FIELD OF THE INVENTION The present invention relates to a method for modula¬ tion and demodulation of multiplexed color picture signal capable of 2-line scanning in order to in crease vertical resolution in color TV which is applicable in conventional scanning system, and a means for display thereof using 2- line electron beam.

BACKGROUND OF THE INVENTION

In the conventional raster scanning, it has been used only one line of electron beam in CRT, which may be now called one-line scanning. In order to achieve a high resolution TV image in this system, we may consider that the horizontal resolution can be increased by broadening bandwidth of video signal, and the vertical resolution may be enhanced by increasing number of lines in the scanning raster. However, this requires far extended transmission bandwidth and different television standard in comparison to NTSC television system.

An attempt to obtain a high resolution TV image has been disclosed in my prior Korean Patent Application No. 11342/89 entitled "Method for modulating Y/C signal", in which chrominance signal is separated from the luminance signal, and occurring of cross interference caused by the Y and C signal frequency components are interleaved in the

same baseband channel is originally prevented.

In this disclosure, the chrominance signal is modulat¬ ed in the same bandwidth as the chrominance signal of the conventional, NTSC system, in that the chrominance signal (fc*) has relationship of N x f _H (N=570) , with the lumi¬ nance signal which has bandwidth of 0-7. MHz, in order to simplify conversion to the modulated signal which is compatible with chrominance signal in the NTSC system.

While, luminance signal has bandwidth of 0-7.2 MHz and relationship of 0-fc- , in which about 20% of high band is eliminated based on the sampling rate, 2fc*. The sam¬ pling rate between luminance and chrominance signal is approx. 5:1 in consideration of their bandwidth.

Thus, providing that the sampling rate of chrominance signal is fixed to 1/5 of that of the luminance signal, the sampling rate of the chrominance signal will be; 2fc* x 1/5 = 0.4 fc*, therefore the signal bandwidth including the chrominance signal fc* is made based on the sampling rate of 0.4 fc*. The above-mentioned luminance and chrominance signal is modulated into two carrier frequency having difference of ΔF(ΔF = 570 f _H - 227.5 f _H , i.e. fc* -fc) to make a modu¬ lated signal which is compatible with the conventional NTSC system in the interleaved region and capable of transmitting high resolution picture signal.

The above modulation scheme renders luminance signal wider signal bandwidth than the NTSC system, namely, 0-

7. MHz rather than 0-4.2 MHz, and increasing the resolu¬ tion in the horizontal direction. However, since the picture signal is displayed by the one-line scanning, there is still finite number of lines in the scanning raster, which limits the image clarity or resolution in the vertical direction.

DISCLOSURE OF THE INVENTION

In view of the foregoing, the object of present inven¬ tion is to provide a method for modulation and deraodula- tion of multiplexed color picture signal so as to increase resolution in the vertical direction by using synchronous raster scanning of 2-Line electron beam, while maintaining the same horizontal resolution as in the conventional NTSC system by multiplexing the Y signal of 0-7.2 MHz bandwidth from the Y/C signal into 2 line of Y signals, which is divided in the demodulation process into two Y signals that make 2-Line scanning.

The another object of the present invention is to provide a means for display the multiplexed 2-Line elec- tron beam in color CRT having two line of cathode array or common R, G, B cathode and two grid electrode for Y signals.

The other object of the invention is to provide a method for modulation and demodulation of a multiplexed color picture signal which is applicable in recording and reproducing in the Video Tape Recorder.

The other object of the invention is to provide a method for modulation and demodulation of a multiplexed

color picture signal which is applicable in Video Disk Player or Fiber Optic transmission.

The other object of the present invention is to pro¬ vide a method' for modulation and demodulation of a multi- plexed color signal which is applicable in SHF or satel¬ lite communication.

