Showing papers on "Communications system published in 1986"

Models for analysis of packet voice communications systems

Abstract: In a packet voice communication system, packets are fed to a common queue by a number of independent voice sources and are removed from this queue on a first-come-first-serve basis for transmission over a communication link of finite capacity. Each voice source alternates between active periods, during which packets are generated at regular intervals, and inactive periods, during which no packets are generated. In this paper, we discuss three models, a semi-Markov process model, a continuous-time Markov chain model, and a uniform arrival and service model, to assess the queueing behavior of such systems. Numerical results obtained from each of the three models are compared to each other, to results obtained from a discrete event simulation program, and to results obtained from an M/D/1 analysis. Parameters of the model are the average duration of active and inactive periods, the packet generation rate, the communication link capacity, and the total number of voice sources. Conclusions are drawn regarding which models appear to be most appropriate in the parameter ranges investigated.

Satellite communication system with random multiple access and time slot reservation

Abstract: A multiple access data communication system is disclosed wherein a communication channel is shared by a plurality of stations. The channel is divided into frames each being partitioned into time slots smaller in number than the number of stations of the system. A reservation status signal is constantly broadcast at frame intervals from a central station to all remote stations to indicate reserved status of the time slots. When a transmission request is made in a remote station, it discriminates a message signal shorter than the time slot length as a single packet having a time slot length and detects an idle time slot from the channel using the reservation status signal. If the message signal is longer than the time slot length, the station divides it into a series of packets of the time slot length and transmits a reservation request to the central station to receive from it a time-slot assignment signal and inserts the long-message packets to time slots specified by the time-slot assignment signal.

Line mounted apparatus for remote measurement of power system or environmental parameters beyond line-of-site distanc

Abstract: A remote sensing and communications system for installation on energized high voltage conductors is disclosed herein. The sensor modules are capable of measuring electrical, mechanical or environmental parameters in the vicinity of a high voltage conductor. The module digitizes and communicates the measured quantities via a communications subsystem mounted on and powered by an energized high voltage conductor without requiring a circuit interruption. Communications to a Central or Regional dispatch center at any desired distance from the sensing location is achieved using Ku-band or C-band spread spectrum satellite communications, or using the Geosynchronous Orbiting Environmental Satellites (GOES), or through fiber optic communications links. Individual subsystem modules are generally toroidal in shape and can be mounted on an energized high voltage conductor using a hot-stick or other means. The energized conductor current flow and electromagnetic field is used to generate a regulated power supply for the sensor module electronics. All the electronic components within the unit are protected by a signal conditioning network to preclude destruction of components in the event of lightning strike or other overvoltage conditions.

Data communications system

Abstract: A data communications system employing sliding window protocol where the size of the window of the sending or receiving station can be made selectable by the user according to the speed, length or error rate of the communication link or the frame size used to maximize the utilization of the communication link. The negative acknowledgements sent by the receiving station specifies the upper and lower limit of a range of identification numbers of frames unsuccessfully received to increase efficiency. Before data is transmitted, the sending and receiving stations exchange the preferred sets of link parameters and generate a modified set of link parameters to resolve potential conflicts. Either the sending or the receiving station stores a table defining the frame sizes for use with different bit error rates of the communication link. The station then evaluates the current bit error rate to select the optimum frame size from the table and adjust the frame size accordingly.

Terminal based adjunct call manager for a communication system

Abstract: An adjunct call manager unit connects to a station set port of a telephone communication system and receives button identification and status signals to determine line, agent, and feature activation status of the system. In response to one or more of the received status signals, commands are sent to the system using button depression commands and switchhook commands to effectuate call processing control over the system. In one embodiment, the adjunct unit functions as an automated call distributor for managing incoming calls to the system.

Bi-directional data telemetry system

Abstract: The data telemetry system disclosed is a complete data communications system suitable for use by utilities such as electronic companies, gas companies and water companies which can be used for meter reading and load management at individual subscribers premises (21). Elements of the system can also be used as a power load carrier in a premise specific local area network (LAN). With the system as disclosed, all 10,000 subscribers (21) per exchange can be serviced. It will be understood that data can be multiplexed between a central office location (25, 34, 44) and remote subscribers (21) for any suitable purpose with the data system as disclosed. A packet switching structure is disclosed having eight to thirty-two bytes in the data message. This packet is routed between the utility (28) and remote subscriber (21) with routing headers being added and deleted as required by the network modules (38, 40). Each successive layer of the multiplexing and switching hierachy submultiplies the aggregate 10,000 channel capacity into fewer channels. Both time and space division switching and multiplexing are used.

Communication system having automatic circuit board initialization capability

Abstract: A self-initializing communication system is described which automatically itializes circuit boards of the system using predetermined operating parameters when the system is initially powered-up or reset. The system is arranged to initialize circuit boards inserted in any order in any board slots of the system equipment housing. A malfunctioning circuit board can be replaced while the system is operating and the replacement circuit board is automatically initialized by the system using the stored operating parameters from the malfunctioning circuit board.

Voice and data communication system

Abstract: A telephone communication system for transmitting and receiving both voice signals and digital data signals, with no significant distortion to the voice signals and with substantially higher digital data rates than previously could be obtained in comparable systems. The voice signals are digitized, data compressed, and time-division multiplexed with the digital data signals, to produce a composite digital signal that can be transmitted over conventional telephone lines. The system can be selectively configured in a conventional telephone operating mode, in which the system transmits and receives merely the analog voice signals and all of its various digital circuitry elements are bypassed. The system is automatically configured in this conventional telephone operating mode whenever a significant failure in any of its individual units is detected.

Method and apparatus for reducing handoff errors in a cellular radio telephone communications system

Abstract: Wrong handoffs in a cellular radio telephone RF communications system can be minimized or eliminated without increasing locating receiver equipment requirements, field strength measurement time or system response time. Field strength measurements are made at handoff candidate cells and also at cells neighboring (geographically proximate to) those candidate cells. A weighted average of the measured field strength of the candidate cell and the field strength measured in cells neighboring the candidate cell is calculated for each candidate cell (the field strengths measured by neighboring cells may be multiplied by a weighting factor of 0.5). The weighted averages for the candidate cells are compared, and the candidate cell corresponding to the highest average is selected to handle the mobile transceiver call. Statistical analysis shows that this technique for determining handoff candidates significantly reduces the probability that a call will be handed off to a cell which is geographically distant from the mobile transceiver--even in the presence of propagation anomalies.

Infrared data communication system

Abstract: An infrared data repeater adapted for providing communication of infrared signals across an infrared transmission barrier comprises a pair of relay units mounted at opposite ends of a housing. The housing may be mounted in the wall of a building. Arrays of receiver and transmitter elements of the relay units are configured to provide communication over substantial solid angles. The relay units may be selectively directionally orientated. The elements define different effective pre-established solid angles of reception and transmission. The elements are arranged so that there is an inverse relationship between the solid angle and the distance between the element and a corresponding infrared receiver or transmitter.

Optical demand assigned local loop communication system

Abstract: A distributed, demand access local loop telephone system is disclosed. An optical fiber, or fibers, connect a central office and a plurality of remote units which are located near subscriber populations. Communications on the fiber is by high speed digital data stream which is comprised of a plurality of bit multiplexed PCM channels, each of bandwidth equivalent to a VF channel or greater. The remote units are connected to the subscriber equipment (e.g. telephones or other data sources/sinks) by subscriber dedicated links (e.g. wire pairs or other cabling), and the remote units may be added, subtracted, or moved along the fiber path to reconfigure the overall system. Because of the demand access nature, the fiber bandwidth can be dynamically redistributed among the remote access units at high speed and controlled at the central office. The topology of the system can also be reconfigured, within limits, from a central site. The system is T1 compatible, the data stream being the resultant of a plurality of T1 streams, and means is provided at the remote units for extracting and inserting one or more VF equivalent channels in any desired number up to and including an entire T 1 equivalent group.

Power line communication system

Abstract: A low-level, low-power radio frequency (RF) communications system designed to operate as a point-to-point power line communications sytem (PLC) utilizing frequencies from 50 to 600 MegaHertz (MHz) superimposed onto the AC power signal in a building.

Evolving electronic communication networks: an empirical assessment

Abstract: Understanding electronic communication and the patterns that characterize its development are critical to realizing full benefits from computer‐supported work. Cooperative work depends on effective communication and on the ability of organizations to manage the technology of communication appropriately. Organizations that do not understand the political and social dimensions of their communications system will inevitably fail to achieve their purposes.

Multi-step spread spectrum communication apparatus

Abstract: In a pseudo-random communication system, a transmitter-generated encoded signal is to be correlated with a receiver-generated similarly encoded signal for recognizing synchronization of the transmitted and received signals in the presence of undesired received energy. The system comprises a spread-spectrum transmitter including at least two pseudo-noise generators for producing at least two pseudo-noise signals which are related in a predetermined fashion, a mixer for receiving and mixing the two pseudo-noise signals with respective carrier and information signals to produce an output signal, and apparatus for transmitting the output signal. The system also includes a spread-spectrum receiver comprising a correlator and a matched filter coupled in circuit to form a synchronization detector circuit for receiving and detecting the encoded output signal transmitted by the transmitter so as to recover the information therefrom. The correlator includes at least one pseudo-noise generator for producing pseudo-noise signals related in a predetermined fashion to the pseudo-noise signals produced by the transmitter pseudo-noise generators and a mixer for mixing the pseudo-noise signals with the received encoded output signals and coupled in circuit with the matched filter circuit.

Bandwidth limits due to mutual pulse interaction in optical soliton communication systems.

Abstract: Mutual interaction between soliton pulses may severely limit the maximum bit rate of a soliton-based optical communication system We present explicit analytical results for soliton separation as a function of propagation distance in the presence of mutual pulse interaction In particular, we find that soliton coalescence can be avoided by proper phase shifting of consecutive pulses and that a phase shift of π/2 minimizes the initial mutual interaction

Multiple port service expansion adapter for a communications controller

Abstract: @ Bus interconnection between the system busses of a multi-port communications controller and the busses of one or more multi-port adapters is facilitated with a new architecture for providing an interconnection controller. A programmably adjustable adapter and port interface controller is combined via a scannerless communications controller with a bus interconnection control logic that handles both DMA and interrupt mode data transfers for a large number of channels. The invention provides an improved means for transferring data to or from numerous communication channel devices within a processor based communications system in such a manner that the optimum mode of data transfer may be individually programmed for each channel as system environment conditions demand.

Digital communication systems

Abstract: Digital communication systems , Digital communication systems , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Improvements in or relating to signal communication systems

Abstract: The invention comprises a low power broadcast system that is applicable especially to the so-called "electronic shelf" for retail stores, wherein the shelf edge carries price displaying modules that can be addressed and controlled from a central computer operated station. The system also permits the modules to broadcast back to the central station to confirm safe receipt of data and to give information as to stock levels, etc. A broadcast system avoids the need for wiring so that location changes are facilitated. To overcome the extremely noisy environment and to conserve power consumption, and hence battery life, the system employs a low frequency (132 kHz) reference carrier transmitted by the base station in discrete segmented packages, each of which frames a base data word transmitted by the base station and a corresponding module data word transmitted by the module a fixed period after the end of the base word; the base receiver then has precise time information for receipt of the module word and can "look" for it among the noise. The carrier received by the module is divided and the lower frequency used to demodulate the information-carrying transmission from the base station of the same frequency, avoiding the need for a phase locked loop detector; this lower frequency is also used for the module transmission. The module employs an air-cored loop antenna coil for the lower frequency and a ferrite-cored loop antenna for the higher reference frequency, while the store antenna is segmented for selection of the group of modules to be addressed; the antenna contacts the metal shelving to provide electromagnetic coupling thereto. Each module contains a microprocessor which controls the operation. Each module has "concealed" buttons which can be enabled and used to insert data to be transmitted therefrom. A charging circuit can be used as the power source employing the received RF carrier energy.

