Abstract: A method is described for compressing and/or transporting and/or decompressing a digital signal. The most significant bits of a sample of the digital signal are compressed and transported as a compressed transport sample. Methods are used to improve the compression and transport as hybrid DPCM and a dynamic shift of clip range of prediction errors. For every sample, not only a compressed transport sample but also a residual transport sample is transmitted. The residual transport sample is either equal to the least significant bits of the sample or equal to a substitution value which is a function of the clipping error from the compression of the most significant bits of the said sample. Apparatuses are described for compression and/or transport and/or decompression of a digitized television IF signal according to the method.

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, connects 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. 6) 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: The present invention is directed towards a cache management system for a set top box that improves the loading speed of hypertext markup language (HTML) documents that are provided by web servers. The cache management system includes a set top box with a processor and memory that includes cache, where a plurality of HTML documents is stored in the cache. A cache manager manages the cache and calculates a removal factor for each of the HTML documents. The cache manager removes at least one of the HTML documents based on its removal factor until sufficient room is available for an additional HTML document. Additionally, the cache manager keeps the maximum number of relevant web pages in cache to maximize loading speed.

Abstract: The present invention is a navigational user interface for interactive television. The invention uses an intuitive interactive interface for navigating through service options preferably offered by a cable television service. Services offered such as video on demand, purchasing delivery foods, restaurant selection, banking and community events is all navigated using the present invention.

Abstract: A fiber-to-the-home (FTTH) system transmits forward and reverse optical signals, such as video, voice, and data signals, via optical fiber, and includes a plurality of home network units. The home network units include an FTTH optical receiver for receiving at least one of the video, voice, and data signals. A triplexer distinguishes and separates the video, voice, and data signals, wherein the video signals have a first wavelength and the voice and data signals have a second wavelength. The voice and data signals are provided to the home network unit for further processing. The triplexer provides an electrical signal to the amplifier stages. The amplifier stages include a preamplifier stage and a postamplifier stage. A gain control circuit automatically adjusts the gain of the video signal based upon the input power level to the FTTH optical receiver. Additionally, a tilt network performs level compensation for externally located coaxial cable.

Abstract: A method and system that provides a single multipurpose PPV channel that a subscriber tunes for all PPV services. From the subscriber's perspective, the program guide, previews, advertising, purchasing options, and showings of all PPV events occur on a single channel. There can be a single multipurpose PPV channel for all PPV services or single PPV channels for groups of similar services, such as a single Family PPV channel, a single Sports PPV channel, and a single Adult PPV channel that each represent single multipurpose channels for similar programming. The advertising on a single multipurpose channel can be directed to the type of programming on all the channels in the group. Once a subscriber purchases a PPV event, the HCT tunes to the MPEG transport stream and program information for the selected PPV event and displays the PPV event on the single multipurpose PPV channel at its associated start time. The subscriber does not have to select another channel.

Abstract: A transmitter (501) for use in a communication system (500) includes clock input for receiving a clock signal and input ports (503, 510, 513) coupled to external signal sources for receiving input signals that are synchronously modulated at modulation frequencies rationally and fractionally related to the clock frequency and to each other. Additionally, the clock frequency should be greater than any of the modulation frequencies. An analog-to-digital converter (505) receives the analog input signals and converts them to a digital format, and a multiplexer (515) then processes the digital input signals and signals from the converter (505) to generate a single serial output signal. An output port of the transmitter (501) then transmits the single serial output signal as a digital signal having a bit rate equivalent to the number of input signals multiplied by the sampling frequency, plus additional overhead for optional framing and error correction.

Abstract: A power supply system that provides redundant power by automatically selecting one power supply as the master power supply. Power supplies configured in parallel share load. The load voltage of the power supply is compared to a reference voltage producing output errors. The error is amplified and compared with the peak switch currents to determine the pulse width of the power supply switch. The power supply with the highest error voltage controls a shared bus and thus become the master. The remaining power supply (or power supplies) having a lower error voltage becomes (or became) the slave power supply. Thus, the system automatically provides redundancy with one power supply operating as the master and the remaining ones as the slave power supplies. Due to the common shared bus, all the paralleled power supplies have the same peak currents through their switch and to the load.

Abstract: A method and system for designating and identifying individual programming that is available in a subscriber television system as a pay-per-view event. The identified programming includes programs that are not normally available for viewing by some subscribers or for which a subscriber has not subscribed. The programming can include an individual program, groups of programs, and non-pay-per-view channels. The subscriber can then elect to view the programming as a pay-per-view event.

Abstract: The preferred embodiment of the present invention varies the speed of processor execution, including associating a clock rate with each thread in a plurality of threads and executing each thread in the plurality of threads on the processor at the clock rate associated with the thread.

Abstract: A cable converter box is a capable of receiving a cable signal that includes both NTSC and digital television (DTV) formatted signals. When the converter box is tuned to a channel, the converter box determines whether the channel carries an NTSC or DTV signal. If the signal is NTSC, the signal passes through an up/down converter, is demodulated in a conventional manner, and is remodulated in order to be provided to the TV on a pre-selected channel. If the signal is DTV, the signal passes through the up/down converter, but not through the demodulator, prior to being output to a DTV-compatible TV on the same pre-selected channel as the NTSC signal. This prevents the user from having to change the tuner on the TV when the cable converter is changed to a DTV channel.

Abstract: A digital signal processing vestigial-sideband television modulator receives a television signal. The present invention digitizes the television signal to generate a video signal and a digital processor processes the video signal to generate a complex baseband signal. The complex baseband signal is converted into an in-phase baseband signal and a quadrature baseband signal and modulated to respectively generate a modulated in-phase baseband signal and a modulated quadrature baseband signal. The modulated in-phase baseband signal and the modulated quadrature baseband signal are combined to produce a vestigial radio frequency television signal. The undesired sideband of the vestigial radio frequency television signal is tapped, filtered, and, subsequently, the power level of the undesired sideband is detected. Any imbalance in the modulation process is compensated by using the detected power level of the undesired sideband.

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 modem, 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: 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. A digital flywheel provides continuous feedback from an encoding system to a video compression engine in order to assure that the clock rates between the two remain appropriately synchronized.

Abstract: The preferred embodiment describes a thermal controller (305) that provides protection for heat sensitive devices (310) within an amplifier module (315). A thermal sensing circuit (370) is used for detecting any increases in temperature surrounding the devices (310) and the output is provided to the thermal controller (305), wherein the thermal controller (305) provides a current-limiting control (445), a voltage control (440), and a status monitor control (450).

Abstract: The preferred embodiment describes a regulating device (400) that regulates current flow through a thermoelectric cooler (TEC) (420) with higher power efficiency than conventional regulating methods. The regulating device includes a voltage controller (415) that receives an input voltage from a comparator (435) that has determined whether there has been a change in temperature surrounding a temperature sensitive device, such as a laser, by way of a thermistor (425). The controller (415) then controls two pulse width modulated (PWM) synchronous rectifiers (405, 410). The combination of the controller (415) and the synchronous rectifiers (405, 410) improves the power efficiency of the regulating device (400). Each PWM synchronous rectifier (405, 410) includes two field effect transistors (FETs) that supply substantially a constant current flow through the TEC (420) to either heat or cool a control surface (430).

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 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.