JPS6370690A - Picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve an SN ratio, to eliminate the need for a time-base compressing and expanding process and to reduce the cost of a device by imposing FM modulation on a video signal which has a positive-polarity synchronizing signal and recording a horizontal burst signal and a pilot signal on a frequency multiplex basis together with the FM-modulated video signal. CONSTITUTION:An MUSE signal from an input terminal 1 is applied to an FM modulator 2 and a synchronous separating circuit 3, which detects the positive-polarity synchronizing signal and separates the horizontal synchronizing signal. This signal is applied to a modulator 2 and also applied to a burst signal generator 4 to generates a horizontal burst signal. The level variation of this horizontal burst signal is matched with the gradient of the positive-polarity synchronizing signal of the MUSE signal. The FM signal from the modulator 2, on the other hand, is sent to an adder 7 through an HPF 5 and frequency-multiplexed by the adder 7 with the horizontal burst signal and the pilot signal from a pilot generator 6. This multiplex signal is applied to a head 9 through a recording amplifier 8 and recorded on a tape 10. Consequently, the signals are recorded with a large frequency shift and the SN ratio is improved. Further, no time-base compression is performed, so any expanding process is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording and reproducing apparatus for recording a video signal having a positive synchronization signal.

[Prior Art] An example of a video signal having a positive synchronization signal is a MUSE signal obtained by band-compressing a high-definition television signal.

Conventionally, when recording a MUSE signal on a recording/playback device such as a video tape recorder, the MUSE signal shown in FIG. 6(a) is compressed on the time axis in units of one horizontal scanning period (IH) and A negative polarity synchronous signal (hereinafter referred to as negative polarity synchronous signal) in which synchronization is separated by amplitude discrimination is applied to the vacant part.
A burst signal for jitter detection was inserted as shown in FIG. 6(b). If a video signal having a positive polarity synchronization signal is sick, the positive polarity synchronization signal cannot be separated, so a negative polarity synchronization signal is inserted so that the synchronization can be separated even when there is jitter.

The above two matters are described and disclosed in the television technical report VR70-4, ``Study of Analog Segment Recording in Home MUSE VTR''.

In Figure 6, (C), (Y), (S) are
Indicates each color signal, m degree signal, and positive synchronization signal, (C
o), (Yo), and (So) indicate time-axis compressed color signals, luminance signals, and positive synchronization signals, respectively. The signal shown in FIG. 6(b) after the above signal processing is MU
It is called SE signal A.

This MUSE signal A signal bar is modulated and recorded on a tape, and upon reproduction, the reproduced MUSE signal A signal bar pole synchronization signal is separated. A/D conversion is performed by clamping the MUSE signal using this negative synchronization signal, and at the same time, a burst signal for jitter detection is extracted using the negative synchronization signal. A write clock is created and jitter is corrected using a digital time base corrector for chic removal.

For this purpose, conventionally, a negative synchronization signal and a burst signal have been inserted as shown in FIG. 6(b). FIG. 6(C) shows frequency allocation when this negative polarity synchronization signal is modulated with the inserted MUSE signal A signal bar.

In the figure, (fS), (fB), and (fW) indicate the FM carrier frequencies of the tip of the MUSE signal A signal bar, the black level, and the white level, respectively. Normally, the ratio of the negative synchronization signal level to the video level is 3:7, so the frequency deviations of the FM modulated MUSE signal A signal bar synchronization signal and the video portion are 3:7, i.e. (fR-fS): (fW-f
B) =3:7.

[Problems to be Solved by the Invention] In the conventional recording/playback device which records a video signal having a positive polarity synchronization signal as described in 2, among the FM frequency deviations (△f), That 3/lO must be assigned to the negative sync signal, and MUS
The frequency deviation of the E signal A signal bar O signal part is:
This is 7/10 of the above FM frequency deviation (Δf). Once upon a time, the above FM frequency deviation (△f
) is assigned to the video signal part, the playback M
The S/N of USE signal A is 3 dB inferior, and the same S/N
/N requires a head with a 3 dB higher reproduction output, for example.

