Abstract: The disclosed system and method provide for a CATV power amplifier in which power dissipation may be reduced by dynamically adjusting the amplifier bias such that the bias is high only when high peak output signals need to be produced. By combining a bias control signal and an RF data signal into a single signal produced by a single DA converter, the disclosed examples require fewer DA converters and a need to synchronize DA converters to produce each of the signals individually is eliminated. A low frequency signal may be added to the RF band to find an optimum compromise between positive and negative peak excursions produced by the amplifier such that an overall reduction in bias may be achieved.

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: Techniques for transmitting an optical signal through optical fiber with an improved stimulated Brillouin scattering (SBS) suppression and an improved transmitter's signal to noise ratio (SNR) include externally modulating a light beam emitted from a light source with a high frequency signal. The light beam is also modulated externally with an RF information-carrying signal. The high frequency signal is at least twice a highest frequency of the RF signal. The high frequency signal modulating the light source can be split, providing a portion of the split signal to a phase and gain control circuit for adjusting a phase/gain. The output of phase and gain control circuit can be applied to the external modulator to eliminate intensity modulation for SBS suppression improvement. The optical transmitter's SNR is further improved by cancelling a beat between SBS suppression modulation tone and out of band distortion spectrum of information bearing RF signal.

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: Powering an active/splitter and providing information to ONUs to cause adjustments to ONU operating wavelengths. An ONU may identify the port of a splitter to which the ONU is connected in order to make wavelength adjustments. Various techniques enable the ONU to identify from which port the ONU is receiving signals, such as a splitter that splits signals to ONUs in a cable network and signals to one or more ONUs the port to which it is connected. The splitter may lack electrical power and may perform the signal function by harvesting optical power from optical power provided to the splitter. In this manner, an active splitter may behave passively with respect to powering components in the absence of electrical power.

Abstract: Particular embodiments provide a method for delivering data in the upstream direction without the need for upstream radio frequency (RF) modulation. For example, in some embodiments, an optical network may reach to a gateway associated with a user device. The gateway may receive digital baseband data from the user device in the upstream direction. The gateway can then send the digital baseband data through the optical network without modulating the digital baseband signal via radio frequency. At the headend, because no modulation is performed in the upstream direction, there is no need for de-modulation in the headend. In one embodiment, a scheduler-based approach is used to avoid instances of optical beat interference in the upstream direction as only one upstream device that may interfere with other devices may be able to send data at one time.

Abstract: An optical combiner for a communications network transmitting both upstream signals and a downstream optical signal. The communications network includes an array of amplifiers, each receiving a respective instance of the downstream optical signal. The output of each amplifier is split among a plurality of ports in a first splitter/combiner unit. The first splitter/combiner unit transmits the amplified downstream optical signal to respective second splitter/combiner units.

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: Systems and methods for amplifying signals. In some embodiments, the signals may be amplified using a diode steering network with an amplifier operated in class AB mode. In some embodiments, distortion in the amplified signal may be corrected using a feed forward cancellation circuit operated in class A mode.

Abstract: Systems and Methods for reducing distortion due to bursts of upstream transmission in an HFC CATV network. In some preferred systems, the functionality of an Optical Network Unit (ONU) may occur within a node or amplifier along a direction upstream from a subscriber's home.

Abstract: Platelets or blood cells are detected in a fluid sample by adjusting a focal depth of a microscope through a range of values, the microscope having a mounted sample and an objective lens adapted with one or both of (a) a spherical aberration correction unmatched to a utilized cover plate for the sample, or (2) a numerical aperture unmatched to a utilized illumination source for the sample. Images are recorded at different specific focal depths and in multiple z planes of a fluid bearing the platelets, where the position of platelets may overlap on different of the multiple z planes that are recorded, the images recorded through the cover plate, thus causing the generation of a specific light-dark pattern indicative of platelets at particular positions and at multiple depths in the fluid media. The images are analyzed for the specific light-dark pattern.

Abstract: Techniques for transmitting an optical signal through optical fiber with an improved stimulated Brillouin scattering (SBS) suppression and an improved transmitter's signal to noise ratio (SNR) include externally modulating a light beam emitted from a light source with a high frequency signal. The light beam is also modulated externally with an RF information-carrying signal. The high frequency signal is at least twice a highest frequency of the RF signal. The high frequency signal modulating the light source can be split, providing a portion of the split signal to a phase and gain control circuit for adjusting a phase/gain. The output of phase and gain control circuit can be applied to the external modulator to eliminate intensity modulation for SBS suppression improvement. The optical transmitter's SNR is further improved by cancelling a beat between SBS suppression modulation tone and out of band distortion spectrum of information bearing RF signal.

Abstract: An optical combiner for a communications network transmitting both upstream signals and a downstream optical signal. The communications network includes an array of amplifiers, each receiving a respective instance of the downstream optical signal. The output of each amplifier is split among a plurality of ports in a first splitter/combiner unit. The first splitter/combiner unit transmits the amplified downstream optical signal to respective second splitter/combiner units.

Abstract: A system for communicating data signals over an optical transmission path combines forward signals onto a fiber that also carriers return signals. The system includes a return receiver for detecting an optical beat interference (OBI) event. Return signals are received by return receivers, one for each group of users. The fiber is provided to a splitter that distributes the forward optical receivers to the end users (RTx), which each comprise a receiver for the forward wavelength and a transmitter for the return wavelength. The transmitters provide return signals. When multiple transmitters are on at the same time, OBI events can take place when transmitter wavelengths coincide. When the return receiver detects an OBI event, it may signal the end user devices via a forward communication. The end user devices are responsive to the OBI detection signal to adjust a return wavelength to reduce or eliminate OBI.

Abstract: An active receiver structure that combines a large number of detectors without bandwidth penalty may provide a better signal-to-noise ratio (SNR) than conventional Radio Frequency over Glass (RFoG) networks. A transmission line receiver is used to combine a large number of optical detectors into a single radio frequency (RF) signal without a bandwidth penalty and a modest penalty in noise performance that results in an SNR that is much better than traditional optical combining techniques that are followed by a single detector. An optical multiplexer structure may be designed around the active splitter such that passive optical network (PON) operation is not impeded.

Abstract: Systems and methods for achieving full duplex bidirectional transmission across coaxial cable in a hybrid fiber-coaxial cable TV network. Some preferred systems and method will attenuate reflections propagated within the coaxial cable. Other preferred systems may echo-cancel reflections propagated within the coaxial cable.

Abstract: Systems and methods for achieving full duplex bidirectional transmission across coaxial cable in a hybrid fiber-coaxial cable TV network. Some preferred systems and method will attenuate reflections propagated within the coaxial cable. Other preferred systems may echo-cancel reflections propagated within the coaxial cable.

Abstract: A smart receiver and smart transmitter for CATV networks where distortion is minimized using a spectrum analyzer.

Abstract: Systems and methods for optical modulation index calibration in a CATV network.

Abstract: In an optical system having multiple cascaded splitter/combiners, a trunk port and/or a drop port is configured for at least one of the splitter/combiner units. Drop ports may be configured with an average gain control, and the trunk ports may be configured to have individual gain control to provide a more precise overall gain and to maintain adequate signal levels. Embodiments apply to evolving RFoG architectures designed to serve a large number of subscribers without suffering from OBI (Optical Beat Interference) by retransmitting an optical signal through cascading splitters/combiners.