JPH02166982A - Data multiplexing system - Google Patents

Abstract

PURPOSE:To increase addition information quantity to be multiplexed by superimposing a guard band just before the synchronizing signal of a television signal and multiplexing the additional information between the guard band and a video signal. CONSTITUTION:A guard band 12 is superimposed so as to be overlapped to the falling of a horizontal synchronizing signal and the level of the guard band is 100% of the video signal. Thus, since the inclination of falling is made almost three times in comparison with a case that the guard band is not superimposed, the jitter of the horizontal synchronizing signal due to the leak of data, which are multiplexed between the guard band 12 and video signal, to a surrounding part is reduced to almost 1/3. Thus, the additional information to be multiplexed can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data multiplexing method for multiplexing additional information onto television video radio waves.

[Summary of the Invention] The present invention is a data multiplexing method for multiplexing additional information on television video radio waves, in which a guard band is superimposed immediately before the synchronization signal of the television signal, and additional information is multiplexed between this guard band and the video signal. This increases the amount of additional information to be multiplexed.

[Prior Art] In current television broadcasting, it has been considered to use a horizontal blanking period to transmit additional information such as audio, and such methods are also being considered.

The system being considered is one in which additional information is multiplexed on the back porch 4 and front porch 5 of a composite video signal as shown in FIG. However, although the back pouch 4 is wide open, it is used as a clamp or the like in the receiver, and there is only a small portion that can be used effectively. Therefore, multiplexing data to the front porch 5 is important, and the present invention relates to a method of multiplexing data to the front porch 5.

When multiplexing digital data, the data is first passed through a filter so that it can be received accurately after being transmitted. When passed through a filter, the multiplexed data becomes as shown in FIG. 5, for example.

[Problems to be Solved by the Invention] However, as shown in FIG. 5, the data after passing through the filter leaks to the surroundings, and this leakage affects the horizontal synchronizing signal.

In other words, the fall of the synchronization signal has a finite value due to transmission characteristics, and if leakage to the surroundings due to multiplexed data is added to this fall, jitter occurs in the synchronization signal depending on whether the data is L or H, and this jitter causes There was a problem in that horizontal jitter occurred in the receiver.

One way to solve this problem is to make the data multiplexing period sufficiently separate from the horizontal synchronization signal period, but this method introduces the new problem of reducing the amount of data that can be multiplexed. Ta.

Further, as a method for preventing jitter, there is a method of reducing the amplitude of multiplexed data, but this method has new problems in that it becomes more susceptible to the influence of noise and the service range becomes narrower.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data multiplexing method that can solve the above-mentioned problems and increase the amount of multiplexed data.

[Means for Solving the Problems] In order to solve these problems, the present invention superimposes a guard band immediately before the synchronization signal of a television signal, and multiplexes additional information between this guard band and the video signal. It is characterized by

[Function] In the present invention, a guard band is superimposed immediately before the synchronization signal of a television signal, and additional information is multiplexed between the guard band and the video signal to increase the amount of data to be multiplexed.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of a composite video signal embodying the present invention.

This superimposes the guard band on the falling edge of the horizontal synchronization signal, and the guard punt level is set to 1 of the video signal.
This is 0096.

In this case, the slope of the falling edge will be approximately three times that of the case where no guard band is superimposed, so the jitter of the horizontal synchronization signal due to leakage of data multiplexed between the guard band 12 and the video signal to the surroundings will occur. is reduced to approx.

Here, if the frequency characteristic of the filter is sin x /x, the accumulation of multiplexed data around the periphery will be as shown in Figure 2, and the size of the second leak will be approximately the size of the seventh leak. It will be tripled.

In this way, the multiplexed data is separated from the horizontal synchronization signal by 2.
The jitter when separated by 5'r (T: data width) is equal to the jitter when the conventional guard band is not provided and the multiplexed data is separated by 7.5T from the horizontal synchronization signal. FIG. 3 shows the positions at which multiplexed data is added. Therefore, the data per scanning line is 5 bits compared to the conventional method.
The number of bits increases by 75 kbit per sec.

In this embodiment, the guard band level is set to 100% of the video signal, but it is not limited to this level, and the width of the guard band is twice or more the falling period of the horizontal synchronization signal, that is, , 0.5 μsec or more is sufficient.

Furthermore, in this embodiment, an example in which a guard band is provided immediately before the horizontal synchronization signal of current television broadcast waves has been explained, but the synchronization signal may also be a vertical synchronization signal, and in the case of high-definition, A three-value synchronization signal may also be used.

[Effects of the Invention] As explained above, according to the present invention, a guard band is superimposed immediately before the synchronization signal of a television signal, and additional information is multiplexed between this guard band and the video signal.
This has the effect of increasing the amount of additional information to be multiplexed.

5...Front porch, 12...Guard band.

Claims (1)

[Claims] 1) A data multiplexing method characterized by superimposing a guard band just before the synchronization signal of a television signal and multiplexing additional information between the guard band and the video signal.