JPS6330087A - Transmission system for television signal - Google Patents

Abstract

PURPOSE:To reproduce both still and moving pictures with high accuracy by multiplexing a prescribed coefficient to a high-frequency luminance signal subjected to frequency conversion and adding to a couple of chrominance signals alternately at each line to separate the high-frequency luminance signal by the signal processing in the same field at the reception side. CONSTITUTION:An output of an adder 6 of a TV receiver RN is fed to a matrix circuit 71 and outputs of adders 5, 7 are fed directly to fixed contact points 72a, 74b of changeover switches 72, 74 respectively and fed to other fixed contact points 72b, 74a via 1H delay lines 73, 75 and outputs of moving contact points 72c, 74c are fed to the matrix circuit 71. The output and a luminance signal output of a Y/C separation circuit 3 of the TV receiver RN are fed to a subtractor 76. The output of the subtractor 76 is fed to fixed contact points 79a, 79b of the changeover switch via coefficient multipliers 77, 78 and an output of the moving contact 79c is fed to four coefficient multipliers 81-84 and a high-frequency conversion circuit 85. The output of the high-frequency conversion circuit 85 is fed to three adders 64-66. Then the output of the coefficient multipliers 81-84 is fed to the adders 64-66 via a changeover switch 86 as shown in figure and its output is fed to a receiver 2.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Field of industrial application B. Overview of the invention C. Prior art D. Problem to be solved by the invention E. Means for solving the problem (Fig. 1) F. Effect G. Example G1 Encoder of one example (Fig. 1) Figure 1) Configuration of decoder of G2 embodiment (Figure 2) Gl NTS
Compatibility with the C system (Fig. 2) Decoder operation of the G4 embodiment (Fig. 2) H Effect of the invention A Industrial application field The present invention is a high-precision system that is compatible with the current NTSC system. This invention relates to a method for transmitting television signals again.

B. Summary of the Invention The present invention provides a television signal transmission method in which a high-band luminance signal is converted to a low-band signal and multiplexed with a luminance signal within a predetermined band and a carrier color signal. By multiplying each color signal by a predetermined coefficient and adding it alternately for each line to each of the pair of color signals that form the carrier color signal, it is possible to easily separate the high-range luminance signal and improve compatibility with the current method. This makes it possible to obtain high-definition reproduced images while maintaining the image quality.

C. Conventional technology In order to improve the definition of television images based on the current NTSC system standard, a ``proposal for a high-definition TV system with complete communication performance'' was published in the Institute of Electronics and Communication Engineers technical report CS.
83-61 (July 1983), etc.

First, while referring to Figures 3 to 6,
The signal of this high-definition TV system, which is also called a tended definition TV system, will be explained.

As is well known, a wide frequency band is required to transmit high-definition information in the horizontal direction. In the EDTV system, as shown in Figure 3, the NTSC system's 4.2MHz
A higher range than the luminance signal Y up to, for example, 4.0 to 6.
High-definition information (high-band luminance signal) in the 0MHz frequency band Y
H is low-frequency converted (shifted down) and multiplexed into a band of, for example, 2.2 to 4.2 MHz within the frequency band of the NTSC system. Hereinafter, the downshifted high frequency luminance signal may be expressed as YH8 to distinguish it from the original high frequency luminance signal YH.

By the way, in the NTSC system, the color sub-law transmission frequency fsc is selected to satisfy a specific condition, and the spectrum of the luminance signal Y and the spectrum of the color signal C are frequency interleaved as shown in FIG. 4A. There is a relationship between

However, if you look at the figure in detail, you will see that the spectrum of the color signal C is inserted into every other gap in the spectrum of the luminance signal Y, and there is still an empty gap in every other gap. Therefore, in the EDTV system, as shown in Figure 4B,
The downshifted high frequency luminance signal VHS is inserted into this empty gap.

The micro frequency gap in FIG. 4 is two-dimensionally represented in the time-vertical three frequency domain shown in FIG. That is, the color signal C of the NTSC system is placed in the second and fourth quadrants, and the high-band luminance signal '/Hs of the EDTV system is placed in the first and third quadrants.

