JPS63190416A - Ghost eliminating device - Google Patents

Abstract

PURPOSE:To keep the output amplitude constant by using the result of calculation by a tap coefficient obtained for ghost elimination so as to apply output amplitude control. CONSTITUTION:A computing element 4 applies correlation operation between an input signal waveform and an error signal waveform between an output signal waveform fed back from an adder 6 and a reference signal waveform to detect ghost so as to decide tap coefficients C-M-CO-CN of multipliers T-M-TO-TN controlling the gain of each tape. The adder 8 takes the sum of outputs from each tap subject to gain adjustment by using the tap coefficients C-M-CO-CN. The tap coefficients C-M-CO-CN are corrected and decided so as to minimize the error signal waveform between the reference signal waveform and the input signal waveform. Then, the video signal subject to ghost elimination is applied from the adder 6 to the amplifier 7. The amplifier 7 uses the tap coefficients C-M-CO-CN for the calculation and is subject to gain control by a CPU 5 to make the video signal amplitude outputted from an output terminal 8 constant and a video signal whose ghost is eliminated and having a constant amplitude is obtained at the output terminal 8.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ghost removal device for removing ghosts generated in a television signal transmission path.

2. Description of the Related Art Conventionally, as a ghost removal device that uses a transversal filter to remove ghosts generated in a transmission path of a television signal, for example, there is a ghost removal device that uses a transversal filter to remove ghosts generated in a television signal transmission path.
l, 37. l1kL2 (1983) PP124~P
There is P132.

FIG. 2 is a block diagram of a ghost removal device using this conventional transversal filter, in which 10 is an input terminal;
11 is a tapped delay line, 12 is a multiplier, 13 is an arithmetic unit,
14 is an adder, and 15 is an output terminal.

The operation will be explained below.

A video signal is inputted from an input terminal 10, and then inputted to a tapped delay line 11 and an arithmetic unit 13. The tapped delay line 11 has M+N+1 taps, and each tap has T-I to T of a multiplier 12 that adjusts each gain.

~T, multipliers correspond. The arithmetic unit 13 includes a multiplier T- which controls the gain of each tap by calculating the correlation between the input signal waveform and the error signal waveform between the output signal waveform fed back from the adder 14 and the reference signal waveform for ghost detection. Tap coefficient C-,
-Determine Co-CM. The adder l4 sums up the outputs from each tap whose gain has been adjusted by the tap coefficients C-M-Co-CN.

The tap coefficients C-8 to C, -CM are modified and determined so that the error signal waveform between the reference signal waveform and the human input signal waveform is minimized. A video signal waveform from which ghosts have been removed is obtained from the output terminal 15.

Problems to be Solved by the Invention In television receivers, automatic gain adjustment is performed in order to keep the brightness and contrast of the projected image constant, and the amplitude of the video signal input to the ghost removal device is adjusted. is kept approximately constant (generally I VP-P ). Therefore, the amplitude of the video signal from which the ghost has been removed by the ghost removal device changes depending on the state of the ghost, resulting in a problem in that the brightness and contrast of the image displayed on the television receiver change.

Means for Solving the Problems In order to solve the above problems, the ghost removal device of the present invention uses the tap coefficients of the transversal filter to calculate the amplitude of the video signal from which ghosts have been removed using the transversal filter. Automatic gain control is performed based on the calculation results.

Function: The present invention performs automatic gain control of the amplitude of a signal from which ghosts have been removed based on the calculation results using tap coefficients of a transversal filter for ghost removal.

Example Below, regarding a ghost removal device according to an example of the present invention,
This will be explained with reference to the drawings.

FIG. 1 is a configuration diagram of a ghost removal device using a transversal filter according to the present invention, where ■ is an input terminal, 2-tapped delay line, 3 is a multiplier, 4 is an arithmetic unit, and 5 is a CPU.
, 6 is an adder, 7 is an amplifier, 8 is an output terminal, and 9 is a portion of the conventional transversal filter shown in FIG.

The operation will be explained below.

The portion indicated by the conventional transversal filter 9 performs the same operation as described in the related art. A video signal is input from an input terminal l, and is input to a tapped delay line 2 and an arithmetic unit 4. M+N+ for tapped delay line
There is one tap, and each tap corresponds to multipliers T-i to T0 to T9 of the multiplier 3 that adjust the respective gains. The arithmetic unit 4 includes a multiplier T- which controls the gain of each tap by calculating the correlation between the input signal waveform and the error signal waveform between the output signal waveform fed back from the adder 6 and the reference signal waveform for ghost detection. Tap coefficients C-M to C0 to C8 of A to T0 to T are determined.

In the adder 6, the tap coefficients C-i~Co''Cs
The sum of the outputs from each tap whose gain has been adjusted by is calculated. The tap coefficients C□~Co''Cs are modified and determined so that the miscalculated signal waveform between the reference signal waveform and the input signal waveform is minimized.Then, the ghost-removed video signal is added from the adder 6 to the amplifier 7. The amplifier 7 calculates the tap coefficients 01 to co to C, and outputs an image from the output terminal 8.

In this embodiment, the arithmetic unit 4 and CPU 5 are separated, but
Even if it is implemented with one CPU, the same operation will occur. In addition, instead of controlling the gain of the summing amplifier 6, the coefficient 00 of the multiplier T0 of the main tap of the multiplier 3, which becomes the desired signal after ghost removal, is set to the tap coefficients 01 to 00 to C8 at the time of ghost removal.
The amplitude of the video signal output to the output terminal 8 can be kept constant by controlling based on the calculation result of the CPU 5 using the .

Effects of the Invention As described above, according to the ghost removal device of the present invention, the output amplitude can be kept constant by controlling the output amplitude based on the result of calculation using the tap coefficient obtained for ghost removal. This allows the brightness and contrast of the image displayed on the television receiver to be kept constant.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a ghost removal device according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a conventional ghost removal device. 1... Input terminal, 2... Delay line with tap, 3... Multiplier, 4... Arithmetic unit, 5
...CPU, 6...Adder, 7...
...Amplifier, 8...Output terminal. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 2

Claims (2)

[Claims] (1) A ghost removal device characterized in that the amplitude of a video signal from which ghosts have been removed using a transversal filter is automatically gain controlled based on a calculation result using tap coefficients of the transversal filter. (2) Ghost removal according to claim (1), which performs main tap coefficient control based on the calculation result using the tap coefficients of the transversal filter, and performs automatic gain control of the amplitude of the ghost-removed video signal. Device.