(jω))] ・ ・ ・ (5) H2(j ω) -1/C(1+02 (jω)/Gl(jω))]
The transfer function H1 (jω) of the proximity ghost filter and the transfer function H2 (jω) of the normal ghost removal filter are divided into two.

According to equation (5), the transfer function H1(jω) of the proximal ghost removal filter is the transfer characteristic Gl of the proximal ghost region.
(jω) and the ideal baseband characteristic R(jω). Further, as the coefficients of this proximity ghost removal filter, a value obtained by inverse Fourier transform of Hl (jω) may be used.

Furthermore, according to equation (6), the transfer function 82 (jω) of the normal ghost removal filter is determined from the transfer characteristic Gl (jω) of the nearby ghost region and the transfer characteristic G2 (jω) of the normal ghost Hff region. Also, the coefficient of this normal ghost removal filter is -02(jω)/G
What is necessary is to use the inverse Fourier transform of l(jω), and to make the configuration of this filter a cyclic type.

In this way, the coefficients of the ghost removal filter from close range to normal can be found just by knowing the signal input to the ghost removal device.

The coefficients of the proximity ghost removal filter obtained from equation (5) generally become an infinite length impulse response. Since the actual filter configuration has a finite length, the waveform finally obtained differs from the theoretical value, which causes residual ghosts.

Regarding this residual ghost, there is no problem in practice as long as the proximity ghost removal filter has a suitably wide range with respect to the proximity region to be removed. When the proximity ghost removal filter length is short, residual ghosts become a problem, but this can be solved as follows.

In other words, the transfer characteristic C(jω) of an ideal proximity ghost removal filter is: C(jω) = R(ja+) /Gl (jω)...
... (7) However, the transfer characteristic CI (jω) of the proximity ghost removal filter actually used is CI (jω) = C (jω) - E (jω) ... (8)
As shown, the error E(jω) with respect to the ideal value C(jω)
exists. Therefore, with respect to the overall transfer characteristic G(jω) including ghosts, the transfer characteristic after removing nearby ghosts is as follows from equations (3) and (8): G(jω)・C1(jω) = ( Gl(jω) ten G2 (jω)] x (C(jω) −E (jω))=R(jω)+
G2 (jω)・C(jω)−(Gl(jω)+02
(jω))E(jω)... (9) It becomes.

If the transfer characteristic of the normal ghost removal filter is C2(jω), then the final transfer characteristic after normal ghost removal is R(
jω), so G(jω)・CI (jω
)・C2(jω)=R(jω)
・ ・ ・ ・ The relationship (10) is obtained.

From equations (9) and (10), the transfer characteristic C2(jω) of the normal ghost removal filter is: C2(jω) = RCjω)/CG(jω)・C1(jω)]=R(j
ω)/(R(jω)+G2 (jω)・C(jω)−(
Gl (jω) + G2 (jω)] xE (jω)) = (1 + G2 (jω) / Gl (jω) - E (jω
)(Gl (jω)+02 (jω))/R(jω)
]-1... (11)

From equation (11), the coefficients of the recursive normal ghost removal filter are: G2 (jω)/Gl(jω) −E (jω)(Gl (jω)+02 (jω)
]/R(jω)] (12) An inverse Fourier transform of the following may be used.

Hereinafter, the more detailed structure and operation of the present invention will be explained together with examples.

(Embodiment) FIG. 1 is a block diagram showing the configuration of a ghost removal device according to an embodiment of the present invention, in which 11 is a proximity ghost removal section, 12 is a proximity ghost detection section, 13 is a normal ghost removal section, 14 is a normal ghost detection section.

A received television signal from which ghosts are to be removed is supplied to the input terminal IN. The proximity ghost detection unit 12 detects a proximity ghost based on a reference waveform included in the received television signal appearing at the input terminal IN, generates a tap gain for generating an optimal pseudo proximity ghost, and uses this as a proximity ghost. The signal is supplied to the ghost removal section 11.

Simultaneously with the start of detecting a nearby ghost by the nearby ghost detecting section 12, the normal ghost detecting section 14 connects the input terminal I
A normal ghost is detected based on a reference waveform included in the received television signal appearing in N, a tap gain for generating an optimal original image normal ghost is generated, and this is supplied to the normal ghost removal section 13.

