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Showing papers on "Signal published in 1994"


Patent
06 Apr 1994
TL;DR: In this article, a load responsive output sensing circuit for monitoring and controlling parameters of an electrosurgical unit (ESU) relative to load and the RF energy, has been proposed.
Abstract: A circuit, for monitoring and controlling parameters of an electrosurgical unit (10), ESU, relative to load and the RF energy, has a load responsive output sensing circuit (11) that measures the ESU load. A signal modifier (12) attached to the sensing circuit (11) enhances the signals measured and transmits them to a buffer (13). An analog to digital converter (18), A/D, digitizes the signals and samples wave pulse train at about eight million samples per second. A data memory (21) stores the digitized signals. An RF drive clock (27) connects to the ESU output; a sample clock (19) uses phase shifting to interrogate the input signals to a processor (20), DSP, at a greater sampling rate of frequency than without. The DSP receives the stored signals from the data memory (21) and processes them while monitoring and calculating ESU parameters measured, i.e. voltage, current, power, load impedance, leakage current, peak to peak voltage, peak to peak current, spectral content and/or crest factor of the RF wave pulse train energy to use as controlling feedback to either a high voltage power supply in the ESU, regulating the RF drive pulses or both. A method monitors and controls the ESU relative to load and has the steps of collecting parameters with the ESU output sensing circuit (11) responsive to loads; enhancing signals with the signal modifier (12); transmitting signals to the buffer (13); converting signals with the A/D converter (18); storing signals in the data memory (21); receiving signals in the DSP, and processing, monitoring and controlling signals by repeatedly measuring ESU output parameters.

939 citations


Journal ArticleDOI
TL;DR: The secure communications systems based on chaotic carriers may be useful to increase privacy, but are not yet capable of providing a high level of security, according to this work.
Abstract: This work tests the level of security in secure communication systems based on nonlinear dynamics (NLD), or chaos In these systems, a chaotic carrier signal is used in a type of spread-spectrum signaling system, with the added benefit that the hidden information signal is buried at something of the order of −30 dB with respect to the chaotic carrier To investigate the level of security in such systems, an examination was conducted on a test set of chaotic carriers and hidden information signals prepared by the NLD research group at the Naval Research Lab The hidden signals included a triangle wave, a period doubled signal, and a chaotic signal that was different from the chaotic carrier The analysis process was to use NLD forecasting to predict the carrier dynamics, and then subtract away the predicted values to reveal the hidden signal or at least increase its signal-to-noise ratio with respect to the carrier In each case, it was a simple task to determine the power spectrum of the hidden signal once the prediction of the carrier was removed This was then used to create a “comb” filter to extract the correct frequencies from the FFT of the first two signals When this was done, the hidden signals were recreated with almost perfect accuracy In the third case, the hidden chaotic signal had a broadband component, so the spectrum was used to develop a Weiner filter which enabled the hidden signal to be reconstructed with only moderate accuracy, where the overall structure of the hidden chaotic signal was preserved, but the fine structure was lost As a further test, the processing approach was applied to a voice signal hidden in one-dimensional Lorenz data at −35 dB After subtracting away the carrier model, the voice signal was reconstructed with reasonable accuracy, and had the same characteristic structure In this case, no secondary filtering was applied The forecasting approach was then extended to allow for dynamic signal estimation using threshold detection, so that whenever a signal was detected, multiple predictions of the carrier behavior were made into the future This was tested on a square wave embedded at −42 dB in Lorenz data The extended approach was able to reveal the square wave with almost perfect precision, except in a few regions where it temporarily lost synchrony with the carrier This allowed for the elimination of the secondary filtering requirement entirely The final conclusion is that the secure communications systems based on chaotic carriers may be useful to increase privacy, but are not yet capable of providing a high level of security The paper concludes with a discussion of measures which may be taken to improve the security of such systems so that they may be applicable to areas where higher security is required

