JPH0752945B2 - Transmission system of television signal - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a transmission system of television signals, and more particularly to a transmission system of signals suitable for a high-definition television compatible with existing televisions.

[Background of the Invention]

As a high-definition television that realizes high image quality and high definition while maintaining the same required signal bandwidth and signal form as the current television, a system that is completely compatible with the current standard has been proposed. "Proposal of high-definition TV system with perfect communication""Communication newsletter CS83-61, July 1983".

FIG. 1 is a diagram showing a signal spectrum in the “time-vertical” frequency domain in the above-mentioned existing method. In the above existing method, the color signal C is the color subcarrier f _SC (± 15 Hz, 525/4 lines)
The high-definition information Y _H ′ is a subcarrier μ ₀ (± 15 Hz, ± 525/4
Book) is amplitude-modulated. As a result, as shown in FIG. 1, the color signal C has a signal spectrum in a dotted area and the high-definition information Y _H ′ has a signal spectrum in a shaded area. However, as is apparent from FIG. 1, there is an overlap area between the dotted areas and the hatched area, and crosstalk occurs in this area, and the color signal C and the high-definition information Y _H ′ are generated on the image receiving side. Cannot be accurately demodulated. In order to avoid such crosstalk (crosstalk), in the above-mentioned existing method, high-definition information Y _H ′
Signal spectrum must be restricted to the 1st and 3rd quadrants, and as shown in the hatched area in FIG.
It is necessary to limit the band of the vertical frequency component of Y _H ′ to 0 to 525/4. Therefore, for example, high-definition information with a low vertical frequency component such as vertical stripes can be transmitted, but high-definition information with a high vertical frequency component such as diagonal stripes cannot be transmitted because it is subject to band limitation. I have a problem.

[Object of the Invention]

An object of the present invention is to provide a transmission system of a high definition television signal capable of transmitting high definition information having a high vertical frequency component.

[Outline of Invention]

In the present invention, the subcarrier μ ₀ used for multiplexing the high-definition information Y _H ′ has a time frequency f of f ≠ 0 Hz and f ≠ ± 15 _H.
Use the z component. That is, unlike the above-described existing method, the signal spectrums of the color signal C and the high-definition information Y _H ′ are arranged in the regions having different time frequencies f. Therefore, in the present invention, the signal spectrum of the color signal C and the signal spectrum of the high-definition information Y _H ′ are separated on the time-frequency axis, so that crosstalk as in the above-described method does not occur. . Therefore, in the present invention, band limitation of the vertical frequency component is unnecessary, and high-definition information Y _H ′ having a high vertical frequency component can also be transmitted. Needless to say, the condition of f ≠ 0 Hz is for avoiding crosstalk with the luminance signal Y.

FIG. 2 is a diagram showing an example of a signal spectrum in the “time-vertical” frequency domain of the transmission system according to the present invention. In the example shown in FIG. 2, the subcarrier μ ₀ is “time-vertical”.
It is located at two points (± 7.5Hz, 0 line) in the frequency domain. That is, the time frequency f is f = ± 7.5 Hz, and the time frequency f satisfies the conditions of f ≠ 0 Hz and f ≠ ± 15 Hz. As is apparent from FIG. 2, the color signal C has its signal spectrum at the time frequency f of f = ± 15 Hz, and the high-definition information Y _H ′ at the time frequency f of f = ± 7.5 Hz. There is only a signal spectrum. Therefore,
The areas where the color signal C exists and the shaded areas where the high-definition information Y _H ′ does not overlap, and crosstalk does not occur. Therefore, it is not necessary to limit the band of the vertical frequency component of the high definition information Y _H ′, and the vertical frequency component is 0
Up to 525/2 lines can be transmitted. That is, the present invention also enables transmission of 525/4 to 525/2 vertical frequency components that cannot be transmitted by the above-described method. As a result, it becomes possible to transmit high-definition information having a high vertical frequency component such as an oblique pattern.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG. This embodiment is an example of the transmission side and shows multiplexing of high-definition information Y _H ′. In this case, the carrier wave μ ₀ used for multiplexing is “time −
This is an example having a component at = ± 7.5 Hz in the "vertical" frequency domain. As high-definition information, the luminance signal high frequency component Y _H (4.
2MHz or more). Further, FIG. 4 is a structural example of a high-definition television signal transmitted in this embodiment, and FIG. 5 is a subcarrier μ as shown in FIG. 2 in the present invention.
The phase relationship in the “time-vertical” region when ₀ is the time frequency f = ± 7.5 Hz and the vertical frequency ν = 0 is shown.
In FIG. 5, the subcarrier μ ₀ has a phase in the unit of 4 field periods in the time direction ... ψ ′, ψ ′ + π,
ψ ′, ... That is, the phase is inverted every 4/60 seconds in units of 4 field periods, that is, the signals have the same phase every 8/60 seconds. Therefore, the time frequency component of the subcarrier μ ₀ is f = 1 / (8/60) = 60/8 = 7.5 Hz. On the other hand, in FIG. 5, the subcarrier μ ₀ always has the same phase in the vertical direction, and therefore the vertical frequency component of the subcarrier μ ₀ is ν = 0.

