Abstract: Methods and apparatuses are provided to modify existing overlay system architectures in a cost effective manner to meet the growing demand for narrowcast services and to position the existing overlay systems for additional future modifications. The implementations of the improved overlay system of this disclosure re-digitize narrowcast analog signals after they have been QAM modulated and upconverted to RF frequencies and replace the analog narrowcast transmitters with digital narrowcast transmitters. In the fiber nodes, the received narrowcast signals are converted back to analog signals and combined with analog broadcast signals for transmission to the service groups.

Abstract: A bi-directional optical transceiver includes multiple single mode optical ports and a multi-mode optical port. A multi-mode optical combiner combines single mode optical signals received at the single mode optical ports into a multi-mode optical signal at the multi-mode optical port. Each single mode optical signal has a distinct optical mode that does not interfere with the optical mode of the other single mode optical signals. A photo detector detects a total optical power of the plurality of single mode optical signals in the multi-mode optical signal. An amplifier is coupled to receive an output of the photo detector.

Abstract: An optical communication system includes logic to communicate using optical channels set outside a fiber zero dispersion zone, and having channel spacing that decreases with increasing distance from the fiber zero dispersion zone.

Abstract: Methods and systems for aggregating service groups are provided. A chain of fiber nodes in a DOCSIS system is formed to aggregate the service groups served by the fiber nodes to form a super-service group. Multiple channels of a multiplexed data stream are used to transmit the signals from the super-service group. By creating a chain of fiber nodes and using multiple channels to transmit the signals from the super-service group, a DOCSIS system can be more efficiently reconfigured to segment a super-service group once the system has become exhausted.

Abstract: One or more of a topology location test and a distance test are applied to determine if a CPE device has moved in a cable plant. An indication of service fraud is provided if the CPE topology location or distance test indicate an unauthorized CPE device move.

Abstract: A channel alignment system in an optical communication network includes logic to sample power of a quadrature amplitude modulation (QAM) channel at a component downstream from a QAM modulator. The system determines if the sampled channel power has a sufficient level. The system signals power control logic of the QAM modulator to adjust a gain of the sampled channel.

Abstract: Predistortion logic for an optical communications laser or optical modulator, includes predistortion logic embodied in a field programmable gate array (FPGA). A first analog to digital converter (ADC) provides a representation of an RF signal at an input of the FPGA. A digital to analog converter provides a representation of an output of the FPGA to a laser or modulator.

Abstract: Methods and apparatuses for controlling a bias point voltage for an external optical modulator are provided. A control loop is used to adjust a bias signal applied to an external modulator by determining unwanted signals at a predetermined frequency received by an optical receiver of the control loop and accounting for these unwanted signals when determining the bias point voltage.

Abstract: An RF attenuator circuit includes an anti-parallel PI structure having an input shunt arm comprising a single PIN diode, and an output shunt arm comprising a single PIN diode configured to have opposite polarity of the PIN diode of the input shunt arm.

Abstract: In a receiver suitable for an optical fiber link and comprising an optical receiver unit (1), which includes a radiation-sensitive detector (4) and a signal processing circuit (6,8), and an electrical receiver unit (2), the optical receiver unit comprises a power draining circuit (16) that drains power from a pull-up stage (R1-R4; Vpu) of the electrical receiver unit and supplies power to the electrical circuit of the optical receiver unit.

Abstract: A device includes an upsampling digital-analog converter (DAC) and logic to add a DC offset to a signal input to the DAC, the logic adapted to set the DC signal to cancel a DAC output spur.

Abstract: A system includes a laser generator, and a signal distortion generator circuit inline with the laser generator modulation signal and configured to generate distortion vectors in any of four distortion vector quadrants.

Abstract: An optical communication system includes logic to communicate using optical channels set outside a fiber zero dispersion zone, and having channel spacing that decreases with increasing distance from the fiber zero dispersion zone.

Abstract: A channel alignment system in an optical communication network includes logic to sample power of a quadrature amplitude modulation (QAM) channel at a component downstream from a QAM modulator. The system determines if the sampled channel power has a sufficient level. The system signals power control logic of the QAM modulator to adjust a gain of the sampled channel.

Abstract: An RF attenuator circuit includes an anti-parallel PI structure having an input shunt arm comprising a single PIN diode, and an output shunt arm comprising a single PIN diode configured to have opposite polarity of the PIN diode of the input shunt arm.

Abstract: Predistortion logic for an optical communications laser or optical modulator, includes predistortion logic embodied in a field programmable gate array (FPGA). A first analog to digital converter (ADC) provides a representation of an RF signal at an input of the FPGA. A digital to analog converter provides a representation of an output of the FPGA to a laser or modulator.

Abstract: A device includes an upsampling digital-analog converter (DAC) and logic to add a DC offset to a signal input to the DAC, the logic adapted to set the DC signal to cancel a DAC output spur.

Abstract: An optical receiver includes closed-loop composite second order (CSO) distortion correction logic. An optical communication system includes a transmitter comprising open-loop composite second order (CSO) distortion correction logic, and a receiver comprising closed-loop composite second order (CSO) distortion correction logic.

Abstract: A network device includes output rate control logic having variable bandwidth and a response time constant that increases according to an amount of time that an input rate of data to the network device is evaluated by the control logic.

Abstract: An optical-to-electrical converter may include and/or involve a splitter to separate one or more narrowcast signals from a broadcast signal, at least one broadcast signal receiver to receive the broadcast signal separated from one or more narrowcast signals, at least one narrowcast signal receiver to receive the narrowcast signal separated from the broadcast signal, the narrowcast receiver including an attenuator and a filter, and a controller including logic to dynamically monitor and adjust the attenuator to maintain separation between the broadcast and narrowcast signals.