389 citations


Patent
02 Aug 1994
TL;DR: In this paper, a tracking system for tracking a portable or mobile phone unit utilizing an array of fixed wireless signal transceivers forming part of a wireless telephone system is presented. But the system is limited to the use of a single phone unit and does not include a processor for generating an emergency signal on detection of an emergency condition.
Abstract: A tracking system for tracking a portable or mobile phone unit utilizes an array of fixed wireless signal transceivers forming part of a wireless telephone system. The phone unit includes a processor for generating an emergency signal on detection of an emergency condition and transmitting the emergency signal to a remote monitoring station via the wireless telephone network. The emergency signal includes identifying information for identifying the phone unit, as well as identifying or control channel signals received by the phone unit from adjacent wireless signal transceivers which are retransmitted as part of the emergency signal to be used at the remote monitoring station to compute an approximate location of the phone unit.

379 citations


Book
01 Aug 1994
TL;DR: This volume provides an introduction to signal-detection theory, a subject fundamental to the design of detectors of weak signals in the presence of random noise, and to the designs of optimal and near-optimal receivers of communication, radar, sonar and optical signals.
Abstract: Written by a highly respected authority and researcher, this volume provides an introduction to signal-detection theory, a subject fundamental to the design of detectors of weak signals in the presence of random noise, and, in particular, to the design of optimal and near-optimal receivers of communication, radar, sonar and optical signals.

377 citations


PatentDOI
TL;DR: In this paper, a teleconferencing system with a video camera for generating a video signal representative of a video image of a first station B and a microphone array (150, 160) for receiving a sound from one or more fixed non-overlapping volume zones (151-159) into which the first station is divided.
Abstract: A teleconferencing system (100) is disclosed having a video camera for generating a video signal representative of a video image of a first station B. A microphone array (150, 160) is also provided in the first station for receiving a sound from one or more fixed non-overlapping volume zones (151-159) into which the first station is divided. The microphone array is also provided for generating a monochannel audio signal (170) representative of the received sound and a direction signal indicating, based on the sound received from each zone, from which of the volume zones the sound originated. The teleconferencing system also includes a display device (120A) at a second station A for displaying a video image of the first station. A loudspeaker control device (140) is also provided at the second station for selecting a virtual location (121) on the displayed video image depending on the direction signal, and for generating stereo sound from the monochannel audio signal which stereo sound emanates from the virtual location on the displayed video image.

351 citations


Patent
27 Jun 1994
TL;DR: In this paper, an apparatus is provided for manually entering information into a computer and a pressure sensor is attached proximate to the tip of at least one, but preferably all, of the fingers of a hand for generating a pressure signal that corresponds to the pressure of the finger tip against a surface, such as a desk top or table top.
Abstract: An apparatus is provided for manually entering information into a computer A pressure sensor is removably attached proximate to the tip of at least one, but preferably all, of the fingers of a hand for generating a pressure signal that corresponds to the pressure of the finger tip against a surface, such as a desk top or table top First and second acceleration sensors are also removably attached proximate to the finger tip for generating a first and second acceleration signal that is a function of the acceleration of the finger tip in first and second directions, respectively The first direction is different, and preferably orthogonal, to the second direction Preferably the sensors are mounted in a flexible, removable fabric glove, or the like A signal relay device, either wire-based or wireless, relays the signals of each sensor to the computer, which calculates from the signals the relative positions of each finger on the surface for generating keyboard, mouse, graphics tablet, or other forms of input data

345 citations


Book
01 Jan 1994
TL;DR: BiCMOS analogue building blocks sampled-data signal processing continuous-time signal processing current-mode signal processing analogue VLSI neural information processing data converters statistical modelling and simulation of analogue analogue CAD interconnects in analogue V LSI analogueVLSI design-for-test analogue integrated sensors.
Abstract: CMOS analogue building blocks BiCMOS analogue building blocks sampled-data signal processing continuous-time signal processing current-mode signal processing analogue VLSI neural information processing data converters statistical modelling and simulation of analogue analogue CAD interconnects in analogue VLSI analogue VLSI design-for-test analogue integrated sensors.

