Showing papers on "Data acquisition published in 1990"

Cardiac biopotential analysis system and method

Abstract: Patient leads (101) are connected to a patient (100) and ECG signals are picked up by the leads and transmitted over a patient cable (102) to a 16-channel ECG data acquisition system (104) with a serial interface. The data acquisition system (104) filters, amplifies and digitizes the ECG waveforms and sends the digitized data to a microcomputer (110) via a high speed synchronous serial line (106). The microcomputer (110) processes the serial data stream in order to generate computed data arrays. These arrays are then used in conjunction with predetermined reference arrays to produce diagnostic indices. These indices are displayed on the graphics display (108). Printed output is available on the hard copy output device (116) which is connected to the microcomputer (110). Interaction between the operator and the system is provided by means of a keyboard (112) and pointing device (114) with feedback on the graphics display (108).

The Meteorological Measurement System on the NASA ER-2 Aircraft

Abstract: A Meteorological Measurement System (MMS) was designed and installed on one of the NASA high-altitude ER-2 aircraft (NASA 706). The MMS provides in situ measurements of free-stream pressure (+ or - 0.3 mb), temperature (+ or - 0.3 C), and wind vector (+ or - 1 m/s). It incorporates a high-resolution inertial navigation system specially configured for scientific applications, a radome differential pressure system for measurements of the airflow angles, and a compact, computer-controlled data acquisition system to sample, process and store 45 variables on tape and on disk. The MMS hardware and software development is described, and resolution and accuracy of the instrumentation discussed. Custom software facilitates preflight system checkout, inflight data acquisition, and fast postflight data download. It accommodates various modes of MMS data: analog and digital, serial and parallel, and synchronous and asynchronous. Flight results are presented to demonstrate the capability of the system.

Assumptions implicit in remote sensing data acquisition and analysis

Abstract: The literature contains many examples of image acquisition and analysis which have been inappropriately applied and which have led to empirical results which may not be reproducible, or which are not conclusive. In this paper, we deal with eleven major assumptions which are implicit in the acquisition and in the analysis of passively sensed digital image data. It is hoped that an enumeration of such assumptions might lead to improved rules for image acquisition and analysis.

Rapid MR imaging of blood flow with a phase-sensitive, limited-flip-angle, gradient recalled pulse sequence: preliminary experience.

Abstract: To assess blood flow rapidly, a limited-flip-angle, gradient recalled pulse sequence was modified to acquire two views at the same phase-encoding step in successive repetitions. One view is obtained with first-moment flow compensation, while the second view is obtained with selectable flow encoding (non-zero first moment) along one direction. Blood flowing along the encoded direction acquires a phase difference between the two views, resulting in signal dependent on both direction and speed of flow. Stationary tissues undergo no phase change. Therefore, the phase shift between the two views produces an image that spatially renders flow direction and velocity. With a 24-msec repetition time, a 256 X 128 matrix, and two excitations, data acquisition is completed in 13 seconds per location (both a magnitude image and a flow image are produced at each location). Images generated with flow phantoms confirmed the accuracy of this method. Preliminary clinical evidence in 23 human subjects suggests that this method is useful in evaluating portal hypertension, distinguishing arterial from venous flow, distinguishing between slow flow and clot, and confirming the presence of clot. This method appears to be a fast, easy way to assess blood flow in large vessels.

Parallel pulse processing and data acquisition for high speed, low error flow cytometry

Abstract: A digitally synchronized parallel pulse processing and data acquisition system for a flow cytometer has multiple parallel input channels with independent pulse digitization and FIFO storage buffer. A trigger circuit controls the pulse digitization on all channels. After an event has been stored in each FIFO, a bus controller moves the oldest entry from each FIFO buffer onto a common data bus. The trigger circuit generates an ID number for each FIFO entry, which is checked by an error detection circuit. The system has high speed and low error rate.

System for managing a plurality of motor vehicles

Abstract: A system for managing a plurality of motor vehicles that are driven by different people is provided. A parking area having an entrance and an exit is provided with a data acquisition device for controlling user access, as well as a receiver that is disposed in the vicinity of a barrier and that receives vehicle operation data that is transmitted by a transmitter that is integral with the vehicle, with this data being transmitted to a central control unit that controls the barriers, the data acquisition device, and the receiver.

