Showing papers on "Communications system published in 1984"

Poker machine communication system

Abstract: A system for controlling the operation of electronically linked gaming machines which enables information to be transferred between machines and from each machine to a control unit. In particular, credits on a machine can be transferred to another machine and the credit state of each machine can be interrogated and adjusted from the central control unit.

Synchoronous packet voice/data communication system

Abstract: A packet communications network and apparatus for communicating information in voice and data packets transmits and receives voice and data in accordance with standardized frames of a standardized communications format such as a standard DS-1 type trunk. An apparatus is coupled to multiplex standardized channels into a single channel wherein voice or data signals are packetized into independently addressable packets synchronized on, for example, the DS-1 frame. The network includes voice and packet data concentration apparatus operable in a multiple node trunk environment to concentrate signals into independently addressable synchronously switchable packets, thereby to provide an efficient (high data capacity) interface between trunk terminations. Up to four times as much information can be transferred between nodes with the ability to switch between nodes as compared to conventional TDM and PCM communication without compression without the ability to switch between nodes.

Acoustic telemetry - An overview

Abstract: Acoustic telemetry from underwater submersibles and sensors has been pursued ever since it was recognized that the ocean could support signal transmission. While it has been evident that some form of communication is possible, the ocean has proved to be a distressingly difficult medium in which to achieve high data rates. High data rate transmission requires a wide bandwidth which is severely constrained in the ocean because of the absorption of high-frequency energy. Moreover, the ocean is a very reverberant environment with both time and frequency spreading of signals; this further limits data transmission rates. The net effect of the bandwidth and reverberation constraints has led to either acoustic telemetry systems with low data rates or to the use of tethered systems. Over the years, various forms of acoustic communication systems have been developed. These have included direct AM and SSB for underwater telephones, FM for sensor data, FSK and DPSK for digital data, and parametric sonars for narrow-beam systems. As offshore operations have increased, several other systems have been proposed and/or built to respond to particular needs. In this paper, we review the underwater channel and the limitations that it imposes upon acoustic telemetry systems. We then survey some of the systems that have been built (excluding military systems) and indicate how they use various communication system principles to overcome these limitations.

Railroad communication system

Abstract: A radio communication control system for a lead unit and a plurality of remote units is disclosed. The system has a protocol for establishing a communication link between the lead unit and the one or more remote units in the system which prevents any of the units in that system from processing messages or commands from other units in other train systems or processing messages or commands originating from units within a train system which are addressed to other units within the system. The communication system also includes a communications channel contention system for minimizing the probability of multiple units transmitting on the common communication channel at the same time and for insuring that the highest priority communications in each train are transmitted first in time measured from the end of the latest transmission on the radio communications channel. The invention also includes apparatus for verifying the establishment of the communications link by means of signaling through the mechanical coupling in the train and monitoring the radio response. The invention further includes an improved flow rate sensor for use in a remote unit for determining when significant air flows occur into the brake pipe of the remote unit. The invention further includes an air pressure regulation system which prevents the fluctuation of the air pressure in the equalizing reservoir of the lead and remote units consequent from either leakage or change in the ambient temperature.

Multiple access communications system

Abstract: A multiple-access communications system for an unlimited user population wherein a system controller continuously transmits Aloha signals on a slot-by-slot basis giving an updated number of time slots available whereby a calling party can select any one of the designated time slots at random. The calling party checks the time slot immediately preceding its selected time slot to ascertain if the current Aloha number is zero (or an equivalent thereof). If it is zero then the calling party reverts to listening for a time slot containing an Aloha number greater than zero. Alternatively if it is not zero the calling party apparatus sends a signal to the system controller in its selected time slot. Multipurpose signalling in each time slot can be carried out by the system controller thereby reducing the overhead on the system and speeding-up the setting-up of calls which may be off-air or non off-air.

Personal-servicing communication system

Abstract: A communication system offering specific services to specific persons bears a portable memory device with a record of personal information such as the bearer's identification number, class of service, personal data, etc. In making a call, the bearer of the memory device puts it on a communication terminal device and the terminal device reads out the personal information, which is transferred to a data processor such as a central processor in the exchange so that a service specific to the calling person is rendered.

Method for communicating variable length messages between a primary station and remote stations of a data communications system.

Abstract: A data communications system (Fig. 1) in which variable length messages (Figs. 3, 4 and 5) are communicated between a general communications controller (GCC 104) and a plurality of portable and mobile radios (130, 132, 134, 136, 138). The variable length messages (Fig. 3) include a bit synchronization field (204), a message synchronization field (205) and a plurality of channel data blocks (203) for efficiently and reliably handling long strings of data or text. Each channel data block (Fig. 5) includes an information field (503), a parity field (505) for error-connecting the information field and a channel state field (507) indicating whether or not the radio channel is busy or free. The GCC (104) is coupled to a cellular arrangement of channel communications modules (CCM's 106, 108, 110, 112), which each include a radio transmitter (114, 120, 124) and/or radio receiver (116, 118, 122, 126, 128). The mobile and portable radios (130, 132, 134, 136, 138) communicate with the GCC (104) by way of the CCM's (106, 108, 110, 112).

Variable bandwidth switching system

Abstract: A communications system that improves upon the availability of communications paths between devices and simplifies the connectivity requirements to communicate data and control information to and from a remote station (11). System nodes (21) are provided which are disposed along a time multiplex network signal stream. The nodes (21) serve to interface remote stations (11) to the network signal stream (25A, 25B) and may also switch information to different stations (11) connected to the same node (21). The nodes (21) are operative to allocate a variable bandwidth of the network signal stream for data communications between devices connected to different nodes. The nodes (21) include switching devices that may be configured to accomodate stations (11) that operate at different speeds. Allocation of bandwidth may be dynamically varied such that system resources are not unneccessarily diverted. Control of bandwidth allocation and internal switching within the node is accomplished via control information communicated to and from the node. Such control information may be contained within the network signal stream and decoded by the node (21) or communicated to the node (21) via a dedicated control communications line. Control information may be encoded into the signal stream communicated between the system node (21) and the remote station (11). Thus, communication of data and control signals between the stations (11) and the system node (21) does not require complex wiring. Accordingly, individual stations (11) may be more conveniently located.

Method and apparatus for bridging local area networks

Abstract: A communications system interconnects local Area Networks (LAN's) across broadcast simplex channels. The LAN's are connected independently and transparently of protocols above the data link layer so that the system appears to the user at a station in one Local Area Network as one large single network. A bridge interconnects the LAN's across simplex channels. The bridge is constructed to permit more than two local area networks to be interconnected across simplex channels to the bridge and to provide communication between stations.

System for carrying out spread spectrum communication through an electric power line

Abstract: A communication system for carrying out communication between a plurality of stations through an electric power line operating in a commercial power frequency band. Spread spectrum modulation of an information signal, employing a pseudorandom code sequence is used at a transmitting station. Spread spectrum demodulation is carried out in a receiving station to reproduce the information signal. The modulated signal is spread over a wide frequency band different from the commercial frequency band. Each station may comprise both of a transmitter and a receiver, and may be specified by a an assigned destination address that also is transmitted. The destination station address may be indicated either by an address signal or by an additional pseudorandom code sequence peculiar to a destination station. Alternatively, polling operation is carried out through the electric power line by a polling station to select one of the stations. Preferably, another pseudorandom code sequence is superposed on the modulated signal so as to specify a synchronization signal and different from the pseudorandom code sequences conveying the information signal and/or the destination address.

Distributed telephone system

Abstract: A communication system is provided for the interconnection of telephones and other instruments capable of communicating via the voice spectrum, the system providing a single transmission line such as a coaxial cable by which full duplex communication is provided between any pair of telephones. Each instrument is coupled to the transmission line by a control unit which includes computer operated transceiver equipment for paging other ones of the control units to initiate a telephonic communication. Each control unit is provided with an identification number and circuitry for recognizing the identification number contained within a paging signal so as to initiate a response. In a separate spectral portion of the transmission line, there are provided sets of analog communication channels each of which has upper and lower spectral portions to provide two-way communication in opposite directions between a pair of telephones engaged in communication. A transmitter and a receiver in each of the control units is provided for the communication of analog signals of both voice and data via the voice channel, each control unit including circuitry for tuning the transmitter and the receiver to the selected channel in accordance with digital data transmitted via the transmission line and specifying a selected one of the voice channels.

A Subjectively Adapted Image Communication System

Abstract: An interactive image communication system is described transmitting image information stored in a central database over low-bitrate channels. To shorten the transmission time, a data compression technique is applied in combination with a progressive image transmission procedure. Furthermore, human interaction is implemented in order to select specific areas for picture buildup or to reject additional image sharpening completely. The mean transmission time for each picture is essentially reduced if the transmission parameters of the investigated system are adapted to the visual threshold performance of the human eye. The adaptation is realized by means of the given classification algorithm. For a set of portrait pictures, more than 95 percent of the transmission time can be gained by this adaptation in comparison with PCM transmission.

Secured communications system

Abstract: Apparatus and method for reducing the cost and complexity of equipment placed on subscribers' premises in a subscription communications system, such as a cable television system, while at the same time providing security against unauthorized system access includes a microprocessor controlled frequency converter in proximity to the subscriber's premises to convert information transmission signals to subscriber-receivable frequencies; a channel selection unit at the subscriber's premises for producing a command signal to initiate the transmission of information to the subscriber; and a verification circuit coupled to receive the command signals, to verify the same and electronically to instruct the microprocessor. The microprocessor may be provided with plural, plug-in converter modules for feeding signals to several subscribers and may be made responsive to subscriber generated auxiliary function signals from alarm detector units, utility meter reading devices, and the like.

Zoned data communications system for communicating message signals between portable radios and a host computer

Abstract: A data communications system is described that covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated 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 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 CCM receivers receiving the same message signal and computes an adjusted signal strength for each zone. The GCC then selects the zone having the largest adjusted signal strength for determining the location of the portable radio that transmitted the message signal. Whenever the GCC transmits a message signal to a portable radio, the CCM transmitter is used that covers the zone having the largest adjusted signal strength for the last transmission from that portable radio. Since the GCC can be simultaneously transmitting message signals to portable radios in other zones using non-interfering CCM transmitters, information throughput is greatly enhanced.

Tamper-resistant, expandable communications system.

Abstract: An expandable, multipurpose digital and analog communications system in which a plurality of remote interrogator units (215, 216, 117) connected in a branch of the systems are isolated from one another by band stop filters (222, 228) to permit simultaneous polling without interference with other operations. Also disclosed is a premium service control unit (Fig. 7) which makes use of a frequency agile oscillator (702).

Communications system for transmitting and receiving data and voice signals simultaneously through 2-wire signal lines

Abstract: A communications system for transmitting and receiving data and voice signals simultaneously on 2-wire signal lines, which superposes and extracts high frequency modulated data signals using a high frequency transformer which is coupled to the 2-wire signal line. The transformer has two windings which are short-circuited with respect to high frequency components, but which pass low frequency voice signals between the 2-wire signal line and a low frequency hybrid circuit.

Frequency hopping data communication system

Abstract: An improved frequency hopped data communication system with a random transmission of mark and space frequency over the transmission bandwidth to provide independent frequency hopping of the mark and space frequency is provided in the system which is particularly immune to repeater jamming. Only one frequency is transmitted at a time upon selection on a bit instant by a pseudo-noise code generator. The location of the mark and space frequency is randomly chosen, however, the location is known at the transmitter and the repeater by appropriate synchronization equipment.

Mobile radio communication system

Abstract: of the Disclosure A mobile radio communication system having a plurality of fixed stations respectively connected to a plurality of subscriber's lines extending from a telephone exchange, and a plurality of mobile stations linked with the fixed stations through radio channels. Each of the mobile stations effect speech via one of the fixed stations. The system comprises means provided foe each fixed station for transmitting rate charging information from the telephone exchange to a mobile station under speech, and rate collecting means provided for each mobile station and being responsive to the rate charging information to vary its content.

Multiprocessor system employing dynamically programmable processing elements controlled by a master processor

Abstract: There is disclosed a multiple processor system which employs dynamically programmable processing elements (DDPE) utilized as slave devices and under the control of a master processor. A plurality of DPPE's have input/output data lines connected to a digital signal processing (DSP) bus. Communication between the DPPE's is afforded via the (DSP) bus from a master processor which interfaces with the bus via a dual port memory designated as a global memory. Each DPPE is connected together via another bidirectional serial bus so that the individual DPPE's can communicate one with the other in regard to processing and exchanging of arithmetic data. The digital signal processing bus allows the master processor to interface with the DPPE devices for control of input/output and control functions. In this manner, the master processor interfaces directly with a codec and has outputs which allow the transmission of plaintext or ciphertext data which data is formed by arithmetic operations performed by the slave DPPE's. The master processor also accesses a host computer and user terminal via a deuce circuit which essentially is a dual enhanced communications element. The status of the DPPE's and priority between the DPPE's and the master processor is controlled by an arbiter circuit which essentially controls the access of the DPPE's to the dual port memory (global memory) via the digital signal processing bus. The system is employed to operate on complicated algorithms and is patricularly adapted for use as a voice processor or modem processor is regard to modern communications systems.

Piezo-electric terminal station for communications system

Abstract: A terminal station for communication with one or more similar remote stations via mains wiring includes a piezo-electric coupler (22) whereby carrier signals are transmitted to and received from the line (24). The coupler is driven by an oscillator (21) modulated in correspondence with an input signal and tuned to the resonant frequency of the coupler.

Simultaneous voice and data communication and data base access in a switching system using a combined voice conference and data base processing module

Abstract: A combined telecommunications and data communications system operates by partitioning data wherein the PCM speech transmission data field is used to contain both digitized speech and other data in the same channel within a frame. Thus the system enables speech and data to be combined in a common information field and to be simultaneously transmitted in the same channel, frame by frame, through a digital switching network. The switching network contains a common port which has a digital interface connected to the port which digital interface can separate and combine the speech and the data fields. The digital interface is connected to a conference module which conference module receives the speech fields via a speech bus. The digital interface is further connected to a data base system which data base system receives the separated data fields via a data tone bus. Through the unique use of a digital interface for combining and separating speech and data fields from the information field of a channel, a conference module and a data base may both be connected to a single port thereby reducing the number of ports and network channels required for simultaneous conferencing and data base access.

Micro controlled classification yard

Abstract: A modular control system for a railroad classification yard is described. The control system can automatically perform those functions necessary to control the various elements of a railroad classification yard to enable the train of cars to be switched from a hump track to one of a plurality of bowl tracks in accordance with the destination for the car. The control system comprises a number of subsystems including a hump control system (HUMPCON), an operator communications subsystem (OPCOM), a switching control subsystem (MASC), a retarder control subsystem (MARC), a multidrop communications system (MDCOM), a crest monitor subsystem (CMON) and a distance to couple subsystem (MADTC). Some of the subsystems are implemented as singular modules (HCON, OPCOM, CMON). Other subsystems include multiple modules (MARC, MASC, MDCOM). Each module in each subsystem is comprised of a single microprocessor and related peripheral circuits. Data identifying each of the cars to be humped, and the required destination track is provided by OPCOM to HCON. The HCON module tracks the cars as they travel through the yard and maintains a data base indicating control system performance. HCON transfers data to other modules as required via MDCOM. In addition, as information is acquired from other modules, the data base is enlarged to record this information. At the conclusion of switching for a particular car or cut, the resulting data, termed "cut statistics" is transferred to OPCOM for hard copy printout.

Method and apparatus for selecting for use between data buses in a redundant bus communication system

Abstract: For use in a communications system in which a plurality of communication devices are connected to a plurality of buses in a redundant communication type system in which the same data is concurrently transmitted between the communication devices over the plurality of buses, a scheme determines which of the buses should be utilized for the reception of data through the examination of each of the buses for the existence of transmitted data. Upon determining that data is present on any of the buses, there is established a first period of time which terminates a fixed increment of time after data is absent from all of the buses. An indication is then provided for each bus which has data thereon during said first period of time and extending at least through a second fixed increment of time beyond that first period of time. The bus to be utilized is then selected from those which is found to have data during the first period of time on the basis of an algorithm which does not switch buses unless the bus previously connected to did not contain data.

Fault-tolerant communications controlller system

Abstract: The present invention relates to a system for controlling multiple communications lines, so that a computer system can operate with a single component failure. Two processors are used to control two communications controllers and each of the controllers control up to 15 line controllers. Each line controller has two ports and each port is connected to a communications controller thereby providing two communications paths to each processor. Redundant power supplies are also used to provide single failure fault-tolerance. A downloadable microprocessor board is provided in combination with, but separate from, an interface board that is designed to meet various communication format specifications and the line controller comprises the two boards.

Data communications system having overlapping receiver coverage zones

Abstract: A data communications system is described that covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated 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 has at least one transmitter and receiver for covering at least one zone. Each CCM receiver has a coverage area overlapping the coverage area of at least two other CCM receivers and at least a predetermined minimum probability P of successful reception of a transmission from a data radio located in its coverage area, such that the joint probability P J of successful reception of the transmission from the portable radio by at least one of the CCM receivers is expressed by the equation, P J =1-(1-P) 3 . Each CCM 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 CCM receivers receiving the same message signal and computes an adjusted signal strength for each zone. The GCC then selects the zone having the largest adjusted signal strength for determining the location of the portable radio that transmitted the message signal. Whenever the GCC transmits a message signal to a portable radio, the CCM transmitter is used that covers the zone having the largest adjusted signal strength for the last transmission from that portable radio.

Queued community repeater communications system

Abstract: A communication system which controls access to a single communications channel by a plurality of remote units arranged in predetermined groups is disclosed. Assignment of the channel is controlled by a central control station which provides time periods on the channel for remote units to request permission to transmit on the channel. As the channel becomes clear, the central control station transmits a grant of service to a requesting remote unit group permitting real time transmission of voice or data on the channel. At the conclusion of the transmission, the central control station detects an end-of-transmission condition and revokes the grant of service to the served remote unit group.

Design and performance analysis of a Digital Acoustic Telemetry System for the short range underwater channel

Abstract: This paper presents the design and performance description of a microprocessor based Digital Acoustic Telemetry System (DATS). The system was used to transmit data over short range underwater paths and to measure the fading characteristics of a group of CW tones. This work reports on the test results from Woods Hole Harbor. The system has also been used for under-ice propagation experiments in Lake Caanan, NH, and in the Marginal Ice Zone near Svalbard. Geometries chosen for the tests are representative of the short range marine work site paths for which high data rate communications systems are desirable.

Communication system and method

Abstract: A communication system for communicating analog and digital data with a process variable, e.g., pressure, transmitter over the two wires which supply power to the transmitter apparatus. The digital communication operation is half-duplex, bit serial transmission and is represented by the currents and voltages in the transmitter communication loop which are selectively introduced between process variable analog data transmissions of 4-20 ma. A plurality of bit cells are provided for each data word or byte between a start bit and a parity bit cell. Following the completion of transmission of the digital data, a predetermined time period is introduced to enable the resumption of transmission of process variable data. Multiple byte digital data transmission can also be effected between process variable analog transmissions by having a byte spacing less than the predetermined time period preceeding the 4-20 ma process variable transmissions. Thus, this method of communication provides for selective alternate digital and analog communications with the digital communications being achieved by variations of the current in the communication loop between the 4-20 ma limits, while the analog data is represented by a corresponding direct current magnitude between the 4-20 ma limits. Consequently, the variation of the loop current in a first format produces a digital communication capability while the variation of the loop current in a second format produces an analog data communication capability.

Routing architecture for a multi-ring local area network

Abstract: The architecture provides a frame format and procedure for routing messages through a single ring or multi-ring communication system. Stations associated with the exchange of messages are located on the single ring or on different rings of the multi-ring communication system. The rings are connected by bridges to form a local area network. The frame format includes a plurality of control bits positioned within a Routing Information (RI) field, a frame control field and a frame status field. Messages are generated and structured in accordance with the frame format. A group of the control bits, in each message, is set with initial values according to the message type. Thus, different messages are characterized by a different sequence of control bit settings. A routing algorithm analyzes the message and depending on the status of the control bits, the message is processed and ultimately switched to its proper destination.