329 citations


Patent
30 Sep 1994
TL;DR: In this paper, a method and apparatus for driving an ultrasound transducer coupled to an ultrasound transmission disposed within an elongate catheter has been described, where the current of the modulated drive signal is monitored and the voltage thereof is varied in response to changes in the current in order to provide feedback control.
Abstract: A method and apparatus for driving an ultrasound transducer (14) coupled to an ultrasound transmission disposed within an elongate catheter (10) has a modulated output and utilizes feedback control. A modulating signal varying in amplitude and continuous in duration modulates an ultrasound transducer drive signal. The resulting modulated ultrasound transducer drive signal is likewise continuous in duration such that it lacks the abrupt accelerations which cause stress to be applied to the ultrasound transmission member in prior art devices. The current of the modulated drive signal is monitored and the voltage thereof is varied in response to changes in the current in order to provide feedback control. A transmission member breakage alarm provides an indication of transmission member breakage in the event that any comparison of the drive energy to the feedback control signal indicates that the desired ultrasonic vibration has been reached at a drive energy level less than the minimum drive energy level typically desired for such desired ultrasound vibration when the ultrasound transmission member is intact.

318 citations


Patent
13 Jan 1994
TL;DR: In this article, a cyclic redundancy check is performed on the digital data to determine the information contained in the video raster signal and to generate a compressed representation of that information, which can then easily and quickly be transmitted to a remote location for analysis and review.
Abstract: A system and method for accessing, controlling and monitoring a data processing device in which a video raster signal from the data processing device is analyzed to determine the information displayed on a video display monitor attached to the data processing device is used. The video raster signal is converted to a digital form and a cyclic redundancy check is performed on the digital data to determine the information contained in the video raster signal and to generate a compressed representation of that information. The information may then easily and quickly be transmitted to a remote location for analysis and review. Additionally, commands from the remote location can be transmitted to the system to control the data processing device.

316 citations


Patent
22 Jul 1994
TL;DR: In this paper, a multi-level encoded signal monitoring system and a universal broadcast code are provided, where a plurality of encoders are provided for encoding a predetermined program source signal.
Abstract: A multi-level encoded signal monitoring system and a universal broadcast code are provided. A plurality of encoders are provided for encoding a predetermined program source signal. The program source signal has a plurality of sequential segments. Each encoder is arranged for selectively encoding information on uniquely specified segments. A plurality of unique source information message data are selectively encoded on the uniquely specified segments to define the universal broadcast code with each unique encoded source information message data being representative of a level of distribution of the program signal. The predetermined program source signal is received and the encoded information on selected specified segments is decoded.

310 citations


Journal ArticleDOI
TL;DR: The linking-field neural network model was introduced to explain the experimentally observed synchronous activity among neural assemblies in the cat cortex induced by feature-dependent visual activity and gives a basic new function: grouping by similarity.
Abstract: The linking-field neural network model of Eckhorn et al. [Neural Comput. 2, 293-307 (1990)] was introduced to explain the experimentally observed synchronous activity among neural assemblies in the cat cortex induced by feature-dependent visual activity. The model produces synchronous bursts of pulses from neurons with similar activity, effectively grouping them by phase and pulse frequency. It gives a basic new function: grouping by similarity. The synchronous bursts are obtained in the limit of strong linking strengths. The linking-field model in the limit of moderate-to-weak linking characterized by few if any multiple bursts is investigated. In this limit dynamic, locally periodic traveling waves exist whose time signal encodes the geometrical structure of a two-dimensional input image. The signal can be made insensitive to translation, scale, rotation, distortion, and intensity. The waves transmit information beyond the physical interconnect distance. The model is implemented in an optical hybrid demonstration system. Results of the simulations and the optical system are presented.

