JPH03178282A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a video signal with high picture quality based on a reference signal with excellent S/N by recording and reproducing an analog sample signal with a reference signal inserted therein to compensate its transmission characteristic and transmitted. CONSTITUTION:The device is provided with a VITS(Vertical Interval Test Signal) signal extraction circuit 18, a recording characteristic memory 19, a transmission recording calculation circuit 20, a transmission recording characteristic insertion circuit 21, a reproduction characteristic memory 22, a transmission recording characteristic decoding circuit 23, a VITS signal calculation circuit 24 and an overall VITS signal insertion circuit 25. In this case, the overall information representing the recording characteristic of the transmission line and the recording VTR is stored as a digital signal together with the video signal, and a reference signal with excellent S/N including the information of all processes of transmission, recording and reproduction obtained from the characteristic is inserted to a prescribed portion of the reproduction video signal generated separately from the reproduction signal and the result is outputted. Thus, the reference signal with excellent S/N is obtained and the video signal with high picture quality is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a video signal recording and reproducing device. In particular, MUSE, which is known as a transmission method for high-definition signals,
(Multiple 5ub-Nyquist Sam
The present invention relates to a device for recording and reproducing signals compatible with an analog sample value transmission method such as a plingencoding method.

(Prior technology) MUS is known as a band compression method for high-definition signals.
The E method uses P obtained by sampling an analog signal.
AM (Pulse Amplitude Modula)
This is one of the analog sample value transmission methods that transmits the signal as is.

This technology is called PCM (Pulse Code Mod).
The transmission band required is smaller than that of digital transmission methods such as ULATION). However, the quality of the transmission system is required to be much higher in terms of S/N, amplitude characteristics, five-phase characteristics, time axis fluctuations, etc.

Since the signal transmitted by the MUSE method is an analog sample value, the receiver must resample it at exactly the same timing as the transmitter and reproduce the same amplitude. However, the transmission path until the baseband MUSE signal is demodulated is generally not ideal. Therefore, measures have been taken to compensate for the characteristic deterioration that occurs in actual transmission lines.

This is V I T S (Vertical Inte
A single pulse signal called the Rval Te5t Signal) is inserted into the blanking period of the video signal for transmission, and the receiving side calculates the transmission characteristics from the received waveform and implements a filter with characteristics that compensates for the transmission. The objective is to obtain a high quality MUSE signal by compensating for the path characteristics. FIG. 2 shows the waveform of the VITS signal, which is a reference signal included in the MUSE signal.

If no transmission distortion is applied, an accurately resampled VITS signal will be as shown in FIG. 2(a). Here O is the value resampled at the Nth frame, × is the (Nth
-1) is the value to be resampled in the frame. but,
Actually, it is subjected to some kind of distortion as shown in FIG. 2(b). This shows the impulse response of the transmission system. Ideally, the sample point that should be the zero crossing point is not zero, so the resampled signal is passed through a transversal filter with variable coefficients so that it becomes zero, and by appropriately selecting the coefficients, the transmission system can be improved. The overall characteristics of the impulse response and this filter can be brought close to ideal. The above is the function of the VITS signal employed in the MUSE system.

FIG. 5 shows the configuration of a conventional MUSE-VTR (video tape recorder) that records analog signals including MUSE signals and VITS signals. In Figure 5, 1 is MU
SE video signal input terminal, 2 is MUSE synchronization separation circuit,
3 is a clock generation circuit, 4 is an A/D converter on the recording side, 5
is a recording side video signal processing circuit, 6 is a recording side D/A converter, 7 is an FM converter, 8 is a recording amplifier, 9 is a recording head,
■0 is the tape, 11 is the playback head, 12 is the playback amplifier,
13 is an FM demodulator, 14 is an A/D converter on the playback side, 15
16 is a reproduction side video signal processing circuit, 16 is a reproduction side D/A converter, and 17 is an output terminal for the MUSE video signal.

Next, the operation of this conventional example will be explained. A MUSE signal is input to input terminal 1 of the MUSE video signal. M'US
The E-synchronization separation circuit 2 separates the MUSE synchronization signal, and a clock generation circuit 3 generates a synchronization signal and a clock that are phase-synchronized with the MUSE synchronization signal. Using this clock, the input MUSE signal is resampled by the A/D converter 4 and becomes a digital video signal. At this time, the clock generation circuit 3 also controls the resampling phase based on the frame synchronization and horizontal synchronization signals, and resampling is performed at the optimum resampling phase. At this time, the VITS signal, which is a reference signal included in the MUSE signal, is also resampled and becomes a digital signal. These digital signals are subjected to processing such as time axis conversion channel division and recording synchronization signal insertion, and are converted into a format suitable for recording. Various methods can be considered for this, but the details are omitted because they are not directly related to the gist of the present invention. The above processing is performed by the recording side video signal processing circuit 5. This signal is converted back into an analog signal by a D/A converter 6, FM modulated by an FM converter 7, and recorded on a tape 10 by a recording amplifier 8 and a recording head 9. Needless to say, when channel division is performed here, recording heads corresponding to the number of channels are required.