As shown in FIG. 2, the proximity ghost removal unit 11 includes an original image proximity ghost generation circuit 11a composed of a transversal filter, a delay circuit 11b, and an addition circuit 11c.
It has an acyclic configuration. The pseudo proximity ghost generation circuit 11a generates a pseudo proximity ghost according to the tap gain supplied from the proximity ghost detection section 12, and supplies it to one input terminal of the addition circuit 11c. The adder circuit 11c eliminates the proximity ghost in the received television signal by adding the pseudo proximity ghost supplied to one input terminal and the original received television signal supplied to the other input terminal via the delay circuit 1b. Remove and output terminal O
Supply to UT.

As shown in FIG. 3, the normal ghost removal unit 13 has a cyclic configuration including a pseudo normal ghost generation circuit 13a composed of a transversal filter and an adder circuit 13b. The pseudo-normal ghost generation circuit 13a is
A pseudo-normal ghost is generated according to the tap gain supplied from the normal ghost detection section 14, and is supplied to one input terminal of the adder circuit 13b. The adder circuit 13b adds the pseudo normal ghost supplied to one input terminal and the original received television signal supplied to the input terminal I from the preceding stage proximity ghost removal section 11, thereby eliminating the normal ghost in the received television signal. The ghost is removed and the signal is supplied to output terminal 0.

Transversal filter 1 configuring the pseudo-proximity ghost generation circuit 11a and the pseudo-normal ghost generation circuit 13a
As shown in FIG. 4, there are a plurality of delay devices 42a, 42b, 42c, . , 43C...43n and a transversal filter section including an adder 44 that adds the respective outputs of these multipliers, and a tap supplied from the proximity ghost detection section 12 or the normal ghost detection section 14. Generates original image proximity ghosts and pseudo-normal ghosts based on gain.

As shown in FIG. 5, the proximity ghost detection section 12 in FIG. section 57, an inverse Fourier transform section 58, and a tap gain holding register 59. The reference waveform extracting section 52 includes an extracted waveform holding section 52a, an adding section 52b, and a reference waveform detecting section 52C.

On the transmission side of the television signal, a reference waveform S0 (t
) is inserted. This reference signal waveform SO(t) is obtained by band-limiting the impulse waveform by passing it through a low-pass filter circuit having an amplitude-frequency characteristic as shown in FIG. 6(B).

On the other hand, the reference waveform Fourier coefficient holding unit 55 in the proximity ghost detection unit 12 shown in FIG. A coefficient group R(jω) is held in advance. This Fourier coefficient R(jω) is nothing but a low-pass amplitude-frequency characteristic expressed by a group of discrete sampling values as shown in FIG. 6(B).

Actual reference waveform S included in the received television signal
(t) is extracted from a predetermined location in the television signal after passing through the input terminal I and the A/D converter 51 in FIG. written. In order to reduce noise in the extracted reference waveform, time averaging over a plurality of extraction times is performed by connecting the input and output terminals of the extracted waveform holding section 52a via the adding section 52b. This received and extracted reference waveform S (t) is affected by the transmission characteristics including ghosts, so that the reference waveform So (t) inserted at the transmitting side is The waveform becomes distorted.

The received reference waveform S (t) is read out from the extracted waveform holding unit 52a, and Fourier transformed in the Fourier transform unit 54 over a close region near the change point of the reference waveform, and is converted into a discrete waveform as shown in FIG. 7(B). is converted into a set of Fourier transform coefficients C1(jω). In addition, Ic; 11 in the figure
(jω) is the amplitude, and zGl(jω) is the amount of phase rotation.

The dividing unit 56 divides the reference waveform Fourier coefficient R(jω) read from the reference waveform Fourier coefficient holding unit 55 by the Fourier coefficient Gl(jω) of the corresponding frequency component received from the Fourier transform unit 54. , the transfer characteristic of the near ghost removal Fourier transform Hl (jω) = R(jω)/Gl(jω) (13) is generated.

Therefore, the division result of the division section 56 is transferred to the inverse Fourier transform section 5.
By performing inverse Fourier transform in step 8 and using this as the tap gain of the transversal filter in the proximity ghost removal section 11, a pseudo proximity ghost can be generated.

Note that the correction unit 57 adjusts the frequency characteristics of the division value output from the division unit 56, considers a steep drop in a specific frequency of the division value to be a beat disturbance, and raises it to the level of a peripheral division value, etc. Performs correction processing.

The normal ghost detection section 14 in FIG. 1 includes an A/D converter 61, a reference extraction section 62, a reference waveform correction section 64, and a tap gain holding register 67, as shown in FIG.

The reference waveform extraction section 62 includes an extracted waveform holding section 62a, an addition section 62b, and a reference waveform detection section 62.

The received television signal to be ghost removed appearing on the input terminal IN of FIG. 1 is supplied to the input terminal I of the normal ghost detection section 14 of FIG.

