KR970008096B1 - Ghost displaying apparatus - Google Patents

Abstract

an A/D converter(10) converting an analog image signal including a ghost cancel GCR signal to a digital signal; a FIFO part(20) extracting the ghost cancel GCR signal from the digital image signal converted by the A/D converter(10); a memory means(100) where a comparison GCR signal including a ghost; a reference signal storing table(30) storing a reference GCR signal from a receiving part; a CPU(40) reading the comparison GCR signal from the memory means(100) and generating a pseudo filter coefficient by performing a channel characterization operation comparing the comparison GCR signal with the reference GCR signal; a filter part(50) which outputs the undistorted ghost cancel GCR signal in case of no ghost and otherwise, outputs a distortion state signal of the distorted ghost cancel GCR signal by performing the filtering operation; and a D/A converter(60) making the ghost component displayed in a TV screen by converting the output signal from the filter part(50) to an analog signal.

Description

Ghost display

1 is a block diagram of a conventional ghost removal device,

2 is a block diagram of a ghost display device according to the present invention;

3 is a waveform diagram of a comparison GCR signal for displaying ghosts on a TV screen.

* Explanation of symbols for the main parts of the drawings

10: A / D conversion unit 20: FIFO unit

30: reference signal storage table 40: CPU

50: filter 60: D / A converter

70: synchronous separation and clock generator 100: ROM

110: switching unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ghost display device, and more particularly, to displaying a ghost mixed with an input signal on a television screen so that a viewer can visually check how much ghost is included in the input signal. Relates to a device.

In general, the ghost is reflected by the impedance matching of the line is not made by the terrain of buildings, mountains, etc. while the television signal transmitted from the broadcasting station reaches the television receiver through the air or the line to form a multi-path to the receiver It refers to a phenomenon in which reflected signals appear in addition to the signal, and a ghost removal device is used to remove such ghosts.

The broadcasting station transmits a ghost cancel reference signal (GCR) to some sections of the television signal, that is, the vertical blanking section, and the ghost cancellation apparatus of the television receiver on the receiving side has the same reference GCR signal. . Ghost Rejection GCR signals are received without distortion in the absence of ghosts, but in response to ghosts, distortion is generated. Therefore, by comparing the transmitted ghost elimination GCR signal with the reference GCR signal, a channel characterization operation is performed to calculate how distorted the received ghost elimination GCR signal signal is obtained and to obtain channel characteristics of the transmission path, and then inverse characteristics of the transmission channel. Passing through the filter can correct the distortion of the signal.

1 shows the basic configuration of such a conventional ghost removal apparatus. As shown in the drawing, a conventional ghost elimination device includes an analog / digital (A / D) converter 10 for converting a video signal transmitted from a broadcasting station into a digital signal, and a ghost elimination GCR inserted in the digitally converted video signal. A first-in first-out (FIFO) unit 20 for extracting a signal, a synchronous separation and clock generator 70 for separating a synchronous signal from an input video signal, and generating a clock at a constant speed, and a reference GCR signal at a receiving side. The reference signal storage table 30 to be stored and the ghost removal GCR signal extracted from the FIFO unit 20 and the reference GCR signal stored in the reference signal storage table 30 are compared to each other. The CPU 40 calculates filter coefficients capable of compensating for distortion of the signal generated in the transmission path by detecting the characteristic, and the distortion of the signal generated in the transmission path is compensated using the filter coefficient and the image signal of the CPU 40. doing A filter unit 50 and a digital / analog (D / A) converter 60 for converting the output of the filter unit 50 into an analog signal are included.

Referring to the operation of the conventional ghost removing device of the above-described configuration, the video signal transmitted from the broadcasting station is input to the A / D converter 10 and the synchronous separation and clock generator 70. The A / D converter 10 converts the input video signal into a digital video signal and provides the converted video signal to the FOFO 20.

The synchronous separation and clock generator 70 separates the synchronous signal from the video signal and controls the FIFO 20 during the vertical blanking pulse period to remove the ghost in the digital video signal converted by the A / D converter 10. The ingredients are extracted and stored. The stored ghost removal GCR signal is provided to the CPU 40.

Meanwhile, the CPU 40 performs an operation of adding or subtracting the extracted GCR signal in a specific order to remove the color burst signal, the horizontal synchronization signal, and the noise from the ghost removal GCR signal component provided by the FIFO 20. This operation leaves only the pure ghost cancellation GCR signal with the color burst and horizontal sync signal removed.

Then, the ghost cancellation GCR signal is correlated with the reference GCR signal stored in the reference signal storage table 30 to generate a correlation peak value in one place.

At this time, if the correlation is taken due to the characteristics of the reference signal, one peak value is obtained and the correlation value is "0". Therefore, the place where the maximum value occurs by taking correlation is the place where the ghost elimination GCR signal and the reference GCR signal of the receiver exactly match. And this position is set as the reference position of ghost removal. When the ghost removal GCR signal passes through the filter section 50, the filter coefficients are calculated and transmitted to the filter section 50 so as to be a reference GCR signal (ie, a signal without ghosts) of the receiver. The distortion-compensated GCR signal is provided to the D / A converter 60 to be output as an analog signal and displayed on the TV screen.

However, although the above-described conventional ghost removal apparatus can remove ghosts, it does not have a function of confirming how much ghosts are present in the video signal transmitted from the broadcasting station and showing ghosts present in the input signal.

Therefore, an object of the present invention is to provide a ghost display device that enables a viewer to visually know the ghost state of a video signal currently input by displaying a ghost present in an input video signal on a display screen.

