Abstract: An embodiment includes an input node, a shunt impedance electrically connected to the input node, and at least one shunt diode connected in series with the shunt impedance. The input node receives an electrical signal from a signal generator. A bias current is applied to the shunt diode from a bias supply. In response, the shunt diode generates second-order distortion and substantially no third-order distortion. The level of bias current is adjusted to substantially eliminate any third-order distortion while the shunt impedance is adjusted so that the appropriate amount of second-order distortion is generated as predistortion. The predistortion is then provided to a nonlinear device, such as a laser, where it operates to substantially cancel inherent distortion generated by the nonlinear device.

Abstract: A removable plug-in board for dividing incoming radio frequency (RF) to an external port and providing alternating current (AC) signals to a CATV system amplifier contains a radio frequency choke or inductor for passing the AC power signal, a high pass filter for passing the radio frequency signal and either a directional coupler or a splitter. This plug-in board is inserted into a motherboard on which is mounted amplification circuitry and power supply and divider circuitry. The plug-in board routes RF signals arriving on an input port of the amplifier motherboard through the directional coupler to the amplification circuitry, while additionally tapping off and feeding the incoming RF signals to a second output port of the amplifier motherboard.

Abstract: A communication system (100) processes forward signals generated by headend equipment (105) and reverse signals generated by subscriber equipment (135). A communication medium (110, 120), such as fiber optic cable or coaxial cable, couples the headend equipment (105) and the subscriber equipment (135), and amplifiers (400) are positioned at various locations along the medium (110, 120) to amplify the forward and reverse signals. The amplifiers (400) include a dual forward/reverse test circuit (FIG. 5) having a forward test point (406) coupled to the forward signal, a reverse test point (408) coupled to the reverse signal, and a single directional coupler (404) connected to the forward test point (406), for providing the forward signal thereto, and to the reverse test point (408), for providing the reverse signal thereto.

Abstract: An interactive terminal comprises a processor, a local data store connected to the processor, a character generator responsive to processor control for generating a television signal output to an associated television receiver, a key pad or remote control for inputting information to the processor, and a power supply input. The terminal is coupled, via 2-way RF communications, to a central location, designated as the system manager, where the terminal is accessed by polling for monitoring and servicing terminal user requests. The interactive terminal has a local storage capacity for storing a number of character screen commands, accessed from a central data base at the system manager, for use in generating prompting screens displayed on the television receiver. In use, a user may call for a variety of services by operating the input keys of the key pad to cause a prompting screen to be displayed. Screen commands are stored at the terminal according to an assigned priority.

Abstract: A highly stable soliton source uses a bulk Er/Yb glass laser which operates in two longitudinal modes of the laser cavity with substantially identical amplitudes to generate beat modulation. The beat modulation is then passed through a pulse compression fiber which compresses the beat modulation into a train of soliton pulses. Because the beat modulation is between two modes of the same laser cavity, the soliton pulse train generated is highly stable with low timing jitter.

Abstract: An optical transmitter (405) includes a distributed feedback semiconductor laser (100) operated in a linear regime below a threshold associated with stimulated Brillouin scattering to generate an optical signal. A resistor (125) or other heater is physically coupled to the semiconductor laser (100), and a modulated current source (120) drives the resistor (125) with a triangle waveform (300), thereby varying an optical wavelength of the optical signal such that the optical signal and a double Rayleigh backscattered signal are characterized, at the optical receiver (410), by different optical frequencies. As a result, interference generated by Rayleigh backscattering is minimized at the optical receiver (410).

Abstract: The problem of wasting IP addresses by statically assigning them to hosts is solved as follows: when a cable router or RF modem becomes active, it sends a message requesting a set of IP addresses from the head end, which dynamically assigns the set of IP addresses and sends a message comprising the set of IP addresses to the cable router or RF modem. The cable router or RF modem then responds to requests by the hosts for IP addresses by assigning them IP addresses from the set. Furthermore, the set of IP addresses is released when the session terminates with the cable router or RF modem.

Abstract: A display system for providing programmable on-screen displays for a subscriber terminal, includes a control processor and a display processor which generates such displays from stored display information and display attributes. The control processor executes display routines to configure the display processor and to load the display data into a display memory. The display routines, display attributes and display data are programmable and can be varied for optimal use of the display processor. In one implementation, such information can be modified by changing the programming in non-volatile memory of the subscriber terminal, either by switching ROM or Flash EPROM ICs or by a plug in module. Another implementation includes downloading the information with other executable code and data in the read/write portions of the non-volatile memory.

Abstract: A communications system includes first and second fiber optic links, each including at least one fiber optic cable, and a coaxial distribution plant including coaxial distribution lines and a plurality of amplifiers. A first fiber optic node couples the first fiber optic link to the coaxial distribution plant and a second fiber optic node located proximate to one of the amplifiers of the coaxial distribution plant couples the second fiber optic link to the coaxial distribution plant.

Abstract: A method and apparatus for providing command and control of remote systems using low earth orbit satellite communications is disclosed. According to the present invention, a programmable transceiver apparatus provides a two-way communications path between a remote user and a control center via a low earth orbit satellite at frequencies below 1 GHz. The transceiver apparatus includes a transceiver for communicating with the low earth orbit satellite; an antenna coupled to the transceiver; at least one interface communicating signals between at least one external device located at the remote user, wherein the transceiver apparatus is programmed to transmit data related to the external device to the satellite in response to a signal communicated to the transceiver via the low earth orbit satellite, an internal program of the transceiver or an alarm or exception signal generated by any of the external devices or the user.

Abstract: A cable television system provides conditional access to services. The cable television system includes a headend from which service "instances", or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Abstract: A holder (200) for holding an electronic component (100), which can be inserted into and removed from the holder (200), is formed to be both electrically and thermally insulative. The holder (200) is formed from an insulative body molded to form a cavity (205) into which the electronic component (100) can be inserted. The insulative body includes sidewalls (210) formed to partially enclose the electronic component (100) when it is inserted into the holder (200) and a bottom surface (250) formed perpendicularly with the sidewalls (210). The bottom surface (250) defines at least two apertures (225) through which terminals (110) of the electronic component (100) can extend.

Abstract: A reconfigurable connectorization panel assembly for a circuit board housing rack or chassis, particularly suitable for use in cable television (CATV) headend equipment. Each circuit module for use in the rack has an associated rear panel assembly or "connectorization panel" that bolts onto the rear side of a chassis which supports the rack and a backplane. The connectorization panels extend plug-action connectors through openings in the rear panel of the chassis and in the backplane, and mate with corresponding connectors on the circuit modules. On the rear side, the connectorization panels provide appropriate drop side connectors required for input/output signal cabling. The connectorization panel adapts a particular slot in the chassis for a particular type of input/out cabling and connectors. The slot can be reconfigured for a different type of circuit module by affixing a different type of connectorization panel.

Abstract: A tap (125) for use in a cable television system (100) includes an incoming port (202) for receiving an incoming signal from a head end section (105) and at least first and second outgoing subscriber ports (225, 230) for transmitting outgoing signals to system subscribers. The first and second subscriber ports (225, 230) can be enabled or disabled, depending upon whether cable service is to be provided from a particular port. The tap (125) also includes light sources (250, 260) located on the body of the tap (125) to indicate statuses, i.e., enabled or disabled, of the subscriber ports (225, 230).

Abstract: A chassis (200) having cable management features includes a frame (210) for holding communication modules (105) that have cables (305) coupled to front surfaces thereof. The chassis also includes cable tunnels (225) formed beneath the frame (210). The cable tunnels (225) are each defined by sidewalls and upper and lower surfaces that form an aperture through the tunnel (225), and the module cables (305) from a particular module (105) can be routed through its associated cable tunnel (225) beneath the frame (210). The chassis (200) also includes cable guides (230), each defining an opening associated with a particular communication module (105), wherein cables (305) coupled to that communication module (105) can be routed through its associated cable tunnel (225) and then through its associated cable guide (230).

Abstract: The laser device of the present invention includes a high-power, fiber-coupled optical source (FIG. 1) having a broad area laser diode (10) with a high reflective coating at its rear facet (12), coupling optics (20), and an optical fiber (30) having fiber grating (32). The fiber grating (32) serves to reflect a portion of the optical beam back to the broad area laser diode (10), thereby stabilizing the wavelength of the optical beam. The fiber grating (32) and the rear facet (12) of the broad area laser diode (10) serve as nodes for an external resonator, thereby limiting the diffraction of the optical beam. The effects of wavelength fluctuation and beam diffraction are reduced together using minimal mechanical components.

Abstract: A cable television system (100) includes a head end section (105) for generating a cable signal; a communication medium (110, 117), such as fiber optic cable and coaxial cable, coupled to the head end section (105) for routing the cable signal through the cable television system (100), and cable taps (200) coupled to the communication medium (110, 117) for receiving the cable signal and providing subscriber drops to subscribers of the cable television system (100). As the cable signal is routed through the system (100), the signal levels of the signal decrease, and higher frequencies are attenuated more rapidly than are lower frequencies of the signal. Therefore, taps (200) of the cable television system (100) include equalizer circuits (212) for attenuating lower frequencies of the cable signal to provide relatively flat signal levels at the subscriber drops.

Abstract: A terminal apparatus for use in a cable television system which provides a plurality of channels capable of being tuned for display at a television receiver is provided. The apparatus includes a memory for storing data for generating a plurality of predetermined character screens and for storing deauthorization data, a character generator for generating character screens from the stored character screen data at the television receiver, a deauthorization mechanism responsive to the deauthorization data in the memory for deauthoring selected ones of the plurality of channels, and a controller for controlling the memory and the character generator, and for composing at least one predetermined character screen for display at the television receiver in accordance with the deauthorization of a channel by the deauthorization mechanism.