Showing papers on "Signal published in 1986"

Functional architecture of cortex revealed by optical imaging of intrinsic signals

Abstract: Optical imaging of cortical activity offers several advantages over conventional electrophysiological and anatomical techniques. One can map a relatively large region, obtain successive maps to different stimuli in the same cortical area and follow variations in response over time. In the intact mammalian brain this imaging has been accomplished with the aid of voltage sensitive dyes. However, it has been known for many years that some intrinsic changes in the optical properties of the tissue are dependent on electrical or metabolic activity. Here we show that these changes can be used to study the functional architecture of cortex. Optical maps of whisker barrels in the rat and the orientation columns in the cat visual cortex, obtained by reflection measurements of the intrinsic signal, were confirmed with voltage sensitive dyes or by electrophysiological recordings. In addition, we describe an intrinsic signal originating from small arteries which can be used to investigate the communication between local neuronal activity and the microvasculature. One advantage of the method is that it is non-invasive and does not require dyes, a clear benefit for clinical applications.

Ultrasonic testing of materials

Abstract: An ultrasonic apparatus for testing a material comprises an oscillator (10) which generates a selected frequency in the ultrasonic range. A transducer (1) is connected to the oscillator (10) for applying an ultrasonic signal to the material and for receiving an echo signal back from the material. A phase detector (5) receives the echo signal and an in-phase oscillator signal to generate a first display signal, and a phase detector (6) receives a quadrature signal (90° out of phase from the oscillator signal) and the echo signal to generate a second display signal. The first and second display signals are utilised in a visual display, such as a cathode ray tube (8), to generate an image. The image changes according to the phase shift between the ultrasonic signal transmitted into the material and the echo signal, which, in turn, can be utilised to determine the presence and depth of a flaw or boundary in the material.

Capillary flow device

Abstract: Methods and devices are provided involving at least one chamber, at least one capillary, and at least one reagent involved in a system providing for a detectable signal. As appropriate, the devices provide for measuring a sample, mixing the sample with reagents, defining a flow path, and reading the result. Of particular interest is the use of combinations of specific binding pair members which result in agglutination information, where the resulting agglutination particles may provide for changes in flow rate, light patterns of a flowing medium, or light absorption or scattering. A fabrication technique particularly suited for forming internal chambers in plastic devices is also described along with various control devices for use with the device.

An Efficient Algorithm for Spectral Analysis of Heart Rate Variability

Abstract: We present a simple efficient algorithm for the derivation of a heart rate signal from the electrocardiogram. We demonstrate that the amplitude spectrum of this heart rate signal more closely matches that of the input signal to an integral pulse frequency modulation (IPFM) model of the heart's pacemaker than do the spectra of other ECG-derived heart rate signals. The applicability of this algorithm in cross-spectral analysis between heart rate and other physiologic signals is also discussed.

Blood flow imaging by cine magnetic resonance.

Abstract: A technique for measuring blood flow by whole body nuclear magnetic resonance is described. This method uses imaging gradient profiles that combine even echo rephasing with a field echo sequence to overcome the problem of signal loss from flowing blood. The flow velocity component in any desired direction may be measured by appropriate gradient profile modifications, producing velocity dependent phase shifts that can be displayed by phase mapping. The sequence allows for fast repetition so that flow information may be acquired rapidly from many points in the cardiac cycle and has been used in this mode to observe and measure blood flow in the heart chambers and great vessels. Flow measurements in the femoral artery were also carried out using the same technique; these were compared with similar measurements obtained by Doppler ultrasound. The technique can readily be applied using standard imaging equipment and should prove useful in the clinical assessment of many diseases of the cardiovascular system.

Experimental realization of a localized one-photon state.

Abstract: In the process of spontaneous parametric down-conversion a signal and an idler photon are created simultaneously. By use of the photoelectric detection of the signal photon as a gate, a good approximation to the ideal localized one-photon state can be achieved. This has been confirmed by direct photon-counting measurements.

Signal processing method and apparatus for producing interpolated chrominance values in a sampled color image signal

Abstract: A signal processing method and apparatus for processing a sampled color image signal of the type having luminance values and chrominance values representing a highly sampled luminance component and less highly sampled chrominance components to produce interpolated chrominance values between sampled chrominance values is characterized by producing hue values at neighboring chrominance component sample locations as a function of a luminance value and the chrominance value at the neighboring locations; producing a signal representing an interpolated hue value as a function of neighboring hue values; and producing a signal representing an interpolated chrominance value as a function of the interpolated hue value and a luminance value at the interpolated location. The signal processing method reduces color fringing in an image reproduced from the sampled image signal without introducing unwanted hue shifts.

Biomedical method and apparatus for controlling the administration of therapy to a patient in response to changes in physiologic demand

Abstract: A biomedical apparatus capable of sensing changes in the heart's ventricular volume or stroke volume and then changing the operating performance of the device in a fashion as a function of stroke volume. A relatively low frequency signal (under 5 KHz) is applied between spaced electrodes disposed in the heart and the beating action of the heart serves to modulate this signal due to changes in impedance being sensed between these or other electrodes within the heart. The modulated carrier signal is then processed to remove R-wave and other electrical artifacts and then demodulated to remove the carrier frequency component leaving the envelope which is proportional to instantaneous ventricular volume. This envelope signal then contains stroke volume and ventricular volume information which can be used by the biomedical apparatus to vary its operating parameters. For example, a current proportional to changes in stroke volume may be injected into the timing circuit of a demand-type cardiac pacer pulse generator whereby the interpulse interval of the pulse generator is varied as a function of stroke volume.

System for evaluation and recording of responses to broadcast transmissions

Abstract: A system for evaluating responses to broadcast programs, such as television programs, includes an instructional signal modulated onto an audio signal transmitted concurrently with the television program. At each of a plurality of remote receiving stations, one or more members of a remote audience has the opportunity to respond to a situation presented in the television program by entering a response on a keyboard. The system includes, at each remote receiving station, a memory responsive to the instructional signal for storing desired responses or response criteria, and a comparison circuit for comparing responses entered at the keyboard with the response criteria stored in the memory. Also provided is electronic circuitry for scoring the responses in accordance with commands from the instructional signal, and a recording device for providing a permanent record of the audience score at each of the remote receiving stations.

Electrical power line and substation monitoring apparatus and systems

Abstract: An electrical power monitoring and control system including individual sensor modules for mounting directly upon energized electrical power conductors and systems employing such modules, with principal emphasis upon the provision of both data transmitting and receiving means in each sensor module and at an associated ground station. The modules sense the instantaneous values of all parameters necessary to perform complete metering functions and, in one embodiment, are synchronized by a signal transmitted from the ground station and received by all modules so that the values are measured simultaneously on all conductors at a substation. The signals are transmitted by the modules in a time-synchronized manner and are in a condition for use directly by the ground station microprocessor. In another embodiment, data transmissions by a plurality of modules is synchronized to avoid data collisions by self-contained means within each module, requiring no synchronizing signal from the ground station. The modules preferably include a reliable battery back-up system, requiring essentially no removal and/or replacement of batteries for recharging, for providing power to the module electronics when there is little or no current flowing through the associated conductor.

Biomedical Signal Processing

Abstract: First published in 1986: The presentation of the material in the book follows the flow of events of the general signal processing system. After the signal has been acquired, some manipulations are applied in order to enhance the relevant information present in the signal. Simple, Optimal, and adaptive filtering are examples of such manipulations. The detection of wavelets is of importance in biomedical signals; they can be detected from the enhanced signal by several methods. The signal very often contains redundancies. When effective storing, transmission, or automatic classification are required, these redundancies have to be extracted.

Adaptive microphone-array system for noise reduction

Abstract: This paper introduces a new adaptive microphone-array system for noise reduction (AMNOR system). It is first shown that there exists a tradeoff relationship between reducing the output noise power and reducing the frequency response degradation of a microphone-array to a desired signal. It is then shown that this tradeoff can be controlled by the introduction of a fictitious desired signal. A new optimization criterion is presented which minimizes the output noise power while maintaining the frequency response degradation below some pre-determined value (AMNOR criterion). AMNOR determines an optimal noise reduction filter based on this criterion by controlling the tradeoff utilizing the fictitious desired signal. Experiments on noise reduction processing were carried out in a room with a 0.4-s reverberation time. The superiority of the AMNOR criterion over conventional LMS and constrained LMS criteria for reducing noise in speech signals was confirmed in subjective preference tests. The AMNOR system improved the SNR by more than 15 dB in the 300-3200 Hz range.

Time-varying filtering and signal estimation using Wigner distribution synthesis techniques

Abstract: The short-time Fourier transform (STFT), the ambiguity function (AF), and the Wigner distribution (WD) are mixed time-frequency signal representations that use Fourier transform techniques to map a one-dimensional function of time into a two-dimensional function of time and frequency. These mixed time-frequency mappings have been used to analyze the local frequency characteristics of a variety of signals and systems. Although much work has also been done to develop STFT and AF synthesis algorithms that can be used to implement a variety of time-varying signal processing operations, no such synthesis techniques have thus far been developed for the WD. In this paper, a signal synthesis algorithm that works directly with the real-valued high-resolution WD will be derived. Examples of how this WD synthesis procedure can be used to perform time-varying filtering operations or signal separation will be given.

Ultrasound therapy system

Abstract: An ultrasound therapy system comprises an annular array ultrasound transducer, a mechanical driver, a transmitter/receiver, and a controller. The controller includes an imaging controller, a heating controller, and a select controller. The mechanical driver mechanically drives the transducer to change at least one of the position and direction of ultrasound beams transmitted and received by the transducer. The transmitter/receiver may supply drive signals to the respective elements of the transducer, and receive the ultrasound echo signals from the elements. The imaging controller gives a first drive command to the transmitter/receiver, and at the same time drives the mechanical driver, radiates scanning ultrasound beams for tomographing through the transducer, and obtains a tomogram of a target portion in a patient from the echo signal derived from the transmitter/receiver. The heating controller drives the transmitter/receiver by a second drive signal to cause the transducer to radiate heating ultrasound beams. The heating ultrasound beams heat the target. These imaging and heating controllers are selectively activated by the select controller.

Polymer Modification of Fiber Optic Chemical Sensors as a Method of Enhancing Fluorescence Signal for pH Measurement

Abstract: The authors have prepared a pH fiber optic sensor based on fluorescence intensity. Fluoresceinamine is incorporated into an acrylamide-methylenebis(acrylamide) copolymer that is attached covalently to a surface-modified glass fiber via thermal or photopolymerization. The sensor gives instantaneous responses and reversible measurements over the pH range of 4.0-8.0 with signal-to-noise ratios of typically 275/1. The results indicate that specific fiber optic chemical sensors can be miniaturized and still retain sufficient signal intensity and stability.

Wireless telephone system

Abstract: A wireless telephone communication system for wireless, voice, data or voice and data terminals comprising apparatus at a central location for receiving one or a plurality of signals for communication with selected ones of wireless communication terminals, apparatus for converting the signals to spread spectrum radio frequency signals, a leaky transmission line located in a communication region, apparatus for applying the spread spectrum radio frequency signals to the transmission line for electromagnetic radiation within the region, at least one wireless communication terminal adapted to receive a predetermined one of the spread spectrum radio frequency signals and for demodulating it into an intelligible signal.

Survey of radio audience

Abstract: A technique for surveying an audience. A portable signal detector unit picks up audible sounds reproduced by a radio set from signals transmitted by a given radio station. Among the broadcast signals is one unique to that particular station. The unit includes means capable of identifying that signal to automatically electronically record the fact that the station is being listened to by the carrier of the unit.

Method and apparatus for in-situ measurement of head/recording medium clearance

Abstract: A method and apparatus for measuring the flying height of a slider supporting a magnetic transducer in-situ in a direct manner in an operational magnetic disk storage system. The method and apparatus produce relative motion between the magnetic transducer and a magnetic recording medium at a first velocity so that the resulting air bearing positions the magnetic transducer slider at a first flying height from the magnetic medium. A single signal of constant periodicity is written over a predetermined area of the recording medium by the magnetic transducer, and a readback signal is sensed from the predetermined area of the recording medium to produce a first signal. The flying height of the magnetic transducer slider is lowered to substantially zero, and a readback signal is sensed at the lowered flying height to produce a second signal. The first flying height is then calculated as the ratio, expressed in decibels, of the first and second signals times the wavelength divided by a constant. In an alternate embodiment a plurality of signals are recorded and readback signals are simultaneously sensed at two separate wavelengths. In a further embodiment, a signal is recorded which has a spectral content comprising a plurality of different frequencies, and readback signals are simultaneously sensed at two separate wavelengths.

Conformations of Signal Peptides Induced by Lipids Suggest Initial Steps in Protein Export

Abstract: Despite the requirement for a functional signal sequence in protein export, little is known of the conformational properties and membrane interactions of these highly hydrophobic amino terminal extensions on nearly all exported proteins. The Escherichia coli lambda phage receptor signal sequence was studied in phospholipid monolayers by circular dichroism and Fourier transform infrared spectroscopy; the signal peptide was shown to prefer an alpha-helical conformation when inserted into the lipid phase. However, interaction with the lipid surface without insertion induced the signal sequence, which is unstructured in bulk aqueous solution, to adopt a beta structure. These observations are combined in a model for the initial steps in signal sequence-membrane interaction in vivo.

