JPH01209882A - Ghost removing device - Google Patents

Abstract

PURPOSE:To remove the ghost of a wide range by correcting the respective tap gains of first and second dependently connected ghost removing parts based on a first reference signal included in an external incoming signal and a second reference signal different in a timing therefrom. CONSTITUTION:The tap gain is applied to the respective taps of transversal filters 102, 202 from tap gain memories 103, 203 to correct the data of the tap gain memories 103, 203 in an operating part 104 at the time of the incoming of the reference signal. Then, a cancel signal from the transversal filters 102, 202 and the external incoming signal are subtracted 101, 102 to remove the ghost. Such ghost removing parts are dependently connected to correct the respective tap gains based on the first reference signal included in the external incoming signal of the first and the second removing parts 100, 200 and the second reference signal different in the timing by the delay time of a delay circuit 107 therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a ghost removal device for removing ghosts in a television signal processing system.

(Prior Art) In general, a ghost removal device using a transversal filter includes a part that gives a tap gain to the transversal filter, and a part that provides a tap gain to the transversal filter, and a part that provides a tap gain to the transversal filter, and a part that determines the position of the ghost and whether the ghost is positive or negative by referring to the transmitted reference signal. It consists of means for detecting the level and means for modifying tap gain data in the tap gain memory based on the detection result.

Ghosts are removed by adding the cancellation signal obtained from the transversal filter section to the original input signal with opposite polarity.

As the reference signal, two methods are used: one is to differentiate the rising edge of the vertical synchronization signal, and the other is to insert and transmit an impulse-like reference signal in the center of the flat part of the horizontal period in the vertical retrace period. There is.

(Problems to be Solved by the Invention) Conventional ghost removal devices perform ghost detection using one type of the above reference signal.

That is, as shown in FIG. 9, in the method of transmitting an impulse-like reference signal, the reference signal A1 is inserted at the center of one horizontal period. Further, even in the method using the square wave-shaped reference signal A2, the level change point is inserted so as to be located at the center of one horizontal period. If you try to detect the ghost position using such a reference signal, it will take about 24 μS.
Ghosts can only be detected within the range up to ee, and it is impossible to detect ghosts that are delayed any further. Therefore,
If a ghost with a delay of 24 μSQC or more was present, it was impossible to remove it using conventional equipment.

Therefore, in this invention, the ghost is 24μS lower than the reference signal.
It is an object of the present invention to provide a ghost removal device capable of detecting and removing a ghost even if it exists at a position delayed by more than ee.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a transversal filter, a tap gain memory storing tap gains to be given to each tap of the transversal filter, and data stored in the tap gain memory when a reference signal arrives. a first ghost removing unit that removes ghosts by adding the cancellation (m) from the transversal filter and an incoming signal from the outside; A second ghost removal section having a similar configuration is connected in a subordinate manner.The second ghost removal section is connected to the first reference number 1 included in the external arriving signal. In this example, each tap gain is corrected based on a second reference Q having a different timing.

(Function) With the above means, it is possible to create a ghost detection period handled by the first ghost removal section and a ghost detection period handled by the second ghost removal section, thereby expanding the ghost detection section and the ghost removal range. can.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the apparatus of the present invention, two types of reference signals are transmitted in advance from the transmitting side, and an example of the reference signals will be explained with reference to FIG.

As shown in FIG. 2(a), the reference signal used in this device has an impulse waveform approximately in the center of the 1st and 19th periods, and the reference signal A1 has an impulse waveform approximately 24μs from this impulse waveform.
A ghost detection section is set in period c. Reference signal B
In No. 1, an impulse waveform is set at a position earlier than the reference signal A2, and a ghost detection section is set in a section further after the 24 μSee period from this impulse waveform.

The ghost removal device connects two ghost removal units (described later) in series.

In the first ghost removal section, when the reference signal B1 arrives, a ghost existing in a section 24 μSee later than the reference signal B1 is detected. Then, in the transversal filter section, the tap gain is corrected according to the delay time to the ghost, a cancellation signal with the opposite polarity is generated for the ghost, and the ghost is removed by adding this cancellation signal and the original signal. .

In the second ghost removal section, when the reference signal A1 arrives, it is detected whether or not there is a signal (ghost) similar to the reference signal in a 24 μsec period after the reference signal. If a ghost is detected from the input signal (No. 5), the tap gain of the transversal filter section corresponding to the delay time from the reference signal A1 to the ghost is corrected and a cancellation signal is issued. , is added to the original input signal with the opposite polarity.This yields an output signal from which ghosts have been removed, but further ghost detection is performed, and if ghosts remain, the data in the memory is corrected by tapping again. Ru.

Next, an apparatus for removing the ghost described above will be explained with reference to FIG.

In FIG. 1, a first ghost removal section 100 and a second ghost removal section 200 perform ghost detection using a reference signal B1 and ghost detection using a reference signal A1, respectively, and have different ghost detection sections. . In the embodiment of the present invention, the reference signals A1 and B1 are inserted into a predetermined line (for example, the 17th line) of the vertical retrace interval of the television signal, and after the reference signal A1 continues P times, the reference signal B
It is assumed that the data is transmitted with one 1 inserted.

