Showing papers on "Data transmission published in 1980"

Frequency domain data transmission using reduced computational complexity algorithms

Abstract: In this paper we describe a frequency domain data transmission method to be used for digital data transmission over analog telephone lines which exploits recently derived reduced computational complexity algorithms, such as the Winograd Fourier Transform, to achieve a significantly lower computational rate than comparable time domain QAM modems implemented digitally using signal processing techniques. In addition to the lower computational rate, the proposed method also allows for better channel bandwidth utilization by allowing optimal signal power allocation based on the channel's signal to noise versus frequency characteristics. Experimental results on this method are presented, indicating that it may be possible to send over 10,000 BPS over an unconditioned telephone line while maintaining a 10-5BER.

Carrier and Bit Synchronization in Data Communication--A Tutorial Review

Abstract: This paper examines the problems of carrier phase estimation and symbol timing estimation for carrier-type synchronous digital data signals, with tutorial objectives foremost. Carrier phase recovery for suppressed-carrier versions of double sideband (DSB), vestigial sideband (VSB), and quadrature amplitude modulation (QAM) signal formats is considered first. Then the problem of symbol timing recovery for a baseband pulse-amplitude modulation (PAM) signal is examined. Timing recovery circuits based on elementary statistical properties are discussed as well as timing recovery based on maximum-likelihood estimation theory. A relatively simple approach to evaluation of timing recovery circuit performance in terms of rms jitter of the timing parameters is presented.

Repeatered, multi-channel fiber optic communication network having fault isolation system

Abstract: A repeatered, multichannel fiber optic communication network includes a plurality of full duplex fiber optic channels and one or more auxiliary channels. In order to supervise and control the operation of the network, for both data transmission and fault/maintenance actions, each terminal station contains a processor-based subsystem capable of network monitoring, first level maintenance action, fault isolation, and remote network control and status reporting. This processor-based subsystem interfaces with each fiber optic channel, with an orderwire communication link, and with external input/output devices and surveillance equipment. Three substantially autonomous processor-based sections which are dedicated to performing specific functions within the overall network operation are employed for carrying out these separate interfacing tasks. Each section of the processor-based subsystem in a terminal station contains its own CPU and associated memory and is programmed to carry out specific functions identified with that section. Each section is interconnected with the other two so that, internally, the subsystem is fully integrated.

Service integrated communication transmission and interchange system

Abstract: A service integrated communications transmission and switching system for audio, video and data, between a user terminal and a central switching station of a telephone system wherein the line connecting the user terminal with the switching station includes at most one light-conductive fiber which is utilized in wave multiplex duplex operation for the transmission and reception of signals from and to the user terminal; the narrowband services are provided by means of digital transmission with analog to digital and digital to analog conversion and multiplex and demultiplex taking place at the user end; and the broadband services are provided by means of analog transmission.

Analog memory for storing digital information

Abstract: The present invention is directed to an analog memory for storing digital information in analog signal form. Typically, digital information is stored in digital signal form, where each digital bit is stored in a separate digital memory cell. In accordance with the present invention, an analog memory such as a charge transfer device (CTD), bubble memory, or magnetostrictive memory is used to store analog signals. Each analog signal is representative of a plurality of digital bits, thereby providing storage for a plurality of digital bits in each analog memory cell. Use of such an analog memory in combination with a digital system facilitates a hybrid memory, where digital information is stored in analog signal form. In one embodiment, a digital to analog converter is used to convert digital information from a digital processor to analog signal form for storage in an analog memory and an analog to digital converter is used to convert analog signals stored in the analog memory to digital signal form for processing with the digital processor. In another embodiment, an analog read only memory is used to store a program for a stored program digital computer in analog signal form. Storage of digital information in analog signal form increases the efficiency of storage because a plurality of digital bits can be stored in each memory cell. An embodiment having analog error compensation utilizes a reference signal for adaptive compensation of errors. Various systems using such memories are disclosed including signal processors, stored program computers, reverbation systems, and others.

The bandwidth of digital data signal

Abstract: The engineering of data communications systems invites involvement with a number of rather refined parametric concepts, such as bit error rate (BER), antenna gain, radiated power, communication efficiency, and bandwidth. Of these, none has been the subject of more lively discussion and revision than bandwidth. The implications of bandwidth can vary considerably from context to context, as the profusion of definitions of bandwidth will attest. The purpose of the present article is to explore the subject of data transmission bandwidth through an examination of its various definitions. The spectrum is finite, yet as technology manipulates it, a dazzling increase in bandwidth capability emerges.

