JPS62289092A - Regeneration method for color television signal and color television receiver - Google Patents

Abstract

PURPOSE:To regenerate a high resolution and high definition image by frequency-converting a high frequency luminance signal included in a color television signal, transmitting said signal within a standard transmission band and regenerating it. CONSTITUTION:The high frequency component YH at 4.2-6.2 mHz included in the luminance signal is frequency-shifted and moved to at 2.2 mHz-4.2 mHz. On a receiver side, a band-pass filter 11 extracts components lying at 2.2-4.2 mHz, which pass through a 262 H delay element 12 and a 1H delay element 13. A difference circuit 14 extracts the component YH included in the luminance signal, and takes out a component C comprising a chrominance component C from a difference circuit 15. A synchronizing detection circuit 17 demodulates the chrominance component C, takes out two color difference components, that is, signals I and Q. A frequency shift circuit 18 frequency-shifts the component YH of the luminance signal to 4.2-6.2 mHz, and an adder circuit 9 adds said component to the luminance signal.

Description

Detailed Description of the Invention [Field of Application in Industry-1-1] The present invention relates to a method and apparatus for reproducing a color television signal, and more specifically, a method and apparatus for reproducing a color television signal. A composite color television signal in which a carrier color signal is frequency-multiplexed is further converted into a composite color television signal in which another information signal, such as a high-frequency luminance signal, is frequency-converted and multiplexed. The present invention relates to a method for separating and reproducing signals, and an apparatus therefor.

[Conventional technology]

The video signal band of conventional television signals is limited by the standard, and there is a limit to the improvement in resolution. In addition, if you really want to increase the resolution, remove the band limit of the standard and use 4, 2
For example, it was necessary to take measures such as transmitting at 6.0 MHz instead of MH.

[Problem that the invention seeks to solve]

-4= It was difficult to improve the resolution of conventional television signals within the standard transmission band.

Therefore, the present invention transmits a color television signal having a luminance signal having a wider band than the transmission band within a predetermined transmission band such as a standard, and reproduces the luminance signal having a wider band on the receiving side, The object of the present invention is to realize a color television signal reproduction method that reproduces high-resolution, high-definition images, and a receiver for the same.

[Means for solving problems]

The present invention divides the brightness signal of a color television signal into a high-band brightness signal higher than a certain horizontal frequency and a low-band brightness signal lower than a certain horizontal frequency. A color television that multiplexes and transmits (including records) a low-range luminance signal, a modulated chrominance signal, and the frequency-converted modulated luminance signal as a signal that has a conjugate relationship with the frequency domain of a carrier color signal in the frequency domain. In order to separate the low brightness signal 1 fish signal and the high band brightness signal from the John signal, the subcarrier of the modulated color signal and the subcarrier of the modulated brightness signal have a certain phase relationship,
-I- By utilizing the phase relationship of the originating carrier wave, -1) the low-band luminance signal, high-band luminance signal ON, and color signal are separated and reproduced.

〔Example〕

First, in order to facilitate understanding of the present invention, an NTSC color television signal and a color television signal that is an input signal of the color television receiver of the present invention will be explained.

FIG. 1 schematically shows the relationship between fields and scanning lines of an NTSC TV signal.

When this is viewed from the left (y-direction perpendicular to the plane), the relationship between fields and scanning lines is as shown in FIG. In the figure,
Circles represent scanning lines.

In the NTSC system, as is well known, color (i number (color difference signal)
is constructed by modulating it with a color subcarrier. In Fig. 2, (P, ψ + π) indicates the phase relationship of this color subcarrier.
Fig. 3 shows the frequency ν in the vertical y direction (referred to as the temporal frequency) and the frequency ν in the vertical y direction (referred to as the vertical frequency). Note that since it is point symmetrical about the origin, it is sufficient to indicate two chapter limits.

- First, the frequency fI3 indicates a spatio-temporal frequency based on interlaced scanning, as is well known. Also, the frequency f8C is NTS
This is a spatio-temporal frequency corresponding to the color carrier frequency of the C signal.

In addition, the luminance signal is the origin of the frequency, fB + fB'r f
,'' and f, 3/# exist as sideband waves. These luminance signals, the baseband signals of the sidebands, and the sideband signals overlap each other and may result in image quality problems.
It is desirable to limit the bandwidth in advance. However, since some techniques for this are already known, their explanation will be omitted.