Data communications system transmitter selection method and apparatus

Abstract: A data communications system is described which comprises a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated co-located transmitters and receivers, and a plurality of portable radios. Message signals carrying alphanumeric information are communicated between the GCC and the portable radios by way of a radio channel. Each CCM receiver takes a signal strength measurement every time it receives a message signal from a portable radio. The GCC gathers the signal strength measurements from the GCC receivers receiving the same message signal and computes the radio channel path loss between the portable radio and each base/transmitter-receiver site which received that portable radio's message. The GCC next determines how much transmitter power each base transmitter site can deliver to the portable radio's receiver. The GCC can then determined (a) which sites are capable of delivering a message to the portable radio, and (b) which sites can be simultaneously used for other traffic without producing harmful interference to the first transmission. Since the GCC can manage the levels of co-channel interference, multiple messages may be simultaneously sent from several base transmitters to several portable radios. This mode of system operation provides for greatly enhanced information throughput.

Adaptively coded data communication system with half duplex and/or full duplex function

Abstract: An error correcting encoding method and a vehicle data communication apparatus based on the same for use in data communication via fading communication channels dominated by burst errors in the data communication among vehicles such as automobiles are disclosed. The error correction encoding method detects, as data sent from a transmitting side is received by a receiving side, any error contained in the received data as a frame error rate of error frames involved in block data or a bit error rate of error bits involved in the block data and selects an error correcting code in response to the frame error rate for encoding. The vehicle data communication apparatus according to the present invention profitably employs the method, and changes an error correcting code to be used on the transmitting side in response to the extent of errors involved in the received data detected by the receiving side of a remote apparatus.

The Residential Power Circuit as a Communication Medium

Abstract: This paper is a summary of work done to characterize the residential power circuit as a communication medium. Here the term residential power circuit refers to that part of the power circuit on the secondary side of the distribution transformer. This circuit is often used for communication signals for controlling appliances, security devices, and for other purposes. The frequencies of most interest in these systems range from about 100 to 200 kHz. The interface to this circuit is usually a 120 V or 240 V receptacle used to deliver power. These communication systems are called residential power line carrier systems. Other types of power line carrier are distribution line carrier and transmission line carrier both of which are used by the power utilities for communications purposes.

Emulator for computer system input-output adapters

Abstract: An optical fiber communications system includes an optical pathway defined as a closed optical loop with a signal source introducing a fixed frequency optical signal onto the loop as a reference signal for system wide propagation. Each terminal device in the system includes a thermally controllable bus tap resonator which can be controlled in a step-wise manner to support plural sets of resonant modes having corresponding different free spectral ranges with one mode of each supported set of resonant modes frequency locked to the system reference signal and another mode used for communications purposes. The bus tap resonators are thermally controlled to allow each terminal device to tune from a first set of resonant modes having a first free spectral range to another set of resonant modes having another free spectral range so that the frequency of the mode used for communications in the latter set will be different from that in the former set. The system reference signal source is preferably defined by a controllable resonant structure, such as a Fabry Perot cavity, which is controlled to lock to the frequency of a stabilized He-Ne laser. A laser diode operating in the desired wavelength band is controlled to lock the wavelength of its output to that of the one of the resonant modes of the stabilized Fabry Perot cavity to thus lock the frequency of the laser diode to that of the highly stable He-Ne laser.

