JP2965162B2 - High-definition television signal transmission system and reception system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal transmission method, and more particularly to a transmission method suitable for equalizing a high-definition television signal transmission path in which multiple sub-sample band compression transmission is performed. It relates to a system and a receiving system.

(Summary of the Invention) The present invention relates to a transmission system of a MUSE signal (high-definition television signal), and a VIT signal (Vertical Interal Test Sig) conventionally inserted for automatic transmission path equalization.
nal) is periodically greater than the normal signal level.

By doing so, equalization of high-frequency large-amplitude characteristics, in which the MUSE signal is not sufficiently equalized due to FM and high-frequency emphasis transmission, can be realized, and a transmission method compatible with conventional transmission path equalization can be obtained. Can be

(Prior Art) A high-definition television signal which performs motion-compensated multi-subsample band compression transmission, especially MUSE (Multiple Sub-sample)
In a -Nyquist Smapling Encoding signal, the amplitude of a VIT signal (Vertical Interval Test Signal) pulse is almost the same as the video amplitude level in the state of a source signal conventionally generated at a clock rate of 32.4 MHz. The reason for this is that the purpose of equalization with the VIT signal is the linear distortion of the transmission system.If the amplitude of the VIT signal is too large, there is a concern that the effect of nonlinear distortion will increase and accurate equalization of the transmission path cannot be achieved. It is because. For a detailed description of the MUSE signal described above, see the literature, Ninomiya et al .: Development of MUSE System, NHK
See Technical Research, Vol. 39, No. 2, pp. 18-53, 1987.

(Problems to be Solved by the Invention) Now, in the VIT signal of the normal amplitude level which has been set conventionally, FM transmission is performed like a MUSE signal, and a signal to be transmitted after being pre-emphasized to reduce noise based on FM transmission is transmitted. In some cases, the maximum video amplitude greatly exceeds the amplitude of the VIT signal. Therefore, in practice, it has been considered that it is more preferable to use a VIT signal having a larger amplitude level than in the past. However, on the other hand, there is a possibility that the predistorted nonlinear distortion may be forcibly equalized.
It would be good to match the use of VIT signals.

Therefore, an object of the present invention is to equalize the transmission path even when a high-definition television signal, for example, a MUSE signal, which is transmitted as a sample value for band compression, is further subjected to FM modulation and pre-emphasis, and transmitted. It is another object of the present invention to provide a high-definition television signal transmission system and a reception system thereof that can be suitably adopted.

(Means for Solving the Problems) In order to achieve this object, the high-definition television signal transmission system according to the present invention further comprises: In transmitting by pre-emphasis, the amplitude of a VIT signal pulse for transmission path equalization is periodically made larger than a normal signal level having almost the same amplitude level as a video amplitude level. .

Further, the high-definition television signal receiving system of the present invention is the high-definition television signal transmission system, and
The vertical flyback period in which the amplitude of the VIT signal pulse is large is controlled by an iteration flag of logic 1, and the amplitude of the VIT signal pulse in which the amplitude is large is determined in advance by a predetermined ratio with respect to the normal signal level. The high-definition television signal transmitted by the transmission method, upon receiving and equalizing on the receiving side based on the transmitted VIT signal, for the VIT signal for each frame extracted on the receiving side, At the corresponding time, it is determined whether the signal level is the normal signal level by the logic of the iteration flag in the control signal extracted at the corresponding time, and the VIT signal determined as the higher level and the VIT signal determined as the normal level are compared. Performs nonlinear compensation based on the amplitude ratio, equalizes the amplitude of the received television signal, and increases the VI level
The frequency characteristic of the received television signal is compensated according to the transmitted frequency characteristic of the T signal, the transmitted frequency characteristic of the normal level VIT signal, and the characteristic of the nonlinear compensation.

(Embodiment) High-definition television signal of band compression transmission type such as MUSE
The signal contains a series of control signals, which can be used to distinguish between static or static images, for moving pictures, for example, the degree of movement, or for emphasis whether the transmission is AM or FM. And information on whether or not they are running.
The above-mentioned VIT signal includes a control signal called an iteration flag.

When the iteration flag signal performs the equalizing operation on the encoder side (transmitting side), the decoder side (receiving side) also performs the equalizing operation at the same time, thereby preventing the encoder side and the decoder side from conflicting with each other. It is inserted for the purpose. Therefore, in the conventional ordinary decoder, the equalization operation is not performed when the iteration flag signal is at logic 1, and there is no problem whatever is transmitted as the VIT signal during this period. On the other hand, the equalizing operation on the encoder side is performed on the assumption that the receiving side assumes a "reference receiver" having relatively good characteristics and S / N. Therefore, it is sufficient to perform the equalizing operation with the conventional small-amplitude VIT signal.

In order to determine a large-amplitude VIT signal from the above considerations, the iteration flag may be set to logic 1 at that time.

In the decoder corresponding to the transmission system according to the present invention, the iteration flag is logic 1 and the VIT
When the amplitude of the signal is large, it can be determined that the large-amplitude VIT signal is being transmitted. The magnitude of the amplitude of the VIT signal can be determined by comparing the amplitude of the VIT signal with that of the normal amplitude signal, since there is always a period during which the signal is transmitted. In addition, large amplitude
If the amplitude ratio of the normal amplitude of the VIT signal to the VIT signal is set to a predetermined value in advance, the nonlinear distortion of this transmission system can be estimated from the detected amplitude, so it can be applied to the equalization of nonlinear distortion. it can.

FIG. 1 is a block diagram showing a configuration example on the decoder side according to the transmission system of the present invention. In this example, the non-linear compensation circuit 6 employs an open-loop type equalization method which is provided after the VIT signal extraction circuit 2. However, as another embodiment, the non-linear compensation circuit 6 is used.
However, there is also a closed loop type equalization method which is provided before the VIT signal extraction circuit 2.

In the decoder configuration shown in FIG. 1, the received MUSE video signal is output as an equalized MUSE video signal via the A / D converter 1, the non-linear compensation circuit 6, and the f characteristic compensation circuit 10.

On the other hand, the VIT signal extracted by the VIT signal extraction circuit 2 on the encoder side is extracted from the received MUSE signal. According to this method, a VI with an amplitude level almost the same as the video amplitude level
Although a T signal (referred to as a small amplitude VIT signal) is also transmitted, a VIT signal having a larger amplitude than that which periodically replaces the small amplitude VIT signal is also transmitted. These large and small VIT signals, which are output signals of the VIT signal extraction circuit 2, are separately detected by the control signal detection circuit 3, and the magnitudes thereof are determined by the logic of the iteration flag. That is, when the logic is zero, the output from the magnitude discrimination circuit 4 is treated as a small amplitude VIT signal, and when the logic is 1, the output from the magnitude discrimination circuit 4 is the large amplitude VIT signal.
Treated as a T signal.

In this example, non-linear compensation is performed independently of f-frequency (frequency characteristic) compensation, and then amplitude and phase f-frequency compensation is performed using a transversal filter or the like.

In the nonlinear compensation, for example, five amplitude values are extracted based on two VIT signals of a large amplitude and a small (normal) amplitude, and the interval between them is reduced to the extent that secondary interpolation is performed. This example is shown in FIG.

As for the f-compensation, both the small amplitude characteristic and the large amplitude characteristic can be obtained independently of each other.
For example, a non-linear coefficient estimated according to the amplitude value by the method shown in FIG. 2 can be used.

As for f characteristic compensation, when the non-linear amplitude compensation is performed first as in this example, the linear addition of the large amplitude characteristic and the small amplitude characteristic is performed, and the linear coefficient obtained at an appropriate proportional ratio is used. However, it is more effective than using only the coefficient obtained from the small amplitude characteristic.

(Effects of the Invention) As described above in detail, according to the method of the present invention, when a high-definition television signal, for example, a MUSE signal, which is conventionally transmitted as a sample value for band compression, is further transmitted by FM emphasis, it is sufficient. The equalization of the large amplitude characteristic that has not been equalized can be performed in addition to the equalization of the conventional small amplitude characteristic.

[Brief description of the drawings]

FIG. 1 shows a block diagram of a configuration example on the decoder side according to the transmission system of the present invention, and FIG. 2 shows an example of estimating nonlinear compensation characteristics. 1 A / D converter 2 VIT signal extraction circuit 3 Control signal detection circuit 4 Size discrimination circuit 5 Nonlinear detection circuit 6 Nonlinear compensation circuit 7 Small amplitude transmission characteristic measurement Circuit 8: Large amplitude transmission characteristic measurement circuit 9: Correction coefficient generator, 10: f-special compensation circuit

Claims (4)

(57) [Claims] 1. A high-definition television signal transmitted after being compressed in a motion-compensated multiplex sub-sample band, is further subjected to FM modulation,
A high-definition television, characterized in that the amplitude of a VIT signal pulse for transmission path equalization is periodically made larger than a normal signal level having almost the same amplitude level as a video amplitude level when transmitting with pre-emphasis. John signal transmission system. 2. The transmission system according to claim 1, wherein
During the vertical retrace interval when the amplitude of the T signal pulse is large,
A high-definition television signal transmission system, wherein an iteration flag in a control signal for controlling prohibition of an equalization operation on the receiving side is set to logic 1. 3. The high quality transmission system according to claim 1, wherein the amplitude of the VIT signal pulse when the signal level is larger than the normal signal level is set at a predetermined ratio as compared with the normal signal level. Television signal transmission system. 4. A high-definition television signal, which is transmitted after being compressed in a motion-compensated multiplex sub-sample band, is further subjected to FM modulation,
When transmitting with pre-emphasis, the amplitude of the VIT signal pulse for transmission line equalization is periodically increased by a predetermined ratio as compared with a normal signal having the same amplitude level as the video amplitude level, and the VIT The high-definition television signal transmitted with the iteration flag in the control signal for controlling the inhibition of the equalization operation being set to logic 1 on the receiving side during the vertical blanking period in which the amplitude of the signal pulse is large is transmitted. Upon receiving and equalizing on the receiving side based on the VIT signal thus obtained, the VIT signal for each frame extracted on the receiving side is determined by the logic of the iteration flag in the control signal extracted at a corresponding time. It is determined whether or not the signal level is a normal signal level, and nonlinear compensation is performed based on the amplitude ratio between the VIT signal determined to be a higher level and the VIT signal determined to be a normal level. While performing the equalization of the amplitude of the received television signal, according to the transmitted frequency characteristic of the larger level VIT signal, the transmitted frequency characteristic of the normal level VIT signal, and the nonlinear compensation characteristic, A high-definition television signal receiving method characterized by performing frequency characteristic compensation.