JPH0554758B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to a component video signal (a signal consisting of a luminance signal of a color television video signal and two types of color signals or three primary color signals (R, G, B)). A signal band that can be recorded or transmitted using a recording device or narrowband transmission line that has only half the bandwidth of the highest frequency of the original component video signal. This relates to compression methods.

[Summary of the Disclosure] The present invention is a method for recording or transmitting a component video signal on a video tape recorder (VTR) by reducing the signal bandwidth to about half. The signal bandwidth is compressed to 1/2 of the input component video signal (original component video signal) by creating a mutual frequency interleave relationship, multiplexing, and expanding the time axis by twice.

[Prior Art] Examples of frequency interleaving multiplexing in television video signals include the NTSC system and RAL system for color television signals (for example, the ``Digital signal processing of images''
(Published by Nikkan Kogyo Shimbun on May 25, 1982) Chapter 2 p.18-20
reference).

The case of the NTSC system will be briefly explained. In the NTSC system, color subcarriers are quadrature-two-phase modulated using color signals (I, Q signals) and multiplexed onto a luminance signal.
At this time, the frequency fsc of the color subcarrier is fsc=455×f _H /2. Here, f _H : horizontal scanning frequency (15.75k
Hz), the carrier color signal is in a frequency interleaved relationship with the luminance signal. For this reason,
Even if the chrominance signal (I signal 1.5MHz, Q signal 0.5MHz) is added to the luminance signal 4.5MHz, the overall transmission bandwidth is reduced to 4.5MHz.

In the NTSC system, the bandwidth of the chrominance signal is less than half that of the luminance signal, so the above method can reduce the transmission bandwidth. On the other hand,
For signals having the same signal bandwidth, such as luminance signals, the transmission bandwidth cannot be reduced by the above method.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a band compression method for component video signals that can eliminate the above-mentioned drawbacks and reduce the recording or transmission bandwidth of color television video signals. It lies in resisting.

[Means for solving the problems] In order to achieve such an object, the present invention has the following features:
After sequentially cutting out signals of a predetermined period of time from the original component video signal as units, and changing two adjacent signals among the sequentially cut out signals into two-channel signals that occur simultaneously, The signals of these two channels are multiplexed to maintain a frequency interleaving relationship with each other to make one channel signal, and then the time axis is expanded to a signal with a 2τ period, or the changed two channel signals are converted into a signal with a period of 2τ, respectively. After axial expansion, multiplexing is performed while maintaining a mutual frequency interleaving relationship to create a single channel signal, and the video signal bandwidth is approximately 1/2 of the original component video signal1.
It is characterized by performing band compression on channel signals.

[Operation] According to the method of the present invention, focusing on the spectral structure peculiar to the component video signal of a color television signal, the component video signal is divided into two parts, a mutual frequency interleaving relationship is created, multiplexing is performed, and the time axis is divided into two parts. By stretching it twice,
It is possible to compress the video signal bandwidth to 1/2.

[Example] The present invention will be described in detail below with reference to the drawings.

First, FIG. 2 shows the spectral structure of the luminance signal among the component video signals. The component video signal consists of discrete frequency components for each frame frequency _fF , and in particular, there is a large component for each horizontal operation frequency _fH . Focusing on this spectrum, it can be seen that another signal having a frequency interleaving relationship can be inserted into the valley where there is no signal component.

Therefore, by dividing the input luminance signal into two, creating a frequency interleave relationship, multiplexing, and then expanding the time axis by twice, the signal band of the luminance signal can be halved.

The same applies to two types of color signals that are other component video signals, but in the embodiment described below, the two types of color signals are handled as one signal and the present invention is applied.

An embodiment of the signal processing circuit on the recording side or the transmitting side according to the present invention is shown in FIG. 1, and the signals of each component of the circuit will be explained in detail while looking at the transition on the time axis and the transition on the spectrum.

