JPH03108986A - Device and method for recording color video signal - Google Patents

Abstract

PURPOSE:To record chrominance signal over a wide band by providing a band compression circuit to frequency-interleave the high area component of the chrominance signal, which is inputted in a recording circuit part, to a low area side and to execute the band compression of the chrominance signal. CONSTITUTION:A luminance signal Y inputted to an input terminal 1 is converted to an FM signal by an FM modulation 4 and supplied to a signal adder circuit 18 while removing the low frequency component by a high-pass filter HPF 5. On the other hand, two color difference signals R-Y and B-Y inputted from input terminals 2 and 3, the high area component is turned to the low area side by sampling, etc., and the frequency-interleave is executed. Afterwards, the band is limited in a horizontal direction and the signals respectively arrive at rectangular two-phase modulation circuit 14. Then, rectangular two-phase conversion is executed respectively by carriers for which the polarity of phase shift is made reverse for each field. The signals are inputted to an adder 18, added with the output of the HPF 5, inputted to a recording amplifier 19 and recorded to a magnetic tape. Thus, the frequency band of the chrominance signal to be recorded can be widened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color video signal recording device such as a video tape recorder (abbreviated as VTR) that records and reproduces a wideband color signal.

2. Description of the Related Art As a home or business VTR, a carrier wave signal low frequency conversion type VTR, so-called color under type VTR, has been put into practical use since around 1972 and has been widely used.

Problems to be Solved by the Invention In conventional color under system VTRs, the carrier wave number of the low frequency carrier color signal is set to about 629 KHz in the VH8 system, for example.
Therefore, there is a problem in that the color signal band is narrow, about 350 KHz.

Means for Solving the Problems In order to solve the above-mentioned problems and record a wideband color signal, the present invention frequency-interleaves the high-frequency components of the input color signal to the low-frequency side in the recording circuit section. It is equipped with a band compression circuit that performs band compression.

Operation According to the present invention, the frequency band of the color signal to be recorded is approximately twice as wide due to the above-described configuration.

In addition, even though the frequency is interleaved due to nine offsets, it is possible to perform band compression in which aliasing interference can be removed even in a high-density recording mode without a guard band.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of essential parts of an embodiment of the present invention. The explanation will be made using a luminance signal Y and two color difference signals (R-Y) and (B-Y) as input video signals, but it is also possible to use Y, I, Q or a signal demodulated from a carrier color signal. The same is true. In FIG. 1, the Y signal is input to input terminal 1, the (RY) signal is input to input terminal 2, and the (B-Y) signal is input to input terminal 3.

The Y signal input to the input terminal 1 is converted into an FM signal by the FM modulator 4. For example, assume that the FM signal frequency at the tip of the video synchronization signal (sync chip) is 3.4 MHz, and the frequency deviation (deviation rate) due to the video signal is 1 MHz. Then, the FM modulated signal is passed through a high-pass filter (H
Frequency components of 1 MHz or less are removed by PF)s and supplied to the signal addition circuit 18. On the other hand, the (RY) signal input through input terminal 2 enters the prefilter filter. The internal configuration of the prefilter is shown in FIG. The input (R-Y) signal is input to the input terminal 20 and first passes through the low-pass filter (LPF) 2.
After the band is limited to 900 KH1 in the horizontal direction of the screen in step 1, the 1H delay circuit 22 is activated for one horizontal opening period (abbreviated as 1H).
The delayed signal is added in an adder circuit 23 (a so-called 1H delay comb filter), and after being band-limited in the vertical direction of the screen of the video signal in three-dimensional frequency space and time, it is outputted from an output terminal 24 and sent to an interleave circuit 8. leading to. Similarly, the (B-Y) signal inputted from the input terminal 3 is also inputted to a prefilterf having the same configuration as the Buri filter e, and after being band limited in both horizontal and vertical directions, it reaches the interleaving circuit 9.

Incidentally, the input Y signal is branched to a synchronization separation circuit 12, where a horizontal synchronization signal and equalization pulse are extracted and supplied to two interleaving circuits 8.9. FIG. 3 shows an example of the frequency interleaving circuit shown in FIG. 1, 8.9.

The horizontal synchronization signal and equalization pulse train which are the outputs of the synchronization separation circuit 12 are input through the input terminal 29 and are input to the phase locked loop (P
LL) 26. Inside the PLL2a, a pulse train with a frequency 115 times the horizontal synchronizing frequency fH is created from the input horizontal synchronizing signal, and this Norms train is further divided into channels to sample the frequency of (57, 5) and IH.・
The (RY) signal and (B-Y) signal input from the pulse train input terminal 26 are each sampled by the sampling pulse train.

However, sampling is performed for odd-numbered lines of the video signal at the rising edge of the sampling pulse, and for even-numbered lines, sampling is performed at the falling edge of the sampling pulse. It is input from the input terminal 26 in FIG. 3 (R-
Y) signal or (B-Y) signal as shown in Figure 4a.
Each fH has a strong spectrum. When the signal of a is sampled at (s7,5) fH, the aliased components are interleaved between the original spectra having strong spectral peaks exactly at every fH, as shown in FIG. In other words, high-frequency components are sampled (sub-Nyquist).
(sampling), it is possible to compress the band by folding back to the lower frequency side.

The outputs of the interleaving circuits 8 and 9 are processed by low pass filters (LPFs) 10 and 11, respectively, so that the horizontal frequency component in the three-dimensional spatial frequency of the video signal is approximately 450K.
The signal is band-limited at Hz, resulting in a band-compressed signal of the form shown in FIG. 4C.

Now, after sampling, the high-frequency components are folded back to the low-frequency side and frequency interleaving is performed, and then the horizontally band-limited (R-Y) signal and (B-Y) signal.
The signals each reach a quadrature two-phase modulation circuit 14. By the way, the horizontal synchronization signal and the equalization pulse train are
From a signal with a frequency of 0-fH, four signals with a frequency of 40·fH, each having a phase difference of 90 degrees, are created.

In the first field, the carrier wave output from the PLL circuit 13 has a frequency of 40·fH, and its phase advances by e o O for each line. In the second field, the carrier wave output from the PLL circuit has a frequency of 4o-fH, and the phase is delayed by 90'' for each line.In the quadrature two-phase modulation circuit 14, the phase is shifted by 2 yields The horizontal band-limited (RY) signal and (B-Y) signal are each quadrature-two-phase modulated by carrier waves having opposite polarities, and the modulated outputs reach an adder 17.

By the way, the carrier wave which is the output of the PLL 13 enters the burst gate 16 and is supplied to the adder 17 only for a period defined by a timing signal delayed by a certain period of time from the horizontal synchronization signal which is the output of the synchronization separation circuit 12. The output of the adder 17 is input to the adder 18, added to the output of the HPF 5, and input to the recording amplifier 19. The recording signal output from the recording amplifier 19 is recorded on the magnetic tape by the magnetic head. The signals recorded on this magnetic tape are
For example, it is expressed as shown in FIG.

In this embodiment, interleaving is performed by sampling, but it can also be performed using a multiplier.

Further, during reproduction, the high frequency components of the two color difference signals which are separated from the luminance signal and demodulated are restored to form a reproduced signal.

Effects of the Invention As detailed above, in the present invention, the frequency band of the color signal to be recorded is approximately twice as wide with a simple circuit configuration, so that the great effect is that high-quality color video signals can be easily recorded. has.

Furthermore, high-density recording without guard bands is possible despite frequency interleaving due to line offset.

2 is a block diagram showing one embodiment of the brifilter, FIG. 3 is a block diagram showing one embodiment of the interleaving circuit, and FIG. 4 is a frequency spectrum diagram illustrating the process of band compression by interleaving. FIG. 5 is a frequency spectrum diagram showing the frequency spectrum of the recording signal.

6.7... Buri filter, 8.9... Interleave circuit, 10.11... Low pass filter, 14... Quadrature two-phase modulation circuit.

Claims (6)

[Claims] (1) A frequency modulation circuit that frequency modulates a luminance signal;
two band compression circuits that band-compress two color difference signals by frequency interleaving and band limiting, respectively, and convert them into two frequency interleaved color difference signals; line is (360×N) degrees, increasing by 90 degrees for each line, and in the second field, the phase of the first subcarrier is changed to (360×N+9)
0) degrees and decreases by 90 degrees for each line, and in the first field of the (M+1)th frame, the first
The first line is (360×N-90
) degrees, and in the second field, the phase of the first subcarrier is set to (360×N+180) degrees, and decreases by 90 degrees every line, and in the (M+2)th frame. In the first field of , the first line shows the phase of the first subcarrier (360
×N-180) degrees, increasing by 90 degrees for each line, and in the second field, the phase of the first subcarrier is (360 × N + 270) degrees for the first line, decreasing by 90 degrees for each line. (M+3) In the first field of the frame, the first
The first line is (360×N-27
0) degrees and increases by 90 degrees for each line, and in the second field, the phase of the first subcarrier is changed every 4 frames so that the first line is (360 × N) degrees and decreases by 90 degrees for each line. a circuit that generates a first subcarrier whose phase changes to , and a second subcarrier whose phase is 180 degrees ahead of the first subcarrier; A quadrature two-phase modulator that performs phase modulation, an addition circuit that adds the output of the quadrature two-phase modulator to a frequency-modulated luminance signal, and a recording amplifier that converts the output of the addition circuit into a recording signal. Characteristic color video signal recording device. (2) Equipped with a band compression circuit that performs sub-Nyquist sampling and frequency interleaving of two color difference signals with a phase shift of 180 degrees for each line and a sampling pulse whose phase is reset to 0 degrees every two fields. The color video signal recording device according to claim 1, characterized in that: (3) Frequency modulate the volatile signal, and convert the two color difference signals into two color difference signals frequency interleaved by band compression by frequency interleaving and band limiting, and set N to an arbitrary integer to
In the first field of the frame, the phase of the first subcarrier is (360 x N) degrees for the first line and 9 degrees for each line.
It increases by 0 degrees, and in the second field, the first
The subcarrier phase of the first line is (360×N+90
) degrees and decreases by 90 degrees for each line, and in the first field of the second frame, the phase of the first subcarrier is (360 x N-90) degrees for the first line and decreases by 90 degrees for each line. In the second field, the phase of the first subcarrier increases as the first line becomes (360
×N+180) degrees, decreasing by 90 degrees for each line, and in the first field of the third frame, the phase of the first subcarrier is (360×N-180) degrees, decreasing by 90 degrees for each line In the second field, the phase of the first subcarrier is
In the first field of the fourth frame, the phase of the first subcarrier is (360 x N-270) degrees and decreases by 90 degrees line by line. The phase of the first subcarrier increases by 90 degrees, and in the second field, the phase of the first subcarrier is
0 x N) degrees, decreasing by 90 degrees for each line.
The two frequency interleaved color difference signals are quadrature-two-phase modulated by a first subcarrier whose phase changes every frame and a second subcarrier whose phase is 180 degrees ahead of the first subcarrier. and adding the frequency-modulated luminance signal and recording it on a magnetic recording medium. (4) The frequency interleaving of the two color difference signals is performed by sub-Nyquist sampling using a sampling pulse whose phase is shifted by 180 degrees for each line and whose phase is reset to 0 degrees every two fields. 4. The color video signal recording method according to claim 3. (5) While frequency modulating the luminance signal, converting the two color difference signals into two color difference signals frequency interleaved by band compression by frequency interleaving and band limiting, and in the first field of each field, the first sub The phase of the carrier wave increases by 90 degrees line by line, and in the second field, the phase of the first subcarrier wave increases by 90 degrees line by line, and N is an arbitrary integer. In the first field of the frame, the difference between the phase of the first subcarrier and the first subcarrier of the adjacent track is 0 degrees for the first line and increases by 180 degrees for each line, and in the second field. The difference between the phase of the first subcarrier and the phase of the first subcarrier of the adjacent track is 180 degrees for the first line and increases by 180 degrees for each line. The difference between the phase of one subcarrier and the first subcarrier of the adjacent track is 180 degrees for the first line and increases by 180 degrees for each line, and in the second field, the phase of the first subcarrier is 180 degrees. and a first subcarrier whose phase changes every two frames such that the phase difference between the first subcarriers of adjacent tracks is 0 degrees for the first line and increases by 180 degrees for each line;
A second subcarrier whose phase is 180 degrees ahead of the first subcarrier.
A method for recording a color video signal, characterized in that the two frequency-interleaved color difference signals are quadrature-two-phase modulated by a subcarrier wave of the subcarrier, and the resultant signal is added to the frequency-modulated luminance signal and recorded on a magnetic recording medium. (6) The frequency interleaving of the two color difference signals is performed by sub-Nyquist sampling using a sampling pulse whose phase is shifted by 180 degrees for each line and whose phase is reset to 0 degrees every two fields. 6. The color video signal recording method according to claim 5.