JPH0528958B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a color video signal transmission system, and in particular to converting a composite color video signal into a special component state signal (pseudo component signal) that does not have a color subcarrier. The present invention relates to a color video signal transmission method for transmitting a composite color video signal and restoring a pseudo component signal to an original composite color video signal.

2. Description of the Related Art In general, when handling composite color video signals with a VTR, it is necessary to carefully consider three points: the influence of time axis fluctuations, frequency bands, and waveform distortion (spurious). Here, the "direct color process method" used in broadcast VTRs addresses these considerations without compromise, but on the other hand,
For example, color video signals are recorded and played back by direct frequency modulation (FM) at a high tape head relative speed of about 25 to 40 m/s, which requires a high-precision mechanism, large-scale circuitry, and a large amount of tape. The disadvantage is that a large amount is required.

On the other hand, in the "color under method" used in consumer or industrial VTRs, the relative speed of the tape head is relatively low, for example, on the order of several m/s, and the color signal is transferred to the FM band of the luminance signal. Since the frequency is converted to a lower frequency of around 700 kHz and the FM luminance signal is superimposed for recording and playback, the drawbacks of the above-mentioned broadcasting VTR have been improved.

Problems to be Solved by the Invention By the way, the "direct color process method" and "color under method" in the above-mentioned VTRs
If we view the color video signal processing method as a type of color video signal transmission method, in the conventional color video signal transmission method such as the above-mentioned "color under method", the amount of information contained in the composite color video signal is actually has the disadvantage that only about 1/2 of the data is transmitted. Due to this lack of information, for example,
There have been problems in the reproduction of VTR images, such as insufficient resolution, sharpness and color resolution, and lack of detail.

Therefore, the present invention converts a composite color video signal into a pseudo component signal and transmits the signal.
It is an object of the present invention to provide a color video signal transmission system that solves the above problems by restoring the pseudo component signal to the original composite color video signal.

Means for Solving the Problems FIGS. 1A and 1B are block diagrams showing the configuration of the color video signal transmission system according to the present invention, respectively. Here, the method of the present invention shown in FIG.
It is composed of a D conversion means 1, a data conversion means 2, and a D/A conversion means 3. The A/D conversion means 1 converts the composite color video signal into a sampling frequency n·fsc.
(where n is an integer of 2 or more, and fsc is the color subcarrier frequency) and outputs the first data obtained by sampling. The data conversion means converts the first data into a group of first data having the same phase with respect to the color subcarrier of the composite color video signal at every sampling period of 1/fsc within one horizontal scanning period. Then, the first data of the n groups are arranged in series for each group in units of one horizontal scanning period, and the obtained second data is output. The D/A conversion means converts the second data into an analog video signal and outputs it to the transmission path.

Next, the method of the present invention shown in FIG.
A first A/D conversion means 1', a first data conversion means 2', and a first D/A conversion having the same functions as the D conversion means 1, the data conversion means 2, and the D/A conversion means 3, respectively. The means 3' includes a second A/D conversion means 4,
The configuration includes second data conversion means 5 and second D/A conversion means 6. Here, the second A/D conversion means 4 converts the first
The output analog video signal of the D/A conversion means is analog-to-digital converted to restore and output the second data. The second data conversion means 5 is
Data of each sampling point is extracted one by one from each group from the n groups of data in the second data from the second A/D conversion means, and the first data is restored and outputted again. . Second D/A conversion means 6
performs digital-to-analog conversion on the first data from the second data conversion means, and composites and outputs the original composite color video signal.

Operation After the composite color video signal is converted into first data via the A/D conversion means 1, it is supplied to the data conversion means 2, where it is converted into second data. This second data includes n groups of in-phase sampling point data during one horizontal scanning period (1H). This second data is transmitted to the D/A conversion means 3
The signal is digital-to-analog converted into an analog video signal corresponding to the pseudo component signal.

Next, the analog video signal passes through the transmission path and then passes through the second A/D conversion means 4, the second data conversion means 5, and the second D/A conversion means 6, respectively. Signal processing is performed in the opposite manner by the D conversion means 1, data conversion means 2, and D/A conversion means 3, and the original composite color video signal is finally restored.

Next, first and second embodiments of the system of the present invention will be described with reference to FIGS. 2 to 6.

Embodiment FIGS. 2A to 3E and 3A to 3E are diagrams explaining the principle of a first embodiment of the color video signal transmission system according to the present invention, respectively. Here, to explain the case where the method of the present invention is applied to the recording and reproducing system of a VTR as an example, FIGS. An example block system diagram is shown.

In FIG. 5, a composite color video signal as shown in FIG.
and the timing pulse generation circuit 10, respectively. By the way, as is well known, the above composite color video signal has a color subcarrier frequency fsc (for example, NTSC
fsc=3.58MHz for PAL method, fsc=3.58MHz for PAL method
This is a signal obtained by band-sharing multiplexing a carrier color signal obtained by orthogonally modulating a color subcarrier (fsc=4.43MHz) with two types of color difference signals into a luminance signal.

The timing pulse generation circuit 10 separates a horizontal synchronization signal from the incoming composite color video signal, and generates a timing pulse P with a period of one horizontal scanning period (1H) obtained by waveform shaping the horizontal synchronization signal.
The signal is supplied to a phase locked loop (PLL) 11 and a control device 12, respectively. Based on the incoming timing pulse P, the PLL 11 operates at a frequency of, for example, 3fsc (in the case of the NTSC system, 3fsc≒10.7MHz).
A pulse signal P ₁ of 1 and a 3-phase pulse signal P ₂ of a frequency fsc whose phases are shifted by, for example, 120 degrees from each other are generated and supplied to the control device 12, respectively.

Based on the pulse signal P1, the control device ₁₂ generates a sampling pulse Ps with a frequency of 3 fsc, a write control signal _PW , a read control signal _PR , and a pulse signal _P3.
are generated and supplied to the A/D converter 9, random access memory (RAM) 13, and D/A converter 14, respectively, and the pulse signals _P1 and
Based on P ₂ , generate address signal P _A to
13.

The A/D converter 9 samples the incoming composite color video signal with the sampling pulse P _S having a sampling frequency of 3fsc to generate digital data with, for example, 7 or 8 bits of quantization bits per sampling point. do. Here, the second
FIG. B shows a relationship diagram between the color subcarrier and each sampling point, and each mark on the color subcarrier indicates each sampling point. In FIG. 2B, since the sampling frequency is three times the color subcarrier frequency fsc, three types of sampling points having mutually different phases appear during one cycle of the color subcarrier. If each sampling data at these three types of sampling points is respectively a ₁ , b ₁ , c ₁ (or a ₂ , b ₂ , c ₂ etc.), the A/D converter 9 has a quantization bit number of 7 bits. Or digital data a ₁ , which is obtained by sequentially chronologically synthesizing the above 8-bit sampling data.
b ₁ c ₁ , a ₂ , b ₂ , c ₂ . . . are generated and output to the RAM 13.

The RAM 13 has a storage capacity of at least 2H, and is for rearranging _and outputting incoming digital data _. After that, data is written every sampling period 1/fsc, with 1H as a delimiter, and the phases of each sampling data with respect to the color subcarrier of the composite color video signal are in phase with each other (same phase data). comrades as one group, data a ₁ , a ₂ ... of group a, data b ₁ ,
b ₂ ... and data c ₁ , c ₂ ... of group c are generated, respectively.
Next, the RAM 13 arranges the data of groups a to c in series in the order of groups a, b, and c, as shown in FIG. 2C, and sends the readout control signal P _R
The data is read out to the D/A converter 14 according to the data.

The D/A converter 14 performs digital-to-analog conversion (D/A conversion) on the incoming digital data from the RAM 13, and compresses the time axis to 1/3 within 1H, as shown in FIG. 2D. Then, an analog video signal in which three color video signals a, b, and c are arranged is generated and outputted to the FM modulator 16 via the emphasis circuit 15.

The FM modulator 16 performs frequency modulation (FM) on the incoming analog video signal and outputs a frequency modulated (FM) analog video signal to the recording amplifier 17 . The recording amplifier 17 receives a pulse code modulated (PCM) audio signal (PCM) from the input terminal 18.
The audio signal) and the FM analog video signal are supplied to rotary heads _H1 and _H2 mounted 180° opposite to a rotary head drum (not shown). As a result, the PCM audio signal and FM analog video signal are recorded on a magnetic tape (not shown) (FIG. 2E).

Here, taking the NTSC system as an example, the bandwidth required to transmit the analog video signal is 5.4M.
Hz (≒3fsc/2) or higher, and when recording and reproducing the above analog video signal on a VTR, the VTR must be able to pass this band sufficiently.

Next, the operation of the reproduction system of a VTR to which the method of the present invention is applied will be explained with reference to FIGS. 3A to 3E and FIG. 6. Here, FM reproduction signals reproduced from the magnetic tape by rotary heads _H1 and _H2 are supplied to a switch circuit 21 via preamplifiers 19 and 20, respectively. The switch circuit 21 is connected to a rotating head.
The output signals of the preamplifiers 19 and 20 are switched and outputted alternately in response to switching signals from the input terminal 22 corresponding to the magnetic tape sliding scanning periods of H ₁ and H ₂ . As a result, a continuous FM reproduction signal can be obtained. The output of this switch circuit 21
The FM playback signal is passed through the equalizer circuit 23.
The PCM in the output FM playback signal is supplied to the FM demodulator 24 and dropout detector 25.
The audio signal is outputted to an audio signal processing section (not shown) via the output terminal 26.

The FM demodulator 24, as shown in FIG. 3A, performs FM demodulation of the incoming output FM playback signal, and outputs a playback signal as shown in FIG. 3B to an A/D converter 27 and a timing pulse generation circuit 28. Output to each. The timing pulse generation circuit 28 separates the horizontal synchronization signal from the incoming reproduction signal, generates a timing pulse P' obtained by waveform shaping the horizontal synchronization signal, and supplies the generated timing pulse P' to the PLL 29 and the control device 30, respectively.
Based on the incoming timing pulse P', the PLL 29 generates a pulse signal P1' of frequency 3fsc and a pulse signal P1 _' of frequency fsc
The three-phase pulse signals P ₂ ' are generated and supplied to the control device 30, respectively. On the other hand, a clock circuit 32 having a crystal oscillator 31 generates a reference clock signal P ₄ having a frequency of 3 fsc and outputs it to the control device 30 .

The control device 30 generates a sampling pulse P _S ′ and a write control signal P _W ′ based on the pulse signal P ₁ ′.
is generated and supplied to the A/D converter 27 and the RAM 33, respectively, and an address signal P _A ' is generated and supplied to the RAM 33 based on the pulse signals P ₁ ' and P ₂ '. Furthermore, the control device 30 generates a read control signal _PR ' and a pulse signal _P3 ' based on the reference clock signal _P4 , and supplies them to the RAM 33 and the D/A converter 34, respectively.

Incidentally, since the output reproduction signal of the FM demodulator 24 includes a time axis error (jitter), the output pulse signals P ₁ ' and P ₂ ' of the PLL 29 also include jitter. Therefore, the control device 3
The sampling pulse P _S ′, write control signal P _W ′, and address signal P _A ′ output from 0 will also contain jitter similar to that of the reproduced signal. Therefore, the A/D converter 27 and RAM 33, which will be described later,
Since signal processing is performed on signals that each include jitter, there is no effect of jitter associated with this signal processing. Thereafter, the D/A converter 34 converts the jitter-free reference clock signal _P4 .
The digital data is read out from the RAM 33 using the readout control signal P _R ' and the pulse signal P ₃ ' generated based on the data and is subjected to D/A conversion, so that an analog playback signal containing no jitter is obtained. In this way, compensation for jitter is provided.

The A/D converter 27 samples the reproduced signal as shown in FIG. 3B based on the sampling pulse P _S ', and converts the reproduced signal into the signal shown in FIG. Convert to digital data as shown in
Output to 3. In this digital data, each data group having the same phase per 1H is arranged in series in the order of group a, group b, and group c.

Like the RAM 13, the RAM 33 has a minimum
It has a storage capacity of 2H, writes incoming digital data to a predetermined address according to the address signal P _A ′ and write control signal P _W ′, and then
One piece of data is extracted from each group of data in order, and each data is divided into a ₁ , b ₁ ,
Digital data arranged in the order of c ₁ , a ₂ , b ₂ , c _{2 .} . . is generated and read out to the D/A converter 34 in response to the read control signal _PR '.

The D/A converter 34 performs D/A conversion on the digital data in accordance with the pulse signal P ₃ ', ultimately restoring the original composite color video signal as shown in FIG. Output.

On the other hand, when the dropout detector 25 detects that a dropout has occurred in the incoming reproduction signal, it generates a detection signal and sends a detection signal to the control device 30.
Output to. In this case, the control device 30 controls 2H in which the subcarrier phase is the same as the current horizontal scanning period.
The previous digital data is read from the RAM 33 and output to the D/A converter 34. The D/A converter 34 D/A converts the incoming digital data 2H ago and outputs it to the output terminal 35 as a composite color video signal for the current horizontal scanning period.

In this way, by grouping the same-phase data in the composite color video signal, the composite color video signal becomes as if it were a component signal, which is a disadvantage of the conventional composite color video signal transmission using subcarriers. For example, if the VTR is viewed as a transmission system for composite color video signals and the system of the present invention is applied to the VTR, the following advantages can be obtained.

The band of the luminance signal is generally 4.2MHz,
On the other hand, the video signal transmission band according to the present invention method is
For example, in the case of the NTSC system, since the frequency is 5.4MHz or higher, the brightness signal can be completely restored during VTR playback.

Since there are no subcarrier components with large energy in the high frequency range, the method of the present invention is suitable for FM transmission.

Stable color signal transmission is possible against time axis errors (jitter).

No special color process circuit is required for both the recording and playback systems of the VTR.

Only the azimuth head can support guard bandless recording.

Since single-frequency recording is possible, spurious interference does not occur.

Since there is no Y/C separation, high resolution can be obtained (for example, in the case of NTSC, the number of scanning lines is 430).
A time base corrector is also used to obtain a composite color video signal that ensures interleaving.

As shown in FIGS. 5 and 6, the signal processing according to the present invention may be performed using a digital circuit or, for example, a charge-coupled delay element (CCD delay element).
may be used.

Furthermore, like the NTSC system, the PAL system also has the regularity of in-phase sampling points for color subcarriers, so the first embodiment can also be applied to composite color video signals of the PAL system.

FIG. 4 shows a principle explanatory diagram of a second embodiment of the system of the present invention. Regarding this second embodiment,
Only signal processing during VTR recording will be explained.

The second embodiment is characterized in that signal processing according to the present invention is performed on a video information signal section other than the horizontal or vertical synchronization signal section in a composite color video signal. First, signal processing similar to that described above is performed on the video information signal section other than the horizontal synchronization signal section in the composite color video signal as shown in FIG. After generating the 1H color video signals A, B, and C, the above-mentioned horizontal synchronization signal section is added to generate a 1H analog video signal as shown in FIG. 4B.

Further, in this case, the vertical synchronization signal section is also handled in the same manner as above. That is, as shown in FIG. 4C, the same signal processing as described above is performed on the video information signal section other than the vertical synchronization signal section from the composite color video signal of one field period (1V), and then the vertical synchronization signal section is Add a synchronization signal section,
Generates a 1V analog video signal.

According to the second embodiment, the following advantages can be obtained.

It becomes easier to identify (or distinguish) the 1H section.

When performing digital signal processing, less memory capacity is required.

Since the shapes of the horizontal and vertical sync signals are not tampered with, the sync signal information is not lost.

Effects of the Invention As described above, according to the present invention, the composite color video signal is converted into the pseudo component signal and transmitted, and the pseudo component signal is restored to the original composite color video signal. When this method is applied to a VTR, composite color video signals can be recorded and played back as component signals, making it resistant to jitter and free from spurious interference. This eliminates the problem of FM modulation, making it easier to record and reproduce data, and it also has the advantage of being able to sufficiently reproduce and restore the amount of information contained in the composite color video signal.

[Brief explanation of the drawing]

1A and 1B are block system diagrams showing the configuration of the color video signal transmission system according to the present invention, and FIG.
Figures A to E and Figures 3 A to E are explanatory diagrams showing the first embodiment of the method of the present invention, respectively; Figures 4A to C are diagrams explaining the principle of the second embodiment of the method of the present invention; 6 and 6 are block diagrams respectively showing an example of a recording system and a reproducing system of a VTR to which the method of the present invention can be applied. 7...Composite color video signal input terminal, 8...Automatic gain control circuit (AGC circuit), 9, 27...A/
D converter, 10, 28... Timing pulse generation circuit, 11, 29... Phase locked loop, 12, 30... Control device, 13, 33... Random access memory (RAM), 14, 3
4...D/A converter, 15...Emphasis circuit, 16...FM modulator, 17...Recording amplifier,
18...PCM audio signal input terminal, 19, 20...
...Preamplifier, 21...Switch circuit, 22...
Switching signal input terminal, 23... Equalizer circuit, 2
4...FM demodulator, 25...Dropout detector, 26...PCM audio signal output terminal, 31...
Crystal resonator, 32...Clock circuit, 35...Composite color video signal output terminal, _H1 , _H2 ...Rotating head.

[Claims]

1 Color subcarrier frequency fsc of composite color video signal
pulse generating means for respectively generating and outputting a sampling pulse and a control signal having a frequency n (where n is an integer greater than or equal to 2) times the frequency of A, and A for sampling the composite color video signal with the sampling pulse and outputting sampling data. /D converter, and a group of sampling data of each sampling period 1/fsc that have the same phase with the color subcarrier of the composite color video signal within one horizontal scanning period, in total n. storage means for converting the n groups of sampling data into data of groups and reading out the n groups of sampling data by arranging them in series for each group in units of one horizontal scanning period according to the control signal; and converting the output data of the storage means into analog video A color video signal comprising a D/A converter that converts it into a signal and outputs it, and a recording means that frequency-modulates the output analog video signal of the D/A converter and records it on a magnetic recording medium. Magnetic recording device. 2 Color subcarrier frequency fsc of composite color video signal
a first pulse generating means that generates and outputs a first sampling pulse and a first control signal having a frequency n (where n is an integer of 2 or more) times the frequency of sampling pulse

Claims (1)

a first A/D conversion means for outputting first data obtained by sampling at a transmission frequency); and a first A/D conversion means for outputting first data obtained by sampling at a transmission frequency); The first data of each sampling period 1/fsc that have the same phase are converted into n groups of data in total, and the first data of the n groups are divided into each group in units of one horizontal scanning period. a first data converting means for outputting second data obtained by arranging the data in series, and a first data converting means for converting the second data into an analog video signal and outputting it to the transmission path.
a D/A converting means, and a second D/A converting means for performing analog-to-digital conversion on the output analog video signal of the first D/A converting means, which is inputted through the transmission path, and restoring and outputting the second data. 2 A/D conversion means;
From the n groups of data in the second data from the second A/D conversion means, data at each sampling point is extracted one by one from each group, and the first data is restored again. a second data converting means for outputting, and a second D/A converting means for digital-analog converting the first data from the second data converting means to restore and output the original composite color video signal.
A color video signal transmission system characterized by comprising A conversion means.