First, the flow of signals will be explained with reference to FIG. Input component video signals such as luminance signals to 2
One of the signals is delayed by the time τ in the delay device 1, and then is delayed by the frequency _τ in the frequency shift circuit 2.
The frequency is shifted by 2 to form a delayed signal in a frequency interleaved relationship with the input signal. This delayed signal and the unprocessed input component video signal are added by an adder 3 in a frequency interleaved manner to create a multiplexed signal. Here, since the input signal and the signal with the delay time τ are multiplexed, the time axis is doubled by the timing signal t which is generated every 2τ in the time axis expansion circuit 4, so that the input signal is approximately The signal has half the frequency bandwidth.

Next, the operation of the above circuit will be explained using FIG. 3, which shows the spectrum of a signal corresponding to the transition on the time axis. Here, the highest frequency of the input component video signal is assumed to be fm. The input component video signals are divided by time τ as shown in FIG. 3 and are named A, B, . . . , E. The spectrum exists up to fm for each frame frequency _fF .
Since is the signal after passing through the delay device 1 and the frequency shift circuit 2, the time axis is delayed by the time τ with respect to the signal, and A becomes a signal corresponding to the time of B of the input signal. The spectrum is frequency shift circuit 2
This results in an upward shift of f _H /2 from the input signal, so the highest frequency is fm+f _H /2. In the adder output, for example, A and B are multiplexed within the period of time τ (indicated by A+B), but they are added in a frequency interleaved relationship as shown in the spectrum, so crosstalk between the signals is Does not occur. Here, among the B+C signals, B is included in A+B before τ, and C is included in C+ after τ.
Since it is included in D, one of the periods 2τ such as B + C
A signal of two periods τ is not needed. Therefore, as shown in the signal, the time axis of one period τ of the periods 2τ is expanded by twice, and the signals of the remaining period are removed to create a continuous signal. Since the time axis is doubled, the spectrum is compressed in half, and the highest frequency becomes 1/2 (fm+f _H /2). In a normal video system, since fm≫f _H , the highest frequency is approximated by 1/2 fm.

Note that the shift frequency in the frequency shift circuit 2 may be (2n+1)f _H /2 (n is an integer), but in order to minimize the bandwidth, n = 0 here.

FIG. 4 shows another example of a signal processing circuit on the recording side or transmitting side for obtaining the signal obtained by the first method, that is, the time axis expansion multiplexed signal (also referred to as the time axis expansion multiplexed signal). .

Here, the input component video signal is divided into two, one of the signals is delayed in time by τ in the delay device 11, and then in the time axis expansion circuit 12.
The time axis is set by 2 with the timing signal t which is generated every 2τ.
Forms a signal that is doubled and has a frequency bandwidth halved. At this time, information about half the period τ of the period 2τ disappears. Therefore, the other divided signal is supplied to the time axis expansion circuit 13, where the signal of the period lost in the time axis expansion circuit 12 when expanding the time axis by two times is expanded. Furthermore, the expanded signal is supplied to the frequency shift circuit 14, and the frequency is shifted by f _H /4, thereby creating a signal in a frequency interleaved relationship with the signal. Here, the time axis is expanded twice, so the horizontal scanning frequency is f _H /2. Therefore, the shift frequency becomes f _H /4. Therefore, a time-expanded multiplexed signal can be extracted by adding the signals whose time axis is doubled and which have a frequency interleaved relationship with each other using an adder 15.

Next, the operation of the circuit shown in FIG. 4 will be explained with reference to FIG.

As in the first embodiment, the highest frequency of the input component video signal is assumed to be fm. As shown in FIG. 5, the input signal is divided by time τ, as in the case of FIG. The spectrum is also the same as in FIG. The signal is delayed by τ in the delay device 11, and the time axis of one period τ of the periods 2τ is doubled by the time axis as shown in A, C, etc. in the time axis expansion circuit 12, and the signal of the remaining period is The highest frequency of the spectrum is fm/2. The signals are sent to B, D, . . . in the time axis expansion circuit 13.
, the time axis of the signal during the period removed by the signal is expanded by a factor of 2. Here, the time axis is expanded by a factor of 2, so the horizontal scanning frequency is
f _H /2. In the frequency shift circuit 14, the frequency is shifted by f _H /4, so the highest frequency is
It becomes fm/2+ _fH /4. By adding the signals, the adder 15 can obtain a time-axis expanded multiplexed signal as shown in the signal.

