KR0150970B1 - On-screen display location control circuit in ghost canceller - Google Patents

Abstract

The present invention relates to an OSD position control circuit for preventing the position change of the OSD display caused by the delay of the ghost cancellation filter in the ghost eliminator.

The present invention eliminates the change in the position of the OSD character after ghost removal by detecting the presence of a synchronous signal in an input signal that is not ghost removed and separating the horizontal / vertical synchronous signal from the ghost removed signal in the signal processing including ghost. A stable synchronization signal can be obtained.

Description

On Screen Display Position Control Circuit in Ghost Eliminator

1 is a simple block diagram of a conventional ghost eliminator.

2 is a detailed block diagram of the ghost elimination circuit of FIG.

FIG. 3 is a block diagram schematically illustrating a transverse filter of the ghost removing unit of FIG. 2. FIG.

4 shows an embodiment of OSD position change in a ghost eliminator.

5 is a simple block diagram of an on screen display position control circuit in a ghost eliminator.

* Explanation of symbols for main parts of the drawings

20: Tuner and intermediate frequency converter 40: Ghost elimination circuit

30: synchronous separation circuit 60: switching unit

80: Adder MC: Micom

41: analog-to-digital converter 42: ghost removal unit

43: memory 44: sync and field ID separator

45: window pulse generator 46: microprocessor

47: Roman 48: Digital / Analog Converter

The present invention relates to an on screen display (OSD) position control circuit in a ghost eliminator, and more particularly, an OSD character using a horizontal and vertical synchronous signal extracted from a ghost canceled signal. The present invention relates to an OSD position control circuit in a ghost eliminator which prevents position changes of OSD characters and stabilizes synchronization signals.

In order to eliminate the so-called ghost phenomenon caused by the reflection of radio waves from a mountain area or a building group, a broadcasting station transmits a constant reference signal so that the receiving side can know the characteristics of the transmission channel. The ghost is removed by filtering the filter by its reverse characteristic. In this case, the reference signal transmitted from the broadcasting station is referred to as a ghost canceling reference signal (hereinafter referred to as a GCR).

FIG. 1 is a block diagram of a conventional ghost canceller, which separates a tuner and an intermediate frequency converter 20, horizontal / vertical synchronization signals HD, VD, and field ID signals that process a signal received by an antenna ANT. A synchronous separation circuit 30 for detecting the synchronous detection signal HDet, a ghost removal circuit 40 for removing ghost signals, and a switching unit for selecting and outputting one of ghost removed signals and original signals not ghost removed ( 60), the microcomputer (MC) for outputting the OSD signal by the horizontal / vertical synchronous signal, the adder (80) to superimpose the video signal output from the switching unit 60 and the OSD signal output from the microcomputer (MC) )

The sync separation circuit 30 is connected to an output terminal of the tuner and the intermediate frequency converter 20, and detects the presence of a sync signal from an input video signal, and outputs the sync signal as a sync detection signal HDet. 31), one input terminal is connected to the output terminal of the tuner and the intermediate frequency converter 20, the other input terminal is grounded, and the control terminal is connected to the output terminal of the synchronization detector 31, the output of the synchronization detector 31 When the video signal and the ground signal is selected according to the switch 32 and the video signal input and connected to the output terminal of the switch 32, if there is a synchronous component in the input video signal in the horizontal / vertical synchronous signal ( HD and VD) are separated and output, and if there is no synchronous component, a synchronous separation section 33 generates and outputs a similar composite synchronous signal.

At this time, the sync detection signal HDet is a signal indicating whether or not there is a sync component in the input video signal, that is, a signal for determining whether or not a video signal is present.

FIG. 2 is a detailed block diagram of the ghost removing circuit 40. The output terminal of the analog / digital converter 41 converting the video signal output from the tuner and the intermediate frequency converter 20 of FIG. A ghost removing unit 42 for removing ghost is connected, and an output terminal of the ghost removing unit 42 is connected to one input terminal of a memory 43 that stores a video signal, and a microprocessor is connected to an output terminal of the memory 43. One input terminal of 46 is connected. In addition, a window pulse generator 45 is connected to one output terminal of the microprocessor 46. At this time, the memory 43 is composed of a FIFO (First IN First OUT) memory.

