KR960016564B1 - Adaptive ghost cancelling apparatus - Google Patents

Abstract

the first filtering means(10) to perform an FIR(Finite Impulse Response) filtering; a control means(30) to control the center tap of the first filtering means(10) automatically by generating a control signal; and the second filtering means(20) to perform an IIR(Infinite Impulse Response) filtering to remove a long ghost as to the input video signal by the second filtering of the first-filtered video signal and by a feedback of the second-filtered signal.

Description

Adaptive Ghost Eliminator

1 is a block diagram of an adaptive ghost removing device according to a preferred embodiment of the present invention.

2A, B, and C are diagrams showing the position of a center tap of a FIR (Finit Impulse Response) filter according to a channel characterization result.

* Explanation of symbols for main parts of the drawings

10: first filtering means 20: second filtering means

30: control means.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ghost removal device in a high definition image processing device (HDTV: High Definition TV), in particular a finite impulse response (FIR) filter and an infinite shock response (IIR). The present invention relates to an adaptive ghost elimination device suitable for adaptively removing ghosts using an Infinite Impulse Response filter.

As is well known, the ghost eliminator is for eliminating ghosts in which TV screens are displayed in double or triple multiple images. Ghost is a phenomenon caused by the reflection of the reflected wave reflected by a mountain, a building, etc. received from the transmitting side later than the direct wave. Such ghosts can be removed using a GCR (Ghost Cancellation Reference) signal which is inserted into a VBI (Vertical Blanking Interval) line and transmitted by a broadcasting station. That is, when the distortion characteristic is detected by channel characterization that calculates how much the received signal is distorted by comparing the received GCR signal with the GCR signal possessed by the receiver, the receiving side passes through a filter having the inverse characteristic of the distortion characteristic. The ghost will be removed.

Conventional ghost elimination device has the inverse characteristic of FIR filter and IIR filter cascaded, pre-ghost elimination and waveform equalization through FIR filter, and long through IIR filter. ) Remove ghost. However, the FIR filter used in these ghost eliminators has a fixed center tap position so that the ghost can be sufficiently removed if the pre-ghost present in the received signal is far from the main peak. There was no problem.

Accordingly, an object of the present invention is to provide an adaptive ghost removal apparatus that can adaptively adjust the position of the center tap of the FIR filter according to the magnitude and position of the ghost in the received signal and the degree of necessity of waveform equalization. There is.

In order to achieve the above object, the present invention, in the ghost removing apparatus of the high-definition video signal processing system for removing ghosts appearing in the playback image displayed by the reflected wave signal is applied together with the direct wave signal of the received input video signal, First filtering means for performing finite shock response filtering to perform line ghost removal and waveform equalization by performing linear phase filtering on the received input video signal; On the basis of the channel characterization processing result signal for the ghost included in the input video signal, when waveform equalization is not required, a control signal is generated so that the center tap of the first filtering means is assigned to the front part, and When the line ghost is generated, a control signal for allocating the center tap to be close to the position where the sun ghost is generated is generated. When waveform equalization is required, the control signal is generated such that the center tap is allocated to the center. 1 control means for automatically adjusting the position of the center tap of the filtering means; Long filtering the first filtered video signal output from the first filtering means by a predetermined transfer function and linearly combining the second filtered signal with a current input value. Provided is an adaptive ghost removal device comprising second filtering means for performing infinite impact filtering to remove ghosts.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an adaptive ghost elimination device according to a preferred embodiment of the present invention, comprising: first filtering means 10 for linear phase filtering an input signal X (n) applied for ghost elimination; The second filtering means 20 for filtering by linearly combining the current signal and the previously inputted value with respect to the signal output from the first filtering means 10, and the channel characterization processing result signal for the received signal is applied The control means 30 for outputting a signal tp for controlling the position of the center tap of the first filtering means 10.

Here, the first filtering means 10 is a FIR filter that performs finite shock response filtering, and the second filtering means uses the signal output from the first filtering means 10 as one input signal for linear coupling described above. The adder 21 to add and the signal output from the adder 21 are filtered by a predetermined transfer function H (z) and output to another input signal of the adder 21 as a filter (F1 (22)). It is an IIR filter for performing infinite shock response filtering.

FIG. 2A shows an example where the channel characterization result waveform equalizer is not required, FIG. 2B shows an example when the channel characterization result ghost is present, and FIG. 2C shows an example when the channel characterization result waveform equalizer is needed.

First, the adaptive ghost elimination device according to the present invention is to more effectively perform ghost cancellation for waveform equalization and pre-ghosting performed in the FIR filter, and the received signal as described above in the channel characterization calculation circuit (not shown). As a result of detecting the degree of distortion, as shown in FIG. 2A as an example, if it is determined that waveform equalization is not necessary for the line ghost, the control means 30 outputs a corresponding result signal.

Accordingly, in the control means 30, the position tp of the center tap during FIR filtering performed by the first filtering means 10 by a signal applied from a channel characterization calculation circuit (not shown) is shown in FIG. 2A as an example. As you can see, it is automatically controlled to be allocated earlier. Accordingly, the first filtering means 10 performs finite shock response filtering on the X (n) signal applied by the center tap located at the front portion and outputs the finite shock response as shown in FIG. 2A.

However, when the sun ghost is generated as shown in FIG. 2B as an example by the channel characterization calculation circuit (not shown), the control means 30 selects the center tap of the first filtering means 10. Control to be allocated later in the event. Accordingly, the first filtering means 10 outputs a waveform as shown in FIG. 2B.

Further, when the resultant signal is applied by the channel characterization calculation circuit as an example where waveform equalization is required as shown in FIG. 2C, the control means 30 assigns the center tap of the first filtering means 10 to the center. Control, and the first filtering means 10 outputs as shown in FIG. 2C. The second filtering means 20 uses the transfer function H (z) at the filter 22 with respect to the signal output from the first filtering means 10 through the adder 21 and the previously output signal. By repeating the process of linearly combining the processed and fed back signal, infinite shock response filtering is performed, thereby eliminating long ghost for the received signal.

In other words, according to the ghost elimination device according to the present invention, in performing a finite shock response filter process for removing waveform equalization and line ghost for a ghost received by a linear phase characteristic, the degree of distortion of the received signal By adjusting the position of the center tap for finite shock response filtering according to the resultant signal through channel characterization process, the more efficient waveform equalization and line ghost are eliminated.

That is, when the result of the channel characterization process does not require waveform equalization, the center tap control process is performed to control the center tap of the first filtering means 10 to be allocated to the front portion through the control means 30. In addition, when the channel characterization process results in the presence of the sun ghost, the control of the center tap for controlling the position of the center tap of the first filtering means 10 to be close to the point of the sun ghost through the control means 30 Perform the process. As shown in FIG. 2B, since the sun ghost is generated at the rear end, the center tab is controlled to be located at the rear part. If the result of the channel characterization process requires waveform equalization, the control means 30 performs a center tap control process for controlling the center tap of the first filtering means 10 to be allocated to the center.

Therefore, the finite impact response filtered signal is subjected to the infinite shock filtering process through the second filtering means 20.

As described above, the present invention has an advantage of more efficient preghosting and waveform equalization by adaptively adjusting the position of the center tap by the channel characterization result signal during finite shock filtering at the time of ghost removal.

Claims (1)

A ghost removing apparatus of a high quality video signal processing system for removing ghosts displayed on a reproduced image displayed by a reflected wave signal applied together with a direct wave signal of a received input video signal, the linear phase with respect to the received input video signal First filtering means (10) for performing finite impact response filtering for pre-ghost elimination and waveform equalization by performing filtering; On the basis of the channel characterization processing result signal for the ghost included in the input video signal, when waveform equalization is not necessary, a control signal is generated so that the center tap of the first filtering means 10 is assigned to the front part, and the input is performed. When the ghost is generated in the video signal, a control signal for allocating the center tap to the position where the ghost is generated is generated. When waveform equalization is required, the control signal is generated to generate the center tap at the center. Control means 30 for automatically adjusting the position of the center tap of the first filtering means (10); Input filtering by linearly combining the first filtered video signal output from the upper first filtering means 10 by a predetermined transfer function and feeding back the second filtered signal to the currently input value. An adaptive ghost elimination device comprising a second filtering means (20) for performing infinite shock filtering to remove long ghost for a signal.