The reference waveform included in this received television signal is A/
It is converted into a digital signal by the D converter 61, extracted from a predetermined position in the television signal after timing control by the reference waveform detection section 62c, and written into the extracted waveform holding section 62a. In order to reduce noise in the extracted reference waveform, the input and output terminals of the extracted waveform holding section 62a are connected via the adding section 62b, and time averaging over a plurality of extraction times is performed.

The extracted waveform holding unit 62a extracts and holds the actual reference waveform S(t) distorted by ghosts from the received television signal. If a nearby ghost does not appear in the received television signal, the normal region of the extracted reference waveform S (t) can be treated as an impulse response in which the normal ghost component is a normal region. In this case, the tap gain to be supplied to the transversal filter of the normal ghost removal section 13 can be generated immediately. However, since the television signal directly input to the normal ghost detection unit 14 from the input terminal IN in FIG. 1 has not yet been subjected to proximity ghost removal, the detection accuracy of normal ghosts is reduced due to its influence. In order to compensate for this decrease in detection accuracy of normal ghosts, a reference waveform correction section 64 is provided that corrects the reference waveform on the side of the extracted waveform holding section 62a.

This reference waveform correction section 64 includes the normal domain Fourier transform section 6
4a, proximity area Fourier transform section 64b, reciprocal calculation section 64
c, a division section 64d, and an inverse Fourier transform section 64d.

The reference waveform read out from the extracted waveform holding unit 62a is converted into a Fourier coefficient 0 by a normal area Fourier transform unit 64a that performs Fourier transform on the normal area after the change point of the reference waveform.
2 (jω) and is supplied to one input terminal of the divider 64C. At the same time, the reference waveform read out from the extracted waveform holding section 62a is transferred to the near area Fourier transform section 6 which performs Fourier transform on the near area near the change point of the reference waveform.
4b, it is converted into a Fourier coefficient Gl (jω), and a reciprocal calculation circuit 64c converts it into a reciprocal, which is then supplied to the other input terminal of the divider 64c.

The division unit 64c calculates the Fourier coefficient 02 (jω) in the normal region.
By dividing by the Fourier coefficient Gl (jω) of the adjacent region and inverting the sign, the transfer characteristic of the normal ghost removal filter -G2 (jω)/Gl(jω) (14) is generated.

Therefore, the division result of the division section 64C is converted into the inverse Fourier transform section 64C.
4d, and if this is used as the tap gain of the transversal filter in the normal ghost removal section 13, it is possible to generate a pseudo-normal ghost.

Note that the reference waveform extraction unit 62, A/D converter 61, and proximity area Fourier transform unit 64 in the normal ghost detection unit 14 in FIG. 8 are omitted, and the reference waveform extraction unit in the proximity ghost detection unit 12 in FIG. The outputs of the section 52, the A/D converter 51, and the near-area Fourier transform section 54 may be used as they are.

FIG. 9 is a block diagram showing the configuration of a ghost removal device according to another embodiment of the present invention, in which 91 is a proximity ghost removal section, 92 is a proximity ghost detection section, 93 is a normal ghost removal section, and 94 is a normal ghost removal section. This is the detection part.

The proximity ghost removal section 91 and the normal ghost removal section 93 are
Since the structure and function are the same as each of the proximal ghost removal section 11 and the normal ghost removal section 13 in the ghost removal apparatus shown in FIG. 1, a redundant explanation of these will be omitted.

A received television signal from which ghosts are to be removed is supplied to the input terminal IN. The proximity ghost detection unit 92 detects a proximity ghost based on the reference waveform included in the received television signal appearing at the input terminal IN, and determines the optimal tap gain for generating the optimal pseudo proximity ghost and the most optimal tap gain for generating the optimal pseudo proximity ghost. A close tap gain corresponding to the transversal filter length of the proximal ghost removal section 91 and a tap gain error corresponding to the difference between this tap gain and the optimal tap gain are generated. The proximity ghost detection section 92 supplies the proximity ghost removal section 91 with a tap gain corresponding to the transversal filter length, and also supplies the tap gain error to the normal ghost detection section 94 .

The normal ghost detection unit 94 includes the proximity ghost detection unit 9
In parallel with the detection of a nearby ghost by 2, the input terminal IN
A normal ghost is detected based on the reference waveform included in the received television signal appearing in the received television signal and the tap gain error of the near ghost removal filter supplied from the near ghost detection section 92, and an optimal original normal ghost is generated. , and supplies this to the normal ghost removal section 93.