In FIG. 3, the high-pass filter 1 extracts the component of 4.2~8.4MHz as a luminance signal high-frequency component Y _H. Then, in the modulator 2, Y _H is a subcarrier μ having a frequency of 8.4 MHz.
_The carrier suppression amplitude modulation is performed at ₀ , and the lower band component is taken out by the low pass filter 3 to obtain the high bond fine information Y _H ′ whose frequency is shifted to the 0 to 4.2 MHz band. The phase of the carrier wave μ ₀ is controlled by the phase control circuit 4 in the time direction as shown in FIG. 5, for example. That is, as described above, the phase control is performed so that the phase of the subcarrier μ ₀ changes in the time direction in units of four field periods, ..., ψ ′, ψ ′ + π, ψ ′ ,. By this operation, high definition information
In Y _H ′, the signal components are arranged at the positions shown in FIG. 2 in the “time-vertical” frequency domain.

On the other hand, the luminance signal and the color difference signals I and Q are transmitted by the encoder circuit 5 to the luminance signal Y having the same form as the current NTSC signal,
And the color signal C. The color subcarrier is shown in FIG.
f _SC time frequency f is f = ± 15Hz, vertical frequency ν is ν = 52
The phase relationship in the "time-vertical" area for 5/4 lines is also displayed. In FIG. 5, the color subcarrier f _SC has a phase in units of two field periods in the time direction.
It changes as ψ, ψ + π, ψ, .... That is, the phase is inverted every 2/60 seconds in units of 2 field periods, that is, 4 /
Signals with the same phase every 60 seconds. Therefore, the time frequency component of the color subcarrier f _SC is f = 1 / (4/60 = 60/4 = 15 Hz. On the other hand, in FIG. 5, the color subcarrier f _SC is one scan line in the vertical direction. The phase is in units of ..., ψ, ψ +
It changes as π, ψ, .... That is, the phase is inverted for each scanning line, and the signals have the same phase for every two scanning lines. Therefore, the vertical frequency component of the color subcarrier f _SC is ν = 525/4.

In the multiplexing circuit 6 of FIG. 3, the high-definition information Y _H ′ is multiplexed with the luminance signal Y and the chrominance signal C to form and transmit the high-definition television signal according to the present invention.

This high-definition television signal has a signal band of 4.2 MHz and the signal form conforms to the current NTSC signal, and thus is compatible with the current system.

At the time of reproducing the high-definition information Y _H ′ on the receiving side, at least 2 pieces of phase information of the carrier wave are set in order to determine the phase of the carrier wave.
Multiplex once per frame. This phase information is, for example,
It can be multiplexed in a vertical blanking period or the like.

Next, FIG. 6 shows an embodiment of reproducing high-definition information on the receiving side. One of the high definition television signals is delayed by the frame delay circuit 7 for two frames. Then, Y _H separating the 'separation circuit 8, a high-definition information Y _H by taking the difference between the no delay high-definition television signals'. This is because in a high-definition television signal without delay and a signal delayed by two frames, the color signal C has the same phase and the high-definition information Y _H ′ has the opposite phase, as shown in FIG. . Therefore, the high-definition information Y _H ′ can be separated by taking the difference between the two.

The arithmetic circuit 9 subtracts the Y _H ′ component from the high definition television signal to obtain the luminance signal Y and the color signal C. This signal is demodulated by the decoder circuit 13 into color difference signals I and Q and a luminance signal Y.