In the above explanation, the band in which the vertical two-time frequency components are vacant is indicated as fY+fY' in the figure. That is, the time-frequency axis f and the vertical frequency axis ν are orthogonal to the spatio-temporal frequency domain expressed in two dimensions of the time frequency f and the vertical frequency ν.
When divided into four quadrants, the carrier color signal is divided into the second and fourth quadrants.
It is distributed near the subcarrier f8c+fBc' in the quadrant, and the first
Quadrant = 7- Therefore, in the vertical and temporal frequency domain of the existing color TV signal, other information of the color signal and the luminance signal of the existing color TV signal, such as the horizontal height of the luminance signal that could not be transmitted in the past. The above-mentioned first quadrant is obtained by converting the frequency of the domain signal component,
A new color TV signal is constructed by inserting it into a region near the frequency fN'+fY' in the third quadrant, that is, a frequency region conjugate with the frequency region of the carrier color signal, and frequency multiplexing it.

FIG. 4 is a horizontal frequency distribution diagram for explaining the frequency conversion of the high-frequency component Y of the two series of luminance signals.

In a color TV signal based on the NTSC system, the luminance signal is 0.
~4.2 MHz. Therefore, in order to transmit fine image information, the high-frequency components ■ and □ of the luminance signal of 4.2 to 6, 2 MH7, are frequency shifted, for example, 2 MHz.
, 2 MHz to 4, 2 MHz. The TV signal frequency-multiplexed in this way is 4.2 MHz.
.

The receiver reproduces the high-frequency components Y and I of the luminance signal by performing a series of reverse operations.

FIG. 5 shows an embodiment of the overall configuration of a color television signal communication system including a color TV receiver according to the present invention.

In the figure, A, B, and C are color television signal transmitting units and transmission media (transmission in a broad sense including recording), respectively.
and the receiving section. In order to simplify the explanation, only the video signal section directly related to the present invention will be shown, and since the audio signal, synchronization signal, etc. are the same as in the existing TV system, the explanation will be omitted.

The transmitter Δ adds the luminance signal Y9 and the color difference I, Q to a so-called well-known color encoder 1 to obtain a nearly standard NTSC signal, and also adds this high-frequency luminance signal Y, □ to a high-frequency wave generator 2. obtain. Then, the frequency is shifted by a frequency shift circuit 3. This circuit will be described later. At this time, as can be seen from FIG. 3, it is preferable to band-limit the frequency bandwidth of the high-frequency luminance signal Y□ in the vertical 9-time direction by a known method because this reduces crosstalk.

An adder 4 adds the 11♂ power of the color encoder 1 and the output of the frequency shift circuit 3 to generate an expanded NTSC signal. This expanded NTSC signal is modulated in a form suitable for transmission by a transmitter 5. .

The transmission section B is usually a space for transmitting radio waves, but is not limited to a space and may be a recording medium or the like.

The receiving section C is a color television receiver according to the present invention, and performs operations opposite to those of the transmitting section, and will be described later.

In the embodiment shown in FIG. 5, since the luminance signal Y has a higher luminance component than the conventional one, a reproduced image with higher resolution can be obtained. Furthermore, by combining this with a conventionally proposed scanning line interpolation technique, a reproduced image of even higher quality can be obtained.

Next, an embodiment of the processing of the high frequency luminance signal YH of the color television signal applied to the receiver of the present invention will be described. As mentioned above, the high frequency luminance signal Y1□ is frequency converted (shifted) and transmitted to an empty area in the spatio-temporal frequency domain, and as an example, as shown in FIG. The color signals are sent in the second and fourth quadrants, and the high-range luminance signals ■ and □ are sent in the first and third quadrants. That is, the former color signal is sent using a subcarrier with a phase as shown in FIG. 2, and the latter high-range luminance signal is sent using a subcarrier with a phase as shown in FIG.

More specifically, according to the standard, the color signal is a subcarrier that has a phase relationship as shown in Figure 2, that is, the phase is inverted for each scanning line (line period) and has the same phase as the carrier wave of the current scanning line. The scanning line of the previous field is below the above-mentioned current scanning line (262 H before in the case of NTSC system in terms of the number of scanning lines)
It is modulated with a subcarrier wave that becomes a scanning line. On the other hand, the high-frequency luminance signal in the present invention has a subcarrier having a phase relationship as shown in FIG. The scanning line is above the current scanning line (NTSC
In the case of the method, it is modulated with a subcarrier that becomes a scanning line (263H before).