Furthermore, in order to arrange the spatio-temporal frequency spectrum of the high-band luminance signal yH as shown in FIG. 5, the phase of the subcarrier for downshifting the high-band luminance signal YH is as shown in FIG. It is necessary to set the scanning lines having YHB subcarriers of the same phase to descend every field.

Next, with reference to FIGS. 7 to 9, the E
A circuit configuration for multiplexing and separating the high-band luminance signal YH of the DTV system will be described.

An example of the configuration of a conventional EDTV encoder and decoder is shown in FIG.

In FIG. 7, (lO) indicates the encoder as a whole, and the wideband three primary color video signal Ri from the TV camera (1)
v, Gw, and B- are supplied to a matrix circuit (11) to form a wideband luminance signal Yw from 0 to 6MHz and a pair of wideband color difference signals (R-Y)w and (B-Y). Ru. Both band color difference signals (R-Y)w and (B-Y)w are band-limited by low-pass filters (12) and (13), respectively, and are converted into NTSC color difference signals R-Y and B-.
It becomes Y. These color difference signals R-Y and B-Y are transmitted through a transformer (1
4) from the oscillator (15) to the modulator (14)
quadrature two-phase modulation of the color subcarrier (fsc) supplied to
Carrier color signal C (2.1~4.2MH) from the modulator (14)
z) is fed to an adder (16).

On the other hand, the wideband luminance signal Yw is commonly supplied to a high-pass filter (17) and a low-pass filter (18), and is separated into a high-pass luminance signal YH and a luminance signal Y.
20), the high-frequency luminance signal YH is downshifted and multiplexed with the luminance signal Y. Multiplex circuit (20)
The details will be described later. The output of the multiplex circuit (20) is sent to the adder (
16) and is combined with the carrier color signal C, and the HDTV
A signal is led out to an output terminal (19).

(30) shows the decoder as a whole, and the encoder (1
0) is commonly supplied to the low-pass filter (32) and the high-pass filter (33) from the input terminal (31) of the decoder (30), and the high-pass filter (33)
The output of is supplied to the separation circuit (40).

Details of the separation circuit (40) will be described later. Separation circuit (40)
The carrier color signal C (2.1 to 4.2MIIz) is supplied from the demodulation circuit (34) to the color demodulation circuit (34).
The sets of color difference signals R-Y, G-Y and B-Y are supplied to a set of adders (35), (36) and (37).

Note that the green difference signal G-Y is formed from the red difference signal RY and the blue difference signal B-Y according to the following equation.

G-Y=-0,51(RY)-0,19(B-Y)
Frequency band lower than carrier color signal C (0 to 2.1M H
A low-pass luminance signal YL of z) is supplied from a low-pass filter (32) to an adder (38). From the separation circuit (40) to this adder (38), 2.1 to 4
．． A mid-range luminance signal YM in a frequency band of 2 MHz is directly supplied. Further, the high-frequency luminance signal YHB shifted down from the separation circuit (40) is supplied to the high-frequency conversion circuit (39), and the high-frequency conversion circuit (shifting The high-frequency luminance signal YH restored by the high-band luminance signal YH (up) is supplied to an adder (38). As a result, from each luminance signal YL I YM I YH to O~6
The broadband luminance signal Y- of M fiz is recovered and fed from the adder (38) to a set of adders (35), (36) and (37). Each adder (35) to (37)
, the three primary color signals R+Y of the EDTV system are obtained from the color difference signals R-Y, B-Y, G-Y and the broadband luminance signal ¥-.
H, G + YH and B + YH are formed and EDTV
It is supplied to the image receiving hall (2) of the system.

FIG. 8 shows an example of the configuration of the multiplex circuit (20). In this FIG. 8, (21) is the ↑ film width modulator, and the terminal (2
The output of the 1/2 frequency divider (22), which is supplied with the high frequency luminance signal YH from the terminal (0a) and is supplied with the color subcarrier as a carrier wave for downshifting the high frequency luminance signal YH, is connected to the terminal (0a). 20f) through the switch (23),
Supplied. This increases the frequency band from 4.0 to 6.0.
The high frequency luminance signal YH of Ml1z is f SC/2 * 1.
It is modulated at a frequency of 8MHz. The output of the modulator (21) is fed to a bandpass filter (24) to
The lower MHz sideband is separated and downshifted. The downshifted high-frequency luminance signal YH5 and the luminance signal Y from the input terminal (20b) are sent to the adder (25).
The signal is multiplexed at the output terminal (20c) and output to the output terminal (20c).

In addition, in order to invert the phase of the carrier wave for each field,
The output of the frequency divider W (22) is directly supplied to one fixed contact (23a) of the switch (23), and the other fixed contact (
23b) is supplied via the inverter (26), and the movable contact (23c) of the switch (23) is
a second 1/2 frequency divider (27) to which the vertical drive signal is supplied;
Controlled by the output of
a) and (23b) alternately. Although not shown, the first frequency divider (22) is phase-locked by the horizontal drive signal.

FIG. 9 shows an example of the configuration of the separation circuit (40). In this FIG. 9, (41) is 262H by field memory.
a delay line comprising first and second subtracters (42) and (
43), the current field signal is supplied from the terminal (40i). In the first subtractor (42), the previous field signal output from the delay line (41) is subtracted from the current field signal to obtain a downshifted high-band luminance signal YH5. Further, the output of the delay line (41) is passed through the IH delay line (44) to the second subtracter (43).
) and is subtracted from the current field signal to obtain the carrier color signal C.

In addition, YH5 and C separated in this way are connected to a separation circuit (4
0), the mid-range luminance signal YM is separated.

D Problems to be Solved by the Invention However, as mentioned above, in the EDTV system, in order to separate multiplexed high-definition information on the receiving side, three-dimensional signal processing is performed using field memory, etc. However, there were problems in that the structure was complicated and the manufacturing cost was high.

In addition, since field memory etc. are used, in the case of videos,
The problem is that separating high-definition information requires extremely difficult technology called motion adaptive processing.

In view of this, an object of the present invention is to provide a high-definition television signal transmission system that is easy to decode while maintaining compatibility with current systems.

E. Means for Solving the Problems The present invention provides a television signal transmission system in which a high-band luminance signal outside a predetermined frequency band is frequency-converted and multiplexed with a luminance signal and a carrier color signal within a predetermined frequency band. In this television signal transmission system, frequency-converted high-frequency luminance signals are each multiplied by a predetermined coefficient and added alternately for each line to each of a pair of color signals forming a carrier color signal. be.

F Effects According to this configuration, while maintaining compatibility with the current system, high-frequency luminance signals can be easily separated by signal processing within the same field on the receiving side, and both still images and moving images can be processed. High-definition reproduced images can be obtained.

G. Embodiment Hereinafter, an embodiment of the television signal transmission system according to the present invention will be described with reference to FIGS. 1 and 2.

G1 one embodiment encoder FIG. 1 shows the configuration of an encoder according to an embodiment of the present invention.

In FIG. 1, parts corresponding to those in FIG. 7 are designated by the same reference numerals, and some explanations will be omitted.

In FIG. 1, numeral (50) is a low-frequency conversion circuit, which includes appropriate local oscillators, filters, and the like. In this example, since the signals are processed within the same field, there is no need to consider frequency interleaving of the high-frequency luminance signal (there is no special requirement for the local oscillation frequency.
0) is supplied with a high frequency luminance signal Y from a high frequency filter (17), and the output YHD of the low frequency conversion circuit (50) is supplied to a movable contact (51c) of a changeover switch (51). double-sided constant contacts (51a) and (51b)”
) are connected to coefficient multipliers (52) and (53), respectively. Low-pass filter (18) for separating the luminance signal
The output of is directly supplied to the adder (16), and a pair of low-pass filters (16) are used to limit the band of the color difference signal.
2) Adders (54) and (55) are inserted between (13) and the quadrature two-phase transformer (14), and the outputs of the coefficient multipliers (52) and (53) are connected to the adder ( 54) and (55), respectively.

The operation of the encoder of FIG. 1 is as follows.

For example, 4.2 to 660M by the low frequency conversion circuit (50)
High-frequency luminance signal Y in the Hz frequency band is 0 to 1.8M
) Iz frequency band. Hereinafter, this downshifted high-frequency luminance signal will be expressed as YHD,
This signal is distinguished from the original high-frequency luminance signal YH and the conventional shift-down high-frequency luminance signal VH8.

The movable contact (51c) of the switch (51) is connected to one fixed contact (51a) on a certain line La,
On the next line Lb, the coefficients m and n (0 <m, n1l), and in both adders (54) and (55), a pair of color difference signals R-
Depending on the connection state of the switch (51), a pair of color difference signal components (RY)a, (RY)b and (B-Y) as shown below are added to )a,
(B-Y)b is obtained.

That is, when the movable contact (51c) of the switch (51) is connected to the negative fixed contact (51a), both adders (
The outputs of (54) and (55) are as shown in the following formula 0, respectively.

Also, when the movable contact (51c) of the switch (51) is connected to the other fixed contact (51b), both adders (51c)
The outputs of 4) and (55) are as shown in the following equation 0, respectively.

The color difference signal components as described above are alternately supplied to the converter (14) line by line, and a carrier color signal CMN different from the carrier color signal C of the NTSC system is obtained.

This carrier color signal CMN and the luminance signal Y from the low-pass filter (18) are added in an adder (16), and a composite signal (Y+CMN) is derived at the output terminal (19).

Configuration of decoder of G2 embodiment FIG. 2 shows the configuration of a decoder according to an embodiment of the present invention.

In Fig. 2, RN is a current NTSC system TV receiver, and the output of a video detector (not shown) is Y/C.
The carrier color signal C is supplied to the separation circuit (3) and separated.
1, t) I is supplied to a color demodulation circuit (4), and the separated luminance signal is supplied to three adders (5).

Commonly supplied to (6) and (7). This adder (5
), (61 and (7) have color-1 summer tone circuit (4)
The three demodulated outputs are supplied to each adder (5).
The outputs of (7) to (7) are supplied to the picture tube (8).

(60) shows the adapter for the EDTV receiver as a whole, and the outputs of the three adders +5), (6) and (7) of the NTSC TV receiver RN are connected to the adapter (60). 3 IH delay lines (61), (62)
and (63), 3(lliI adder (64)
, (65) and (66), respectively.

Further, the output of the adder (6) of the TV receiver RN is directly supplied to the matrix circuit (71). The output of the adder (5) is connected to one fixed contact (72a) of the changeover switch (72).
), and is also supplied to the other fixed contact (72b) via the LH delay line (73), and the output of the movable contact (72c) is supplied to the matrix circuit (71). The output of the adder (7) is directly supplied to the other fixed contact (74b'') of the changeover switch (74), and is also supplied to the negative fixed contact (74a) via the IH delay!, 9! (75). ), and the output of the movable contact (74c) is supplied to the matrix circuit (71).

The output of the matrix circuit (71) and the luminance signal output of the Y/C separation circuit (3) of the TV reception mRN are connected to the subtracter (76).
), and the output of the subtracter (76) is supplied to the coefficient multiplier (
One fixed contact (79a) and the other fixed contact (79) of the changeover switch (79) are connected via (77) and (78).
b) and the movable contact (79) of the switch (79)
c) a coefficient multiplier (81) with four outputs;

(82), (83) and (84) and the high frequency conversion circuit (85).

The output of the high-frequency conversion circuit (85) is three adders (64)
.

Commonly supplied to (65) and (66). The output of the coefficient multiplier (81) is supplied to one fixed contact (86a) of the changeover switch (86), and the output of the coefficient multiplier (82) is supplied to the other fixed contact (87b) of the changeover switch (87). be done. The fixed contacts (86b) and (87a) of the switches (86) and (87) are both grounded, and the output of each movable contact (86c) and (87c) is connected to the adder (64).
) and (66). In addition, a coefficient multiplier (83
) and (84) are respectively supplied to the fixed contacts (88a) and (88b) of the changeover switch (8th), and the output of the movable contact (88c) is supplied to the adder (65). The outputs of the adders (64) to (66) are supplied to the receiver (2).

In addition, in FIG. 2, the IH delay lines (73) and (75) are provided separately to make it easier to understand the operation, but both delay lines (73) and (75) are connected to the delay lines (61) and (75), respectively. (63) can be used in common.

Compatibility with G3 NTSC system Next, compatibility between this embodiment and the NTSC system will be explained.

In the TV reception tB, Rs of the NTSC system, a composite signal (Y+CMN) similar to the output of the encoder in Fig. 1 is sent from a video detector (not shown) to a Y/C separation circuit (3
), and the carrier color signal CMN and luminance signal Y are separated.

In a color demodulation circuit (4) similar to the color demodulation circuit (34) shown in FIG. and (B-Y)a, (B-Y)b are obtained, and
From this, the following green color difference signal component (G-Y)a is obtained.

(G-Y)b is obtained.

(G-Y)a=-0,51(RY)a-0,19(B
-Y) a~ (G -Y) 0.51m YHD
” = =■a(G-Y)b=-0,51(RY)b
-0,19(B-Y)b= (G-Y) -0,19n
YHD ・”−■b and adder +51, +
61 and (7), these color difference signal components (R-
The luminance signal Y is added to Y)a to (B-Y)b to form the three primary color signal components Ra''Bb as shown in the following equations 1, 2 and 0.
is obtained and supplied to the picture tube (8).

The second terms in formulas ①, ②, and ② are expressed as N
This is a cross-color-like unnecessary component that occurs when receiving with a TV receiver using the TSC method. By appropriately selecting the value so as not to exceed 1/2 of the three primary color signal components, it is possible to suppress the value to below the permissible limit level.

Also, one set of three primary color signal components Ra and Ga.

Since Ba and the other set of three primary color signal components Rh, Gb, and Bb appear alternately for each line, there is no problem in terms of visibility.

Operation of the decoder in the G4 embodiment The operation of the decoder (adapter) in this embodiment is as follows.

NTSC TV reception v! From the ARN, the three primary color signal components shown by the formulas 0 to 0 above are directly transmitted to the switch (72
), (74) or through the IH delay line (74).
3).

(75) and is supplied to the matrix circuit (71). The switches (72) and (74) respectively synchronize with the changeover switch (51) of the encoder shown in FIG.
c) and (74c) are each one of the fixed contacts (72
a) and (74a), and in the next line Lb, contrary to the illustration, each movable contact (72c) and (74a)
c) are respectively the other fixed contacts (72b) and (7
4b), alternately switched for each line.

Note that this line synchronization changeover is performed using another changeover switch (79
), (86), (87), (88)
The same applies to

As a result, the three primary color signal components supplied to the matrix circuit (71) are in the La state where the switches (72) and (74) are connected as shown, and in the La state where the switches (72) and (74) are connected as shown.
74) is connected in the opposite way to that shown in the figure, and the following equations 0 and 0 are obtained, respectively.

Here, the subscript "l" of each signal Br, Rt and Y)+01
indicates the signal one line before. Note that the same applies to each signal described below.

The matrix circuit (71) receives three primary color signals R and G.

In order to obtain the luminance signal Y from B, the well-known calculation Y = 0.3OR + 0.59G + 0, IIB is performed, and the outputs Yt1a and Y of the matrix circuit (71) in the above-mentioned La state and Lb state are tt b becomes the following ■ and [stock] formulas, respectively.

Yvla ”0.30Rvta +〇, 59Gtta
+0.118ha” 0.3OR+ 0.590 +
O,llB 1+ 0.11n Y HDl...
・■ Yvxb =0.30Rvzb +0.59Gvxb
+0.11B7xb= 0.30R1+ 0.59G
+ 0.11B + 0.30m YHDI...
・[Phase] In the subtracter (76), this matrix circuit (71)
The luminance signal Y is subtracted from the outputs Y7ta and Yylb of the subtractor (76) in the La state and the Lb state.
The outputs 576a and 5vsb of 57sa=0.11(BIB)+0.11nYHot=
■5veb=0.30(Rx R)+0.30mYH
o1''@Each first term in both equations can be regarded as 0'' in a general video signal with vertical correlation, so the subtracter (76) separates the Y)ID multiplied signal component. Become.

A coefficient multiplier (77) is applied to the separated YHDL signal component.
and (78), multiplied by the reciprocals of the coefficients 0.11n and 0.30m of the second term of equations 0 and 0, respectively,
Y ) ID at the outputs of both faction multipliers (77) and (78)
1 signal is obtained. This Y)IDI signal is derived via a switch (79) which is switched synchronously with the switches (72) and (74), and is derived from the coefficient multipliers (52) and (53) of the encoder of FIG. If the coefficients m and n of are chosen as m : n = 0.11 : 0.30, the coefficient multipliers (77) and (78) of the decoder
are made common, and the switch (79) can be omitted.

The Y )+01 signal derived from the switch (79) is
In the high frequency conversion circuit (85), the signal is shifted and amplified to become the high frequency luminance signal YH, which is added W (64), (
65).

(66), an IH delay line (61), respectively.

(62), (63), the three primary color signal components Ra1. Cal+ Ba1 or Rbt
, Gbt, and Bbt.

Among these three primary color signal components, Ra1. Gax, Gbt and Bbx
are mixed with the downshifted high-frequency luminance signal Y no 1 at different rates. In order to cancel out this mixed component, the coefficients of the coefficient multipliers (81) and (82) are set to - of the same magnitude and opposite sign to the coefficients of the second terms of the 0 expressions and the 0 expressions.
m and -n, and the coefficients of the coefficient multipliers (83) and (84) are set to 0.51m and 0.19n, which are equal in size and have opposite signs to the coefficients of the second terms of equation 0. . The YHDL signal derived from the switch (79) is passed through each coefficient multiplier (
Switches (86) and (87) are multiplied by predetermined coefficients in 81) to (84), respectively, and are switched in synchronization with switches (72) and (74).

(88), adders (64), (65)
, (66), and are canceled out by the YHDL signal components mixed in the three primary color signal components supplied from the TV receiver RN.

As a result, the adders (64) to (66) output the three primary color signals Rs, Gl of the previous line from which unnecessary components have been removed.

B1, the high-frequency luminance signal y in front of the l line, and the receiver (
2), and a high-definition image is reproduced.

In addition, as mentioned above, m2n = 0.11: 0
．． If the relationship of 30 is established, the coefficient multipliers (83) and (84) are shared, and the switch (88) can be omitted.

H Effects of the Invention As detailed above, according to the present invention, each of the frequency-converted high-frequency luminance signals is multiplied by a predetermined coefficient and added to a pair of color signals alternately for each line. Therefore, high-frequency luminance signals can be easily separated by signal processing within the same field on the receiving side, and high-definition images can be obtained for both still images and videos while maintaining compatibility with current methods. This provides a television signal transmission system that can reproduce television signals.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an encoder of an embodiment of a television signal transmission system according to the present invention, and FIG. 2 is a block diagram showing the configuration of a decoder of an embodiment of the present invention.
Figures 3 to 6 are spectrum diagrams and diagrams for explaining the conventional television signal transmission system, and Figures 7 to 9 are examples of the conventional television signal transmission system and its main parts. FIG. (51) is a line selection switch, (52),
(53) is a coefficient multiplier, and YH is a high frequency luminance signal.

Claims (1)

[Claims] A television signal transmission system in which a high-frequency luminance signal outside a predetermined frequency band is frequency-converted and multiplexed with a luminance signal and a carrier color signal within the predetermined frequency band, A television signal transmission system characterized in that each high-frequency luminance signal is multiplied by a predetermined coefficient and added alternately for each line to each of a pair of color signals forming the carrier color signal. .