JP2618859B2 - Time axis multiplexing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time axis multiplexing device required for transmitting a signal in a time axis multiplex.

[Conventional technology]

If information generated from a plurality of signal sources is to be transmitted on a transmission path having fewer channels than the number of signal sources, a plurality of signals must be multiplexed in a form that can be separated on the receiving side.

As an example of such a case, there is a case in which a luminance signal Y, a wideband color signal Cw, and a narrowband color signal Cn in a color television signal are to be transmitted through one transmission line. In this case, the above three video signals are present on each scanning line on the television screen. In order to transmit the three video signals through one transmission line, the color signals are broadband color signals for each scanning line.
Cw and the narrow-band color signal Cn are alternately selected, and FIG.
The time axis is compressed as shown in FIG. On the other hand, the luminance signal Y is time-axis-compressed for all the scanning lines as shown in FIG. 3 (b), and at the same time, the time-axis-compressed color signal and the horizontal synchronizing signal are added, and the time-axis-compressed third signal is multiplexed. The waveform as shown in FIG. 3C is transmitted through one transmission line. At this time, in the above signal, since the level in the blanking period at both ends of one scanning line is different between the chrominance signal and the luminance signal, conventionally, the level during this period changes linearly as shown in FIG. The settings have been made.

[Problems to be solved by the invention]

As described above, when a plurality of signals are time-division-multiplexed, if the level at the end point of each signal differs depending on the signal, the interval between the signals is conventionally changed linearly. However, in such a method, if the level transition period is shortened in order to increase the multiplexing efficiency, high frequency components are generated in this portion. Therefore, when the band is limited when passing through the transmission system, ringing or the like occurs near the level transition portion. Waveform distortion occurs, which adversely affects the video signal.

The present invention has been made to solve the above problems, and even if the band is limited during the transmission process,
It is an object of the present invention to provide a time axis multiplexing device capable of obtaining a time axis multiplexed signal in which waveform distortion such as ringing does not occur near a connection portion of each time axis multiplexed signal.

[Means for solving the problem]

In the time axis multiplexing apparatus according to the present invention for transmitting signals generated by a plurality of signal generation sources in a time-division manner through the same transmission path, the time-division multiplexed signal includes a signal that precedes on the time axis. A transition signal connecting a signal having a known level at the end of the signal and a signal having a known level at the beginning of the succeeding signal different from each other is formed along a shape of a Hanning window, a Hamming window, a Blackman window, or a Kaiser window. A transition level storing means for storing a signal to be input, a signal selecting means for receiving the transition signal and the time-division multiplexed signal, and selecting and outputting one of the input signals; A control signal for generating a control signal for causing the transition level storage means to output the transition signal, and causing the signal selection means to output the transition signal. It is obtained by so and a raw device.

[Action]

In the present invention, since the configuration is as described above, even if the band of the time-division multiplexed signal is limited and the high-frequency component is attenuated in the transmission process, the known level at the end of the preceding signal on the time axis is determined in advance. And the known level at the beginning of the following signal are different from each other, and the period between the end and the beginning is connected by a transition signal whose level transitions along a curve set in advance so as to reduce the occurrence of waveform distortion. .

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a time axis multiplexing apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 12 denotes an input terminal of a luminance signal Y, and reference numerals 13 and 14 denote input terminals of a wideband color signal Cw and a narrowband color signal Cn, respectively. , 1
Reference numeral 5 denotes a synchronization signal (SYNC) input terminal. 1, 2, and 3 are A / D converters for converting signals from the input terminals 12, 13, and 14 into digital signals, respectively, and 9 is a switch for switching the output of the A / D converters 2 and 3 for each scanning line. is there. 4 and 5 are A / D converters respectively
1, a digital memory (hereinafter referred to as RAM) to which digital data is written from the switch 9; It is a dedicated memory (transition level storage means; hereinafter, referred to as ROM). Reference numeral 10 denotes a changeover switch for switching and outputting the outputs of the RAMs 4 and 5, reference numeral 11 denotes a changeover switch (signal selection means) for switching and outputting the changeover switch 10 and the output of the ROM 6.
Reference numeral 8 denotes a clock and a control signal generation circuit (control signal generation means) for generating a clock and a control signal using the input synchronization signal, and reference numeral 7 denotes a D / A converter.

 Next, the operation will be described.

A luminance signal Y is input from an input terminal 12, and a wideband color signal Cw and a narrowband color signal Cn are input from input terminals 13 and 14, respectively, and these input signals are converted into digital signals by A / D converters 1, 2, and 3. Is converted. Among them, digital data corresponding to the luminance signal is written to the RAM 4, and digital data corresponding to the chrominance signal is alternately selected by the switch 9 for each scanning line by the switch 9 and written to the RAM 5. At this time, a synchronizing signal is input from the input terminal 15, whereby a clock and a control signal for controlling each memory and each switch are created in the clock and control signal generating circuit 8 using the synchronizing signal. .