During reproduction, the signal reproduced by the reproduction head 11 is amplified by the reproduction amplifier 12, FM demodulated by the FM demodulator I3, and then digitized by the reproduction side A/D converter 14. This signal is subjected to processing by the reproduction side video signal processing circuit 15 that is the reverse of the processing performed by the recording side video signal processing circuit.

The original MUSE signal is obtained at the output terminal 17 by the reproduction side D/A converter 16. At this time, the recorded VITS signal is also output in the same way as the video signal. These signals are MU
It is decoded by the SE decoder to obtain the original video.

(Problem to be Solved by the Invention) However, in the conventional analog recording VTR described above, the MUSE signal including the VITS signal is recorded as is, but in this case, the video signal and the VITS signal are It is affected by both recording and playback characteristics. The decoder corrects the video signal using the overall characteristics of the transmission path and recording/reproduction obtained from the reproduced VITS signal. However, in general, the S/N of the playback signal of an analog recording VTR is not good, so the resulting VITS
The signal-to-noise ratio of the signal is also poor.Generally, if the characteristics are compensated based on a reference signal with a degraded S/N, the information obtained therefrom will be incorrect and the original signal will be further degraded.

In the case of the above-mentioned VTR, the attempt is made to obtain information on the transmission characteristics including the recording/reproducing system from the reproduced reference signal with a poor S/N ratio, and there is a sufficient risk of this.

The present invention solves the above-mentioned conventional problems, and
The purpose is to obtain a high-quality video signal based on a reference signal with good H.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides means for obtaining characteristics of a transmission system from a reference signal included in an input video signal when recording on a VTR, and means for storing unique recording characteristics; means for obtaining comprehensive characteristics of the transmission system and recording system from this information; means for digitally recording and reproducing this information together with analog video signals; A means for decoding information, a means for storing information on reproduction characteristics specific to the VTR in the VTR used for reproduction, and comprehensive characteristics of transmission, recording and reproduction from the decoded information and the stored reproduction characteristic information. means for obtaining a reference signal through this characteristic;
The apparatus includes means for adding and outputting the reference signal to a predetermined portion of the reproduced video signal during R reproduction.

(Function) Therefore, with the above-described configuration, the video signal recording and reproducing apparatus according to the present invention records comprehensive information on the recording characteristics of the transmission path and the recording VTR together with the video signal as a digital signal, and at the time of reproduction, the reproduction VTR has A reference signal with a good S/N ratio, whose characteristics are memorized and which includes information on all processes of transmission, recording, and playback obtained from these, is generated separately from the playback signal and inserted into a predetermined part of the playback video signal. This is how it comes out.

(Embodiment) FIG. 1 shows a block configuration of a video signal recording and reproducing apparatus in a first embodiment of the present invention. In FIG. 1, the same parts as in FIG. 5 are indicated by the same numbers.

18 is a VITS signal extraction circuit, 19 is a recording characteristic memory,
20 is a transmission/recording characteristic calculation circuit, 21 is a transmission/recording characteristic insertion circuit, 22 is a reproduction characteristic memory, 23 is a transmission/recording characteristic decoding circuit, 24 is a VITS signal calculation circuit, and 25 is a general VITS signal input circuit. .

Next, the operation of the first embodiment will be explained. A MUSE signal is input to the MUSE video signal input terminal l. MUS
The E-synchronization separation circuit 2 separates the MUSE synchronization signal, and a clock generation circuit 3 generates a synchronization signal and a clock that are phase-synchronized with the MUSE synchronization signal. Using this clock, the input MUSE signal is digitized or resampled by the A/D converter 4. At this time, the clock generation circuit 3 also controls the resampling phase based on the frame synchronization and horizontal synchronization signals, and resamples at the optimal resampling phase. At this time, the VITS signal, which is a reference signal included in the MUSE signal, is also resampled and becomes a digital signal. If no transmission distortion is applied, an accurately resampled VITS signal will be as shown in FIG. 2(a). However, in reality, some kind of distortion occurs as shown in FIG. 2(b).

As explained in the conventional example section, this shows the impulse response of the transmission system, and the VITS signal extraction circuit 18 extracts these sample values.

