Showing papers on "Data transmission published in 1994"

Wireless Infrared Communications

Abstract: The use of infrared radiation as a medium for high-speed short-range wireless digital communication is discussed. Available infrared links and local-area networks are described. Advantages and drawbacks of the infrared medium are compared to those of radio and microwave media. The physical characteristics of infrared channels using intensity modulation with direct detection (IM/DD) are presented including path losses and multipath responses. Natural and artificial ambient infrared noise sources are characterized. Strategies for designs of transmitter and receivers that maximize link signal-to-noise ratio (SNR) are described. Several modification formats are discussed in detail, including on-off keying (OOK) pulse-position modulation (PPM), and subcarrier modulation. The performance of these techniques in the presence of multipath distortion is quantified. Techniques for multiplexing the transmissions of different users are reviewed. The performance of an experimental 50-Mb/s on-off-keyed diffuse infrared link is described.

Communication Systems Engineering

Abstract: (NOTE: Each chapter concludes with Further Reading and Problems.) 1. Introduction. Historical Review. Elements of an Electrical Communication System. Communication Channels and Their Characteristics. Mathematical Models for Communication Channels. Organization of the Book. 2. Frequency Domain Analysis of Signals and Systems. Fourier Series. Fourier Transforms. Power and Energy. Sampling of Bandlimited Signals. Bandpass Signals. 3. Analog Signal Transmission and Reception. Introduction to Modulation. Amplitude Modulation (AM). Angle Modulation. Radio and Television Broadcasting. Mobile Radio Stations. 4. Random Processes. Probability and Random Variables. Random Processes: Basic Concepts. Random Processes in the Frequency Domain. Gaussian and White Processes. Bandlimited Processes and Sampling. Bandpass Processes. 5. Effect of Noise on Analog Communication Systems. Effect of Noise on Linear-Modulation Systems. Carrier-Phase Estimation with a Phase-Locked Loop (PLL). Effect of Noise on Angle Modulation. Comparison of Analog-Modulation Systems. Effects of Transmission Losses and Noise in Analog Communication Systems. 6. Information Sources and Source Coding. Modeling of Information Sources. Source-Coding Theorem. Source-Coding Algorithms. Rate-Distortion Theory. Quantization. Waveform Coding. Analysis-Synthesis Techniques. Digital Audio Transmission and Digital Audio Recording. The JPEG Image-Coding Standard. 7. Digital Transmission through the Additive White Gaussian Noise Channel. Geometric Representation of Signal Waveforms. Pulse Amplitude Modulation. Two-Dimensional Signal Waveforms. Multidimensional Signal Waveforms. Optimum Receiver for Digitally Modulated Signals in Additive White Gaussian Noise. Probability of Error for Signal Detection in Additive White Gaussian Noise. Performance Analysis for Wireline and Radio Communication Channels. Symbol Synchronization. 8. Digital Transmission through Bandlimited AWGN Channels. Digital Transmission through Bandlimited Channels. The Power Spectrum of Digitally Modulated Signals. Signal Design for Bandlimited Channels. Probability of Error in Detection of Digital PAM. Digitally Modulated Signals with Memory. System Design in the Presence of Channel Distortion. Multicarrier Modulation and OFDM. 9. Channel Capacity and Coding. Modeling of Communication Channels. Channel Capacity. Bounds on Communication. Coding for Reliable Communication. Linear Block Codes. Cyclic Codes. Convolutional Codes. Complex Codes Based on Combination of Simple Codes. Coding for Bandwidth-Constrained Channels. Practical Applications of Coding. 10. Wireless Communications. Digital Transmission on Fading Multipath Channels. Continuous Carrier-Phase Modulation. Spread-Spectrum Communication Systems. Digital Cellular Communication Systems. Appendix A: The Probability of Error for Multichannel Reception of Binary Signals. References. Index.

Adaptive receiver structures for asynchronous CDMA systems

Abstract: Adaptive linear and decision feedback receiver structures for coherent demodulation in asynchronous code division multiple access (CDMA) systems are considered. It is assumed that the adaptive receiver has no knowledge of the signature waveforms and timing of other users. The receiver is trained by a known training sequence prior to data transmission and continuously adjusted by an adaptive algorithm during data transmission. The proposed linear receiver is as simple as a standard single-user detector receiver consisting of a matched filter with constant coefficients, but achieves essential advantages with respect to timing recovery, multiple access interference elimination, near/far effect, narrowband and frequency-selective fading interference suppression, and user privacy

Adaptive receiver structures for asynchronous CDMA systems

Abstract: Adaptive linear and decision feedback receiver structures for coherent demodulation in asynchronous code division multiple access (CDMA) systems are considered. It is assumed that the adaptive receiver has no knowledge of the signature waveforms and timing of other users. The receiver is trained by a known training sequence prior to data transmission and continuously adjusted by an adaptive algorithm during data transmission. The proposed linear receiver is as simple as a standard single-user detector receiver consisting of a matched filter with constant coefficients, but achieves essential advantages with respect to timing recovery, multiple access interference elimination, near/far effect, narrowband and frequency-selective fading interference suppression, and user privacy. An adaptive centralized decision feedback receiver has the same advantages of the linear receiver but, in addition, achieves a further improvement in multiple access interference cancellation at the expense of higher complexity. The proposed receiver structures are tested by simulation over a channel with multipath propagation, multiple access interference, narrowband interference, and additive white Gaussian noise. >

Data transmission system and scheduling protocol for connection-oriented packet or cell switching networks

Abstract: In connection-oriented packet or cell switching networks, a data transmission system and scheduling protocol utilizes both synchronous transmission and asynchronous transmission in an alternating pattern to provide each user with both a guaranteed transmission bandwidth or capacity to accommodate real-time communications, and bandwidth sharing among users to increase network utilization, while simultaneously eliminating network congestion to avoid data losses. The synchronous time slots provide for the bandwidth guarantees, while the asynchronous time slots are used to transmit data when a part of a previous synchronous time slot is not used. The asynchronous time slots also permit asynchronous data transmission using unallocated time within a given time frame. In one embodiment, time frames for data transmission are provided in which each time frame is composed of synchronous transmission times interspersed with asynchronous transmission times. For a given time frame, alternating synchronous and asynchronous transmission times are specified by a controller which determines the pattern of this alternation. In a preferred embodiment, the pattern is altered using novel timed-round-robin scheduling which transmits cells of data of respective connections over an outgoing link depending upon the synchronous transmission time allocated to each connection. To avoid data losses, asynchronous transmission is permitted only when a downstream switch indicates sufficient buffer space to accommodate asynchronous transmission from an upstream switch.

Translation and connection device for radio frequency point of sale transaction systems

Abstract: A device is provided that interfaces with existing point of sale credit card reading devices, and furnishes the option of transmitting data over either the existing modem installation or a radio frequency data communication network. The device scans the information encoded on the credit card to determine which data transmission path is appropriate for a particular transaction. The device software generates the necessary signals to simulate the normal interaction between the POS cardreader device and a modem. The software also converts between serial and packetized data in order to request and receive credit card purchase authorizations over the radio frequency data communication network.

Digital signal processing in communication systems

Abstract: From the Publisher: A great deal of modern communications equipment is being converted from analog to digital technology. This timely book explains many of the important concepts related to digital signal processing in easy-to-understand discussions of communications techniques, data transmission, filters, and hardware. Readers are given practical information on how to apply theory and algorithms to the design of radio receivers and transmitters. Among the areas discussed are analog to digital conversion - with emphasis on noise and distortion performance; manipulation of complex signals - positive and negative frequencies, plus Hilbert transformers; digital filters - guidelines for performance in communications, plus decimation and interpolation; hardware - multiplier accumulators, fast Fourier transform processors, digital signal processors, data flow techniques in equipment, and hardware simulation and testing; and speech processing - linear predictive coding (LPC), code excited linear predictive coding (CELP), and how to digitize speech at low data rates. Development of algorithms for oscillators, detectors, modulators, automatic gain control circuits, and other devices is clearly explained. Specific algorithms are provided for AM modulation, frequency modulation, FM detection, threshold extension, audio compression, automatic gain control, and squelch circuitry. Explanations of basic concepts of digital signal processing and data transmission are accompanied by reviews of signal representations, sampling, convolution, and z-transforms. Extensive real-world examples contribute to expertise in many facets of incorporating digital technology into devices. This hands-on treatment of DSP will help communications engineers upgrade their skills in digital signal processing and make a smooth transition into the design of more advanced systems. It also meets the needs of students who want to bolster their knowledge in communications.

Mobile access to an ATM network using a CDMA air interface

Abstract: The paper presents a possible integrated system concept for a direct sequence spread spectrum CDMA radio access system suitable for third-generation mobile radio. The system has been conceived to take account of such diverse services as low bit rate voice and quasi-broadband services at rates of up to 256 kb/s. Broadband services imply the use of the ATM transmission technique, and particular attention is paid to the mutual impact of CDMA and ATM. An efficient automatic repeat request technique is described which gives a suitably low overall error rate and a soft capacity limit. The proposed solution represents a quantum advance on today's CDMA solutions and integrates well with the ATM fixed network. >

Method and apparatus for controlling congestion in a communication network

Abstract: A scheme for controlling a congestion in the communication network, capable of realizing a recovery from the congestion state by the operation at the lower layer level for the communication data transfer alone, without relying on the upper layer protocol to be defined at the terminals. In a communication network including first and second node systems, a flow of communication data transmitted from the first node system to the second node system is monitored and regulated by using a monitoring parameter. On the other hand, an occurrence of congestion in the second node system is detected according to communication data transmitted from the second node system, and the monitoring parameter used in monitoring and regulating the flow of communication data is changed according to a detection of the occurrence of congestion in the second node system.

Credit enhanced proportional rate control system

Abstract: A system for controlling traffic in a digital communication network to avoid data loss due to congestion utilizes an integrated credit-based and rate-based traffic control approach, and adjusts the rate at which data is transmitted from a source in accordance with feedback in the form of rate and credit adjustment information from a network reflecting the ability of the network to transmit data and the destination to receive data In one embodiment, a source end system sends out resource management cells composed of various fields containing rate and credit information The intermediate systems of the network and the destination end system update the corresponding fields according to their congestion status and send the resource management cells back to the source end system so that the source end system controls the data transmission accordingly In a preferred embodiment, a source end system calculates an allowed cell rate from each of the fields in a resource management cell, and the minimum one among them is used to control data transmission

System and method for remote mirroring of digital data from a primary network server to a remote network server

Abstract: A system for remote mirroring of digital data from a primary network server to a remote network server includes a primary data transfer unit and a remote data transfer unit which are connectable with one another by a conventional communication link. The primary data transfer unit sends mirrored data from the primary network server over the link to the remote data transfer unit which is located a safe distance away. Each data transfer unit includes a server interface and a link interface. The server interface is viewed by the network operating system as another disk drive controller. The link interface includes four interconnected parallel processors which perform read and write processes in parallel. The link interface also includes a channel service unit which may be tailored to commercial communications links such as T1, E1, or analog telephone lines connected by modems.

Data transmission device, system and method

Abstract: A data transmission device (11; 111,) for use in a system (10) comprising a plurality of such devices is described along with a corresponding method of data transmission. A data signal (at 23) is provided for transmission and a timer apparatus (16, 18; 16, 118, 160) establishes a sequence of maximum time intervals (6 hours; 6 hours and 20 seconds) during which the data signal can be transmitted. A transmitter (18, 24, 25; 118, 24, 25) transmits the data signal during each of these maximum time intervals. The timer apparatus (16, 18; 16, 118, 160) generates a random number (steps 33, 54; steps 172, 195) for each one of the maximum time intervals, and the transmitter (18, 24, 25; 118, 24, 25) determines the transmission times for the data signal in accordance with the random numbers provided for each of these maximum time intervals. Preferably, the data transmission devices are part of a data transmission system (10) which includes a data receiver (12), and the data signal is obtained from and corresponds to the output of a utility meter (13). By utilization of random numbers to randomize the transmit times of the transmission devices, the probability that data transmissions from one transmission device will interfere with data transmissions from another device is substantially minimized.

The orthogonal-random waveform dichotomy for digital mobile personal communication

Abstract: The conversion of terrestrial wireless telephony to digital transmission technology is just beginning. However, with more than four years of experimental laboratory and field testing, one has already learned numerous practical lessons, both positive and negative, relative to the art and science of multiple-access communication by large user populations. Europe, Japan, and North America have each developed digital cellular standards. The North American experience has been the most contentious and diverse. Only here have two alternative and rival approaches been carried through to the development of detailed standards leading to imminent large-scale commercial deployments. In this article, the two alternatives are denoted as orthogonal and random waveform multiple access, and are described and discussed successively. >

Optical time division multiplexing: systems and networks

Abstract: The recent advances in optical time division multiplexed (OTDM) systems and components research show the technique to be highly suited to the generation and transmission of high capacity data on a single optical carrier. This approach uses a single wavelength to carry capacities of at least 40 Gb/s. Such systems are based on a clock frequency and tributary data rates which are easily accessible using electronic components. Short optical pulses are used in a return-to-zero data transmission format with temporal interleaving to map a number of optical data channels into a single electronic clock cycle. It is an approach that can be used to achieve extremely high data-rate bit interleaved systems. This article summarizes the developments in this field and outlines a possible methodology to evolve transport networks to encompass the potential that both WDM and OTDM have to offer. >

Modem to support multiple site call conferenced data communications

Abstract: Establishing on-line communication between multiple client computers in a computer network by assigning each client computer a different modulation band for outgoing signal transmission. Each client computer has a modem and client software for operating the modem and otherwise managing communication between the client computer and other client computers. When an on-line session is to be established between the any group of client computers, three or more modulation bands are made available to the client computers. One of the modulation bands is selected for each of the client computers as a modulation band for data transmission, with each client computer having a unique modulation band for data transmission. Each of the client computers utilizes the remaining modulation bands as potential receiving bands. During the on-line communication session, each client computer transmits data using the unique modulation band assigned thereto and receives incoming data using any of the remaining modulation bands. These bandwidth allocation techniques enable simultaneously data transmission between the client computers and, in one implementation, can be used to support video games that are played among remote players.

In-band/out-of-band data transmission method and apparatus for a television system

Abstract: Data transmission for a cable television system includes transmitting data via a plurality of signals including, but not limited to, in-band audio, in-band video, and out-of-band signals. The in-band data signals are transmitted on scrambled or non-scrambled channels. In-band video data transmission further includes selecting certain lines of the vertical blanking interval for in-band video data transmission, omitting certain equalizing pulses during the selected lines and inserting in-band video data during the selected lines. The several data signals, in-band and out-of-band, have compatible transaction formats to facilitate decoding and data storage processes at a subscriber terminal of the cable television system. A data transmission apparatus includes a data inserter for inserting in-band data in non-scrambled channels, an addressable data transmitter for transmitting out-of-band data and a scrambler for inserting data in scrambled channels.

Separating data and control transfer in distributed operating systems

Abstract: Advances in processor architecture and technology have resulted in workstations in the 100+ MIPS range. As well, newer local-area networks such as ATM promise a ten- to hundred-fold increase in throughput, much reduced latency, greater scalability, and greatly increased reliability, when compared to current LANs such as Ethernet.We believe that these new network and processor technologies will permit tighter coupling of distributed systems at the hardware level, and that distributed systems software should be designed to benefit from that tighter coupling. In this paper, we propose an alternative way of structuring distributed systems that takes advantage of a communication model based on remote network access (reads and writes) to protected memory segments.A key feature of the new structure, directly supported by the communication model, is the separation of data transfer and control transfer. This is in contrast to the structure of traditional distributed systems, which are typically organized using message passing or remote procedure call (RPC). In RPC-style systems, data and control are inextricably linked—all RPCs must transfer both data and control, even if the control transfer is unnecessary.We have implemented our model on DECstation hardware connected by an ATM network. We demonstrate how separating data transfer and control transfer can eliminate unnecessary control transfers and facilitate tighter coupling of the client and server. This has the potential to increase performance and reduce server load, which supports scaling in the face of an increasing number of clients. For example, for a small set of file server operations, our analysis shows a 50% decrease in server load when we switched from a communications mechanism requiring both control transfer and data transfer, to an alternative structure based on pure data transfer.

Simultaneous analog and digital communication applications

Abstract: A number of arrangements and methods that achieve concurrent communication of analog information and digital information. In general terms, when the communication channel is viewed as a multi-dimensional space, the digital information signal is divided into symbols, and the symbols are mapped onto the signal space with a preset distance between them. The analog signal, generally limited in magnitude to less than half the distance separating the symbols, is converted to component signals and added (i.e., vector addition) to the symbols. The sum signal is then transmitted to the receiver where the symbols are detected and subtracted from the received signal to yield the analog signal components. The transmitted analog signal is recreated from those components. Arrangements utilizing the above principles are applications where systems that include a digital port can benefit from an analog communication channel, and conversely, where systems that include an analog port can benefit from a digital communication channel.

Closed-loop control of systems over a communication network with queues

Abstract: Due to remote sensor, actuator and processor locations, many systems need to implement closed loop control through a communication network. Thus, they face the problem of random delays being introduced by the network. These delays may deteriorate the system performance and may even cause instability. The problems get more complicated when the possibility of queue formation at the transmitting side is considered for closed loop data transmission. The authors propose a state prediction/control scheme to control this type of system. The scheme utilizes knowledge of the amount of data in a queue to enhance prediction. Two automotive examples are used to illustrate the performance of the proposed scheme.

System and method for communicating with digital and analog devices via a single digital interface

Abstract: The invention is an ISDN terminal equipment which will maintain connectivity with existing analog modems by setting up a voice-grade connection to existing analog modems and using the power of a digital signal Processor DSP to generate the digital equivalent of the analog modem signals for transmission on an ISDN "B" channel.

Efficient algorithms for all-to-all communications in multi-port message-passing systems

Abstract: We present efficient algorithms for two all-to-all communication operations in message-passing systems: index (or all-to-all personalized communication) and concatenation (or all-to-all broadcast) We assume a model of a fully-connected message-passing system, in which the performance of any point-to-point communication is independent of the sender-receiver pair We also assume that each processor has k ≥ 1 ports, through which it can send and receive k messages in every communication round The complexity measures we use are independent of the particular system topology and are based on the communication start-up time and on the communication bandwidthIn the index operation among n processors, initially, each processor has n blocks of data, and the goal is to exchange the i-th block of processor j with the j-th block of processor i We present a class of index algorithms that is designed for all values of n and that features a trade-off between the communication of start-up time and the data transfer time This class of algorithms includes two special cases: an algorithm that is optimal with respect to the measure of the start-up time, and an algorithm that is optimal with respect to the measure of the data transfer time We also present experimental results featuring the performance tuneability of our index algorithms on the IBM SP-1 parallel systemIn the concatenation operation among n processors, initially, each processor has one block of data, and the goal is to concatenate the n blocks of data from the n processors and to make the concatenation result known to all the processors We present a concatenation algorithm that is optimal, for most values of n, in the number of communication rounds and in the amount of data transferred

Method and apparatus for testing a digital communication channel

Abstract: A system and method for testing signal transmission quality within a digital communication system is disclosed herein The system may be incorporated within a digital cellular communication system in which information is exchanged over spread spectrum communication channels, among a plurality of mobile users, via at least one cell-site The system contemplates testing a digital communication channel by transmitting a test sequence of digital data over the communication channel The test sequence of digital data transmitted over the communication channel is received at a receiving station, within which is also generated a replica of the test sequence of digital data The accuracy of transmission over the communication channel is then determined by comparing the replica of the test sequence of digital data to the test sequence of data received over the communication channel The system allows the test sequence of digital data to be transmitted at one of a set of known data rates, with the receive station being disposed to identify the data rate associated with each test sequence of digital data In a preferred implementation transmission of the test sequence involves generating a first plurality of data packets, which collectively comprise the test sequence of digital data Each data packet is assigned one of a multiplicity of data rates in accordance with a first pseudorandom process, and is then transmitted at the data rate assigned thereto

System and method for exchanging computer data processing capabilities

Abstract: A system and method for exchanging data processing capabilities between computers. The computers exchange capabilities so that data transfer between the computers may be made in the most efficient data format possible for the two computers. A first computer, which will receive a data file, sends a list of data processing capabilities to a second computer, which will transmit the data file to the first computer. The transmitting computer examines the capabilities list of the receiving computer as well as its own capabilities list and determines the most efficient data format for the transfer. The transmitting computer may process the data file into an intermediate format for efficient data transfer so that the receiving computer will process the intermediate data file into the desired data format. The capabilities list can be cached for future communication between the computers. The system can update the capabilities list and inform other computers whether their cached capabilities list is current. Capabilities can also be forwarded from one computer to another so that a third computer can determine the capabilities of the first computer from the second computer or the capabilities of the second computer from the first computer. The system is readily applicable to facsimile machines where custom and application data processing capabilities can be exchanged.

Capacities of equivalent channels in multilevel coding schemes

Abstract: The channel capacity of an M-ary digital transmission scheme M > 2 can in principle be achieved by multilevel codes together with multistage decoding, if the rates of the component codes are equal to the capacities of the equivalent channels for each coding level.

Automated data card payment verification method

Abstract: A method of data transmission over existing telephone lines and later verification of that transmission includes electronic payment verification using telephone transmission of payment information and return transmission of a unique card account number, storage of the information and account number on a database and a data card through a data storage device, and verification of the infomation and account number at a later time by a separate data storage device and the same database.

200-Mb/s/ch 100-m optical subsystem interconnections using 8-channel 1.3-/spl mu/m laser diode arrays and single-mode fiber arrays

Abstract: Synchronous parallel optical-fiber transmission is an attractive method for providing increased interconnection throughput and higher density in advanced information systems. Skew suppression (reducing transmission delay time variation), error-free fully DC-coupled data transmission capability, compactness, and low power consumption of modules are important requirements. In order to meet these requirements, we developed optical subsystem interconnections using long-wavelength laser diode arrays and single-mode fiber arrays. The major design criteria are discussed, especially as they are related to skew due to laser diode turn-on delay and receiver input optical power variation. The use of low-threshold-current laser diode arrays is an important design requirement. Based on the design criteria discussed in this work, we demonstrated and channel 200-Mb/s/ch 100-m transmission using compact (0.18 cc/ch/module), low power (total 280 mW/ch), fully integrated transmitter and receiver modules with an ECL (emitter coupled logic) interface. These modules include our new laser diode arrays with low threshold current of 3.2 mA. Performance results showed that these modules are very effective as interconnections between synchronously operating subsystems. >

System for executing high speed communication protocol processing by predicting protocol header of next frame utilizing successive analysis of protocol header until successful header retrieval

Abstract: Communication control equipment for connecting a computer system to a network and supporting the computer system to set a plurality of connections on the network and perform parallel communication between computers. The communication control equipment includes an interface circuit for the computer system, a microprocessor for performing communication control processing, a local memory for storing programs and work data, a buffer memory for temporarily storing transmission and reception data, a DMA transfer unit for performing data transfer between a memory in the computer system and the buffer memory and protocol header transfer between the buffer memory and the local memory, a network controller for controlling transmission and reception of data to the network, and a header retrieval unit for predicting a protocol header of a frame to be next received in correspondence to each of a plurality of connections and retrieving a header corresponding to a protocol header of a received frame transferred by the DMA transfer unit.

Wireless communication system and wireless terminal device using fixed length communication frame

Abstract: A wireless communication system includes a plurality of wireless terminals and a base station for periodically generating a fixed-length communication frame composed of an information field which includes a plurality of information slots, and first and second control fields which are arranged preceding the information field and each of which includes a plurality of time slots. Each time slot of the first control field of each communication frame is used for allowing the base station to send control data for designating a terminal which is to make the transmission or reception of data in one information slot of the information field, and each time slot of the second control field thereof is used for allowing one wireless terminal to send control data indicating a requirement for assignment of an information slot for data transmission. Each wireless terminal, when receiving control data inclusive of an address of that terminal in the i-th time slot of the first control field of each communication frame, makes the reception or transmission of data in the i-th information slot in the information field of that communication frame. When the control data is not found out in the first control field, the power source of a reception unit of the wireless terminal is turned off during a period of time until the next communication frame is generated.

Telemedicine using mobile satellite communication

Abstract: With a view to providing paramedical care within moving vehicles, a telemedicine technique using mobile satellite communication was proposed. With this technique, the diagnosis from a specialist and the emergency care under his/her instructions would be available on the spot without unnecessary delay. The characteristic problems of this technique were identified as: channel capacity, size of the system, reliability of vital sign transmission, real-time operation and electromagnetic interference. Measures against these problems were devised, and their effectiveness was analyzed. A data format was designed and an experimental system was developed. The system can simultaneously transmit a color image, an audio signal, 3 channels ECG and blood pressures from a mobile station to a ground station. It can transmit an audio signal and error control signals from a ground station to a mobile station in a full duplex mode. Fundamental transmission characteristics were measured in a fixed station. Finally, experiments of medical data transmission were conducted with a navigating ship and an aircraft flying an international route. The measured threshold values of C/N/sub o/ to guarantee satisfactory data reception were well below the lower boundary of C/N/sub o/ of the communication link. Consequently, the feasibility of this technique was verified. >

A low power transponder IC for high performance identification systems

Abstract: A novel integrated circuit for a battery-less transponder system is presented. Battery-less transponders require contactless transmission of both the information and power between a mobile data carrier and a stationary or handheld reader unit. The operating principle of this system gives a superior performance in reading distance due to separation of the powering and data transmission phases. This paper describes the function of the transponder IC and the circuit design techniques used for the various building blocks. >