Maintenance of optical networks

Claim 2

Apparatus disposed along a transmission line for adding a dither signal to an optical carrier modulated with an information signal, comprising: a dithering element having an input and an output disposed in series with the transmission line carrying the optical carrier modulated with the information signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; a signal generator for producing a desired dither signal to be added to the modulated optical carrier, the dither signal generator being coupled to the non-inverting input of the differential element; and a feedforward element for coupling a signal at the input of the dithering element to the inverting input of the differential element.

Claim 3

Apparatus disposed along a transmission line for removing a dither signal from an optical carrier modulated with an information signal, comprising: a dithering element having an input and an output disposed in series with the transmission line for receiving the optical carrier modulated with the information signal and containing a dither signal and for processing the optical carrier to remove the dither signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; and a feedforward element for coupling a signal at the input of the dithering element to the inverting input of the differential element.

Claim 4

Apparatus disposed along a transmission line for removing a dither signal from an optical carrier modulated with an information signal, comprising: a dithering element having an input and an output disposed in series with the transmission line for receiving the optical carrier modulated with the information signal and containing a dither signal and for processing the optical carrier to remove the dither signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; and a feedforward element for coupling a signal at the input of the dithering element to the inverting input of the differential element.

Claim 5

Apparatus disposed along a transmission line for regenerating a dither signal in an optical carrier modulated with an information signal, comprising: a dithering element having an input and an output in series with the transmission line carrying the optical carrier modulated with the information signal and containing a dither signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; a signal generator for producing a replica of the dither signal and coupling the replica of the dither signal to the non-inverting input of the differential element; and a feedforward element for coupling a signal at the input of the dithering element to the inverting input of the differential element.

Claim 6

Apparatus disposed along a transmission line for regenerating a dither signal in an optical carrier modulated with an information signal, comprising: a dithering element having an input and an output in series with the transmission line carrying the optical carrier modulated with the information signal and containing a dither signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; a signal generator for producing a replica of the dither signal and coupling the replica of the dither signal to the non-inverting input of the differential element; and a feedforward element for coupling a signal at the input of the dithering element to the inverting input of the differential element.

Claim 7

Apparatus disposed along a transmission line for replacing a first dither signal in an optical carrier modulated with an information signal with a second dither signal, comprising: a dithering element having an input and an output in series with the transmission line carrying the optical carrier modulated with the information signal and containing the first dither signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; a signal generator for producing the second dither signal and coupling the second dither signal to the non-inverting input of the differential element; and a feedforward element for coupling a signal at the input of the dithering element to the inverting input of the differential element.

Claim 8

Apparatus disposed along a transmission line for replacing a first dither signal in an optical carrier modulated with an information signal with a second dither signal, comprising: a dithering element having an input and an output in series with the transmission line carrying the optical carrier modulated with the information signal and containing the first dither signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; a signal generator for producing the second dither signal and coupling the second dither signal to the non-inverting input of the differential element; and a feedforward element for coupling a signal at the input of the dithering element to the inverting input of the differential element.

Claim 9

Apparatus disposed along a transmission line for selectively adding a dither signal to, removing a dither signal from, regenerating a dither signal in, or changing a dither signal in, an optical carrier modulated with an information signal, comprising: a dithering element having an input and an output in series with the transmission line carrying the optical carrier modulated with the information signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; a signal generator for producing a signal which selectively causes a dither signal to be added to the modulated optical carrier, a dither signal to be removed from the modulated optical carrier, a dither signal in the modulated optical carrier to be regenerated, a first dither signal in the modulated optical carrier to be replaced with a second dither signal, the signal produced by the signal generator being coupled to the non-inverting input of the differential element; and a feedforward element for producing a signal related to the input of a dithering element and coupling that signal to the inverting input of the differential element.

Claim 10

Apparatus disposed along a transmission line for selectively adding a dither signal to, removing a dither signal from, regenerating a dither signal in, or changing a dither signal in, an optical carrier modulated with an information signal, comprising: a dithering element having an input and an output in series with the transmission line carrying the optical carrier modulated with the information signal; a differential element having an inverting input, a non-inverting input, and an output coupled to the input of the dithering element; a signal generator for producing a signal which selectively causes a dither signal to be added to the modulated optical carrier, a dither signal to be removed from the modulated optical carrier, a dither signal in the modulated optical carrier to be regenerated, a first dither signal in the modulated optical carrier to be replaced with a second dither signal, the signal produced by the signal generator being coupled to the non-inverting input of the differential element; and a feedforward element for producing a signal related to the input of a dithering element and coupling that signal to the inverting input of the differential element.