As shown in FIG. 10, the proximity ghost detection section 92 has a configuration in which a coefficient window 60 is added to the proximity ghost detection section 12 of the first described embodiment (see FIG. 5). 1st
The remaining components of the nearby ghost detection section 92 in FIG. 0, which are denoted by the same reference numerals as those in FIG. Duplicate explanations regarding these will be omitted.

The inverse Fourier transform output C(t) of the transfer characteristic of the proximity ghost removal filter generated by the inverse Fourier transform unit 58 generally becomes an infinite impulse response as illustrated in FIG. 11(A). On the other hand, since the number of taps of the transversal filter in the proximity ghost removal section 91 is finite as -b≦t≦a in FIG. 11(A), tap gains also appear outside this range. It turns out. In this case, if the taps of the transversal filter in the normal ghost removal section 93 are in the range C≦t, the coefficient window 60 is
The ideal proximal ghost removal filter coefficient C(t) generated by the inverse Fourier transform unit 58 is multiplied by a window function W (t) as illustrated in FIG. The coefficient C1(t) that matches the number of taps of the transversal filter is stored in the tap gain holding register 5.
Supply to 9. Further, the coefficient window 60 calculates the error E (t) of C (t) approximated by the window function W (t) excluding the front ghost, and sends this to the output terminal Eo connected to the normal ghost detection section 94. supply

As shown in FIG. 12, the normal ghost detection section 94 has a configuration in which only the reference waveform correction section 64 is changed from the normal ghost detection section 14 of the first described embodiment (see FIG. 8). Components in the normal ghost detection section 94 in FIG. 11 that are denoted by the same reference numerals as in FIG. 8 are the same as the components already described with respect to the normal ghost detection section 94 in FIG. Duplicate explanations regarding these will be omitted.

The reference waveform correction section 64 includes a normal domain Fourier transform section 64a.
, a proximity area Fourier transform unit 64b, a reference waveform Fourier coefficient holding unit 64e, a proximity error Fourier transform unit 64f, a division/proximity error compensation unit 64g, and an inverse Fourier transform unit 64(l).
It consists of

The reference waveform Fourier coefficient holding section 64e contains the information shown in FIG. 6(A).
A discrete Fourier transform coefficient group R(jω) created by Fourier transforming the reference waveform SO(t) shown in is stored in advance.

The reference waveform read from the extracted waveform holding unit 62a is converted into a Fourier coefficient 02 (
jω) and supplied to one of the input terminals of the division/proximity error compensator 64g. In parallel with this, the reference waveform read from the extracted waveform holding section 62a is converted into a Fourier coefficient Gl (jω) by a near-area Fourier transform section 64b that performs Fourier transform on the near-field near the change point, and then - Supplied to one of the input terminals of the proximity error compensator 64g.

The error E(t) in the tap gain of the proximity ghost removal filter supplied from the input terminal Ei is converted into a proximity error Fourier coefficient E(jω) by the proximity error Fourier transform unit 64f, and then converted into a proximity error Fourier coefficient E(jω) by the division/proximity error compensation unit 64g. supplied to one of the input terminals. The reference waveform Fourier coefficient R(jω) output from the reference waveform Fourier coefficient holding section 64e is supplied to the remaining one input terminal of the division/proximity error compensating section 64g.

The division/proximity error compensator 64g uses the Fourier coefficients 02 in the normal area supplied from each of the above units to each of the input terminals.
(jω), Fourier coefficient Gl of the nearby region (jω),
The above-mentioned equation (12) is calculated from the proximity error Fourier coefficient E (jω) and the reference waveform Fourier coefficient R (jω),
The transfer characteristic of the normal ghost removal filter including the residual ghost component of the proximity ghost removal is generated.

The output from the division/proximity error compensator 64g is subjected to inverse Fourier transform in an inverse Fourier transform unit 64d, and is supplied from the tap gain holding register 67 to the transversal filter in the normal ghost divider 93. As a result, a pseudo normal ghost that also includes the residual ghost component during the removal of the close ghost is generated by the transversal filter in the normal ghost removal unit 93.

Although a configuration using a band-limited impulse as the reference waveform has been described above, other appropriate waveforms such as a step waveform differentiated and band-limited may also be used.

Note that the above-described proximity/normal ghost detection/removal unit can be realized by either hardware or software, or by a mixture of both.

(Effects of the Invention) As described above in detail, the ghost removal device of the present invention is configured to start detecting a normal ghost at the same time as detecting a nearby ghost. This has the effect of significantly improving the ability to follow high-speed ghosts caused by moving objects and the like.