Verbal computer terminal system

Abstract: A telephonic data communications system provides verbal communication of data in remote computer systems. The major components of the systems are a plurality of channels and a data processor. Each channel includes a text-to-speech translator for translating digitally stored textual data into analogue speech signals corresponding to the verbal expression of the textual data; a telephone interface for establishing a telephonic connection with a user by detecting incoming calls and by initiating calls; and an RS232 port for accessing a data base in a remote host computer system. The data processor includes software for controlling the communications protocols used by each channel, whereby each channel emulates a computer terminal suitable for communication with the remote computer system connected to that channel, and software for extracting selected data from the data received from the remote computer system. This system enables one to telephonically receive data from a remote computer without the need for a computer terminal and without needing to reprogram the remote computer to communicate with the telephonic data communication system.

A Wide-Band Local Access System Using Emerging-Technology Components

Abstract: Recent advances in optical transmission technologies hold forth the promise of abundant and low-cost bandwidth. Parallel advances in the fundamental technologies required for the construction of switching equipment result in a plethora of emerging technologies available for use by the systems designers seeking to define a wide-band ( > 100 Mbits/s per channel) communications system. This paper presents a concept for such a system intended for use in the local access segment of a communications network. Both the proposed underlying technologies and the systems concepts used in applying those technologies will be presented.

Advanced Digital Communications: Systems and Signal Processing Techniques

Abstract: From the Publisher: This extensive reference book includes data on systems and techniques for ISDN, speech coding, echo cancellation, digital speech interpolation, digital television, modulation and demodulation methods, correlative coding, interference considerations, mobile radio and satellite systems, and adaptive equalization. This unique volume comprises one of the most complete texts on digital communications engineering.

Method of determining optimal transmission channel in multi-station communications system

Abstract: In order to effectively avoid cochannel interferences in a multi-station communications system utilizing a plurality of channels in common, the order of transmission channels to be used is determined utilizing a transmission priority assigned to each channel. The subject matter is characterized in that (a) the transmission priority of a selected channel is raised if the selected channel is not used at another station, and (b) is lowered if the selected channel is used at another station. This means that the past use records of the transmission channels are accumulated so that a good channel can be selected with high probability. In other words, a transmission channel with high priority is still ready to be used even if it was not selected in the preceding selection.

Factors Influencing the Evolution of Acoustic Communication: Biological Constraints

Abstract: Numerous studies have investigated selective forces that appear to influence the evolution of acoustic communication systems. I review a number of constraints on evolution in these systems. A species'

Mobile radio communications system

Abstract: A mobile radio communications system for wide area mobile radio communications allows any two remote mobile stations to hold communications by way of a public switching network. A fixed station governing an area in which a calling mobile station is located sends to a switching network its own identification (ID) data and ID data associated with a mobile station which is connected to the fixed station by radio. Based on the two kinds of ID data, a called mobile station sees a telephone number assigned to the calling mobile station and a telephone number assigned to the fixed station which is associated with the calling mobile station.

Method and apparatus for coordinating independent communications systems

Abstract: A method and apparatus for coordinating the transfer of communications control from one independent radio communications system to another is disclosed. A remote unit which communicates data messages is associated with a home system which has a plurality of fixed sites and overlapping radio coverage areas. As the remote unit travels away from its home system, communications may be maintained by providing radio coverage from an independent roam system. The last message received by the home and roam systems from the remote unit has the associated radio signal strength and time of reception stored at each system. When a current message is transmitted by the remote unit and both the home and the roam system receive the message, the roam system time stamps the message and calculates the signal strength associated with the current message. If the amount of time elapsed between the last and the current message exceeds a predetermined amount of time or if the signal strength exceeds a predetermined threshold, the roam system requests transfer of control of the processing of the current message from the home system. When the home system receives this request, it calculates the difference in signal strength between the signal strength of the current message as received by the roam system and the signal strength of the current message as received by the home system. If the difference exceeds a predetermined amount, the request of the roam system to further process the message is granted.

Transparent single-mode fiber optical networks

Abstract: For the first time in the history of communications technology, single-mode fiber offers the possibility of truly transparent communications systems. In this paper we consider the application of single-mode fiber technology to optical networks and the evolution of the technology to all optical networks based on space or wavelength switching. Also discussed is the progress towards some early experimental networks.