In an embodiment of the method of modulation and demodulation of color picture signal, there is provided a step of the modulation comprised of producing a YQW signal, having double bandwidth of Y signal, by alternately sampled Y and Y. signals based on multiplied by 2 color subcarrier, 2 fc* as divisional signal, multiplexed from the color composite signal Y/C through 2 line input of multiplexer (11) , modulating the YQW signal through low pass filter (12) having 0-7.2 MHz of bandwidth to produce a multiplexed Yy signal producing a modulated color signal from the color difference signal (R-Y) , (B-Y) into color subcarrier c*)^ and having phase difference of 90° through mixers

(13), (14) and adder (15), to have the bandwidth of 7.5-

9.6 MHz through band pass filter (16), modulating audio signal through FM modulator (17) and band pass filter (18) to produce FM audio signal having 9.8 MHz - 10.0 MHz, and obtaining a multiplexed color picture signal YQ/C by adding the YQ signal, modulated c signal, FM audio signal and burst signal, having 0-10.0 MHz bandwidth.

Also, there is provided a step of demodulation com¬ prised of, demodulating the YQ/C signal to obtaining Y signal through low pass filter (28) by sampling the YQ signal on the basis of the color subcarrier 2fc* through low pass filter (25) and sampling circuit (27),

Restoring the upper side band of 10.7 MHz - 17.9 MHz through mixer (30) and band pass filter (31) after obtain¬ ing the lower side band signal by subtraction of Y signal in subtracter (29), obtaining the YQW signal by adding the YQ signal and the upper side band signal in adder 32, the signal band¬ width are located in 0-7. MHz and 10.7-17.9 MHz in which 7.2 MHz - 10.7 MHz bandwidth is not restored, restoring Y and Y^ signal eliminated high band signal more than 7.2 MHz through low pass filter (34), (35) after dividing the Y and Y^ signal in divider (33) from the YQW signal, and demodulating the C signal and audio FM signal by reverse processing of their modulated signal process,

Thereby enable the multiplexed color picture signal to be displayed in 2-Line scanning with increased vertical resolution.

The above mentioned YQW signal is restored from the YQ signal by using digital filter comprised of unit delay

(Z ^~ ) having unit time delay characteristics, multiplex and adder to produce a quasi YQW signal having 0-7.2MHz

and 10.7-17.9MHz bandwidth.

Further, the YQ/C signal is demodulated in 0-10.0 MHz of signal bnndwidt.h includes the step of modulating t f YQ/C signal in the mixer (66) by carrier frequency of local oscillator (65) , obtaining 2 channel modulated signal of 12.0 MHz bandwidth through band pass filter (67) , demodulating the 2 channel modulated signal to YQ/C signal through local oscillator (72) , mixer (73) and band pass filter (74) .

Also, the method of this invention can be applied to recording and reproducing multiplexed color picture signal in VTR including the step of; separating the Y signal, C signal and audio signal from 0-10.0 MHz YQ/C signal through low pass filter (80) and band pass filter (81), (82), modulating each of the above signals through FM modu¬ lator (83) , mixer (85) , FM demodulator (90) , 1H sampling circuit (88), band pass filter (84), (87) and low pass filter (91), applying the modulated YQ/C signal generated in adder (89) and audio signal to a video head in VTR, demodulating the modulated YQ/C signal into the origi¬ nal YQ/C signal by a reverse processing step from the video head in VTR, thereby enable the multiplexed color picture signal to be displayed in 2-Line scanning.

Further features and advantages of the invention will become more readily apparent from the following detailed

description when taken in conjunction with the accompany¬ ing drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram which shows a spectrum of compos- ite picture signal, in which (A) shows a distribution of Y/C signal and (B) shows a frequency distribution of modulated Y/C signal.

FIG. 2 is a diagram similar to Fig. 1, in which

(A) shows a frequency distribution of multiplexed YQ/C signal.

(B) shows a frequency distribution of 2-channel modulation scheme by mean of multiplexed YQ/C signal.

(C) shows a frequency distribution of the modulated signal to be supplied with a video head of VTR. (D) shows a frequency distribution of the modulated signal to be supplied with a fiber optics or a Video Disk Player.

FIG. 3 is a diagram which shows a frequency distribu¬ tion of the modulated signal to be used in SHF Band or satellite communication.

FIG. 4 is a diagram for illustrating relevant, signal and principle of the present invention in which,

(A) is for analyzing YQW signal.

(B) shows a waveform of YQW signal. (C) is for analyzing Y signal for modulating Y/C signal into 1-channel modulated signal. (D) shows a frequency spectrum for explaining a method of

demodulating the 1-channel modulated signal to Y/C signal.

