JPS62261291A - Time base multiplex device - Google Patents

Abstract

PURPOSE:To suppress a waveform distortion such as ringing to occur in the vicinity of the connecting part of a signal by providing a transition level generating means so that the division between different levels in the melting point of respective signals, for which the time base multiplexing is executed, can be changed at the level transition along the curve set beforehand. CONSTITUTION:A ROM 6 stores beforehand the waveform of a curve to link a blanking level between chrominance signal and a luminance signal, namely, the waveform of a transient signal. After chrominance signal data of one scanning line are read, a switch 11 is changed over to a contact 112, the data read from the ROM 6 are D/A-converted and the waveform of the curve to link the blanking level of the luminance signal read next to the chrominance signal and said chrominance signal is outputted. At such a time, even when the waveform to connect the division between the chrominance signal and the luminance signal and a synchronizing signal and the chrominance signal is band-limited, the waveform is formed by the data written in the ROM 6 beforehand so that the waveform distortion such as ringing cannot occur in the vicinity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a time domain multiplexing device necessary for time domain multiplexing and transmission of signals.

[Conventional technology]

When attempting to transmit information generated from a plurality of signal generation sources through fewer transmission paths than the number of signal generation sources, the plurality of signals must be multiplexed in a form that can be separated on the receiving side.

As an example of this, there is a case where it is attempted to transmit the luminance signal Y, wideband color signal CW, and narrowband color signal Cn in a color television signal through one transmission path.

In this case, each scanning line on the television screen has the three video signals mentioned above, but in order to transmit these through one transmission path, the wideband color signal Cw is transmitted for each scanning line. and the narrowband color signal Cn are alternately selected, and the result shown in FIG.
The time axis is compressed as shown in al. On the other hand, for the luminance signal Y, all scanning lines are time-axis compressed as shown in FIG. It is transmitted through a single transmission path as a waveform as shown in Figure 3 (C). At this time, in the above signal, since the level during the blanking period at both ends of one scanning line is different for the chrominance signal and the luminance signal, conventionally the level during this period is changed linearly as shown in Fig. 4. The settings had been made.

[Problem that the invention seeks to solve]

As described above, when multiplexing a plurality of signals on the time axis, if the levels at the end points of each signal differ depending on the signal, conventionally the level between them is changed linearly.

However, in such a method, if the level transition period is shortened to increase multiplexing efficiency, high frequency components will occur in this part, and therefore, if the band is limited when passing through the transmission system, ringing etc. will occur near the level transition part. There was a problem in that waveform distortion occurred, which adversely affected the video signal.

This invention was made to solve the above-mentioned problems, and even if the band is limited during the transmission process, waveform distortion such as ringing does not occur near the connection part of each time-axis multiplexed signal. The object is to obtain a time domain multiplexing surface that can obtain time domain multiplexed signals.

[Means for solving problems]

The time domain multiplexing device according to the present invention is provided with transition level generating means so that the levels at the end points of each time domain multiplexed signal change with level transitions along a preset curve.

[Effect]

In the present invention, even if the high frequency component is attenuated due to band limitation during the transmission process, a time-domain multiplexed signal is output in which waveform distortion such as ringing is less likely to occur near the connection portion of each time-domain multiplexed signal.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a time domain multiplexing device according to an embodiment of the present invention. In the figure, 12 is an input terminal for a luminance signal Y;
3.14 are wideband color signal CW and narrowband color signal C, respectively.
The input terminal 15 is an input terminal for a synchronization signal (SYNC). 1, 2.3 are input terminals 12.13.1 respectively
An A/D converter converts the signal from 4 into a digital signal, and 9 is a switch that switches the output of the A/D converter 2.3 for each scanning line. 4.5 are each A/D converter 1
゜Digital memory (hereinafter referred to as RAM) into which digital data from switch 9 is written; 6 is a waveform of a curve connecting the blanking level between the color signal and the luminance signal;
That is, it is a read-only memory (transition level generating means; hereinafter referred to as ROM) that stores the waveform of a transition signal in advance.

Further, 10 is a changeover switch that switches and outputs the output of RAM4.5, and 1) is the changeover switch 10 and R
A changeover switch (signal insertion means) switches between the output of OM6 and the output, and 8 is a clock that creates a clock and control signal using the input synchronization signal.

In the control signal generation circuit, 7 is a D/A converter.

Next, the operation will be explained.

