JPS58201476A - Ghost eliminating device - Google Patents

Abstract

PURPOSE:To optimize the switching of a transversal filter, by A/D converting a small section including a front ridge of a vertical synchronizing signal and its ghost waveform, processing them digitally and detecting the time location of the ghost component accurately. CONSTITUTION:The waveform of a small section (27musec) including the front ridge of the vertical synchronizing signal and its ghost waveform is sampled at a clock pulse of (b), and A/D-converted. The difference between the n-th and the (n-1)th waveform is calculated at a differential circuit 8 and the result is stored in an RAM 9. The calculation of Xk.Xk+1 is done up to the address (m), where Xk is a data at the address K of the RAM 9, and the result is accumulated and stored in an RAM 2. The values m, I are selected suitably in response to a ghost delay time T. The difference of the peaks at the addresses P and Q as the result of operation corresponds to the ghost delay time. Thus, the tap of the transversal filter is switched.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ghost removal device for a television receiver, and a ghost removal device using a transpanal filter.

The ghost phenomenon, which is a problem in the reception of television receivers, occurs because the direct waves of television broadcasting and the reflected waves from buildings, etc. are received directly.
, to remove the video signal obtained by detecting the received wave, is it a correction signal with the same amplitude as the ghost component contained in it? It is sufficient to generate the ghost signal tVC for a time of 151115 minutes and calculate this signal from the video signal.

Various ghost removal devices based on the principle of prayer have been proposed in the past, but one in particular that uses a transperch filter for slow generation has been brought into close-up. In principle, a transpertil filter is composed of a combination of a charge transfer type shift register such as ±COD having a 7JD arithmetic function and a = number of multipliers for switching the tap gain of this shift register. 8 is added to the tap gain and delay addition is performed, and when used as a ghost removal device, it has the advantage that two parameters, the amplitude and delay time of the on-plane signal, can be controlled simultaneously.

FIG. 1 shows the schematic configuration of a ghost ghost removal device using a transpercent filter.

In other words, the mismatched video words derived from the video detection circuit of a television receiver become transvernal filters (
1) and on the other hand directly introduced into the subtractor (21)
,ru. The output of this subtracter (2) is the ghost detection circuit t3.
The time position and amplitude information of the residual ghost H are detected for each person. Then, a tap gain switching circuit (4) determines the tap gain of the transvernal filter (1), that is, each multiplier of the above-mentioned ± multiplier, based on this dropout output. Therefore, the signal coming out of the transpanal filter peak finally waits for the delay time and amplitude to decrease by 1j9f, and as a result, the signal from the subtractor (2)
After removing the ghost component from Q, the combined video signal is derived.
．． This is the reason.

The folding ghost removal device VC is used to accurately detect the time position of the ghost component in the transmitted image, which is derived from the subtracter [2J, and calculates the corresponding tap gain (transformer) of each downstream stage. (of the barzal filter) must be switched. To keep this in mind, conventional ghost detection circuits (31
The leading edge of the vertical synchronization signal in the composite video signal was used as a time reference to detect the time position and S width information of the ghost component. However, the leading edge is subject to transmission distortion,
If noise or the like is mixed in, the time position cannot be detected accurately, and the tap gain of each stage will be set incorrectly.

Therefore, the present invention has been made by focusing on the folding point VC, and the details thereof will be explained below.

Figure 2 shows a 14m ghost removal device using Shukan #J.
An example is shown, where fil is a transpanal filter,
(2) is a subtracter, (3) is a ghost detection circuit, and (4) is a tag gain switching circuit, and except for the detection circuit t3J, the other configurations are the same as in FIG.

In the ghost detection circuit (32), (5) is a vertical synchronization signal part extraction circuit, and this circuit is connected to the subtracter (2).
A small section (27μ5ec) (see Fig. 6 (~)) including the leading edge of the vertical synchronization signal in the composite video signal derived from is extracted, and the output signal is sent to the secondary A/D conversion circuit (7). give.

The A/Di switching time ti3i71 has an IQ of 7 MHz (D
') Cy is numbered with 7 pulses (Fig. 6(b)), and the amplitude values corresponding to each chimpling time are converted into a 6-bit digital signal VC and then sent to the next difference circuit (81V
Send C.

This differential circuit (8) operates according to the primary clock pulse (b) VC, and the output of the #JfA/D'i switching circuit (7) is connected to the n-1st and nth clocks of 7. The circuit calculates data corresponding to the barley (binary numbers) one after another and sends each data to the next first RAM (91).In the seventh step, the difference circuit (8) is composed of a shift register, an inverter, a full adder, etc. Ffc is applied, and the above calculation is performed in addition to the addition operation using the open number of 2.

