JPH0666743B2 - Video multiplex transmission system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to synchronously transmitting a plurality of video signals,
The present invention relates to a video multiplex transmission system.

(Prior Art) Conventionally, in a method of simultaneously transmitting a plurality of video signals in one direction or two directions, (a), converting a plurality of video signals into different frequencies each having a higher frequency Simultaneous transmission using one transmission path by either multiplexing or (b) converting a video signal which is an analog signal into a digital signal and time-division multiplexing each of the digital signals. It was

FIG. 3 is a block configuration diagram of a video multiplex transmission apparatus for explaining the time division multiplex transmission method of (b) above, showing the case of eight channel multiplexing. 1 is a channel (hereinafter, ch
2) Indicates a video signal group consisting of 1 to ch8
Is an A / D converter group composed of A / D (analog / digital) converters A1 to A8, 3 is a time division multiplexer,
4 is a transmission line, 5 is a time division demultiplexer, 6 is a D / A converter D1
To D8, and D is a D / A converter group, and 7 is a video signal group composed of the restored eight ch1 to ch8 video signals.

FIG. 4 is a diagram for explaining the operation of FIG. 3, showing a video signal after being converted into a digital signal. The digital video signals of ch1 to ch8 in FIG. 3 are from ch1 as shown in FIG. ch8
Arranged in columns up to time, but each of its video signals
ch is A /, as shown in FIG.
The D converter A2 quantizes the data into, for example, 8 bits, and the time-division multiplexer 3 adds the frame signal bit F2 to form a temporally serial bit array. The time series of digital signals in which each channel is configured in this way from ch1 to ch8 is sent to the transmission line 4,
It is input to the time division separation device 5. This time division separation device 5
Then, the input ch1 to ch8 is separated from the digital signal array as shown in FIG. 4 (a) for each bit string corresponding to each channel as shown in FIG. 4 (b), and the D / A is set for each bit string. Frame signal bits applied to converters D1 to D8
F1 to F8 (however, the subscripts correspond to the subscripts of the D / A converters D1 to D8) are removed and reproduced as analog video signals ch1 to ch8.

In the conventional video multiplex transmission method, particularly the time division multiplex method, a plurality of video signals are digitally converted as described above and are simultaneously transmitted through one transmission line.

(Problems to be Solved by the Invention) However, in the digital time division multiplex transmission method as described above, an A / D for digitizing and transmitting a video signal is transmitted.
A D converter or a D / A converter is required, and the bit rate when a video signal is quantized into, for example, 8 bits is about 90 Mb / s. At this rate, n channels (n is arbitrary) A positive integer), for example, 8ch time-division multiplexing requires an extremely high transmission rate of 8 × 90 Mb / s, which is a major drawback in that the signal rate is difficult in terms of circuit technology.

The present invention has been made in view of the above, without increasing the transmission rate,
The present invention provides a video multiplex transmission method for multiplex transmission of a plurality of video signals, which is relatively easy to configure.

(Means for Solving the Problems) In order to achieve the above object, the present invention establishes vertical synchronization between a plurality of video signals to be transmitted, and a video signal of one vertical synchronization period of each video signal is converted into one vertical signal. It is characterized in that a time slot is sequentially provided for each synchronization period, and analog signals are multiplexed and transmitted so that video signals do not overlap each other.

That is, the present invention, in multiplex transmission of a plurality of video signals by analog signals, vertically synchronizes the plurality of video signals with each other, and delays the video signal of one vertical synchronization period of each video signal by one vertical synchronization period. The video signals of one of the plurality of video signals in one vertical synchronization period are formed into a signal sequence in which the video signals are cascaded to be transmitted, and the video signal is transmitted from the transmitted signal sequence on the receiving side. Are delayed by one vertical synchronization period and extracted as a plurality of signal trains to form a plurality of signal trains in which only video signals of the same video signal are arranged,
The above-mentioned conventional drawbacks are eliminated by interpolating the blanks between the video signals of the respective signal trains by using the video signals of the same video signal when the signal trains are formed.

(Operation) Since the present invention has a multiplex structure of analog signals as described above, A / D and D / A converters are not required as in the conventional case, and in the conventional case, if there are many video signals to be multiplexed. The higher the number, the higher the required transmission speed, and the advantage is that the analog signal form can be transmitted at the same speed as before the multiplexing.