Note that the delay time τ of the delay device used in the present invention may be any arbitrary time, but if there is a correlation between the signals to be multiplexed, even if crosstalk occurs between the signals, it will be less noticeable. It is advantageous to not have it. In consideration of this, and from the viewpoint of ease of creating the timing signal t, it is preferable to select 1H, 1 field, or 1 frame as the delay time τ. In other words, the periodicity of a signal is determined by the signal itself and is independent of how it is extracted. That is, in the case of a video signal, since the video signal is made up of 30 frames of images per second, it has interrelationships between frames, fields, and lines. This signal is cut out for channel division, but the cutout period has no relation to the periodicity of the signal. Therefore, in principle, the above-mentioned τ period can be arbitrarily selected. However, in order to manufacture a frequency shift circuit in a small size using current technology, it is convenient to select τ to be an integral multiple or a fraction of H.

The signal obtained above is supplied to a narrowband VTR and recorded on videotape.

A specific example of the time axis expansion circuit used in the first and second embodiments of the present invention described above is shown in FIG.

In this time axis expansion circuit, S1 to S6 are switches, and their opening/closing timings are controlled as shown in FIG. The two τ period memories M1 and M2 are written every period τ by supplying a write pulse f ₁ via switches S1 and S2 and a read pulse f ₂ =f ₁ /2 via switches S3 and S4. As a result, reading is performed at half (1/2) the speed of writing, and the time axis of the signals at intervals of τ is doubled, making them continuous signals. The switch S5 distributes the input to the memories M1 and M2, and the switch S6 switches the output from the memories M1 and M2, both of which are controlled by the opening/closing timing shown in FIG.

As can be seen from the timing chart in FIG. 7, the time base expansion circuit also performs the operation of discarding the above-mentioned redundant information signals.

Next, a specific example of the frequency shift circuit will be explained.

In the case of Fig. 1, the shift frequency fs only needs to satisfy fs = (2n + 1) f _H /2 (n: integer) in order to create a frequency interleaving relationship (in the case of Fig. 4, it has already been reduced to 1/2). Since the band is compressed, the shift frequency fs is also 1/2 of the above value.) Here, in order to minimize the highest frequency of the frequency-shifted component video signal, n must be set to 0. Therefore, the frequency fs to be shifted by the frequency shift circuit is fs=f _H /
Set it to 2.

The frequency shift circuit that shifts one of the component video signals by the frequency fs can be constructed in various ways, such as having an image redirection mixer, but in Figure 8, a case using the phase shift method is considered. FIG. 9 shows an example configured using a band pass filter (BPF).

In the example of FIG. 8, the input video signal m(t) with the highest frequency fm is divided into two, and one of the two is directly applied to a balanced modulator or a double balanced mixer (hereinafter referred to as a double balanced mixer).
(abbreviated as DBM) 21, and the other is passed through a broadband phase shift circuit 22 to change its phase (-
The output m _h (t) shifted by τ/2) is supplied to the DBM 23. On the other hand, the signal corresponding to the shift frequency fs
fs(t) (=cos(f _H /2t)) is directly supplied to the DBM 21, and the phase is shifted by (-π/2) to the DBM 23 via the phase shift circuit 24 (=f _sh (t ))
and take the product between each input signal. That is,
The output of DBM21 is m(t)・fs(t)=m(t)・cos( _fH /2t)...(1). Also, the output of the DBM23 is m _o (t)・f _sh (t)=m _h (t)・cos (f _H /2t−π/2) = m _h (t)・sin (f _H /2t)... …(2) becomes. When the outputs of these DBMs 21 and 23 are subtracted by the subtracter 25, the output signal φ(t) is (1)
From formula and formula (2), φ(t)=m(t)cos( _fH /2t) _−mh (t)sin( _fH /2t)
...(3) becomes. Here, m _h (t) is the Hilbert transform of m(t),
f _sh (t) is the Hilbert transform of fs(t). Therefore φ(t)
becomes a signal obtained by shifting m(t) by f _H /2.

