Method for transmission and receipt of coherent light signals
First Claim
Patent Images
1. A method for transmission and receipt of coherent light signals, comprising the steps of:
- providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers;
providing an oscillation light signal having a first predetermined wavelength in one of said subscribers;
transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station;
transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers;
combining said second light signal and said oscillation light signal to provide an intermediate light signal;
converting said intermediate light signal to an intermediate electric signal; and
demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers, wherein;
at least one of said oscillation light signal and said first light signal is used to correct a reference wavelength during a non-communication state between said station and said one of said subscribers, and wherein a wavelength of said first light signal is set based on said reference wavelength during a communication state between said station and said one of said subscribers.
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Abstract
Each subscriber is provided with an optical heterodyne detection circuit. An oscillation light of an optical local oscillator is divided to a local oscillation light for the heterodyne detection and a transmitting light for data communication. A channel for those lights is selected from vacant communication channels. The transmitting light may be obtained from a transmission light oscillator which is controlled by a control unit common to the optical local oscillator.
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Citations
7 Claims
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1. A method for transmission and receipt of coherent light signals, comprising the steps of:
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providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers; providing an oscillation light signal having a first predetermined wavelength in one of said subscribers; transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station; transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers; combining said second light signal and said oscillation light signal to provide an intermediate light signal; converting said intermediate light signal to an intermediate electric signal; and demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers, wherein; at least one of said oscillation light signal and said first light signal is used to correct a reference wavelength during a non-communication state between said station and said one of said subscribers, and wherein a wavelength of said first light signal is set based on said reference wavelength during a communication state between said station and said one of said subscribers.
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2. A method for transmission and receipt of coherent light signals, comprising the steps of:
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providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength division multiplexing via optical fibers; providing an oscillation light having a first predetermined wavelength which light is divided into first and second light signals at one of said subscribers; transmitting over a common signaling channel said first light signal from said one of said subscribers to said station; transmitting over said common signaling channel a third light signal having a second predetermined wavelength from said station to said one of said subscribers; combining said second light signal and said third light signal to provide an intermediate light signal; converting said intermediate light signal to an intermediate electric signal; demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers, wherein; said first and third light signals are assigned to a common signaling channel only during a non-communication state and during an initial stage of a communication state.
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3. A method for transmission and receipt of coherent light signals, comprising the steps of:
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providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength division multiplexing by optical fibers; providing an oscillation light having a first wavelength which light is divided into first and second light signals at one of said subscribers; transmitting over a common signaling channel said first light signal from said one of said subscribers to said station; transmitting over said common signaling channel a third light signal having a second wavelength from said station to said one of said subscribers; combining said second light signal and said third light signal to provide an intermediate light signal; converting said intermediate light signal into an intermediate electric signal; demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers; shifting said first and second light signals to have a third wavelength and said third light signal, to have a fourth wavelength; and assigning said first and third shifted light signals to a communication channel different from said common signaling channel selected from vacant communication channels, wherein; said first light signal having said first wavelength and said third light signal having said second wavelength are assigned to said common signaling channel only during a non-communication state and during an initial stage of a communication state. - View Dependent Claims (4)
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5. A method for transmission and receipt of coherent light signals, comprising the steps of:
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providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers; providing an oscillation light signal having a first predetermined wavelength in one of said subscribers; transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station; transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers; combining said second light signal and said oscillation light signal to provide an intermediate light signal; converting said intermediate light signal to an intermediate electric signal; demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers; and supplying said first light signal to a transmission member having a predetermined wavelength property to provide transmission peaks equal to a wavelength division of communication channels, said first light signal being swept in wavelength to be set to one of said communication channels-by counting said transmission peaks.
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6. A method for transmission and receipt of coherent light signals, comprising the steps of:
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providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers; providing an oscillation light signal having a first predetermined wavelength in one of said subscribers; transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station; transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers; combining said second light signal and said oscillation light signal to provide an intermediate light signal; converting said intermediate light signal to an intermediate electric signal; demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers; controlling said first and second predetermined wavelengths using a wavelength of a common signaling channel as a reference wavelength; and setting up a line connection between said one of said subscribers and another subscriber on a channel different from said common signaling channel;
wherein;said second predetermined wavelength is for an up line signal and said third predetermined wavelength is for a down line signal.
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7. A method for transmission and receipt of coherent light signals, comprising the steps of:
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providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers; providing an oscillation light signal having a first predetermined wavelength in one of said subscribers; transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station; transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers; combining said second light signal and said oscillation light signal to provide an intermediate light signal; converting said intermediate light signal to an intermediate electric signal; demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers; assigning said first predetermined wavelength to a common signaling channel; controlling a beat frequency between said oscillation light signal and said first light signal to be a predetermined value; and setting up a line connection between said one of said subscribers and a designated subscriber of said subscribers on a channel different from said common signaling channel.
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Specification