JPH01209883A - Ghost removing device - Google Patents

Abstract

PURPOSE:To eliminate an adverse influence applied to a ghost detection by generating no cancel signal by one removing part when the other removing part detects the ghost in a device for obtaining the cancel signal by the dependently connected ghost removing parts to have a constant tap gain. CONSTITUTION:The first and the second ghost removing parts 100, 200 consisting of a transversal filter, a tap gain register, a tap gain memory, and a correcting means for correcting the data of the tap gain memory at the time of the incoming of a reference signal are provided. Into a transmitting signal, the first reference signal and the second reference signal different in an incoming timing therefrom and obtained by subtracting 31 the output of a reference waveform memory 32 are inserted. Then, the first and the second ghost removing parts are associated and during a period in which the second ghost removing part 200 operates to correct data in the tap gain memory 203 based on the second reference signal, the contents of the tap gain register 101 are switched to be a predetermined fixed value in the first ghost removing part 100.

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.

(Problem to be Solved by the Invention) A conventional ghost removal device detects a ghost by using the above-mentioned reference signal as an IFI.

That is, as shown in FIG. 2, 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. When trying to detect a ghost position using such a reference signal, it takes approximately 24 μs.
Ghosts can only be detected within a range up to ec, and it is impossible to detect ghosts that are delayed any further. Therefore,
If a ghost with a delay of 24 μsee or more was present, it was impossible to remove it using conventional devices.

Therefore, in this invention, the ghost is 24Bs lower than the reference signal.
Even if it exists at a position delayed by more than ec, it can be detected and removed, and in this case, multiple ghost canceling units are used, but the mutual canceling units should operate in such a way that they do not interfere with each other. It is an object of the present invention to provide a ghost removal device that achieves the following.

[Structure of the invention] (Means for solving problems) This invention is a transversal filter.

The present invention includes a first and a second ghost removal section each having a tap gain register, a tap gain memory, and a gain modification means for modifying data in the tap gain memory when a reference signal arrives. On the other hand, a first reference signal and a second reference signal whose arrival timing is different from the first reference signal are inserted into the transmission signal. and a second ghost remover, and during a period in which the second ghost remover performs an operation to correct data in its tap gain memory based on the second reference signal, the first The ghost removal unit is configured to switch the contents of the tap gain register to a predetermined fixed value.

(Function) With the above-described first stage, a ghost detection period handled by the first ghost removal section and a ghost detection period handled by the second ghost removal section can be created, and the ghost detection period can be expanded. When the second ghost remover detects a ghost, the first ghost remover does not generate a cancellation signal and has a constant tap gain, so that the first ghost remover generates a ghost. The cancel signal is
It will no longer mix into the ghost detection section of the second ghost removal section and cause interference.

(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 examples of the reference signals will be explained with reference to FIGS. 3 and 4. As shown in Fig. 3, the reference signal used in this device has an impulse waveform approximately in the center of one horizontal period, and a ghost detection section is set in a 24 μsee period from this impulse waveform. There is a method B2 which has an impulse waveform at a position earlier than the signal and sets a ghost detection section in a section after a 24 μsee period from this impulse waveform.

The ghost removal device performs H (described later) on two ghost removal units.

In the first boss removal section, when the reference signal A1 arrives, 24μsee 11 after this reference signal A1 is detected.
7] to detect whether there is a signal (ghost) similar to this reference signal A1. When a ghost is detected from the human input signal, the tap gain corresponding to the delay time from the reference signal A1 to the ghost is corrected to generate a cancellation signal. This cancellation signal is added to the original input signal with opposite polarity.

As a result, an output signal from which ghosts have been removed is obtained, but ghost detection is further performed, and if ghosts remain, the data in the tap gain memory is corrected again.

In the second 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 same manner as above, the tap gain is corrected in accordance with the delay time until the ghost, and a cancellation signal is generated.

Here, a problem arises when the second ghost removal section performs ghost detection while the first ghost removal section is performing a ghost removal operation.

For example, a case where a ghost Gl (with a delay of time td) as shown in FIG. 4 exists will be explained.

The ghost G1 is a ghost of the horizontal synchronization signal, and the first ghost removal unit that performs ghost detection using the reference signal A1 does not perform tap gain correction because there is no ghost due to the reference signal A1 within the detection interval. do not have. On the other hand, when the reference signal B1 arrives in the second ghost removal section, since a ghost due to the reference signal B1 exists within the detection section, the second ghost removal section corrects the tap gain and performs ghost removal processing based on the reference signal B1. Generates a cancel signal. This is because the ghost G2 of the reference signal B1 exists within the detection section of the second ghost removal section. This also removes the ghost component of the horizontal synchronization signal.

However, in the above case, the first ghost remover does not malfunction, does not perform tap gain correction, and the second ghost remover accurately generates a cancellation signal, but in an actual circuit, It is not always possible to obtain the ideal operation as described above.

For example, if the first ghost removal section determines that the ghost horizontal synchronization signal G1 is a ghost of the reference signal A1, an unnecessary tap gain will occur in the first ghost removal section. When such a situation occurs, the cancellation signal (for ghost horizontal synchronization signal cancellation) generated by the first ghost removal section mixes into the detection section of the second ghost removal section. Then, the second ghost removal section also erroneously determines that the mixed signal is a ghost, and further generates an unnecessary cancellation signal. Then, due to this cancel signal, the first cancel signal generator also performs erroneous ghost detection, and the first and second ghost removers interfere with each other.

Therefore, in the present invention, as shown in FIG. 1, a first ghost removal section 100 and a second ghost removal section 200 are used to cancel a ghost cancellation signal using a reference signal A1 and a reference signal B1, respectively. When the second boss removal section 200 performs ghost detection, a switch is added to the tap gain register 101 from the data register 104 so that the first ghost removal section 100 does not generate a cancellation signal. 10
- It is configured so that a certain fixed value is given through 5. That is, data from the tap gain memory 103 is cut off and a fixed value (for example, all zeros) is supplied instead.

FIG. 5 shows an example of rectangular wave-like reference signals AI and Bl used in an embodiment of the present invention. In an embodiment of the present invention, the reference signals A1 and 81 are a predetermined line (for example, No. 17 No. 1) of the vertical blanking interval of the television signal.
, and after P reference signals A1 continue, one reference signal B1 is inserted and transmitted.

A specific embodiment will be described below with reference to FIG. The human video signal is supplied to a subtracter 12 via a terminal 11 and also to a pulse width detector 21 . Subtractor 1
2 subtracts the ghost cancellation signal from the input video signal and outputs the result to the output terminal 13. The subtracter 12 also serves as part of the first ghost removal section 100 and a part of the second ghost removal section 200. The pulse width detector 21 detects the pulse width of the reference signal explained in FIG. 5, outputs a low level when the reference signal A1 arrives, generates a pulse when the reference signal B1 arrives, Its output is fed to the reset input of flywheel counter 22.

The flywheel counter 22 counts vertical synchronization pulses and is reset when the reference signal B1 is detected. The count value is set to P, and if there is a count of P+1-Q,
Performs a self-reset that generates its own gate pulse. This counter output is the first signal that the first reference signal A1 arrives at.
The level is high in the ~Pth field, and the level is low in the (P+1)th field. The counter output is supplied to the control gate generation circuit 23. The control gate generation circuit 23 counts the clock Cp in synchronization with the horizontal synchronizing pulse, and when the output from the counter 22 is at a low level, the clock Cp is counted over the area near the reference signal B1 as shown in FIG. A control gate signal S whose polarity is inverted is created.

Control day No. 815 S temporarily switches the tap gain of the first ghost removal section 100, which will be described later, to a fixed value.

1st. The second ghost removal unit 100, 200 will be explained.

