JPS6236992A - Transmission system for television signal - Google Patents

Abstract

PURPOSE:To facilitate the transmission of a high-definition TV signal compatible with the existing TV signal by using carrier waves having frequency components other than OHz and 15Hz in the time versus vertical frequency region in the carrier waves used for multiplexing high-definition information. CONSTITUTION:Components of 4.2-8.4MHz are extracted by a HPF 1 as a luminance signal high-frequency component YH. Then the signal YH is subjected to carrier suppression amplitude modulation by using a carrier mu0 whose frequency is 8.4MHz at a modulator 2 and a LPF 3 extracts the side band component to obtain high-definition information YH' frequency-shifted at 0-4.2MHz band. On the other hand, a luminance signal Y and a chrominance signal C the same mode as those of the existing NTSC signal are formed at an encoder 5 from a luminance signal I and a color difference signal Q. A multiplex circuit 6 multiplexes the information YH' on the signals Y and C to constitute a high- definition TV signal, which is sent. Since the high-definition TV signal complies with the existing NTSC signal in both the signal band and the signal form, the system has the compatibility with the existing system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a television signal transmission system, and particularly to a signal transmission system suitable for high-definition television that is compatible with current televisions.

[Background of the invention]

High-definition television (extended definition
ded Definition TV), a method that is completely compatible with the current standard has been proposed (Fukunuki et al.
High-definition TV system with complete communication performance (%) This system transmits television signals horizontally and vertically.

When viewed in terms of the three-dimensional frequency of time, as shown in Figure 1, high-definition information YR' is located in the 1st and 3rd quadrants of the 1 hour-vertical frequency domain, which is not used in current television signals (NTSC signals). multiplex and transmit.

However, the color signal C of the current television signal is 1 hour -
Vertical” frequency domain second . In order to avoid crosstalk with the high-definition information YI' existing in the fourth quadrant and multiplexed with the color signal C, it is necessary to band-limit the high-definition information YII' to 525/4 vertical frequencies. For this reason, for example, high-definition information with a low vertical frequency component, such as a pattern with fine vertical stripes, can be transmitted, but high-definition information with a high vertical frequency component, such as a pattern with diagonal stripes, cannot be transmitted due to band restrictions. There is.

[Purpose of the invention]

The purpose of the invention is to be fully compatible with current standards and to
An object of the present invention is to provide a high-definition television signal transmission system that can also transmit high-definition information with high vertical frequency components.

[Summary of the invention]

In the present invention, in the "time-vertical" frequency domain, high-definition information Y, /
multiplex. That is, in the present invention, high-definition information Y, I'
carrier wave μ used for multiplexing. In the "time-vertical" frequency domain, components of f≠OHz and f≠±15 Hz are used. For example, in the 1 hour-vertical frequency domain in FIG. 2, the carrier wave μ. has a time-frequency component of f=±7.5Hz). For this reason, high-definition information Y
When performing 8' multiplexing, it becomes possible to multiplex high components up to the band limit in the vertical frequency direction. As a result, it becomes possible to transmit high-definition information with high vertical frequency components, such as diagonal patterns.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. This embodiment is an example of the transmitting side, and shows multiplexing of high-definition information.

In this case, the carrier wave μ used for multiplexing. is an example having a component at f=±7.5Hz in the 1 hour-vertical" frequency domain. Note that the high-definition information is the luminance signal high-frequency component YIl.
(4.2MHz or higher). Further, FIG. 4 shows an example of the configuration of a high-definition television signal transmitted in this embodiment, and FIG. 5 shows a carrier wave μ in the 1-hour-vertical region.

shows the phase relationship of

Bypass filter 1 removes brightness signal high-frequency components Y, I
Components of 4.2 to 8.4 MHz are extracted. Then, Yn is used as a carrier wave μ having a frequency of 8.4-MHz in the modulator 2. By carrying out carrier wave suppression amplitude modulation and extracting this lower sideband component by the low-pass filter 3, 0 to 4.
High-definition information YIl' frequency shifted to 2MHz band
get. Note that the carrier wave μ. is determined by the phase control circuit 4,
For example, as shown in FIG. 5, the phase is controlled in the time direction.

By this operation, signal components of the high-definition information Yl,' are arranged at positions as shown in FIG. 2 in the "time-vertical" frequency domain.

On the other hand, the encoder circuit 5 generates a luminance signal Y and a chrominance signal C having the same format as the current NTSC signal from the luminance signal and the color difference signals I and Q. In addition, the phase relationship of the color subcarrier J used in FIG. 5 is also displayed.

In the multiplexing circuit 6, high-definition information YII' is multiplexed on the luminance signal Y and the chrominance signal C to form and transmit a high-definition television signal according to the present invention.

This high-definition television signal has a signal band of 4.2MHz.

Since the signal format also conforms to the current NTSC signal, it is compatible with the current system.

Note that, in order to determine the phase of the carrier wave when reproducing the high-definition information Y□' on the receiving side, the phase information of the carrier wave is multiplexed at least once every two frames. This phase information can be multiplexed, for example, during the vertical blanking period.

Next, FIG. 6 shows the actual flow of reproduction of high-definition information on the receiving side. One of the high-definition television signals is delayed by two frames by the frame delay circuit 7.

Then, the YH' separation circuit 8 separates the high-definition information Y□' by taking the difference from the high-definition television signal without delay.

In other words, in a high-definition television signal without delay and a signal delayed by 2 frames, the color signal C is in the same phase as shown in Figure 5, and the high-definition information YII' is in reverse phase. . Therefore, high-definition information YH' can be separated by taking the difference between the two.

The arithmetic circuit 9 subtracts the YII' component from the high-definition television signal to obtain a luminance signal Y and a color signal C. This signal is converted into one color difference signal I,Q by the decoder circuit 13.
and demodulated into a luminance signal Y.

On the other hand, the high-definition information YIl' is generated by the synchronous detection circuit 10, which uses a carrier wave μ having the same phase as that on the transmitting side. The signal is synchronously detected by the bypass filter 12, and components in a band of 4.2 to 8.4 MHz are extracted to reproduce the original luminance signal YII. Note that during synchronous detection, the phase control circuit 11
Deμ. The carrier wave μ required for synchronous detection is
. Play.

A high frequency component Yl is added to the luminance signal Y by an adder circuit 14,
It is demodulated as a luminance signal of 0 to 8.4 MHz.

〔Effect of the invention〕

According to the present invention, transmission of a high-definition television signal that is completely compatible with current television signals can be realized with an in-tube configuration, and is extremely effective in improving image quality and definition.

In addition, in the embodiment, high-definition information Y is provided in the 0 to 4.2 MHz band.
I? ′ was multiplexed, but for example μ. = 2.2 MHz, the high frequency components Y and I of 4.2 to 6.4 MHz are reduced to 2.
．． It is also possible to multiplex high-definition information Y□' in the 0 to 4.2 MHz band. In this case, interference when high-definition television signals are received by current receivers can also be reduced.

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

Furthermore, when moving images, the amount of high-definition information decreases due to the accumulation effect of the image pickup tube, so when transmitting high-definition information, high-definition information is multiplexed and transmitted only for still images or slow movements. It is also possible to perform motion-adaptive operations. In this case, it is also possible for the transmitting side to send mode information indicating whether high-definition information is multiplexed together with position information, and for the receiving side to control reproduction of the high-definition information according to the mode information.

In addition, in order to distinguish between the high-definition television signal of the present invention and the current NTSC signal, identification information is added to the high-definition television signal to be transmitted, and if the receiving side has the identification information, it is recognized as a YII' high-definition television signal. It is also possible to perform regeneration processing. In this case, it goes without saying that the above-mentioned phase information and mode information may also be included in the identification information.

Furthermore, in the embodiment, the carrier wave μ. The time-frequency component of is f
= ±7.5 Hz, but it goes without saying that it is also possible to use carrier waves of other time-frequency components (Cf = O, excluding ±15 Hz).

[Brief explanation of drawings]

FIG. 1 shows the signal spectrum of the parent system in the "time-vertical" frequency domain, FIG. 2 shows the signal spectrum of the transmission method in the present invention in the "time-vertical" frequency domain, and FIG. 3 shows the signal spectrum of the transmission method according to the present invention in the "time-vertical" frequency domain. FIG. 4 is a frequency spectrum diagram for explaining the operation of FIG. 3; FIG. 5 is a diagram showing the phase of a scanning line; FIG. 6 is a diagram showing the configuration of an embodiment of the transmitting section; FIG. FIG. 2 is a diagram illustrating a main part configuration of an embodiment of a receiver in the case of the present invention. 1, ] 2... Bypass filter, 2... Modulator, 3
...Low pass filter, 4, 11... Phase control circuit, 5... Encoder circuit, 6... Multiplex circuit, 7...
・Frame delay circuit, 8...Yl, 'separation circuit, 9.
... Subtraction circuit, 10... Synchronous detection circuit, 13... Decoder circuit.

Claims (1)

[Claims] The components of the image signal that exceed the signal band of the current television standard are converted into high-definition information by frequency shifting into reduced components and multiplexed.
In the “time-vertical” frequency domain, f=0 or ±
A television signal transmission system characterized in that the frequency shift is realized using a carrier wave μ_0 having a time frequency component other than 15 Hz.