JPS61174838A - Optical transmitter and receiver - Google Patents

Abstract

PURPOSE:To grasp the reception condition in the transmission station side by reflecting an optical signal transmitted from the transmission station side and turning back this signal to the transmission side if the reception state is abnormal. CONSTITUTION:An optical transmitter 2 in a transmission station A converts the input electric signal to an optical signal and inputs the optical signal to a terminal 61 of an optical directional coupler 6. The optical signal output from a terminal 62 is inputted to a transmission/reflection switch 8 of a reception station B through an optical fiber transmission line. If the reception station does not receive the signal, the optical signal from the transmission line 1 is reflected by the switch 8 and is turned back to the transmission station A. The turned-back optical signal is inputted to an alarm 10 through an optical receiver 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical transmitter/receiver for an optical fiber transmission system.

Conventional technology Figure 3 shows a conventional center station that connects point A of the transmitting station and point B of the terminal station or receiving station through a single optical fiber transmission line 1.
This shows part of a simple model of a single-wire bidirectional transmission system connected by . At points A and B, respectively, there are optical transmitters 2 and 3 that convert electrical signals into optical signals, and optical receivers 4 and 3 that convert optical signals into electrical signals, as devices for bidirectional optical transmission. It is equipped with 6. Further, in order to perform bidirectional communication using the single optical fiber transmission line 1, optical directional couplers 6 and 7 are respectively provided.

The optical directional couplers 6 and 7 output the optical signals from the optical transmitters 2 and 3 at respective points to the optical fiber transmission line 1, but the optical signals from the optical transmitters at the same point output to the optical fiber transmission line 1. It is never input to the optical receiver. Further, for the optical directional couplers 6 and 7, optical demultiplexing/multiplexers may be used in which the electro-optical conversion elements (light-emitting elements) used in the optical transmitters 2 and 3 are made to have different emission wavelengths.

With bidirectional transmission in this way, transmitting station A can communicate with receiving station B.
It is also possible to constantly monitor the status of

In other words, receiving station B will be transmitting station A unless there is an abnormality such as a power outage.
It is possible to notify transmitting station A that it is receiving a signal from station A.

Problems to be Solved by the Invention However, the above-mentioned information is unidirectional and only received by the receiving station B.
Even in the case of a system configuration in which transmitting station A only needs to be able to determine whether the optical transmitter is in a receiving state or not, or whether it is receiving a signal normally, in the conventional configuration, receiving station B has optical transmitter 3 and A directional coupler 7 is required.

The present invention has a very simple configuration that allows the transmitting station to monitor the status of the receiving station.

Means to Solve the Problem The present invention provides that when the receiving station is not in a receiving state or when the receiving state is abnormal, the optical signal sent from the transmitting station is reflected back to the transmitting station. By returning the optical signal, the transmitting station can grasp the reception status.

Effect: If the optical signal sent from the transmitting station is not received by the optical receiver at the receiving station, the receiving station reflects this optical signal back to the transmitting station, and the transmitting station receives the optical signal. Upon detection, the transmitting station can notify that the receiving station is not in the receiving state. Furthermore, if the optical receiver at the receiving station is operating normally, but a device other than the first receiver is malfunctioning, the optical signal level of the optical transmitter at the transmitting station may drop.
Embodiment 1 of the present invention is implemented by receiving the optical signal at the receiving station and changing the reflection period of the optical signal according to the abnormal situation, such as when the reception situation at the receiving station becomes abnormal. FIG. 2 is a block diagram showing one embodiment.

In FIG. 1, reference numeral 2 denotes an optical transmitter of transmitting station A, which converts an input electrical signal into an optical signal. ing.

In this optical directional coupler 6, the optical signal from the terminal 61 is
The signal is output toward the terminal 62, but not toward the terminal 63. Further, when an optical signal is input from the terminal 62, the optical signal input to the terminal 61 and the terminal 63 is branched and outputted.

The optical signal output from the terminal 62 of the optical directional coupler 6 passes through the optical fiber transmission line 1 and enters the transmissive-reflective optical switch 8 of the receiving station B.

An example of the basic structure of this transmissive-reflective switch 8 is shown in FIG. At the end of receiving station B of optical fiber transmission Fjlr1,
An optical signal is guided to the optical fiber core 1', and is converted by a converging rod lens 81 into an optical signal of parallel light having a large optical diameter. Reference numeral 82 denotes a light reflecting mirror, which is pulled up by a spring 83, and when a relay 84 operates, the light reflecting mirror 82 is pulled down as shown by arrow C. Therefore, when the relay 84 operates, the optical signal from the focusing rod lens 81 enters the focusing rod lens 85 and is transmitted to the optical receiver 5.
is input.

If receiving station B is not in reception state intentionally or is not receiving data due to a power outage, the focusing rod lens 8
The optical signal from 1 is reflected by the light reflecting mirror 82, returns to the focusing rod lens 81 again, and returns to the transmitting station B through the optical fiber core 1' and the optical fiber transmission line 1. This returned optical signal is sent to the optical directional coupler 6
The optical signal is converted and amplified into an electrical signal by the optical receiver 4 and then enters the annunciator 10.

Various types of alarm device 10 can be considered, but a simple one, for example, is one that uses a flashing LED lamp to notify the user.

Therefore, if the LED lamp of the annunciator 1o is lit, it will notify that the receiving station B is not in the receiving state.

Furthermore, if receiving station B is in a receiving state but the optical signal output level of the optical transmitter 2 of transmitting station A has decreased and receiving station B's receiving state is poor, or if receiving station B is in a good receiving state but is not connected to another In the event that a device being operated breaks down, etc., the above-mentioned status input signal is input to the input of the switch control circuit 11.

The output of this switch control circuit 11 is connected to the relay 84 of the transmission/reflection optical switch 8, and the operating cycle of the relay 84 is set depending on the type of each state input signal. From the above, the transmitting station A can monitor the status of the receiving station B based on the blinking period of the LED of the annunciator 1o.

Effects of the Invention As described above, according to the present invention, the reception status can be grasped on the transmitting station side with a simple configuration without providing the receiving station with an optical transmitter. Furthermore, in a CATV system using an optical fiber transmission line, since the reception time can be monitored at the center station, it can be easily applied as a billing system.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an optical transmitting/receiving device according to an embodiment of the present invention, Fig. 2 is a block diagram showing an example of the basic structure of a transmission/reflection calculation switch of the same device, and Fig. 3 is a conventional single-wire bidirectional transmission. It is a simplified model diagram of the system. 1... Optical fiber transmission line, 2... Optical transmitter, 4° 5... Optical receiver, 6... Optical directional coupler, 8 ...Transflective light switch, 1
0...Alarm, 11...Switch control circuit. Name of agent: Patent attorney Toshio Nakao and one other name
1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A transmitting station that includes an optical transmitter, a first optical receiver, and an optical directional coupler, and a second optical receiver that receives an optical signal sent from the transmitting station. An optical switch is provided in front of the second optical receiver and has a function of selectively reflecting the transmitted optical signal. A first optical receiver in the transmitting station receives the transmitted optical signal, and the transmitting station monitors the status of the receiving station. (2) The optical transmitting/receiving device according to claim 1, wherein the optical switch having a function of selectively reflecting an optical signal changes the reflection operation cycle depending on the situation of the receiving station.