On the other hand, in the video signal output from the tuner and the intermediate frequency converter 20 of FIG. 1, a horizontal / vertical synchronization signal (HD, VD), field ID (signal distinguishing whether the input video signal is an odd field or an even field). ), Horizontal / vertical synchronous signals HD and VD and field ID signals outputted from the synchronous and field ID separator 44 are output to the synchronous and field ID separator 44 for outputting the synchronous detection signal HDed. And a window pulse generator 45 for outputting a window pulse corresponding to a line on which the GCR signal is loaded by line information output from the microprocessor 46.

The other end of the memory 43 is connected to an output terminal of the window pulse generator 45.

On the other hand, the other input terminal of the microprocessor 46 is connected to the output terminal of the GCR ROM 47 in which the reference GCR signal is stored, and the other output terminal of the microprocessor 46 is output from the analog-to-digital converter 41. The other input terminal of the ghost removing unit 42 for removing a ghost signal from the video signal is connected.

In addition, the memory 43 is connected to an output terminal of the ghost remover 42, and a digital / analog converter 48 for converting a signal from which ghost is removed from the ghost remover 42 to an analog signal is connected. .

At this time, the synchronization separation circuit 30 of FIG. 1 and the synchronization and field ID separation unit 44 of FIG. 2 are separately shown for simplicity of the same block or description. That is, the sync and field ID separator 44 corresponds to the sync separator 30 of FIG. The actual configuration of this synchronization-related part can be easily implemented by using a uPC1860 timing IC manufactured by NEC of Japan.

The conventional ghost eliminator configured as described above converts the signal received by the antenna ANT into a video signal of the baseband through tuning and VIF module processing by the tuner and the intermediate frequency converter 20 to switch with the ghost elimination circuit 40. It is output to the unit 60.

In addition, the video signal of the baseband is output to an input terminal of the synchronization detector 31 and the switch 32 of the synchronization separation circuit 30. The synchronization detector 31 detects the presence or absence of a synchronization signal in the input video signal and outputs a determination result to the control terminal of the switch 32.

The switch 32 selects a video signal input according to the synchronization detection signal HDet of the synchronization detection unit 31 provided to the control terminal or selects a ground signal and outputs the signal to the synchronization separation unit 33.

In this case, in order to express the OSD characters in the adapter-type video device, the horizontal / vertical synchronization signals HD and VD are separated from the input video signal, and output to the microcomputer MC to add the OSD signal based on this signal. In (80), an OSD character is displayed by outputting the video output signal to the screen.

In this case, when there is no input video signal and synchronization cannot be separated, a pseudo composite synchronization signal is generated to express the OSD.

Therefore, if the signal input through the switch 32 is a signal output from the tuner and the intermediate frequency converter 20, the synchronous separator 33 separates the actual horizontal / vertical synchronous signals HD and VD to the microcomputer. If the signal input through the switch 32 is a ground signal, a similar compound synchronization signal is generated and output to the microcomputer MC. The horizontal synchronizing signal HD and the vertical synchronizing signal VD serve as reference for position display of the OSD.

In this case, the sync detector 31 and the sync separator 33 are required to cut the signal input and obtain a similar sync signal when there is no video signal input as mentioned above. That is, in order to express the OSD at the time of no signal, signal cutting is performed by the synchronization detection signal HDet indicating whether there is synchronization in the input video signal and indicating the presence or absence of the synchronization.

The ghost elimination circuit 40 removes the ghost signal from the input video signal and outputs the ghost signal to the switching unit 60. The ghost removing circuit 40 outputs a selection signal c1 for selecting the original video signal i1 and the ghost removed signal i2 to the control terminal of the switching unit 60. At this time, the selection signal c1 is configured to be selected by the user.

The ghost elimination circuit 40 will be described in more detail with reference to FIG. 2.

The video signal of the baseband output from the tuner and the intermediate frequency converter 20 is output to the analog-to-digital converter 41 to be converted into a digital signal, and at the same time, to the sync and field ID separator 44 to be horizontal. Detect and detect vertical synchronization signals (HD, VD) and field ID signals.

The horizontal / vertical synchronization signals HD and VD and the field ID signal separated by the synchronization and field ID separation unit 44 are output to the window pulse generator 45, and the window pulse is transmitted by the microprocessor 46. When the line information is output to the generator 45, the window pulse generator 45 corresponds to a line on which the GCR signal is loaded by the horizontal / vertical synchronization signals HD and VD, the field ID signal, and the line information. A window pulse is generated and output to the FIFO memory 43.

