JPS60130294A - Sampling method of color television signal - Google Patents

Abstract

PURPOSE:To realize a sampling method of less color blurring and less quantity of transmission codes by sampling color television signals with pulses which have certain phase relations to a vertical synchronizing signal, a horizontal synchronizing signal, and a subcarrier signal and have a specific frequency. CONSTITUTION:Color television signals on a line 101A are sent to not only a subcarrier generating circuit 201 but also a horizontal synchronizing signal generating circuit 202 and a vertical synchronizing signal generating circuit 203 to generate a subcarrier fSC and horizontal and vertical synchronizing signals. The subcarrier fSC is converted to pulses by a pulse generating circuit 204 and is applied to a quadrupling circuit 205 and has the frequency multiplied to become pulses having a frequency 4fSC. Outputs of circuits 202-204 are supplied to a vertical synchronizing reset pulse generating circuit 212, and a reset pulse is obtained which is outputted when three input pulses coincide with one another. A frequency dividing circuit 206, a 1/2 frequency dividing circuit 210, and a 1/(525) frequency dividing circuit 211 are reset on a basis of this reset pulse to obtain sampling pulses which have certain phase relations to three input pulses.

Description

[Detailed Description of the Invention] frl]-〇Icheon Field Honmenmei frl1, Digital Transmission of Color Images, Accumulation/1. This article concerns a color television signal sampling method that can be used in various fields such as narrow 1i1 area transmission and still image transmission (Ruru 1, Conventional configuration and its problems) However, when selecting the sampling frequency fs for encoding a color television signal, the color signal subcarrier frequency (subcarrier) f8 is usually used.
A frequency three or four times o is used. f6〉2f5
o, and there are cases where a value close to 2fBc is used3.The sampling theorem (Nyquist's theorem) states that when the highest frequency of the sampled beam is Wll, the sampling interval T is 1
/2 W seconds or less, and conventionally, this condition has been observed and the original signal has been reproduced based on the sampled signal. In addition to the video signal in which the carrier color signal is superimposed on the tck and luminance signal in the conventional method,
;11 signal.

It was necessary to sample the television signal, including the pedestal level, at the sampling frequency described above.

Therefore, when transmitting or storing a color television signal, the amount of information in the color television signal inevitably increases. To provide a color television signal sampling method that transmits or stores color television signals with a small amount of code, has little gray shift, is reproducible, and can have a wide range.

Structure of the Invention The present invention samples a color television signal with a pulse having a frequency that is in a predetermined phase relationship with a vertical synchronization signal, a horizontal synchronization signal, and a subcarrier signal and whose frequency is an integer fraction of twice the subcarrier signal frequency. , by restoring the sampled information into a pulse whose phase relationship and frequency with the vertical sync signal, the horizontal sync signal, and the subcarrier signal are in the same relationship with the sampled pulse, This aims to achieve the above objectives.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below.1 The basics of this embodiment are that the sampling device receives a color television signal, a vertical synchronization signal, and a horizontal synchronization signal.

Subcarrier signal (The subcarrier signal is the color television image part (
A frequency that does not exist in the subcarrier frequency and has a fixed phase relationship with the color burst signal is sampled with a sampling pulse of an integer fraction of twice the subcarrier frequency, The sampled information is transmitted to the vertical synchronization signal, horizontal synchronization signal,
A color television signal is restored using a pulse having the same phase relationship and frequency with the subcarrier signal as the sampling pulse.

In this example, a color television signal is processed at a sampling frequency of 18
Sample it with . fs is f6=2f6o/n-(1). Although the practical value of n is 1 or 2, it is not necessary to limit it to this only.

The sampling point for color television signals is the vertical synchronization signal.

The horizontal synchronization signal has a predetermined relationship with the phase of the subcarrier signal for the electric signal. Since the signal restoring device knows in advance the predetermined relationship between

In this embodiment, the color television signal is E--EY 1-ARrOSC2π ・-fSc ・t
) 卜AB :;in(2π ・, f5o , t )
・ ・(2) One scanning line is sin (2yr ・
fso-t) = o, l: What is sampled when "t,
lli L, pulse to R type sampling pulse or R type reading 1i i, pulse and ill. Another scan line is co
s(2π'sc t>0 lI, 'l'&i).The scanning line in this case is the BJ helicopter scanning line and 11 P, and the pulse at this time is the B visual sampling pulse t ta i "l
: For B type reading, called pulse h2ru1゜This example PC
:t, - The arrangement of the R-type and B-type scanning lines with 71 units was advantageous for the sampling of color television signals. There is a police box for each line. Other arrangements are B, B, R, R, B, B.

The relationship between each sample point within one field and the vertical synchronization signal and horizontal synchronization signal 9 electric signal subcarriers is determined as a strict relationship.

Therefore, there is no need to sample and transmit these vertical synchronization signals, horizontal synchronization signals, burst signals, etc. from the sampling device to the restoration device. The restoration device can use these signals generated within the device from the white to reproduce the color signal.

Now, the information to be transmitted or stored (dl) is only the range of the useful image. What the reproduction device has to know is the position of each sampled signal.

For this purpose, it is sufficient for the playback device to know what the sign of the first sample point is1. Note that one of the other pieces of information that the playback device must know is:
Since there are four combinations of the phases of the vertical synchronization signal, horizontal synchronization signal, and one-color carrier signal, the current field is which of the four.

The code transmission method uses one field of code as one information transmission frame, and adds a 2-bit code indicating which of the above four combinations it corresponds to to the first CjQ part of the information.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to drawings of a system used in a color television signal sampling method according to an embodiment of the present invention. For the sake of brevity, the NTSC system is the standard for color televisions.
Although the arrangement of the R-type and B-type scanning lines iri and alternation of each line will be described as an example, the present invention is not limited to these.

FIG. 1 is a diagram of a system in which the present invention is applied to a digital band compression color television transmission and reproduction device 4. As shown in FIG. An NTSC signal is output on line 101A, and this signal is transmitted to sampling timing generation circuit 102 and sampling circuit 1○.
The signal sampled by the sampling circuit 103 is sent to the quantization circuit 104 and is converted to (1'
] Stored in memory circuit 1○6. Encoding circuit 106
reads the data stored in the memory circuit 1*5 as necessary, performs compression processing, and forms a code for transmission. This code is sent via modem 107 to line 1*7A.

On the other hand, modem 108 on the receiving side sends the received code sent from modem 107 to decoding circuit 1*9. This decoding circuit 109 expands and restores the received code, and stores it in the memory circuit 111 as data having the same contents and functions as the memory circuit 106 . Then, the color television signal restoration circuit 112 reads necessary data from the memory circuit 111 according to the timing signal generated by the read timing generation circuit 110, and restores the color television signal. The digital-to-analog conversion circuit 113 converts the output signal sent from the color television signal restoration circuit 12 from a digital signal to an analog signal, adds a pedestal level, vertical and horizontal synchronization signals, and a burst signal, and converts the output signal into an NTS
A T signal is sent to the color television display device 114. .

A more specific configuration of the above configuration and its operation will be described below with reference to the drawings.

FIG. 2 shows the sampling timing generation circuit 1 shown in FIG.
02 is shown.

The color television signal on line 101A-1- is sent to subcarrier generation circuit 201, and f = 3.6 + 95454 subcarriers are generated by subcarrier generation circuit 201.

Further, the color television signal is generated by the horizontal synchronization signal generation circuit 202.
, is also sent 113 to the vertical synchronization signal generation circuit 203, and generates a horizontal synchronization signal and a vertical synchronization signal.

Now, the subcarrier output from the subcarrier generation circuit 2○1 is input to the Zab gear rear pulse generation circuit 2○4, and 31
A thin pulse with a frequency fsc that rises at time t that satisfies n(π·fsC-1)-0 is generated on the line 204A1-. This subcarrier pulse is multiplied into a pulse with a frequency of 4 fsc by a quadrupling circuit 205 using a PLL or the like. (The frequency will be multiplied and divided from now on, but the pulse of frequency fsc\"l'+S111,'-fSC
It is assumed that the phases of the pulses before and after the multiplication/frequency division match, so that the rising edge of one out of four pulses of The frequency of one out of two of these pulses matches the phase of the Zab gear rear pulse mentioned above, and as an R-type sampling pulse, it is divided into 1/2 by the line 20.
An R-type sampling pulse is generated at 7AJ:.

This R-type sampling is sin (2π・fSC・t
)=o. The output of the frequency dividing circuit 206 is then sent to the B-type summing pulse generation circuit 208, which generates a line 2.
Generate a B-type sampling pulse on 08A. This B
Type sampling pulse ij, rns (2π・fsc')
=o is leaked, or 1) rises at the midpoint of the pulse of line 2○7A-1-.On the other hand, the output of the 4 multiplier circuit 205 is the 1/455 frequency divider circuit 2.
09, and the frequency fh of the horizontal synchronizing pulse is 2
The pulse of 31.468s3o9Jl17 is 17
It is generated by the 455 frequency divider circuit 209. and 174
55 Frequency divider circuit 2○9 output jl, 1/2 Frequency divider circuit 2
1○, frequency fh-1cs, 73426s
A 73 kHz horizontal sync pulse is created and sent on line 210A. 1/2 The output of the frequency divider circuit 209 is 5.17
625 frequency divider circuit 211, and frequency f-59, 940059+1 is sent by this 11525 frequency divider circuit 211.
7 (7) m Direct F1M pulse signal is generated on M 21 IA.

Now, the output from the horizontal synchronization signal generation circuit 2O2, the output from the vertical synchronization signal generation circuit 2O3, and the output from the subcarrier pulse generation circuit 2O4 are sent to the vertical synchronization reset pulse generation circuit 212. The reset pulse generation circuit 212 generates a vertical synchronization reset pulse on line 2.
1- generated on 12A, this pulse (bow 1, horizontal synchronization signal, vertical synchronization (1'i "'9, sub gear rear pulse) is almost in phase. The pulse coincides with the rising edge of the sub gear rear pulse.

Then, the vertical synchronization reset pulse d1 from the reset pulse generation circuit 212, each frequency dividing circuit 206, 210, 211
sent to. Therefore, the rise of the vertical synchronization reset 7t pulse almost coincides with that of the vertical synchronization pulse, the horizontal synchronization pulse, and the R-type sampling pulse.

The OR circuit 213 receives the R-type sampling pulse on the line 207A, the horizontal synchronizing pulse on the line 21○Al-,
When the vertical synchronizing pulse of line 211A”- matches,
A pulse that coincides with these is output, and the rising edge of this pulse is 1, which is also the origin 1=0 of time t described in 2. This pulse occurs once every four fields. This is also the origin of synchronization in case (a) shown in FIG. 4, which will be described later.

Next, the phase of each pulse signal will be explained with reference to the drawings.

FIG. 3 is a waveform diagram showing the phase relationship of each pulse. 2 indicates the pulse position on the horizontal scanning line consisting of each signal 1id1, and the time is 16 from the left to the right in the figure.In this embodiment, the pulse time: is defined and explained by the time at which the pulse rises, but
Of course, it is not limited to the falling time of the pulse, and may also be the falling time of the pulse.
1-) is the vertical synchronization signal of line 212A-1- in FIG.
It is output when the subcarrier pulse and subcarrier pulse almost match. If the starting point of horizontal scanning, gland I-, is time 3○1, then the subcarrier (, r;
The pulse 311A (to FIG. 3) which shows no amplitude O and is generated at the first time when it crosses the line 3○1C is 1 which coincides with the time line 3○1, that is, in FIG.
・301 B (Fig. 3 C) There is a subcarrier signal, and the line 1 and the phase are shifted by 180 degrees. ○
1A (Fig. 3 H) is the line 3○1C (3rd [
A pulse of 30
4B (Fig. 3), the subcarrier 301B (Fig. 3, H) exhibits an amplitude O, and the line 301C (Fig. 3, H) goes from negative to negative. Pulse 307A (Figure 3...
) occurs at the time when the subcarrier 3○18sun θ゛1.301 B (Fig. 3 H) crosses the line 301C (Fig. 3 H) indicating the amplitude O, and is connected to the R-shaped sample points.・Pulse 308A
(Fig. 3 D) is the subcarrier 3○1A-4 (d301
Occurs at the time when the absolute value of B (Figure 3 H) is maximum, and B
It becomes a sample point of the type. Pulse 3O4A and Pulse 3○4B
(Fig. 3 I port) and 1", horizontal synchronizing pulse 31○A (
If we look at Fig. 3 (e) as a basic thread, the phase of the signal is shifted by 180 degrees from the horizontal scanning line tσ. 4. NTSC system. -te f
(Jl, horizontal synchronizing pulse 31○A (Fig. 3 E) is replaced by sub gear rear pulse 304A or 3○4B (Fig. 3 I).

occurs every 262.5 times. Vertical sync pulse 31
1A (to Figure 3) is 227 of the horizontal sync pulse 310A (E to Figure 3), which is generated every 5 times. (525 horizontal sync pulse) to coincides with the horizontal sync pulse 310A (Fig. 3 E), and 1 field (26
2, 6 horizontal synchronization pulse) It repeats firing at the middle position of the horizontal synchronization pulse coincident with fi7. Line 302 indicates the starting point of the effective screen at time 1-1, and the image is sampled and processed at the Zanopling nose between time 302 and time 301.

Between time 301 and time 302 (d1, which is the horizontal retrace time), each pulse signal shown in FIG. ing.

Next, sampling points will be explained in units of fields.

Fig. 4 explains the relationship between the vertical synchronizing pulse 31゛1A, the horizontal synchronizing pulse 310A, the subcarriers 3○1A and 3○1B, and the depth/honization point in units of fields (J-Z).
It's a meme thing. The time is shown in Figure 4 (a) → (
b) The process progresses as follows: -> (c) → (d) → (a).

In FIG. 4(a), the outer frame 4○1 includes one frame l,
1 showing the whole, in relation to this outer frame 401, arrow 4○4 il, position of 4 direct phase pulse 311A, arrow 1-
Jl 4071dH water' = lZ - synchronization pulse 31○A position, range 405i1, east [rf retrace time, range 4O are the times when scanning lines for sampling and transmitting images exist, range 408U1, water r retrace The time range 4*9 indicates the time for sampling and transmitting the image on the scanning line. 1) The line 402 indicates a scanning line (the number of lines is not correctly displayed in the figure), and the waveform line 403 indicates a subcarrier. The first black circle 41o indicates the point where the image is sampled using the R-type sampling pulse, and the x mark 411 indicates the point where the image is sampled using the B-type sampling pulse. 40
Displays and explanations regarding 1 to 411 are shown in Figure 4■), (
c) and (d) are omitted, but Figure 4 (a)
1° Now, as shown in FIG.
0, where the phases of the subcarrier pulses 304A match,
In Figure 4(1)), the vertical sync pulse is in the middle of the horizontal sync pulse. Furthermore, in FIG. 4(c), the vertical direction JtJ] Hals is in the middle of the subcarrier pulse compared to FIG. 4(a), and in FIG. 4(d) it is still vertically the same.
In the υ1 pulse, the phase of the subcarrier pulse with respect to the vertical synchronization pulse is shifted by 1 Bo degree compared to that in FIG. 4 (1)).

As mentioned above, when considering the vertical synchronization pulse as the center, there are four types of combinations of phase relationships between the horizontal synchronization pulse and the sub-gear rear pulse.
, (b) , IC> , (d) 33 Examples (In this example, vertical synchronizing pulse, 74 R-type and B-type sampling pulses per horizontal pulse) A relationship is defined between the transmitting device and the reproducing device, and the receiving and reproducing device samples the received frame in the fourth [21] order according to a rule.
If you know which of the four types it is, and whether it is the first sample value in one frame, you can determine the vertical direction, horizontal synchronization signal, and burst signal. It is possible to know whether the received image value is R type or B type, and what position in the frame it is, without any other information.
Color television broadcasting (if raw 1) Next, regarding the transmission code -y3 related to one video frame (or field), we will explain [110-
1, as shown in Figure 5, one transmission frame 50○
d1, Pro for identifying the beginning, 501, Fig. 4 (
It consists of a code block 602 consisting of 2 bits that identifies which state is in a) to (d), a first ljL forest line omitted from a plurality of lines, -503, and a final scanning line code 504. There is.

The read timing generation circuit 11○ and the color television signal restoration circuit 112 shown in FIG. 1 will be explained in detail below.

FIG. 6 is a diagram showing the detailed configuration of the timing generation circuit 110 shown in FIG. The 1/2 frequency divider circuit 6○2 inputs the pulse signal output by the pulse oscillation circuit 601, divides the frequency by 1/2, and outputs 7 pulses on the line 603A with an R type reading of 7.1590908N. 1 generated, a delay that delays the balun output by this frequency dividing 1iIi path 602 by half a cycle] L circuit 604
1d, line 604 A (a CB type T/L output pulse is generated).

On the other hand, 1/
455 frequency division 1 7455 frequency division 1 Iro 605
The output of is further divided by the 1/2 frequency divider circuit 606,
A horizontal sync pulse of 15,73426549kll+ is generated on line 606A. 1/455 frequency dividing circuit etc.
7 generates a 59.94○○59Hz vertical sync pulse on line 607A. And an AND circuit 6 that takes the AND of the B-type reading pulse, horizontal sync pulse, and vertical sync pulse.
08, when the rising phases of these pulses match,
A match pulse is generated on line 608A. The sampling pulse on line 603A is frequency divided by 1/2 and the data is 5.
A pulse output circuit 609 that outputs a 0% pulse divides the frequency and shapes the pulse into a pulse with equal periods of high and low levels, and further, a delay circuit 610 outputs a subcarrier period of 1/f.
A sinusoidal subcarrier is output onto a line 611A by a filter 611 which is delayed by a time of 1/4 of s0 and further attenuates more than 4) lh. Note that line 603 in Figure 6
A, 604A, 606A.

The signals on 607A and 6○8A are respectively line 2 in Figure 2.
07A, 208A, 21OA, 211A.

It almost corresponds to the signal on 213A.

Next, a color signal restoration circuit, which is a main part of the color television signal restoration circuit 112 shown in FIG. 1, will be explained using FIG. 7, and relationships such as timing will be explained using FIG. 8. Note that the method of providing the synchronization signal and the burst signal will be omitted.

In FIG. 17, the terminal 701 receives the signal 8○2 in FIG. 8 read out from the memory circuit 111 of the scanning line currently being reproduced at timing 801 in FIG. 8, and the terminal 7○4 receives the signal 8○2 of the current scanning line. The signal of the previous (or subsequent) scanning line is read out at timing 803 in FIG. 8, and a signal 804 in FIG. 8 is applied. The delay circuit 7*5 in FIG. 7, which delays the signal by one sampling period (1/2 f8°), outputs a delayed signal to the line 705A. The output of subtraction circuit 706, which subtracts the signal input to terminal 704 from the signal on line 705A, reduces the output to 1.
It is input to an amplitude 1/2 circuit 707 which attenuates the signal to /2.

Then, the latch circuit 70B receives the eighth signal inputted to the terminal 703.
The readout pulse 803 in the figure (pulse output after the signal from the amplitude 1/2 circuit becomes stable) latches the output from the amplitude 1/2 circuit 7○7 and inputs it to the terminal 7○2. It is cleared (the contents are set to 0) by the present/in read pulse shown in signal 8○1 in the figure. The adder circuit 709 is a circuit that adds the output from the latch circuit 7*8 and the current line signal 8*2 input to the terminal 701, and outputs the addition result onto the line 709A. As a result of this addition, if the current line is R type, the time between pulse 8○1 and pulse 8○3 is the sum of the luminance signal and the red color difference signal, and the time between pulse 803 and pulse 801 is the sum of the luminance signal and the red color difference signal. is the sum of the color difference signals of pulse 801 and pulse 803 if the current line is type B.
The time between is the sum of the luminance signal and blue color difference signal, pulse 8
The time between ○3 and pulse 8o1 is the sum of the luminance signal and the red color difference signal. Therefore, the signal on line 7○9A is 4W
By passing the above through a filter 710 that attenuates the line 7
The color television signal shown in equation (2) can be reproduced on 1○A.

The subcarrier signal for the signal on the line 71○A''2 is an R-type reading pulse, which is frequency-divided by 1/2 and output from a pulse output circuit 609 that generates a pulse related to duty 5○, as a readout pulse 801 or Delay by 1/4 of the interval of 804.

A delay operation for this purpose is performed by a delay circuit 610 shown in FIG. 6, and a delayed output is output on line 61oA.

From this, by passing it through a filter circuit 611 that extracts the sine wave of the fundamental frequency of the subcarrier signal, the subcarrier for the color television signal on line 710A is obtained on line 611A.

As described above, the color television signal is reproduced. By adding a synchronization signal, a burst signal, and a pedestal level to this signal, an NTSC color signal can be obtained.

Details of the invention As explained, the present invention uses a vertical synchronization signal.

Horizontal synchronization signal, the color television signal is fully sampled with pulses whose frequency is in a predetermined phase relationship with the subcarrier signal and is an integer fraction of twice the subcarrier signal frequency, and the vertical synchronization signal and horizontal synchronization signal are By restoring the sampled information using a pulse whose phase relationship and frequency with the subcarrier signal are the same as those of the sampling pulse, transmission or storage can be performed with a small amount of code, and It has less color shift, and can be reproduced with a large dynamic range, making it possible to reproduce accurate color television images even when sampling at a sampling frequency of an integer fraction of 2f, which is coarser than before. , the effect is great.

[Brief explanation of drawings]

FIG. 1 shows a color television set according to an embodiment of the present invention.
A block wiring diagram of the digital transmission system for color television images used in the sampling method of 5-"J. Figure 2 is a block wiring diagram of the sampling circuit, which is the main part of the digital transmission 7 stems, and Figure 3 is the sample. /i-1V')
1 pulse waveform diagram, Figure 4 shows the vertical sync pulse, horizontal sync pulse, sampling pulse, sampling range and conceptual diagram of the engineering waste, Figure 5 shows the 1-screen TV picture (/(,), J, C E
, 1. Conceptual diagram of the transmission frame to be transmitted, Figure 6 Q'L Block connection 1 so 1 of the read timing generation circuit which is the main part of the digital transmission system in Figure 1, Figure 7 (bow, same digital transmission 7 stems) Figure 8 is a block wiring diagram of the restoration circuit for color TV 1.
．． FIG. 1 is a waveform diagram of a clock signal for restoring No. 1 and a waveform for reducing the ratio of 1:0. 1○2 ・ Drifting ratio timing generation circuit, 103 sampling circuit, 104-...quantization circuit, 105°111
Memory circuit, 1○6 ・Encoding circuit, 107.108
-・Modem, 109・Decoding circuit, 11O・・Reading timing generation circuit, 112・Color TV signal restoration circuit, 113・・Inotal analog conversion circuit 1, Name of agent: Patent attorney Toshio Nakao Haga 1st person 1
Figure 2 Figure 3 Crane Figure 4 (c+ /d) 5th (2)

Claims (1)

[Claims] Defined as a thousand-sided synchronization signal, water synchronization signal, and subcarrier signal;
The color television signal is sampled with a pulse having a frequency in a ti/c phase relationship that is an integer fraction of twice the subcarrier signal frequency, and the vertical synchronization signal is obtained. Wednesday, 11, 1υ] The phase relationship and frequency with the Iroyu-1 subcarrier signal are the same as the 1-th sampling pulse. Restoring Kashi TVi No. 13's Isshohon Kairiho method 1.