Also, to insert a negative sync signal and a burst signal,
A video signal having a positive synchronization signal is time-axis compressed, and the bandwidth of the video signal increases by the reciprocal of the time-axis compression rate, and the recording bandwidth of the recording/playback device increases accordingly.

Furthermore, signal processing circuits such as an A/D converter and memory are required to time-base compress the MUSE signal and insert a negative synchronization signal and a burst signal, resulting in an expensive recording/playback device. Ta.

This invention was made to solve the above-mentioned problems, and by compressing the time axis of a video signal having a positive synchronization signal, the video signal can be compressed without inserting a negative synchronization signal and a burst signal for jitter detection. It is an object of the present invention to provide a recording/playback device that can easily remove jitter during playback and improve the S/N of a video signal with a simple circuit configuration.

Means for Solving Problem E] The recording and reproducing apparatus according to the present invention generates in a recording system a horizontal burst signal having positive synchronization position information of a video signal having a positive synchronization signal and a pilot signal for jitter detection. and the reproduction system includes means for detecting the position of the positive synchronization signal from the horizontal burst signal and means for generating a write clock for A/D conversion having jitter information of the reproduced video signal from the pilot signal. It is characterized by

[Operation] In the present invention, during reproduction, the positive synchronization position of the video signal is detected from the horizontal burst signal and clamped so that the video signal is accurately A/D converted.

The pilot signal has information on time axis fluctuations during reproduction, and jitter is removed by creating a write clock for A/D conversion that matches the time axis fluctuations of the reproduced video signal from the pilot signal.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 is a block diagram showing the configuration of a recording/playback apparatus according to an embodiment of the present invention. In the same figure, (1) is M
Video input terminal where USE signal is input, (2) is FM
Modulator, (3) is a sync separation circuit that separates a positive sync signal, (4) is a burst signal generator that generates a horizontal burst signal, (5) is an HPF, (6) is a pilot signal generator, (7) is an adder, (8) is a recording amplifier, (SW) is a changeover switch connected to a recording (R) terminal and a reproduction (P) terminal, (9) is a head, and (10) is a tape.

(11) is a regenerative amplifier, (12) is an HPF that removes the horizontal burst signal and pilot signal and passes only the FM signal, (13) is an FM demodulator, (14) is a BPF that extracts the pilot signal, (15) ) is a BPF that extracts the horizontal burst signal, (16) is a zero cross detector that detects the zero cross of the horizontal burst signal, (17) is a differentiation circuit that differentiates the horizontal burst signal, (18) is a comparator, and (19) is a clamp. Pulse generation circuit, (20) is F
This is a clamp circuit that clamps the M-demodulated MUSE signal.

(21) is a digital time base collector.

(22) is an A/D converter, (23) is a write clock circuit that creates a write clock phase-synchronized with the pilot signal, (24) is a digital memory, (26) is a D/A converter, (25) is a beam. The clock circuit (27) is an output terminal for the reproduced MUSE signal.

Next, the operation of the configuration described in - will be explained.

A MUSE signal is input to the input terminal (1). This M.U.
The waveform of the SE signal is shown in FIG. 2(d).

This MUSE signal is applied to an FM modulator (2) and a sync separation circuit (3), which detects whether it is a positive sync signal and separates a horizontal sync signal.

This horizontal synchronization signal is applied to the FM modulator (2) and the MU
The flat portion of the positive synchronization signal of the SE signal is clamped.

The clamped MUSE signal is FM-modulated, and the horizontal synchronization signal is further applied to a burst signal generator (4) to generate a horizontal burst signal with a burst frequency (fHB). FIG. 2(e) shows the waveform of this horizontal burst signal. The zero crossing is M shown in 2nd (d)
It matches the positive synchronization signal of the USE signal.