On the other hand, in the initial state, the output of the analog-to-digital converter 41 is output to the ghost remover 42, and the ghost remover 42 outputs the original video signal from which the ghost signal is not removed. Print it out and save it.

The microprocessor 46 reads the GCR video signal from the FIFO memory 43 by the window pulse output from the window pulse generator 45 and outputs the GCR video signal from the GCR ROM 47. The characteristics of the channel are grasped in comparison with the reference GCR signal, and the reverse characteristic thereof is output as a control signal (filter coefficient) to the ghost removal unit 42.

Since the ghost removal unit 42 is usually a combination of a plurality of FIR filters and a plurality of IIR filters, the video signal output from the analog / digital converter 41 by the control signal output from the microprocessor 46. The ghost is removed from and output to the switching unit 60 of FIG. 1 through the digital-to-analog converter 48.

The microprocessor 46 outputs, to the control terminal of the switching unit 60, an original video signal i1 that is not ghost removed and a selection signal c1 for selecting the ghost removed signal i2. . In this case, the selection signal c1 may be configured to be selected by holding. In other words, the signal selected by the user and the selection signal of the microprocessor 46 may be ANDed.

The feedback of the output of the ghost removing unit 42 back to the FIFO memory 43 is obtained in order to obtain a channel characteristic, to verify whether or not ghost removal is properly performed, and to prepare for an initial signal processing or an abnormal occurrence. Is present, the microprocessor 46 controls the switching unit 60 to select the original signal i1 that is not ghost removed.

Meanwhile, the ghost removed signal i2 output from the ghost removal unit 40 and the original signal i1 not ghost removed are output to the switching unit 60. The switching unit 60 selects the ghost removed signal i2 and the original unghosted signal i1 by the selection signal c1 input to the control terminal, outputs the added signal to the adder 80, and adds the adder 80. ) Adds the OSD signal output from the microcomputer (MC) and outputs it on the screen to display the channel number or volume on the OSD.

However, the above circuit has a problem in that the position of the OSD character is changed as shown in FIG. 4 due to the delay present in the transversal filter of the ghost removal unit 42 as shown in FIG.

That is, a certain amount of delay is generated with respect to the input signal according to the number of taps of the filter configured in the equalization operation by the transversal filter, so that the horizontal signal separated based on the input video signal When the OSD operation is controlled using the vertical sync signal, the OSD position moves to the left when ghost is removed.

In addition, separating the horizontal / vertical synchronous signal from the ghost signal has a problem that the synchronous signal is unstable because the synchronous detection is always performed on the ghost signal even when the ghost is removed.

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and an object of the present invention is to provide a synchronization detector for detecting the presence of a synchronization signal in an input video signal, and a synchronization separator for separating a horizontal / vertical synchronization signal from a ghost removed signal. The present invention provides an OSD position control circuit in a ghost eliminator which obtains a fixed and stable synchronizing signal of the OSD position.

Another object of the present invention is to remove the horizontal / vertical synchronization signal from the ghost removed signal when the video signal is normally input, and to use it as a reference for position display of the OSD. An OSD position control circuit is provided.

Features of the OSD position control circuit in the ghost eliminator according to the present invention for achieving this object, a tuner and intermediate frequency converter for converting the signal received by the antenna to a video signal of the baseband, and the presence or absence of a synchronization signal A synchronous separation circuit for outputting an actual synchronous signal and a similar synchronous signal, a ghost cancellation circuit for removing a ghost signal from the video signal, and an original signal whose ghost is not removed by a selection signal output from the ghost removal circuit according to the present invention. And a switching unit for selectively outputting a signal from which ghosts are removed, a microcomputer for outputting an on-screen display signal locked to the horizontal / vertical synchronization signal output from the synchronous separation circuit, an output of the microcomputer and an output of the switching unit. In the ghost eliminator consisting of an adder, the tuner and the intermediate frequency converter Synchronization detection means for detecting the presence or absence of a synchronous signal at the output, and synchronous signal separation means for performing synchronous separation using the output of the switching unit when the synchronous signal is detected by the synchronous detection unit.

Hereinafter, a preferred embodiment of the OSD position control circuit in the ghost eliminator according to the present invention will be described in detail with reference to the accompanying drawings.