FIG. 5A is a schematic block diagram of modulation circuit for YYC signal. FIG. 5B is a schematic block diagram of demodulation circuit for modulated YQ/C signal.

FIG. 5C is a schematic of demodulation circuit for modulated YQ/C signal comprising digital filter.

FIG. 5D is a schematic of driving circuit for a color electron gun arranged in two line.

FIG. 5E and 5F are a schematic diagram each of which shows inter connection between drivers of Y and YY signal of two-line electron beam, drivers of R, G, B signal and corresponding electrodes in Cathode Ray Tube. FIG. 6A and 6B are schematic diagrams which show modu¬ lation and demodulation steps for multiplexed Y'Q/C signal in 2-channel.

FIG. 7A and 7B are schematic block diagrams which show modulation and demodulation circuits for multiplexed Y ^* Q/C signal to be used in recording and reproducing in VTR.

FIG. 8A and 8B are schematic block diagrams similar to FIG. 7, which are applicable to a Video Disk Player or a fiber optics.

FIG. 9A and 9B are schematic block diagrams similar to FIG. 8, which is applicable to a SHF band or satellite communication.

FIG. 10A and 10B are schematic block diagrams which

show modulation nnd demodulation steps for Y/C signal in 1-channel.

FIG. 12B is a partly broken away perspective view which show another embodiment of 2-Line arrangement of cathode array in accordance with the present invention.

FIG. 13A and 13B are schematic diagram of AD/DA con¬ verter which has characteristics of "Y - YL . (1 + ^g-) " in the multiplexed YQ/C signal of the invention.

FIG. 14A and 14B are schematic diagram of AD/DA con- verter which exhibit characteristics of " Y - log -^ ~ • ^ + — YΔ _Q — ) " in the multiplexed YQ/C signal.

FIG. 15 is a schematic diagram which shows overall step for displaying multiplexed YQ/C signal into color

CRT.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to a method for produc¬ ing a multiplexed Y'Q/C signal through modulating luminance and chrominance signal (hereinafter called YVC signal) which is compatible with conventional NTSC composite picture signal, and for demodulating the YQ/C signal to be separated into two line signal which enable synchronous 2-Line scanning, thereby increase double vertical resolu¬ tion in raster.

Now, with reference to Fig. 5A and 5B, there are shown circuit block diagram for modulating and demodulating the multiplexed YQ/C signal, respectively. In Fig. 5A, the modulating circuit for the multiplexed Y ^" Q/C signal in-

eludes luminance Y signal modulating section composed of multiplexer 11 and low pass filter 12 for multiplexing modulation by color subcaliber of 2 fc*, color, C signal modulating section composed of mixer 13, 14, adder 15, and band pass filter 16 for modulating the subcarrier fc* to have 90° phase difference between color difference signal R-Y and B-Y", audio signal modulating section for obtaining modulated audio signal through FM modulator 17 and band pass filter 18, color subcarrier generating section com- posed of color subcarrier oscillator 19, phase shifter 20 and multiplier 21, and burst signal section for generating color burst through sampling circuit 22 and band pass filter 23.

In this arrangement, upper line of Y_ signal and lower line of '^ signal are supplied to the two inputs of multi¬ plexer 11 of Y' signal modulating section, and based on double multiplied color subcarrier 2 fc* from the color subcarrier oscillator 19, the multiplexer 11 produce a Y ^' QW signal as shown in Fig. 4 (B) . This YQW signal is- supplied to the low pass filter 12 and the output signal YQ is obtained, having 0-7.2 MHz band¬ width.

Modulated C signal is produced through mixer 13, 14, adder 15 and band pass filter 16, having 7.5 MHz - 9.6 MHz bandwidth, from the color difference signal R-Y ^" and B-Y". Also, modulated audio FM signal is produced through fre¬ quency modulator 17 and band pass filter 18 having 9.8 MHz - 10.0 MHz Bandwidth. Burst signal is obtained by sepa-

rating color subcarrier fc* from 1H of phase synchronizing signal and filtering by band pass filter 23.