Book ChapterDOI
01 Jan 1994
TL;DR: This work applies an algorithm to chose a best basis subset, tailored to fit a specific signal or class of signals, to two signal processing tasks: acoustic signal compression, and feature extraction in certain images.
Abstract: Wavelet packets are a versatile collection of functions generalizing the compactly supported wavelets of Daubechies. They are used to analyze and manipulate signals such as sound and images. We describe a library of such waveforms and demonstrate a few of their analytic properties. We also describe an algorithm to chose a best basis subset, tailored to fit a specific signal or class of signals. We apply this algorithm to two signal processing tasks: acoustic signal compression, and feature extraction in certain images.

Patent
30 Dec 1994
TL;DR: In this paper, a location system is used in a vehicle moving within an area at a selected speed and in a selected direction, where a heading sensor provides a heading signal representing the direction of movement of the vehicle.
Abstract: A location system is used in a vehicle moving within an area at a selected speed and in a selected direction. A heading sensor provides a heading signal representing the direction of movement of the vehicle. A speed sensor provides a speed signal based on available reference signals representing the speed of the vehicle. A storage device stores initial position data representing a selected initial position of the vehicle and checkpoint data representing a navigation checkpoint location. A database stores a plurality of records which each include geographic information data representing selective aspects of the area. A processor estimates a current position signal representing an estimated current position of the vehicle based on values of the heading signal, values of the speed signal, the initial position signal, and on previous values of the current position signal. Values of the current position signal correspond to records stored in the data base. A correction device selectively corrects the current position signal based on selected position inputs which indicate an approximate vehicle position relative to the navigation checkpoint location. An alerting device obtains an alerting signal indicating that the vehicle has reached a selected region within the area based on the current position signal and the geographic information data.

Patent
31 Aug 1994
TL;DR: In this paper, a medical communication system including a sensor worn on a living body to obtain physical information of the body, and generating a signal representing the physical information was presented, where the sensor was disposed on a side of the living body.
Abstract: A medical communication system including (A) a sensor worn on a living body to obtain physical information of the body, and generating a signal representing the physical information; (B) a first device disposed on a side of the living body, receiving the physical information signal from (A) the sensor, and including (b1) a first transmitter which transmits the physical information signal via a communication channel, (b2) a first receiver which receives, via the communication channel, an instruction signal representing an instruction of a medical worker directed to the living body and/or an attendant person, and (b3) an output device which outputs the instruction of the medical worker so that the living body and/or attendant person receives the instruction; and (C) a second device disposed on a side of the medical worker, and including (c1) a second receiver which receives, via the communication channel, the physical information signal from (b1) the first transmitter, (c2) an output device which outputs the physical information represented by the physical information signal so that the medical worker receives the physical information, (c3) an input device which is operable for inputting the instruction of the medical worker and generates the instruction signal representing the input instruction, and (c4) a second transmitter which transmits the instruction signal via the communication channel.

Patent
20 Apr 1994
TL;DR: In this paper, a system for delivering audio and/or video signals to users in connection with the provision of interactive television services is described, where various sources of such signals are connected to a digital network, such as a packet network.
Abstract: A system is disclosed for delivering audio and/or video signals to users in connection with the provision of interactive television services. Various sources of such signals are connected to a digital network, such as a packet network. Also connected to such network are control and application processors and interfaces to distribution arrangements such as cable television systems and telephone subscriber loops. Each user has a signal converter for receiving a digital signal from the distribution arrangement, converting such signal for viewing on a conventional television receiver and transmitting control packets to other elements of the system. The signal sources can include a data cache for storing recorded video and audio materials, a broadcast source for receiving broadcast signals, apparatus for composing multimedia signals from multiple sources and apparatus for running games. The various elements of the system can be situated at different geographical locations and operated by the control and/or application processors under software control to provide a variety of interactive television services.

Patent
22 Nov 1994
TL;DR: In this paper, an encoding mechanism for a medical sensor which uses a modulated signal to provide the coded data to a remote analyzer is presented. But, this signal is amplitude independent and thus provides a significant amount of noise immunity.
Abstract: The present invention provides an encoding mechanism for a medical sensor which uses a modulated signal to provide the coded data to a remote analyzer. The modulated signal could be, for instance, a pulse width modulated signal or a frequency modulated signal. This signal is amplitude independent and thus provides a significant amount of noise immunity.

