JP2667709B2 - Ghost evaluation value display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a ghost evaluation value display device for visually displaying an evaluation value of a ghost wave combined with a desired wave.

[Prior art] As a countermeasure against reception failure due to ghost, which is one of the pillars of clear vision (EDTV), a ghost removal reference signal (GC
With the adoption of the ghost elimination system using R signals), broadcasting stations nationwide will begin television broadcasting this fall by superimposing the GCR signal on the vertical retrace interval of the video signal. The GCR signal is superimposed on the 1,3,6,8 fields as a sinX / X bar waveform shown in FIG.
Since the pedestal waveform shown in FIG. 3B is superimposed on the 4, 5, and 7 fields, the entire circuit makes one cycle in 8 fields.
Sent according to the field sequence. This GCR signal has a flat amplitude characteristic sinX / X up to 4.2MHz without phase distortion.
4.2MHz to include sinX / X bar waveform which time-integrated waveform
It has a flat frequency characteristic and a ghost-removable range of 45 μs, and it is said that it is possible to improve a ghost image of 3 ⁻ to evaluation 4 by subjective evaluation.

FIG. 10 shows a schematic configuration of a conventional television receiver 1 to which a ghost removing device is applied. The television signal sent to the tuner circuit 3 via the receiving antenna 2 is tuned to a desired station, and then sent to the video detection circuit 5 via the video intermediate frequency amplification circuit 4. A ghost removal device 6 shown in FIG. 11 is connected to the video detection circuit 5, and the video signal from which the ghost wave combined with the desired wave has been removed is supplied to a video / color demodulation output circuit 7
Is sent out to the CRT picture tube 8.

The ghost eliminator 6 includes an AD converter 10 at the first stage and a DA at the last stage.
A ghost removal circuit 12 and a normal ghost removal circuit 13 are connected in tandem between the converters 11, and GCR signals extracted from between the circuits 10 to 13 are centered line by line through buffer memories 14, 15, 16. In this configuration, coefficients obtained through arithmetic processing by the central processing unit 17 are set in the transversal filters in the proximity ghost removal circuit 12 and the normal ghost removal circuit 13. 18 and 19 are a clock generation circuit and a timing generation circuit, respectively.

The calculation by the central processing unit 17 is performed in buffer memories 14 to 16
It starts by first removing the noise component from the GCR signal captured from. Following this, the central processing unit 17
The distortion-free GCR signal generated within the GCR signal and the detected GCR signal are compared in waveform, and the characteristics of the transmission path that generates the ghost wave are specified with respect to delay time (τ), phase (φ), and (DU ratio). Then, the above-mentioned respective coefficients are determined based on the specified characteristics, and the proximity ghost is used for removing the normal ghost.

[Problem to be Solved by the Invention] The television receiver 1 incorporating the ghost removing device 6 exhibits excellent performance with a residual ghost of 35 dB. However, such ghost removing performance is generally objective. Since there is no way to confirm, the ghost removal performance can be confirmed only by comparing the viewing with other television receivers that do not have the ghost removal device 6, and the ghost removal device 6 relies on the reception There is a problem that the basics of the receiving technology such as ghost improvement by adjusting the installation of the antenna 2 are easily neglected.

Note that the extent of the reception failure due to the ghost is determined by the ghost basic evaluation ratio pseudo-PDUR (Perceived DURR) so that the subjectively recognized ghost level can be determined objectively.
Ratio) and the ratio of the desired wave to the ghost wave (DU
A portable PDUR measuring instrument for measuring the PDUR by the calculation based on the ratio), the high frequency phase difference (φ), the delay time (τ) and the number of ghosts (n) has also been prototyped. However, the PDUR, which is an evaluation quantity that quantitatively represents the quality of the ghost image,
Is the ratio between the power of the desired wave and the total power of the ghost wave corrected for the visual psychological effect caused by the difference in the phase difference φ and the delay time τ. Extract and reproduce the video carrier from the
A 90-degree carrier is made to perform two-axis synchronous detection, or two synchronous detection outputs from which the carrier component has been removed by a low-pass filter are alternately switched for each field, and converted to an 8-bit digital signal by time division. AD conversion, AD
Complex pre-processing such as averaging the two converted detection outputs to improve the SN ratio is required.
Not only designed for the use of GCR signals,
The subsequent mathematical processing also requires a complicated algorithm and the circuit scale is large, so it is useful as a measuring instrument, but has a problem that it is unsuitable for a general household television receiver or the like.