Claim 11

Method of adding at a point along a transmission line a dither signal to an optical carrier modulated with an information signal, comprising the steps of: generating a desired dither signal to be added to the optical carrier modulated with the information signal; producing a feedforward signal related to the input of a dithering element in series with the transmission line for receiving the modulated optical carrier; producing a signal relating to the difference between the desired dither signal and the feedforward signal; and controlling the dithering element in response to the difference signal.

Claim 12

Method of adding at a point along a transmission line a dither signal to an optical carrier modulated with an information signal, comprising the steps of: generating a desired dither signal to be added to the optical carrier modulated with the information signal; producing a feedforward signal related to the input of a dithering element in series with the transmission line for receiving the modulated optical carrier; producing a signal relating to the difference between the desired dither signal and the feedforward signal; and controlling the dithering element in response to the difference signal.

Claim 13

Method of removing at a point along a transmission line a dither signal from an optical carrier modulated with an information signal, comprising the steps of: generating a constant level signal; producing a feedforward signal related to the input of a dithering element in series with the transmission line for receiving the optical carrier modulated with the information signal; producing a signal relating to the difference between the constant level signal and the feedforward signal; and controlling the dithering element in response to the difference signal to remove the dither signal from the optical carrier.

Claim 14

Method of removing at a point along a transmission line a dither signal from an optical carrier modulated with an information signal, comprising the steps of: generating a constant level signal; producing a feedforward signal related to the input of a dithering element in series with the transmission line for receiving the optical carrier modulated with the information signal; producing a signal relating to the difference between the constant level signal and the feedforward signal; and controlling the dithering element in response to the difference signal to remove the dither signal from the optical carrier.

Claim 15

Method of regenerating at a point along a transmission line a dither signal in an optical carrier modulated with an information signal, comprising the steps of: generating a replica of the dither signal in the optical carrier modulated with the information signal; producing a feedforward signal related to the input of a dithering element receiving the modulated optical carrier; producing a signal relating to the difference between the replica of the dither signal and the feedforward signal; and controlling the dithering element in response to the difference signal.

Claim 16

Method of regenerating at a point along a transmission line a dither signal in an optical carrier modulated with an information signal, comprising the steps of: generating a replica of the dither signal in the optical carrier modulated with the information signal; producing a feedforward signal related to the input of a dithering element receiving the modulated optical carrier; producing a signal relating to the difference between the replica of the dither signal and the feedforward signal; and controlling the dithering element in response to the difference signal.

Claim 17

Method of replacing at a point along a transmission line a dither signal in an optical carrier modulated with an information signal with another dither signal, comprising the steps of: generating a signal relating to a dither signal which will replace an existing dither signal already in the optical carrier modulated with the information signal; producing a feedforward signal related to the input of a dithering element receiving the modulated optical carrier; producing a signal relating to the difference between the feedforward signal and the signal produced as a result of the generating step; and controlling the dithering element in response to the difference signal.

Claim 18

Method of replacing at a point along a transmission line a dither signal in an optical carrier modulated with an information signal with another dither signal, comprising the steps of: generating a signal relating to a dither signal which will replace an existing dither signal already in the optical carrier modulated with the information signal; producing a feedforward signal related to the input of a dithering element receiving the modulated optical carrier; producing a signal relating to the difference between the feedforward signal and the signal produced as a result of the generating step; and controlling the dithering element in response to the difference signal.

Claim 19

Method of selectively adding a dither signal to, removing a dither signal from, changing a dither signal in, and regenerating a dither signal in, an optical carrier modulated with an information signal received over a transmission line, comprising the steps of: selecting one of a dither signal to be added to the optical carrier modulated with the information signal, a constant level signal, a dither signal to be substituted for another dither signal in the modulated optical carrier, and a replica of a dither signal in the modulated optical carrier; producing a feedforward signal related to the input of a dithering element receiving the modulated optical carrier; producing a signal relating to the difference between the feedforward signal and a signal selected from the group consisting of the dither signal to be added, the constant level signal, the dither signal to be substituted, and the replica of the dither signal; and controlling the dithering element in response to the difference signal.

Claim 20

Method of selectively adding a dither signal to, removing a dither signal from, changing a dither signal in, and regenerating a dither signal in, an optical carrier modulated with an information signal received over a transmission line, comprising the steps of: selecting one of a dither signal to be added to the optical carrier modulated with the information signal, a constant level signal, a dither signal to be substituted for another dither signal in the modulated optical carrier, and a replica of a dither signal in the modulated optical carrier; producing a feedforward signal related to the input of a dithering element receiving the modulated optical carrier; producing a signal relating to the difference between the feedforward signal and a signal selected from the group consisting of the dither signal to be added, the constant level signal, the dither signal to be substituted, and the replica of the dither signal; and controlling the dithering element in response to the difference signal.