The transmission characteristics of the recording system of this VTR are stored in a recording characteristics memory 19. This content is, for example, an impulse response of recording characteristics. The transmission/recording characteristic calculation circuit 20 obtains the total impulse response of the transmission system and recording system from these. On the other hand, the A/D converted video signal is converted into a format suitable for recording by the recording side video signal processing circuit 5, and then
The D/A converter 6 converts the signal back into an analog signal. Next, the transmission/recording characteristic insertion circuit 21 inserts into this analog recording video signal a digital signal of a sample value of the overall impulse response of the transmission system and recording system. The insertion position may be anywhere as long as it does not affect the MUSE video signal, audio signal, or control signal. Originally V
It may be inserted at the desired position of the IST signal. This signal is FM modulated by an FM modulator 7 and recorded on a tape 10 by a recording amplifier 8 and a recording head 9.6 During reproduction, the signal reproduced by the reproduction head 11 is amplified by a reproduction amplifier 12, and then is transmitted to an FM demodulator 13. , FM demodulation is performed, and then digitized by the reproduction side A/D converter 14. After this signal is processed by the playback side video signal processing circuit 15 in the opposite manner to the processing performed by the recording side video signal processing circuit, it passes through the VITS signal insertion circuit 25 and is also processed by the playback side D/A converter 16. A MUSE signal is obtained.

The digital signal of the sample value of the overall impulse response of the transmission system and recording system inserted and recorded during recording is transmitted and recorded.
It is read out by the recording characteristic decoding circuit 23. On the other hand, V
The impulse response of the reproduction characteristic of the TR is stored in the reproduction characteristic memory 22.

The overall characteristic calculation circuit 24 calculates the overall impulse response of transmission, recording, and reproduction, and the VIST signal calculation circuit 24 calculates the overall VITS signal.
The VITS signal is inserted into the normal position of the MUSE signal to be outputted by the ITS signal insertion circuit 25 and outputted. According to this embodiment, since the total VITS signal can be obtained without passing through the analog recording/reproducing system, the decoder can compensate for the transmission recording/reproducing system with high accuracy.

Third. The figure shows a second embodiment of the invention. Components common to FIGS. 1 and 5 are designated by the same numbers. 26 is a transmission equalization coefficient calculation circuit, 27 is a transversal filter with variable coefficients, 28 is a recording characteristic insertion circuit, and 29 is a recording characteristic decoding circuit. .

Since the operation of the second embodiment is similar to that of the first embodiment, only the different parts will be explained. The VITS signal extraction circuit 18 extracts a predetermined sample value of the VITS signal. Similar to the process explained in the conventional example section, the transmission equalization coefficient calculation circuit 26 selects the optimum coefficients of the transversal filter 27 with variable coefficients and passes the coefficients to the VT.
Distortion in the transmission system up to input to R is removed. After the video signal processed as described above is converted into a form suitable for recording by the recording side video signal processing circuit 5, it is converted back to an analog signal by the D/A converter 6, and the recording characteristic insertion circuit 28 converts the video signal into a format suitable for recording. After inserting the information, it is FM modulated by the FM modulator 7 and sent to the recording amplifier 8 and the recording head 9.
The data is recorded on the tape 10 by the following. Through the above recording process, the characteristics of the transmission path immediately before being input to the VTR are corrected, and only the recording characteristic information is recorded together with the video signal. The operation on the playback side is also very similar to the first embodiment.

The difference is that in the first embodiment, the information read from the tape was the transmission/recording characteristics, whereas in the second embodiment, the information was the recording characteristics.

In the first embodiment, the transmission system has a small time axis error and good S/N, and the time axis error is relatively large and the S/N is poor.In comparison, the VTR left equalization is performed all at once at the end. In this example, since only the transmission system is equalized before recording, errors are not accumulated and better image quality can be obtained.

FIG. 4 shows a third embodiment of the invention. Fourth
In the figure, the same parts as in FIGS. 1, 3, and 5 are designated by the same numbers, and 30 is a VITS signal memory.

Next, the operation of the third embodiment will be explained.

From the impulse response of the transmission system obtained by the VITS signal sampling circuit 18 and the recording characteristics of the VTR stored in the recording characteristic memory 19, the transmission/recording characteristics calculation circuit 20 calculates the overall transmission/recording characteristics, and calculates the variable coefficients. By changing the coefficients of the transversal filter 27, the transmission/recording characteristics are equalized and recorded.

During playback, the VITS signal that is obtained from the impulse response of the playback characteristics unique to this VTR is recorded.
The VITS signal is read from the signal memory, added to a predetermined position of the reproduced video signal, and output.

In this embodiment, the transmission system and the recording system are corrected during recording. Transmission characteristics when recording.

There is no need to record information on recording characteristics. Therefore, no errors occur because digital information is not recorded or reproduced. Furthermore, there is no need to calculate the VITS signal during playback, and it is only necessary to output the stored VITS signal, which simplifies the circuit on the playback side.