In Japanese Patent Application Laid-Open No. 63-121391, "ghost measurement method", a random signal is superimposed during a vertical retrace period of a television signal, and replaced with a known signal sequence based on address information. There is disclosed a ghost measuring device that performs ghost measurement by performing a correlation operation using a known signal sequence. However, this one
It is a major premise that a random signal sequence is superimposed on a television signal, and it is necessary to superimpose a known signal sequence instead of the random signal sequence in a specific horizontal period within a vertical retrace period of the television signal. Unlike a signal in which a ghost removal range is set with a specific intention and a transmission sequence is determined in advance, such as a GCR signal, a random signal sequence intended only for ghost measurement and a known signal sequence are used. The range of use is limited, and the received television signal is extracted from a signal obtained by synchronous detection with a pair of reproduction carriers orthogonal to each other, and the signal sequence of the specific horizontal period is extracted based on the address information, Once stored, this signal communication is correlated with a known signal sequence that is stored inside beforehand to measure ghosts, and therefore for ghost measurement. The signal processing and calculation process are very complicated and troublesome, and the cost burden is not inexpensive, regardless of the hardware configuration or software processing. It is necessary to obtain the amplitude ratio between the desired wave and the ghost wave as the ratio of the absolute value of the correlation output of the two, and it is possible to measure the ghost with high accuracy. Obviously, it is not a type of measuring instrument sold to ordinary households as a tool for easy adjustment, and was limited to very specialized uses.

[Means for Solving the Problem] The present invention has been made to solve the above-mentioned problem, and from a received television signal in which a ghost wave is combined with a desired wave,
Ghost elimination reference signal extraction means for extracting a ghost elimination reference signal superimposed on a vertical retrace period including a waveform obtained by time-integrating a flat amplitude characteristic up to a certain band, and extraction by the ghost elimination reference signal extraction means The time-differentiated reference signal for ghost removal is extracted, the main component with visual appeal is extracted from this time derivative, and the extracted time derivative is integrated for each delay time block divided and set in consideration of the display resolution A ghost evaluation unit that calculates a ghost level as a ratio of a desired wave to a ghost wave and outputs a ghost evaluation value; and a display unit that visually displays an output evaluation value of the ghost evaluation unit. Things.

[Operation] The present invention provides a ghost removal reference signal superimposed on a vertical retrace period including a waveform obtained by time-integrating a flat amplitude characteristic up to a certain band from a received television signal in which a ghost wave is synthesized with a desired wave. , The time-differentiated extracted ghost removal reference signal, the main component with visual appeal is extracted from this time derivative, and the extracted time derivative is divided and set in consideration of the display resolution. The ghost evaluation value obtained by calculating the ghost level as the ratio between the desired wave and the ghost wave is visualized by integrating each time block, so that the performance judgment of the ghost removal device can be made objective, and the diagnostic material can be used for installing the receiving antenna. I will provide a.

[Embodiment] FIGS. 1 to 8 show an embodiment of the present invention.
This will be described with reference to the drawings. FIGS. 1 and 2 are a schematic configuration diagram and a main circuit configuration diagram, respectively, showing an embodiment of a television receiver to which the ghost evaluation value display device of the present invention is applied.
FIG. 4 is a flowchart and a signal waveform diagram for explaining the arithmetic operation of the central processing unit shown in FIG. 2, respectively.
FIGS. 4 and 5 are diagrams showing respective filtering characteristics of a window filter and a low-pass filter constituting a visual characteristic filter.

