Abstract: Techniques for determining an output rate for a bit stream, the output rate being determined by applying information read from the bit stream to a model of a receiver for the bit stream. The techniques are employed to construct a statistical multiplexer that multiplexes varying bit-rate MPEG-2 bit streams onto a satellite up-link. Minimum and maximum output rates for each MPEG-2 bit stream are determined such that neither a queue for the bit stream in the multiplexer nor the bit stream's decoder will underflow or overflow. The rates with regard to the decoder are determined using timing information read from the bit stream and a general model of an MPEG-2 decoder. The multiplexer first allocates each bit stream its minimum bandwidth and then allocates any remaining bandwidth to the bit streams in proportion to the difference between the minimum and maximum output rates for the bit streams, with no bit stream receiving more than its maximum output rate.

Abstract: An electrical connector (305) with a conductive contact (420) that self-aligns via formed notches (425). The contact (420) also includes an opening (503) formed in a central region thereof for mating with a snap protrusion within an insulator (415) and flexibly holding it in place allowing the contact (420) to float within the insulator (415). The connector (305) additionally includes a plug that is inserted and retained into an aperture formed in the insulator (415). The connector (305) is rotated and electrically couples the contact (420) with the conductive member (310), thereby allowing alternating current (AC) power to flow through the connector (305).

Abstract: A cable television system (400) includes a transmitter (200) for generating a digital optical signal and a receiver (201) for receiving such digital optical signal and converting it to an analog signal. The receiver (201) includes a digital filter (300) disposed between a deserializer (225) and a digital-to-analog converter (230), which digital filter conditions the digital electrical signal received from the deserializer (225). 1o The digital filter (300) is employed as a digital noise mitigation block so as to improve the quality of the signals in the reverse path, returning to the cable television system (400) headend (105).

Abstract: A control system provides secure transmission of programs, including at least one of video, audio, and data, between a service provider and a customer's set top unit over a digital network. Program bearing data packets are received in a first network protocol over a first data link and removed from the first network protocol. Packets representing a particular program requested by a customer having a set top unit are selected. Conditional access is provided to the selected program. In particular, program bearing packets are encrypted according to a first encryption algorithm using a first key, which is then encrypted according to a second encryption algorithm using a second key. The first keys are transported in packets to the customer's set top units along with the program packets. A public key cryptographic technique encrypts the second key such that the public key used in the encryption corresponds to the private key of the customer's set top unit.

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 plastic housing for enclosing electronic circuitry that includes connectors for receiving and transmitting RF signals and power. The connectors include a center conductor and a shield, whereby a conductive liner within the plastic housing is connected to the shield of each connector. The conductive liner is capable of passing a minimum of 15 amperes of current through ground and also shields the enclosed electronic circuitry from EMI and RFI. Additionally, the plastic housing is capable of withstanding a significant amount of heat that is internally generated by the enclosed electronic circuitry.

Abstract: A broadband communication system (60), such as a cable television system, includes a forward path for transmitting information from headend equipment to subscribers and a reverse path for transmitting information from the subscribers to the headend equipment. The reverse path includes a transmitting station (65) that receives a first analog signal, converts the first analog signal to a first digital signal having a first number of bits, encodes the first digital signal to generate a second digital signal having a second number of bits less than the first number of bits, then optically transmits the second digital signal. A receiving station (70), also located in the reverse path, receives the second digital signal, decodes the second digital signal to generate a third digital signal having a third number of bits greater than the second number of bits, then converts the third digital signal to a second analog signal that approximates the first analog signal.

Abstract: Techniques for determining an output rate for a bit stream, the output rate being determined by applying information read from the bit stream to available bandwidths. The techniques are employed to construct a statistical multiplexer that multiplexes varying bit-rate bit streams onto a satellite up-link. Minimum and maximum output rates for each bit stream are determined such that neither a queue for the bit stream in the multiplexer nor the bit stream's decoder will underflow or overflow. The multiplexer looks at the fullness of the memory buffers and correlates the fullness with the likelihood of a condition in which output will exceed bandwidth. If there is not enough bandwidth to give every bit stream its minimum rate, glue frames may be inserted, or low priority channels dropped.

Abstract: Systems and methods for digitizing broadband signals using multiple analog-to-digital converters (ADCs) and a calibration system for adjusting the phase and bias of the sampled signal such that the output digitized, sample closely approximates the input broadband analog signal. A calibration signal is combined with the broadband signal and the combined signal is converted to digital. The combined signal splits into portions equal to the number of ADCs in the system. An off-line digital signal processor (DSP) analyzes samples representing a portion of the combined signal and computes any necessary adjustments to phase and amplitude of the digitized samples. If adjustments are required, a real-time DSP adjusts the phase and amplitude of the digitized sample, by use of a multiplier and/or adder included in the real-time DSP. The separate portions of the digitized sample are recombined by a multiplexer to create a single digitized output representing the broadband analog signal.

Abstract: Techniques for determining an output rate for a bit stream, the output rate being determined by applying information read from the bit stream to available bandwidths. The techniques are employed to construct a statistical multiplexer 80 that multiplexes varying bit-rate bit streams. Minimum and maximum output rates for each bit stream are determined such that neither a queue for the bit stream in the multiplexer nor the bit stream's decoder will underflow or overflow. The multiplexer first allocates each bit stream its minimum bandwidth and then allocates any remaining bandwidth to the bit streams in proportion to the difference between the minimum and maximum output rates for the bit streams, with no bit stream receiving more than its maximum output rate. If there is not enough bandwidth to give every bit stream its minimum rate, glue frames may be inserted, or low priority channels dropped.