There are 1125 horizontal scanning lines of the MUSE signal, and the slope of the positive synchronization signal for each line is as shown in FIG. The slope is set at the 607th line. Therefore, the level change of the horizontal burst signal is M
It matches the slope of the positive synchronization signal of the USE signal. In other words, if the slope of the positive synchronization signal is a positive slope changing from low level to high level, the level change of the horizontal burst signal is
In the case of a negative slope, in which the slope of the positive synchronization signal changes from a high level to a low level, the level change of the horizontal burst signal changes from positive to negative.

The horizontal burst signal, which is the output of the burst signal generator (4), is sent to an adder (7). At the same time, the pilot signal generator (6) is connected to the playback side time base collector (2).
A pilot signal having a frequency (fp) obtained by dividing the write clock frequency of the A/D converter (22) in 1) by N7M (N is an integer such that N>M>O) or N7M fWc is generated. FIG. 2(f) shows this pilot signal, and this pilot signal (f) is sent to the adder (7).

On the other hand, the FM signal output from the FM modulator (2) is
F (5), frequency components below the lower first side hand of the FM signal are removed and sent to an adder (7), where they are frequency multiplexed with the horizontal burst signal and pilot signal.

Figure 4(a) shows the HP F of the FM-modulated MUSE signal.
The frequency spectrum at the output of (5) is shown.

In the same figure, (fB) and (fW) are each MU
The FM carrier frequencies of the black level and white level of the SE signal are shown. (Δf) indicates frequency deviation.

FIG. 4(b) shows the frequency spectrum of the frequency multiplexed signal output to the adder (7). (S1) and (S2) indicate the frequency spectra of the horizontal burst signal and pilot signal, respectively. (fHB) indicates the burst frequency of the horizontal burst signal. In this embodiment, the horizontal burst signal is composed of a one-cycle burst signal, and the frequency (fp) of the pilot signal is selected such that fp>fHB in relation to the frequency of the burst signal (fHB). Therefore, the frequency spectra of the horizontal burst signal and the pilot signal are multiplexed so that they do not overlap in frequency with the frequency spectrum of the FM signal. This frequency multiplexed signal is amplified by the recording amplifier (8), and during recording, it passes through the switch (SW) connected to (R) and the head (
9) and recorded on tape (]0)J-.

Next, the operation during playback will be explained.

The frequency multiplexed signal recorded on the tape (] 0 ), h is reproduced by the head (9), and during reproduction, it is sent to the reproduction amplifier (II) via the switch (SW) connected to the terminal (P).
is added to and amplified.

The output of the reproduction amplifier (11) is HP F (12), B
added to P F (+4) and B P F (15).

The frequency multiplexed signal added to HP F (+2) is FM
Only the modulated MUSE signal is extracted and applied to the FM demodulator (13), where the MUSE signal is demodulated.

On the other hand, a horizontal burst signal having the same waveform as shown in the second (e) is extracted from the frequency multiplexed signal added to B P F (15). This horizontal burst signal is applied to a cello-cross detector (16) and a differentiation circuit (17), and the zero-cross point of the horizontal burst signal is detected by the zero-cross detector (16). FIG. 2(g) shows this cello cross signal. In the figure, the black part indicates the amplitude of the reproduced horizontal burst signal has dropped, and due to noise from the tape, the output of the zero cross detector (16) changes from low level to high level due to noise. It shows. This zero cross signal (g) is applied to the clamp pulse generation circuit (19).

On the other hand, the reproduced horizontal burst signal (e) applied to the differentiating circuit (17) is differentiated by this circuit (17).

FIG. 2(h) shows a differential horizontal burst signal. This signal is applied to a comparator (18) which outputs a high level for inputs above a certain voltage value, and a low level for inputs smaller than that.

The output of the comparator (18) is shown in FIG. 2(i).

The output (i) of this comparator (18) is also applied to the clamp pulse generation circuit (19). The above zero-crossing signal (g) has information on the positive synchronization signal position of the MUSE signal (d), while the comparator output (i) has the reproduced horizontal burst signal (
e) includes a zero-crossing point that changes from negative to positive.

