Showing papers on "Data transmission published in 1982"

Square root Kalman filtering for high-speed data received over fading dispersive HF channels

Abstract: This paper shows how to apply square root Kalman filtering to high speed data transmission on fading dispersive high-frequency (HF) channels. High data-rate HF transmission can be achieved by use of a single carrier bandwidth efficiency modulation that is demodulated with decision-feedback equalization (DFE). The DFE coefficients are updated adaptively by square root Kalman algorithms. Theoretical formulation and mechanization procedures for the square root Kalman algorithms are given. Computer simulation indicates that good error-rate performance can be achieved with these algorithms for rapid fading HF radio channels.

On random multiple-access communication and group testing

Abstract: We study the application of group testing to the design of efficient algorithms for random multiple-access communication systems. Both direct transmission and reservation systems are considered for various types of channel feedback. We propose and analyze algorithms based on conventional and generalized group testing techniques. The proposed algorithms outperform TDMA and algorithms based on binary tree search and possess certain optimality properties.

Data transfer network for variable protocol management

Abstract: A data transfer network uses an I/O subsystem to support a main host computer in managing data transfers to and from remote data terminals. The I/O subsystem may constitute one or more units called a Line Support Processor. The Line Support Processor uses internal processor means to control a plurality of line adapters each of which has a data-comm line to a data set or data terminal. Control operations by said internal processor permit selected line adapters to operate selected types of protocols using synchronous or asynchronous transmission. Data communication information and commands in high level language data are loaded into auxiliary memories in the internal processor means and into each line adapter where the internal processor means acts to convert this language data into usable protocols.

Digitized voice message storage system

Abstract: The invention disclosed is a system for receiving, storing and retransmitting voice messages. The system includes a plurality of digital computers operating independently in parallel to supervise the system's operation. The system also includes a conversion subsystem to which a plurality of telephone lines may be connected. The subsystem converts between analog telephone signals and digital data which the system uses for message storage. The conversion subsystem includes a plurality of semi-autonomous sub-subsystems, one per telephone line connected to the system. Each sub-subsystem includes a microprocessor and a random access memory for storing the microprocessor's program and for temporarily storing the digitized voice data. The microprocessor monitors the status of the telephone line and controls the operation of the sub-subsystem's conversion of signals between analog telephone signals and the digital data stored within the system. The system also includes a mass storage subsystem in which digitized voice messages may be stored indefinitely. Multiple, semi-autonomous data transfer paths interconnect the mass storage subsystem and each sub-subsystem to which individual telephone lines are connected. The presence of these multiple, semi-autonomous data transfer paths over which the digitized voice messages are transmitted adapts the system for highly reliable operation. The reliable operation of the system is further enhanced by means of error detection of multiple simultaneous sub-subsystem selection. This selection error detecting means automatically and instantaneously terminates sub-subsystem selection if an error is detected.

Large-Scale Integration of Hybrid-Method Digital Subscriber Loops

Abstract: This paper reports on studies concerning the feasibility of large-scale integrated realization of the circuits needed to provide hybrid-mode full-duplex digital transmission at 80 kbits/s or higher rates over standard local telephone loops. Alternative means of achieving the required 60 dB or so of echo cancellation have been studied in detail. The conclusion is that a combination of analog and digital circuit techniques permit practical MOSLSI realization of the complete modem, including filters, echo canceller, timing recovery, and A/D and D/A converters, without need for external circuit elements, trimming, or adjustments. The preferred system configuration has been evaluated by means of analysis, simulation, and laboratory and field measurements. A complete full duplex system, including an experimental NMOS integrated circuit echo canceller, was built and tested. Measurements showed a bit error rate lower than l0^{-8} with line attenuation up to 40 dB, operating at 80 kbits/s. We conclude that a fully integrated MOSLSI ciruit to implement all functions for a hybrid-mode digital local loop is entirely feasible.

Idle time slot seizure and transmission facilities for loop communication system.

Abstract: A time division multiplex loop communication system for voice and data is disclosed with multiaccess time slot seizure and data transmission capability from all station nodes without changing the idle, nonreserved, status of the seized time slot A method and station node apparatus sends bursty data packets from a node when a time slot is not busy serving a longer duration voice telephone call The apparatus eliminates the need for inefficient time slot request, acknowledgement and reservation procedures which require several TDM frames to complete and which are typically longer in duration than the bursty data packet to be transmitted All stations have access to all time slots for bursty data transmission under control of loop interface circuitry which statistically ensures the successful data transmission from all sending nodes The interface circuitry includes input and output buffers, slot and bit identification circuitry, bit stream retard circuitry, output selector circuitry, bypass decision circuitry, and data and voice insertion control circuitry comprising a slot decision control circuit, a seizure timing circuit and an acknowledgment check circuit

Method and apparatus for data transmission using chirped frequency-shift-keying modulation

Abstract: A method for transmission of digital data utilizes a carrier frequency offset in a first frequency direction for a first binary condition, and offset in a second frequency direction for the remaining binary condition, at the start of a bit time interval. The carrier frequency is swept in a preselected frequency direction during each bit time interval, to produce a chirped frequency-shift-keyed waveform in the frequency domain, for transmission of each bit of binary data. Frequency-shift-keyed demodulation is utilized at a receiving end, with the receiver synchronized to the transmitter bit time interval, to recover the transmitted digital data. Apparatus for data transmission using this chirped frequency-shift-keyed modulation waveform is disclosed.

On optimal finite-state digital transmission systems

Abstract: The digital transmission of signals by transmitters and receivers that are time-invariant finite-state machines were investigated in general form. An average distortion criterion is used. Some general structure theorems are proved and some examples given that show improvement in performance as the memories of the transmitter and receiver are increased. Many conjectures and unsolved problems are mentioned, and areas for further study are indicated.

A Hardware Efficient Passband Equalizer Structure for Data Transmission

Abstract: A passband digital equalizer is proposed which combines the functions of bandpass filtering and phase splitting with that of adaptive equalization. The new equalizer also provides the in-phase and quadrature outputs required for demodulation. Although input sampling is required at several times the symbol rate (for voice-grade channel applications), outputs need be computed only once per baud. This structure economizes either on front-end analog (phase splitter) filtering or on the number of multiplications required in a digital implementation of a phase splitter and an equalizer. The performance of a receiver incorporating the new equalizer is compared, experimentally, with a receiver using a conventional fractionally spaced ( T/2 ) equalizer.

IR Remote control detector/decoder

Abstract: A pulse code modulated (PCM) infrared (IR) remote control detector/decoder with improved noise immunity particularly adapted for use with a television receiver is disclosed. The IR pulses are modulated by means of a high frequency clock signal in translating the transmitted signal to a higher frequency, more noise immune portion of the IR spectrum. After receipt of the transmitted signal by a signal detector, the high frequency modulation is removed from the pulses which are then decoded. Under the control of a microcomputer, the decoder looks for the start data bit and, if received, the subsequent control instructions. When the data transmission has been decoded, the microcomputer activates the appropriate control outputs to the television receiver's tuner system to achieve the desired control function.

A 2-channel, 16-bit digital sampling frequency converter for professional digital audio

Abstract: A digital sampling frequency converter for arbitrary ratios of sampling frequencies is presented. It is based on a multistage interpolating filter, and on a novel time-domain control of the filter stages by signals derived from the sampling frequency clocks. Time-domain resolution of ±300 picoseconds is obtained, compatible with digital audio of 16-bit resolution. In addition to the filter design and implementation, measurement results are presented. They indicate that 16-bit accuracy is indeed achieved, even with asynchronous, drifting and time-varying sampling frequencies. A number of applications (digital mastering, program transfer between conflicting digital audio formats, pitch control with constant sampling frequency in digital recorders, error concealment, interfaces in digital transmission) are presented.

Simulator interface system

Abstract: A linkage between a host computer and a plurality of external devices, suchs a simulator system, utilizes a distributed processing network of individual data processors to process, control, and position data for transmission to and from said host computer on a data rate of change basis. A master processor interfaces with the host computer and is connected via a serial data link to a plurality of slave processors located at the external devices. Each processor determines the necessity for a transfer of data from its associated computer or device and controls data transmission therefrom accordingly.

Optical transmission system for high frequency digital signals

Abstract: A desire exists in the optical transmission of optical signals to co-transmit a service channel or telemetry signals in the form of an additional low frequency signal over the light conductor, since a remote feed line or a service channel is not always installed parallel to the light conductor length. The requirement exists for the transmission of the additional signal that, in addition to a low additional expense, no disruption of the actual useful signal can occur. To this end, the control signal of a laser diode transmitter is modulated with the signal to be additionally transmitted and this light component is coupled out at the receiving side. The structure is particularly useful in optical transmission systems for very high frequency digital signals with bit rates above 100 Mbit/s.

Increasing capacity of baseband digital data communication networks

Abstract: This invention provides broadband network capabilities for baseband digital collision detection transceiver equipment for communication between a plurality of data stations by affording simultaneous transmission of multiple channels over a broadband pass transmission link such as a coaxial cable. Thus, a fundamental carrier wave is transmitted on said link, received at local data stations and used to detect signals on different baseband channels for reception. For transmission the carrier wave typically is used for segregating a plurality of at least two transmission channels into typically single sideband upper and lower pass bands of baseband bandwidth capability adequately separated with guard bands to permit simple separation for receiving by means of pass band filters, etc.

Digital transmission system

Abstract: In a multi station communication network wherein interstation communications are carried out by transmitting packets of information in selected blocks of repeating time division multiplex frames, the calling station reserves a block for transmission of an answer packet from the called station.

Telemetry system with signal booster for digital data transmission through a transmission line

Abstract: A telemetry system for sensing remote physical events and for transmitting and boosting a digital data signal representing the sensed events on a transmission line (22), which comprises a master clock (24, 26) and a plurality of sensing stations (20) for sensing local data. The sensing stations (20) inject local data onto the transmission line (22) as a digital data signal, and a controller/receiver (28) receives the digital data. The master clock (24, 26) initializes the system timing and generates a sync signal. Each sensing station (20) includes a booster subsystem (40) for receiving the local digital data and for injecting the digital data onto the transmission line (22) as a digital data signal. During system start-up, each booster subsystem (40) claims a slot, in accordance with an organizational process, for injecting the digital data signal onto the transmission line (22). The booster subsystem (40) in each sensing station (20) further includes a booster circuit (60) for boosting the digital data signals which are propagating on the transmission line (22), as well as the sync signal. The booster circuit (60) comprises a negative impedance bistable device for enhancing the amplitude and rise time of the digital data signal. Each booster subsystem (40) further includes a switching mode regulator circuit (56) for converting a supply current on the transmission line (22) to a level voltage, thereby providing local power to the components of the sensing station (20).

Loop type data highway system

Abstract: A loop type data highway system in which a plurality of data transmission control stations (abbreviated hereinafter as stations) are connected to a single loop transmission line for data transmission and reception between any desired ones. A transmit station transmitting data makes a compare check to compare successive predetermined unit lengths of the transmitted data with the corresponding ones of the data returning after travelling round the loop, thereby detecting an error occurring during the data transmission when non-coincidence exists therebetween. A receive station receiving the data monitors the number of data words to be received, thereby detecting an error occurring during the data transmission when a data transmission end signal is detected prior to arrival of all the data words. Upon detection of the error occurring during the data transmission, the transmit station transmits the data transmission end signal to the receive station to inform the receive station of occurrence of the error.

Successive frame digital multiplexer with increased channel capacity

Abstract: A digital multiplexer accommodates a large number of information signal channels per digital transmission channel through use of an improved statistical coding technique and successive frame transmission. The information signals are encoded into transmission code words, the code words are ordered into successive transmission frames and the transmission frames are sent over a communications highway to a remote location. An executive conferencing arrangement is also provided which utilizes a difference signal technique to set up a conferencing arrangement wherein each communications channel carrying analog information is connected to each communications channel not carrying analog information.

Access control of data transmission network

Abstract: A system for controlling access to a data transmission network of a bus configuration. After a communication unit has completed transmission of a message block, the communication unit transmits a synchronization signal over the bus. Each of the communication units of the network which has a message block for transmission responds to that synchronization signal by applying to the data bus the logical ones of the address of the associated data station, or of a virtual address resulting from an algorithm performed on that station address, the logical ones being applied in sequence during respective bit intervals. During bit intervals of the logical zeros of the station address, or of the virtual address, the communication unit monitors the bus. If during such monitoring the communication unit detects a logical one on the data bus, the communication unit terminates transmission of its logical ones and awaits the next synchronization signal. Thus, the communication unit of the highest station address, or virtual address, obtains control of the bus and only one communication unit transmits a message block at any one time, assuring there is no interference or collision of message blocks. On initialization of the system, if a communication unit monitors the data bus for a preset time without receipt of any transmission, the communication unit first transmits a logical one to the data bus and then transmits the logical ones of its station address to gain control of the bus, by the procedure mentioned above.

Consecutive identical digit suppression system in a digital communication system

Abstract: TITLE OF THE INVENTION Consecutive Identical Digit Suppression System in a Digital Communication System ABSTRACT OF THE DISCLOSURE An encoder for suppression of a consecutive identical digit in a digital transmission system facilitates the reproduc-tion of a clock signal for regenerating reception data, and keeping the average signal level constant. According to the present invention, a single bit (x) is inserted for every pre-determined number (m) of input digits, and said insertion bit is a complement of the sign of the previous k bits where k is an integer satisfying 1?k?m. Preferably, the value k is 1. The present invention is useful for digital communications higher than 100 Mbits/second, in particular, in optical communications.

Local area networks

Abstract: A data transmission network includes a number of access controllers connected to a central hub. The hub includes an arbitrator to select only one access controller for data transmission. Upon selection of one controller all other controllers are disabled to prevent collision of data packets. An interlock prevents enablement of a disabled controller until the data packet received by the transmitter has terminated to prevent transmission of part of a data packet. Synchronization between the data and a master clock is obtained by an initial coarse synchronization and a subsequent fine synchronization. The coarse synchronization is obtained by generation of a number of identical signals with a time delay between each signal. A clock pulse latches to one of the signal paths to provide the initial coarse synchronization.

Supervisory and control system having dynamic significant change of values

Abstract: Communications methods and apparatus are disclosed for multiple subsystem intercommunication for supervisory and control systems such as can be found in heating, air conditioning, energy control and other environmental control equipment that are installed in buildings and the like. The present invention provides an improved system which includes improved distribution means wherein data from individual distribution panels is discriminantly transmitted to the host computer as a function of the present sampled data and the data previously transmitted, preferably wherein the present rate of data transmission to the host computer is determined as a function of the previous rate of transmission. The present invention provides distribution means wherein the characterization or definition of the specific function operations that are to be performed by individual control point apparatus can be carried out by instructions that are provided by an operator from a central or host computer. A distribution means is provided whereby the present rate of data transmission from a remote unit to a host computer may be selectively determined as a function of the previous rate of transmission from that remote unit, and may also be determined as a function of the rate of communication (bandwidth) of communication to the host unit from the remote units. Means are provided for adapting change of value band limits which must be exceeded for transmission of an information signal (corresponding to the sampled data signal) to be output from a remote unit to the host unit. Additionally, means are provided for adjusting the change of value discriminant band limits as a function of the sampled data signal.

Transducer apparatus utilizing fiber optics for data transmission

Abstract: A transducer apparatus utilizing fiber optics for data transmission is disclosed in which an output optical signal is encoded with information representative of a parameter being measured and the encoded optical signal transmitted to a remote measurement and control apparatus site for decoding. The transducer is adapted to receive an input optical signal, and converts the input optical signal into electrical energy to power a driver. An electrical drive signal, generated by the driver, has a selectively variable frequency representative of the parameter being measured. Using the electrical drive signal, the output optical signal is generated. The driver includes a variable frequency oscillator whose frequency of oscillation is dependent upon the parameter being measured.

Remote return loop control in a data transmission system

Abstract: In a return loop control system in a data transmission system having data transmission units such as modems connected at opposite ends of a transmission line, a return loop being formed at one of the data transmission units by a command signal from the other data transmission unit when the transmission line, modulator, demodulator, etc. are to be tested. Where a data to be transmitted is sent out a predetermined time period later than the send-out of a signal for establishing a communication status to the transmission line, a command signal for forming a return loop is sent out within the predetermined time period.

Data transmission for maritime and land mobiles using stored channel simulation

Abstract: Channel simulators with synthetically generated complex multiplicative and additive Gaussian distortions are widely used for investigating non-frequency-selective fading channels. An alternative is to record the channel distortions (i.e. amplitude and phase variations) by probing the real channel and to use these stored signals to control the simulator in the lab. This stored channel method (SCM) has been applied to the following mobile radio channels • satellite to ship • SAR emergency buoy to satellite • base station to land mobile for low data rates A collection of tapes has been obtained for these channels under various conditions. They were used to compare several data transmission schemes at different data rates and various S/N-ratios, but with the same replayed fading fluctuations. The SCM was used to evaluate low rate data transmissions (< 10 Kbit/sec) with various modulation schemes such as CBPSK, digital FM, and DPSK/FM. Bit error rate results are presented. The experience with the SCM, its advantages and limitations are being discussed.

Data communication system

Abstract: Herein disclosed is a data communication system in which a plurality of node equipments are linked to a common signal transmission line so that the data may be communicated between the respective node equipments. The data communication system is characterized: in that at least one of the node equipments includes means for generating and transmitting repeatedly for a predetermined period the channel which contains a data transmission bit and a validity bit for the former bit: and in that each of the node equipments linked to the common signal transmission line partly sends out the data through said channel and partly makes the validity indicating bit indicate an invalid state, when the speed of said data is so slower than the predetermined period of said channel that the data to be sent out for the predetermined period are out of time thereby to make it possible to effect the data transmission at an arbitrary speed shorter than said predetermined period. Herein also disclosed is a data communication system in which a plurality of node equipments are jointed by a common transmission loop line and in which the information of multiple channels is repeatedly transmitted for a predetermined period to said transmission loop line so that the channel information may be sent and received between terminal equipments linked to said node equipments. The data communication system is characterized in that an idential pattern for synchronization is inserted into and transmitted by the plural head channels of each period so that the synchronization is effected at each of said node equipments by detecting the synchronizing pattern received by means of a detecting circuit.

Data transfer system in which time for transfer of data to a memory is matched to time required to store data in memory

Abstract: A data transfer system comprises data retaining means for retaining n-bit digital data (n being an integer), serial/parallel data converting means for converting the n-bit digital data transferred from the data retaining means from parallel data to serial data or vice versa in synchronism with first clock signals generated at a first clock frequency, counting means for counting second clock signals generated at a second clock frequency, and control means for transferring the n-bit digital data from the data retaining means to the serial/parallel data converting means each time the counting means counts a predetermined number of clock signals.

System for providing several data terminals with access to a digital telephone line

Abstract: A line loop designed for the transmission of digitized voice samples as well as data words between an exchange and several subscriber terminals, not all of them necessarily equipped for voice communication, is connected through a modem to a bus with parallel branches extending to all the terminals, each branch including an outgoing-data lead, an incoming-data lead and two ancillary leads carrying clock pulses for the timing of data transmission and reception which are generated at the exchange. Each terminal, identified by a multibit address, is provided with an interface including a carrier sensor which detects the free or busy state of the line--during a time slot assigned to data transmission--on the basis of a certain protocol according to which an idle state is denoted by an unbroken succession of at least seven bits of predetermined logical value (here "1"). When a given terminal is ready to send out a message, a buffer store in the interface is enabled by the carrier sensor in the free state of the line to emit successive address bits which are compared to the instant line voltage for the possible coincidence of such a bit with a higher-priority bit ("0" in this instance) from another terminal. If so, the address emission is aborted; if there is no conflict, or if the terminal here considered prevails on every address bit, the line is seized for the transmission of the following data message to the exchange.

Data transmission network employing optical wave guide

Abstract: A single main optical wave guide section is employed for carrying signals both away from circuits monitoring a high voltage transmission system and toward circuits for causing the operation of switching equipment in the high voltage line Control circuit equipment which is remotely located from the high voltage power conductor receives and produces optical signals required for monitoring the system state and causing the operation of the protective equipment Transmitted and received signals are isolated from one another within the single line by branching the ends of the line into two branches which deal with monitoring signals and control actuating signals, respectively The branched optical fiber ends prevent transmission of signals from one branch to the other but permit the transmission of the signals from either branch to the main body or from the main body to either branch The main body can be divided into as many branches as desired

Design Considerations for a CO-Powered Distributed-Drop PCM Station Carrier

Abstract: A 24 channel pulse code modulation (PCM) station carrier system has been developed which is powered by the repeatered DS-1 span line and also possesses distributed-drop capability. These features were realized by bridge powering the span line repeaters and efficient power utilization at the subscriber terminals. The design philosophy behind this unique system capability is given along with an operational description of some key circuit designs. The resulting system offers unusual flexibility and very low per-channel cost. Even though the span line termination and powering is selfcontained, the system occupies about half the rack space of comparable systems. The system described is among the first to provide the qualities of digital transmission with the application versatilities and cost of analog station carrier.