First, an example of frequency shifting in the transmitting section will be described. As is well known, a signal of frequency f, has a frequency f. By multiplying the signals, a signal with frequency f, ±fo is obtained. For example, a signal with a frequency f1-fo can be obtained by using a bandpass filter. Therefore, as one method, as shown in Fig. 8, f o"f g c/2 = 3.58/21: MHz'3
”=], 8MHz signal, wideband 4.0~6.Q
Multiplying the MHz signal gives 2.2 to 4,2 M
The frequency can be shifted to H7. In addition, fj
When <fo, the vertical relationship of the shifted frequencies is reversed.

Frequency f. One method for obtaining a signal (subcarrier) is, for example, a color subcarrier fg. There is a method of adopting frequencies related to . For example, this may be divided into 1/2. However, it is necessary to ensure that the phase has the above-mentioned relationship for each scanning line and to match the transmission and reception. Also, although an offset occurs in the phase at the end of the scanning line, it is natural to reset it at the beginning of the scanning line so that the conditions shown in FIG. 6 are satisfied. Now, the color subcarrier f
As is well known, SC is matched for sending and receiving. In the case of frequency division, four uncertainties may occur as shown in FIG. That is, there are four possible fs c /2 values for the frequency fBc shown by the solid line, as shown by the dotted lines. Which of these is the case can be easily identified in the receiving section by directly inserting the fsc/'2 signal in a burst manner for a certain period of time into a part of the signal, such as a vertical synchronization part. Also, without this signal, normal NTSC
It can also be identified as a signal.

Specifically, for example, internal signal processing is performed using the color subcarrier fs.
If the clock signal is four times c, that is, the frequency is 4f8G, pulses as illustrated in FIG. 9 will be generated, but only an instruction is given as to which phase of the pulse is to be adopted. Therefore, in addition to the method of directly inserting the f g c /2 signal as described above, there are various methods such as inserting a digital code.

Next, an embodiment of a method for separating the color signal component and the high-range luminance signal component YH from the signal component in the receiving method of the present invention will be described.

Figure 7 shows the receiving circuit (part C in Figure 5) for this purpose.
This is an example. To do this, first the frame memory 16
extracts components that change from frame to frame. This includes a high frequency luminance signal Y,1 and a color signal C. This is passed through a 2.2 to 4,2 M I (z component) by a band pass filter 11. This is passed through a 262 H delay element 12 and an IH delay element 13 (here 1-1 is the horizontal scanning line period). Delay the signal.

This is led to the difference circuit] 4.15 as shown.

The difference circuit 14 calculates the difference between the signal and the signal delayed by 262H. On the other hand, as can be seen from FIGS. 2 and 6, the two color signals C having a 262H difference are in phase, and the luminance signal component Y11 is in reverse phase, so only the Y1□ component can be extracted. Similarly, only the color signal component C can be taken out from the difference circuit 15 which obtains the difference between two signals having a difference of 263H. As for the color signal, it is demodulated by the synchronous detection circuit 17 as usual.
It is sufficient to extract the two color difference signal components I signal and Q signal. Also, the luminance signal component■. As for
(In the first embodiment, the frequency is shifted to 4.0 to 6.0 MHz) and added to the luminance signal in the adder circuit 19.

That is, the frequency f is determined by the method described above. The signal of (fi
By obtaining the component of fo)+fo, it is possible to obtain the component of the shifted frequency f.

What is considered to be a problem in the present invention is image quality disturbance due to high-frequency luminance signal components, and this can be considered as follows.

(i) Interference can be avoided by subtracting the component obtained as described above from the original component.

(j, i) If no deduction is made in an existing receiver, etc., the interference is considered to be on the same level as the interference in a monochrome TV receiver caused by superimposing a color signal. That is, it is inverted for each frame, and the visual impact is considered to be small.

Many variations of the method shown in the embodiments are possible in the present invention. Listed below.

=15- (i) In the embodiment of the present invention, the NTSC signal system was explained, but in the case of the PAL system, it is as shown in FIG.
D retiery) “The Filtering of
Luminance and Chrominance Signals to Apoid Cross Force in a Pneel
Color system
1+uninance and Chromjnan
ce signals L.

avoid cross-color in s
F A T, coToor.

system) BC Engineering RB
CEngineerjng (sept, ) 976
)) Similarly, it is possible to insert two high-frequency signals (such as a high-frequency luminance signal) into a three-dimensional (ie, time-frequency domain, vertical frequency domain, and horizontal frequency domain) gap.

