JPS61181286A - Digital recorder of picture signal - Google Patents

Abstract

PURPOSE:To record a picture signal having a signal band being several times that of an existing television set in less bit number by using band compression utilizing exquisitely the advantage of the digital recording system. CONSTITUTION:A low frequency component YL is extracted from a luminance signal Y by an LPF1 and the YL is subtracted from the Y at a subtraction circuit 2 to extract a high frequency component YH. The YH component is subjected to amplitude modulation by using a carrier in frequency fv/2 by an amplitude modulation signal device 3, the lower side band component is extracted by an LPF4 to obtain a high frequency component subjected to low frequency conversion. Then the result is multiplexed with the YL component by an adder circuit 5. The band of the luminance signal is subjected to band compression into a half as 0-fv/2H2 in this stage. The video image is shared by a data sharing circuit 7 is response to the recorded channel number, and a signal is subjected to processing such as shaffling and addition of error correction code by a coding circuit 8 and the result is converted into a code switable for the digital recording by a modulator 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an image recording device, and particularly to a magnetic recording device suitable for digital recording of a broadband image signal of a high-definition, high-quality image.

[Background of the invention]

In general, for recording images, especially television signals, a well-known method is to record an analog signal by FM modulating it. However, with this method, S/
The problem was deterioration of H. As a solution to this problem, a method has been considered in which the television signal is converted into a digital signal by sampling and quantization, and the digital signal is recorded. With this digital method, it is possible to achieve a S/N that is approximately 10 dB higher than that of the analog method, and there is no deterioration in S/N due to dubbing, no jitter, etc.
It has excellent features. On the other hand, there is a problem that the number of recording bits increases by one order of magnitude or more due to the analog method.

In particular, high-definition TVs and high-definition TVs that provide images with higher resolution and higher quality than current TVs require a signal bandwidth several times more than current TVs, and the number of recording bits also increases. The number will increase dramatically. Therefore, in order to realize such an image signal using a digital recording method, it is important to reduce the number of recording bits.

In digital processing of image signals, methods for reducing the number of required bits include orthogonal transformation and differential PCM (DP side).
However, these methods have the problem that if a code error occurs during the recording/reproducing stage, this code error will be propagated across multiple pixels during decoding. . These methods are not necessarily suitable for digital recording because the bit error rate is as low as about 10-G.

[Purpose of the invention]

An object of the present invention is to provide an apparatus that records an image signal having a signal band several times larger than that of a current television with a small number of recording bits by band compression that makes good use of the features of the digital recording system.

[Summary of the invention]

In order to achieve the above object, the present invention utilizes the characteristics of digital recording, converts the high frequency component of an image signal into a low frequency signal by frequency shifting, and converts the high frequency component of the image signal into a low frequency signal by frequency interleaving. The shifted high-frequency components are multiplexed and recorded as a digital signal.

To explain in more detail, one of the features of digital recording is that
There may be no jitter during playback. That is, the digital signal during recording can be reproduced with the correct phase during reproduction.

FIG. 1 shows a diagram of the principle of the present invention. For example, in images from high-definition television, the band of the luminance signal is also increasing, as shown in (,). Here, the low-frequency signal YL acid component is the same as that of current televisions, but a high-definition signal Y□ exists as a high-frequency component. In the present invention, as shown in (b), this high-frequency component YY is frequency-converted to a low-frequency component (shaded area) by frequency shifting, and multiplexed with the low-frequency component YL using a frequency interleaving technique, thereby converting the signal band. Compress the bandwidth to less than 1/2. Here, since the signal spectrum is frequency interleaved, the Y component and the low frequency converted YH acid component do not overlap with each other. In this way, digital recording is performed after band compression. Here, compared to digitally recording the signal in state (a), it is possible to reduce the required number of recording bits to 1/2 or less by band compression.

On the other hand, the reproduced signal is extracted by a low frequency converted YM acid component comb filter, and demodulated into the original high frequency component by frequency shift inverse conversion. If the signal component contains jitter during demodulation, it cannot be accurately converted to the original signal.
Since no jitter occurs due to digital recording, correct demodulation can be performed.

As described above, one aspect of the present invention is to digitally record an image signal in which a high-frequency component signal is multiplexed with a low-frequency component signal using a frequency interleaving method, thereby significantly reducing the number of recording bits required.

