Abstract: A method and apparatus are provided for recovering and tracking the carrier in a QAM communication system, even under heavy interference conditions. A subset of fixed points is defined on an ideal constellation pattern for comparison to the data points in a received signal. The subset includes all of the points intersected by n radii (e.g., the four diagonals) of the constellation pattern. Additional points along the perimeter of the constellation pattern can also be provided in the subset. Data points received via a carrier are correlated with the fixed points of the subset in order to generate an error signal indicative of a phase difference between the fixed points of the subset and the received data points correlated therewith.

Abstract: A video decompression processor acquires video data for a desired service from a packetized data stream. The data stream includes transport packets carrying different components of the desired service. Each component is identified by a unique packet identifier (PID). One of the components includes a program clock reference (PCR) providing timing information for the desired service. The PIDs of the transport packets are monitored to recover video packets. Header information from the recovered packets is processed to recover packetized elementary stream (PES) packets having a PES header and picture information. Time stamp information obtained from the PES header is appended to the picture information for storage in a video memory. Picture information can subsequently be read from the memory and decoded using the appended time stamp information without having to reaccess the PES header. Various schemes for detecting, masking and recovering from transmission errors are disclosed.

Abstract: The subassembly of the present invention includes three pairs of aligned steering diodes and a single thyristor situated between spaced apart conductive heat sink plates. The subassembly is configured to fit into a standard 3-lead transistor outline package by arrangement of the semiconductors and shaping of the conductive plates. In one embodiment, the plates are square, and the components are arranged such that the diode pairs and thyristor are proximate the corners of the plates. In another embodiment, a "T" arrangement is utilized for the components which are situated between "H" shaped plates.

Abstract: A method and apparatus are provided for convolutionally encoding digital data with a rate 4/5 convolutional code. A nonoptimal rate 1/2, sixteen-state convolutional code is punctured to rate 4/5 using a puncture map of ##EQU1## and octal generators 25, 37 wherein .nu.=4. An incoming data stream is processed using the rate 4/5 code. Punctured rate 3/4 and 6/7 codes are also provided.

Abstract: Apparatus is provided for securing the integrity of a functioning system. The apparatus comprises a primary device for performing a function having a first vulnerability and a secondary device having a second vulnerability which is identical to the first vulnerability of the primary device. The secondary device is adapted to secure the function performed by the primary device in response to activity breaching the second vulnerability.

Abstract: A succession of variable length data packets containing a header portion and data portion are received. Selected data from the data packet headers is stored in designated locations of a header memory. A data packet start address is provided with each stored header portion to designate a location in a data memory for commencing the storage of data contained in a corresponding data packet. The data from the received data packets is stored commencing in the data memory locations designated by the corresponding data packet start addresses. In an illustrated embodiment, the data packets are macroblocks from digitized television frames. A plurality of next data packet position indicators are provided in the data, for use in periodically verifying macroblock boundaries during the receipt of the television data and to provide a rapid recovery from a transmission error affecting the actual or identified length of a macroblock.

Abstract: A power-out reset circuit includes reference voltage and current generators to generate a reference voltage and a reference current which are essentially independent of temperature variations over a useful temperature range, a delay/disable circuit, over and under voltage detectors and output logic circuitry. This circuit detects when the voltage level of a supply voltage source (+VDD) exceeds preselected limits. The reference voltage, which is related to the silicon band gap voltage, is connected to a first input of a comparator of each of the voltage detectors. The reference current, which is derived from the silicon band gap voltage, is connected to a current source of each of the detectors. Each detector has a hysteresis circuit which changes the point at which the comparator switches in the event that +VDD crosses into or outside of a preselected operating range.

Abstract: Incremental delivery of authenticated access rights to an access control processor is provided. Subgroups of the access rights are communicated to the processor in a plurality of messages. The subgroups are stored in different data banks within the processor, and validity designations associated with the data banks indicate whether the data currently stored therein has been authenticated under a cryptographic key currently in use. Access under a particular key is limited to that provided by access rights contained in storage banks having a validity designation in a valid state for that key.

Abstract: Interface apparatus is provided for enabling a digital video recorder to function as a universal data recorder. A random input data stream provided at a first data rate is converted to a format that emulates a video signal. The converted input data is input, at a video signal data rate, to a digital video recorder for storage. The stored converted data is played back from the video recorder at the video signal data rate. The retrieved data is then converted back to the original format of the input data stream at the first data rate.

Abstract: Alignment of an antenna and a polarizer for the antenna are automatically adjusted and the frequency setting of a frequency-tunable receiver is automatically adjusted while receiving a broadcast communication signal that is forward-error-correction coded by processing the forward-error-correction code of the received signal to measure a channel-bit-error-rate-affected parameter for the received signal; by realigning the antenna and the polarizer from their respective initial positions in response to the measured parameter until the measured parameter is minimized; and by retuning the receiver from its initial frequency setting in response to the measured parameter until the measured parameter is minimized.

Abstract: A frequency allocation is provided to minimize the effects of amplifier distortion in a mixed analog and digital cable television system. In particular, successive digital channel signals having a bandwidth substantially equal to .omega. are separated by a pair of adjacent analog channel signals, each having a bandwidth substantially equal to .omega.. In an illustrated embodiment, the analog and digital channel signals comprise amplitude modulated carriers having substantially equal power levels.