Abstract: An optical fiber (10) made with a central core (12), a first cladding layer (16), and a second cladding layer (18) having a series of perturbations or irregularities formed into the otherwise generally circular outer boundary of the first cladding layer (16). The irregularities in the first cladding layer (16) interrupt the propagation of skew rays and encourage coupling into the core (12).

Abstract: An asymmetrical network for coupling customer-premises Internet hosts such as personal computers to the Internet. The head end of a CATV system has a high-bandwidth connection to the Internet. The down link connecting the personal computers to the Internet is the cables provided by the CATV system; the up link is a telephone connection to the head end. A router is connected to the down link by means of an RF modem, to the up link by means of an analog modern, and to a LAN which is connected to the Pcs. The router routes IP packets for the hosts that are received on the CATV cable to the hosts via the LAN; it routes IP packets from the hosts that are destined for the Internet to the head end via the telephone line. The asymmetrical network conserves IP addresses and addresses on the CATV cable by dynamically allocating the IP addresses for an RF modem's hosts and an address on the CATV cable for the RF modem in response to a request made by the RF modem via the telephone line.

Abstract: A broadcast file system organizes data sent to a client by broadcast via a high capacity data broadcast delivery network from a plurality of servers. The data is organized into a hierarchical file system including a directory index. A server registers to send data via the broadcast file system of the present invention and is assigned a respective directory. The server may create, modify, or delete a subdirectory or a file under the respective directory of that server. The directory index is periodically broadcast. The client caches this directory index and presents the directory index to a client application. The client application may request a portion of data from the directory index. The data available from the plurality of servers is periodically broadcast to the client, and the client filters out the requested portion of data to be provided to the client application.

Abstract: A computer-implemented method and apparatus for restoring operating systems within a set-top box system. The restoration provides for operating a first operating system in a first memory. An application program is operated in a second memory. The first operating system is stored in a second memory so that a second operating system is loaded into the first memory. When a predetermined condition which is associated with the second operating system is detected, the first operating system is loaded into the first memory in response to the detected predetermined condition. Such a system provides such non-limiting advantages to the set-top box as the ability to robustly recover from errors or anomalies associated with downloading an operating system.

Abstract: A cable television tap (500) for receiving a forward signal including an information signal and a power signal. The tap (500) includes a diplex filter (520) for receiving the forward signal and for separating the information signal from the power signal at outputs of the diplex filter (520) and a plurality of subscriber ports (535) coupled to an output of the diplex filter (520) for receiving the information signal such that the information signal can be accessed at each of the plurality of subscriber ports (535). The tap (500) also includes a removable port device (555) coupled to the other output of the diplex filter (520) for receiving the power signal, and the port device (555) has a connector (550) so that the power signal can be accessed. According to the present invention, when the port device (555) is coupled to the tap (500), the information signal can only be accessed at the subscriber ports (535), and the power signal can only be accessed at the connector (550) of the port device (555).

Abstract: An electronic module that includes a housing and electronics that has a divider (215) that is substantially conductive, rectangular, and planar. The divider (215) is hingeably coupled to the housing with hinges (225). The divider (215) defines an upper section (210) and a lower section (205) within the housing, wherein the divider (215), in an open position, allows access to electronics (223) within the lower section (205), and the divider (215), in a closed position, allows access to electronics (223) within the upper section (210). The divider (215), in the closed position, provides electromagnetic shielding between the electronics (223) in the upper section (210) and the electronics (223) in the lower section (205).

Abstract: The disclosed invention relates to a pick list generator which displays selectable terms for inclusion in a selection field. One embodiment of the pick list generator is in assisting an Internet user in the user's population of search fields without the use of a keyboard containing all 26 letters and 10 digits. Accordingly, through application of the present invention, browsing and searching of the Internet is enhanced for the keyboardless user.

Abstract: A cable television system (100) having forward and reverse paths includes, in the reverse path, a digital optical transmitter (200) for receiving an RF signal, converting it to a digital signal, and adding a digital pilot tone thereto. A laser is driven in accordance with the summed digital signal to generate a digital optical signal representative of the pilot tone and the RF signal. The cable television system (100) also includes an optical receiver (305)for receiving the digital optical signal and recovering therefrom the RF signal and the pilot tone. The optical transmitter (200) and receiver (305) are coupled by fiber optic communication media (110).

Abstract: A cable television system (700) includes a clock source (710) for generating a clock signal, an optical receiver (605) coupled to the clock source (710) for recovering the information in accordance with the clock signal, and an optical transmitter (800) that has input ports (720) for receiving first and second information signals and a clock port (760) for receiving the clock signal. An interleaver (745) within the transmitter (800) is coupled to the input ports (720) and to the clock port (760). The interleaver (745) interleaves bits of the information signals in accordance with the clock signal to generate a serial bit stream that is used to modulate a laser diode (750), thereby generating a digital optical signal that is transmitted to the optical receiver (605) over an optical communication medium (110).