KR930006538B1 - Color-under chroma channel encoded with auxiliary signals - Google Patents

Abstract

The chroma channel system processes video signals of a video tape recorder which utilizes separated channels to record chroma signal and luminance signal. The chroma channel system includes a chroma carrier signal generator (16) for generating 3.58 MHz continuous wave carrier signal, a burst gate (25) for looking phase and frequency of carrier signal to input burst signal, a video signal supply (10) for supplying video signal to a synchronous signal divider (24) and a burst gate of the burst gate (25), a frequency divider (26) for dividing frequency of horizontal synchronous signal by halves, a multiplexer (20) for generating phase alternate carrier signal according to chroma carrier signal and horizontal synchronous signal, and a modulator (34) for modulating phase of a first auxiliary signal.

Description

Chromatic Channel System Encoded as Auxiliary Signal

1 is a block diagram of a color-under system according to the present invention.

2 is a block diagram illustrating a system for decoding or reproducing a color-undersized chroma signal.

3 shows the relative positions of chroma signals and chroma signals decomposed from the respective I and Q signals.

4 shows an embodiment of an auxiliary signal demodulator for two auxiliary signals, and

5 is a diagram showing another embodiment of an auxiliary signal demodulator for only one auxiliary signal.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for processing a video signal comprising chroma and luma signals, and more particularly to a video tape recorder in which separate channels are used to record a predetermined chromaticity signal on magnetic tape. The invention relates to the processing of video signals in a video tape recorder.

In the recording system of a video signal, it is known to modulate and adjust the chromaticity signal normally appearing in the lower spectrum of a given composite television signal to the spectral position below the luminance signal. Such modulation or down-conversion systems in the video art are known as so-called "color-under" recording systems. In such a color-under system, the in-phase (I) component and the quadrature (Q) component of chromaticity information are processed in a conventional manner to generate a color signal C for viewing a predetermined picture.

Color VCR (Video Cassette Recorder) In the art, it conveys auxiliary signals useful for color television signals, such as digital audio information and / or signals related to operations occurring in a given video picture. There is a need to provide additional channels for.

The present invention utilizes, in its optimal form, a color-under chromaticity channel for carrying additional information such as signals and / or digital audio signals that makes the operation taking place on a given picture scene more clear.

A predetermined phase alternating carrier (PAC) is a typical 3.58 MHz (= 455f) signal due to line-to-line multiplexing and its 180 ° phase shifted signal. _h / 2) is also generated from the carrier signal. Therefore, the phase alternating carrier signal has a phase that is 180 degrees different from the alternating lines with respect to the phase of the chromaticity carrier signal, that is, the phases of the odd lines are different in phase and the phases of the even lines are equal in phase.

The PAC signal is modulated with the first auxiliary signal, and the PAC signal with 90 ° phase shift is modulated with the second auxiliary signal. These two modulated PAC signals are added together to provide a predetermined signal, referred to herein as a phase alternating signal (PAS). This PAS signal is then combined with a normal modulated chromaticity carrier signal, referred to herein as a chroma signal (Ca) signal. The sum of these two signals is referred to herein as an "augmented chroma signal." In a VHS system, the enhanced chroma signal is down-modulated as a color-under signal at a frequency of 629 KHz (= 40 f _h ). The augmented chromaticity signal, together with the processed luminance signal, is supplied to a predetermined recording medium or other transmission medium used on a real time basis, or to be used at a desired subsequent time. Stored in tape or other storage means.

The reinforcement chroma signal is decoded (or reproduced) only by reversing the encoding process as a network of adders and line delay means, where the chroma signal C and the phase alternating signal PAS are separated The original chromaticity signal and auxiliary signal are output to each separate output stage for use in the desired playback device.

The present invention is carried out in view of a television (hereinafter referred to as TV) signal processing system according to the NTSC scheme adopted in the United States. Nevertheless, the principles of the present invention can be applied to a PAL type system mainly used in Europe. Further, the present invention can be applied to a color TV transmission or recording system in which the chroma signal is not interleaved with the luminance signal based on the standard NTSC color TV system.

A preferred embodiment of the present invention will be described with reference to the block diagram of FIG.

The source 10 of the digital video signal is provided with the luminance signal Y to the luminance processor 14 and the chroma signal C to the 3.58 MHz chroma carrier signal oscillator 16. C) It is connected to the separating part 12. The Y / C separation unit is preferably in the form of using 1-H combing of chroma signals. The luminance processing unit 14 of the conventional type mainly used in the video recording art outputs an FM modulated luminance signal connected to the adder 18.

The chroma signal C is connected to the oscillator 16 and the adder 42. The chromatic carrier signal oscillator 16 provides a continuous wave (CW) carrier signal of 3.58 MHz, which is frequencyd to an input burst signal gated by a burst gate in the passage 25. And the phase is locked. The oscillator 16 outputs a chroma-burst-locked 3.58 MHz CW signal (at 0 ° phase) to the multiplexer (MUX) 20 and the 180 ° phase shifter 22.

The video signal source 10 is also connected to a synchronization separator 24 which generates a horizontal synchronization signal H and a burst gate on the passage 25. The horizontal synchronizing signal (H) is applied to the two-dividing circuit (26), thereby providing a horizontal signal (H / 2) for controlling the MUX (20). The MUX 20 responds to the chromaticity carrier signal at 0 ° and 180 °, respectively, and outputs a phase alternating carrier signal PAC at the output 28. The appropriate phase (N °) of this PAC is selectively related to the output signal phase of the oscillator 16 by a look-up table 30 (hereinafter " LUT "). In this embodiment, the angle of the MUX output is 57 ° ahead or 33 ° delayed with respect to the mentioned 3.58MHz chromaticity carrier signal, mainly because of the low cost of achieving this system in this case. However, in some applications it may be desirable to have a different phase. Furthermore, the ability to direct the selection of horizontal lines for the phase of the PAC may be implemented with programmable read-only-memory (PMOM). If you use a PROM, you will get an accurate and noiseless PAC.

The degree of supply from the signal source 32 is preferably a low-pass 1-H combed, and the first auxiliary signal AUX1 is connected to one input of the adder 36. ) Is modulated in accordance with one phase of the PAC at the output of the LUT 30. Also, preferably, the low pass 1-H combed second auxiliary signal AUX2 is quadrangled with the AUX1 signal by a 90 ° phase shifted PAC from the phase shifter 41 connected to the output terminal of the LUT 30. ) May be modulated. The AUX1 signal may be a properly encoded digital audio signal derived from a mono or stereo TV audio system, not shown.

Furthermore, the second auxiliary signal may be a predetermined control signal useful for operating the reproduction system. Such a signal may be a predetermined motion signal indicative of an operation generated in an image scene. Appropriate techniques known in the art may be used to derive any of the electrical auxiliary signals. As will be apparent to one of ordinary skill in the art, other control signals may be used to be encoded on the phase alternating carrier signal PAC. Hereinafter, a preferred form of decoders for the auxiliary signals will be described with reference to the drawings of FIGS. 2, 4 and 5.

In the adder 36 whose output side is connected to the input of the adder 42, the respective modulated phase-shift carrier signals PAC carrying the auxiliary signals AUX1 and AUX2 are added to each other. The second input end of the adder 42 is coupled to the chroma signal C derived from the Y / C separator 12. The output of adder 42 is a reinforced chromaticity signal that includes a chromaticity signal encoded with chromaticity information and a combined phase-change carrier signal (s) encoded with one (or multiple) auxiliary signal (s). The present invention can be applied to a color TV transmission system in which the chromaticity signal is not interleaved with the latitude signal based on the standard NTSC color TV system.

However, the most suitable embodiment of the present invention is useful for video recording systems whose transmission path is magnetic tape. Since magnetic tapes currently used in the industry are of limited bandwidth, a signal equivalent to the output of the adder 42 is remodulated in the modulator 44 into the lower spectrum of the latitude channel so that the electric chromatic carrier signal is called a " color " Is required due to the magnetic tapes to be placed in the form of "under". Typically, the electrical color-under carrier signal has a frequency of 629 KHz (= 40f _h ) in the VHS system.

A means of generating signals in color under form is described.

The output of the adder 42 consisting of the chroma signal C and the PAS signal from the adder 36 are coupled in the passage 43 to the first input of the modulator 44. The second input signal of the modulator 44 allows the modulator 46 to pass only the sideband of 4.21 MHz to the modulator 44. The modulator 46 has two inputs, one is a 0 ° phase CW chromatic conveyance signal from the oscillator 16 and the other is 629 KHz connected to the output of a 90 ° -phase shifter 49a per H-line. (= 40f _h ) This is a carrier signal. The electrical 629 KHz carrier signal is locked in frequency and phase to the input video signal because of the 30 Hz switching signal derived from the recorder and the horizontal derived from the video to identify the two recorded tracks on the magnetic tape. This is because the phase shifter is coupled to the 629 KHz oscillator 48 under the control of the synchronization signal H. The modulation product of modulator 44 has a periodic auxiliary signal (s) and a chroma signal modulated with a 3.58 MHz carrier signal ± 4.21 MHz carrier signal. The low pass filter 51 passes only the 629 kHz sideband. The 629 dB carrier signals are known as color under carrier signals. The modulated 629 kHz signal is also the color under signal used in the present invention. The color under signal and the fm luminance signal pass through an adder 18 for writing on magnetic tape. The input of the recorder thus consists of an fm luminance signal and two color under carrier signals, each modulated with the chromaticity and auxiliary signal (s).

It is understood that the processing of a phase alternating carrier signal modulated with one or two auxiliary signals is similar to modulating a predetermined chromaticity carrier signal at 0 ° and 90 ° with I and Q chromatic components, respectively, to produce a chroma signal. It will be understood by one of ordinary skill in the art. Thus, the modulated auxiliary signals of the present invention are very similar in concept of quadrature modulation to the I and Q signals of a typical chromaticity signal.

3 illustrates a detailed operation of the system of FIG. 1 in conjunction with a vector diagram. Referring to FIG. 3 and the two carrier signals, chromaticity and vector diagram of the PAC shown in Tables I and II below, each phase increment of the carrier signals through two frames and a plurality of operation lines is obtained. Shown. In normal operation, according to the NTSC standard, a 3.58 MHz carrier signal is 180 ° phase alternating on each continuous line scanned. At the beginning of the first and second fields on lines 1 and 263 of the first video frame, the phase of the chromaticity carrier signal is 0 degrees. However, at the beginning of the first and second fields of the second frame, the phase of the chromaticity carrier signal is at -180 °. Moreover, it should be understood that the phase of the PAC is 0 ° at the beginning of each field of the first and second frames. Table I below shows these phase values.

TABLE 1

The relative positions of the vectors I and Q of the auxiliary signals AUX1 and AUX2 are shown in FIG. In this embodiment, the angle value N of the phases of the signals AUX1 and AUX2 shown as S1 and S2 in FIG. 3 is equal to the phase angle of the I and Q signals. As mentioned above, N can be any desired value. It will be apparent to those of ordinary skill in the art that the figures will be more complicated if they illustrate other values of N, and this is not necessary to understand the operation of the present system.

It should be appreciated that the location of the I and Q vectors will remain constant with respect to the chroma burst vector, but nevertheless it alternates line to line. However, since the PACs carrying the auxiliary signals AUX1 and AUX2 fluctuate with respect to the chromaticity carrier signal, as shown in FIG. 3, the auxiliary signals are in phase with the I and Q signals for odd lines, It is out of phase.

Analyzing the phase progression of the color under chromaticity carrier signal at 629 Hz, the phase angle of the 629 Hz carrier signal is delayed by 90 ° per H-line with respect to the first field, and then the process is reversed to reverse the process. It will depend on a good understanding of the VHS standard, which is set 90 ° per H-line for the second field. Details of such phase change will be described with reference to Table II.

As indicated in Table II, the electric PAC color under carrier signal is in phase with the chromaticity color under carrier signal on odd lines, and is 180 ° or more on even lines in frame # 1. This is due to the forced change of the PAC carrier signal phase as described above. It is shown in Table II that two 629 dB carrier signals on any two given adjacent lines in one frame are always abnormal in one line and in phase on the other line. The relative positions of the I and Q vectors and the auxiliary signal vectors S1 and S2 remain the same for the color under mode as shown in FIG. It should be understood that this table II relates to carrier signals without modulation.

TABLE 2

Referring to Fig. 2, a preferred form of the playback decoder will be described.

2 shows a block diagram of a decoder or playback system using the present invention.

The 629 KHz carrier signal and the fm luminance signal modulated with chromaticity and auxiliary signal (s) are applied to the passage 100 connected to the low pass filter 102 and the high pass filter 104, respectively. The high pass filter 104 transmits the fm luminance signal to a known luminance processing circuit 106.

The low pass filter 102 transmits its output to the 90 ° phase shifter 103. The present 90 ° phase shifter, similar to the phase shifter 49a of the encoder of FIG. 1, provides a phase shift of 90 ° per line. The 30Hz switching signal controls this 90 ° phase, advancing or delayed based on field # 1 or # 2. The phase shifter 103 transmits 629 KHz signals on the passages 108 and 110 to one input terminal of the adder 114 and the negative input terminal of the adder 112, respectively. The output of the phase shifter 103 is through the 1H delay element 111, and its output is connected to the second input terminals of the adders 112 and 114, respectively.

Thus, the chroma signal, from which the auxiliary signal information has been removed by the adder 112, passes through line 116 to a suitable color processing demodulator 118 that provides a baseband I and Q color component to the color utilization device 12. Delivered. Regarding the red color demodulator 118, a device for restoring the phase correction relationship between a chromaticity signal and a luminance signal passing through a separate passage, which is a patent application filed by the same applicant (Inventor: Chong Pat and CB Patel) (Apparatus for Restoring the Correct Phase Relation of the Chroma and Luminance Signals Passed through Separate Paths) ".

The 629 KHz carrier signals modulated only by the auxiliary signals, AUX1 and AUX2, are recovered as the output of the adder 114 and are also applied to the auxiliary signal processing circuit 124. The processing circuit 124 demodulates the PAC encoded as auxiliary signals and provides them with separate outputs 126, 128 for the desired use.

4, a preferred processing circuit 124 is shown. The enhanced chroma signal is connected to one input of the adder 114 and the 1-H delay line 111. This 1-H delayed signal is applied to the other input of the adder 114. The output of the adder 114 is a PAS signal guided through the passage 122 to each input of the modulators 130, 132. The output of the chromatic oscillation portion 16 on the passage 133 is applied to the N ° phase shifter 134 and then also to the multiplexer 136. This MUX 136 provides a line separator directly to the modulator 130 or via the 90 ° phase shifter 138 in a manner similar to the MUX 20 of the encoder of FIG. The modulators 130 and 132 demodulate the encoded carrier signals to extract the respective auxiliary signals AUX1 and AUX2 after passing through the low pass filters 140 and 142. The auxiliary signal demodulator or processing circuit shown in FIG. 4 is useful for demodulating two auxiliary signals, and may be useful even if only one auxiliary signal is demodulated. However, for a system in which only one auxiliary signal is to be demodulated, a simpler and more efficient circuit as shown in FIG. 5 can be used.

5 corresponds to a reinforced luminance signal with a PAS, showing that only one auxiliary signal passes through the 1H delay element 11 and the adder 114. The output of this adder 114 is connected to an envelope detector 150 that includes an absolute detector 152 such as a PROM, which in turn is connected to a low pass filter 154. The output is an auxiliary signal provided from the signal source 32 or 38 of FIG.

Although the present invention describes the use of a 3.58 MHz luminance carrier signal and the modulation of the 629 KHz color under carrier signal, the present invention can also be implemented as a baseband chromaticity signal for directly modulating the 629 KHz carrier signal.

Furthermore, for other similar systems, such as the PAL and Beta tape systems, in which the chromaticity carrier signal is encoded in a different phase relationship than the above-described VHS format, the alternating carrier signal so encoded in the phase shift with respect to the chromaticity carrier signal. The present invention may be implemented by a system having a.

The embodiment of the present invention described above alternates the carrier signal, which is later encoded with one or two auxiliary signals. However, it will be understood by those skilled in the art that the process may be reversible. Therefore, the above-mentioned carrier signal may be encoded as preferred auxiliary signals first and then the phase may be changed. Otherwise, the above-described process will be carried out as it is. Meanwhile, the present invention has been described as being applied to the specific embodiments illustrated, but is not limited to the above embodiments and various modifications and changes without departing from the spirit of the invention. This will be possible.

Claims (28)

A video signal processing system having a chromaticity carrier signal modulated with chromaticity information, the video signal processing system comprising: means for reacting to the chromaticity carrier signal to generate a predetermined phase alternate carrier signal, wherein the phase alternate carrier signal and the chromaticity carrier signal are alternating; Means for causing a phase shift of 180 ° on a scan line, means for modulating a first auxiliary signal on the phase alternate carrier signal, and means for adding the phase alternate modulated carrier signal to the modulated chromaticity carrier signal at a given phase angle; System. 2. The apparatus of claim 1, further comprising: modulation means for generating a color under chromaticity carrier signal in which a 180 ° phase is inverted in a line-to-line and frame-to-frame manner in response to the chromaticity carrier signal and a phase alternating carrier signal. And the color under phase alternate carrier signal further comprises the modulating means to be out of phase by 180 ° relative to the color under chromaticity carrier signal. 2. The apparatus of claim 1, wherein said modulated phase alternate half sign further comprises means for adding said second auxiliary signal to said phase alternate carrier signal, said first and predetermined second auxiliary signals. System. The system according to claim 1, wherein said phase alternating carrier signal generating means has a PROM. The system of claim 1, wherein the first auxiliary signal is a digital audio signal. 6. The system of claim 5, wherein the audio signal has a frequency multiplexed signal of one or more audio signals. The system of claim 1, wherein the first auxiliary signal is a signal indicating movement of the video signal. 4. The system of claim 3, wherein the first auxiliary signal is a digital audio signal and the second auxiliary signal is a signal indicating movement. 3. The system of claim 2, wherein the phase alternating carrier signal is in a phase relationship of 0 [deg.] To the phase of the color under carrier signal. A method of operating a video signal processing system having a predetermined chromaticity carrier signal modulated with chromaticity information, the chromaticity carrier carrying a predetermined phase alternate carrier signal in a 180 ° phase inversion relationship from line to line with respect to the chromaticity carrier signal. Generating, in response to the signal, the phase alternating carrier signal to be 180 degrees out of phase with respect to the color under chromaticity transport signal, modulating the phase alternating carrier signal by a first auxiliary signal, and predetermined And adding the modulated phase alternating carrier signal to the chromaticity carrier signal at a phase angle of. 11. The method of claim 10, wherein the color-carrier signal is generated in response to the modulated chromaticity carrier signal and the modulated phase alternate carrier signal to generate a predetermined color-under chromaticity carrier signal whose phase is inverted by 180 ° from the chromaticity carrier signal. Method characterized by the steps. 12. The method according to claim 10 or 11, wherein the second signal, which is a phase alternating carrier signal modulated at right angles by a second auxiliary signal, is added to the first signal, wherein the encoded signal is the first and second auxiliary signals. And including the signals. 12. The method of claim 10, wherein the first signal modulating step modulates the phase alternate carrier signal as a digital audio signal. 14. The method of claim 13, wherein the audio signal comprises a time division multiplexed carrier signal having one or more audio signals. 11. The method of claim 10, wherein modulating the alternating carrier signal with the first signal comprises a signal indicating movement of a video scene. A video signal processing circuit having a predetermined chromaticity carrier signal modulated with chromaticity information, the video signal processing circuit comprising: means for responding to the chromaticity carrier signal to generate a predetermined phase alternating carrier signal; Means for modulating a first auxiliary signal on said phase alternating carrier signal in a 180 [deg.] Phase inversion skew system into a frame, wherein said modulated phase alternating carrier signal is in a relationship of at least 180 [deg.] With respect to said color under chromaticity carrier signal Means for adding the modulated phase alternate carrier signal to the chroma carrier signal at a predetermined phase angle, the chroma carrier signal being combined with the modulated phase alternate carrier signal modulated as the first auxiliary signal; Means, and in order to separate the chromaticity conveyance signal and the first auxiliary signal into separate output channels. The alternating phase carrier signal and the circuit, characterized by means adapted to, responsive to the color-under carrier signal. 17. The apparatus of claim 16, further comprising: modulation means for generating a modulated color under carrier signal corresponding to the modulated chromatic carrier signal and the modulated phase alternate carrier signal, respectively, in response to the chromaticity carrier signal and the modulated phase alternate carrier signal; The circuit further comprises. 17. The apparatus of claim 16, wherein the separating means comprises a combined modulated carrier signal and a 1-H delay line connected to a pair of adders, wherein the adder is the sum of two modulated carrier signals at one output thereof. Arranged to provide a difference of the modulated carrier signals at the output of the other adder, each adder configured to be connected to the delayed carrier signals at the output of the 1-H delay line. Circuit. 18. The apparatus of claim 17, further comprising: means for modulating the phase alternate color under carrier signal by a second auxiliary signal, wherein the auxiliary signal comprises the first and second auxiliary signals, and wherein the separating means carries the modulated alternate carrier. And said means adapted to separate both the signal and the modulated chromaticity carrier signal into respective separate channels. 20. The apparatus of claim 19, wherein the separating means comprises a 1-H delay line connected to the combined modulated carrier signal and a pair of adders, wherein the adder is configured to output the two modulated carrier signals at an output of one of them. And at the output of the sum and the other adders are arranged to provide a difference of the modulated carrier signals, each adder being connected to the delayed carrier signals at the output of the 1-H delay line. 19. The circuit of claim 18, further comprising means for demodulating said first auxiliary signal from a predetermined phase alternate color under carrier signal to demodulate said first auxiliary signal from said color under carrier signal. . Apparatus for transferring modulation means of two carrier signals to a remote location, the apparatus comprising means for encoding a modulated first transport signal and a modulated second transport signal, the signal being derived along a parallel scan line. In a non-modulated system, the source of a modulated first carrier signal which is to be out of phase 180 ° at a corresponding point along successive scan lines, in the unmodulated state, and in the unmodulated state, corresponding to the green scan lines. And a supply source of a modulated second carrier signal, said phases being in phase at the point, and adding means connected to said source. 23. The apparatus according to claim 22, further comprising means for being connected to said adding means and for conveying a substantial value of said modulated first and second transport signals to a predetermined remote point. 24. The apparatus of claim 23, further comprising: 1-H delay means having an input and an output connected to said remote point as a 1-H delay means for providing a delay of one scan line, and corresponding to a modulated signal of said phase alternating second carrier signal. The means having outputs of the delay means and inputs connected to the remote points, respectively, to provide signals, the output of the delay means being inverted from the output of the delay means to provide signals corresponding to the modulated signal of the first transport signal. Further comprising subtracting means having inputs respectively connected to the output. 23. The apparatus of claim 22, wherein the modulated phase alternating carrier signal has a component of their quadrature modulation modulated with first and second auxiliary signals, respectively. 23. The apparatus of claim 22, wherein the first and second carrier signals have the same frequency. 23. The apparatus of claim 22, wherein the first carrier signal is a color subcarrier signal of an NTSC system, and the second phase alternating carrier signal has the same frequency as the color subcarrier signal. 28. The apparatus of claim 27, wherein the means for conveying the corresponding values of the modulated first and second carrier signals to the remote point outputs the corresponding values of the modulated first and phase alternating carrier signals at some other frequency. Means for modulating the signals supplied by said adding means with a signal having a frequency different from any one of said first and phase alternating carrier signals, a recording connected for recording said signals provided by said modulation Means and means for outputting a carrier signal connected to said recording means and having a same phase relationship with respect to the same line as said modulated first and phase alternating carrier signal.