JPS6282892A - Optical bidirectional transmission system - Google Patents

Abstract

PURPOSE:To simultaneously transmit an one-way video signal and a bidirectional data signal through only one optical fiber by mutually transmitting digital data by using the vertical erasing period of the video signal. CONSTITUTION:When data are to be transmitted from a master station to a slave station, down data are inserted into the first half of an one horizontal scanning period (1H) in a prescribed vertical fly-back line erasing period of a video signal by a data superposing means 101 to send the down data and the slave station separates the data by a data separating means 102 to receive the data. After a fixed guard time from the end of receiving data, the slave station sends up data to the master station through a data transmitting means 103 and the data are inserted into the latter half of the 1H. The master station receives the data by a data receiving means 104. In a period other than the vertical fly-back line erasing period, a normal video signal is transmitted from the master station to the slave station.

Description

[Detailed Description of the Invention] [Summary] On the transmitting side of a system that transmits video signals via optical fibers, digital data is sent superimposed on the vertical blanking period of the video signal, and on the receiving side, this superimposition is The digital data is separated from the received signal to receive a video signal and a data signal, and the receiving side transmits the digital data during the vertical blanking period of the video signal, and the transmitting side receives this digital data. So,
A unidirectionally transmitted video signal and a bidirectionally transmitted data signal can be simultaneously transmitted via a single optical fiber.

[Industrial application field]

The present invention relates to an optical bidirectional transmission system, and more particularly to an optical bidirectional transmission system that transmits a unidirectionally transmitted video signal and a bidirectionally transmitted data signal using a single optical fiber.

In the age of new media, there is an increasing demand for systems that can simultaneously transmit video, audio, data, etc. Such services are provided for subscribers, and economic efficiency is required in order to popularize them.

The optical bidirectional transmission system of the present invention is intended to provide a system that can meet such demands without performing wavelength multiplexing and by using a bidirectional transmission format.

[Conventional technology]

Problems to be Solved by the Invention] However, a teletext broadcasting system that transmits text information by using the vertical blanking period in a television signal is used to simultaneously transmit a video signal and a data signal. The teletext broadcasting system is used as a broadcasting format, that is, it only transmits information in one direction, and cannot transmit information in both directions.

The present invention is directed to making it possible to transmit a unidirectionally transmitted video signal and a bidirectionally transmitted data signal using a single optical fiber.

Means for Solving Problem C] Figure 1 shows the basic configuration of the system of the present invention. In a system that transmits a video signal via an optical fiber,
A data superimposing means (101) and a data receiving means (
104) and data separation means (102) on the receiving side.
and data transmission means (103).

The data superimposing means (101) superimposes digital data on the vertical blanking period of the video signal and transmits the superimposed data.

The data separation means (102) separates digital data from the above-mentioned superimposed signal.

The data transmitting means (103) transmits digital data during the vertical blanking period of the video signal.

The data receiving means (104) receives the digital data.

[For production]

In a system that transmits video signals via optical fiber, we have made it possible to mutually transmit digital data using the vertical blanking period of the video signal. The transmission data signal and the transmission data signal can be simultaneously transmitted through one optical fiber.

〔Example〕

FIG. 2 shows the configuration of an embodiment of the present invention, in which (a) shows a mask station, fb) shows a slave station, and both are connected by one optical fiber 1. In the mask station, 11 is a reference clock source, 12 is a clock generation circuit, 13 is a speed conversion circuit, 14 is a hybrid,
15 is a driver, 16 is an LED (light emitting diode)
element, 17 is a receiver, 18 is a timing extraction circuit, 1
9 is a frame synchronization circuit, and 20 is a frame synchronization circuit in the slave station.
is a speed conversion circuit, 21 is an LED (light emitting diode)
22 is a receiver, 23 is a synchronous separation circuit, 24 is a clock generation circuit, 25 and 26 are speed conversion circuits, and 27 is a driver.

In the mask station, a reference clock source 11 generates a reference clock that serves as a reference for all clocks.

The clock generation circuit 12 on the mask station side generates various clocks necessary for the operation of the mask station side using the reference clock from the reference clock source 110. The speed conversion circuit 13 writes data input Data In having the data speed of the terminal from a terminal (not shown) using the write clock W from the clock generation circuit 12, and converts the speed by reading this data using the read clock R and converts it into a video signal. It is inserted into the vertical blanking period of 1 and added to the hybrid 14. On the other hand, the video input Video In is directly applied to the hybrid 14. Both signals superimposed in the hybrid 14 are amplified via the driver 15 and sent to the LE.
The signal is applied to the D element 16, converted into an optical signal, and sent out to the slave station via the optical fiber 1.

The optical signal sent through the optical fiber 1 is applied to the LED element 21 at the slave station and converted into an electrical signal.
The video signal is amplified through the receiver 22 and directly output as video output Video Out.

On the other hand, the synchronization separation circuit % separates the synchronization signal from the receiver output, and the clock generation circuit 24 generates a clock synchronized with the input from the separated synchronization signal.

The speed conversion circuit 25 writes the data signal inserted in the vertical blanking period of the input video signal using the write clock W from the clock generation circuit 24, and further reads it using the read clock R from the clock generation circuit 24. The data is converted to the data rate of the terminal by , and sent to a terminal (not shown) as data output Data Out. The read clock R is the clock output C1ock Ou for the processing of data in the terminal.
It is sent to the terminal together with the data output as t.

On the other hand, the speed conversion circuit 26 converts data input from the terminal to the slave station, which has the data speed of the terminal.
In is written by the write clock W of the clock generation circuit 24 and read by the read clock R to convert the speed and send it out during the vertical blanking period of the video signal. This signal is amplified via the driver 27, applied to the LED element 21, converted into an optical signal, and sent via the optical fiber 1 to the mask station. In the speed conversion circuit 26, the read clock R in the speed conversion circuit 25 is used as the write clock W, and the write clock W in the speed conversion circuit section is used as the read clock R.

The LED X element 16 of the mask station converts the received optical signal into an electrical signal, and the converted signal is amplified via the receiver 17. The timing extraction circuit 18 extracts the timing component from the signal of the receiver 17, and the frame synchronization circuit 19 extracts the frame synchronization signal from the input signal.
Generates a clock W for writing input signals. The speed conversion circuit 2o converts the receiver 17 using this write clock.
The input signal from the clock generation circuit 12 is written and read out by the read clock R from the clock generation circuit 12 to convert it to the data rate of the terminal, and the data output Data O
It is sent to a terminal not shown as t. Note that in the speed conversion circuit 20, the read clock R is as follows:
A write clock W in the speed conversion circuit 13 is used. The read clock R is sent to the terminal together with the data output as a clock output C1ock Out for processing data in the terminal.

In the embodiment shown in FIG. 2, the LED elements 16 and 21 are used for both transmission and reception. This is because the LED element is used as a light emitting element due to its electrical/optical conversion function, and it also
This is because it has an electrical conversion function and is also used as a light receiving element. In this way, without using an element for transmitting and receiving,
It goes without saying that the light emitting element and the light receiving element may be used separately and coupled into one optical fiber.

FIG. 3 is a time chart illustrating the operation of the embodiment shown in FIG. 2, and shows only the vertical retrace period of the video signal. In the figure, (1) shows the transmission signal on the mask station side when transmitting from the mask station to the slave station, and (2)
) indicates the received signal on the slave station side.Also, (3) indicates the transmitted signal on the slave station side when transmitting from the slave station to the mask station, and (4) also indicates the received signal on the mask station side. In each of these figures, A indicates a television horizontal synchronization signal, and B indicates a color burst signal.

In the system of the present invention, when a television signal is used as a video signal as in the case of teletext broadcasting, any scanning line from the 10th horizontal scanning period to the 21st horizontal scanning period of the vertical blanking period is used. is used to transmit data. When transmitting from a mask station to a slave station, 1
The first half of the horizontal scanning period (IH) is used to send downlink data. Fig. 3 f1. l) The slave station receives the data thereby ((2) in FIG. 3). On the other hand, in the slave station, there is a fixed guard time T from the end of the received data.
After that, uplink data is sent to the master station, but this data is inserted in the latter half of one horizontal scanning period (see Figure 3).
3)), the mask station receives data by this (
Figure 3 (4)).

In this case, a normal video signal (television signal) is being transmitted from the mask station to the slave station except for the vertical blanking period, and therefore, according to the method of the present invention, the unidirectionally transmitted video signal Simultaneous transmission with the data signal transmitted in the opposite direction is performed.

〔Effect of the invention〕

As explained above, according to the system of the present invention, a single optical fiber is used to transmit a unidirectionally transmitted video signal and a bidirectionally transmitted data signal using a multiplexing means such as an optical wavelength division multiplexing method. It can be realized extremely economically.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of the present invention, FIG. 2 is a diagram showing the configuration of an embodiment of the method of the present invention, and FIG. 3 is a time chart explaining the operation in the embodiment of FIG. 2. . 1-Optical fiber, 11--Reference clock source, 12-Clock generation circuit, 13--Speed conversion circuit, 14-Hybrid, I5--Driver, 16--LED element, 17-Receiver, 18-Timing Extraction circuit, 19-Frame synchronization circuit, 20-Speed conversion circuit, 21-・LED element, 22-Receiver, 23-・Synchronization separation circuit, 24-Clock generation circuit, 25.26-・Speed conversion circuit, 27- ·driver

Claims (1)

[Claims] A data superimposing means (101) for superimposing digital data on the vertical blanking period of the video signal and transmitting the data on the transmitting side and the receiving side of a system for transmitting a video signal via an optical fiber. Data separating means (102) for separating digital data from the superimposed signal is provided on the transmitting side, and data transmitting means (103) for sending the digital data during the vertical blanking period of the video signal. ) is provided on the receiving side, and data receiving means (104) for receiving the digital data is provided on the receiving side.
) is provided on the transmitting side.