Patent
27 Oct 1994
TL;DR: In this article, a line slicer divides each line of digital video signal into a plurality of channels such that each channel may be processed in parallel by channel signal processors (22a) through (22d).
Abstract: A digital television system (10) is provided. System (10) may receive a video signal at composite video interface and separation circuit (16). The video signal is separated into separate video signals by composite video interface and separation circuit (16). The separate video signals are converted to digital video signals in analog to digital converter circuit (18). Line slicer (14) divides each line of digital video signal into a plurality of channels such that each channel may be processed in parallel by channel signal processors (22a) through (22d). Each channel signal processor (22a) through (22d) may provide two lines of output for each line of video input. The processed digital video signals may be formatted for displays (26a) through (26c) in formatters (24a) through (24c).

Journal ArticleDOI
TL;DR: In this article, the effects of thermal and pileup noise in liquid ionization calorimeters operating in a high luminosity environment are studied. And the authors present the results of a study of the effect of thermal noise on the performance of pre-filter shaping.
Abstract: We present the results of a study of the effects of thermal and pileup noise in liquid ionization calorimeters operating in a high luminosity environment. The method of optimal filtering of multiply-sampled signals to obtain timing and amplitude from calorimeter signals is described. This method has some advantages over the traditional method of sampling the peak of a shaped signal, which include a reduced sensitivity to channel-to-channel variations in the pre-filter shaping parameters and good performance over a wide range of operating conditions. Analytic expressions for the variance of amplitude and timing measurements are found through a frequency domain approach. Implications for the choice of pre-filter shaping time, number and position of the samples, and digitization accuracy are discussed.

Book
01 Jan 1994
TL;DR: In this paper, Mehrdad Soumekh offers in-depth coverage of diverse issues such as physical and mathematical modeling of the problem, signal processing, reconstruction, analysis of resolution and system parameter constraints, hardware structure used for data acquisition, and the overall imaging system block diagram indicating how the acquired data are processed to yield the final reconstructed image.
Abstract: The past forty years have seen a number of imaging modalities developed for radar, sonar, diagnostic medicine, geophysical and celestial exploration, and non-destructive testing. Now, for those involved in designing and developing information processing tools for these imaging systems, author Mehrdad Soumekh offers in-depth coverage of diverse issues such as physical and mathematical modeling of the problem, signal processing, reconstruction, analysis of resolution and system parameter constraints, hardware structure used for data acquisition, and the overall imaging system block diagram (signal flow-chart) indicating how the acquired data are processed to yield the final reconstructed image. Fourier Array Imaging introduces the spatial Doppler phenomenon in conjunction with the most primitive signal processing tools and systems used in array imaging; presents terminologies and tools for two-dimensional signal processing; treats specific array imaging systems via the unifying framework of spatial Doppler processing, including phased-array imaging, synthetic aperture array (SAR and ISAR) imaging, passive array imaging, and bistatic array imaging with emphasis on transmission imaging problems of diagnostic medicine and geophysical exploration; devotes coverage to the analysis of resolution anticipated in an imaging system and to the constraints that are instrumental for selecting parameters of an imaging system; describes some of the classical methods used for image formation in array imaging systems and relates them to the spatial Doppler-based imaging via certain approximations.

Patent
29 Jul 1994
TL;DR: In this paper, a direct-view display consisting of an array of micro-mechanical modulators is described, and the modulator used to form the display comprises a suspended, vertically moving membrane and a substrate.
Abstract: A direct-view display comprising an array of micro-mechanical modulators is disclosed, he modulator used to form the display comprises a suspended, vertically moving membrane and a substrate. The device functions based on optical interference effects between the membrane and the substrate which cause the modulator to either substantially reflect or absorb an optical signal. The interference effects are a function of the size of the air gap between the membrane and substrate, which varies as the membrane moves. The membrane moves in response to a data signal, representative of an image, delivered to the modulator. The display generates an image based on the pattern of light and dark sections of the display corresponding to the reflectivity of each modulator at a given point in time.

