Abstract: A method and apparatus for improving communication throughout a network is disclosed. The network includes a module capable of transmitting messages in response to a change of state. Bit errors transmitted within network are detected and a detected bit error rate is calculated. A residual, i.e., undetected, error probability is determined in response to the detected bit error rate. Corrective action towards reducing the effects of the residual errors is taken, e.g., retransmission of messages, in response to the residual error probability exceeding a predetermined threshold.

Abstract: A power transmission and data communications system for use in a gas or oil well borehole is disclosed. The borehole includes a casing and a piping structure therein and at least one downhole equipment module located therein. The system provides for a power signal to provide power transfer to downhole systems that require power and for data and control signals to be transmitted using orthogonal frequency division multiplexing (OFDM) to the downhole equipment located in the downhole equipment modules. In particular, the system provides for the data signal to be electrically coupled to the case and piping structure for transmission downhole to the downhole systems that are similarly coupled to the casing and piping structure. The downhole equipment includes a power supply that is operative to recover electrical power from the power signal and to provide output power to the other downhole equipment.

Abstract: A power transmission and data communications system for use in a gas or oil well borehole is disclosed. The borehole includes a casing and a piping structure therein and at least one downhole equipment module located therein. The system provides for the power signal that is used to provide power transfer to be modulated with data and control signals that are to be transmitted to the downhole equipment located in the downhole equipment modules. In particular, the system provides for the power/data signal to be electrically coupled to the case and piping structure for transmission downhole. The downhole equipment includes a power supply that is operative to recover the power signal portion of the power/data signal and to provide power to the other downhole equipment. A downhole receiver is operative to recover the data portion of the power/data signal and to demodulate the data provided thereon.

Abstract: A reprogrammable data communications system for use in a gas or oil well borehole is disclosed. The borehole includes a casing and a piping structure therein and at least one downhole equipment module located therein. The system provides for data and control signals to be coupled to the casing and piping structure by a surface modem and transmitted to the downhole equipment located in the downhole equipment modules. The downhole equipment modules include a downhole modem that is coupled to the casing and piping structure and receives the transmitted data and command signals and recovers the transmitted data and commands therefrom. A downhole processor is coupled to the downhole modem and receives the data and commands from the downhole modem and stores the data and commands in retentive memory that is coupled to the downhole processor. In this way, the downhole processor can be reprogrammed with new algorithms and communications parameters.

Abstract: A personal identification system for use in security and various other types of pattern matching applications provides accurate recognition of a known person. This system uses a large quantity of course but inexpensive sensors to create a profile of a person seeking to enter the controlled space or to take other action. These sensors measure different statistically independent characteristics of the person, such as height, weight, stride, voice timbre, and time to perform various functions. The measurements so obtained may individually be of very low resolution. They are used to search a data base of patterns related to admissible individuals. Active agent methods are used to support learning and adaptation of the sensor set to address sensor drift and individual characteristic changes over time. A combination of many parameters will identify a person with very low probability of both false negative and false positive errors.

Abstract: A system utilizing adaptive frequency-hopped spread spectrum modulation to communicate over AC power lines and other noisy communications channels is described. The system employs a modulation structure in which individual packets of data are transmitted with FSK modulation using two frequencies chosen from a larger set. An error coding system is used which provides a controlling microprocessor with data on the quality of reception at each transceiver in the network; this information is used to alter the gain of the receiver, the bit rate of the transmission, and the specific frequencies employed by the network, in real time, to optimize communication error rate. Messages are organized in packets. A Master transceiver, controlling network management, transmits channel control information to other transceivers on the network, enabling system synchronization, acquisition of an existing network by new subscribers, and changes to the bit rate and frequency set in use.

Abstract: A system for digital communication over a wire lain along the path of guided vehicles to a modem and a loop driver, the modem providing high frequency signals and the loop driver providing low frequency control signals. Instead, the modem and the loop driver are connected to one end of the wire and the other end of the wire is connected through an impedance matching network to earth ground. The impedance matching network provides an impedance approximately equal to the impedance of the wire at the frequency of the high frequency signals. The impedance matching network may conveniently comprise an inductor (choke) in parallel with a capacitor connected between the end of the wire and earth ground and a plurality of resistors connected in parallel with said inductor and capacitor. The resistors are selectively clipped to eliminate the echo bringing the impedance of the impedance matching network to approximate equality with the impedance of the wire at the frequency of the high frequency signals.

Abstract: The system comprises transceivers employing identical modems, one located at a fixed position and connected to the wire and one on a vehicle guided along the wire. The transceiver's specialized modems may be connected to a central host which may be a computer, to a programmable controller, or to a communications bus as required. Additional transceivers may be connected to the communications bus for communication between the central host and additional wires. All central host signals are transmitted to all wire connected modems and sent out on all wires. All signals from vehicle modems are transmitted back to the central host. Each transceiver is adapted to employ one or more identical modem, each connected to a different wire.

Abstract: Messages are transmitted on pairs of frequencies that are orthogonal, that is the frequencies have no least common denominator (are prime to each other). A message is transmitted on the first of the pair of frequencies and, simultaneously, its complement is transmitted on the second of said pair of frequencies. The message is then retransmitted on another pair of orthogonal frequencies. In the second transmission, the message is remapped, such that, adjacent bits in the first transmission are not adjacent in the second transmission and the same bit in the first transmission and the second transmission are not spaced 1/120th of a second apart. Information is collected on the data error rates at each receiver. This information is periodically transmitted to a central frequency controller which collects this error information and determines the error rates on the frequencies being used. A hill-climbing technique is used to choose pairs of frequencies having the lowest current data error rates.

Abstract: A multi-drop local area network utilizes alternating current power lines as a transmission channel. Identical transceivers are used as a master and as up to 255 slaves. Each transceiver comprises modulator and demodulator units and a microprocessor control unit which may be connected to a host. The modulator and demodulator are connected to the alternating current power line through a high pass filter comprising a split bobbin, iron core transformer having an air gap which also provides impedance matching. The demodulator includes a clipper and analog circuitry providing a band pass filter and generating a square wave corresponding to the received carrier. A state machine acting as a digital filter produces a received carrier signal only when each half cycle of the carrier square wave is of the proper duration and the carrier signal has existed for slightly more than one half of the transmitted bit duration, which is a predetermined number of carrier cycles.

Abstract: An improved programmable controller having the ability to use two different data bases while presenting to the outside world a uniform word size. The programmable controller includes pipeline processing and hardware solution of a user control program in a network node format. A memory management scheme is provided allowing for the direct addressability of one-half million words by utilization of a page register. The programmable controller can be incorporated into a network containing other programmable controllers. The programmable controller also incorporates a multi-task interrupt so that the processor can handle more than one job at any particular time. Input/output tasks are handled logically in the scan solving the user networks rather than being based upon a particular physical area of the controller memory.

Abstract: An improved programmable controller having the ability to use two different data bases while presenting to the outside world a uniform word size. The programmable controller includes pipeline processing and hardware solution of a user control program in a network node format. A memory management scheme is provided allowing for the direct addressability of one-half million words by utilization of a page register. The programmable controller can be incorporated into a network containing other programmable controllers. The programmable controller also incorporates a multi-task interrupt so that the processor can handle more than one job at any particular time. Input/output tasks are handled logically in the scan solving the user networks rather than being based upon a particular physical area of the controller memory.

Abstract: A small, low cost, programmable controller is described capable of solving user programs represented in networks having up to seven rows and eleven columns. A column solver is utilized to provide efficient and fast solution of the user control network. The programmable controller also solves calculate functions having multiple outputs to facilitate use of the output information in the control program.A programming panel using a CRT display shows one or more selected control networks and, in conjunction with the central processing unit of the programmable controller, provides for the insertion of networks between two existing networks. Since the networks are solved by the controller mainframe in a sequential fashion, this network insertion allows the user to optimize his or her control program when solution order of the networks is important.