JPH0346886A - Muse/ntsc converter and chrominance subcarrier signal generating method - Google Patents

Abstract

PURPOSE:To control an oscillation circuit for a chrominance subcarrier stably by providing a PLL means with a 1st frequency dividing means which divides the frequency of the signal of a horizontal synchronizing component by (m), a 2nd frequency dividing means which divides the frequency of the output of the oscillation circuit by (n), and a phase comparing means which compares the phases of the outputs of the 1st and 2nd frequency dividing means with each other. CONSTITUTION:The phase of the chrominance subcarrier is brought under PLL control with the horizontal synchronizing signal component so that doe disturbance becomes inconspicuous in a field period (263H period). The PLL oscillation circuit 10 for chrominance subcarrier signal operation sets the (m) and (n) of the frequency dividing circuits 14 and 22 so as to correspond to a video signal of 60Hz which is cut of the standards. The oscillator 10 operates without any trouble because of the setting even if the video signal of (60Hz field frequency) which is out of the standards is inputted. Those (m) and (n) are so set that 227.227<=n/m<=227.318 and 0.509<=263Xn/m-{263Xn/m}<=0.764.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a MUSE/NTSC converter, and particularly to a color subcarrier signal generation technique for a color encoder.

(b) Conventional technology The multiple sub-Nyquist sampling encoding method (MUSE method) is a method for band-compressing high-definition video signals and transmitting them using broadcasting satellites.
yquist Sampling Encoding)
was proposed by NHK, and NHK Satellite 2nd Channel (B
It is broadcast on Channel 11).

This method uses a single channel of satellite broadcasting (bandwidth 27M).
In order to transmit a high-definition video signal at 1 MHz), this high-definition video signal is converted to a band-compressed video signal (MUSE signal, sub-sampled video signal) with a band of 8° 1 MH2 by performing sub-Nyquist sampling using a band compression encoder. It is something to do.

The MUSE method is introduced in the following documents.

(a) NHK Technical Research, Vol. 39, No. 2, 1988, No. 172, pp. 18 (76) to 53 (111), by Ninomiya, Otsuka, Izumi, and Iwadate, “ML; SE method (b)
Magazine published by Nikkei McGraw-Hill, "Nikkei Electronics, November 2, 1987, Nα433", 189-
Page 212, by Ninomiya [Transmission method of high-definition broadcasting using satellites MU S EJ] In order to view the image of this MUSE signal (see Figure 5) on the current television receiver (TV), 1125 scanning lines are required. Scan the USE signal 1
i Convert to 1525 NTSC signals M U S E
/NTSC converter is required.

As this MUSE/NTSC converter, for example, Mitsubishi Electric Corporation's prototype MUSE/N
A TSC converter rUC-2J is known.

This MUSE/NTSC converter (hereinafter referred to as converter) converts the MTJSE playback screen with an aspect ratio of 16:9 shown in Fig. 6a into a normal MTJSE playback screen with an aspect ratio of 4:3.
In order to display the image on the TV, the reproduced image on the TV must be displayed as shown in Figure 6.
``Wide mode'' and ``Zoom up mode'' shown in FIG. 6C can be selected.

In addition to the above, image modes include "zoom up mode right" and "left" as shown in Figure 6 d and e, "horizontal compression mode" as shown in Figure 6 f, and "horizontal compression mode" as shown in Figure 6 g. A "left and right end compression mode" is known (NHK Giken Monthly Report, September 1985 issue, p. 360, JP-A-62-84685 H).
O4N7100). In addition, in the "left and right edge compression mode" shown in Fig. 6g, black and white vertical lines (It, ) (lt) are superimposed on the boundary between the normal part and the compressed part to minimize the unnatural feeling of the screen. I'm trying to reduce it.

For the above mode settings, if MUSE broadcasting is performed on multiple channels in the future, the mode settings will be stored for each channel, and the stored mode will be read out automatically when a channel is selected. It is necessary to configure the settings automatically.

The converter is the above-mentioned rtJc-2] and the magazine published by Nikkan Kogyo Shimbun Co., Ltd., Vol. 31, No. 5, Volume 4.
No. 08, April 1989 issue No. 53 X-157Xf
) Izumi, WhMM rMUSE/NTSC Converter", etc., the outline of the "zoom up mode" circuit will be explained with reference to FIGS. 7 to 9.

Figure 7s7 shows a satellite broadcasting receiving system, (40) is B
It is an S antenna. (4]) is the antenna body. (
42) is a frequency conversion circuit, which converts the received signal in the 12 GHz band to the I GHz band.

(43) is a BS tuner with a converter (44). (45) is a frequency conversion circuit that converts the signal of a desired channel among the IGH band signals into a second intermediate frequency signal (2ndlF) of 402.78 MHz.

(46) is an FM demodulation circuit. (47) is an amplifier. (48) is a control circuit consisting of a channel selection microcomputer. The control circuit (48) controls the PLL control circuit (50) to receive the signal of the desired channel.

(50) is an output processing circuit for normal broadcasting (NTSC broadcasting), which performs triangular wave removal and the like. (51) is a synchronization separation circuit that separates and outputs a synchronization signal.

(44) is a converter, and when the MUSE signal is input, M
Identify the USE signal reception and send the discrimination signal to the terminal (44b)
At this time, a keyed AFC pulse (P) indicating the clamp level period of the MUSE signal is also output from the terminal (44c). The converter (44) is
A pseudo-NTSC video signal is output from the terminal (44d).

(52) is an operation switch section.

(swl) is an output changeover switch, and (sw2) is an input changeover switch section.

(55) is a normal television receiver. (56)
is a MUSE decoder, and (57) is a high-definition television receiver. (58) is a MUSE disc player.

Keyed AFC pulse (P) from MUSE decoder (56) and converter (44) and synchronous separation circuit (51)
The vertical synchronization signal is a signal for receiving a desired channel without the influence of triangular waves in satellite broadcasting, and is well known (for example, Japanese Patent Laid-Open No. 135582/1982).

FIG. 8 schematically shows the inside of a converter (44) that converts the MUSE signal of 1125 horizontal scanning lines into the NTSC signal of 525 horizontal scanning lines. (59) on the left side of the figure is a MUSE signal processing system, which basically performs various timing controls using the synchronization signal and clock signal from the clock synchronization reproducing circuit (91). (60) is NTSC
It is a signal processing system, and is basically a tarokk synchronization creation circuit (
Various timing controls are performed by the synchronization signal and clock signal from 93).

In FIG. 8, (61) is a low-pass filter of s, tM) (z. (62) is a clamp circuit that performs a clamping operation during the horizontal synchronization period. (63) is a 16.2M
This is an A/D conversion circuit that operates based on the H1 sampling clock.

(64) is a time axis expansion circuit, which expands the time axis of the central 1050 video signals of the 1125 scanning lines of the MUSE signal into an NTSC signal. (65) is MUSE
This is a signal IH delay circuit. (66) and (67) are memories for time axis expansion of the Y signal, Memo J (66) is for even lines, and memory (67) is for odd lines.

(68) is a vertical filter circuit for luminance signals, (6
9) is an IH delay circuit, and (70) is a vertical filter square calculation circuit.

(71) is a vertical filter circuit for the RY signal. (
72) is a shift register for the time axis expansion circuit.

(73) is an IH [shift register for extension circuit, (74>
is a vertical filter arithmetic circuit.

(75) is a vertical filter circuit for the B-Y signal, (
76) is a time axis expansion circuit, (77) and (78) are LH delay circuits, and (79) is a vertical filter arithmetic circuit.

(80) is a D/A conversion circuit for Y signal, (81) is R-Y
Signal D/A conversion circuit, (82) is B-Y signal D/A
It is a circuit of change. (83) is a low-pass filter for the Y signal, (84) and (85) are low-pass filters for the RY and B-Y color difference signals, and (86) is a matrix circuit.

(87) is an NTSC color encoder. (88)
is a color modulation circuit, and (89) is a color subcarrier oscillation circuit, which oscillates at 3579545 Hz. (90) is an adder circuit.

(91) is a clock synchronized regeneration circuit, and the input MUSE
A 16.2MH1 clock signal, frame pulse, and horizontal synchronization signal synchronized with the clock component of the signal are reproduced.

Further, this clock synchronization reproducing circuit (91) determines whether or not it is the MUSE signal time based on the presence or absence of synchronization, and outputs a determination signal. Also, the keyed AF corresponding to the clamp level period
A C pulse (P) is also output.

(92) is a control timing signal generation circuit that generates various signals for controlling the circuits (65), (66), and (67) based on the signals from the tarlock synchronization reproducing circuit (91).

(93) is a clock synchronization generation circuit that generates horizontal synchronization and clock signals for NTSC. This circuit (93)
The 10.08 MHz reference signal is PL synchronized with the 16.2 MHz clock signal for MUSE.
L controlled. (94) is 1/4. Frequency dividing circuit, (9
5) is a 1/I frequency divider circuit, (96) is a phase comparator, (97
) is a low-pass filter, (98) is No, 08MH
, is the reference oscillator circuit for . (99) is 18 for creating a horizontal synchronization signal. It is a frequency dividing circuit. The 17.4° frequency dividing circuit (99) is reset by the frame synchronization signal of the 30 Hz MUSE signal from the clock synchronization reproducing circuit (91).

(100) is a frame synchronization signal from a clock synchronization generation circuit (93), a horizontal synchronization signal, and a clock signal of 10.08MH to the circuits (66) (67) (69) (72).
This is a control timing signal generation circuit that generates various signals for controlling (73), (76), (77), and (78). This circuit (100) also generates a vertical synchronization signal from a horizontal synchronization signal and a frame signal, and generates a composite synchronization signal (SYN
C) is output.

The processing of the above video signal will be briefly explained.

The input MUSE signal is passed through a low pass filter (61)
, a clamp circuit (62), and an A/D conversion circuit (63), and are input to a time axis expansion circuit (64). The MUSE signal input to this time axis expansion circuit (64) (Fig. 9a)
) is IFIJ! ! The delay circuit (65) carries out an IH delay.

This output is shown in FIG. 9C.

Writing to the memory (67) is controlled by the control timing signal generation circuit (92) described above, and only the central portion of the Y signal of the even line and the color signal (R-Y signal) of the odd line is written (9th (see Figure C), and this memory (67) is controlled like a FIFO memory.
00) to output the signal shown in FIG. 9d. Among these signals, the time expansion of the color signal is insufficient, but the time axis of the Y signal is expanded to the normal value of the NTSC signal.

Furthermore, the memory (66) is similarly controlled to perform time axis expansion as shown in FIG. 9ab.

The two Y signals shown in FIG. 9bd are input to a Y signal vertical filter circuit (68), subjected to vertical filter processing, and output as Y signals.

In addition, the RY signal and BY signal in FIG. 9 bd are R-Y, respectively.
After being inputted to the signal vertical filter circuit (71) and the B-Y signal vertical filter circuit (75) and subjected to time axis expansion, vertical filter processing is performed and the R-Y signal, B- It is output as a Y signal.

These Y, R-Y, and B-Y signals are processed by the D/A conversion circuit (
80) (81) (82), low pass filter circuit (83
) (84) (85), the color encoder circuit (
87) and the color television video signal (
NTSC signal).

The oscillation circuit (89) of this color encoder (87) is
Contrary to common sense, do not perform PLL control. I will explain the reason.

As is well known, the regular -NTSC signal satisfies the following conditional expression.

f Ie is the color subcarrier frequency.

f is the horizontal synchronization frequency.

However, this is the case for color broadcasting with a field frequency of 59.94 Hz and a horizontal synchronization frequency of 15.734266 KHz.

As mentioned above, the field frequency of the ML'SE signal is 6
It is 0Hz. The video signal of the converter created by converting this MUSE signal is also 60 Hz. Therefore, the horizontal frequency is also 15.75K Hz, which is the same as the black and white broadcasting standard.
becomes. In other words, the converter that converted the MUSE signal (
The output video signal of 44) is the same as the black and white broadcasting standard, and the value ratio with the color broadcasting standard is also 1000:10.
It becomes 01.

Therefore, the above equation (1) does not hold true.

Therefore, the color subcarrier oscillation circuit (
87) self-oscillates without synchronizing with the horizontal frequency and outputs a signal of about 3.579545 MHz.

In addition, the color subcarrier oscillation circuit (
If the frequency of 89) is forcibly controlled, the frequency of the color subcarrier will change by as much as 0.1% from the normal value, and the color synchronization circuit of a normal television receiver will not operate normally.

The oscillation frequency of this color subcarrier oscillation circuit (89) and M
Horizontal frequency (fh) of video signal created from USE signal
The relationship is as follows.

tL, hard to stand out.

However, as described above, since the NTSC encoder color subcarrier oscillation circuit (89) self-oscillates, a frequency shift occurs. For example, as shown in FIG. 12, the phase of the color subcarrier is 1 field (2, that is, the color
As shown in Figure 0, the output of the converter is
When viewed on a black-and-white television, this color subcarrier becomes a dot pattern as shown in Figure 11, and its phase (brightness and darkness) is approximately reversed for each field (every 263 horizontal scans), so the spatiotemporal integration of the eye Due to the effect, a diagonal pattern appears due to the lack of clarity.

(c) Problem to be solved by the invention In order to prevent this problem, the color subcarrier oscillation circuit (89
), it is sufficient to use a highly accurate and highly stable one that does not cause frequency deviation.

However, such an oscillation circuit is expensive and cannot be used in consumer equipment.

(d) Means for Solving the Problems The present invention has 1125 horizontal scanning lines and a field frequency of 6.
0Hz MUSE signal, 525 horizontal scanning lines,
In the MUSE/NTSC converter (44) that converts into a pseudo NTSC signal with a field frequency of 60 Hz, oscillation circuits (20) (20a) (20a') are used to create a color subcarrier signal for creating the pseudo NTSC signal. ) is controlled in phase synchronization with the signal of the horizontal synchronization component.
0), this PLL means (10) includes first frequency dividing means (14) (14) for frequency-dividing the horizontal synchronization component signal by m, and second frequency dividing means (14) for frequency-dividing the output of the oscillation circuit by n. The frequency dividing means (22) (22゛) and the phase comparing means (16) for comparing the phases of the outputs of the first and second frequency dividing means, and the output of the phase comparing means (16) are inputted and the oscillating circuit is operated. It consists of a low-pass filter (18) to control, and is characterized in that m and n (n and m are natural numbers) satisfy the following two formulas.

The horizontal synchronization component signal is a horizontal synchronization signal.

The present invention is characterized in that the output of the oscillation circuits (20a) (20a'') is frequency-divided to create the color subcarrier signal.

The present invention also provides a color subcarrier signal creation method for creating a color subcarrier signal that is phase-synchronized with a horizontal synchronization component of a luminance signal. The color subcarrier signal is phase-controlled by the horizontal synchronization component in 263 horizontal scanning periods with respect to the phase shift X in one horizontal scanning period.

(E) Effect In the present invention, the phase of the color subcarrier signal with respect to the horizontal synchronization component is set such that the phase of the color subcarrier signal with respect to the horizontal synchronization component is set such that dot interference becomes less noticeable during the field period (263) one period).
Controlled by horizontal synchronization signal component.

(f) Example An embodiment of the present invention will be described with reference to FIG.

(10) is a PLL oscillation circuit for creating a color subcarrier signal, and the circuit configuration itself is well known. (12
) is an input terminal for a 15.75 KHz NTSC horizontal synchronization signal. (14) is a divide-by-18 circuit.

(16) is a phase comparator circuit. (18) is a low-pass filter. (20) is a voltage-controlled oscillation circuit for creating color subcarriers. (22) is a 08 frequency divider circuit.

The feature of this circuit is that m and n of the frequency dividing circuits (14) and (22) are set in order to cope with a video signal of 60 Hz, which is out of the standard. With this setting, the oscillation circuit (10) operates without any problem even if a non-standard video signal (with a field frequency of 60 Hz) is input.

The selection of n] and n will be described below.

First, the frequency f@e' of this color subcarrier signal must be within the synchronization range of the color subcarrier signal of the television receiver. In other words, this frequency f sco is a variation value within ±0.02% from the normal frequency f-.

(1-0,0002)-f, c≦f +c′≦(1+
O, 0O02)-f sc... (3) In order to prevent don't interference between fields, there is also a phase difference of ), so assuming that there is a phase difference between fields, it is as follows.

...... (4a) ...... (4b) In addition, T□jH is the time required for 263 horizontal scans, and [f,,'・TtssH] is fat"Tx
This is the integer part above the decimal point of s and l.

Furthermore, since the color subcarrier signal is subjected to PLL control, it is as follows.

f, c'=15750

227, 227≦°8≦227.318
...(6) 0, 509≦263X'8-f263X
"/,]≦0.746... (7) n and m are natural numbers, [263X"/. ] is the value of the integer part of (263X”/,).

m and n that satisfy equations (6) and (7) above are, for example, m=
4, n=909, and at this time, 18=227.25.263X"8-[263X"/. ]-0.75.

Another example is m=11, n += 2500, and at this time, 'to -227,273,263X'
to (263xa/, ]-0,727.

The dot pattern is as shown in FIG. 2 when m=4 and n=909. Also, m=11. When n=2500, the result is as shown in FIG.

In this manner, in this embodiment, the phase of the oscillation circuit (20) is controlled by the horizontal synchronizing signal, thereby making it possible to prevent dot interference between fields.

The circuit configuration of the oscillation circuit (20) is as shown in FIG.
) and an ll1 frequency divider circuit (20b) that divides the frequency by two.

Furthermore, in a configuration in which the frequency of the flat-nod synchronization signal and color subcarrier signal is directly divided, the values of m and n cannot actually be set very large so that phase control can be performed quickly. For this reason,
As shown in FIG. 4, the output of the oscillation circuit and a frequency four times that of the horizontal synchronizing signal component may be compared. In Fig. 4, (99a) is a 1/16° frequency dividing circuit, (99b)
is a divide-by-18 circuit, (14') is a divide-by-183 circuit, (22
°) is 18. . Frequency divider circuit, (20a') is approximately 14
．． Voltage controlled oscillator circuit that oscillates at 32MHz, (20
b') is a divide-by-18 circuit.

Note that in the above color encoder, Y, B-Y, and R-Y signals are input, but if an inverse matrix circuit is provided,
R, GB multiplied signals may also be input.

In this embodiment, phase control is performed to eliminate dot interference between fields, but this may be reduced by inverting the phase of the color subcarrier between frames.

Further, when the pseudo NTSC signal of this embodiment is subjected to RF conversion, the audio carrier frequency may be in a frequency interleaving relationship with the color subcarrier frequency.

(g) Effects of the invention As described above, according to the present invention, M US E / N
Dot interference can be reduced in the TSC converter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing one embodiment of the present invention. FIG. 2 is a diagram for explaining the effect. FIG. 3 is a diagram showing another example of the present invention. FIG. 4 is a diagram showing still another example of the present invention. Fig. 5 shows the PwI US E signal, Fig. 6, Fig. 7, Fig. 8, and Fig. 9 show the M U S E/'N T S
Diagrams for explaining the C converter, Figures 10 and 11
12A and 12B are diagrams for explaining a dot pattern based on a color subcarrier signal. (44)...=MUSE/NTSC converter, (20)...approximately 3°58MH2 oscillation circuit, (20
a)...Approx. 3.58M H! An oscillation circuit that oscillates at an integer multiple of (20a') -...about 14.32? v1)1. oscillation circuit, (10)... oscillation circuit for color sub-transport (PL
L means). (14)...1-8 frequency dividing circuit (first frequency dividing means), (14
)...1/71 frequency dividing circuit (first frequency dividing means), (22
)...18 frequency dividing circuit (second frequency dividing means), (22°)
...18. . Frequency dividing circuit (second frequency dividing means). (16)...Phase comparison circuit (phase comparison means), (18
)...Low pass filter.

Claims (1)

[Claims] (1) 1125 horizontal scanning lines, field frequency 60H
MUSE that converts the MUSE signal of Z to a pseudo NTSC signal with 525 horizontal scanning lines and a field frequency of 60Hz.
/NTSC converter (44), the oscillation circuits (20) (20a) (20a') for creating color subcarrier signals for creating the pseudo NTSC signal are controlled in phase synchronization with the horizontal synchronization component signal. PLL means (1
0), this PLL means (10) includes first frequency dividing means (14) (14) for frequency-dividing the horizontal synchronization component signal by m, and second frequency dividing means (14) for frequency-dividing the output of the oscillation circuit by n. Surrounding means (22) (22'
), a phase comparison means (16) for comparing the phases of the outputs of the first and second frequency dividing means, and a low-pass filter (18) to which the output of the phase comparison means (16) is input and controls the oscillation circuit. The above m and n (n and m are natural numbers) are
The following two equations 227.227≦n/m≦227.318 0.509≦263Xa/m-{263Xa/m}≦0
．． MUSE/NTS characterized by satisfying 764
C converter. (2) The MUSE/NTSC converter according to claim 1, wherein the horizontal synchronization component signal is a horizontal synchronization signal. (3) The output of the oscillation circuit (20a) (20a') is
The MUSE/NTSC converter according to claim 1, wherein the color subcarrier signal is created by frequency division. (4) In a color subcarrier signal creation method for creating a color subcarrier signal phase-synchronized with a horizontal synchronization component of a luminance signal, a phase shift X of the color subcarrier signal with respect to the horizontal synchronization component in 263 horizontal scanning periods. The color subcarrier signal generation is characterized in that the phase of the color subcarrier signal is controlled by the horizontal synchronization component so that, with respect to the phase shift Y of one horizontal scanning period, the color subcarrier signal is approximately X=0.5+Y/2. Method. (5) The color subcarrier signal generation method according to claim 4, wherein the phase shift X is an 8/11 cycle, and the phase shift Y is a 3/11 cycle.