Claim 21

Apparatus disposed along a transmission line for adding a dither signal to an optical carrier modulated with an information signal, comprising: a dithering element having an optical input and output disposed along the transmission line carrying the optical carrier and having an electrical input for modulating the optical carrier with a desired dither signal; a differential amplifier having an inverting input, a non-inverting input, and an output coupled to the electrical input of the dithering element; a signal generator for producing the desired dither signal to be added to the modulated optical carrier, the dither signal generator being coupled to the non-inverting input of the differential amplifier, and a feedforward element for producing a signal related to the input of the dithering element and coupling that signal to the inverting input of the differential amplifier.

Claim 22

Apparatus disposed along a transmission line for adding a dither signal to an optical carrier modulated with an information signal, comprising: a dithering element having an optical input and output disposed along the transmission line carrying the optical carrier and having an electrical input for modulating the optical carrier with a desired dither signal; a differential amplifier having an inverting input, a non-inverting input, and an output coupled to the electrical input of the dithering element; a signal generator for producing the desired dither signal to be added to the modulated optical carrier, the dither signal generator being coupled to the non-inverting input of the differential amplifier, and a feedforward element for producing a signal related to the input of the dithering element and coupling that signal to the inverting input of the differential amplifier.

Claim 23

Apparatus disposed along a transmission line for removing an undesired dither signal from an optical carrier modulated with an information signal, comprising: a dithering element having an optical input and output disposed in series with the transmission line carrying the optical carrier and having an electrical input for modulating the optical carrier with an inverted replica of the undesired dither signal to remove the undesired dither signal; an inverting amplifier having an output coupled to the electrical input of the dithering element; and a feedforward element for producing a signal related to the amplitude of the undesired dither signal at the input of the dithering element and coupling that signal to the inverting amplifier.

Claim 24

Apparatus disposed along a transmission line for removing an undesired dither signal from an optical carrier modulated with an information signal, comprising: a dithering element having an optical input and output disposed in series with the transmission line carrying the optical carrier and having an electrical input for modulating the optical carrier with an inverted replica of the undesired dither signal to remove the undesired dither signal; an inverting amplifier having an output coupled to the electrical input of the dithering element; and a feedforward element for producing a signal related to the amplitude of the undesired dither signal at the input of the dithering element and coupling that signal to the inverting amplifier.

Claim 25

Apparatus disposed along a transmission line for regenerating a dither signal in an optical carrier modulated with an information signal, comprising: a dithering element having an optical input and output in series with the transmission line carrying the optical carrier and having an electrical input for modulating the optical carrier with a desired dither signal; a differential amplifier having an inverting input, a non-inverting input, and an output coupled to the electrical input of the dithering element; a signal generator for producing a replica of the dither signal contained in the optical carrier and coupling the replica of the dither signal to the non-inverting input of the differential amplifier; and a feedforward element for producing a signal related to the amplitude of the dither signal at the input of the dithering element and coupling that signal to the inverting input of the differential amplifier.

Claim 26

Apparatus disposed along a transmission line for regenerating a dither signal in an optical carrier modulated with an information signal, comprising: a dithering element having an optical input and output in series with the transmission line carrying the optical carrier and having an electrical input for modulating the optical carrier with a desired dither signal; a differential amplifier having an inverting input, a non-inverting input, and an output coupled to the electrical input of the dithering element; a signal generator for producing a replica of the dither signal contained in the optical carrier and coupling the replica of the dither signal to the non-inverting input of the differential amplifier; and a feedforward element for producing a signal related to the amplitude of the dither signal at the input of the dithering element and coupling that signal to the inverting input of the differential amplifier.

Claim 27

Apparatus disposed along a transmission line for replacing a first dither signal contained in an optical carrier modulated with an information signal with a second dither signal, comprising: a dithering element having an optical input and output in series with the transmission line carrying the optical carrier containing the first dither signal and having an electrical input for modulating the optical carrier with the second dither signal; a differential amplifier having an inverting input, a non-inverting input, and an output coupled to the electrical input of the dithering element; a signal generator for producing the second dither signal and coupling the second dither signal to the non-inverting input of the differential amplifier; and a feedforward element for producing a signal related to the amplitude of the first dither signal contained in the optical carrier at the input of the dithering element and coupling that signal to the inverting input of the differential amplifier.

Claim 28

Apparatus disposed along a transmission line for replacing a first dither signal contained in an optical carrier modulated with an information signal with a second dither signal, comprising: a dithering element having an optical input and output in series with the transmission line carrying the optical carrier containing the first dither signal and having an electrical input for modulating the optical carrier with the second dither signal; a differential amplifier having an inverting input, a non-inverting input, and an output coupled to the electrical input of the dithering element; a signal generator for producing the second dither signal and coupling the second dither signal to the non-inverting input of the differential amplifier; and a feedforward element for producing a signal related to the amplitude of the first dither signal contained in the optical carrier at the input of the dithering element and coupling that signal to the inverting input of the differential amplifier.

Claim 29

Method of adding at a point along a transmission line a dither signal to an optical carrier modulated with an information signal, comprising the steps of: generating a desired dither signal to be added to the optical carrier modulated with the information signal; modulating the optical carrier with the desired dither signal; producing a feedforward signal related to the input of a dithering element in series with the transmission line for receiving the modulated optical carrier; producing a signal relating to the difference between the desired dither signal and the feedforward signal; and controlling the dithering signal modulated onto the optical carrier in response to that difference signal.

Claim 30

Method of adding at a point along a transmission line a dither signal to an optical carrier modulated with an information signal, comprising the steps of: generating a desired dither signal to be added to the optical carrier modulated with the information signal; modulating the optical carrier with the desired dither signal; producing a feedforward signal related to the input of a dithering element in series with the transmission line for receiving the modulated optical carrier; producing a signal relating to the difference between the desired dither signal and the feedforward signal; and controlling the dithering signal modulated onto the optical carrier in response to that difference signal.

Claim 31

Method of removing at a point along a transmission line an undesired dither signal from an optical carrier modulated with an information signal, comprising the steps of: generating an inverted replica of the undesired dither signal contained in the optical carrier; modulating the optical carrier with the inverted replica of the undesired dither signal; producing a feedforward signal related to the amplitude of the undesired dither signal in the modulated optical carrier; controlling the amplitude of the inverted replica of the undesired dither signal modulated onto the optical carrier in response to the feedforward signal.

Claim 32

Method of removing at a point along a transmission line an undesired dither signal from an optical carrier modulated with an information signal, comprising the steps of: generating an inverted replica of the undesired dither signal contained in the optical carrier; modulating the optical carrier with the inverted replica of the undesired dither signal; producing a feedforward signal related to the amplitude of the undesired dither signal in the modulated optical carrier; controlling the amplitude of the inverted replica of the undesired dither signal modulated onto the optical carrier in response to the feedforward signal.

Claim 33

Method of regenerating at a point along a transmission line a dither signal in an optical carrier modulated with an information signal, comprising the steps of: generating a replica of the dither signal contained in the optical carrier; modulating the optical carrier with the replica of the dither signal; producing a feedforward signal related to the amplitude of the dither signal modulated onto the optical carrier; producing a signal relating to the difference between the desired amplitude of the replica of the dither signal and the feedforward signal; and controlling the amplitude of the replica of the dither signal modulated onto the carrier in response to the difference signal.

Claim 34

Method of regenerating at a point along a transmission line a dither signal in an optical carrier modulated with an information signal, comprising the steps of: generating a replica of the dither signal contained in the optical carrier; modulating the optical carrier with the replica of the dither signal; producing a feedforward signal related to the amplitude of the dither signal modulated onto the optical carrier; producing a signal relating to the difference between the desired amplitude of the replica of the dither signal and the feedforward signal; and controlling the amplitude of the replica of the dither signal modulated onto the carrier in response to the difference signal.

Claim 35

Method of replacing at a point along a transmission line an undesired first dither signal contained in an optical carrier with a desired second dither signal, the optical carrier being modulated with an information signal, the method comprising the steps of: generating an inverted replica of the undesired first dither signal and generating the desired second dither signal; modulating the optical carrier with the inverted replica of the undesired first dither signal and the desired second dither signal; producing a feedforward signal related to the amplitude of the undesired first dither signal modulated onto the optical carrier; producing a signal relating to the difference between the feedforward signal and the desired second dither signal; and controlling the amplitude of the signals produced in the generating step in response to the difference signal.

Claim 36

Method of replacing at a point along a transmission line an undesired first dither signal contained in an optical carrier with a desired second dither signal, the optical carrier being modulated with an information signal, the method comprising the steps of: generating an inverted replica of the undesired first dither signal and generating the desired second dither signal; modulating the optical carrier with the inverted replica of the undesired first dither signal and the desired second dither signal; producing a feedforward signal related to the amplitude of the undesired first dither signal modulated onto the optical carrier; producing a signal relating to the difference between the feedforward signal and the desired second dither signal; and controlling the amplitude of the signals produced in the generating step in response to the difference signal.