Patent
07 Dec 1994
TL;DR: In this article, a pair of electrode arrays establish a capacitance on a touch detection pad, the capacitance varying with movement of a conductive object near the pad, measured synchronously with a reference frequency signal to thus provide a measure of the position of the object.
Abstract: Apparatus and method for a capacitance-based proximity sensor with interference rejection. A pair of electrode arrays establish a capacitance on a touch detection pad, the capacitance varying with movement of a conductive object near the pad. The capacitance variations are measured synchronously with a reference frequency signal to thus provide a measure of the position of the object. Electrical interference is rejected by producing a reference frequency signal which is not coherent with the interference.

Patent
30 Mar 1994
TL;DR: In this paper, a system for checking the initial calibration of a temperature measuring device that provides a temperature measurement signal in a catheter includes a comparison unit for comparing the magnitude of the temperature signal to a reference value indicating the normal body temperature of the patient.
Abstract: A system for checking the initial calibration of a temperature measuring device that provides a temperature measuring signal in a catheter includes a comparison unit for comparing the magnitude of the temperature signal to a reference value indicating the normal body temperature of the patient. The treatment procedure is disabled if the magnitude of the temperature signal is not within a predetermined range of the reference value.

Journal ArticleDOI
TL;DR: This paper gives results concerning the measurement of differential and integral nonlinearity of ADC's using the histogram method with a sine wave input signal and the effect on the results of harmonic distortion of the applied signal.
Abstract: This paper gives results concerning the measurement of differential and integral nonlinearity of ADC's using the histogram method with a sine wave input signal. We specify the amount of overdrive required as a function of the noise level and the desired accuracy and the number of samples required as a function of the desired accuracy, the desired confidence level, and the noise level. An analysis of the effect on the results of harmonic distortion of the applied signal is given. The error analysis assumes a mixture of coherent and random sampling rather than pure random sampling. >

Patent
19 Jan 1994
TL;DR: In this paper, a method and system for protecting a vehicle comprises detecting the actuation of the ignition and producing a first signal when actuated, sensing opening and closing of at least one door and for producing a second signal when the passenger door is open, energizing a camera and a recorder in the vehicle when the ignition is actuated and controlling the recorder in response to the first and second signals to record when any door is opened.
Abstract: A method and system for protecting a vehicle comprises detecting the actuation of the ignition and producing a first signal when actuated, sensing opening and closing of at least one door and for producing a second signal when the passenger door is open, energizing a camera and a recorder in the vehicle when the ignition is actuated and controlling the recorder in response to the first and second signals to record when any door is opened.

Journal ArticleDOI
TL;DR: A method that uses navigator echoes to monitor and compensate for signal fluctuations in a gradient‐echo sequence is described, and temporal fluctuations in image intensity were substantially reduced and improved functional activation maps were obtained.
Abstract: Functional magnetic resonance imaging is sensitive to signal fluctuations due to physiological motion and system instability. In this paper, motion-related signal fluctuations are studied, and a method that uses navigator echoes to monitor and compensate for signal fluctuations in a gradient-echo sequence is described. The technique acquires a "navigator" signal before the application of the phase-encoding and readout gradients and corrects the phase of the subsequently acquired imaging data. This technique was implemented on a 4 Tesla whole body system and validated on normal volunteers. With this technique, temporal fluctuations in image intensity were substantially reduced and improved functional activation maps were obtained.