In the example shown in FIG. 9, the input video signal m(t) and carrier wave fc are supplied to the DBM 31, and the product of both inputs is m(t).
Find (t)・cosω _c t. The frequency spectrum of this DBM output is shown in FIG. 10A. This DBM output is supplied to the bandpass filter BPF32, and as shown in FIG. 10B or C, only the upper side wave USB or lower side wave LSB is passed through the BPF.
get the output. In the case of the upper side wave, this output can be expressed mathematically as m(t)·cosω _C t−m _o (t)·sinω _C t (4). Again, m _o (t) is the Hilbert transform output of m(t). Next, the BPF output and f _C + f _H /2 (for lower side wave) or f _C + f _H /2 (for upper side wave)
is supplied to the DBM 33 and the product of both is calculated. For example, in the case of the upper side wave, the product of equation (4) and (f _C +f _H /2 is taken, and the result is expressed by the following equation.

{m(t)・cosω _C t+m _o (t)sinω _C t} ・cos(ω _C 〜f _H /2)t = 1/2・[m(t)・cosf _H /2t−m _o (t)・sinf _H /2 + (m(t)・cos(2ω _C −f _H /2t −m(t)・sin(2ω _C −f _H /2t) ……(5) Therefore, the output of DBM33 is A signal obtained by frequency shifting the input video signal m(t) by f _H /2, a carrier 2f _C −f _H /2, and its upper and lower sidebands.The frequency spectrum of this signal is as shown in Figure 10D. But this signal is passed through low pass filter LPF
34, where only components up to frequency (fm+f _H /2) are passed through and taken out as a frequency shifted output. This output signal is expressed as m(t)·cosf _H /2t−m _o (t)·sinf _H /2 (6).

Next, an eleventh example of a signal processing circuit that restores the original component video signal by following the reverse of the signal processing process shown in FIG.

The time axis expansion multiplexed signal obtained by the present invention using the reproduced signal from the VTR or the received signal is supplied to the time axis compression circuit 41, where the time axis is compressed to 1/2 using the timing signal t. The output is divided into two, one signal is supplied to a comb filter 42 to extract the nf _H component, and then the signal is sent to a delay device 43.
to delay the time τ. The other signal is supplied to the comb filter 44 to obtain a spectrum component whose frequency is shifted by f _H /2 with respect to the above-mentioned extracted signal.
That is, the (n+1/2) f _H component is extracted and then frequency shifted by -f _H /2 in the frequency shift circuit 45 to return it to a signal having the same frequency spectrum as the television video signal. The outputs of the delay device 43 and the frequency shift circuit 45 are supplied to a signal switch 46, where the time τ is changed by the timing signal t〓.
Select and extract one of the output signals for each time. As a result, the signal switching device 46 can obtain the same signal as the original component video signal supplied to the signal processing circuit on the recording side or the transmitting side.

Another example of the signal processing circuit on the reproduction side or the reception side is shown in FIG. In this case, whereas FIG. 11 corresponds to FIG. 3, the signal processing process in FIG. 5 is performed in reverse.

Here, if we supply a time-axis expanded multiplexed signal such as a playback signal from a VTR to the comb filters 51 and 52, and look at the original component video signal,
Spectral components of n·f _H /2 and (n+1/2)·f _H /2 are respectively extracted for the signal whose time axis has been expanded twice. The output of the comb filter 51 is delayed by a time τ in a delay device 53 and then supplied to the time axis compression circuit 54. The output of the comb filter 52 is supplied to a frequency shift circuit 55, where f _H /
After frequency shifting by 4, the time axis compression circuit 56
supply to. The time axis compression circuits 54 and 56 receive the timing signal t and compress the time axis to 1/2. The outputs of these time axis compression circuits 54 and 56 are supplied to a signal switch 57, and here, at the timing of the timing signal t〓, the time axis compression circuit 54
and 56 outputs are taken out alternately.