Furthermore, even if a code error occurs during digital recording or playback, according to the band compression of the present invention, this effect will be limited to the corresponding pixel, and error propagation as seen in band compression such as DPCM will not occur. do not.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG.

FIG. 2(a) shows a recording section, and FIG. 2(b) shows a reproducing section.

This embodiment shows the case of a component-type image signal in which a luminance signal and a color signal are each separated.

First, the operation of the recording section will be explained. Luminance signal (
The signal band 0 to JvH2) is the cutoff frequency f, /2
A low-pass filter 1 extracts low frequency components Y, . A subtraction circuit 2 subtracts Y or Yo to extract the high frequency component YR. The Y and I components are generated by the amplitude modulation signal generator 3, and the fv/2
Amplitude modulation is performed using a carrier wave having a frequency of , and a low-pass filter 4 extracts this lower band component to obtain a high frequency component that is low-band converted to 0 to fv/2 Hz. Note that frequency interleaving is realized by inverting the phase of the carrier wave of the amplitude modulator for each line. Then, an adder circuit 5 multiplexes the YL acid components. At this stage, the luminance signal band is 0-fv/2H
The band is compressed to half that of z. Next, the A/D converter 6
Convert to a digital signal at a sampling frequency of vH2 or higher.

The color signals C□ and C2 are also subjected to band compression using the same method as the luminance signal. The configuration is the same as that of the luminance signal, so the illustration is omitted. The data distribution circuit 7 distributes data according to the number of recording channels. In each channel, an encoding circuit 8 performs processing such as shuffling and addition of an error correction code. Then, the code is converted by a modulator 9 into a DC-balanced code suitable for digital recording and recorded on a medium such as a tape.

Next, the configuration on the playback side will be explained. The reproduced signal of each channel undergoes signal processing such as waveform equalization in a demodulator 10 to reproduce a digital signal. This signal is subjected to signal processing such as code error correction and deshuffling by a decoding circuit 1-1, and a luminance signal and a color signal are reproduced by a data separation circuit 12. Next, D/A converter 1
The luminance signal converted into an analog signal by 3 is processed by a comb filter] 4 to extract a low-frequency converted signal component, and a subtraction circuit 15 removes this component.

Regenerate ingredients. On the other hand, the detection circuit [6] performs synchronous detection using a carrier wave whose frequency is fv/2 and has the same phase as that during recording, and the bypass filter [7] extracts this upper sideband component and demodulates it to the original Y and I components. do. Then, by adding the YL acid components in the adding circuit 18, the original luminance signal (0-fvHz) is reproduced. Since the chrominance signal is similar to the luminance signal, a description thereof will be omitted.

Second, although this embodiment shows a case where processes such as frequency shifting are performed in analog form, these processes can also be implemented using digital signals as they are.

An example in this case is shown in FIG. It should be noted that the steps from the data distribution circuit in the recording section to the data separation circuit in the reproducing section are the same as those in the embodiment shown in FIG. 2, and are therefore omitted in the embodiment shown in FIG.

First, the recording section will be explained. Luminance signal Y (0~f
v Hz) at sampling frequency f.

(f, > 2 fv) and is converted into a digital signal by an A/D converter] 9. YL by low pass filter 20
The acid component 0 to fv/2) is separated, and the YL acid component is subtracted from Y in the subtraction circuit 2 to extract the Y□ acid component. Amplitude modulator 2
2, amplitude modulation is performed using a carrier wave with one frequency of fv/2 Hz, and a low-pass filter 23 extracts a lower sideband component. Note that the phase of the carrier wave during amplitude modulation is inverted for each line to realize frequency interleaving. The addition circuit 24 multiplexes the YL acid components, and the sampling frequency conversion circuit 25 converts them into a signal sequence with a sampling frequency of fa/2 Hz. As a result, the required number of recording bits of the luminance signal is reduced to 1/2.

Since the color signals C, , C operate in the same manner as the luminance signal, their explanation will be omitted here.

Next, the operation of the reproduction section will be explained. From the data separation circuit, the luminance signal has a sampling frequency of f.