Furthermore, taking advantage of the fact that there are generally two gaps,
For example, in the case of PAr, method Y3. 5.5 to 8 M
It is also possible to insert 8 to 10.5MH7 into HZ and 'Y11'.

(11) As a method for eliminating imperfections in interlace scanning and obtaining high resolution in the vertical direction, for example, doubling the number of scanning lines in the receiving section and converting interlace to sequential scanning, as well as an appropriate method. How to increase the number of scanning lines by inserting
Of course, it is also free to adopt one method in combination with other methods. In addition, the original image signal is obtained by sequential scanning on the image sending side, and filtered with appropriate time and vertical frequency and 2i1
Techniques such as cutting out the Inter 1 North scanning signal (for example, Kay Lucas, ``Standards for Broadcasting Satellite 0 Service'')
adcast, ingS a t, e ] 1. j
IRA Tech
nical Review).

No, T8. It is also the designer's freedom to combine it with the original design (March 1982).

(iii) The circuit shown in FIG. 7 for separating the high-frequency luminance signal and the color signal is merely an example. It is also possible to further pass the output of this circuit to the next circuit if necessary. That is, by taking advantage of the fact that the phases are reversed between frames, it is possible to pass the frame through a filter that acknowledges the difference between frames, or to pass a certain v) pi same file 1! In this case, the sum of η is reversed between the scanning lines of .

Passing the signal through a filter that obtains the difference between scanning lines also helps improve characteristics.

(1v) As described above, for color difference signals and high-range luminance estimation, it is preferable to band-limit the vertical frequency and the temporal frequency in advance. There are known methods for limiting the vertical frequency, such as summing the outputs using horizontal periodic delay lines. The same thing can be done in the time direction as well, just by replacing it with a frame delay element.

In addition, regarding the luminance signal, color signals etc. are superimposed 2,
For 2-4, 2 MHz, f = 1587
．． , it is desirable to remove components near the band corresponding to the Yani 131 scanning line. , -Mochi4ki(v) In the frequency band where the color signal and the high-range luminance signal are superimposed, it is desirable to remove the baseband luminance signal component in advance.

(V'') The structure of the filter for extracting color signals and high-frequency luminance signals is shown in Figure 7 and two. However, it is possible that the method of the customer is not limited to L-anus. The circuit configuration and the expression by the transfer function are shown below (for purpose, the configuration shown in FIG. 7 is included. Here, only the circuit configuration and transfer function are described.

・(1-Z-"')(BPF) ・(IZ-282j")(RPF)(-1+27-'
-Z-2L)/4・(1z-262H) (RPF)
(+7-5251-1)...(in the case of Figure 7) ・(+-7-263)(BPF)(+-Z-52"')
Or a combination of these.

In the case of color signals, a similar configuration can be achieved by replacing 262H and 263TI.

Note that the gain may be determined as appropriate, including the function of the enhancer.

(vij) As is well known from the configuration of digital filters, the characteristics of the filter for sum or difference between fields can be further improved by, for example, the following configuration. That is, I Z -283) instead of 1] +2 z
26 B +-1-7-525H.

Furthermore, when a signal passes through two or more routes, it is common practice to make the delay times as uniform as possible using ordinary techniques.

〔Effect of the invention〕

According to the present invention, a high-resolution image is obtained from a television signal in which high-resolution information is inserted into a three-dimensional frequency gap and transmitted within the range of current television signal standards. effective.

That is, within the signal band of 4 and 2 MHz, 6 M
By inserting the Hz high-band luminance signal, it becomes possible to reproduce high-definition television signals without changing the current transmission equipment.