5 is a simple block diagram showing an OSD position control circuit in a ghost eliminator according to the present invention, a tuner and an intermediate frequency converter 20 for processing a signal received by an antenna ANT, and a horizontal / vertical synchronous signal (HD). , VD) and the field ID signal are separated, and the synchronization separation circuit 30 for detecting the synchronization detection signal (HDet) and the like, the ghost removal circuit 40 for removing the ghost signal, the ghost removed signal and the original ghost not removed A switching unit 60 for selecting and outputting one of the signals, a microcomputer (MC) for outputting the OSD signal by the horizontal / vertical synchronous signal, the video signal output from the switching unit 60 and the output from the microcomputer (MC) The adder 80 superimposes and outputs an OSD signal. At this time, the configuration and operation of the ghost removal circuit 40 is the same as the second diagram, and will be omitted.

At this time, the synchronous separation circuit 30, the synchronous detection unit 31 connected to the output terminal of the tuner and the intermediate frequency converter 20, one input terminal is connected to the output terminal of the switching unit 60 and the other input terminal is grounded The control terminal has a switch 32 to which the output terminal of the synchronization detector 31 is connected, and a synchronization separator that is connected to the output terminal of the switch 32 to separate and output a synchronization signal according to the output of the switch 32. It consists of 33.

In the present invention configured as described above, the signal received by the antenna ANT is converted into a video signal of the baseband by the tuner and the intermediate frequency converter 20 and output to the ghost elimination circuit 40 and the switching unit 60, respectively. At the same time, it is output to the synchronization detection unit 31 of the synchronization separation circuit 30.

At this time, the synchronization detector 31 determines whether there is a synchronization component in the video signal output from the tuner and the intermediate frequency converter 20, and controls the switch 32 as a synchronization detection signal HDet. Output to the stage.

If the switch 32 is a signal indicating that there is a synchronous component in the video signal to which the synchronous detection signal HDet input to the control terminal is input, the switch 32 selects an output of the switching unit 60 and outputs it to the synchronous separation unit 33. do. The synchronous separator 33 separates the horizontal / vertical synchronous signals HD and VD from the output of the switching unit 60 and outputs them to the microcomputer MC.

On the other hand, if the switch 32 is a signal indicating that there is no synchronization component in the video signal input to the synchronous detection signal (HDet) input to the control terminal, since the ground signal is selected and output to the synchronous separator 33, synchronous separation The unit 33 generates a similar composite synchronization signal such as an actual horizontal / vertical synchronization signal and outputs the same to the microcomputer MC.

The microcomputer MC outputs an OSD signal to the adder 80 using the input horizontal / vertical synchronization signal as a reference for displaying the OSD character position.

Meanwhile, the switching unit 60 selects one of the original signal i1 that is not ghost removed and the ghost removed signal i2 by selecting the selection signal c1 output from the ghost removal circuit 40. Output to the adder 80, the adder 80 adds the signal output from the microcomputer MC and the signal selected and output by the selection signal c1 from the switching unit 60 to display the OSD text on the screen. Is displayed.

As described above, according to the OSD position control circuit of the ghost eliminator according to the present invention, in the signal processing including the ghost, the presence or absence of a synchronous signal is detected from an input signal that is not ghost removed, and the horizontal / vertical signal is removed from the ghost removed signal. By separating the synchronization signal, the positional change of OSD characters before and after ghost removal is eliminated, and a stable synchronization signal is obtained.

Claims (1)

In an on-screen display position control circuit for displaying an input video signal and an on-screen display signal, a ghost signal is removed from the received input video signal, and a first selection signal indicating whether or not a predetermined ghost removal operation has been performed. Generated ghost elimination circuit; If the predetermined ghost removal operation is performed in response to the first selection signal, output a ghost removed video signal output from the ghost removal circuit, or if the predetermined ghost removal operation is not performed, leave the input video signal as it is. Output switching unit; Synchronization detection means for detecting the presence of a synchronization signal in the input video signal and generating a second selection signal indicating whether the synchronization signal is confirmed; A selection unit for selecting an output of the switching unit in response to the second selection signal, or selecting a predetermined reference potential signal if the synchronization signal is not detected; A reference for separating a real sync signal from an output of the switching unit according to the output of the selector or generating a pseudo sync signal from the predetermined reference potential signal to control the position of the sync signal to display the on-screen display signal Synchronous separation means for outputting as a signal; A microcomputer for outputting the on-screen display signal locked to the reference signal output from the sync separation circuit; And an adder for adding the output of the micom and the ghost-removed video signal to output the video signal and the on-screen display signal together.