The modulated Y ^' Q signal, C signal, FM audio signal and burst signal are summed in adder 24 to produce a multi- ⁵ plexed YQ/C signal.

In the multiplexed YQ/C signal, since Y ^* Q signal is made by double rate sampling than the Y signal of Y/C signal, it includes double video signal. However, com¬ paring Y/C signal in Fig. 1 (A) with Y ^' Q/C signal in Fig. 2 10 (A) , they are in the same frequency bandwidth. Thus, difference signal from the Y and Y. signal is appeared as phase modulated component in 0-7.2 MHz bandwidth, and the YQ signal is compatible with Y signal, with improved phase transfer characteristics. On the other hand, in order to ^• '-5 be divided again into Y _& and Y. signal, it is necessary to restore the original YQW signal. This is accomplished by using YQ signal characteristics in phase modulation that has components of difference between YQW signal and Y ^" , Y signal in lower side band. 0 Also, since the YQW signal is produced by the Y and Y. signal based on divide signal of 2 fc*, the YQW signal is divided by 2 fc* signal and can be divided into original Y ^* _a and Ytø signal.

However, YQ/C signal composed of YQ signal which has o-7.2 MHz bandwidth will be restored to YQW signal b means of low pass filter 12 in Fig. 5 (A) to restore eliminated band, or operation of difference sampling rate

of Y ^' Q signal. The method for restore the eliminated frequency band can be found that the Y'QW signal can, as shown in Fig. 5 (B) , be expressed in summation of phase modulation component from the difference of Y and Y^ signal with signal fc* as the central and amplitude modu¬ lation component from the summation signal of Y ^" _a and Y^ signal and having bandwidth of 0-fc* in the baseband.

As mentioned before, Y signal and Y^ signal are in the ϋ-fc* bandwidth with sampling rate of 2 fc* respec- tively, and these signal have phase difference of 90° at the signal bandwidth of color subcarrier. Accordingly, the YQW signal made by alternately sampling of the Y„ and Ytø signal has bandwidth of 0-2fc* with baseband amplitude modulation component (Y portion of Fig. 4 (A) ) from summa- tion of Y _a and Y^ in 0-fc* bandwidth and phase modulation component (YH, YH ^" portion of Fig. 4(A)) from subtraction of Y ^* _a and Y' _b signal with central frequency of fc*, and thereby obtain a lower side band of 0-fc* (YH- portion of Fig. 4 (A) ) and a upper side band of fc* - fc*, which are of reverse phase relation due to the phase modulation. In that YQ/C signal is transmitted only a portion of the AM component composed of Y and YY signal summation through low pass filter 12 from Y(YQ) signal of 0-7.2 MHz Bandwidth, and a portion of phase modulation component in lower side band (at Fig. 4 (A) , Portion YH~) composed of difference signal of Y and Y _h signal in 0-fc* handwidth, thus it is impossible to restore the YQW signal if the upper side band of the phase modulation signal is re-

stored.

Fig. 5 B illustrates a block diagram of demodulation circuit for Y"Q/C signal of the present invention, which includes Y" signal demodulating section comprised of low pass filter 25, sampling circuit 27, low pass filter 28, subtractor 29, mixer 30, band pass filter 31, adder 32, divider 32, and low pass filter 34, 35 for separating Y'Q signal from YQ/C signal, C signal demodulating section composed of mixer 6, 37 and low pass filter 38, 39 for separated C signal from band pass filter 26, burst signal demodulating section composed of sampling circuit 40, band pass filter 41, color subcarrier oscillator 42, phase shifter 43 and multiplier 44, and audio signal demodulat¬ ing section composed of frequency demodulator 45 and low pass filter 46 for demodulating the modulated audio signal separated through band pass filter 17.