The clamp pulse generation circuit (19) first gates the zero cross signal (g) with the comparator output (i) to generate a positive slope positive synchronization signal pulse (j) corresponding to the positive slope positive synchronization signal of the MUSE signal (d). ).

Next, a clamping pulse (k) is created by delaying this pulse (j) so that it coincides with the timing of the high level of the positive polarity synchronization signal with the positive slope of the MUSE signal (d). This clamp pulse (k) is applied to the clamp circuit (20). The clamp circuit (20) includes an FM demodulator (
13) is applied, and a clamping pulse (k) clamps the high level portion of the positive slope stop synchronization signal to a constant voltage every two horizontal periods. This clamped MUSE signal is applied to the A/'D converter (22) of the time base collector (21) and is accurately A/D converted.

On the other hand, B F P (14) extracts a pilot signal of the same frequency as shown in FIG. 2(f) from the frequency multiplexed signal. This pilot signal has time axis variation information of the device and is applied to the write clock circuit (23) of the time base collector (21).

Next, a digital time base collector (
The operation of 21) will be explained.

The MUSE signal, which has been clamped to a predetermined voltage by the clamp circuit (20) as described above, is applied to the A/D converter (22).

On the other hand, the write clock circuit (23) multiplies the input reproduced pilot signal of frequency fp=N/M fWC by N/M to create a write clock of frequency fWC that is phase-synchronized with the pilot signal. The ride clock created from the pilot signal in this way is transmitted to the regenerated MU
It has the same time axis fluctuation as the SE signal.

The MUSE signal applied to the A/D converter (22) is sampled by the write clock, A/D converted, and then written to the digital memory (24). Here,
The write clock has the same time axis fluctuation as the reproduced MUSE signal. Therefore, since the reproduction MUSE signal and the sunblink are performed at a timing that follows the rotation time axis fluctuation, the sunblink of the MUSE signal is performed at the correct timing. The memory (
The reproduced MUSE signal written in 24) is read out using a stable read clock supplied from the read clock circuit (25), is D/A converted by the D/A converter (26), and is returned to the MUSE signal. As a result, a reproduced MUSE signal with a stable time axis can be obtained at the output terminal (27).

Next, another embodiment of the present invention will be described in which the jitter correction effect is enhanced by improving the S/N ratio.

In the above embodiment, the pilot signal is frequency multiplexed on the lower side of the FM signal. In this case, by increasing the recording level of the battlelot signal, the reproduction S/N of the pilot signal can be increased. However, when the recording level of the pilot signal is increased, cross-modulation occurs in the FM signal due to odd-order distortion in the electromagnetic conversion system.

This will be explained with reference to FIG. FIG. 5(a) shows the frequency spectrum of a recording signal when two sinusoidal signals with frequencies (fl) and (fl) are frequency-multiplexed and recorded. (
Fig. 5 shows the frequency spectrum when the frequency multiplexed signal (fl) corresponds to the carrier component of the FM signal, and (fl) corresponds to the pilot signal is recorded on a tape and played back.
Shown in b). When the recording level of the sine wave of frequency (fl) is increased, fl ±
2 fl intermodulation occurs. This intermodulation component (fl±2f2) is F
It is demodulated as (2fl) unnecessary components by the M demodulation process.

The spectrum of this unnecessary component is shown in FIG. 5(c).

In the case of the above embodiment, (fl) corresponds to the frequency of the pilot signal, so it is a fixed frequency. On the other hand (fl)
corresponds to the carrier component of the FM signal, so the frequency changes. However, the unnecessary component generated by the FM demodulation process is fixed at (2fl) regardless of the change in the frequency of (f]).

That is, the frequency component is twice the frequency of the pilot signal or is an unnecessary component. However, the frequency of the pilot signal (
If fp) is chosen so that fH is the horizontal frequency and N is a positive integer, then the frequency of the unnecessary component is 2fPA==ζN
+1=Tsukuda, which has an interleaving relationship with the horizontal synchronous layer wave number (fH), and when viewed on the screen, interference becomes less noticeable.