The television receiver 21 shown in FIG. 1 has a ghost removing device 22 and a ghost evaluation value display device 23 integrated therein. That is, the buffer memories 14 to 16 in the ghost removing device 22 constitute ghost removing reference signal extracting means, and the central processing unit 17 constitutes ghost evaluating means for outputting a ghost evaluation value quantified according to the set evaluation criteria. The on-screen display circuit 24, the video / color demodulation output circuit 7, and the CRT picture tube 8 constitute display means.
In the case of the embodiment, the ghost evaluation value is displayed two-dimensionally by displaying the delay time τ of the ghost wave on the horizontal axis and the level DU ratio on the vertical axis. This method divides into delay time blocks at regular intervals (for example, about 10 μs) and performs a comprehensive evaluation for each block. In other words, the ghost level calculated for each delay time block is divided into about four steps from 40 dB to 0 dB and displayed as a light emitting area according to each level.

The calculation in the central processing unit 17 is performed by using the GC captured from the received television signal through the buffer memories 14 to 16.
As shown in step (101) of FIG.
Differentiate over time. As described above, the GCR signal transmits a sinX / X bar waveform obtained by time-integrating a flat amplitude characteristic sinX / X waveform up to 4.2 MHz without phase distortion and a pedestal waveform in accordance with an eight-field sequence. By time-differentiating, waveform distortion generated in the transmission path can be extracted. Next, in step (102), the differentiated waveform is passed through a visual characteristic filter to extract features that match human visual characteristics. In the embodiment, considering that a ghost adjacent with a very short delay has no visual appeal, a window filter having a dip centered at zero delay as shown in FIG. 5 is used. Excludes super close ghosts. In addition, a direct ghost mainly composed of high-frequency components due to the time differentiation process described above does not involve a change in the DC level, so that the visual appeal is weak, and the low-pass filter having the band characteristic shown in FIG. By removing it, the level of direct ghosts is suppressed. The GCR signal that has passed through the visual characteristic filter is subjected to the above-described delay time block division processing in the subsequent step (103), and as shown in FIG. 4B, the delay time block T ₁ having a fixed period as a unit. , T ₂ , .. The differentiated waveform of the ghost wave divided into the delay time blocks is subjected to DU ratio evaluation shown in the following step (104) after unifying the polarity into positive polarity pulses as shown in FIG. 4 (C). . The DU ratio is to be compared with the time differential value of the distortion-free ghost removing reference signal generated in the central processing unit 17 and the time differential value of the ghost wave accumulated in each divided delay time block Tn. Is calculated. Then, here, the calculated DU ratio is used as a ghost level for each delay time block in step (105) from the central processing unit 17 to the on-screen display circuit 24 and the video / color demodulation output circuit 7.
Is output to the CRT picture tube 8.

Therefore, the on-screen display circuit 24 inserts and displays the ghost evaluation graph with the delay time block on the horizontal axis and the ghost level on the vertical axis on the screen of the television receiver 21. Therefore, by referring to the ghost evaluation graph in which a part of the main screen is inserted and displayed, the degree of the ghost failure can be known, and the direction of the receiving antenna 2 is adjusted according to the delay time and the ghost level. It is possible to remove ghosts in a state where ghost obstacles are least.

In this way, the ghost evaluation value display device 23
Rather than measuring the ghost level by a rigorous calculation like a measuring instrument, using the GCR signal sent by being superimposed on the television signal, the degree of ghost failure is taken as the relationship between delay time and ghost level, It can be visually displayed in the most easy-to-understand form, and in ghost evaluation, super close-up ghosts with weak visual appeal are excluded from the evaluation target, and orthogonal ghosts without DC level change are evaluated. Since the level is suppressed, it is possible to give an objective judgment standard by subjectively grasping the ghost disorder. Furthermore, unlike a conventional PDUR measuring device that evaluates a plurality of ghosts by replacing them with a single ghost, the time distribution of the ghosts is displayed. The degree of ghost failure that differs for each reception channel due to the geographical relationship can be displayed together with the image being selected and received, so that the ghost evaluation value can be displayed in a form that is easier to store.