On the other hand, the high-definition information Y _H ′ is synchronously detected by the synchronous detection circuit 10 with the subcarrier μ ₀ having the same phase as the transmitting side, and the high-pass filter is obtained.
At 12, the components in the band 4.2 to 8.4 MHz are extracted to reproduce the original luminance signal Y _H ′. At the time of synchronous detection, the phase control circuit 11 controls the phase of μ ₀ based on the multiplexed phase information, and reproduces the subcarrier μ ₀ necessary for synchronous detection.

The high frequency component Y _H is added to the luminance signal Y by the adder circuit 14, and 0 to 8.
Demodulate as a 4MHz luminance signal.

〔The invention's effect〕

According to the present invention, high-definition information having a high vertical frequency component can be sufficiently transmitted, and there is an extremely effective effect in improving the image quality and definition of a high-definition television.

In the embodiment, the high-definition information Y _H ′ is multiplexed in the ₀ to 4.2 MHz band, but it is 4.2 to 6.4 MH by selecting μ ₀ = 2.2 MHz, for example.
It is also possible to multiplex the high-frequency component Y _H of z in the 2.0 to 4.2 MHz band as high-definition information Y _H ′. In this case, interference when a high-definition television signal is received by the current receiver can be reduced.

In the embodiment, the high frequency component of the luminance signal is used as the high definition information. However, for example, the G signal of the three primary color signals,
Alternatively, the same effect can be obtained by using the high frequency component of the color difference signal I or Q or a combination thereof.

Furthermore, since the components of high-definition information are reduced due to the storage effect of the image pickup tube during moving images, in transmission, high-definition information is multiplexed and transmitted and reproduced only during still images or in the case of slow motion. It is also possible to perform a so-called motion adaptation operation. In this case, it is possible that the transmitting side sends the presence or absence of high-definition information multiplexing as mode information together with the position information, and the receiving side controls the reproduction of the high-definition information according to the mode information.

Further, in order to distinguish the high-definition television signal of the present invention from the current NTSC signal, identification information is added to the transmitted high-definition television signal, and if there is identification information on the receiving side, Y _H It is also possible to perform the reproduction process of '. In this case, it goes without saying that the identification information may include the above-mentioned phase information and mode information.

Further, in the embodiment, the case where the time frequency component of the subcarrier μ ₀ is f = ± 7.5 Hz has been described, but subcarriers of other time frequency components (= 0, ± 15 Hz are excluded) may be used. Not to mention possible.

[Brief description of drawings]

FIG. 1 shows the signal spectrum of the existing system in the “time-vertical” frequency domain, FIG. 2 shows the signal spectrum in the “time-vertical” frequency domain of the transmission system of the present invention, and FIG. 3 shows the case of implementing the present invention. FIG. 4 is a diagram showing a configuration of an embodiment of a transmission unit, FIG. 4 is a frequency spectrum diagram for explaining the operation of FIG. 3, FIG. 5 is a diagram showing phases of scanning lines, and FIG. It is a figure which shows the principal part structure of one Example of a receiver in a case. 1,12 ...... High pass filter, 2 ...... Modulator, 3 ...... Low pass filter, 4,11 ...... Phase control circuit, 5 ...... Encoder circuit, 6 ...... Multiplex circuit, 7 ...... Frame delay circuit, 8
...... Y _H 'separator, 9 ...... subtraction circuit, 10 ...... synchronous detection circuit, 13 ...... decoder circuit.

Claims (2)

[Claims] 1. An image signal is divided into a low band component below a predetermined signal band defined by the television standard and a high band component exceeding the predetermined signal band, and the high band component is frequency-shifted using a subcarrier μ _0. predetermined signals into high-resolution information in the band, the transmission system of the television signal for transmitting the low-frequency component of the high-resolution information and the image signal frequency-multiplexed, as the sub-carrier mu _0, "time by A television characterized in that a time frequency component other than f = 0 Hz and f = ± 15 Hz in the "vertical" frequency domain is used, carrier suppression amplitude modulation is performed in the high frequency component, and conversion is performed into the high definition information. Signal transmission method. 2. The time frequency component of the subcarrier μ ₀ is f =
The television signal transmission system according to claim 1, wherein the transmission frequency is ± 7.5 Hz.