Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1999-07-16
2002-12-03
Pascal, Leslie (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200, C359S199200
Reexamination Certificate
active
06490063
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to an analog optical transmission system, a Master unit and a Slave unit which transmit analog optical signals from the Master unit to the Slave unit via a downlink optical fiber and also does so from the Slave unit to the Master unit via an uplink optical fiber, and more particularly, to technologies whereby faults occurring on the uplink or downlink optical fiber can be detected by the Master unit or a user who monitors the Master unit, even if the Slave unit should not detect the faults on the downlink optical fiber.
2. Related Art
Optical fibers, for example, are well known as low-loss transmission lines through which optical signals can be transferred and have been utilized in various optical communication fields. Although the optical transmission system utilizing such optical fibers as transmission lines can transfer optical signals efficiently as above-mentioned, a normal optical communication cannot be performed, if transmission is loss is increased or optical signals are interrupted by damage, disconnection, or cut-off on the optical fiber. Thus, in an optical transmission system, the monitor on transmission faults is performed, for example, on real-time about whether damage of optical fibers used as transmission lines are caused or not, and such monitoring is very important from the point of system reliability.
In the optical transmission system that transmits respective optical signals from the Master unit to the Slave unit via a downlink optical fiber and from the Slave unit to: the Master unit via an uplink optical fiber, the communication is performed using a communication circuit for control between a CPU of a microcomputer or the like equipped in the Master unit and a CPU of a microcomputer or the like equipped in the Slave unit so that the Master unit monitors states of each processing section of the Slave unit and controls the gain thereof.
In the analog optical transmission systems with such a configuration, the Master unit, for example, monitors the uplink optical fiber, while the Slave unit monitors the downlink optical fiber. If a fault of the downlink optical fiber is detected, the Slave unit may inform it to the Master unit using the above-mentioned communication circuit. More specifically, in monitoring in the Slave unit, when receiving analog optical signals transmitted from the Master unit via the downlink optical fiber, the CPU always monitors the level of the received light of the concerned light reception element, and if a fault of the downlink optical fiber is detected by the CPU, it may be informed to the CPU of the Master unit.
On the other hand, the Master unit, when notified of the fault of the downlink optical fiber by the Slave unit, outputs a warning alarm of the fault to the user.
However, the above-mentioned analog optical transmission system suffers from such drawback that, although the Master unit can monitor the uplink optical fiber as above-mentioned, the downlink optical fiber must be monitored by the Slave unit and the monitoring results must be informed to the Master unit, thus both the Master and Slave units must monitor the optical fibers.
Specifically, such types of analog optical transmission systems have a drawback of a complicated configuration for monitoring optical fibers, because it is necessary to create communication protocols for, for example, informing the monitoring results from the Slave unit to the Master unit, to provide with both the Master and Slave units control programs to be executed by the CPU for processings of such information and the monitoring of optical fiber, and also to equip the above-mentioned controlling communication circuits. Such drawback is particularly conspicuous in those systems that may not need to execute control between the Master and Slave units besides the above-mentioned optical fiber monitoring and informing processings, and there has been an urgent need for a simple monitoring configuration that allows execution of the monitoring of two-route optical fibers only by, for example, the Master unit.
To solve those problems of the prior arts, the present invention has an object to provide an analog optical transmission system as well as the related Master and Slave units that enable the Master unit or the user who monitors the Master unit to detect faults of the uplink or downlink optical fiber even if there is no need, for example, for the Slave unit to monitor the downlink optical fiber, in such a case where the bilateral communication of analog optical signals is performed by using two-route optical fibers between the Master and Slave units.
SUMMARY OF THE INVENTION
An analog optical transmission system according to the present invention is capable of detecting faults of optical fibers as follows when executing the bilateral communication of analog optical signals by use of two-route optical fibers, uplink and downlink, between the Master and Slave units:
That is, while the Master unit has the Master light emission means for transmitting a prescribed monitoring optical signal to the Slave unit via the downlink optical fiber, the Slave unit has the Slave light reception means for receiving the abovementioned monitoring optical signal sent from the Master unit via the downlink optical fiber. The Slave light emission means returns the above-mentioned monitoring optical signals received by the Slave light reception means to the Master unit via the uplink optical fiber. Then, in the Master unit, its light reception means receives the above-mentioned monitoring optical signal returned from the Slave unit via the uplink optical fiber, allowing a monitoring signal-level detection means to detect the level of the above-mentioned monitoring optical signal received by the Master light reception means.
Thus, it is possible to detect faults of the optical fibers based on fluctuations in the level detected by the monitoring signal-level detection means. More specifically, if, for example, the level of the above-mentioned monitoring optical signal detected by the Master unit is lower than a normal reference level, it is possible to determine that a fault occurs at least one of the uplink and downlink optical fibers, so that such a configuration is effective in a case where it is requested only to detect any faults of either the uplink or downlink optical fiber and there is no need to determine which of the two fibers has a trouble.
Moreover, prescribed monitoring optical signals described herein may include any signal depending on the service conditions of, for example, the system as well as the Master or Slave unit.
In addition to the above-mentioned analog optical transmission systems, the present invention provides such Master and Slave units as above-mentioned.
That is, in bilateral communication of analog optical signals by use of two-route optical fibers, uplink and downlink, between a Master and Slave units, the Master unit according to the present invention has its light emission means for transmitting a prescribed monitoring optical signal to the Slave unit via the downlink optical fiber and the Master light reception means receive the above-mentioned monitoring optical signal returned from the Slave unit via the uplink optical fiber. The monitoring signal-level detection means detects the level of the above-mentioned monitoring optical signal received by the Master light reception means, thereby enabling to detect faults of the optical fibers based on the fluctuations in the level detected by the monitoring signal-level detection means.
On the other hand, the Slave unit according to the present invention, when executing bilateral communication of analog optical signals by use of two-route optical fibers, uplink and downlink, between the Master and Slave units, has the Slave light reception means for receiving the prescribed monitoring optical signal transmitted from the Master unit via the downlink optical fiber and the Slave light emission means for returning the above-mentioned monitoring optica
Kokusai Electric Co. Ltd.
Pascal Leslie
Phan Hanh
Wenderoth , Lind & Ponack, L.L.P.
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