In the above embodiment, the television receiver 21 having the on-screen display function is used as the display means of the ghost evaluation value. However, the television receiver 31 shown in FIG.
As described above, a ghost meter 33 for displaying a ghost level can be incorporated in the ghost removing device 32. As the ghost meter 33, an LCD display using a liquid crystal, an LED display using a light emitting diode,
Alternatively, a VFD display using a fluorescent tube or the like can be used.

In addition, as shown in FIG.
The ghost eliminator 42 of the type used by connecting to the ghost eliminator 42 can transmit an on-screen signal, but the ghost eliminator 42 itself has a dedicated ghost meter 43 for displaying a ghost evaluation value. It is good to provide.

[Effects of the Invention] As described above, the present invention provides a vertical flyback period including a waveform obtained by time-integrating a flat amplitude characteristic up to a certain band from a received television signal obtained by combining a ghost wave with a desired wave. Extract the superimposed ghost elimination reference signal, time-differentiate the extracted ghost elimination reference signal, extract the main component with visual appeal from this time differential value, and display the extracted time differential value. , The ghost evaluation value obtained by calculating the ghost level as the ratio of the desired wave and the ghost wave is visually displayed. Rather than measuring the ghost level by simple calculation, the ghost elimination reference signal sent superimposed on the television signal has time-integrated flat amplitude characteristics up to a certain band. Utilizing the fact that the distortion characteristic of the transmission line can be obtained as it is by integrating the received ghost removal reference signal with time, the degree of ghost is calculated by the minimum necessary calculation, and the delay is reduced to the degree of ghost failure. The relationship between time and level can be visually displayed in the most understandable form.Moreover, instead of a ghost level measuring device, the level is displayed for the ghost removed by the ghost removing device. The operating state can be grasped at a glance, which makes it possible to recognize the performance of the ghost eliminator and to rely on the performance of the ghost eliminator. Provide reliable judgment for optimal reception in the reception area And an excellent effect such that anyone can easily and optimally receive.

Further, the present invention provides a ghost evaluation procedure in which a ghost removal reference signal which is distorted by a ghost wave is differentiated with respect to time, and a visual characteristic filter means which extracts a main component having visual appeal from a differential output of the differentiating means. And a block dividing unit that divides the differential output obtained by the visual characteristic filter unit into delay time blocks set in consideration of display resolution, and the differential output is divided for each of the blocks divided by the block dividing unit. By integrating and calculating the ghost level as a ratio between the desired wave and the ghost wave, the ghost level is not measured by a strict calculation such as a PDUR measuring device. The degree of ghost is determined by the minimum necessary calculation from The ghost removal device can be visually displayed in the most easy-to-understand form, and can be easily incorporated into the ghost removing device without imposing a significant cost burden.

As the visual characteristic filter means, a window filter that narrows the passing level in a certain period before and after the delay time zero and a low-pass filter that blocks the passage of high-frequency components generated in the preceding time differentiation process are used. , Super-close ghosts with weak visual appeal and orthogonal ghosts mainly composed of high-frequency components are suppressed from each other and excluded from evaluation targets, and a more objective judgment criterion is used for the evaluation of ghost disorders that are subjectively grasped. And the like.

Also, by using a display that displays the two-dimensional visual display with the delay time on the horizontal axis and the vertical axis on the ghost level as the display means, unlike a conventional PDUR measuring device that replaces and evaluates a plurality of ghosts with a single ghost. It is possible to easily and clearly display the time distribution of the ghost that the user wants to know most.

Furthermore, the display means is constituted by a display terminal of the television receiver and a multiplex display circuit for multiplexly displaying the ghost evaluation value on the screen of the display terminal, so that both the ghost removing device and the ghost evaluation value display device are provided on the television. The ghost evaluation value can be clearly displayed on the display screen of a television receiver with an on-screen function by incorporating it in a television receiver. Since the degree of the obstacle is displayed together with the image being tuned in,
The ghost evaluation value can be displayed in a more convincing manner.