The video signal data written to RAM4 and RAM5 is
The data is read out at shorter time intervals than at the time of writing, so that it undergoes time axis compression. At this time, first, color signal data for one scanning line is read. Switches 10 and 11 each have contact 1
02, the contact point is switched to 111, and the read color signal data is converted into an analog signal by the D / A converter 7 and output as a time-axis-compressed color signal. After the color signal data for one scanning line is read, the switch 11 is switched to the contact point 112, and the data read from the ROM 6 is D.
The waveform of the curve connecting the color signal and the blanking level of the luminance signal to be read next to the color signal is output. Thereafter, the switch 10 is switched to the contact point 101 and the switch 11 is switched to the contact point 111, and the luminance signal data for one scanning line is D / A converted and output. After the luminance signal data for one scanning line has been read, the switch 11
2, the data corresponding to the synchronization signal and the curve connecting the synchronization signal and the blanking level of the color signal are read out from the ROM 6, and D / A converted and output. Thereafter, the above process is repeated, and a signal whose time axis is compressed as shown in FIG. 2 is output, and a signal sequence as shown in FIG. 3 is formed.

At this time, the waveform connecting the chrominance signal and the luminance signal and the waveform connecting the synchronizing signal and the chrominance signal are stored in the ROM 6 in advance so that waveform distortion such as ringing does not occur in the vicinity even if the band is limited.
Is formed by the data written in. As the connection waveform, a shape is used in which it is confirmed that the occurrence of waveform distortion such as ringing is small even if the band is limited in the course of transmission by computer simulation or the like. As an example of this shape, there is a so-called window function often used in digital signal processing, and a Kaiser window, a Hanning window, a Hamming window, a Blackman window, or the like is used.

In the above embodiment, one scanning line period is formed in the order of the synchronizing signal, the chrominance signal, and the luminance signal. However, this order may be interchanged.

Further, in the above embodiment, the video signal is targeted. However, the present invention is not limited to the video signal, and the present invention is also effective in the case of time-division multiplexing of various types of signals having different levels at the end and the start.

In the above embodiment, the example in which the time axis is compressed has been described. However, the case where the time axis is not compressed or the time axis is expanded can be similarly applied as long as the time axis is multiplexed.

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

〔The invention's effect〕

As described above, according to the time multiplexing apparatus of the present invention, in the time axis multiplexing apparatus that transmits signals generated by a plurality of signal sources in a time-division manner through the same transmission path, the time-division multiplexing is performed. As a transition signal connecting signals having different known levels at the end of the preceding signal on the time axis and the known level at the beginning of the next signal, the signal is a Hanning window, a Hamming window, or a Blackman window. ,
A transition level storage unit that stores a signal that transits along any shape of the Kaiser window; and the transition signal and the time-division multiplexed signal are input, and any one of the input signals is selected. A signal selecting means for outputting, and a control signal for causing the transition level storing means to output the transition signal and for causing the signal selecting means to output the transition signal in a period between the end and the starting end. Since the control signal generating means is provided, even if the band is limited in the course of transmission, there is an effect that waveform distortion such as ringing generated near a joint portion of a signal can be suppressed.

[Brief description of the 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 FIGS. 3 (a), (b) and (c) are FIG. 4 is a diagram showing a process of time axis compression multiplexing of a video signal, and FIG. 4 is a diagram showing a conventional time axis multiplexed waveform. 1,2,3 ... A / D converter, 4,5 ... RAM, 6 ... ROM, 7 ... D
/ A converter, 8 ... clock, control signal generation circuit, 9, 10, 1
1… Changeover switch.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location H04N 11/24 (56) References JP-A-48-89624 (JP, A) JP-A-60- 89173 (JP, A) JP-A-60-263572 (JP, A) JP-A-60-170747 (JP, A) Transactions of the Institute of Electronics, Communication and Communication Engineers J68-D [4] (1985.4) 647-654

Claims (2)

(57) [Claims] A time-division multiplexing device for transmitting signals generated by a plurality of signal generation sources in a time-division manner through the same transmission path; As a transition signal that connects signals having different known levels at the end of the signal and the known level at the beginning of the following signal, the transition signal follows any one of the shapes of the Hanning window, the Hamming window, the Blackman window, and the Kaiser window. Transition level storage means for storing a signal to be transitioned, signal selection means for receiving the transition signal and the time-division multiplexed signal as input, selecting one of the input signals and outputting the selected signal, A control signal for generating a control signal for causing the transition level storage means to output the transition signal and causing the signal selection means to output the transition signal during a period between the start and end points. Time axis multiplexer being characterized in that a raw device. 2. The time axis multiplexing device according to claim 1, wherein the signals generated by the plurality of signal sources include a luminance signal, a wideband chrominance signal, and a color television signal.
A time axis multiplexing device characterized by being a narrow band color signal.