In this circuit arrangement, the Y signal demodulation section operates such that low pass filter 25 produces Y" <a signal of 0-7.2 MHz from the YQ/C signal. The Y _& signal is supplied with sampling circuit 27 and low pass filter 28 to produce the Y signal (Fig. 4 (A) ) by sampling rate of 2fc* based on the sampling signal located in midway of Y ^' _a and Y^ signal. This Y signal is sub¬ tracted (Y-YQ) in the subtractor 29, and lower side band signal of 0-7.2 MHz from the phase modulation signal by the difference signal of and Y^ is obtained, and there¬ after supplied with mixer 30 and band pass filter 31 to

restore upper side band from the phase modulation compo¬ nent by the signal difference of Y and Y ^' _b signal 10.7 MHz 17.9 MHz bandwidth based on the carrier frequency of fc*. The restored upper side band and the original Y ^* _a signal is summed in adder 32 to produce YQW signal having non-restored bandwidth of 7.2 MHz-10.7 MHz from 0-7.2 MHz and 10.7-17.9 MHz bandwidth signal, this YQW signal is divided into Y signal component and Y^ signal component by divider 33 with dividing signal of 2fc*.

The loss of signal in 7. -10.7 MHz is related to separated Ye ₀ l signal and its signal more than 7.2 MHz, thus

Y ^" _a and ^' tø signal having bandwidth of 0-fc* are supplied with each band pass filter 34, 35 to eliminate high signal component more than 7.2 MHz and thereby division of Y and Y _b signal having 0-7.2 MHz bandwidth is completely finished.

In Fig. 5 (c) , there is shown another embodiment of demodulation circuit for YQ/C signal, which is similar to Fig. 5(B) except for incorporating digital filter section comprised of unit (Z ^-i ) , Multiplier (MUD and Adder (ADD) connected serially at end of low pass filter 25. In this embodiment, the provision of the digital filter operates so as to offset the effect of low pass filter in Fig. 5 (A) , and thereby original Y'QW signal can be restored.

In order to enable the demodulated Y and YY signal to drive CRT, as shown in Fiε. 5 (D) to (F) , there is provid¬ ed a low pass filter 60 for obtaining low band component

of Y signal, a R, G, B from the separated R-Y ^" and B-Y si ^g ¬ nal, Cathode Ray Tube having 6 cathode electrode ' ^KR _a ' KG _a , KB _& , KR _b , KG _b , B _b ) to produce 2-Line electron beam through CRT drive stage 47-52 or having three common cathode electrode (KR, KG, KB) and two grid ' ^G ι _a » ^G lb ^> supplied with separated R, G,B color signal and two lumi¬ nance Y , Y signal respectively to allow 2-Line scanning. Thus, in case of the CRT having 2-Line R, G, B cathode array is required six drive circuit 47-52 connected in combination of three R, G, B signal line and two Y ^' _a , Y _b signal line as shown in Fig. 5 (E) . On the other hand, the CRT having construction of common three R, G,B cathode and two separated grid OG, , G, _b is supplied with each of the R, G,B signal and Y , Y^ _b signal, after they are con- verted into required electrical potential and amplitude to be applied to CRT.

Since the YQ/C signal used the same signal bandwidth as that of the Y/C signal in the aforementioned Korean patent application no. 11342/89, it has compatibility to each other and the YQ/C signal was multiplexed by the 2- Line Y signal, Y and Y _b which can be restored and allowed to display in 2-Line scanning thus having double vertical resolution of TV image.

As mentioned before, the Y/C signal of my prior Korean application 11342/89 was obtained by sampling based on color subcarrier fc* (which has characteristics of 570 x f _j .) and transmitted C signal, however, in this embodiment

of present invention there is provided a high resolution signal whose Y" signal bandwidth is 0-7.2 MHz, more wider than conventional 0-4.2MHz, and the C signal is regulated to have the same bandwidth as the conventional NTSC system based on carrier frequency of fc*; thus the Y ^" and C signal bandwidth are determined not to be interleaved and the noise occurs from the cross interference of prior art is initially prevented.

Also, since the Y/C signal can be modulated to signal as illustrated in Fiε. 1 (B) which is compatible with the modulated signal of the conventional NTSC system, it is possible to obtain a modulated signal of Fig. 1 (B) capable of transmission of high resolution picture signal using the conventional NTSC broadcasting network. Fig. 6 illustrates a modulation and demodulation circuit" block diagram in which the YQ/C signal according to this invention is applied to 2-ehannel bandwidth TV transmission. In this circuit, arrangement, the Y ^T Q/C signals demodulated in 0-10, 0 MHz of signal bandwidth includes the step of modulating the YQ/C signal in the mixer 66 by carrier frequency of local oscillator 65, obtaining 2 channel modulated signal of 12.0 MHz bandwidth through band pass filter 67, demodulating the 2 channel modulated signal to Y ^' Q/C signal through local oscillator 72, mixer 73 and band pass filter 74.