The input video signal is supplied to the subtracter 101 of the first ghost removal section 100 via the terminal 11.

The subtracter 101 subtracts the ghost cancellation signal from the input video signal to remove the ghost, and uses the output as the next second signal.
is supplied to the ghost removal section 200 of.

1st. The second ghost removal unit 100.200 will be explained.

The first ghost removal unit 100 includes a subtracter 101 , a transversal filter unit 102 , a tap gain memory 103 that provides a tap gain for each tap of the transversal filter unit 102 , and a tap gain memory 103 that provides a tap gain for each tap of the transversal filter unit 102 .
and a correlation calculation unit 104 that corrects the stored data.

The transversal filter section 102 connects a plurality of delay elements in series, and connects a multiplier to the connection point of each delay element.
The configuration is such that the outputs of each multiplier are added together using an adder.

The output of the adder is supplied to the preceding arithmetic unit as a cancellation signal. A tap gain control signal is given to each multiplier from the tap gain memory 103.

The transversal filter section 102 includes a subtracter 101
The output is inputted via the delay circuit 107. The delay circuit 107 is used to set a period in which the transversal filter section 102 performs ghost cancellation processing.

The output of subtracter 101 is also supplied to subtracter 105.

The subtracter 105 performs subtraction processing between the output of the reference waveform memory 106 and the signal from the subtracter 101 in the section handled by the first ghost removal unit 100 . If the signal from subtracter 101 is only reference signal B1, the output of subtracter 105 is zero. However, if a residual ghost is included, that component will be detected.

The output of the subtracter 105 is input to the correlation calculation unit 104.The correlation calculation unit 104 uses the detection signal and the reference signal B1 to calculate the location and polarity of the ghost, and calculates the location and polarity of the ghost in the corresponding tap gain memory 103. Correct tap gain data.

The first ghost removal section 100 described above uses the reference signal B1 shown in FIG. 2 as a reference to detect and remove ghosts in the ghost detection section.

The operational sequence of the first ghost removal section 100 is performed based on the timing signal from the timing generation section 300. That is, the correlation calculation section 104 introduces the ghost detection signal into the interval of the gate pulse S1 from the timing generation section 300 and performs the correlation calculation process. For example, the ghost detectable range after the impulse part of the reference signal B1 is MT (T: unit delay amount of the delay element, M: number of connected delay elements), and the interval in which ghost detection is performed based on the reference signal A1 is NT. If so, the gate pulse S1 is generated in the (M−N)T interval after the interval NT.

The second ghost removal unit 200 also has the same configuration as the first removal unit 100, and includes a transversal filter unit 201,
It is composed of a tap gain memory 203, a correlation calculation section 205, and a reference waveform memory 206. However, the difference from the first ghost remover 100 is that, as shown in FIG. 2, the second ghost remover 200 detects and removes ghosts based on the reference waveform A1. The detection interval is different. The operation sequence in this ghost removal section 2001:l is also performed based on the timing signal from the timing generation section 300.

That is, the correlation calculation section 300 is the timing generation section 300.
A ghost detection signal is introduced into the section (NT) of the gate signal S2 from . Subtractor 2 of second ghost removal unit 200
When a residual ghost is detected in step 05, the correlation calculation unit 204 controls the tap gain of the tap gain memory 203 to correct the tap gain at the position corresponding to the ghost. As a result, a cancellation signal for removing ghosts is obtained from the ghost transversal filter section 202 and is supplied to the subtracter 201. Therefore, a video signal from which ghosts have been removed can be obtained at the output terminal 12.

As described above, according to this embodiment, the first and second ghost removal units 100 and 2 have different sections in charge of ghost removal.
00 is connected in a subordinate manner, the ghost detection section can be expanded and the ghost removal range can also be expanded.

For example, as shown in FIG. 2(b), when a ghost with a large delay time exists, it is impossible to detect the ghost using the conventional detection method based on the reference signal A1. However, as in this embodiment, by using the reference signal B1 in combination, even if a ghost with a large delay time (greater than 24 μsOe) exists, it can be removed in the first ghost removal unit 100, resulting in a better image. I can get a signal. As shown in Figure 2(b),
The ghosts (indicated by broken lines) of the horizontal synchronization signal and the burst signal are detected by the second
Even if ghosts of horizontal synchronization signals and burst signals exist within the processing range of the ghost removal unit 200, if complete ghost removal is performed by the first ghost removal unit 100, ghosts of horizontal synchronization signals and burst signals will be present within the processing range of the second ghost removal unit 200. will no longer be mixed in.

Therefore, the probability that the second ghost removal unit 200 responds to an erroneous ghost (a ghost of a horizontal synchronization signal or a burst signal) without detecting the original ghost is also reduced.