Next, a comb filter used in the reproduction side or reception side device will be explained.

A comb filter generally delays a signal for a certain period of time and returns it to the original signal (signal that is not delayed).
This is a filter configured to add or subtract from .
As mentioned above, it is preferable that the signal to be calculated has a high correlation with the original signal, so from this point of view, the delay time should be one line, one field, or one line.
Preferably, it is a frame. In addition, in order to obtain images without deterioration for both moving images and still images, it is necessary to switch the delay time of the delay device used, such as using a line correlation type comb filter for moving images and a frame correlation type comb filter for still images. It is preferred to use an adaptive comb filter constructed as follows.

Here, we calculate the characteristics mathematically for a 3-line correlated comb filter.

An example of the configuration of such a filter is shown in FIG. Here, the input signal e ^jwt is input to a delay device 6 with a delay time τ _H = 1H.
1 and 62 sequentially, and also supplied to an adder 63. This adder 63 has the output of the delay device 62.
Also supply e ^jw(t-2 〓 ^H) , and the resulting addition output e ^jwt +
e ^jw(t-2 〓 ^H) is supplied to the adder 65 via the 1/2 amplitude suppression circuit 64. This adder 65 has a delay device 61.
^also supplies the output e ^{jw ( t- 〓 H ) of (t-} 〓 ^H) +cosωHe ^jw(t-2 〓 ^H) = (1+cosωτH)e ^jw(t- 〓 ^H) ……(7) is obtained. Furthermore, the output e ^jw(t- 〓 ^H) of the delay device 61 and the output 1/2 of the 1/2 circuit 64 {e ^jwt +e ^jw(t-2 〓 ^H) } are subtracted by the subtracter 66.
and its output signal G2 is G2=(1+cosωτH)e ^jw(t- 〓H ⁾ ...(8).

The frequency spectra of these output signals G1 and G2 are shown in FIGS. 14A and 14B, respectively.

In the signal processing circuits shown in FIGS. 11 and 12, the above-mentioned signals G1 and G2 can be made to correspond to extracted signals of a non-frequency-shifted signal and a frequency-shifted signal, respectively. Two comb filters in the processing circuit can be constructed from such a circuit as shown in FIG.

An example in which the time axis expansion multiplexing circuit according to the present invention described above is applied to a color television signal recording/reproducing system is shown in FIGS. 15 to 18.

FIG. 15 shows an example of a recording-side circuit of a recording/reproducing system that performs two-track recording by applying such a time-base expansion multiplexing circuit to each of a luminance signal and a chrominance signal. Here 4.5M from color TV camera
The three primary color imaging outputs R, G, and B in the Hz band are supplied to the matrix circuit 71 to generate luminance signals Y, 4.5 MHz band,
Obtain color difference signals B-Y and RY in the 1.5 MHz band. The color difference signals B-Y and R-Y are supplied to a time-base compression multiplexing circuit 72, where both signals are time-base compressed and multiplexed into a color signal C in a 3 MHz band. Furthermore, the luminance signal Y and the color signal C are supplied to recording signal processing circuits (ie, time axis expansion multiplexing circuits) 73 and 74, respectively, to which the present invention is applied. These circuits 73 and 74 are supplied with an f _H signal and a 2f _H signal, respectively, so that the bandwidth of 1/2 of the original signal is compressed, that is, 2.25 MHz and 2.25 MHz.
A 1.5 MHz time-domain stretched multiple luminance signal Y _T and a time-domain stretched multiple chrominance signal C _T are obtained. These luminance signals Y _T
and chrominance signal C _T are supplied to FM modulators 75 and 76, respectively, and their modulated outputs are recorded by video heads 77 and 78 on videotape 79 in two tracks.

FIG. 16 shows an example of a reproduction side circuit corresponding to the recording side circuit of FIG. 15. Two types of data recorded on two tracks on the videotape 79 shown in Figure 15.
The FM signals are extracted by video heads 81 and 82, respectively, and FM demodulators 83 and 8
4, the signals are demodulated into a time-axis expanded multiplexed brightness signal Y _T and a time-axis expanded multiplexed color signal _CT , and then supplied to reproduction signal processing circuits 85 and 86. These circuits 85 and 86 are also supplied with the f _H signal and the 2f _H signal, respectively, and the luminance signal Y with a bandwidth of 4.5 MHz and 3 MHz.
and form a color signal C. Furthermore, this color signal C is supplied to a time axis expansion and restoration circuit 87 to expand the time axis and reproduce the color difference signals BY and RY. Next, the luminance signal Y and color difference signals B-Y and RY are supplied to a matrix circuit 88, where three primary color signals R, G, and B in a 4.5 MHz band are obtained.

In the above, the parts constituting the present invention are:
These are recording signal processing circuits 73 and 74 shown in FIG. As mentioned above, by passing the recording signal processing circuits 73 and 74 through these recording signal processing circuits 73 and 74, the output side signal can be compressed to 1/2 of the bandwidth of both the luminance signal and the chrominance signal with respect to the input side signal. Note that in this example (Figs. 15 and 16), unlike the examples shown in Figs. 17 and 18, which will be explained next, a recording amplifier is used on the recording side, and a reproducing amplifier and a time base collector (TBC) are used on the reproducing side. has been omitted.

Next, FIGS. 17 and 18 show an example of a recording and reproducing system for recording and reproducing a color television signal on one track on a video tape by applying the present invention to the time axis compression multiplexing (TCI) system.

In this example, in the TCI method, the luminance signal is recorded on all lines, and the two types of color signals are time-axis compression multiplexed in line-sequential format and combined into one signal (TCI-LSC). Examples of the recording side circuit and the reproduction side circuit are shown in FIGS. 17 and 18, respectively.

In the recording side circuit shown in FIG. 17, three primary color signals R, G, and B from a color television camera are supplied to a matrix circuit 91 to produce a luminance signal Y and a color difference signal R-Y.
and B-Y. Furthermore, the color difference signal R-
Y and B-Y to the line sequential configuration circuit 92;
Here, the line-sequential color difference signal L _SC is used, and together with the luminance signal Y, TCI-LSC is generated in the TCI configuration circuit 93.
form a signal. This TCI-LSC signal is passed through a recording signal processing circuit 94 according to the present invention to compress its bandwidth to 1/2 to obtain a time-axis expanded multiplex signal TXP. This TXP signal is recorded on a video tape 98 via an FM modulator 95, a recording amplifier 96 and a video head 97.

In the playback side circuit shown in FIG.
The FM signal is amplified and waveform-equalized by a regenerative amplifier 99, and then demodulated by an FM demodulator 100 into a time-axis expanded multiplexed signal TXP. played like this
TXP signal is time base collector (TBC) 10
After the time axis error is corrected by 1, the signal is supplied to the reproduced signal processing circuit 102 to which the present invention is applied, and here
Regenerate TCI-LSC signal. This TCI-LSC signal is supplied to the TCI restoration circuit 103 to reproduce the luminance signal Y and line sequential signal _SC . Regenerated line sequential signal
The L _SC is supplied to a line sequential restoration circuit 104 to restore color difference signals RY and BY, and is supplied together with a luminance signal Y to a matrix circuit 105, where three primary color signals R, G, and B are restored.

According to this embodiment, there is an advantage that a color television signal can be recorded in the form of a narrow band signal on one track of a videotape.

[Effects of the Invention] As is clear from the above, according to the method of the present invention, the component video signal is divided into two parts and the frequency interleave relationship is established between them by focusing on the spectral structure peculiar to the component video signal of the color television signal. By creating, multiplexing, and doubling the time axis, the video signal bandwidth can be reduced by 1/2.
It can be compressed into 2.

Furthermore, during such compression, adjacent signals of respective time periods of the input component video signals are made to be simultaneous signals, so that even if crosstalk occurs during multiplexing, it is not noticeable.

Furthermore, when recording in the form of an FM signal as in a VTR, the demodulation noise component in the FM signal is proportional to the 3/2 power of the band. Therefore, in a VTR that uses FM recording, the video signal bandwidth is halved.
This means that the S/N of the reproduced video signal is
This means an improvement of 9dB. Since there is a relationship of S/N∝W ^1/2 between S/N and recording track width W, if this S/N improvement is used to improve recording density, it is possible to record at eight times the recording density. become.
In addition, if we allocate this to smaller head drums, lower relative speeds between the tape and the head, etc., it is possible to
Achieve miniaturization. be able to.

Furthermore, since the time-axis expanded multiplexed signal obtained by the present invention maintains the general properties of a television video signal, such as the amplitude component exponentially attenuating in the high range, the circuit for recording or transmission is There are some advantages to keeping the traditional way of thinking.

The system of the present invention can be applied not only to the recording and playback of television video signals, but also to the transmission of component video signals when, for example, a temporary relay unit (FPU) connects the broadcast site and the studio during outdoor broadcasting of television programs. Of course, it can also be used effectively.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a signal processing circuit on the recording side or the transmitting side in the present invention.
Figure 2 is a spectrum diagram of the luminance signal, Figure 3 is the spectrum diagram of the luminance signal.
An explanatory diagram showing a comparison of the transition on the time axis and the transition on the frequency spectrum for each part of the signal in the figure, and FIG. 4 is a block diagram showing another embodiment of the signal processing circuit on the recording side or the transmitting side in the present invention. Diagram, 5th
The figure is an explanatory diagram that compares the transition on the time axis and the transition on the frequency spectrum for each part of the signal, Figure 6 is a circuit diagram showing an example of a time axis expansion circuit, and Figure 7 is a diagram of each of the switches. 8 is a block diagram showing an example of a frequency shift circuit; FIG. 9 is a block diagram showing another example of a frequency shift circuit; FIG. 10 is a timing chart showing opening/closing timing.
Figures A to D are frequency spectrum diagrams of the various signals in Figure 9, Figures 11 and 12 are block diagrams showing two examples of signal processing circuits on the reproduction side or reception side, and Figure 13 is a three-line correlation comb. Block diagram showing an example of a type filter, No. 14A and B are its G1
15 and 16 are block diagrams showing the recording side and reproduction side circuits, respectively, in an example of the recording/reproducing system. Figures 17 and 18 are the frequency spectrum diagrams of other recording/reproducing systems. FIG. 4 is a block diagram showing a recording side circuit and a reproduction side circuit, respectively, in an example. 1, 11... Delay device, 2, 14... Frequency shift circuit, 3, 15... Adder, 4... Time axis expansion circuit, 12, 13... Time axis expansion circuit, M1, M
2...τ period memory, S1 to S6... switch,
21...Double balanced mixer (DBM), 22...Broadband phase shift circuit, 23...DBM, 24...
Phase shift circuit, 25... Subtractor, 31, 33...
...DBM, 32...Band pass filter, 34...
...Low pass filter, 41...Time axis compression circuit, 4
2, 44... Comb filter, 43... Delay device,
45... Frequency shift circuit, 46... Signal switcher, 51, 52... Comb filter, 53... Delay device, 54, 56... Time axis compression circuit, 55...
Frequency shift circuit, 57... Signal switch, 61,
62...Delay device, 63, 65...Adder, 64...
1/2 amplitude suppression circuit, 66...subtractor.

Claims (1)

[Scope of Claims] 1. Sequentially extract signals of a predetermined τ period from the original component video signal as units, and two adjacent signals among the sequentially extracted signals.
After changing these signals into two-channel signals that occur simultaneously, the two-channel signals are multiplexed while maintaining a mutual frequency interleaving relationship to create a single-channel signal, and then the time axis is expanded to a signal with a 2τ period. Alternatively, the modified two-channel signals are time-expanded into signals with a period of 2τ, and then multiplexed while maintaining the frequency interleaving relationship to form a single-channel signal, so that the video signal bandwidth is equal to the original component. A band compression method for component video signals characterized by performing band compression on a single channel signal, which is approximately 1/2 of the video signal.