Abstract: A Cable Television (CATV) Converter box or computer has a Smart Card connector mounted in a bottom wall thereof. The Converter box includes a case having a top wall, the bottom wall, and four side walls, a main printed circuit (PC) board mounted within the Converter box and parallel to the top and bottom walls thereof, and a Smart Card connector. The Smart Card connector is mounted directly onto the PC board and within a protrusion of the bottom wall of the Converter box. The Smart Card connector defines an opening which is aligned with a first end of a groove defined in the bottom wall of the case for receiving a Smart Card storing a predetermined signal security decrypting algorithm. A second end of the groove is either formed in one of the side walls of the device or in the bottom wall of the case. The Smart Card is installed by inserting the Smart Card in the groove and placing it into contact with the Smart Card connector.

Abstract: In long distance digital and frequency modulation systems that use optical sources having optical frequency chirp, degradation due to optical dispersion in the transmission fiber is overcome by filtering the laser wavelength representative of one of the binary levels (e.g., binary "0"). An optical source such as a DFB laser is directly frequency modulated by a digital data stream. A first digital level is represented by a first intensity of the modulated carrier corresponding to a carrier wavelength .lambda..sub.1 and a second digital level is represented by a second intensity of the modulated carrier corresponding to a carrier wavelength .lambda..sub.2. A wavelength selective reflector is used to filter the wavelength .lambda..sub.1 from the modulated carrier. The modulated carrier, from which wavelength .lambda..sub.1 has been filtered, is then coupled to an optical communication path for transmission.

Abstract: A diverter interfaces first and second telecommunication lines from first and second telecommunication sources, respectively, with a third line coupled to a station set. The diverter includes separate line and set monitors and a control unit. The line and set monitors monitor and detect predetermined selective signals such as (a) ringing signals propagating on the first and second lines, and (b) line access codes, flash hook, and line change requests signals generated by the station set. In response to the detected predetermined selective signals, the line and set monitors generate first, second, and third output control signals representative of the predetermined selective signals on the first, second, and third lines, respectively, to the control unit.

Abstract: Digital data is communicated using trellis coded QAM. Symbols are coded for transmission using a rate 1/2 convolutional encoder punctured to rate 2/3. The coded symbols are transmitted for receipt at a receiver. At the receiver, two sets of branch metrics are computed for each received symbol. The received symbols are decoded by using the branch metrics to effect two passes through a modified rate 1/2 Viterbi decoder for each symbol.

Abstract: A single optical source is shared by a plurality of optical communication paths to communicate different information signals on the different paths. A high power optical carrier generator provides a carrier signal to an optical multiplexer. The multiplexer splits the optical carrier into a plurality of paths, each including an external optical modulator. The external optical modulator in each path is used to modulate the carrier in its respective path by a desired information signal. An additional modulated optical carrier can be coupled to one or more of the optical communication paths for the communication of additional information such as a standard set of television channel signals in a cable television network.

Abstract: A scheme is provided for processing previous frame data in a motion compensated digital video system to interpolate pixels used in reconstructing a current video frame. Pixel data from a previous video frame is arranged into sub-blocks containing a plurality N of pixels. The sub-blocks are stored in a memory to enable the retrieval of at least one sub-block per memory access cycle. A plurality M of sub-blocks are retrieved from the memory in response to a displacement vector associated with a portion of a current video frame. M is less than or equal to N and the M sub-blocks are retrieved in no more than M memory access cycles. A subset of pixels is chosen from the selected plurality of sub-blocks for use in interpolating pixels for the current video frame portion. The subset of pixels is processed over no more than N memory access cycles to provide N interpolated pixels for the current video frame portion.

Abstract: Apparatus for generating two output signals with a selective predetermined constant phase difference therebetween from an input reference signal having a predetermined frequency and phase includes, in one embodiment, a first and a second Programmable Delay, and a first and a second Synthesizer. The input reference signal is provided as separate inputs to the first and second Programmable Delays which generate first and second output signals, respectively, with selective predetermined delay differences therebetween for transmission to the respective first and second Synthesizers. Each of first and second Synthesizers are phase locked loops with a Programmable Divider and an optional Prescaler added to the loop to divide a high frequency output signal generated by a Voltage Controlled Oscillator (VCO) to a frequency of the output signal from the associated Programmable Delay in order to correct for any phase difference between the output signal of the VCO and the input signal from the Programmable Delay.

Abstract: A double conversion frequency converter includes first and second mixing stages. The first mixing stage includes a first programable Local Oscillator (LO) synthesizer and a first mixer, and the second mixing stage includes a second programable LO synthesizer and a second mixer. The first and second LO synthesizers have a wide band tuning range for receiving a separate predetermined reference signal and generating therefrom first and second LO output signals, respectively, which each are changeable by predetermined large frequency steps. The first mixer mixes an input signal to the frequency converter with the first LO output signal for generating a first predetermined mixer output signal. The second mixer mixes a predetermined sideband generated in the first predetermined mixer output signal with the second LO output signal for generating a second predetermined mixer output signal which is use for the output signal for the frequency converter.