This embodiment is of a feedback type, and the signal at the output terminal 13 is the first one. It is connected in parallel to each multiplier of the second ghost removal sections 100 and 200.

The first ghost removal unit 100 includes a transversal filter unit 111 in which adders and delay lines are alternately connected in series, the adder is further supplied with the output of a multiplier, and a tap that provides a tap gain to each multiplier. gain register 1゛O1;
It has a tap gain memory 103 that stores tap gains to be supplied to the tap gain register 101. Here, the output of the tap gain memory 103 is given to the tap gain register 101 via the switch 105.
When the control gate signal S becomes low level as shown in FIG. Ru. On the other hand, the second ghost removal section 200 basically has the same configuration as the first ghost removal section 100, and includes a transversal filter 211, a tap gain register 201, and a tap gain memory 203.

In this example, the second ghost removal unit 200 is configured such that the output data of the tap gain memory 203 is directly supplied to the tap gain register 201.

The tap gain memory 103 stores data for generating a cancellation signal when a ghost is detected based on the first reference signal A1, and the tap gain memory 203 stores data for generating a cancellation signal when a ghost is detected based on the second reference signal B1. Data for generating a cancel signal when detected is stored.

ml reference signal A1 as a reference and correct the data in the tap gain memory 103, the switch 36 connects the correlation calculator 34 and the tap gain memory 103 and uses the first reference signal B1 as a reference. When detecting a ghost and modifying the data in the tap gain memory 203, the switch 36 connects the correlation calculator 34 and the tap gain 1fI memory 203. When detecting a ghost, the signal at the output terminal 13 is supplied to the subtracter 31 and subtracted from the reference waveform from the reference waveform memory 32, and the subtracted output is input to the differentiator 33. If there is no residual ghost, the reference signal is canceled by the reference waveform, and the output of the subtracter 31 is zero; however, if a ghost exists, the output appears, is differentiated by the differentiator 33, and then is output to the correlation calculator [4]. is man-powered. Further, in the correlation calculator 34, the output of the subtracter 12 is inputted via a differentiator 35 to obtain a reference pulse for correlation calculation timing.

In the first ghost removal section 100, when the first reference signal arrives, its tap gain C(1) to C(M)
is controlled by the following algorithm.

In the second ghost removal section 200, when the second reference signal arrives, its tap gain C(1) to C(M)
is controlled by the following algorithm.

C is the corrected tap gain, α is a positive constant (k) number, co(k) is the initial value of the register, and '(k) is the output of the correlation calculator.

According to the ghost removal device configured as described above, the first ghost removal section 100 is connected to the second ghost removal section 2.
When ghost detection is performed with 00, switch 1
05 is switched to the data register 104 side,
Does not output cancel signal. Therefore, the second ghost removal unit 200 can detect the original ghost in the ghost detection section described in FIG. 4. If the first
If the second ghost remover 200 performs ghost detection while the ghost remover 100 continues to output the cancellation signal, if the first ghost remover 100 malfunctions, the second ghost remover 100 detects a ghost. Ghosts different from the original ghosts are mixed into the 200 ghost detection sections, causing mutual interference, but by doing as in this embodiment, stable ghost removal can be obtained.

FIG. 7 shows another embodiment of the present invention, and is an example in which the configuration of the first ghost removal section 100 is configured to generate a cancellation signal even for a ghost that exists before the reference signal. . Therefore, parts corresponding to the embodiment in FIG. 1 are given the same reference numerals as in FIG. The difference from the embodiment shown in FIG. 1 is the inside of the first ghost removal section 100.

That is, the subtracter 12 in FIG. 1 is divided into subtractors 12a and 12b, the transversal filter 111 is divided into transversal filters 111a and 111b, and similarly the tap gain register 101 and the tap gain memory 103 are divided into subtractors 12a and 12b.
．． It has a configuration in which the register 104 and the switch 105 are divided.

The output of the subtracter 12a is supplied to a delay circuit 112 and a transversal filter 111a. The transversal filter 111a has tap gains C(-1) to C(-
k) is given from tap gain register 101a. With transversal filter 111a? The canceled signal cancels the ghost component of the signal from the delay circuit 112 in the subtracter 113. The configuration of this part is of the feedforward type. The output of the subtracter 113 is supplied to the next subtracter 12b. The subtractor 12b is! Cancellation from the transversal filter 111b (removes the ghost component from the human power Ij using No. 5 and outputs it to the output terminal 13. For the transversal filter 111b, tap gain C from the tap gain register 101b (1) to C(N) are given Ij-.

Each tap gain register 101a, 101b has a tap gain memory 1 during normal ghost cancellation.
．． Tap gain data from 03a and 103b are provided via switches 105a and 105'b, respectively. However, while the second ghost removal section 200 is performing ghost detection, the switches 105a and 105b are controlled by the control gate signal S, and the corresponding tap gain registers 101a, 101b are set to fixed values, for example, initial values. give value. For this purpose, the second ghost removal part 2
00 will not detect unnecessary ghosts.

Delay circuit 21 provided in second ghost removal section 200
2 is for setting the ghost detection section shown in FIG. In the second ghost removal section 200, the tap gains C(N+1) to C(M) are modified as in the previous embodiment. The other parts are the same as the previous embodiment, and the first
The same reference numerals as those in the drawings are used to omit the explanation.

FIG. 8 shows yet another embodiment of the invention.

In this embodiment, when the first to third reference signals are transmitted as reference signals, ghosts in ghost detection sections set corresponding to each reference signal are detected, and cancellation signals for the ghosts in each section are sent. It is designed so that it can be obtained stably.

The difference between the embodiment in FIG. 7 and the embodiment in FIG.
The number of taps of the transversal filter section 211 of the ghost removal section 200 is increased, and a new tap gain C (Mal
) to C(L). Along with this, a tap gain register 213 and a tap gain memory 214 for providing tap gains C(Mal) to C(1,) are added. Furthermore, in order to correct the gain of the tap gain memory 214, the other tap gains C(Ni1) to C(M) are normally given when ghost detection is being performed in the assigned ghost detection section. In order to eliminate this inconvenience, the tap gains C(Ni1) to C(M) at this time are configured to be given as fixed values from the register 215 via the switch 216. Further, the second ghost removal unit 200 includes a tap gain memory 203 for storing a tap gain based on the result of ghost detection based on the second reference signal B1, and a tap gain memory 203 for storing a tap gain based on the result of ghost detection based on the second reference signal B1. Since a tap gain memory 214 for storing the tap gain based on the result of ghost detection is provided, a switch 36a for distributing correction data to each tap gain memory 203 and 214 is provided.

1st. Second and third reference signals AI, Bl.

For example, a reference signal as shown in FIG. 9 is used as C1, and ghost detection sections based on each reference signal can be set to different sections. Ghost detection using the first reference signal A1 is performed within a period T1 from the reference signal A1, ghost detection using the second reference signal B1 is performed within a period (T2-Tl) from the reference signal B1, and the third reference signal Ghost detection using signal C1 is based on reference signal C.
1 to period (T3-T2).

In this embodiment, when the tap gain of the second ghost remover 200 is modified, the first ghost remover 10
In addition to the operation of switching the tap gain of 0 to a fixed value, the second
When the gain of the tap gain memory 214 of the ghost remover 200 is modified, it is necessary to switch the output of the tap gain register 201 to a fixed value. To this end, control gate generator 23 also controls switch 216 . For this purpose, the control gate generator 23 includes the first .
Second. Third reference signals AI, Bl.

For example, control gate signals Sl and S2 as shown in FIG. 10 are generated so that the arrival of C1 can be identified.

By passing this signal through the logic circuitry, each switch 216.16. a and 105a.

105b is controlled. Now, if the fixed contacts of each switch are a, b, and c as shown, each switch 1
05a, 105b, and 216.16a may be switched to the fixed contact side as shown in the following table.

As a result, the fixed state and control state of each tap gain IG are summarized as shown in the following table.

As described above, the third tap gains C(Mal) to C(L
) are the first and second tap gains C(-1) to C(-k
), C(1) to C(N) are controlled without being affected.

In the above embodiment, the second goose removing section 200 and the metransversal filter 211 are of an integrated type.However, as shown in FIG. 11, a separate type may be used.

In FIG. 11, parts corresponding to those in the embodiment of FIG. 8 are given the same reference numerals. Transversal filter 21
1a, delay circuit 212a, tap gain register 201
, tap gain memory 203, switch 216 . The register 215 is a part that performs ghost detection based on the second reference signal B2 and obtains a cancellation signal. Further, the transversal filter 211b, the delay circuit 212b, the tap gain register 221, and the tap gain memory 223 are parts that detect a ghost based on the third reference signal and obtain a cancellation signal. Then, the canceled numbers obtained from each transnomous filter section 211a, 211b are as follows.
The signals are added by an adder 224 and supplied to a subtracter 12a to cancel ghosts.

In the above explanation, the input signal to each transversal filter is adjusted by a delay circuit so that the ghost detection sections do not overlap, but as shown in FIG. Even if the ghost detection sections of 200 and 200 are set to overlap, mutual interference will not occur. In this case, the precision of the delay circuit provided at the input end of the transversal filter can be relaxed, which may be convenient in terms of design.

As mentioned above, in a device that uses a plurality of reference signals to create a canceling signal, after convergence has been achieved to a certain extent and ghosts have been relatively reduced, mutual interference between the ghost removers tends to occur. It may be better to stop the operation of switching to a fixed value. In such a case, the switching operation to the fixed value may be stopped manually or with a timer, or by monitoring the total amount of tap gain. In this case, this can be realized by simple means such as turning off the control gate signal.

[Effects of the Invention] As described above, in the present invention, when a plurality of reference signals are used to obtain cancellation signals in a plurality of ghost removal sections, each ghost removal section generates a cancellation signal to eliminate other ghosts. It is possible to eliminate the negative influence of the removing section on ghost detection.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIGS. 2 to 2 are waveform diagrams for explaining a reference signal according to the present invention, and FIGS. FIGS. 9 and 10 are waveform diagrams showing other examples of the reference signal according to the present invention, and FIG. 11 is a circuit diagram showing another example 1 of the present invention. FIG. 12 is an explanatory diagram shown for explaining another example of circuit operation according to the present invention. 12.31... Subtractor, 21... Pulse width detector,
22... Flywheel counter, 23... Control gate generator, 32... Reference waveform memory, 33
゜35...Differentiator, 34...Correlation calculator, 36.1
05...Switch, 100,200...1st. Second
Ghost removal unit, 1t, z, 2o1... Yu/Tuburi j re-register, 102, 203... Yu/Tsubu Ri memory, 104... Data register, 111, 211...
...Transformer monkey filter section. Applicant's agent Patent attorney Niri Suzue Figure 3 Coast axillary area Mon-ichi-danki Figure 4 Figure 10
---------J"・200: 12 Coast Resurrection Mantle Figure 11 Figure 17 T4-1 Figure 12

Claims (1)

[Claims] A transversal filter, a tap gain register storing the tap gain of the transversal filter,
A tap gain memory that supplies data to the tap gain register, gain modification means that modifies the data in the tap gain memory when a reference signal arrives, and a cancellation signal output from the transversal filter to eliminate ghosts in the input signal. In the ghost removal device, the ghost removal unit includes a first ghost removal unit as the ghost removal unit, and a second ghost removal unit that receives the ghost removal output of the first ghost removal unit as an input. a first reference signal and a second reference signal whose arrival timing is different from that of the first reference signal; Means is provided for switching the contents of the tap gain register of the first ghost removal unit to a predetermined fixed value during a period in which an operation is performed to correct the data in the tap gain memory based on the above. A ghost removal device characterized by: