Patent ID: 6490063
Filing Date: 2002-12-03
Classification: H04B

Abstract:
An analog optical transmission system for bilateral communication of analog optical signals using two-route optical fibers, uplink and downlink, between a Master unit and a Slave unit;said Master unit comprising: an oscillator for oscillating a monitoring signal having a frequency different from that of an information signal to be transmitted to said Slave unit; a Master composition means for synthesizing an information signal to be transmitted to said Slave unit and said monitoring signal oscillated by said oscillator; a Master light emission means for converting a synthesized signal output from said Master composition means into an analog optical signal and then transmitting said analog optical signal to said Slave unit via a downlink optical fiber; a Master light reception means for receiving analog optical signals transmitted from said Slave unit via an uplink optical fiber; an average received-light level detection means for detecting an average received-light level of analog optical signals received by said Master light reception means; a Master filter means for separating signals having a frequency corresponding to said monitoring signal from analog optical signals received by said Master light reception means; and a monitoring signal-level detection means for detecting a level of said signals separated by said Master filter means; said Slave unit comprising: a Slave light reception means for receiving analog optical signals transmitted from said Master unit via said downlink optical fiber; a Slave filter means for separating signals having a frequency corresponding to said monitoring signal from analog optical signals received by said Slave light reception means; a Slave composition means for synthesizing said signals separated by said Slave filter means and an information signal to be transmitted to said Master unit; and a Slave light emission means for converting a synthesized signal output from said Slave composition means into an analog optical signal having a constant average optical power and then transmitting said analog optical signal to said Master unit via said uplink optical fiber; wherein it is thus possible to detect an fault by specifying which of said uplink optical fiber or downlink optical fiber includes the fault based on fluctuations in an average received-light level detected by said average received-light level detection means fo said Master unit and fluctuations in a level detected by said monitoring signal-level detection means.