A 72 Hz digital signal is obtained. The sampling frequency conversion circuit 26 converts the signal into a signal sequence with a sampling frequency of f, and the comb filter 27 extracts the YII component that has been low-pass converted. The subtraction circuit 28 takes the difference from this signal and extracts the YL acid component. On the other hand, in the detection circuit 29, f
Synchronous detection is performed with a carrier wave of v/2 Hz, and this upper sideband component is extracted by the bypass filter 30, and Y,
Demodulate the I component. Then, the addition circuit 3 adds the YL acid components, and the D/A converter 32 reproduces the signal as the original luminance signal Y. The same applies to the color signals C□ and C2, so a description thereof will be omitted.

Note that in this embodiment, the filters can be realized by so-called digital filters.

FIG. 4 shows a case where the present invention is applied to a so-called composite image signal in which a color signal is multiplexed with a luminance signal.

In the composite form, the luminance signal YL and color signal C are already multiplexed by frequency interleaving,
As shown in the figure, there are still gaps in the signal spectrum.

In this gap, the high frequency components Y and I are further converted to a low frequency and multiplexed with one frequency interleave.

FIG. 5 shows an embodiment for realizing this. First, the operation of the recording section will be explained. Luminance signal (0~f v Hz
), the low-pass filter 33 extracts the YL acid component, and the subtraction circuit 34 extracts the Y and I components.

A Y□ acid component amplitude modulator 35 performs amplitude modulation with a carrier wave of fv/2H7, a low-pass filter 36 extracts a lower sideband component, and performs low frequency conversion. On the other hand, the color signals C1, C, are sent to the amplitude modulator 37 at f. Orthogonal modulation is performed using the carrier wave (fo<fv/2). In this case, the phase of f is inverted for each line, for example. Further, the phase of the f7/2 carrier wave is inverted for each line and each field. In this way, Y5, the reduced-converted Y□, and the color signal can have a frequency interleaved relationship with each other. Then, an adder circuit 38 multiplexes these signals, and an A/D converter 39 converts them into digital signals. Then, the data distribution circuit 40 distributes the data for the recording channels. In each channel, an encoding circuit 41 performs processing such as shuffling and addition of an error correction code, and a modulator 42 converts the signal into a code suitable for digital recording and records the signal in one step.

On the other hand, in the reproducing section, the reproduced signal of each channel is sent to a demodulator 43.
It performs waveform equalization etc. and converts it to the original digital signal. Then, a decoding circuit 44 performs processing such as error correction and deshuffling, and this signal is converted into an analog signal by a D/A converter 46, and a comb filter 47 converts the signal to YL? Separate into C1 and reduced-converted YII components. The detection circuit 48 performs synchronous detection using the fv/2 carrier wave, and the bypass filter 49 detects the upper sideband component and demodulates the YII component. Then, the addition circuit 50 adds the Y component and reproduces the luminance signal Y.

On the other hand, the color signal C is synchronously detected by the carrier wave of fo in the detection circuit 51, and is detected as Low Pa5s Fj,]ter52.53.
by 01. Regenerate C2 component.

In this embodiment, the frequency shift is shown in analog form, but it is clear that these processes can also be performed digitally.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the number of recording bits required and record and reproduce high-quality, high-definition images, resulting in extremely large effects.

[Brief explanation of the drawing]

Figure 1 is a frequency distribution diagram for explaining the principle of the present invention, Figure 2 is a frequency distribution diagram for explaining the principle of the present invention.
3 and 5 are configuration diagrams of an embodiment of the digital recording apparatus according to the present invention, and FIG. 4 is a frequency distribution diagram for explaining the operating principle of the embodiment shown in FIG. 1.4. ．． 20, 23, 33, 36, 52.53...
Low pass filter, 17, 30. 49... High pass filter, 14, 27, 47... Comb filter, 3.2
2, 35.37... Amplitude modulation circuit, 16°29.48
,51...detection circuit, 2,15,21゜28.34・
... Bento calculator, 5.18, 24.3:L. 38.50...addition circuit, 6,19.39...A/
D converter, 13, 32, 46... D/A converter, 7° 40... Data distribution circuit, 12.45... Data separation circuit, 8, 41... Encoding circuit, 9, 42...Modulator, 10.43...Demodulator, 11,44...Decoding circuit, %r mouth

Claims (1)

[Claims] An image characterized by converting a high frequency component of an image signal into a low frequency signal by frequency shifting, and recording a signal obtained by multiplexing a high frequency component frequency shifted by frequency interleaving onto the low frequency component of the image signal as a digital value. Digital recording device for signals.