A luminance signal Y is inputted from an input terminal 12, and a wideband color signal Cw and a narrowband color signal Cn are inputted from input terminals 13 and 14, respectively, and these input signals are converted into digital signals by A/D converters 1 and 2.3. converted. Among these, digital data corresponding to the luminance signal is written to the RAM 4, and digital data corresponding to the color signal is written in Cw for each scanning line.
Cn is alternately selected by the changeover switch 9, and the RAM 5
will be written to. At this time, a synchronization signal is input from the input terminal 15, and the clock and control signal generation circuit 8 uses the synchronization signal to generate clock and control signals for controlling each memory and each switch. .

The video signal data written in the RAM 4 and RAM 5 undergoes time axis compression by being read out at shorter time intervals than when they are written. At this time, color signal data for one scanning line is first read out. The switches 10.1) are respectively switched to the contact 102° and the contact 1.1), and the read color signal data is converted into an analog signal by the D/A converter 7, and is converted into a time-axis compressed color signal. Output. After one scanning line worth of color signal data is read out, switch 1) is switched to contact 1) 2, and RO
The data read out from M6 is D/A converted, and a curved waveform connecting the color signal and the blanking level of the luminance signal read out next to the color signal is output. Thereafter, the switch 10 is switched to the contact 101, and the switch 1) is switched to the contact 1)1, and the luminance signal data for one scanning line is D/A converted and output. After one scanning line worth of luminance signal data has been read out, switch 1) returns to contact 1) 2.
The synchronizing signal and the data corresponding to the curve connecting the synchronizing signal and the blanking level of the color signal are read from the ROM 6, D/A converted, and output. Thereafter, the above process is repeated, and the time-base compressed signal shown in FIG. 2 is output, forming a signal sequence as shown in FIG. 3.

At this time, the waveforms connecting the chrominance signal and the luminance signal and the synchronization signal and the chrominance signal are formed by data written in advance in the ROM 6 so that waveform distortion such as ringing will not occur in the vicinity even if the band is limited. be done. This connection waveform uses a shape that has been confirmed in advance by computer simulation or the like to cause less waveform distortion such as ringing even if the band is limited during the transmission process. An example of this shape is a so-called window function that is often used in digital signal processing, such as a Kaiser window, a Hanning window, a Hamming window, and a Blackman window.

In the above embodiment, one scanning line period is formed in the order of the synchronization signal, the eight color signals, and the luminance signal, but this order may be reversed.

Furthermore, although the above embodiment deals with video signals, the present invention is effective not only in the case of time-axis multiplexing of many types of signals having different levels at their end and start ends.

Further, in the above embodiment, an example in which the time axis is compressed has been described, but the same applies to cases where the time axis is not compressed or the time axis is expanded, as long as the time axis is multiplexed.

Furthermore, in the above embodiment, the input signal is A/D converted
Although a RAM is used, it is also possible to store the analog signal as it is in an analog storage means and time-base multiplex the data read from the ROM using an analog waveform obtained by D/A conversion.

〔Effect of the invention〕

As described above, according to the present invention, when signals are multiplexed on the time axis, if there is a level difference between the end points of each signal, the difference between them is configured to change along a preset curve. Even if the band is limited in the process, it has the effect of suppressing waveform distortion such as ringing that occurs near the signal junctions.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a time-axis multiplexing device for video signals according to an embodiment of the present invention, FIG. 2 is a diagram showing signals formed by the device, and FIG. Fig. 4 is a diagram showing the process of time axis compression multiplexing of signals, and a diagram showing conventional time axis multiplexing waveforms. 1.2.3...A/D converter, 4, 5...RAM. 6...ROM, 7...D/A converter, 8...clock. Control signal generation circuit, 9.10.1)...changeover switch.

Claims (2)

[Claims] (1) In a time-domain multiplexing device that transmits many types of signals in a time-division manner via the same transmission path, the terminal level of the preceding signal on the time-domain among the time-division multiplexed signals and the level of the next signal Transition level generating means for generating a transition signal for changing the level along a predetermined curve between signals having different levels from the starting end of the signals, and signal inserting means for inserting the transition signal between the two signals. A time axis multiplexing device characterized by: (2) The signal waveform curve of the transition signal has the shape of any one of a Hanning window, a Hamming window, a Blackman window, and a Kaiser window used in digital signal processing. time axis multiplexer.