Abstract: Systems and methods of upstream communications using frequency modulation are disclosed. An exemplary method embodiment, among others, includes frequency modulating a communications signal, intensity modulating the frequency modulated signal, and applying that intensity modulated signal to a transmission medium. Also disclosed is a method of receiving the upstream signal including intensity demodulating the signal received from the transmission medium and frequency demodulating the resultant signal.

Abstract: The present invention is directed towards monitoring and adjusting a power level of reverse subcarrier signals at an input of an optical node as opposed to at an input of a CMTS blade. Advantageously, reverse subcarrier signals are digitally transmitted throughout the optical link thereby avoiding the use of attenuators in the optical link. Therefore, any attenuation of the power level of the reverse subcarrier signals is caused by an RF feeder portion of the communications system. The CMTS blade then detects the power level of the reverse subcarrier signal that is equivalent to the power level at the input of an optical node and sends a control signal to CPE adjusting the transmitter power level without affecting the optical node dynamic range.

Abstract: The present invention provides an apparatus and method for detecting the presence of a carrier signal that is included in the reverse signals of a communications system. The present invention uses an improved apparatus that determines the average power of the reverse signals during a predetermined counting cycle. The average power is then compared to a threshold power value. If the average power exceeds the threshold power value, an enable signal is provided to allow further transmission of the reverse signals.

Abstract: The present invention provides an improved apparatus and method for detecting a reverse carrier signal. The present invention utilizes a peak detector/envelope filter for determining the peak level of the reverse analog waveform. The peak level is compared to a threshold level during a predetermined time period to determine the presence of a valid reverse carrier signal. Once determined, an enable signal is provided to an electronics device that allows further transmission of the reverse signals.

Abstract: The present invention provides an apparatus and method for reducing the amount of ingress noise that is present in the reverse path of a two-way communication network. The present invention employs intelligent dynamic switches (200) that determine whether desirable reverse signals are present at that point in the network. If so, the reverse signals, which also probably include some amount of ingress noise, are allowed to pass further upstream. If no desirable reverse signals are present at that point in the network, the IDS (200) blocks the transmission of any reverse signal further upstream, thereby blocking the transmission of any ingress signals. Although ingress noise is allowed to travel upstream with desirable reverse signals, the performance of the overall network is improved because ingress signals are blocked at various points in the network, thereby reducing the total amount of cumulative ingress noise signals that would otherwise be present in the network.

Abstract: An architecture for providing high-speed access over frequency-division multiplexed (FDM) channels allows transmission of ethernet frames and/or other data across a cable transmission network or other form of FDM transport. The architecture involves downstream and upstream FDM multiplexing techniques to allow contemporaneous, parallel communications across a plurality of frequency channels. Also, the modulation indices of various upstream frequency channels may be different, but a plurality of upstream channels may be used to carry a single data flow generally in parallel. The upstream data flow is fragmented into blocks and formed into superframes to allow transmission over at least one upstream frequency channel. When a plurality of upstream frequency channels are utilized, the superframes facilitate the possibility of having different modulation indices on the plurality of frequency channels.

Abstract: The present invention is directed towards an open-loop thermal compensation circuit that is suitable for use in a burst-mode laser transmitter. The compensation circuit adjusts the optical power level to ensure that the laser diode remains at an optimum power level. The thermal compensation circuit includes a thermistor having a thermal current, which is dependent upon any temperature fluctuations, where the thermal current adjusts a laser current. A change in the laser current subsequently adjusts the optical power level. Also included is a control circuit for turning on and off the laser diode with a control current, which is dependent upon the presence or absence of incoming electrical signals.

Abstract: The present invention describes a method for transmitting reverse analog signals within a specific portion of a reverse band in an HFC communications system. Subscriber equipment (305) receives input defining the specific portion of the band for transmitting reverse analog signals. An optical transmitter (315) then converts the received reverse signals to digital reverse signals and transmits the digital reverse signals at a specified clock rate. Due to shifting of the digital reverse signals within the reverse bandwidth, shifting of the received digital signals reflect the specific bandwidth within which the reverse signals were originally transmitted.

Abstract: A transmitter (305) for transmitting reverse optical signals in a broadband communications system (300) that includes a converter (320) for digitizing the analog RF signals and a carrier-detect circuit (330) coupled to the converter (320) for detecting when digital RF signals are present at the output of the converter (320). When the carrier-detect circuit (330) detects digital RF signals, the carrier-detect circuit (330) allows the digital RF signals to be transmitted upstream through the broadband communications system (300). A digital network (310) then combines the received digital RF signals with other digital RF signals from additional transmitters (305). The combined digital signals are then provided to a receiver (315) that includes a converter (335) for returning the digital RF signals to analog RF signals and then providing the analog signals to a headend for further processing.

Abstract: A burst-mode optical transmitter (405) for receiving reverse electrical signals and for providing a reverse optical signal in a communications network. The optical transmitter includes a carrier-detect circuit (510) for detecting the presence of reverse electrical signals and a laser (535) for converting the reverse electrical signals into reverse optical signals for further transmission. The carrier-detect circuit (510) controls a switch (515), whereby when the carrier-detect circuit (510) detects the presence of reverse electrical signals, the carrier-detect circuit (510) closes the switch (515) activating the laser (535). When a reverse electrical signal is present, the carrier-detect circuit (510) opens the switch (515), deactivating the laser (535). In this manner, the burst-mode optical transmitter (405) only transmits reverse optical signals when reverse electrical signals are present.

Abstract: An optical commutator (310) for combining optical signals emanating from a plurality of optical transmitters (305a-n). The commutator (310) includes a plurality of input ports connected to each optical transmitter (305a-n) via an optical fiber (315a-n). The optical transmitters transmits the optical signals within a predetermined bandwidth. A switching means (410) sequentially connects each of the plurality of input ports to an output port (415), where each of the plurality of inputs ports is connected to the output port (415) at a frequency greater than twice the predetermined bandwidth. The output port (415) then provides a combined optical signal that includes the plurality of optical signals.

Abstract: A cable television interdiction apparatus comprises a microprocessor actuation and control means for actuating and controlling one or more frequency agile voltage controlled oscillators. The voltage controlled oscillators selectively jam only unauthorized premium programming transmitted from a headend to a particular subscriber. The method of interdiction comprises the steps of generating and storing voltage control words for operating the oscillators consistent with a headend selected jamming factor for a particular channel to be jammed and addressably transmitted and stored premium programming authorization data.

Abstract: An off-premises method and apparatus for the interdiction of unauthorized channels of a broadband cable television signal includes common circuitry for adjusting the amplitude and equalization levels of the broadband CATV signals and one or more subscriber modules for generating jamming signals of different frequencies which are used to interdict one or more unauthorized channels. Each subscriber module is associated with a subscriber and is programmable and addressable to adjust the jamming parameters of that subscriber independently of other subscribers. Each subscriber module circuit comprises a plurality of latches, each of which is associated with one of a plurality of digital to analog converters. Each of the digital to analog converters drives one or more frequency agile oscillators with its analog output to generate the jamming signals.

Abstract: A program control system for controlling access to premium programming and/or premium channels comprises a program control apparatus which may incorporate one or more subscriber modules. The subscriber modules may use one or more different types of program control technologies to provide different subscribers with different levels of access as well as different levels of security. One subscriber module may comprise a program control apparatus for interdicting premium programming signals transmitted "in the clear". Other modules may comprise positive or negative traps or bandstop filters. The program control apparatus allows a cable television provider to apply new or different program control technologies on a subscriber by subscriber basis.

Abstract: Networks which remove the jamming signal from the television signal supplied to subscribers for a premium T.V. channel in a cable (CATV) or other subscription television system utilizes surface accoustic wave (SAW) devices arranged to provide a broadband all pass response across the entire band covered by all of the transmitted television channels except for a notch at the frequency of the jamming signal. The narrow band response of the filter in the premium channel is such that the notch presents insertion loss at the jamming signal frequency and over a frequency range to accommodate shifts in the frequency response of the SAW devices with respect to the frequency of jamming signal, which insertion loss is about 100 times the insertion loss at the picture carrier frequency of the television signal, even though the picture carrier and the jamming signal frequency may be within about 200 KHz apart from each other.