Patent
16 Feb 1994
TL;DR: In this paper, the authors propose a method and modem for communicating serial input data over a transmission link, where the signal is demodulated and assembled into frames of parallel signal elements which are de-rotated by an inverse linear mapping.
Abstract: A method and modem for communicating serial input data over a transmission link. Serial input data is partitioned into parallel data elements prior to rotation by an invertible linear mapping. Resulting frames of parallel signal elements sequentially modulate a carrier, which is then transmitted over the link. After receipt of the modulated carrier from the link, the signal is demodulated and assembled into frames of parallel signal elements which are de-rotated by an inverse linear mapping. Thresholding the result of the inverse mapping recovers the parallel data elements, which are then re-assembled into serial output data. The linear mapping employs: 1) commuting rotation matrices for convolutionally rotating data vectors into signal vectors and vice-versa; 2) filter bank polyphase rotation matrices; or 3) computationally efficient multi-rate wavelet filter banks. Transmitter pre-emphasis places most of the information in lower baseband frequencies; complimentary de-emphasis occurs in the receiver. Logarithmic amplification of the baseband signal prior to carrier modulation improves modulation gain and transmit channel noise attenuation. Coefficients of the rotation matrix of the receiver are adaptively equalized to correct for transmission path distortion. FM double-side band is employed in systems requiring minimized cost and complexity. FM single-side band is employed in systems in which bandwidth reduction is desirable. AM is also employable.

Patent
12 Jul 1994
TL;DR: In this paper, a system and method for promoting use by an audience member of a portable broadcast exposure monitoring and/or recording device in accordance with a predetermined usage criterion is presented.
Abstract: A system and method are provided for promoting use by an audience member of a portable broadcast exposure monitoring and/or recording device (100) in accordance with a predetermined usage criterion. A sense signal (134, 136, 138) is provided indicating whether the device is being carried with the person of the audience member, and a time signal (118) corresponding with the sense signal is also provided. An indication (142, 144, 146, 148) to the audience member of whether the audience member's usage of the device has been in accordance with the predetermined usage criterion is provided based on the sense signal and the corresponding time signal.

Patent
22 Nov 1994
TL;DR: In this article, a receiver for pseudorandom noise (PRN) encoded signals consisting of a sampling circuit, multiple carrier and code synchronizing circuits, and multiple digital correlators is presented.
Abstract: A receiver for pseudorandom noise (PRN) encoded signals consisting of a sampling circuit, multiple carrier and code synchronizing circuits, and multiple digital correlators. The sampling circuit provides digital samples of a received composite signal to each of the several receiver channel circuits. The synchronizing circuits are preferably non-coherent, in the sense that they track any phase shifts in the received signal and adjust the frequency and phase of a locally generated carrier reference signal accordingly, even in the presence of Doppler or ionospheric distortion. The multiple correlators in each channel correlate the digital samples with locally generated PRN codes having multiple offsets, to produce a plurality of correlation signals. The plurality of correlation signals are fed to a parameter estimator, from which the delay and phase parameters of the direct path signal, as well as any multipath signals, may be estimated, and from which a range measurement may be corrected.

Journal ArticleDOI
TL;DR: In this article, a recursive algorithm for real-time digital pulse shaping in pulse height measurements has been developed, where the differentiated signal from the preamplifier (exponential pulse) is amplified and then digitized.
Abstract: Recursive algorithms for real-time digital pulse shaping in pulse height measurements have been developed. The differentiated signal from the preamplifier (exponential pulse) is amplified and then digitized. Digital data are deconvolved so that the response of the high-pass network is eliminated. The deconvolved pulse is processed by a time-invariant digital filter which allows trapezoidal/triangular or cusp-like shapes to be synthesized. A prototype of a digital trapezoidal processor was built which is capable of sampling and processing digital data in real time at clock rates up to 50 MHz.

Journal ArticleDOI
TL;DR: In this paper, the extinction ratio was measured for the converted signal compared to the input signal implying signal regeneration as well as wavelength conversion using SOA in a Mach-Zehnder configuration.
Abstract: Penalty free wavelength conversion is demonstrated at 2.5 Gbit/s over a wavelength span of 12 nm by the use of semiconductor optical amplifier (SOA)'s in a Mach-Zehnder configuration. An increase in the extinction ratio is measured for the converted signal compared to the input signal implying signal regeneration as well as wavelength conversion. >