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US 5,710,649 AGranted
Apparatus and methods for nulling non-random timing jitter in the transmission of digital optical signals
AssigneeLucent Technologies Inc.
InventorLinn Frederick Mollenauer
Life of this patent
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Abstract
A clock recovery circuit for following rapid changes in the time phase of a data stream is disclosed. The circuit comprises a low Q resonator coupled to a detection device, such as an electro-optic modulator in a time division demultiplexer or a decision circuit of a receiver. Preferably, a high Q resonator or phase locked oscillator is provided, as well. The present invention is particularly useful in a telecommunications system for transmitting solitons. A method of compensating for changes in time phase of a data stream is also disclosed.
Claims39
A clock recovery circuit for use in a telecommunications system, the circuit comprising:
- a signal splitter having an input and a first and second output, the signal splitter splitting an electrical signal into first and second electrical signals;
- a low Q resonator having an output and an input coupled to the first output of the splitter;
- a high Q resonator or phase locked oscillator having an output and an input coupled to the second output of the splitter;
- a combiner having an output and a first input coupled to the output of the low Q resonator and a second input coupled to the output of the high Q resonator or phase locked oscillator, wherein the output of the combiner is a sinusoidal signal whose phase is correlated to the phase of a signal stream provided to the input of the signal splitter, to synchronize time acceptance windows for a detection device with shifts in arrival times of bits of a signal stream.
1 more element
A clock recovery circuit for use in a telecommunications system comprising a detection device for detecting a transmitted signal, the circuit comprising:
- first means for following rapid changes in phase of a signal and providing an output indicative of those changes;
- second means for following slow changes in the phase of a signal and providing an output indicative of those changes;
- and
- means for combining the outputs of the first and second means and providing an output to synchronize time acceptance windows for the detection device with shifts in arrival times of bits of the signal.
1 more element
A time division demultiplexer for use in a telecommunications system, the demultiplexer comprising:
- an input;
- a first signal splitter coupled to the input of the time division demultiplexer, the splitter having first and second outputs, the splitter splitting an optical signal into first and second optical signals;
- a detector having an output and an input coupled to the first output of the splitter;
- a low Q resonator having an output and an input coupled to the output of the detector, wherein the output of the low Q resonator is a sinusoidal signal whose phase is correlated to the phase of the signal stream provided to the first splitter;
- and
- a plurality of electro-optic modulators each having first and second inputs, wherein the output of the low Q resonator is coupled to the first input of each of the modulators and the second output of the first splitter is coupled to the second input of each of the modulators, to synchronize the time acceptance windows of the modulators with shifts in arrival times of bits of the optical signal at the second input of the modulators.
3 more elements
A receiver for use in a telecommunications system, the receiver comprising:
- an input;
- a first signal splitter coupled to the input of the receiver, the first signal splitter having an input and a first and second output, the splitter splitting an optical signal into first and second optical signals;
- a detector having an output and an input coupled to the first output of the splitter;
- a low Q resonator having an output and an input coupled to the first output of the detector, wherein the output of the low Q resonator is a sinusoidal signal whose phase is correlated to the phase of a signal stream provided to the first signal splitter;
- and
- a decision circuit having first and second inputs, wherein the output of the low Q resonator is coupled to the first input of the decision circuit and the output of the first splitter is coupled to the second input of the decision circuit, such that time acceptance windows of the decision circuit are synchronized with shifts in arrival times of bits of the signal stream at the input of the decision circuit.
3 more elements
A telecommunications system comprising:
- at least one transmitter transmitting a time division multiplexed optical signal;
- a transmission medium comprising an input and an output, the input of the transmission medium being coupled to the transmitter;
- at least one time division demultiplexer coupled to the output of the transmission medium, wherein the time division demultiplexer comprises a clock recovery circuit which follows rapid changes in phase of the optical signal;
- and
- at least one receiver.
2 more elements
A telecommunications system comprising:
- a plurality of transmitters, each transmitter transmitting an optical signal at a different wavelength;
- a transmission medium comprising an input and an output;
- a wavelength division multiplexer having inputs coupled to the plurality of transmitters and an output coupled to the input of the transmission medium;
- a wavelength division demultiplexer having an input and outputs, the input of the demultiplexer being coupled to the output of the transmission medium;
- a plurality of time division demultiplexers having inputs and outputs, wherein each of the time division demultiplexers comprises a clock recovery circuit which follows rapid changes in phase of its corresponding optical signal;
- a plurality of receivers;
- wherein the outputs of the wavelength division demultiplexer are coupled to the inputs of the plurality of time division demultiplexers and the outputs of the time division demultiplexers are coupled to the plurality of receivers.
4 more elements
A telecommunications system comprising:
- at least one transmitter;
- a transmission medium comprising an output and an input, said at least one transmitter coupled to the input of the transmission medium;
- a decision circuit;
- and
- at least one receiver coupled to the output of the transmission medium, the receiver comprising a clock recovery circuit which follows rapid changes in phase of an optical signal coupled to the decision circuit.
2 more elements
A telecommunications system comprising:
- a plurality of transmitters each producing an optical signal at an output;
- a wavelength division multiplexer coupled to the plurality of transmitters;
- a transmission medium comprising an output and an input coupled to the wavelength division multiplexer;
- a decision circuit;
- a wavelength division demultiplexer having inputs and an output, the input of the demultiplexer being coupled to the output of the transmission medium and the output of the demultiplexer being coupled to at least one receiver comprising a clock recovery circuit which follows rapid changes in phase of an optical signal coupled to the decision circuit.
2 more elements
A method of compensating for changes in the phase of a transmitted optical signal in a telecommunications system, the method comprising:
- following rapid changes in the phase of the transmitted signal;
- providing a first signal indicative of those changes;
- and
- synchronizing time acceptance windows of a detection device with shifts in arrival times of bits of the transmitted signal based on the first signal.
1 more element
A method of compensating for changes in the phase of a transmitted optical signal in a telecommunications system, the method comprising:
- following rapid changes in the phase of the transmitted signal;
- providing a first signal indicative of those changes;
- synchronizing time acceptance windows of a detection device with shifts in arrival times of bits of the transmitted signal based on the first signal;
- following slow changes in the phase of the transmitted signal;
- providing a second signal indicative of the slow changes;
- summing the first and second signals;
- and
- synchronizing time acceptance windows of the detection device based on the sum of the first and second signals.
5 more elements
Dependencies are inferred from the claim text.