(Examples) Hereinafter, the present invention will be described in detail by examples with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
The video signal to be multiplexed is shown as 8 channels.
8 is a video signal ch of the analog signal format to be multiplexed
Video signal group consisting of 1 to ch8, 9 is video signal group 8
And a synchronizing circuit for synchronizing the vertical synchronizing signal of each of the ch1 to ch8 video signals constituting one of them with one of the vertical synchronizing signals, and a switch circuit S1 for extracting a video signal of one vertical synchronizing period of the video signal. A control circuit for generating a signal for operating the switch circuits S1 to S8 in order to extract the video signals for each vertical synchronization period of the video ch1 to ch8 in synchronization with the vertical synchronization signal. A circuit, 11 is its output, 12 is an adder circuit for adding the output signals of the switch circuits S1 to S8, and 13
Is a transmission line. In addition, 14 is a video signal (that is, one frame of video) from the output of the adder circuit 12 applied via the transmission line 13 for each vertical synchronization period corresponding to the video signal ch in order from each video signal. A separation control circuit that generates a pulse for extracting, 15 is the output pulse,
Reference numeral 16 is a switch circuit for separating a video signal of one vertical synchronization period from each video signal of the video signals ch1 to ch8 in the output of the adder circuit 12 applied via the transmission line 13, and 7 is other than itself. Vertical sync period correction circuit group S'1 or S'8 for interpolating the vertical sync period from which the other video signals are extracted with the video signal of its own vertical sync period, 18 Is a pulse signal which is the output of the separation control circuit 14 for its control, and 19 is a video signal output group which is multiplexed and reproduced.

FIG. 2 is a supplementary diagram of FIG. 1 and shows a method of temporally multiplexing video signals. FIG. 2 (a) shows one frame of video for each vertical synchronization period showing ch1 and chb2 of the video signal as an example. Signals # 1 to #n (n is an arbitrary positive integer and can generally take an infinite value, but in this embodiment, n =
8), and (b) shows the video signals ch1 to ch8 from the vertical synchronizing period array as shown in the example in (a) above in order of the video signals in the vertical synchronizing period of each channel in a time division manner. An example of the multiplexed signal arranged in FIG. (C) is a switch circuit
16 is a signal diagram showing the video signal ch1 as an example.
For example, frame # 1 for ch1 and frame # 2 for ch2
The vertical synchronization period (however, the frame number is calculated from the same point in time) is extracted, and there is a temporal gap between them, and (d) shows the above-mentioned temporal gap of its own vertical synchronization period. The pattern interpolated with the video signal is shown.

In the device shown in FIG. 1, first, when eight video signals ch1 to ch8 are input, for example, a vertical sync signal included in a video signal of ch1 and a vertical sync signal of another video signal of ch2 to ch8 are input. The control circuit 10 receives the vertical synchronizing signal synchronized by the switch circuits S1 to S8, generates pulses 11 sequentially shifted by one vertical synchronizing period, and the switch circuits S1 to S8 receiving the pulse 11 cause the video signals ch1 to S8. c
Video signals for one vertical synchronization period are sequentially extracted from h8, and the extracted video signal for each vertical synchronization period is an adder circuit.
The signals are added at 12 and formed into one multiplexed video signal.

The switch circuit 16 receiving the multiplexed video signal extracts only its own ch portion from each ch under the control of the separation control circuit 14 and leaves the other ch portions blank as shown in FIG. 2 (c). The video signal array is used, and then each switch of the switch circuit group 17 is used to switch to another channel as shown in FIG. 2 (d).
The blank in which the video portion of is removed is interpolated using the video signal of the vertical synchronization period of its own.

That is, according to the present invention, the video signals are sequentially extracted from the plurality of video signals to be transmitted as described above by one vertical synchronization period for each channel, and the video signals are extracted one vertical synchronization period. It is characterized in that it is sent out via a transmission line, and the restoration of the signal to each channel is performed by a method almost the reverse of the case of transmission. In addition, the above-mentioned embodiment is 8
Although one video signal is shown as an example, it is obvious that it can be generally implemented by any number of video signals.

(Effects of the Invention) As is apparent from the above description, the present invention sequentially arranges video signals in each vertical synchronization period of a plurality of video signals and performs time division multiplexing. Since it can be converted, unlike the conventional multiplexing for digital conversion,
A / D and D / A converters are not required, and because it is not digitalized time division multiplexing, multiplex transmission in the same form as the original video signal without increasing the signal transmission rate after multiplexing There are advantages that can be made, and there are great benefits to using it.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention,
FIG. 2 is a signal arrangement diagram for explaining its operation, and FIG. 3 is a block diagram for explaining a conventional multiplexer.
The figure is a supplementary diagram for explaining the operation and shows the multiple signal arrangement. 1,8 …… Video signal group, 2 …… A / D converter group, 3 ……
Time division multiplexer, 5 ... Time division separator, 6 ... D / A
Converter, 7,19 ... (reproduced) video signal group, 9 ...
Switch circuit group, 10 ... Control circuit, 12 ... Addition circuit, 14
...... Separation control circuit, 16 …… Switch circuit, 17 …… Vertical synchronization period correction circuit group.

Claims (1)

[Claims] 1. In multiplex transmission of a plurality of video signals by analog signals, the plurality of video signals are vertically synchronized with each other, and the video signal of one vertical synchronization period of each video signal is delayed by one vertical synchronization period. The video signals of one of the plurality of video signals in one vertical synchronization period are formed into a signal sequence in which the video signals are cascaded to be transmitted, and the video signal is transmitted from the transmitted signal sequence on the receiving side. Are delayed by one vertical synchronization period and extracted as a plurality of signal trains to form a plurality of signal trains in which only the video signals of the same video signal are arranged, and the blanks between the video signals of the respective signal trains are A video multiplex transmission method characterized in that when a signal sequence is formed, interpolation is performed using video signals of the same video signal.