Supervised wireless security system

Abstract: An ultrasonic communication system capable of wireless installation and supervised operation is achieved by communicating each information bit as two distinct ultrasonic frequencies separated in frequency enough to assure that the signal strength of both transmissions will not be in a deep null at the receiver location at the same time. The transmissions can be coded with a format that recognizes the correct data transmission even if reception of one frequency is lost. By use of transponders and other auxiliary units with periodic polling, supervised operation throughout a building can be maintained with events such as intrusion, fire or emergency as well as failures of particular units of the system reported.

Radio frequency controlled light system

Abstract: A light control system includes a transmitting unit (10) having a receiver unit address (22) and an output address switch (24) for pulse modulating a digitally encoded transmission signal broadcast by a radio frequency oscillator (26). A remotely located receiving unit (28) controls the power supply to an electrical load (42) such as an electrical light in response to digitally encoded data signals transmitted by said transmitting unit (10). The receiving unit (28) includes a radio frequency receiver (32) to apply a signal to digital transmission decoders (34) and a receiver unit address decoder (36). Upon detecting a transmitted signal encoder for said receiving unit (28) an output latch (38) sets an opto-isolated relay circuit (40) to connect or disconnect power to the electrical load (42).

A single-chip digital signal processor for voiceband applications

Abstract: A single-chip digital signal processor utilizing parallel multiplier and 3μ NMOS technology will be presented. Development can implement 41 second-order digital filter sections for 8kHz sampling of voiceband signals.

Data transmission in a drill string

Abstract: Data is transmitted through a drill string by means of acoustical energy by transmitting an acoustical signal for a first predetermined interval and ceasing transmission of the signal for a second predetermined interval to represent a first binary state; ceasing transmission of the signal for a third predetermined interval to represent a second binary state; and combining transmission and cessation of transmission of the signal in binary sequences representative of borehole data.

Method of and apparatus for monitoring digital transmission systems in which line transmission errors are detected

Abstract: A periodically reset flip-flop is set when an error is detected in the bit stream of a digital transmission link being monitored. A counter is incremented in response to each period during which the flip-flop is set and is decremented in response to a plurality of periods during each of which the flip-flop is not set. An alarm signal is produced if the count reaches a certain value. In the presence of the alarm signal, the number of error-free periods which must occur to decrement the counter is increased. The arrangement is less sensitive to error bursts causing false alarms than bit-error-rate monitoring arrangements.

Combined telephone and data-transfer system

Abstract: Telephone lines extending between a central office and associated subscriber stations are provided at opposite ends with mutually complementary modems and with couplers by which code signals from subscriber-operated address selectors can be sent to a common data network containing specialized information or to associated data-retrieval units. The latter are connected in parallel to a bus originating at a data bank from which data bits grouped into pages are continuously emitted at high speed. Each retrieval unit comprises two shift registers, one of them being loadable from the bus by the incoming high-speed bits to store a complete page together with an accompanying address code while the other receives a selected address code from the associated subscriber. A comparator, upon detecting an identity between the coded addresses stored in the two registers, stops the loading of the first shift register and commands its readout over the subscriber line at a slow rate compatible with that line's bandwidth. At the subscriber station the incoming data are displayed on a viewer of a data terminal or, with the aid of an adapter, on a television receiver. The transmission of address codes and other data over any subscriber line occurs between the two modems thereof at frequencies outside the voice band.

Line driver circuit for a local area contention network

Abstract: This disclosure relates to a line driver circuit for a station in a data transmission network, which driver circuit is adapted to drive the channel medium with a constant current so that conflicts or collisions with data transmissions from other stations will be cancelled out thereby preventing any particular station from dominating reception of a neighboring station. Each station is adapted to operate in a cyclic mode for contending for access to the network channel where a three-state cycle is employed, which states are the idle state, the packet-being-transmitted state and the acknowledgment period state. Each station will not begin transmission until it determines that the tunnel is in an idle state. Once the station has determined that the channel is idle, it will then delay for a period of time that is randomly chosen and, if the channel is still idle, will then begin transmission. Following transmission, the channel will again be quiescent for a short period of time before the acknowledgment signal is transmitted from the receiver. Each packet of data to be transmitted is of a fixed length so as to provide for synchronization between the various stations contending for access to the channel.

Fading channel communications

Abstract: Adaptive processing can reduce the effects of fading on beyond-the-horizon digital radio links. Two radio propagation channels for beyond-thehorizon communications, troposcatter, and HF are currently being reexamined. In the past, transmission over these radio channels had been considered unreliable due to fading effects. Recently, conversion from analog to digital transmission and the use of new adaptive signal processing techniques have offered promise of acceptable network communication quality. In addition, over-the-horizon radio provides economic and/or secu-· rity advantages relative to satellite, cable, or line-of-sight terrestrial microwave links. There is renewed interest in . the use of high frequency (HF) and troposcatter communications for networks carrying digital traffic.

Data transmission system for an endoscope apparatus

Abstract: Data transmission/reception devices are provided in endoscope, photographic attachment and light source unit. The data transmission/reception devices are connected with one another by two-way data transmission lines.

Cash flow monitoring system

Abstract: A computerized monitoring system which incorporates the power lines that provide electrical power to the remote devices as the physical communications medium of a serial data bus for the computer system. The system comprises a central computer and a plurality of computerized sensor modules within the individual remote devices. The central computer and each of the sensor modules has associated with it a respective data link for coupling respective signal generating and receiving means to the power distribution lines and for manipulating the signals to and from a form suitable for transmission on the power distribution lines. Phase shift keying is used wherein binary bits of data are represented as 180° phase shifts of the pulses in a carrier pulse train. A data transmission rate of approximately 15,000 baud with a carrier frequency of 120 kHz is typical. A polling signal includes a preamble of pure carrier frequency, followed by the serial number of the device being polled, followed by the data (or instructions) defining the message content. Each data link has its own clock for generating a pulse train at a frequency very close to the common carrier frequency, and includes means for bringing its own carrier frequency pulse train approximately into a predetermined phase relationship with the carrier train that is appearing on the power lines.

Even-odd parity checking for synchronous data transmission

Abstract: A synchronous data transmission system between remote stations is shown wherein data is transmitted parallel by bit serial by group over a plurality of parallel lines extending between sending and receiving stations A parity line is also included in the transmission system for checking errors and a clock line is included for synchronization of the parallel data being transmitted Information is transmitted from one station to another with alternating even and odd parity for succeeding groups of parallel data The information is checked at the receiving station for even-even or odd-odd parity in succeeding groups of data Longitudinal redundancy checking (LRC) is also added to the checking at a receiving station The combination of the even and odd parity checking and the LRC checking provides a level of data transmission error checking which is almost as effective in finding errors as a far more costly CRC checking mechanism The checking arrangement is adaptable to serial-by-bit transmission systems, as well

Introduction to Communication Science and Systems

Abstract: 1. Antennas and Transmission.- 2. Sources of Noise.- 3. Signals and Frequencies.- 4. Modulation and Noise.- 5. The Link between Continuous and Pulsed Signals-Sampling and Digitization.- 6. Autocorrelation and Stationarity.- 7. Pulse Shape, Filtering, and Arraying.- 8. Random Pulses and the Gaussian Distribution.- 9. Random Processes and Gaussian Signals and Noise.- 10. Some Aspects of Data Transmission.- 11. Limits to Error Performance: Information Theory.- 12. Applying Information Theory-Coding and Randomization.- 13. Sources, Source Encoding, and Source Characterization.- References.

Modem control device code multiplexing

Abstract: A modem is described for transmitting digitally coded information between an information distribution network and a data processing unit, which modem is responsive to modem control instructions provided by the very same keyboard input providing data transmission. The modem is capable of distinguishing modem control instructions from data transmission and includes such control functions as automatic telephone answering, automatic redialing of busy numbers, and an automatic escape sequence for terminating data transmission.

Data transmission/receiving device having parallel/serial and serial parallel character conversion, particularly for data exchange between communicating data processing systems

Abstract: In a data transmitting/receiving device having parallel/serial and serial/parallel character conversion, particularly for data exchange between communicating data processing systems, and being arranged between a local data processing system and a data modem terminating a data communication line for the purpose of controlling data transmission and/or reception procedures and containing a procedure store, and in which a random access storage is provided as a data buffer for intercepting data jams is provided along with an interrupt control for interrupting processing operations in a microprocessor in respect of higher processing priority, and in which a timer is provided for setting optimum transmission speed, first and second modem connection lines are provided and data messages to be transmitted are converted bit-oriented or character-oriented by the microprocessor from data groups supplied thereto by means of corresponding input switching commands. In addition, the optional transmission of bit-oriented data messages according to the synchronous data link control (SDLC) method or according to the high-level data link control (HDLC) method is provided.

Bus fault detector

Abstract: The present invention comprises computer system equipment useful for detection of faults in data transmission within a computer system. Fault detection is accomplished by monitoring the current flow through a digital signal source means, which is characterized in that it only draws significant current during a non-transition period when a fault condition occurs.

