JPS602836B2 - SECAM color television signal recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a color television signal (
This relates to a recording and reproducing method for SECAM signals), and is configured to reduce the influence of crosstalk from the adjacent green track, which will be described later, and to perform high-density recording and reproducing.

Recently, for high-density recording, a helical scan type magnetic line drawing reproduction machine (VTR) using the azimuth effect has been devised.

This is done by making the gap directions of the magnetic heads for recording and reproducing adjacent recording tracks different from each other, so that even if parts of adjacent tracks are scanned at the same time during reproduction, no output is obtained from the adjacent tracks due to the azimuth effect. This is what I did.

On the other hand, in a simple VTR that records and plays back a composite color television signal, the composite color television signal to be recorded as shown in FIG. Then, the chrominance signal C is frequency-converted to a low frequency range (approximately 600 to 70 mm), and the FM luminance signal Y is converted to C' as shown in the opening of Figure 1. '(FM)
I recorded it as a child's tatami mat.

Therefore, FM with high recording frequency (short recording wavelength)
The azimuth effect of the luminance signal can sufficiently eliminate the influence of crosstalk from adjacent tracks, but the chrominance signal converted to low frequency has a small azimuth angle (10 degrees).
It cannot be expected that sufficient removal of crosstalk due to the azimuth effect can be expected in the cultivation process.

Therefore, in the NTSC system, Tsubaki Europe 50-427
As disclosed in the above issue, the low-converted chrominance signals are frequency-interleaved and recorded between adjacent recording tracks, and during playback, the low-frequency converted chrominance signals from the adjacent recording tracks are removed by a rectangular filter. ing.

In the SECAM signal, the above-mentioned <
It is difficult to use a removal method using a rectangular filter.
That is, the SECAM signal has B-Y whose center frequency is 4.29 MHz in the Takagi frequency part of the luminance signal Y, and 4.40 MHz.
Since the R-Y chroma FM modulated wave signal of Enthronement Z is folded as a line-sequential signal to form a composite wave signal, the above-mentioned method using a rectangular filter cannot obtain the correlation of mutual carrier waves between adjacent tracks. is extremely difficult.

In the present invention, the luminance signal component of the SECAM signal is FM-modulated to remove crosstalk from adjacent recording tracks using the azimuth effect of the magnetic head, and the chrominance signal is
By converting the frequency to a low frequency band so that the frequency band is different between adjacent recording tracks, the crosstalk from the adjacent recording tracks is removed using a three-wavelength filter during playback. With reference to this, an example thereof will be given and explained.

The R-Y signal of the extension sequential signal of the chrominance signal in the peak MHz to small Hz band of the SECAM signal has a center frequency of 4.4 Hz and a maximum frequency deviation of 135 MHz and -50 Hz, and B - Each of the Y signals is 4.2 Noriyama z, 150
0 KHz, 135 Saramachi z.

Therefore, the maximum frequency deviation is 85 Hz, and this FM
When a chrominance signal is simply heterodyned and frequency-converted to a low frequency band and recorded, the chrominance signal band width may be about IMHz. Therefore, one configuration for changing the frequency band of the chrominance signal between adjacent tracks so that they can be separated during playback is as shown in FIG.
z, the lower and upper limits of the chrominance signal band C2 of the second recording channel track are approximately IMHz and 2M, respectively.
It is sufficient to set it to Hz.

Note that f3 and f4' are the lower limit and upper limit frequencies of the FM luminance signal, and are cape Hz and arc Hz, respectively. Next, with reference to FIG. 3, a specific configuration of a recording/reproducing system at a stage prior to the present invention will be explained. In Figure 3, 1 is the SE to be recorded.
This is a CAM signal input terminal, and the SECAM signal applied to this input terminal 1 is extracted by the low-pass filter 2 of the fox mz, and only the luminance signal component is extracted by the FM modulator 3. After being modulated into FM waves, high-pass filter 4
Accordingly, the signal is applied to the adder 5 as a signal in a frequency band of 2 MHz or more.

On the other hand, an FM chroma signal is separated from a portion of the SECAM signal applied to the input terminal 1 by a bandpass filter 6 of about 4.3±0.7M, and applied to a balanced modulator 7. 8,
9 is about 4. Masu MHz and about 5. This is a crystal oscillator that generates a frequency of around M. Both outputs are applied to the switching circuit 101, and the signals related to the head switching signal applied from the terminal 11 are used to switch the recording channel according to the switching of the recording channel. Chemisaki Z and 5. Breast female Z signals are output alternately.

From this output, C, , C2 chrominance signals are obtained as the output of the balance modulator 7 in accordance with switching of the recording channel, and the C, C,
(0 to IM ratio) and C2 (1 to 2 MHz) chrominance signal components are extracted, respectively, and the switching circuit 14
According to the signal related to the head switching signal applied from the terminal 15, C and C2 chrominance signals are alternately extracted in response to switching of recording channels. This extracted low frequency converted chrominance signal C, or C2
is added to the FM modulated luminance signal Y (FM) by the adder 5, and is applied to the first recording channel head 16 and the second recording channel head 16' as a signal shown in FIG. recorded.

During reproduction, the signals of the first and second recording channels alternately reproduced by the heads 16 and 16' are applied to the Takagi filter 17, the reduction filter 18, and the Obishiro filter 19, respectively. The FM luminance signal component separated by the filter 17 is demodulated into the original luminance signal by a limiter 20 , an FM demodulator 21 , and a low-pass filter 22 , and is applied to an adder 23 .

On the other hand, the low-pass converted chrominance signals C, , C2 separated by the former low-pass filter 18 and the bandpass filter 19
is applied to the switching circuit 24, selectively extracted in response to head switching by a signal related to the head conversion signal applied to the terminal 25, and applied to the next balance modulator 26. In this equilibrium modulator 26, 4. A chrominance signal is balanced-modulated by the signals of Chemisaki z and 5.8 Komachi z, and is restored to its original frequency as the output of Obishiro filter 27. This restored chrominance signal is added to the demodulated luminance signal component in the adder 23, and is outputted to the output terminal 28 as a restored SECAM signal.

According to the above configuration, since the low frequency converted chrominance signal is recorded with different frequency bands between adjacent recording tracks, even if crosstalk from adjacent recording tracks occurs during playback, it can be reduced. wave filter 18 and obijo filter 1
9, it can be easily removed.

Next, a configuration in which a more effective means is added when recording in different frequency bands as described above will be explained with reference to FIG.

The difference between FIG. 4 and FIG. 3 is that a down-down ratio 30 with a down-down ratio of 1/2 is provided between the bandpass filter 6 and the balanced modulator 7, and a down-down ratio 30 is provided between the switching circuit 24 and the balanced modulator 26. A multiplication circuit 31 with a multiplication ratio of 2 is inserted, and the oscillation frequencies of oscillators 8 and 9 are each set to 1.
/2 2.42MHz and 2.9 Mizukawa z.

In this way, by using the downshifter 30 when converting the chrominance signal frequency to a lower frequency range, the following effects can be obtained. When a chrominance signal with a wave number deviation of 85 Hz as shown in Figure 5A is converted to a low frequency by only balanced modulation as in the configuration shown in Figure 3, it becomes as shown in Figure 5A. The maximum frequency range is converted as 85 Hz, but when balanced modulation is performed after dividing the frequency by 1/2 by a stepdown device as in the configuration shown in Figure 4, the maximum frequency is changed as shown in Figure 6 C. The frequency deviation becomes 1/2, 42, and the transmission band is reduced accordingly, using the limited transmission band,
This is convenient in a system that transmits data using different frequency bands.

-Also, if the center frequency fc is kept constant, the lower limit frequency fcL of the maximum frequency deviation will be increased by 850/2 KHz, and the cross stroke due to the azimuth effect can be removed and reduced by that much.

Also, as shown in Figure 5 2, the center frequency is fc'(fc'
>fc), and can be made to obtain a better azimuth effect. It should be noted that the larger the frequency division ratio of the downshifter 30, the more the band width will be compressed, and it is clear that during reproduction, the frequency division ratio is multiplied by the downshifter 31. It is possible to use only a dropout device without using a balance modulator.

Furthermore, FIG. 6 shows an embodiment of the present invention in which effective means are added.

Figure 6 shows the recording pattern on the magnetic tape.
, B are recording trajectories by the magnetic heads 11 and 11', respectively, and signals recorded in adjacent tracks correspondingly are at approximately the same horizontal scanning position (in the case of the embodiment, 1.5 horizontal scanning lines). The same type of chrominance signals, that is, R-Y, B-Y and 8-Y are arranged adjacent to each other.

In this way, by recording the same type of chrominance signals in a layered manner at approximately the same horizontal scanning position, the correlation between the two adjacent signals becomes extremely high, as shown in Figure 7. Channel 1 R recorded on track A
- When the center fc of the frequency band of the Y signal (FM modulated wave) moves to the Takagi side according to the transmission information, the R-Y signal of channel 2 recorded on the adjacent track B also increases. Since the signal is moved toward the frequency side, crosstalk between both tracks is reduced.

As described above, according to the present invention, it is possible to record and reproduce SECAM signals by reducing and eliminating crosstalk from adjacent tracks and by effectively using a limited band, so that high-density recording can be achieved. It is something.

Further, in the present invention, when converting the chrominance signal of the SECAM color television signal to a low frequency,
The maximum frequency deviation of the chrominance signal converted to reduction is 1/2 because the duration is at least 1/2 or more.
As a result, the subtympanic limit frequency of the recorded low-frequency converted chrominance signal becomes higher, and crosstalk can be eliminated and reduced due to the azimuth effect of the magnetic head, reducing the band of the chrominance signal between adjacent tracks. There is no need to make them completely different, and the limited recording frequency band can be used effectively. Furthermore, in the present invention, since the same type of chrominance signals are arranged next to each other between adjacent tracks, the correlation between these adjacent signals is high, and crosstalk between both tracks is reduced. Brief Description of the Drawings Fig. 1 is a spectrum diagram for explaining the low frequency conversion recording method, Fig. 2 is a spectrum diagram for explaining the outline of the present invention, and Fig. 3 is a spectrum diagram for explaining the outline of the present invention. A block diagram showing an overview,
FIG. 4 is a block diagram showing the main parts of the embodiment of the present invention, and FIG.
6 is an explanatory diagram of the same operation, FIG. 6 is a diagram showing a recording pattern of an embodiment of the present invention, and FIG. 7 is an explanatory diagram of the same operation.

1... Input terminal, 2, 12... Low-pass filter, 3... FM modulator, 4... High-pass filter, 5 ... Adder, 6, 13 ... Bandpass filter,
7... Balance modulator, 8, 9... Oscillator, 10,
14...・Switching circuit, 16, 16'...
...magnetic head.

Fin diagram Figure 2 Figure 3 Figure 5 *Figure 4 Figure 6 Tsutomu Figure 7

Claims (1)

[Claims] 1. Separating a SECAM color television signal to be recorded into a luminance signal component and a chrominance signal component, angularly modulating the luminance signal component on the high frequency side, and dividing the chrominance signal into at least two frequencies; Furthermore, the frequency is converted to a lower frequency so that adjacent tracks have different frequency bands and is superimposed on the angle-modulated luminance signal component. A recording method for SECAM color television signals, which is characterized in that color signals of the same type are recorded on a recording medium so as to be lined up.