According to the present invention for achieving the above object, an A / D converter for converting an analog video signal including a ghost removal GCR signal transmitted from a broadcasting station through a transmission path into a digital signal, and the conversion by the A / D converter A FIFO section for extracting the ghost removal GCR signal from the digital video signal, a memory means for storing a comparison GCR signal including a predetermined ghost, a reference signal storage table for storing a reference GCR signal at a receiving side, and ghost display A CPU for reading out the comparison GCR signal from the memory means and performing a channel characterization operation for comparing the read comparison GCR signal with the reference GCR signal provided from the reference signal storage table to generate a pseudo filter coefficient; A phase output from the FIFI unit according to the pseudo filter coefficient from the CPC A filter unit for performing a filtering operation on the ghost elimination GCR signal to output an undistorted ghost elimination GCR signal when there is no ghost, and to output a distortion state signal of the ghost elimination GCR signal which causes distortion when there is ghost; And a D / A converter configured to convert a signal output from the filter into an analog signal so that a ghost component is displayed on the TV screen.

Hereinafter, an embodiment of a ghost display device according to the present invention will be described in detail with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout.

2 is a block diagram of a ghost display device according to the present invention. As illustrated, the ghost display device of the present invention includes an A / D converter 10, an FIF unit 20, a synchronization signal and clock generator 70, a reference signal storage table 30, a CPU 40, The filter unit 50 includes a D / A converter 60, a ROM 100, and a switching unit 11.

In the same manner as described above, in the normal ghost removal mode, the A / D converter 10 converts a video signal transmitted from a broadcasting station into a digital signal and provides the digitally converted video signal to the FIFO unit 20. do.

The synchronizing signal and clock generator 70 separates the vertical synchronizing signal from the video signal transmitted from the broadcasting station, generates a clock signal having a constant speed from the separated synchronizing signal, and provides it to the FIFO unit 20. This clock signal extracts only the line signal carrying the ghost removal GCR signal from the digital video signal converted by the A / D converter 10 to be stored in the FIFO unit 20. The ghost removal GCR signal stored in the FIFO section 20 is provided to the CPU 40.

On the other hand, the reference signal storage table 30 stores a reference GCR signal on the receiving side, and the reference GCR signal is provided to the CPU 40.

The CPU 40 compares the ghost elimination GCR signal provided from the FIFO 20 with the reference GCR signal provided from the reference signal storage table 30 to detect the characteristics of the channel through which the television signal has been transmitted through the transmission line, Calculate filter coefficients to compensate for signal distortion. This calculated filter coefficient is provided to the filter unit 50.

The filter unit 50 filters the input image signal output from the A / D conversion unit 10 according to the filter coefficient provided from the CPU 40 to convert the image signal from which ghost is removed through the D / A converter 60. You can print it on the screen.

However, when the ghost display mode according to the present invention is selected, the ghost elimination GCR signal output from the FIFO unit 20 is provided to the filter unit 50 by the switching operation of the switching unit 110.

Meanwhile, the ROM 100 stores a comparison GCR signal including ghost as shown in FIG. 3, and the comparison GCR signal is used as a ghost removal GCR signal provided from the FIFO unit 20 in ghost removal mode. do. This comparison GCR signal is read by the CPU 40 in accordance with the ghost display mode.

In response to the ghost display mode, the CPU 40 performs a channel characterization operation for comparing the comparison GCR signal read from the ROM 100 with the reference GCR signal provided from the reference signal storage table 30 to perform the filter unit 50. Calculate the filter coefficients to be used in. This filter coefficient is provided to the filter unit 60 as a pseudo filter coefficient.

Accordingly, the filter unit 60 performs a filtering operation on the ghost removal GCR signal provided from the FIFO 20 according to the pseudo filter coefficient provided from the CPU 40. As a result, the filter unit 60 shows the state of the transmitted ghost removal GCR signal that is not distorted when there is no ghost with respect to the input video signal, but when the ghost is present, It is output as a distortion state. The output of the filter unit 50 is converted into an analog signal through the D / A converter 60 and displayed on the TV screen.

As described above, the ghost display device according to the present invention clearly shows the ghost included in the video signal input on the TV screen, so that the viewer can know the degree of ghost presence, and also the antenna in the direction of less ghost The operation will reduce ghosts.

Claims (1)

A ghost display device for displaying a ghost on a TV screen, comprising: an A / D converter (10) for converting an analog video signal including a ghost removal GCR signal transmitted from a broadcasting station through a transmission path into a digital signal; A FIFO unit 20 for extracting the ghost removal GCR signal from the digital video signal converted by the A / D converter 10; Memory means (100) storing a comparison GCR signal including a predetermined ghost; A reference signal storage table 30 for storing a reference GCR signal at the receiving side; Read the comparison GCR signal from the memory means 100 for ghost display, and perform a channel characterization operation to compare the read comparison GCR signal with the reference GCR signal provided from the reference signal storage table 30. A CPU 40 for generating a pseudo filter coefficient; By performing a filtering operation on the ghost elimination GCR signal output from the FIFI unit 20 according to the pseudo filter coefficient from the CPU 40, when there is no ghost, an undistorted ghost elimination GCR signal is output, and ghost A filter unit 50 for outputting a distortion state signal of the ghost elimination GCR signal which causes distortion when there is a corresponding signal; And an A / D converter (60) for converting a signal output from the filter unit (50) into an analog signal so that a ghost component is displayed on the TV screen.