Furthermore, since the ghost removal device of the present invention is configured to use a signal before proximity ghost removal to detect normal ghosts, the effect is that it is possible to stably remove normal ghosts without being affected by proximity ghost removal. is played.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a ghost removal device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the proximity ghost removal section in FIG. A block diagram showing the configuration of the removal block, FIG.
FIG. 5 is a block diagram showing an example of the configuration of the pseudo-proximity ghost generation circuit shown in FIG. 3 and the pseudo-normal ghost generation circuit shown in FIG. FIG. 7 is a conceptual diagram for explaining the operation of the circuit shown in FIG. 5, and FIG. 8 is a conceptual diagram for explaining the operation of the circuit shown in FIG.
9 is a block diagram showing the configuration of a ghost removal device according to another embodiment of the present invention. FIG. 10 is a block diagram showing the configuration of the nearby ghost detection section 92 of FIG. FIG. 11 is a conceptual diagram for explaining the operation of the device shown in FIG. 9, FIG. 12 is a block diagram showing the configuration of the normal ghost detection section 94 shown in FIG. 9, and FIG. FIG. 14 is a waveform diagram for explanation and a block diagram showing the configuration of a conventional ghost removal device. 11.91... Proximity ghost removal unit, lla... Pseudo proximity ghost generation circuit, llb... Delay circuit, ll
c... Addition circuit, 12.92... Proximity ghost detection section, 13.93... Normal (non-proximity) ghost removal section,
13a... Pseudo-normal ghost generation section, 13b... Addition circuit, 14.94... Normal ghost detection section. Patent applicant: NEC Home Electronics Co., Ltd.

Claims (1)

[Claims] (1) The received television signal appearing at the input terminal is passed through a transversal filter to generate a pseudo proximity ghost component, and this is combined with the original received television signal to remove the proximity ghost. and a nearby ghost that detects a nearby ghost based on a predetermined reference waveform included in a received television signal appearing at the input terminal and supplies a tap gain to a transversal filter of the nearby ghost remover. detection means; passing the received television signal output from the proximity ghost removal unit through a transversal filter to generate a pseudo non-proximity ghost component, and combining this with the reception television signal output from the proximity ghost removal unit; non-proximity ghost removal means for combining and removing non-proximity ghosts; and transversal processing of the non-proximity ghost removal means for detecting non-proximity ghosts based on a reference waveform included in the received television signal appearing at the input terminal. A ghost removal device comprising non-proximity ghost detection means for supplying a tap gain to a filter. (2) The proximity ghost detection means includes a reference waveform extraction means that converts and extracts a reference waveform included in the television reception signal appearing at the input terminal into a digital signal, and a reference waveform that performs Fourier transform on the extracted reference waveform. A waveform Fourier transform means and a Fourier coefficient obtained by Fourier transforming an undistorted reference waveform to be inserted into a television signal before transmission, which is stored in a memory, read out and output, or which retains the undistorted reference waveform in a memory. a reference waveform Fourier coefficient output means for reading out and outputting Fourier-transformed Fourier coefficients, and dividing the reference waveform Fourier coefficient output from the reference waveform Fourier coefficient output means by the output of the reference waveform Fourier transform section, 2. The ghost removal apparatus according to claim 1, further comprising processing means for supplying the converted result as a tap gain to the transversal filter of the non-proximity ghost removal means. (3) The non-proximity ghost detection means includes a reference waveform extraction means for converting and extracting a reference waveform included in the received television signal appearing at the input terminal into a digital signal, and a nearby area of the extracted reference waveform. Each of the non-proximal regions is Fourier-transformed individually, the Fourier transform coefficient of the non-proximal region is divided by the Fourier transform coefficient of the proximal region, and the division result is inversely Fourier-transformed and used as a tap gain in the transformer of the non-proximal ghost removal means. 4. The ghost removal device according to claim 3, further comprising a versal filter. (4) The reference waveform extracting means extracts the reference waveform included in the television reception signal appearing at the input terminal while averaging the reference waveform over a plurality of occurrences. The ghost removal device according to item 3. (5) The non-proximity ghost removal means is characterized by comprising a cyclic synthesis means for synthesizing the received television signal output from the proximal ghost removal means and the pseudo non-proximity ghost generated therefrom. A ghost removal device according to claims 1 to 4. (6) The ghost removal device according to any one of claims 1 to 5, wherein the reference waveform is a waveform obtained by band-limiting an impulse waveform. (7) The ghost removal device according to any one of claims 1 to 5, wherein the reference waveform is a waveform obtained by differentiating and band-limiting a step waveform.