Further, by using a display terminal using a liquid crystal as a display element, a display terminal using a light-emitting diode as a display element, or a display terminal using a fluorescent tube as a display element, as the display means,
A dedicated display device can be provided in a place other than the screen frame of the television receiver, and a ghost removal device of a type used by connecting to the television receiver is used to display a ghost evaluation value on the ghost removal device itself. And a display device dedicated to the intended use can be assembled.

[Brief description of the drawings]

1 and 2 are a schematic configuration diagram and an essential circuit configuration diagram showing an embodiment of a television receiver to which the ghost evaluation value display device of the present invention is applied, and FIGS. 3 and 4 are respectively FIG. 5 and 6 are flowcharts and signal waveform diagrams for explaining the arithmetic operation of the central processing unit shown in FIGS. 5 and 6, respectively, are diagrams showing respective filtering characteristics of a window filter and a low-pass filter constituting a visual characteristic filter. FIGS. 7 and 8 are schematic configuration diagrams each showing another application example of the ghost evaluation value display device of the present invention, and FIGS. 9A and 9B are waveform diagrams each showing an example of a ghost removal reference signal. 10 and 11 are a schematic configuration diagram and a circuit configuration diagram of an essential part showing an example of a conventional television receiver to which a ghost removing device is applied, respectively. 7 Video / color demodulation output circuit 8 CRT picture tube 14,15,16 Buffer memory 17 Central processing unit 21,31,41 Television receiver 22,32,42 Ghost removal Device 23… Ghost evaluation value display device 24… On screen display circuit 33,43… Ghost meter

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Tatsuya 3-5-24 Miyahara, Yodogawa-ku, Osaka-shi, Osaka Examiner, NEC Home Electronics Co., Ltd. Mitsutake Fujiuchi (56) References JP-A-63-121391 JP, A)

Claims (8)

(57) [Claims] 1. A ghost removal reference signal superimposed in a vertical retrace period including a waveform obtained by time-integrating a flat amplitude characteristic up to a certain band is extracted from a received television signal in which a ghost wave is combined with a desired wave. Ghost removal reference signal extraction means, and a ghost removal reference signal extracted by the ghost removal reference signal extraction means are time-differentiated, and the time derivative is used to extract and extract a main component having visual appeal. Ghost evaluation means for accumulating the time derivative values for each of the delay time blocks divided in consideration of the display resolution, calculating a ghost level as a ratio between a desired wave and a ghost wave, and outputting a ghost evaluation value; A ghost evaluation value display device comprising: a display means for visually displaying an output evaluation value of the means. 2. The ghost estimating means includes a differentiating means for time-differentiating a ghost removing reference signal distorted by a ghost wave, and a visual characteristic filter means for extracting a main component having a visual appeal from a differential output of the differentiating means. And a block dividing unit that divides the differential output obtained by the visual characteristic filter unit into delay time blocks set in consideration of display resolution, and the differential output is divided for each of the blocks divided by the block dividing unit. 2. The ghost evaluation value display device according to claim 1, further comprising integrating means for integrating and calculating a ghost level as a ratio between a desired wave and a ghost wave. 3. The visual characteristic filter means includes a window filter for narrowing a passing level in a predetermined period before and after a delay time of zero, and a low-pass filter for blocking passage of a high-frequency component generated in a time differentiation process in a preceding stage. The ghost evaluation value display device according to claim 2, further comprising a filter. 4. The ghost evaluation value display device according to claim 1, wherein said display means is a display for two-dimensionally displaying a delay time on a horizontal axis and a vertical axis on a ghost level. 5. The ghost evaluation according to claim 1, wherein said display means includes a display terminal of the television receiver and an on-screen display circuit for multiplexing display of a ghost evaluation value on a screen of the display terminal. Value display device. 6. The ghost evaluation value display device according to claim 1, wherein said display means has a display terminal using a liquid crystal as a display element. 7. The ghost evaluation value display device according to claim 1, wherein said display means has a display terminal having a light emitting diode as a display element. 8. The ghost evaluation value display device according to claim 1, wherein said display means has a display terminal having a fluorescent tube as a display element.