JPS628680A - Recording and reproducing device for video signal - Google Patents

Abstract

PURPOSE:To perform steady and stable synchronizing separation at a reproducing time by generating the identification timing of a horizontal synchronizing signal based upon a pilot signal recorded simultaneously with a video signal. CONSTITUTION:With counting a clock pulse by an H counter 4 setting a timing detected by a frame pulse detector 2 from an input MUSE signal as reference, an obtained HD frequency becomes the pilot signal by a frequency multiplying circuit 7. By overlapping, by an adder circuit 11, the pilot signal on an MUSE signal FM-demodulated by an FM modulator 9, it is recorded on a magnetic tape 14 by a head 13. The MUSE signal is obtained by a reproducing head 15, a reproducing amplifier 16, a high-pass filter 17 and an FM demodulator 18, and the pilot signal is separated by a band-pass filter 20 and based upon an HD detected at an HD separation circuit 23, the signal, with being time base corrected at a time base corrector 24, is outputted as the MUSE signal.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a video signal recording and reproducing device.

Conventional technology As a high-definition television transmission method suitable for satellite broadcasting, MUSE (Multple Sub-N
yquistSampling Encoding)
A method has been proposed.

This is expected to be a method that will enable high-definition television broadcasting using the 27 MHz bandwidth of one channel of a 12 GHz band broadcasting satellite. The feature of this method is that multiple subsamples are combined with motion compensation to achieve significant band compression. The signal format is a color signal that is compressed on the time axis.
TCI (Time Comprehensive) multiplexed on the luminance signal
sIIed Integration) format, and the horizontal synchronization is a positive synchronization signal. The part indicated by HD in FIG. 2a is the waveform, and the details are shown in FIG. In order to separate the synchronization from this signal, the following methods, which are different from those used in conventional television, are used.

In addition to the horizontal synchronization signal, a frame synchronization signal consisting of a specific bit pattern is inserted into the MUSE signal. This frame synchronization signal is detected, and based on this, a horizontal synchronization signal detection timing is created by dividing the system clock, and when the waveform shown in Figure 2 is detected at the corresponding timing, this is used as the horizontal synchronization signal. be.

However, such a synchronization detection method is unsuitable for video tape recorders (VTRs) that are prone to skew and jitter.

That is, if there is a time axis fluctuation, correct horizontal synchronization detection timing cannot be obtained, and synchronization must be separated only by detecting the synchronization waveform. However, the waveform shown in FIG. 2 has a high probability of appearing in the video signal portion, and is not suitable as a synchronization waveform in a system where the time axis fluctuates greatly.

Therefore, when recording a MUSE signal on a VTR, a negative polarity synchronization signal similar to that of a conventional VTR is added as a synchronization signal.

Problems to be Solved by the Invention As mentioned above, the MUSE signal waveform as described above is inappropriate as a synchronizing signal for a VTR.

Furthermore, in order to add a negative synchronization signal, it is necessary to delete part of the original signal or compress the time axis to free up space for the new synchronization signal. In the former case, some information will be lost, and in the latter case, the highest frequency will increase, neither of which is desirable.

The present invention solves the above-mentioned problems and provides a video signal recording and reproducing apparatus which can record the MUSE signal waveform as it is and can perform reliable and stable synchronization separation during reproduction.

Means for Solving the Problems In order to solve the above problems, the present invention records a frequency modulated video signal and a pilot signal synchronized with a horizontal synchronizing signal included in the video signal at the same location on the medium. During reproduction, a timing signal for identifying the horizontal synchronizing signal is created based on the reproduced pilot signal, and the horizontal synchronizing signal is identified at this timing.

Effects of the present invention With the above-described configuration, the horizontal synchronization signal included in the video signal is positive polarity synchronization, and even if skew or jitter occurs in the reproduced signal, the horizontal synchronization signal can be identified based on the pilot signal recorded at the same time. To create timing, synchronization separation can be performed without error, and T operates based on this.
A normal reproduction signal can be obtained by BC.

