Abstract: A cable television system (400) includes a transmitter (200) for generating a digital optical signal (204) and a receiver (300) for receiving said digital optical signal and converting it to an analog signal. The transmitter (200) includes a processor (238) for processing inputs and generating a gain/loss parameter which is applied via a gain/loss amplifier (250) to an incoming analog signal (232). The modified digital signal received by the digital optical receiver (300) decodes the applied gain/loss parameter at a converter (325) and applies the information to the output analog signal via a gain/loss amplifier (330).

Abstract: An amplifier (125) includes at least one gain stage (210) for amplifying a signal received by the amplifier (125). The amplifier (125) also includes an AGC circuit (400, 500) that adjusts the amplification of the gain stage (210). The AGC circuit (400, 500) determines whether the input signal to the amplifier (125) is a digital signal or an analog signal and transforms either signal into the frequency domain, thereby automatically adjusts the processing method depending upon the type of pilot carrier signal. The AGC circuit (400, 500) also possesses the ability to process a change in the frequency of a pilot carrier signal remotely.

Abstract: A reprogrammable subscriber terminal of a subscription television service which can have the control program code of its control processor modified by downloading new program code from the headend. The control processor stores a boot program in an internal read only memory. Upon start up and resets, the boot program determines whether the control program should be changed from a command sent from the headend. The command, termed a parameters transactions, includes the number of expected download program code transactions required to complete the control code modification, the memory space areas where the code is to be loaded, and the channel over which the download program code transactions are to be transmitted. The channel is tuned and when the boot program receives all the download program code transactions accurately and stores them, the boot program will cause the control program to be restarted at a selected address of the new or modified control program code which has been downloaded.

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: An ingress monitoring device (400) for monitoring and detecting reverse signals that may include ingress signals. The ingress monitoring device (400) includes a processor (430) for resolving the reverse signals into predetermined sub-bands at a first resolution. A power computation circuit (435) computes a power level for each of the sub-bands. A threshold comparison circuit (445) then compares the power level that is indicative to the power level of the ingress signals for each of the sub-bands with a predetermined threshold value. When ingress signals are detected by the ingress monitoring device (400), an alarm signal is sent that indicates the specific communications equipment in which the ingress signals have been detected.

Abstract: Systems and methods for a distortion monitoring system that detects an abnormal amount of signal distortion occurring in a transmission system. The distortion monitoring system includes a system amplifier section for amplifying and coupling an input signal to provide first and second outputs and a distortion monitoring section for processing the second output. The amount of distortion present is represented by an output from the distortion monitoring section of the system. In one embodiment, the distortion monitoring section can include an envelope detector for receiving the second output signal, a lowpass filter coupled to the envelope detector for cutting off frequencies below the Nyquist rate, and a voltage amplifier coupled to the lowpass filter for amplifying the signal.

Abstract: Variable rate multiplexer devices have, by definition, a variable output rate for bits of information encoded therein. As a result necessary time sync information such as program clock reference information cannot be guaranteed to be delivered within the time interval thresholds mandated by certain industry broadcast standards, such as MPEG-2 and digital video broadcast (“DVB”). Transmission of reference signals, such as PCR information, may be assured by inserting detection means to detect the time interval between occurrences of the reference signal. If the interval between occurrences of the reference signal exceeds a predetermined time interval threshold, the detection means will instruct a memory device to provide a reference signal, which is then imprinted with reference signal information and inserted into the stream of information being output by the multiplexer.

Abstract: A system for inputting conventional emergency alert messages into a digital subscriber television system. The method allows existing emergency alert equipment to interface with the digital system equipment in the headend of a digital subscriber television system. A unique identifier and the format of the digital emergency alert message allow the input of an emergency alert message and allow for a wide variety of optional data formats, system control options, and data storage options.

Abstract: An infrared (IR) keyboard having a communication protocol and a method for operating same includes circuitry for converting a standard recognized keystroke into a corresponding IR data word for transmission to an IR receiver. The IR keyboard includes circuitry and logic which determines the type of key being actuated and assigns a communication protocol based upon the detected key. An IR code word corresponding to the detected key is associated with the key press and is transmitted from the IR keyboard to an IR receiver using a protocol corresponding to the type of key detected.

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 a 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: An apparatus for indicating the configuration of a cable television line amplifier. The line amplifier contains a controller that senses a preset voltage on a status indication line. When the amplifier is reconfigured, such as by adding new circuits containing new functions or features, these new circuits contain resisters that are shunted to modify the preset voltage level on the appropriate status indication line. The controller senses the modified voltages and provides an indication of the new function of the new circuit to a headend through a cable television distribution system.

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 cable television system (100) includes forward and reverse paths. Reverse path circuitry within an optical node (400) of the system (100) receives reverse analog electrical signals from subscriber equipment (140) and generates therefrom a multiplexed reverse digital optical signal. The reverse digital optical signal is transmitted over a fiber optic cable 420 to a cable television hub (430), the reverse path portion of which includes no active circuitry. The hub (430) multiplexes the reverse digital optical signal with other reverse digital optical signals from other nodes to generate one or more forwarded digital optical signals at a hub output, wherein generation of the one or more forwarded digital optical signals requires only passive devices in the reverse path of the hub (430).

Abstract: An interface module included in a headend rack for enclosing electronic circuitry having a top, a bottom, and a back side that slides into the headend rack and connects to a backplane. The interface module includes a first planar surface connecting to the top side forming a first angle, a second planar surface connecting to the bottom side forming a second angle, and a front planar surface connecting the first and second planar surfaces. The first and second angles are equal and are obtuse. The interface module further includes a plurality of connectors extending from the first, second, and front planar surfaces for electrically coupling mating connectors with the enclosed electronic circuitry. The first, second, and front planar sides extend out of the headend rack, whereby the first, second, and front planar extended surfaces allow for a greater area for the plurality of connectors, thereby allowing conventional modules to be combined into one interface module.

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: The preferred embodiment of the present invention is a cable modem apparatus for reliably providing a personal computer access to the Internet through a cable television link and a public switched telephone network link. The invention includes: a cable television link failure detector connected to the cable television link; a message generator connected to the cable television link failure detector, where the message generator is configured to generate at least one message responsive to the cable television link failure detector; and a message transmitter connected to the message generator, where the message transmitter is configured to transmit the at least one message through the public switched telephone network link to cause Internet communications to be communicated to the personal computer through the public switch telephone network link.

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: 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: 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: 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 step 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.