Data network employing a single transmission bus for overlapping data transmission and acknowledgment signals

Abstract: This disclosure relates to a network of stations having a single transmission bus. A bus assignment control line is daisy-chained to all of the stations to form a closed loop such that an assignment signal will circulate through the loop and return to the originating station after each station has been given an equal chance to be serviced. Once the bus is assigned to a station, data is transmitted over it and the receiving station returns an acknowledgment signal over a separate acknowledgment line common to all stations. The station that sent the transmission will accept acknowledgment signals only during a finite period of time after its own transmission so as not to be interrupted by other acknowledgment signals at a later time.

Transmitting additional signals using violations of a redundant code used for transmitting digital signals

Abstract: At a transmitter of a digital transmission system which uses a redundant transmission code to transmit data, at least one predetermined code combination which occurs randomly in the encoded data is selectively modified, to form a predetermined code violation, in dependence upon an additional signal which is to be transmitted. At a receiver, the predetermined code violation is detected and corrected to reproduce the additional signal and the data. By selection of appropriate code combinations and violations more than one additional signal can be transmitted. The arrangement is particularly suitable for transmission of additional signals, which may comprise protection switching signals or a digital voice channel signal, via fiber optic transmission links using 2AMI encoding.

Digital transmission system with a double analog integrator Delta Sigma coder and a double digital integrator Delta Sigma decoder

Abstract: Delta-Sigma noise-shaping coder with two analog integrators and Delta-Sigma decoder with two digital integrators. The coder comprises an operational amplifier with two analog integrators in its feedback loop and two cascaded flipflops both connected to the input of the operational amplifier through resistors having a predetermined ratio. The configuration of the integrators is particular and results of the identification of the z-transfer function of the coder to be designed with the p-transfer function of a known integrator (p, Laplace's variable). The decoder comprises a digital integrator-filter of order two and two cascaded flipflops both connected to the input of the filter through amplifiers having gains in a predetermined ratio.

Contrasting fiber-optic-component-design requirements in telecommunications, analog, and local data communications applications

Abstract: This paper contrasts the system requirements in the three major applications of fiber optics: digital telecommunications, analog, and local data communications. These comparisons reveal how differing system requirements result in very different architectural design for the fiber optics components, particularly the receiver design. Some alternative receiver architectures are discussed along with performance tradeoffs.

Digital television transmission using bandwidth compression techniques

Abstract: It has been shown that interframe coding techniques provide an effective means to reduce the transmission bit rate of video signals without sacrificing picture quality The channel capacity of various coding schemes over existing digital transmission links is listed For digital satellite, for example, even a single television (TV) channel cannot be transmitted by conventional PCM, whereas one or two channels of TV can be transmitted by employing efficient coding techniques However, much greater advantage is obtained by use of interframe coding Three network quality TV signals can becarried through a transponder For teleconferencing applications, a single satellite transponder can managuep to 20 simultaneous conference signals on a TDMA basis, if one uses a 3M bit/s interframe coder Our satellite experiment has demonstrated excellent performance for network digital TV application The TRIDEC teleconferencing system has been commercially used by NTT in Japan since 1979 and the NETEC-6/3 interframe encoder is being seriously considered for application in North American teleconferencing applications

Data compression techniques and applications

Abstract: Several data compression methods are reviewed for signal and image digital processing and transmission, including both established and more recent techniques. Methods of prediction-interpolation, differential pulse code modulation, delta modulation and transformations are examined in some detail. The processing of two-dimensional data is also considered.Results of the application of these techniques to space telemetry and biomedical digital signal processing and telemetry systems are presented.Some of the considerations and comparison criteria presented, even though not completely general because extracted from experimental results, can be useful in selecting and defining the more pertinent data compression system for the different practical applications.

An LSI digital signal processor

Abstract: An integrated circuit digital signal processor has been designed and built to realize a variety of important telecommunications applications. The flexibility of full stored program control and the processing speed of a pipelined architecture are essential to this general purpose device. Special emphasis has also been placed on circuit interface features which simplify the use of the processor as a system element.

Digital transmission error reduction

Abstract: In a transmission system, reconstruction of a portion of the signal lost in transmission is based on signal encoding at the transmitter, and decoding at the receiver; at the transmitter, sequential portions of the signal are intermixed to form encoded portions, and autocorrelation factors (waveform feature signals) of the original portions are added to each encoded portion to form a packet; at the receiver, any missing packet is reconstructed from the adjacent received packet.