Embodiment FIG. 1 shows an embodiment of the present invention. 1 is an A/D converter,
2 is a frame pulse detection circuit, 3 is a clock generation circuit,
4 is a counter that counts clock pulses to generate the timing of the H period; 6 is f() which compares the phase of the HD generated by the counter 4 and the HD of the input signal, and feeds back the phase error to the clock generation circuit 3; A D phase comparator circuit. 6 is a circuit that generates V or field timing, 7 is a circuit that multiplies the frequency of I (D), 8 is a V synchronization insertion circuit, and 9 is a circuit that FM modulates the input MUSE signal. 1o is a high-pass filter, 11 is an adder circuit, 12 is a recording amplifier, 13 is a recording head, 14 is a magnetic tape, 16 is a reproduction head, 16 is a reproduction amplifier,
1 is a high-pass filter, 18 is an FM demodulator, 19 is a V synchronization signal separation circuit, 2o is a bandpass filter, 21 is a waveform shaping circuit, 22 is a counter, 23 is an HD separation circuit, 24 is a time base collector (TBC) It is. The present embodiment will be explained based on a VTR that is of a rotating two-head type and records one field on one track. The input MUSE signal is A/D converted by the A/D converter 1 at the timing of a clock pulse generated by the clock generation circuit 3. Since the frame synchronization signal of the MUSE signal has the shape shown in FIG. 3, it can be detected by digital calculation. Therefore, a frame pulse is detected by the frame pulse detection circuit 2 from the A/D converted signal. Based on the timing of this frame pulse, clock pulses at a transmission rate of 16.2 MHz are counted by the H counter 4 to obtain the HD timing. Obtained HD
The HD phase comparator circuit 6 compares the timing with the timing when the transmitted MUSE signal is A/D converted to obtain the HD waveform (in Figure 2), and the phase error is fed back to the clock generation circuit 3, which generates a clock. The clock generated by the circuit is used as a phase clock for the transmission signal. The HD frequency obtained by the H counter 4 is multiplied by 10.5 by a frequency multiplier 7 to become a pilot signal. (2) The timing generation circuit 6 generates V timing from the 7 frame pulses and HD, resets it at the first HD of (2), and furthermore, slightly before that, the V synchronization insertion circuit 8 inserts a negative V synchronization signal into the MUSE signal. FIG. 4a shows the MUSE signal, and FIG. 4b shows the pilot signal synchronized with it. Figure 6a shows the MUSE signal with the V synchronization signal inserted, and b shows the pi. ; indicates a signal.

As described above, the output of the multiplier circuit 7 is a signal having a frequency 10.5 times the H frequency, which is reset at the first H timing of the field and is phase-locked to H thereafter. This signal is sent to the FM by the adder circuit 11 and by the FM modulator 9.
It is superimposed on the modulated MUSE signal passed through the high-pass filter 1o. This high-pass filter has a sufficient attenuation rate in the frequency domain of the pilot signal.

The signal obtained above is amplified by a recording amplifier 12 and recorded on a magnetic tape 14 by a recording head 13.

During playback, the playback head 16. The regenerative amplifier 16° high-pass filter 1 and the FMi adjuster 18 generate the M shown in FIG. 6a.
A USE signal is obtained. (2) The synchronization separation circuit 19 separates the V synchronization signal from this signal.

On the other hand, the output of the regenerative amplifier 1e passes through a bandpass filter 20, and the pilot signal is separated.

Even if jitter occurs between the reproduced MUSE signal and the pilot signal, the phase relationship shown in FIG. 4a and b is always maintained. The pilot signal obtained as the output of the bandpass filter 2o is converted into a pulse by the waveform shaping circuit 21 and input to the counter 22. The counter 22 is reset by the synchronously separated V synchronization signal and counts the pulses obtained from the pilot signal. The color/receiver 22 outputs the timing at which the MUSE synchronization signal should exist, and operates the HD separation circuit 23 only during that period.
Waveforms similar to the USE synchronization waveform can be excluded, and the true MUSE synchronization waveform can be stably and reliably separated.

6A is a reproduced MUSE signal, b is a reproduced pilot signal, C is a signal obtained by waveform shaping of b, and d is an output of the counter 22 and a gate signal of the HD separation circuit. Note: The synchronization signal is added to reliably detect the skew that occurs in the VTR, and becomes unnecessary if the non-recorded part of the V blanking part of the pilot signal is actively used for skew detection. .

Based on the HD detected by the HD separation circuit 23, the time base collector (TBC) 24 corrects the time axis and outputs the MUSE.
Output as a signal. The TBC may be either analog or digital.

Although omitted in the figure, it goes without saying that a write clock generation circuit for the TBC and a read clock generation circuit are required.

The write clock is created based on the HD output from the HD separation circuit 23, and the read clock is created by a fixed oscillator. Here, the write clock can also be created by multiplying the pilot signal.

In the above embodiment, one track records one field.
I explained about TR, but MU! 3 to record the signal V
Since TR requires approximately twice the bandwidth of NTSC signals,
The rotation of the head drum may be doubled, or the video signal may be divided into two channels to perform two-track parallel recording. In these cases, it is necessary to insert a synchronization signal at an appropriate timing near the scanning start point of each video track in addition to the V synchronization signal of the above embodiment.

In addition, although relatively low frequencies of 1o and 5fH were selected as the pilot signals in the above, it is not limited to this value. If it is acceptable in terms of the influence on image quality, a frequency of about 1 oofH is possible, depending on the relationship with the FM carrier wave, and the higher the frequency is selected, the better the gate precision of HD separation will be.