@1st RAMf9) is the above-mentioned clock pulse (b)
By the address designation input with . Go.

When the data based on the vertical synchronizing signal section VC of the field formed in this manner is stored in the first RAM (9), the microprocessor 1111 inputs the address designation input +
1(l) and sequentially store data from the RAM+91, and perform an autocorrelation calculation on each data in the multiplication circuit 02 and the cumulative addition circuit 03 as follows.

That is, the data in the first RAM 191 is X.
If it is expressed as k, then the microprocessor συ written in
■ is the multiplication m8 (O or natural number) selected as described below.
The results of the seven multiplications are cumulatively added in the cumulative addition circuit G3. Therefore, the cumulative 1
1 [YI is Y■ ~ OxXIWO ・Xk-) - I (where n is the maximum address, k<n,
m+t<n), and this operation is performed every ryQ, 1.2, -.

Therefore, for example, if n12m, 0≦5m10<I
If ≦m, the cumulative basket Yo at the time of ryQ is Yo−Xo
・Xa+X1−X+ +−−−−+Xm−X1, rw
When l, YlyXo -X+ +X1-X2 +---
+Xm -X 1+mtoyz, hereafter FI5] 1cL.

te r -mノlhYm-X o -Xm +X 1-
X1-1-m+...-+Xm-X2m. And each cumulative 1i! Yb, that is, the correlation calculation result is stored from address control 141VC to each number Jti[:son0 address 11@] of the second RA Mt151.

Among these, III and I were selected as described above, but these can be selected appropriately by predicting the ghost delay time (° C.) shown in FIG.

If the correlation calculation results of Koma2RAMffM are stored in this way, as shown schematically in FIG.
In the 0@ area of Mf15, large value data based on the multiplication of the peak parts (P) in FIG. 5(c) is stored, and the nei address (beak part P)(0
The data of the next largest value resulting from the multiplication between them will be stored. Even if the starting position of the A/D converter of the vertical synchronizing signal edge in the A/D converter circuit (7) is slightly shifted, the above construction address will always be as shown in Figure 5 with the VCO address as the reference position. Address 2 corresponding to the ghost delay time (f') is represented.

Therefore, the 5 stages l of the transpanal filter B1)
! al-man 2 correspond to each address of RAMIIS, 0 of 7
What is the tap gain of each stage of the above transpanal filter depending on the data of each address after the address? The tap gain switching circuit (4) is controlled by the microprocessor unVC. In this way,
Since the data in the second RAM (151) accurately corresponds to the time position and amplitude of the ghost component, this operation is repeated for each field, and the tap gain of each stage of the transpanal filter fl+ is adjusted to the ghost component. This is repeated until the optimum value is reached.As a result, the subtracter (2) removes the ghost component and derives a +/− line video signal.

The above-mentioned ghost removal device of the present invention extracts the vertical timing signal 5j @ edge of the combined video signal, converts it into AD and converts it, and calculates the difference between the digital signal obtained by the person/D conversion. Then, an autocorrelation calculation is performed on the difference data, and the tap gain of each stage of the transpanal filter is switched based on the result of this calculation, so the tap gain of each stage is changed to each ghost component. It can be set as appropriate depending on the situation.

Is the data obtained from the above-mentioned circle from the t1 vertical signal section?
Since the memory is stored once, this data is read once and the above-mentioned correlation calculation is performed, it is possible to perform the above-mentioned correlation calculation quickly, and there is also the advantage that it can be realized at low cost.

Furthermore, each circuit in the ghost detection circuit (3) except for the vertical synchronization signal part extraction circuit 15) is all done with two lines of digital processing, so when this circuit (3) is constructed from a 1#''-sized IC, It is particularly suitable for VC.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a schematic configuration of a ghost removal device using a transpernal filter, Fig. 2 is a diagram showing an example of a ghost detection circuit for T: valve, and Fig. 3 is an explanation of its operation waveform factor. , Figure 4 is a diagram illustrating the data storage state of the second RAM.

Claims (1)

[Claims] The television slimming video signal is passed through a transpertil filter, and a ghost correction signal is created using VC2.
Combine this correction signal with the above-mentioned composite video signal.
Is it a ghost ingredient? The removing device extracts a small section including the leading edge of the vertical synchronizing signal and the ghost waveform 2 of the leading edge of cough from the protection video signal, converts it into A and 'D, and performs full A/D conversion. The data is read out in a predetermined order from this memory, and the autocorrelation calculation is performed sequentially, and each calculation result Vq: Core The ghost filter device is configured to switch the tap gain of each stage of the transpertil filter.