Fie. 7 illustrates the construction of modulation and demodulation of the Y ^" Q/C signal of the present invention, which is applicable to VTR for recording and reproducins

the multiplexed color, picture signal.

In this embodiment, the operation of the modulation and demodulation circuit include the method comprising the step of; separating the Y" signal, C signal and audio signal from 0-10.0MHz YQ/C signal through low pass filter 80 and band pass filter 81, 82, modulating each of the above signals through FM modu¬ lator 83, mixer 85, FM demodulator 90, 1H sampling circuit 88, band pass filter 84, 87 and law pass filter 91, applying the modulated YQ/C signal generated in adder 89 and audio signal to a video head in VTR, demodulating the modulated YQ/C signal into the origi¬ nal YQ/C signal by a reverse processing step from the video head in VTR, thereby the multiplexed color picture signal can be displayed in 2-Line scanning.

Further, referring to figure 8, there is shown a modulation and demodulation circuit block diagram which is applicable to a Video Disk Player and fiber optic trans¬ mission line.

It this circuit arrangement, the operation and process of the modulation and demodulation comprising the step of; separating the YQ/C signal into Y signal, C signal and audio signal through low pass filter 80 and respective band pass filter 81, 82, modulating the said Y, C, audio signals through the FM

modulator 83, mixer 85, FM demodulator 90, sampling cir¬ cuit 88 for sampling color subcarrier of 9/8 fc* from oscillator 86 with sampling base of 1H period, band pass filter 84, 87 and low pass filter 91, obtaining a PWM modulated signal on the base of vary¬ ing duty width by routing the respective modulated YQ/C signal and audio signal summed in summing circuit 89 to slice circu t 108, transmitting the modulated PWM signal to optical transducer 109, 110 to achieve an electric to optic change for a Video Disk Player and Fiber Optics, shaping the electrical signal by routing the electric-optic signal to slice circuit 113 for inverting the optical signal to electric signal, demodulating the modulated YQ/C signal to obtain original YQ/C signal by reversing process of the modula¬ tion step.

Referring to Fig. 9 there is shown a modulation and a demodulation circuit block diagram in which the YQ/C signal is applied to a SHF or satellite communication system.

The operation and method of the modulation and demodu¬ lation circuits are similar to that of in Fig. 5, except for the process comprised of, transmitting the modulated YQ/C signal and audio signal via a satellite antenna 126 by routing the Y'Q/C signal and audio signal to local oscillator 118, mixer 108, band pass filter 122, local oscillator 123, mixer 124

and band pass filter 125, receiving and demodulating the transmitted signal through band pass filter 127, local oscillator 128, mixer

129, band pass filter 130, frequency divider 131, band pass filter 132 _r local oscillator 133, mixer 134 and band pass filter 135, restoring the demodulated signals to obtain original YQ/C signal and audio signal through slice circuit 113 by reverse process of said step of recording or transmission in VDP and fiber optics.

With reference to Fig. 10, there is shown a circuit block diagram for modulating the Y/C signal to 1-channel modulated signal and demodulating the 1-channel modulated signal into Y/C signal. In this circuit arrangement, the operation and the process thereof comprising the step of, obtaining a Y signal, i. e. Y ^" 2 ^~ signal through band pass filter 141 having 4.2-7.2MHz, summing the Y ^* 2 ^H signal, C signal and audio FM signal in a summing circuit 147 to produce 1-channel modulated signal having 4.2-10.0MHz bandwidth, wherein a mixer 144 for converting the modulated Y signal of 0-4.2MHz with ΔF carrier frequency into signal bandwidth of 4.2-9.6 MHz and a sampling circuit 142 having sampling rate of fc* is provided, separating the 1-channel modulated signal into a picture signal of 4. -9.6MHz bandwidth through band pass