In the above example, since a continuous wave was used as the pilot signal, it would be superimposed on the video signal over the entire screen, potentially increasing the influence on the screen. Therefore, in order to reduce such an influence, it is sufficient to superimpose a pilot signal only on a part of the 1H period. A time chart in this case is shown in FIG. Figure 7a is the MUSE signal, b
, a are two examples of pilot signals. In the first embodiment, in order to reduce the adverse effect on the screen, the frequency of the pilot signal was set to 1o, s fHc (horizontal scanning frequency) in order to interleave with the horizontal scanning frequency.
In this case, the frequency of the pilot signal itself should be set to 3A.
There is little need to offset fH.

The difference between b and C is that C has a narrower band, and the band of the bandpass filter through which the pilot signal passes can be narrowed, so that a good S/N ratio of the pilot signal can be obtained.

The pilot signal of the present invention can also serve as a so-called tracking pilot signal.

There are various methods of tracking pilot t.
Basically, each track records a pilot signal with a frequency that is different from adjacent tracks and has a certain relationship.
During reproduction, tracking information is obtained from the reproduced pilot signals of the current track and adjacent tracks. The pilot signal of the present invention is also not only 10.6 fH, but also 6.5 fH, 7,6 fH, 10,5 fH.
, 9.5fH are sequentially and cyclically recorded, tracking is possible using a well-known technique for 8mm video (Archer: "8mm Video" TV Society Journal Vol. 1.39/&, 4.P334).

However, in this case, it is necessary to change the count number of the color/return 22 for each track.

In addition, regarding the accuracy of the gate signal for HD separation timing, in the above example, the color/return 22 clock is the pilot signal itself, and high accuracy cannot be expected, but it is well known that higher-speed clock pulses, monostable multipipe rake, etc. It is easy to generate highly accurate gate signals using this technique.

Methods for superimposing the pilot signal and FM video signal include simple frequency separation as described above, as well as deep recording of the pilot signal using separate heads with different azimuths for the pilot signal and FM video signal. , video signals can also be recorded on the surface layer. In this case, the pilot signal and the FM video signal can be separated with even higher accuracy.

Effects of the Invention According to the present invention, it is possible to realize a video signal recording and reproducing apparatus that can stably and reliably perform horizontal synchronization separation during playback even when FM recording is performed with positive polarity synchronization without time axis scanning of the MUSE signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
The figure is a waveform diagram showing the horizontal synchronization waveform of the MUSE signal, FIG. 3 is a waveform diagram showing the frame pulse of the MUSE signal, and FIG. 4 is a waveform diagram showing the recording waveform (H rate) of the first embodiment of the present invention. , FIG. 5 is a waveform diagram showing the recording waveform of the V blanking section of the first embodiment of the present invention, and FIG. 6 is a waveform diagram for explaining the operation during reproduction of the first embodiment of the present invention. FIG. 7 is a waveform diagram showing recording waveforms in the second embodiment of the present invention. 1...A/Df conversion! , 2... Frame pulse detection circuit, 3... Clock generation circuit, 4...
...Counter, 6...f (D phase comparison circuit,
6...■Timing generation circuit, 7...
Multiplication circuit, 8... ■Synchronization insertion circuit, 9...
...FM modulation circuit, 10...high-pass filter,
11... Adding circuit, 1゛2... Recording amplifier, 13... Recording head, 14...
Magnetic tape, 15... Playback head, 16...
... Regenerative amplifier, 17 ... High-pass filter, 1
8...FM demodulator, 19...V synchronization signal separation circuit, 20...Band filter, 21...
... Waveform shaping circuit, 22 ... Counter, 23.
...HD separation circuit, 24...Time base collector. Name of agent: Patent attorney Toshio Nakao? 1 or 1 person 1
Mizumoto Figure 2 D (b) Figure 3 Figure 4 Bay Figure 5

Claims (3)

[Claims] (1) A negative synchronization signal is inserted into the video signal near the start point of scanning by the rotating head of the video track on the tape, and it is reset by the horizontal synchronization signal immediately after that, and from then on, the horizontal synchronization signal of the recorded video signal is applied to the entire track. means for creating a first phase-synchronized signal; means for FM modulating a video signal to create a second signal; and means for recording and reproducing the first and second signals in a superimposed manner on a recording medium. , means for separating first and second signals from the reproduced signal, and means for FM demodulating the second signal to obtain a reproduced video signal;
The device comprises means for separating negative polarity synchronization from the video signal, and means for separating a positive polarity horizontal synchronization signal included in the reproduced video signal using the separated negative polarity synchronization and the first signal as a reference. A video signal recording and reproducing device characterized in that a time pace corrector is operated using a horizontal synchronization signal as a time axis reference signal to obtain a time axis corrected output video signal. (2) The video signal recording and reproducing apparatus according to claim 1, wherein the first signal is a continuous wave for each track. (3) The video signal recording and reproducing apparatus according to claim 1, wherein the first signal is a discontinuous wave within one track.