Electric power steering system for vehicles

Abstract: An electric power steering system for vehicles including a driving control circuit (76, 100, 108) for feeding, in consideration of an output signal (S 1 , S 2 ) from a steering torque dectection mechanism (77) for detecting steering torque (Ts) acting on an input shaft (4), a drive signal (Va) to an electric motor (33) for producing auxiliary torque to be supplied to an output shaft (7). The steering system further comprises a detection mechanism (82) for detecting the steering speed (Ns) of the input shaft (4), and the driving control circuit (76, 100, 108) is adapted to feed the drive signal (Va) to the electric motor (33) in consideration of an output signal (S 4 , S 5 ) from the steering speed detection mechanism (82) as well as of the output signal (S 1 , S 2 ) from the steering torque detection mechanism (77). The driving control circuit (76, 100, 108) includes a micro-computer unit (76) for determining by address designation a control signal (T 3 , T 4 , T 5 ) as basis of the drive signal (Va) to the elecric motor (33), depending on the output signal (S 1 , S 2 ) from the steering torque detection mechanism (77) and the output signal (S 4 , S 5 ) from the steering speed detection mechanism (82).

Microphone actuation control system suitable for teleconference systems

Abstract: A microphone and loudspeaker arrangement for use in a teleconference system, wherein a plurality of microphones are held in a fixed relationship to a loudspeaker. The microphones are independently gated ON in response to (1) speech picked up by the microphone, (2) a loudspeaker signal driving the loudspeaker and (3) an electrical signal related to the microphone signals of the other associated microphones. A noise adapting threshold circuit generates a voltage level representative of background noise which is compared with the microphone signal of a respective microphone for determining whether the microphone is receiving speech. A decisional circuitry monitors the microphone signal of the associated microphone with respect to a MAX bus which carries microphone signals representative of the level of microphone signals at the other microphones. The decisional circuitry generates a signal indicating that the associated microphone is the first loudest microphone signal.

Direct broadcast satellite signal transmission system

Abstract: Audio and control signals are digitized and inserted in the horizontal intervals of the distributed composite television signal (Figure 3). The control signals are in the form of a data stream which includes a header (Figure 4) containing group address, sync, and program-related information applicable to all receiving units, and a plurality of portions (Figure 5) which are addressable to and contain information applicable to the control of particular individual receiving units in the addressed group. The information in the addressable portions (Figure 5) can be altered on a real time basis such that the system operator has direct control over certain functions of individual receiving units from the transmission end.

Video signal processing.

Abstract: In video processing, a motion compensated process and an equivalent linear process are performed on an input signal, the processing errors of which are computed and compared. The comparison is then used to control a mix between the outputs of the two processes to produce an output signal.

Encoding of transmitted program material

Abstract: An audio program is encoded with a subaudible binary code. A first value bit (mark) is a first frequency signal and a second value bit (space) is a second frequency signal. The coded message includes an initialization period constituted by a signal having the mark frequency. In decoding, the mark and space signals are detected through first and second band pass filters specific to the mark and space signal frequencies. The mark and space frequencies are sufficiently different to permit separate filtering. The time duration for each bit of the code is substantial. The decoder through a phase locked loop and integrator reads the bit on the basis of the average value of the bit over the duration of the bit. A synchronization signal provides for synchronous reading of the code. This signal that initiates the decoding operation is generated only in response to the coincident detection of the initialization signal, the notch and a mark response at the phase locked loop.

Data compression system

Abstract: A data compression system includes an input store (1) for receiving and storing a plurality of bytes of data from an outside source Data processing means for processing successive bytes of data from the input store includes circuit means (21-25) operable to check whether a sequence of bytes is identical with a sequence of bytes already processed, output means (27) operable to apply to a transfer medium (12) each byte of data not forming part of such an identical sequence, and an encoder (26) responsive to the identification of such a sequence to apply to the transfer means (12) an identification signal which identifies both the location in the input store of the previous occurrence of the sequence of bytes and the number of bytes in the sequence

Broadband microstrip antenna

Abstract: An antenna assembly which comprises a first laminar structure which includes a sheet of dielectric material having on one side a contiguous metal sheet and on the other side a strip transmission line adapted to be coupled with signal feeding means, and a second laminar structure, one side of which is in contact with the transmission line, and having on the other side, at least one region but preferable at least two concentrically arranged regions of a coated or cladded metal which serves as a radiator, characterized in that the transmission line is non-symetrically disposed with respect to the radiator.

Multipoint communication system having polling and reservation schemes

Abstract: In a multipoint communication system, first polling signals are sequentially and respectively transmitted to terminal stations on a broadcast channel from a central station, asking a request for reservation without waiting for a reply from the terminal stations. A reservation signal is transmitted on a multiple access channel from a terminal station requesting the reservation to the central station in response to the first polling signal addressed to it. A second polling signal is then transmitted on the broadcast channel in response to the reservation signal and the multiple access channel is reserved for a period of time variable in accordance with the reservation signal. A data signal is transmitted from the terminal station requesting the reservation on the reserved multiple access channel in response to the second polling signal.