Zenith Electronics Corporation

Zenith Electrics Corporation

Semir D Sirazi

Gordon E Reichard, Jr

Angelo A Bione

Charles B Bestler

Thomas E Zinger

Thomas J Rossen

John K Chan

The disclosure depicts in a two-way broadband communications network employing a carrier sense multiple access with collision detection protocol an apparatus and method for controlling station transmit signal levels. Signal level detection circuitry is coupled to one or a plurality of locations in the network transmission medium to determine the signal level generated by each of the plurality of stations periodically transmitting into the medium. The detected signal level from a station is compared to a predetermined range of appropriate values for the station and where the station is transmitting signals outside of the predetermined range, a correction factor is applied to the station to adjust the transmit levels of the station.

Method and apparatus for power level control in area networks

An IPPV technique is provided for a cable system having one-way addressable converters. Each of several central offices in a metropolitan area will provide ANI information representing the cable subscriber's phone number and a code representing the cable event to be viewed or cancelled. The data is sent asynchronously to a respective telephone communication unit located at the central office. This telephone communication unit (TCU) does some buffering, eliminates unnecessary data, and sends data synchronously to a telephone communication controller (TCC) located at the cable headend station. The TCC will acknowledge the data. There will be several TCCs located at the cable headend station corresponding to the several central offices who may give telephone service to the cable operator's subscribers. All of these TCCs at the headend station are coupled through a multiplexer to a system controller. Each TCC provides intermediate processing which converts the subscriber's telephone number into binary. The multiplexer provides buffering, flow control, and arbitration among various TCCs. The multiplexer adapts to data flow conditions. The system controller receives data from each subscriber, locates a corresponding home terminal unit address, examines the password and other information, and maps the two digit program identification which was entered by the subscriber into an authorization code. It then authorizes the home terminal units in accordance with the IPPV requests by transmitting the subscriber's cable address and a new authorization code in the vertical blanking interval, generates the commercial transaction, and downloads the transaction to a billing system.

Mapping method for impulse pay per view system

A broadband communications network includes a plurality of stations interconnected through selected forward and reverse channels by a network translator. Each station continuously monitors the forward channel for detecting the presence or absence of a forward channel carrier. A given station is allowed to transmit a data packet as modulation of the reverse channel carrier only after the expiration of a predetermined time interval during which no carrier is detected on the forward channel. By establishing the predetermined time interval for each respective station in inverse relation to the distance of the station from the network translator, a synchronized transmission time base as well as equalized station access is achieved for improving network performance.

Communications network with individualized access delays

An IPPV technique is provided for a cable system having one-way addressable converters. Each of several central offices in a metropolitan area will provide ANI information representing the cable subscriber's phone number and a code representing the cable event to be viewed or cancelled. The data is sent asynchronously to a respective telephone communication unit located at the central office. This telephone communication unit (TCU) does some buffering, eliminates unnecessary data, and sends data synchronously to a telepone communication controller (TCC) located at the cable headend station. The TCC will acknowledge the data. There will be several TCCs located at the cable headend station corresponding to the several central offices who may give telephone service to the cable operator's subscribers. All of these TCCs at the headend station are coupled through a multiplexer to a system controller. Each TCC provides intermediate processing which converts the subscriber's telephone number into binary. The multiplexer provides buffering, flow control, and arbitration among various TCCs. The multiplexer adapts to data flow conditions. The system controller receives data from each subscriber, locates a corresponding home terminal unit address, examines the password and other information, and maps the two digit program identification which was entered by the subscriber into an authorization code. It then authorizes the home terminal units in accordance with the IPPV requests by transmitting the subscriber's cable address and a new authorization code in the vertical blanking interval, generates the commercial transaction, and downloads the transaction to a billing system.

Impulse pay per view system and method

An adaptive window multiplexing technique. A multiplexer is coupled between a single destination and a plurality of data sources. The multiplexer includes control circuitry for sequentially addressing each of the data sources. When a data source has data available for transfer, the sequential addressing is interrupted and the addressed data source is allowed to transfer all of its data to the multiplexer. After data in one source is completely transferred, the next data source is addressed.

Adaptive window multiplexing technique

A communications system includes one or more channels each comprising a plurality of LANs having multiple stations. The LANs of a particular channel are interconnected by a bridge interface, the respective bridge interfaces being connected by a backbone network. Each station is capable of transmitting a data packet including a header having either a 0 or 1 bridge flag, LAN stations being responsive only to data packets having a 0 bridge flag and bridge interfaces only to packets having a 1 bridge flag. Intra-LAN communications are thus effected by data packets having headers with 0 bridge flages while inter-LAN communications are effected by transmitting a packet with a 1 bridge flag from a source station which is coupled to the destination station by the bridge which also changes the bridge flag to 0. A special 'broadcast' header is used to effect communications when the LAN or channel of the destination station is unknown.

Bridging techniques for local area networks

A combination watchdog timer and input voltage level detector circuit is coupled to a microcomputer (or microprocessor) for insuring proper operation thereof under various conditions. The watchdog timer is coupled to the microcomputer and is responsive to a status signal output by the microcomputer indicating the operating state thereof. Failure of the watchdog circuit to detect the status signal indicates that the microcomputer has become unstable or is in a locked up condition and causes the watchdog circuit to initiate a microcomputer reset by means of a reset trigger circuit. A voltage level detector is coupled to the input voltage source and to the reset trigger circuit for similarly initiating the resetting of the microcomputer in the event the input voltage to the microcomputer drops below a predetermined value. When power is initially applied, a power up detector coupled between the voltage level detector and the watchdog timer ensures that the reset trigger circuit maintains the microcomputer in a reset condition until the input voltage reaches a predetermined level to permit normal microcomputer operation. The present invention thus ensures that the microcomputer is maintained or is placed in a reset condition in the event of input power transients, upon initial application of power to the microcomputer, and upon the occurrence of irregularities in microcomputer program execution.

Microprocessor reset with power level detection and watchdog timer

A CATV channel assignment system and method for arranging CATV channels in a tiered fashion facilitates selective viewer access to predetermined groups of CATV channels. A 'logical' channel number is generated upon channel selection and is provided to a microcomputer which, in turn, generates a corresponding lock-up PROM address. The logical channel number is converted by means of the thus generated address to a 'physical' channel number in the PROM. The physical channel number represents a standard CATV channel and is provided to the microcomputer for synthesizing the correct tuning frequency via a phase lock loop and conventional tuning circuitry. For a two cable system automatic cable switching is provided to permit channels on either cable to be included within the same group of selected channels. The present invention facilitates the 'tiering' of CATV channels into predetermined groups of channels, wherein each group has a viewer access authorization level associated therewith, and in which all channels in a group may be assigned logically related channel numbers, e.g., consecutively arranged channel numbers, while the corresponding standard channel numbers may be widely disparate and unrelated in a given group. This arrangement facilitates viewer channel selection by organizing subscribed-to channels into easily remembered numerical sequences and simplifies selective accessing of CATV channels by arranging these channels into two or more tiers where the channel numbers in each tier are logically related and not randomly assigned.

Growing community of inventors

Chicago, IL, United States of America

Semir D Sirazi