In the above embodiment, ghost detection was performed using an impulse waveform as a reference signal. However, the present invention is not limited to this, and a reference signal as shown in FIG. 4 may be used. Reference signal A
1, a rectangular wave is superimposed on the horizontal line during the vertical retrace period and transmitted as in the conventional method. The fall position of the rectangular wave is approximately at the center of the horizontal period. On the other hand, the reference signal B1 is the falling part of the vertical synchronizing signal, and the equivalent pulses (indicated by broken lines) before and after the falling part are deleted and transmitted.

Even if such reference signals Bl and AI are used, ghost detection sections (M-N) T and NT similar to those explained in FIG. 2 can be provided. However, the reference signal Bl in FIG.
In order to utilize AI, as shown in FIG.
Differentiator 1 to detect the error component (residual ghost) between
It is necessary to provide 07. Further, it is necessary to store rectangular waveform reference waveform data in the reference waveform memory 106. It is necessary to provide differentiators 208 and 207 at similar locations in the second ghost removal section 200 as well.

In the above embodiment as well, the same effects as in the embodiment shown in FIG. 1 can be obtained.

FIG. 5 shows yet another embodiment. In this embodiment, the second ghost removal section 200 is further divided into a feedforward type ghost removal section and a feedback type ghost removal section. The feedforward type ghost removal section includes a delay circuit 401 and a transversal filter section 402 to which the output from the first ghost removal section 100 is supplied. Transversal filter section 402
The output cancellation signal from the delay circuit 401 becomes a subtracted component with respect to the output from the delay circuit 401 and is supplied to the subtracter 403 .

The output of the subtraction 5403 is input to a subtractor 405 forming a feedback type ghost removal section. Subtractor 40
In step 5, a cancellation signal from the transversal filter section 407 is also manually input, and ghost removal is performed.

The output of the subtracter 405 is led out to the output terminal 12 and is inputted to the transversal filter section 407 and the subtracter 409 via the delay circuit 406. In the subtracter 409, residual ghost detection is performed with reference to the output of the reference waveform memory 410, and the output is supplied to the correlation calculation section 411. The correlation calculation unit 411 modifies the data in the tap gain memory 404 or 408 in order to modify the tap gain of the corresponding tap according to the delay of the ghost.

Tap gain 11: The outputs of the memories 404 and 408 are supplied to the multipliers of the corresponding taps of the transversal filter sections 402 and 407, respectively, to determine the magnitude of the cancellation signal.

All of the embodiments described above are based on the concept of using two reference signals, but the number of reference signals may be further increased to subdivide the ghost detection and removal section. Then, the number of taps in each ghost removal section can be increased, which is effective in removing ghosts that are closer to each other.

FIGS. 6 and 7 each show examples of three reference signals.

When the reference signals A1 and B1 are used, ghosts in the ranges of the sections NT and MT can be detected, respectively, as explained in the previous embodiment. In addition to this, by using the reference No. 15 CI, it is possible to detect ghosts within the further expanded section LT. However, as described in the previous embodiment, the ghost removal sections that use each reference signal are arranged in time so that the ghost detection sections do not overlap. When using the reference signal C1, a third ghost remover 500 is further provided between the input terminal 11 and the ghost remover 100, as shown in FIG. This ghost removal section 500 also has the same configuration as the ghost removal section described above, and includes a transversal filter section, a delay circuit, and the like. However, the reception section for ghost detection and removal is set to be different from that of the first and second ghost removal sections 100 and 200.

[Effects of the Invention] As described above, according to the present invention, the ghost detection section can be expanded and ghosts in a wide range can be removed.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the waveform of a base signal shown to explain the operation of the ghost removal device of the present invention, and FIG. A circuit diagram showing another embodiment, FIG. 4 is a diagram showing the waveform of the reference signal used in the circuit of FIG. 3, FIG. 5 is a circuit diagram showing still another embodiment of the present invention, and FIGS. FIG. 7 is a diagram showing still another example of the reference signal, FIG. 8 is a circuit diagram showing still another embodiment of the present invention, and FIG. 9 is a diagram showing still another example of the reference signal used in the conventional ghost removal device. It is a figure which shows a waveform. 100...first ghost removal section, 200...second
Ghost removal section, 300...timing generation section, 1
(11,201, IO'5.2 (15...subtractor, 1
02.2 (12...transversal filter, 10
3.203...Tap interest 11.1 memory, 104°2
04... Correlation calculation unit, 106, 206... Reference waveform memory. Applicant's agent Patent attorney Takehiko Suzue (a) (b) Figure 2 Factor 4 Figure 6 Figure 7

Claims (1)

[Claims] a transversal filter; a tap gain memory storing tap gains to be given to each tap of the transversal filter; gain modification means for modifying data in the tap gain memory when a reference signal arrives; A first ghost removal section that removes ghosts by adding the cancellation signal of the cancellation signal and an incoming signal from the outside, and a second ghost removal section that has a similar configuration to the first ghost removal section are connected in a subordinate manner, means for causing the first and second ghost removal sections to perform respective tap gain corrections based on a first reference signal included in the externally arriving signal and a second reference signal having a timing different from the first reference signal; A ghost removal device characterized by comprising: