Showing papers on "Signal published in 1997"

Microring resonator channel dropping filters

Abstract: Microring resonators side coupled to signal waveguides provide compact, narrow band, and large free spectral range optical channel dropping filters. Higher order filters with improved passband characteristics and larger out-of-band signal rejection are realized through the coupling of multiple rings. The analysis of these devices is approached by the novel method of coupling of modes in time. The response of filters comprised of an arbitrarily large dumber of resonators may be written down by inspection, as a continued fraction. This approach simplifies both the analysis and filter synthesis aspects of these devices.

Digital Signal Processing : A Computer-Based Approach

Abstract: From the Publisher: "Digital Signal Processing: A Computer-Based Approach" is intended for a two-semester course on digital signal processing for seniors or first-year graduate students. Based on user feedback,a number of new topics have been added to the second edition,while some excess topics from the first edition have been removed. The author has taken great care to organize the chapters more logically by reordering the sections within chapters. More worked-out examples have also been included. The book contains more than 500 problems and 150 MATLAB exercises. New topics in the second edition include: finite-dimensional discrete-time systems,correlation of signals,inverse systems,system identification,matched filter,design of analog and IIR digital highpass,bandpass and bandstop filters,more on FIR filters,spectral analysis of random signals and sparse antenna array design.

Transaction security apparatus and method

Abstract: A transaction security apparatus which comprises a transaction device, wherein the transaction device one of generates and transmits a first signal in response to a transaction, and a communication device associated with an individual account. The communication device receives the first signal. The communication device generates a second signal which provides a notification to the individual account holder of the transaction. The transaction device transmits the first signal to the communication device. The first signal is transmitted over a communication network directly to the communication device.

Signal-space projection method for separating MEG or EEG into components.

Abstract: CURRENTS INSIDE a conducting body can be estimated by measuring the magnetic and/or the electric field at multiple locations outside and then constructing a solution to the inverse problem, i.e. determining a current configuration that could have produced the measured field. Unfortunately, there is no unique solution to this problem (HELMHOLTZ, 1853) unless restricting assumptions are made. The minimum-norm estimate (HAM/~.L,~INEN and ILMONIEMI, 1994) provides a solution with the smallest expected overall error when minimum a priori information about the source distribution is available. Other methods to estimate a continuous current distribution producing the measured signals have been studied (PASCUAL-MARQUI et al., 1994; WANG et aL, 1995; GORODNITSKY, et al., 1995). A different approach is to divide the brain activity into discrete components such as current dipoles (ScHERG, 1990; MOSHER et al., 1992). Here we widen this approach into arbitrary current configurations. In our signal-space projection (SSP) method, the signals measured by d sensors are considered to form a time-varying vector in a d-dimensional signal space. The component vectors,, i.e. the signals caused by the different neuronal sources, have different and fixed orientations in the signal space. In other words, each source has a distinct and stable field pattern. All the current eonfi~marations producing the same measured field pattern are indistinguishable on the basis of the field: they have the same vector direction in the signal space and thus belong to the same equivalence class of current configurations (TESCHE et al., 1995a). The angle in the signal space between vectors representing different equivalence classes, e.g. between component vectors, is a measure of similarity of the equivalence classes in signal space and a way to characterise the separability of sources. The cosine of this angle has previously been used as a numerical charaeterisation of the difference between topographical distributions (DESMEDT and CHALK[.IN, 1989). If the direction of at least one of the component vectors forming the measured multi-channel signal can be determined from the data, or is known otherwise, SSP can be used to simplify subsequent analysis. For example, if an early deflection in an evoked response is produced by one source, and the rest of the response is a mixture of signals from this and other sources, SSP can separate the data into two parts so that the early source contributes only to one part. In general, the signals are divided into two orthogonal parts: s~, including the time-varying contribution from sources with known signalspace directions; and s~_, including the rest of the signals. Both sl~ and s j_ can then be analysed separately in more detail. By analysing s t , we can detect activity originally masked by s~. On the other hand, the sources included in stl are seen with an enhanced signal-to-noise ratio. By forward modelling of sources in selected patches of cortex, it is possible to form a spatial filter that selectively passes only the signals that may have been generated by currents in the given patches. If the subspace defined by artefacts can be determined, the artefactflee S L can be analysed. In SSP, in contrast to PCA (HARRIS, 1975; MAIER et al., 1987) and other analysis methods (GRUMMICH et al., 1991; KOLES et aL, 1990; KOLES, 1991; SOONG and KOLES, 1995; BESA*), the source decomposition does not depend on the orthogonality of source components or the availability of source or conductivity models. No conductivity or source models are needed if the component vectors are estimated directly from the measured signals. This is useful when no source estimation is needed, e.g. when artefacts or somatomotor activity in a cogrritive study must be filtered out. The angles between the components provide an easy and illustrative way to characterise the linear dependence between the components and thus the separability of sources. The concept of signal space in MEG was introduced previously ([LMONIEMI, 1981; [LMONIEMI and WILLIAMSON,

Steering angle determaination method and apparatus

Abstract: In a vehicle with a hand wheel, steerable wheels positionally responsive to the hand wheel and a steering position sensor coupled to the handwheel and providing a handwheel angle signal indicative of an angular position of the handwheel, a steering angle determination method comprising the steps of: first filtering the handwheel angle signal to provide a first filter output; defining a comparison window around the first filter output; comparing the handwheel angle signal to the comparison window; when the handwheel angle signal is within the comparison window, second filtering the handwheel angle signal to provide a second filter output; when the handwheel angle signal is not within the comparison window, maintaining the second filter output fixed; and determining a steer angle signal as the difference between the handwheel angle signal and the second filter output, wherein offsets between the handwheel angle signal and steered positions of the steerable wheels are compensated for.

Seismic attenuation tomography using the frequency shift method

Abstract: We present a method for estimating seismic attenuation based on frequency shift data. In most natural materials, seismic attenuation increases with frequency. The high-frequency components of the seismic signal are attenuated more rapidly than the low-frequency components as waves propagate. As a result, the centroid of the signal's spectrum experiences a downshift during propagation. Under the assumption of a frequency-independent Q model, this downshift is proportional to a path integral through the attenuation distribution and can be used as observed data to reconstruct the attenuation distribution tomographically. The frequency shift method is applicable in any seismic survey geometry where the signal bandwidth is broad enough and the attenuation is high enough to cause noticeable losses of high frequencies during propagation. In comparison to some other methods of estimating attenuation, our frequency shift method is relatively insensitive to geometric spreading, reflection and transmission effects, source and receiver coupling and radiation patterns, and instrument responses. Tests of crosswell attenuation tomography on 1-D and 2-D geological structures are presented.

Ultrawide-band communication system and method

Abstract: An impulse radio communications system using one or more subcarriers to communicate information from an impulse radio transmitter to an impulse radio receiver. The impulse radio communication system is an ultrawide-band time domain system. The use of subcarriers provides impulse radio transmissions added channelization, smoothing and fidelity. Subcarriers of different frequencies or waveforms can be used to add channelization of impulse radio signals. Thus, an impulse radio link can communicate many independent channels simultaneously by employing different subcarriers for each channel. The impulse radio uses modulated subcarrier(s) for time positioning a periodic timing signal or a coded timing signal. Alternatively, the coded timing signal can be summed or mixed with the modulated subcarrier(s) and the resultant signal is used to time modulate the periodic timing signal. Direct digital modulation of data is another form of subcarrier modulation for impulse radio signals. Direct digital modulation can be used alone to time modulate the periodic timing signal or the direct digitally modulated the periodic timing signal can be further modulated with one or more modulated subcarrier signals. Linearization of a time modulator permits the impulse radio transmitter and receiver to generate time delays having the necessary accuracy for impulse radio communications.

Acoustic monitoring system

Abstract: This invention is a transducer (14) in communication with fluid in a pad (12), held in close contact against a sound or movement (19) source which monitors acoustic signals transferred into the fluid (62). The signal pattern is monitored aurally and/or compared to predetermined reference patterns, and optional control and stimulation means can be activated in response to the comparison results. The sensed acoustic signal can be transmitted to a remote receiver or processed locally. Typically, the acoustic signal is representative of the heartbeat or breathing of a living organism. The monitoring system may be applied to diverse situations including SIDS, apnea, home baby monitoring, medical transport devices, blood pressure cuffs, seats, combat casualty care and hand-held devices.

Information record medium, apparatus for recording the same and apparatus for reproducing the same

Abstract: An information recording apparatus (SS1) is provided with: a signal process device (72) for dividing record information (R) to be recorded into a plurality of partial record informations including at least video information, for applying a predetermined signal process to each of the partial record informations to thereby output processed partial record information (Sr, 42, 43, 44), and for generating and outputting, on the basis of control information (Si) which is inputted from the external to control a reproduction of the record information, additional information (Sac, 64: PGCI) including still time information (66E) indicative of a time for performing a still picture reproduction of a final picture of each of the partial record informations which is a picture included in each of the partial record informations at a final portion thereof after reproducing each of the partial record informations, at a time of reproducing the record information, the still time information being set for each of the partial record informations; a multiplex device (75, 76) for multiplexing the processed partial record information and the additional information to thereby generate multiplexed processed record information (Sap); and a record device (77, 78) for recording the multiplexed processed record information onto an information record medium (1: DVD).

Extended ICA Removes Artifacts from Electroencephalographic Recordings

Abstract: Severe contamination of electroencephalographic (EEG) activity by eye movements, blinks, muscle, heart and line noise is a serious problem for EEG interpretation and analysis. Rejecting contaminated EEG segments results in a considerable loss of information and may be impractical for clinical data. Many methods have been proposed to remove eye movement and blink artifacts from EEG recordings. Often regression in the time or frequency domain is performed on simultaneous EEG and electrooculographic (EOG) recordings to derive parameters characterizing the appearance and spread of EOG artifacts in the EEG channels. However, EOG records also contain brain signals [1, 2], so regressing out EOG activity inevitably involves subtracting a portion of the relevant EEG signal from each recording as well. Regression cannot be used to remove muscle noise or line noise, since these have no reference channels. Here, we propose a new and generally applicable method for removing a wide variety of artifacts from EEG records. The method is based on an extended version of a previous Independent Component Analysis (ICA) algorithm [3, 4] for performing blind source separation on linear mixtures of independent source signals with either sub-Gaussian or super-Gaussian distributions. Our results show that ICA can effectively detect, separate and remove activity in EEG records from a wide variety of artifactual sources, with results comparing favorably to those obtained using regression-based methods.

Differential touch sensor and control circuit therefor

Abstract: A differential touch sensor apparatus for detecting the presence of an object such as a human appendage, the apparatus having a first electrode, a second electrode positioned proximate to the first electrode, a differential circuit connected to the first and second electrodes, and a pulse or other signal source connected to provide electrical signals that generate an electric field between the first and second electrodes. Introduction of an object near the first electrode affects the electric field between the first and second electrodes, thereby affecting the voltage difference between them. A differential circuit provides an output signal responsive to the difference in voltage between the first and second electrodes. In an alternative embodiment, a strobe electrode is provided proximate to both said first and second electrodes and the pulses or other signals are provided to the strobe electrode to induce an electric field between the strobe electrode and each of the first and second electrodes.

Article tracking system

Abstract: System for tracking mobile tags. Cell controllers with multiple antenna modules generate a carrier signal which is received by the tags. Tags shift the frequency of the carrier signal, modulate an identification code onto it, and transmit the resulting tag signal at randomized intervals. The antennas receive and process the response, and determine the presence of the tags by proximity and triangulation. Distance of a tag from an antenna is calculated by measuring the round trip signal time. The cell controllers send data from the antenna to a host computer. The host computer collects the data and resolves them into positional estimates. Data are archived in a data warehouse, such as an SQL Server.

Sensorless field orientation control of an induction machine by high frequency signal injection

Abstract: This paper describes a new scheme to find the rotor flux angle from stator voltages and currents by injecting a high-frequency signal. The signal is not a rotating one but a fluctuating one at a reference frame rotating synchronously to the fundamental stator frequency. When the estimated rotor flux angle coincides with the actual angle, the proposed method makes virtually no ripple torque, no vibration and less audible noise caused by the injected signal. The difference of impedances between the flux axis and the quadrature axis at high-frequency signal injection on the rotor flux angle is explained by the equivalent circuit equation of the induction machine. The difference is verified by experiments on test motors under various testing conditions. A sensorless field orientation algorithm is proposed and experimental results clarify the satisfactory operation of the algorithm with one hundred and fifty percent load torque at zero stator frequency.

Rapid non-invasive blood pressure measuring device

Abstract: A measurement device for generating an arterial volume-indicative signal includes an exciter and a detector. The exciter is adapted to receive an oscillating signal and generate a pressure wave based at least in part on the oscillating signal on the artery at a measurement site on a patient. The pressure wave includes a frequency. The detector is placed sufficiently near the measurement site to detect a volumetric signal indicative of arterial volume of the patient.

Internet enhanced video system

Abstract: A system for accessing the Internet based on an Internet information pointer encoded in a video signal. The system includes a video display adapted to display a video portion of the video signal. The system also includes an Internet access device including a decoder adapted to extract the Internet information pointer encoded in the video signal, the access device being adapted to connect to the Internet to access the Internet based on the extracted Internet information pointer.

Speech intelligibility as a function of the number of channels of stimulation for signal processors using sine-wave and noise-band outputs

Abstract: Vowels, consonants, and sentences were processed through software emulations of cochlear-implant signal processors with 2-9 output channels. The signals were then presented, as either the sum of sine waves at the center of the channels or as the sum of noise bands the width of the channels, to normal-hearing listeners for identification. The results indicate, as previous investigations have suggested, that high levels of speech understanding can be obtained using signal processors with a small number of channels. The number of channels needed for high levels of performance varied with the nature of the test material. For the most difficult material--vowels produced by men, women, and girls--no statistically significant differences in performance were observed when the number of channels was increased beyond 8. For the least difficult material--sentences--no statistically significant differences in performance were observed when the number of channels was increased beyond 5. The nature of the output signal, noise bands or sine waves, made only a small difference in performance. The mechanism mediating the high levels of speech recognition achieved with only few channels of stimulation may be the same one that mediates the recognition of signals produced by speakers with a high fundamental frequency, i.e., the levels of adjacent channels are used to determine the frequency of the input signal. The results of an experiment in which frequency information was altered but temporal information was not altered indicates that vowel recognition is based on information in the frequency domain even when the number of channels of stimulation is small.

System for interactively distributing information services

Abstract: An interactive information distribution system (100) includes service provider equipment for generating an information stream that is coupled to an information channel and transmitted to subscriber equipment (124). The service provider also generates a command signal that is coupled to a command channel and transmitted to the subscriber equipment (124). The service provider also receives information manipulation requests from the subscriber via a back channel (109). A communication network (110) supporting the information channel, command channel and back channel is coupled between the service provider equipment and the subscriber equipment (124).

Active pulse blood constituent monitoring method

Abstract: A monitoring method is disclosed which provides for inducing an active pulse in a blood volume of a patient. The induction of an active pulse results in a cyclic, and periodic change in the flow of blood through a fleshy medium under test. By actively inducing a change of the blood volume, modulation of the volume of blood can be obtained to provide a greater signal to noise ratio. This allows for the detection of constituents in blood at concentration levels below those previously detectable in a non-invasive system. Radiation which passes through the fleshy medium is detected by a detector which generates a signal indicative of the intensity of the detected radiation. Signal processing is performed on the electrical signal to isolate those optical characteristics of the electrical signal due to the optical characteristics of the blood.

Integrated electronic tag reader and wireless communication link

Abstract: A method and apparatus for object identification comprising a portable electronic tag reader (50) having a transceiver capable of reading data from electronic tags (18) and transmitting data to base unit (232). The same transceiver (204) is utilized to receive information from the base unit and write data to tags (18). The invention further comprises a transceiver for generating a modulated or unmodulated signal, and a receiver (204) and signal processor for processing the return signal. The interrogation signal is modulated by the identification data and transmitted to a base unit through a wireless local area network (242). A demodulator within portable unit (50) extracts information received from base unit (232), for local processing, or transfer to tag (18). In one embodiment, the portable electronic tag reader (50) includes a user interface for initiating commands and displaying status information associated with the reading, downloading, or uploading processes.

In-band on-channel digital broadcasting method and system

Abstract: A method and system are provided for the transmission and reception of an In-band On-channel (IBOC) FM-band digital audio broadcast (DAB) signal. The IBOC DAB signal (63) is generated in the transmitter (47, 49) to occupy the upper and lower sideband frequency regions (11, 13) in the RF emission mask for the conventional broadcast analog FM-band. Redundant source bit information is transmitted in upper and lower sidebands so that the loss of information in either one but not both sidebands due to large amount of interference or distortion does not deleteriously affect the IBOC DAB receiver performance. The system exhibits frequency-diversity and time-diversity. The receiver (231, 233) determines which codeword bit estimate of upper or lower sideband signal is less erroneous. The receiver system selects between decoded estimates for each pair of demodulated ECC codewords or combines both ECC codeword estimates prior to decoding in certain embodiments.

Net analyte signal calculation in multivariate calibration

Abstract: Net analyte signal plays an important role in the calculation of figures of merit for characterizing a calibration model. Until now, its computation has only been feasible for the direct calibration model, which requires knowledge of pure spectra or concentrations of all contributing species in the calibration samples. An increasingly important calibration model is the inverse calibration model, which also allows for quantitation if the knowledge about the interferents is incomplete. This paper shows that net analyte signal computation is possible for the inverse calibration case. Application to the determination of protein content in wheat samples by near-infrared spectrometry is presented. Net analyte signal calculation was used to estimate selectivities (ratio of signal available for quantitation to the total measured signal). The selectivities were found to range between 0 and 2% of the measured reflectance signal. A new measure for outlier diagnosis based on the correlation of the net analyte signal ...

Methods and apparatus for selectively reproducing segments of broadcast programming

Abstract: Systems and methods for editing broadcast programming signals which allow a user to compile a proprietary signal tailored to the user's individual preferences are provided. Systems of the present invention include a receiver for receiving a broadcast programming signal in any broadcast format, a database memory having identification signals stored therein, a comparator for comparing portions of the broadcast signal with the identification signal in order to select those portions of the broadcast programming signal to be recorded, a data processor, and a compression buffer for storage of the selected broadcast programming signals. Methods of the present invention include receiving a broadcast programming signal, comparing the broadcast programming signal to an identification signal derived, employing a signal analyzer originally to derive the identification signals from the content of the broadcast programming before broadcast, so as to select a portion of the broadcast programming signal, and storing the selected portion in a memory.

Theory and application of static field inhomogeneity effects in gradient‐echo imaging

Abstract: The influence of local static magnetic field inhomogeneities on gradient-echo imaging is discussed and the underlying theoretical aspects are reviewed. A high-resolution approach is suggested to suppress image distortion and restore signal loss due to spin dephasing. Acquisition of three-dimensional data sets not only overcomes part of the limitations associated with gradient echoes but also makes it possible to extract local information about the strength or direction of background gradients and relative susceptibility changes between different tissues. Applications of the suggested approach in the human brain for anatomical imaging as well as for extraction of physical and physiological parameters are presented and discussed.

Dual mode transmitter-receiver and decoder for RF transponder tags

Abstract: An enhanced backscatter RF-ID tag reader system and multiprotocol RF tag reader system is provided. In a multiprotocol mode, the system emits a non-stationary interrogation signal, and decodes a phase modulated backscatter signal by detecting a stronger phase component from quadrature phase representations or determining phase transition edges in a phase of a received signal. The RF tag reader system predicts or follows the phase of the backscatter signal, thereby avoiding interference from nulls in the received signal waveform due to the non-stationary interrogation signal, relative movement or environmental effects. An acoustic RF-ID tag detection system detects the reradiated signal corresponding to respective transformation of a signal in the tag. Detection of either type of RF-ID tags therefore is possible, and the absence of any tag or absence of any valid tag also determined.

A high data rate communications network employing an adaptive sectored antenna

Abstract: A high data rate communication system (12) that employs an adaptive sectored antenna (46) is disclosed. The high data rate communication system (12) includes an antenna subsystem (28) for receiving and transmitting data. The antenna subsystem (28) is adapted to be spatially steered. A radio frequency transceiver (32) that is coupled to the antenna subsystem (28) and that selectively generates a bit error rate (BER) signal (206) and a receive signal strength indication (RSSI) signal (210) based upon a received antenna training sequence is also provided. The system (12) also includes a beam steering state machine (200) that is coupled to the radio frequency transceiver (32) and that selectively generates a BER_PASS signal (207) and an RSSI_PASS signal (209) based upon whether the BER signal (206) is in a first logical relationship with a predetermined BER signal and the RSSI signal (210) is in a second logical relationship with a predetermined RSSI signal. An antenna controller (38) is coupled to the antenna subsystem (28) and the beam steering state machine (200) and selectively generates antenna control signals (220) to spatially steer the antenna subsystem (28) based upon the BER_PASS signal (207) and the RSSI_PASS signal (209).

Semiconductor chip package

Abstract: The semiconductor package comprises a chip 21 having a bonding pad formed at the center portion thereof; and a substrate 22 for mounting the chip 21 thereon, which has a slot formed at the center portion thereof and is formed with a signal circuit pattern on, at least, one surface thereof. An adhesive tape 23 is inserted between the chip 21 and the substrate 22 for attaching and fixing the chip 21 to the upper surface of the substrate 22 so that the bonding pad of the chip 21 is above the slot. Bonding wires 24 connect the chip to the circuit pattern on the substrate.

Devices for transmitter path weights and methods therefor

Abstract: A receiving communication device (101) receives a reference signal transmitted through at least one of the antennas (106, 110, 112) of an antenna array of a transmitting communication device (102). The receiving communication device determines a weight to be associated with the at least one of the antennas, and transmits weight information to the transmitting communication device. The transmitting communication device adjusts the weight associated with the at least one of the antennas according to weight information received from the receiving communication device.

One-Channel Time Reversal of Elastic Waves in a Chaotic 2D-Silicon Cavity

Abstract: Acoustic time-reversal experiments usually need large arrays of transducers. It is shown that in a reflecting cavity with negligible absorption one is able to perform a time reversal of elastic waves using a single element. The field is measured at one point over a long period of time and the time-reversed signal is reinjected at the same position. Numerical simulations illustrate the process. Experiments carried out in silicon wafers show that it is possible to obtain an excellent temporal and spatial focusing quality.