In addition, on the transmitting side as well as on the receiving side, or on the receiving side, there is a technique of doubling the scanning lines or scanning them sequentially (so-called improve TBI).
By combining with dTV) etc., horizontal direction,
By increasing the resolution in the vertical direction, it is possible to display high definition television images while maintaining compatibility.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the general concept of a TV signal, FIG. 2 is a general explanatory diagram showing the phase of a color subcarrier in the time-vertical domain, and FIG. An explanatory diagram showing the arrangement of high-band luminance signal components added to a television receiver, FIG. 4 is a diagram showing a frequency shift in the high-band luminance signal, and FIG. 5 is a TV signal transmission system including the receiving section of the present invention. FIG. 6 is an explanatory diagram showing the phase relationship of high-frequency signals in a color TV signal. FIG. 7 is a block diagram showing an embodiment of the present invention. FIG. A block diagram showing the embodiment, FIG. 8 is a diagram showing the frequency relationship to frequency shift 1 in one embodiment,
FIG. 9 shows the subcarrier ffJc and the frequency f for frequency shift. Fig. 10 is an explanatory diagram showing the relationship with the PAT signal.
, is a frequency allocation diagram when applied to . DESCRIPTION OF SYMBOLS 1... Color encoder, 3... Frequency shift 1~circuit, 12... Field (262H) delay element. , -゛, view\ ('tsu agent patent attorney Katsuma Ogawa, 4-55 1st area 2nd item 3rd item 4th item s g J:, grurx thtitnx kudzu S
Eye 2nd 7th/f)2

Claims (1)

[Claims] 1. Modulated color signals and modulation modulated by first and second subcarriers in mutually conjugate regions in a two-dimensional frequency domain of vertical and temporal frequencies with respect to the first luminance signal. a first step of inputting a composite color television signal multiplexed with a luminance signal; and a second step of separating the first luminance signal, the modulated luminance signal, and the modulated chrominance signal from the composite color television signal. a third step of demodulating a color signal from the modulated color signal separated in the second step; and a second step of demodulating a color signal from the modulated luminance signal separated in the second step.
A fourth step of demodulating the luminance signal of a fifth step of obtaining a color television signal. 2. In the description of item 1, the separation of the modulated color signal and the modulated luminance signal in the second step is performed such that one of the carrier waves of the modulated color signal and the modulated luminance signal has the same phase;
A method for reproducing color television signals by obtaining sum and difference signals between scanning lines separated by approximately one field, the other having an opposite phase. 3. A composite color television signal source including a signal in which the first luminance signal is multiplexed with a modulated luminance signal and a modulated chrominance signal that are in a mutually conjugate frequency domain in a two-dimensional frequency domain of vertical and temporal frequencies; , a separation circuit that separates the first luminance signal from the composite color television signal source, the modulated luminance signal and the modulated chrominance signal, and a second luminance signal from the modulated luminance signal obtained by the separation circuit. a first demodulating means for demodulating a color signal from the modulated color signal obtained by the separation circuit; a first demodulation means for demodulating a color signal from the modulated color signal obtained by the separation circuit; and a first demodulation means for demodulating the first luminance signal obtained by the separation circuit. A color television receiver comprising means for synthesizing the second luminance signals obtained in the above to obtain a third luminance signal. 4. In the color television receiver described in paragraph 3,
Color television reception characterized in that the first and second luminance signals are a low frequency luminance signal with a frequency lower than the one constant frequency and a high frequency luminance signal with a frequency higher than the one constant frequency, respectively. Machine. 5. In the color television receiver described in paragraph 3,
The phases of the first and second subcarriers are reversed every line period and frame period, and the first and second subcarriers in the current scanning line are inverted in phase.
and the phase of one subcarrier of the second subcarrier is approximately one field behind the current scanning line and equal to the phase of the one subcarrier of a scanning line located directly above the current scanning line,
A color characterized in that the phases of the first and second other subcarriers are approximately one field behind the current scanning line and equal to the phase of the other subcarrier of a scanning line located directly below the current scanning line. television receiver. 6. In the color television receiver described in paragraph 3,
The separation circuit cascades a bandpass filter that passes the modulated luminance signal and modulated chrominance signal from the composite color television signal, and a spatiotemporal filter that separates the modulated luminance signal and modulated chrominance signal from the output of the bandpass filter. A color television receiver comprising a connected circuit. 7. In the color television receiver described in paragraph 3,
The first luminance signal is equal to the luminance signal of the NTSC color television signal, and the modulated color signal is equal to the luminance signal of the NTSC color television signal.
Equal to the carrier color signal of a C color television signal,
A circuit for separating the modulated luminance signal of the separation circuit includes two
1. A color television receiver comprising a circuit for obtaining a difference between an input and an output of a delay means of 62H (H is a line period).