filter 150, 151 and a audio FM signal, obtaining separated ΔF signal component of band pass filter (150, 151) and fc* signal component through 1H sampling circuit 152, and providing continuous and stable oscillation of the ΔF and fc* signal by means of oscilla¬ tor 155, 156 respectively, and obtaining 2fc* signal through multiplier 157, providing Y ~2 signal by routing the signal from the band pass filter 150 to mixer 158, low pass filter 159, sampling circuit 160 and low pass filter 161, providing Y ^' 2 ^H signal by routing the signal from band pass filter to 2fc* sampling circuit 166 and band pass filter 167, restoring a lower side band signal (Y2* ) through band pass filter 169 after modulating the Y 2 ^H signal by fc* signal through mixer 168, obtaining color signal with subcarrier fc* by routing the Y ^" 2 ^" signal to mixer 162, band pass filter 163 and offsetting the Y ~Z signal through subtractor 164 from Y ^" 2 ^" signal including the C signal, providing a complete Y/C signal by routing the Y ^" _T signal, Y ^" 2 , Y ^" 2 ^H and C signal to summing circuit 174, demodulating the modulated audio signal through band pass filter 151, FM demodulator 172 and low pass filter 173.

The spectrum of the 1-channel modulated Y"/C signal is shown in Fig. 11 (B) as compared with the frequency spec¬ trum of Y/C modulated signal shown in Fig. 11(A).

Referring to Fig. 12, there is provided six cathode array (KG _a , KB _& , KR _& , KB _b , KG _b and KR _b > in 2-Line arrange¬ ment, each of which are connected via drive stage in combination of R, G,B signal line and Y' _a , Y signal line, thus allow to produce 2-line electron beam.

In the alternative embodiment as shown in Fig. 12 (B) , there is provided three cathode (KR, KG, KB) and two grid (Gl _a , Glfe' ^for supplying the R, G,B signal and Y ^' _a , Y _b signal respectively. Now, referring to Fig. 13 to Fig. 15, there are shown a display means capable of 2-line scanning of the multi¬ plexed Y/C signal in which the means comprised of, A/D converter for converting demodulated YQW signal and B-Y", R-Y signal to a digital data signal, and three-state buffer 223-236,

D/A converter for converting digital data to analog data, multiplexer 220 for selecting input picture signal and memory picture signal by applying WE signal. divider 221 for separating Y ^" and Y _b signal by apply- ing 2fc* signal, frequency divider 231 for processing double quantity of color resolution by applying 0.4 fc* signal, serial enable shift divider 229 for making 1 block of 32 bits from the output data of said A/D converter and 3- state buffer, 233-236, double port RAM 232 for storing and transmitting sequentially divided said block signal.

The D/A and A/D converter comprised of a D/A converter

(180-183) for providing each of 4 bit YΔ data, Y^ data, R-Y" data and B-Y data, a multiplier 186 for converting Y^ data to Y signal, a summing circuit and 1/8 multiplier for

Y converting the Y ^" data to 1 + _j signal, multiplier 187, 188 for converting the R-Y and B-Y data to analog R-Y ^' and B-Y ^" signal, A/D converter 191 for converting said Y signal to Y ^" _L data through law pass filter 190, and D/A converter 195, function generator 193, multiplier 194, 196, summing circuit 195 and A/D converter 197, 200, 201.

Further, the YΔ data is converted to Y' signal by rout¬ ing the Y ^' Δ data to D/A converter 180, 1/8 multiplier 184, adder 185 and multiplier 204, and the Y", data is converted to 2 ^{YL 4} signal through D/A converter 181 and 2^ func¬ tion generator 203, the R-Y ^" and B-Y data is converted to R-Y and B-Y ^" signal through D/A converter 182, 183 and multiplier 205, 206. Wherein said Y signal is converted

YL to Y^ signal through low pass filter 190, logyAϊ-" function generator 207 and A/D converter 208, the YΔ signal is converted to Y ⁷ Δ data by routing the Y, signal to D/A converter 209, multiplier 210, 211, adder 212, 8-multipli- er 213 and A/D converter 214, the R-Y and B-Y ^" signals are converted to B-Y and R-Y data through multiplier 215, 216 and converter 217, 218 respectively.

The invention has been described with reference to exemplary embodiments, but variations within the spirit and scope of the invention will occur to those skilled in the art.