Abstract:
Forward link communication is achieved utilizing a conventional television broadcast station, either utilizing an entire presently unused TV channel or in a shared TV mode, with the return link communication being achieved using narrow band communication techniques for relatively low data rate communication through conventional television receiver aerials to a central receiver near the television station transmitter. The carrier reference of a local AM radio station is used as a synchronizing reference for the data streams and to allow the very close sepraration of each band in the return communication link to allow a large number of remote receivers to simultaneously communicate in the reverse link. Alternatively, the TV Chroma subcarrier serves this purpose.
Abstract:
Public alert and advisory systems for the communication of emergency and/or other information from one or more central locations to a plurality of remote locations, such as, by way of example, information regarding a nuclear accident and evacuation procedures. This system utilizes conventional programming stations such as AM, FM or TV stations, central transmitting equipment, with the emergency information being modulated by a second modulation technique differing from the first modulation technique for the ordinary programming so that conventional manually operated programming receivers will not be responsive to the emergency information. The receivers of the system however, are responsive to the transmitted emergency information, so as to sound a warning alarm, display codes relating to evacuation or other information and/or receive and present audio information depending upon the specific configuration of the system. Normally the remote receivers are given recognition codes so that the receiver may be given different emergency information, either on an individual or on a group to group basis. Fault detection is provided by configuring the remote receivers to automatically provide a fault indication if not periodically reset by the communications link. A unique telephone link, also disclosed, can be used for reliability testing or for ordinary data communication. Various embodiments and features are disclosed.
Abstract:
A gate valve locking arrangement in which a steel bracket is clamped on a portion of the truss extending upwardly from the valve bonnet and supporting the gate valve spindle and wheel, the bracket having a rigid bar extending upwardly and capped by a L-shaped member seating against the inside of the wheel. The bracket may be secured in a fixed portion relative to the wheel by a cylindrical lock having a recess into which the vertical portion of the L-shaped member is inserted and locked, or by a padlock in certain applications.
Abstract:
A spread spectrum system provides bidirectional digital communication on a vacant television (TV) channel for simultaneous use by more than 75,000 subscribers using time and frequency division multiplex signals locked to horizontal and vertical sync pulses of an adjacent channel Host TV station. The system, whose operation is analogous to a radar system, comprises: (1) the Host TV station to send down-link sync and data pulses to subscribers during the horizontal blanking interval (HBI), (2) subscriber "transponders" which detect those signals and transmits up-link "echo" data pulses only during the HBI to eliminate interference to TV viewers, and (3) a central receiver which also uses the host TV sync pulses to trigger range gates to detect the up-link data pulses. In a preferred embodiment the central receiver employs directional antennas to determine direction to transponders and to define angular sectors partitioning the service area into pie-like "cells" which permit frequency re-use in non-contiguous sectors (like cellular radio). The system thus operates like a radar to measure elapsed time between receipt of TV sync pulses and receipt of transponder response pulses and measures bearing to transponders to thereby determine the location of fixed or mobile subscribers as well as provide data links to them. Transponders may share user's existing TV antenna or may operate on cable TV and could be packaged as "RF modems" for personal computers, as transceivers for mobile or portable use, or they may be integrated with a TV receiver to provide "interactive television".
Abstract:
Public alert and advisory systems for the communication of emergency and/or other information from one or more central locations to a plurality of remote locations, such as, by way of example, information regarding a nuclear accident and evacuation procedures. This system utilizes conventional programming stations such as AM, FM or TV stations, central transmitting equipment, with the emergency information being modulated by a second modulation technique differing from the first modulation technique for the ordinary programming so that conventional manually operated programming receivers will not be responsive to the emergency information. The receivers of the system however, are responsive to the transmitted emergency information, so as to sound a warning alarm, display codes relating to evacuation or other information and/or receive and present audio information depending upon the specific configuration of the system. Normally the remote receivers are given recognition codes so that the receiver may be given different emergency information, either on an individual or on a group to group basis. Fault detection is provided by configuring the remote receivers to automatically provide a fault indication if not periodically reset by the communications link. A unique telephone link, also disclosed, can be used for reliability testing or for ordinary data communication. Various embodiments and features are disclosed.
Abstract:
A bidirectional cable television system provides for transmission of signals from cable subscribers downlink in the same direction as the ensemble of television channels which the cable television system is already constructed to deliver. The subscriber signals may be transmitted over the cable in the blanking intervals of a cable television channel, using the T-NET technique described in U.S. Pat. No. 4,750,036. Alternatively, the signals may be carried over a dedicated channel, or transmitted cochannel along a cable television channel carrying ordinary programming by adding the subscriber information to alternating video frames in alternating polarity to achieve visual cancellation. The subscriber signals are collected after the last distribution line amplifier in the cable downlink. The collected signals are transmitted to a central receiver via wireless or other customary means such as a modem. The collected signals may alternatively be transmitted over the air to the central receiver in the blanking intervals of a broadcast television channel using the T-NET technique.
Abstract:
A bidirectional cable television system provides for transmission of signals from cable subscribers downlink in the same direction as the ensemble of television channels which the cable television system is already constructed to deliver. The subscriber signals may be transmitted over the cable in the blanking intervals of a cable television channel, using the T-NET technique described in U.S. Pat. No. 4,750,036. Alternatively, the signals may be carried over a dedicated channel, or transmitted cochannel along a cable television channel carrying ordinary programming by adding the subscriber information to alternating video frames in alternating polarity to achieve visual cancellation. The subscriber signals are collected after the last distribution line amplifier in the cable downlink. The collected signals are transmitted to a central receiver via wireless or other customary means such as a modem. The collected signals may alternatively be transmitted over the air to the central receiver in the blanking intervals of a broadcast television channel using the T-NET technique.
Abstract:
Communication system for either public or private electric power load management and distribution automation, and the like, wherein subcarrier signals are sent to a plurality of remotely located receivers and transmitters using an existing standard FM broadcast station. The broadcast signal is detected by a receiver which filters out the subcarrier component of the broadcast signal. The radio frequencies of the plurality of remotely located transmitters and receivers are closely spaced and synthesized from the frequency of the broadcast subcarrier and their time of transmission, digital bit streams, and message frames are all synchronized from the subcarrier signal. The FM broadcast station thereby orchestrates all communication activity to and from the plurality of remote locations to optimize traffic flow and maximize a priori information to all components to significantly increase reliability.
Abstract:
The inventor discloses a bidirectional communication system for electric power load management and distribution automation application, and the like, wherein outgoing control signals to a plurality of remotely located receivers and transmitters are sent using an existing standard AM broadcast station using small angle subaudible quadrature modulation. The broadcast signal is detected by narrowband synchronous receivers phase-locked to the carrier component of the broadcast station. The radio frequencies of the plurality of reverse link transmitters are closely spaced and synthesized from frequency of said broadcast carrier and their time of transmission, digital bit streams, and message frames are all synchronized from the broadcast signal. The broadcast station thereby orchestrates all communication activity to and from the plurality of remote locations to optimize traffic flow and maximize a priori information to all components to significantly increase reliability. A unique fast Fourier transform processor synchronized by the broadcast station is employed in the central receiver to detect back link transmission.
Abstract:
A bidirectional cable television system provides for transmission of signals from cable subscribers downlink in the same direction as the ensemble of television channels which the cable television system is already constructed to deliver. The subscriber signals may be transmitted over the cable in the blanking intervals of a cable television channel, using the T-NET technique described in U.S. Pat. No. 4,750,036. Alternatively, the signals may be carried over a dedicated channel, or transmitted cochannel along a cable television channel carrying ordinary programming by adding the subscriber information to alternating video frames in alternating polarity to achieve visual cancellation. The subscriber signals are collected after the last distribution line amplifier in the cable downlink. The collected signals are transmitted to a central receiver via wireless or other customary means such as a modem. The collected signals may alternatively be transmitted over the air to the central receiver in the blanking intervals of a broadcast television channel using the T-NET technique.