(Effects of the Invention) As is clear from the above embodiments, the present invention provides a reference signal with a good S/N ratio that does not pass through an analog recording/reproducing system in a VTR that records an analog sample value signal. Transmission characteristics can be corrected, and as a result, high-quality video signals can be reproduced on a display.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a video signal recording device according to a first embodiment of the present invention, FIG. 2 is a diagram showing an example of a VITS signal, and FIG. 3 is a diagram showing a video signal according to a second embodiment of the present invention. FIG. 4 is a block diagram of a video signal recording and reproducing apparatus according to a third embodiment of the present invention, and FIG. 5 is a block diagram of a conventional MUSE signal analog recording VTR. 1...Video signal input terminal, 2...Synchronization separation circuit, 3...Clock generation circuit, 4.14...A
/D converter, 5... Recording side video signal processing device, 6
, 16... D/A converter, 7... FM modulator,
8...recording amplifier, 9...recording head, 1
0...Tape, 11...Playback head, 12...
- Reproduction amplifier, 13... FM demodulator, 15... Playback side video signal processing circuit, 17... Video signal output terminal, 18... VITS signal extraction circuit, 19... Recording characteristic memory, 20...Transmission/recording characteristic calculation circuit, 2
DESCRIPTION OF SYMBOLS 1... Transmission/recording characteristic insertion circuit, 22... Reproduction characteristic memory, 23... Transmission/recording characteristic decoding circuit, 24...
- VITS signal calculation circuit, 25 - VITS signal insertion circuit, 26... Transmission equalization coefficient calculation circuit, 27... Transversal filter, 28... Recording characteristic insertion circuit, 29... Recording characteristic decoding circuit, 30...VITS signal memory.

Claims (3)

[Claims] (1) A device that records and plays a transmitted analog sample value signal by inserting a reference signal for compensating the transmission characteristics, and the device records and reproduces the transmitted analog sample value signal by inserting a reference signal to compensate for the transmission characteristics, and the device records and reproduces the transmitted analog sample value signal by inserting a reference signal to compensate for the transmission characteristics, and the device records and reproduces the transmitted analog sample value signal by inserting a reference signal to compensate for the transmission characteristics. means for obtaining characteristics of a transmission system; storage means for storing recording characteristics specific to the recording and reproducing apparatus; means for obtaining characteristics of the transmission system; and a synthesis of the transmission system and the recording system from information read from the storage means means for obtaining the characteristics, means for digitally recording and reproducing information on the obtained comprehensive characteristics together with an analog video signal, means for decoding the information reproduced together with the video, and information on the reproduction characteristics specific to the recording and reproducing device. a storage means for storing the information, a means for creating a signal equivalent to the signal obtained when the reference signal passes through the comprehensive characteristics of transmission, recording and reproduction from the decoded information and the stored reproduction characteristic information; A video signal recording and reproducing apparatus characterized by comprising: means for adding the created equivalent signal to a predetermined portion of a reproduced video signal and outputting the same. (2) A device that records and plays a transmitted analog sample value signal by inserting a reference signal for compensating the transmission characteristics, and the device records and reproduces the transmitted analog sample value signal by inserting a reference signal to compensate for the transmission characteristics, and the device records and reproduces the transmitted analog sample value signal from the reference signal containing distortion of the transmission system included in the input video signal. means for obtaining characteristics of a transmission system; means for equalizing a video signal from the obtained transmission characteristics; storage means for storing recording characteristics specific to the recording/reproducing apparatus; means for digitally recording and reproducing together with an analog video signal equalized by means for equalizing the video signal; means for decoding information reproduced together with the video; and storing information on reproduction characteristics specific to the recording and reproducing device. means for creating a signal equivalent to the signal obtained when the reference signal passes through the comprehensive recording and reproducing characteristics from the decoded information and the stored reproduction characteristic information; and a signal equivalent to the generated signal at the time of reproduction. 1. A video signal recording and reproducing apparatus, comprising means for adding and outputting a predetermined portion of a reproduced video signal. (3) A device that records and plays back the transmitted analog sample value signal by inserting a reference signal for compensating the transmission characteristics, and the device records and reproduces the transmitted analog sample value signal by inserting a reference signal to compensate for the transmission characteristics, and the device records and reproduces the transmitted analog sample value signal from the reference signal containing the distortion of the transmission system included in the input video signal. means for obtaining characteristics of a transmission system; storage means for storing recording characteristics unique to the recording/reproducing apparatus; means for equalizing a video signal from the obtained transmission characteristics and the stored recording characteristics; storage means for storing a signal obtained when a reference signal is passed through a reproduction characteristic unique to a reproduction device; and means for adding the signal read from the storage means during reproduction to a predetermined portion of a reproduced video signal and outputting the signal. A video signal recording and reproducing device comprising: