JPH082103B2 - High definition television - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-definition television compatible with a current television, and particularly to a high-definition television obtained by frequency-shifting a high-definition signal. The present invention relates to a high definition television which receives a Johns signal.

[Conventional technology]

As one example of applying the frequency shift of the image signal, as a method for transmitting a high-resolution image, which has compatibility with the current television and can be received by a dedicated receiver, Japanese Patent Application No. 58-044238. The ones described in the issue are known.
In this method, the high-definition signal of the image signal is frequency-converted into the signal band of the current television by frequency shifting, frequency multiplexing is performed, and the high-definition image is transmitted in the same band as the current television signal.

[Problems to be solved by the invention]

In the compatible high-definition television, the superposed high-definition signal component appears as an interfering component when received by a current television, resulting in image quality deterioration. In order to reduce this interference, the multiplex level of the high-definition signal should be reduced, or, as shown in FIG.
There is known a method of frequency shift such as superimposing as μ ₀ -fmin on the high frequency band of the current television signal.

The frequency shift is realized by amplitude modulation with the subcarrier μ ₀ . Then, the frequency-shifted signal is demodulated as an original high-definition signal by synchronous detection on the receiving side. However, in the frequency shift shown in FIG. 2, since the frequency of the subcarrier μ ₀ used is high, it is not possible to transmit the μ ₀ component in the current transmission system, so that synchronous detection on the receiving side becomes impossible. There was a problem that became.

An object of the present invention is to provide a high-definition television which enables the transmission of information of the subcarrier μ ₀ even in the existing transmission system and has less interference with the existing television.

[Means for solving problems]

The above object is achieved, instead of the subcarrier mu _0, mu ₀ and 'make, the transmission this mu _0' specific pseudo subcarrier mu ₀ of the frequency of 1 / n with a phase relationship using a subcarrier information ,
On the receiving side, this is achieved by reproducing the subcarrier μ ₀ based on this μ ₀ ′ and using it for synchronous detection.

〔Example〕

Hereinafter, the present invention will be described with reference to examples. FIG. 1 shows an embodiment of the present invention in the transmitting section. (A) is a structure of a transmission part, (b) is a frequency characteristic diagram for operation | movement description. In this embodiment, the high frequency component of the luminance signal (4.2 MHz or more) is used as the high definition signal of the image signal, and the subcarrier used in the frequency shift is 2.2 fsc (fs
c is equivalent to the color subcarrier of the current television).

The luminance signal Y from the HPF circuit 1, to separate the above components 4.2MHz as a high-definition signal Y _H. This Y _H signal is subjected to carrier suppression amplitude modulation with the subcarrier μ ₀ (= 2,2fsc) in the modulator 2, and the BPF circuit 3 performs 2.2fsc-6MHz-
The high-definition signal component Y _H ′ that is frequency-shifted to 2.2 fsc-4.2 MHz is extracted.

On the other hand, the luminance signal Y _L whose band is limited (4.2 MHz) by the LPF circuit 4 is delay-adjusted by the delay circuit 5. Further, the color difference signals I and Q are modulated by the quadrature modulation circuit 6 into C signals of the current television.

On the other hand, the subcarrier μ ₀ used for frequency shifting is frequency 1
In the / n circuit 8, a pseudo subcarrier μ ₀ ′ of μ ₀ / n (μ ₀ ′ = 0.55 fsc because n = 4 is taken in the embodiment).

The mixing circuit 7 adds the color signal C and the high-definition signal Y _H ′ to the Y _L signal, and also adds a synchronizing signal, a burst signal and the like. Further, the information of the pseudo subcarrier μ ₀ ′ is added to form a high definition television signal. To add μ ₀ ′, for example, μ ₀ ′ information may be added to the image signal portion of the last scanning line in the odd field.

The subcarrier μ ₀ and the pseudo subcarrier μ ₀ ′ to be transmitted are set to have a specific phase relationship as shown in FIG.

Note that the phase of the subcarrier μ ₀ used for frequency shift is inverted every line and every frame as described in Japanese Patent Application No. 58-044238, and the point of the same phase falls in each field. Have. Therefore, the phase control circuit 9 inverts the phase by π for each field to generate μ ₀ that satisfies the above-mentioned phase relationship.

Next, FIG. 4 shows an embodiment of the present invention on the image receiving side.

The high-definition television signal in which the color signal C and the high-definition signal Y _H ′ are superimposed on the luminance signal Y _L is respectively separated by the separation circuit 10.
It is separated into Y _L signal, C signal, and Y _H ′ signal. At the time of this separation, it is preferable to perform separation processing with less crosstalk by so-called motion-adaptive separation in which the separation characteristic is changed according to the movement of the image.

The color signal C is subjected to quadrature synchronous detection by the color signal demodulation circuit 11 and demodulated into the original color difference signals I and Q.

On the other hand, the high-definition signal Y _H ′ is synchronously detected by the Y _H synchronous detection right circuit 12 with the subcarrier μ ₀ reproduced on the receiving side as described later, and the BPF circuit 13 increases the original frequency band. The fine signal Y _H is demodulated.

Also, a Y _L signal whose delay is adjusted by the delay circuit 14,
The demodulated _YH signal is added by the adder circuit 15 to demodulate the luminance signal Y.

On the other hand, the subcarrier reproducing circuit 16 generates a reference subcarrier μ ₀ ″ whose phase matches that of the added pseudo subcarrier μ ₀ ′. From this μ ₀ ″, a frequency n-fold circuit is generated.
At 17, the subcarrier μ ₀ having the phase relationship as shown in FIG. 3 is reproduced. This μ ₀ is, as described above, the phase control circuit 9
Phase inversion is performed for each field to reproduce a desired subcarrier required for synchronous detection.

〔The invention's effect〕

According to the present invention, it is possible to realize a compatible high-definition television with less interference with the current television, and thus it is very effective in improving the definition of an image.

Clearly, embodiments of the invention are both analog and digital.

Further, in the embodiment, the case where the subcarrier μ ₀ is 2.2 fsc has been described as an example, but it is obvious that the present invention can be applied to μ ₀ different from this.

Furthermore, it is apparent that the high-definition signal can be applied to a color signal or the like in addition to the luminance signal.

The pseudo subcarrier μ ₀ ′ is 1 / n of the original subcarrier μ ₀ , and n
Is an integer satisfying the relation of μ ₀ ′ <4.2 MHz.
It should be noted that if n is appropriately selected, the subcarrier μ ₀ can be reproduced even when n is not an integer. For example, subcarrier μ ₀
This is a case where n = 11/3 is selected for (= 2.2fsc) and the pseudo subcarrier μ ₀ ′ (= 0.6fsc) is transmitted. At this time, the subcarrier μ ₀ and the pseudo subcarrier μ ₀ ′ to be transmitted are set in a specific phase relationship with the color subcarrier fsc as shown in FIG.

Play subcarriers mu ₀ is easily performed by sampling a pseudo subcarrier mu ₀ 'in Figure 5 to show such fsc synchronization points a, b, c, d, e. That is, the received pseudo subcarrier μ
₀ ′ is converted into a digital signal sequence at a frequency that is an integral multiple of the color subcarrier fsc. Using this digital signal sequence, the data values at the points of the fsc cycle of a, b, c, d, and e as shown in the figure are compared for the transmitted pseudo subcarrier μ ₀ ′. , to determine the phase of the pseudo subcarrier mu ₀ ', determines the subcarrier mu ₀ phase this as a reference. For example, when the sample value at point a is X ₁ , the point b is X ₂ , the point c is X ₃ , the point d is X ₄ and the point e is X ₅ , then X ₁ <X ₃ , X ₁ <X ₅ , The phase of the pseudo subcarrier μ ₀ ′ at the point a where the relationships of X ₁ > X ₂ and X ₁ > X ₄ are established is determined to be 0. Then, using this phase as a reference phase, the subcarrier μ ₀ is reproduced. To reproduce the subcarrier μ ₀ , the phase of the phase information circuit that reproduces the phase information in 4fsc20 clock cycles is set to the initial value 0.
And the subcarrier μ ₀ corresponding to this phase information is created (when digital signal processing is performed at 4 times the color subcarrier fsc). In this example, reproduction of the color subcarrier fsc on the image receiving side is premised, but in a compatible high-definition television, the superposition of color signals is exactly the same as that of the current television, and bursts are generated for each scanning line. Since the signals are also superimposed, there is no problem in reproducing the color subcarrier on the image receiving side.

[Brief description of drawings]

1 and 4 are configuration diagrams of an embodiment of the present invention, FIG. 2 is an example of frequency shift, and FIGS. 3 and 5 are subcarrier μ ₀ and subcarrier μ to be transmitted. It is a phase relationship diagram of ₀ '. 1 ... HPF circuit, 2 ... modulator, 3 ... BPF circuit, 4 ...
LPF circuit, 5 ... Delay circuit, 6 ... Quadrature modulation circuit, 7 ...
… Mixing circuit, 8 …… frequency 1 / n circuit, 9 …… phase control circuit, 10 …… separating circuit, 11 …… color signal demodulating circuit, 12 …… Y
_H synchronous detection circuit, 13 ... BPF circuit, 14 ... delay circuit, 15 ...
… Addition circuit, 16 …… Subcarrier recovery circuit, 17 …… Frequency n
Double circuit.

Claims (2)

[Claims] [1 claim: a luminance signal Y _L, and the color signal C, and the second high-definition signal Y _H 'in which the first high-definition signal Y _H and the frequency conversion using the subcarrier mu _0, the subcarrier mu _In a high-definition television receiving a high-definition television signal composed of a pseudo subcarrier μ ₀ ′ obtained by multiplying ₀ by 1 / n (n is an integer), the received high-definition television signal is converted into the luminance signal Y.
_L , means for separating the color signal C, and the second high-definition signal Y _H ′; means for multiplying the pseudo subcarrier μ ₀ ′ by n to create the subcarrier μ ₀ ; Means for demodulating the high-definition signal Y _H ′ using the subcarrier μ ₀ to generate the first high-definition signal Y _H. 2. The high definition television according to claim 1, wherein the first high definition signal Y _H is a high frequency component of a luminance signal.