In this way, if the frequency (fP) of the pilot signal is selected so as to satisfy fP = lN + i - 1,000H, the recording level of the pilot signal can be increased since the interference of unnecessary components can be reduced, and S A reproduced pilot signal with a good S/N can be obtained, and this improvement in S/N increases the jitter correction effect.

In the embodiments described above, a reproduced horizontal burst signal corresponding to a positive slope positive synchronization signal is detected, or a reproduced horizontal burst signal corresponding to a negative slope positive synchronization signal may be detected. Moreover, although the case has been described in which the timing of the zero crossing of the horizontal burst signal and the timing of the positive synchronization signal are made to match, there is no problem in selecting the timing of both arbitrarily.

Furthermore, in the above embodiment, the frequency of the pilot signal (fP
) is selected higher than the frequency of the horizontal burst signal (fHB), or fP < f! (A similar effect can be obtained with B.

In the above embodiments, the case where recording is performed by magnetically recording on a tape has been explained; however, a magnetic disk device, a recording/playback device using magneto-optical recording, an optical type and a capacitance type video disk device may be used; The same effects as in the embodiment described above are also achieved.

[Effects of the Invention] As described above, according to the present invention, a video signal having a positive synchronization signal is FM-modulated, frequency-multiplexed with a horizontal burst signal and a pilot signal, and recorded. There is no need to time-base compress the video signal and insert the negative synchronization signal and the burst signal.

Therefore, during FM modulation, the frequency deviation assigned to the negative synchronization signal level is no longer necessary, and the frequency deviation of the video signal level is correspondingly increased to facilitate recording of C, S, and /N. can.

In addition, since the time axis compression of the video signal during recording is not necessary, the frequency bandwidth of the video signal to be recorded does not change, and the recording bandwidth becomes smaller than that of the conventional method.

In addition, there is no need for a video signal time axis compression processing circuit for recording, which consists of an A/D, D/A converter, memory, etc., and there is no need for time axis expansion processing during playback. The circuit configuration is very simple and the entire device can be constructed at low cost.

In addition, by recording the slope of the positive synchronization signal and the level change of the horizontal burst signal in correspondence, even if a dropout occurs, a crank pulse is immediately generated as soon as the dropout disappears, allowing reliable ramp operation. It is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a recording/playback device according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining the operation, and FIG. 3 shows the slope of the positive synchronization signal of the MUSE signal. Figure 4 shows the frequency spectrum of the FM-modulated MUSE signal, horizontal burst signal, and pilot signal. Figure 5 shows frequency-multiplexed recording and reproduction of sine waves of frequencies (fl) and (f2). FIG. 6 is a frequency spectrum diagram for explaining the generation of unnecessary components in the case of the conventional device, and FIG. 6 is a signal waveform diagram for explaining the operation of the conventional device. (2)...FM modulator, (3)...synchronous separation circuit,
(4)...Horizontal burst signal generator, (6)...Pilot signal generator, (7)...Adder, (8)...
・Recording amplifier, (11)...Playback amplifier, (13)・
...FM demodulator, (16) ...zero cross detector, (
17)...Differential circuit, (18)...Comparator,
(19)...Clamp pulse generation circuit, (20)...
- Clamp circuit, (21)...Time base collector, (22)...A/D converter, (23)...Write clock circuit, (24)...Memory, (26)...
D/A converter, (27)...read clock circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A recording and reproducing apparatus for recording a video signal having a positive synchronization signal, including means for FM modulating the video signal, and a horizontal burst signal in which a level change of the horizontal burst signal and a slope of the positive synchronization signal have a constant relationship. , a means for generating a pilot signal for jitter detection, and a means for recording and reproducing these signals by frequency multiplexing, and generating a crank pulse for clamping the video signal from the horizontal burst signal during reproduction. 1. A recording and reproducing apparatus comprising: means and a write clock circuit that generates a write clock for A/D converting the reproduced video signal from the pilot signal. (2) The recording and reproducing apparatus according to claim 1, further comprising means for detecting positive synchronization signal position information from the horizontal burst signal during reproduction.