Description of a simultaneous emission-transmission CT system

Abstract: We are designing an instrument which will perform correlated emission-transmission image acquisition, but which departs from previous systems by incorporating a low-power x-ray tube and generator, rather than a radionuclide source, for the transmission image. The system uses an array of high-purity germanium (HPGe) detectors and detector electronics with energy discrimination circuitry to separate x-rays (at 100 or 120 kVp) from higher energy gamma rays from the 99mTc or 123j radiopharmaceutical injected into the patient. The data acquisition electronics have time constants matching the charge collection time (50 ns) of the HPGe detectors to maximize count-rate capabilities (up to 1 million cps per detector element), while maintaining adequate energy resolution (approximately 10% FWHM). Each detector channel has two energy windows for simultaneous transmission-emission imaging or for dual-energy x-ray studies. A host computer provides system control as well as data acquisition, data correction, tomographic image reconstruction, image display, and data analysis. As a radionuclide imaging system, this instrument will function as a single-slice SPECT scanner with high-count rate capabilities and excellent energy resolution for imaging short-lived radionuclides, improved photopeak discrimination and scatter rejection, and simultaneous imaging of multiple radionuclides. The system also will generate radiographic images in either a tomographic or projection scanning mode, while dual-energy x-ray CT will provide material specific imaging. However, the novel and potentially powerful capabilities of this instrument would derive from its inherent correlation of functional information from SPECT with precise anatomic information from CT or the material-specific morphologic information from dual-energy x-ray CT. The simultaneously acquired radiographic images should relieve the deficiencies of poor statistics and limited spatial resolution commonly associated with SPECT systems. Dual-energy xray CT also can provide an energy-corrected and anatomically-correlated map of attenuation coefficients for more accurate quantitation of emission radionuclide data.

Inertial-Dissipation Air-Sea Flux Measurements: A Prototype System Using Realtime Spectral Computations

Abstract: A prototype system for the measurement and computation of air–sea fluxes in realtime was tested in the Humidity Exchange Over the Sea (HEXOS) main experiment, HEXMAX. The system used a sonic anemometer/thermometer for wind speed, surface stress and sensible heat flux measurements and a Lyman-α fast hygrometer for latent beat flux. A small desktop computer combining both fast analog to digital (A/D) capabilities, external bus (IEEE-488) operation of a slow voltmeter/scanner unit, and a plug-in board for computation of turbulence spectra by Fast Fourier Transform was used for acquisition of 17 channels of data. At the end of a ten-minute averaging period, air–sea fluxes were computed from the velocity, temperature, and humidity variance spectra using the inertial-dissipation method. A second computer and data acquisition system was used for simultaneous computations of covariance fluxes for comparison. The sonic anemometer/thermometer proved to be well suited for this application: the velocity data...

Test system for acquiring, calculating and displaying representations of data sequences

Abstract: A system for testing electronic devices includes a waveform generator, a data acquisition system, and a computer. The waveform generator continuously generates a test signal having adjustable parameters set by the computer in response to user input. The data acquisition system acquires data representing the output of the device under test in response to the input signal and stores the last N acquired data values. The computer transfers a data sequence from the acquisition system to another memory and generates in a window on a terminal screen a wagveform display representing the stored data sequence. The computer also displays menu items referencing mathematical operations that may be performed on one or more data sequences. When a user selects one of the menu items, the computer prompts the user to select one or more windows containing waveform displays. Thereafter, the computer performs the selected operation on the data sequence controlling the waveform displays in the selected windows. When the result of the operation is a new data sequence, the computer stores the new data sequence in memory and then produces in a user-selected window a new waveform display based on the new data sequence.

Processing of SeaMARC swath sonar data

Abstract: A description is given of the acquisition and processing of data collected by a class of high-resolution sonar systems, the SeaMARC (seafloor mapping and remote characterization) swath mapping sonars. The SeaMARC system has two basic configurations: deep-towed, which acquires high-resolution backscatter imagery at slow survey speeds, and shallow-towed, which simultaneously acquires lower resolution backscatter and bathymetric information at higher speeds. Processing techniques applied to the data after acquisition are fairly independent of the initial towing configuration and include: compaction of the original data by decimation; radiometric corrections (noise removal, destriping, beam pattern correction, and contrast enhancement); derivation and merging of vehicle navigation with the sonar data; integration of backscatter and bathymetric information; and geometric corrections for plotting data in geographic coordinates. >

Underwater acoustic data acquisition system

Abstract: An acoustic data acquisition system for shipboard use is disclosed that allows for underwater acoustic data measurements at preselected submerged marine structural coordinates using a free swimming, quiet dynamically positionable remotely operated vehicle (ROV). Moreover, the disclosure provides a method of performing acoustic data acquisition with an ROV by first inputting the marine structural features by use of a computer aided design subsystem, determining the required trajectory path and hovering coordinates for data measurements, next, establishing the acoustic telemetry system for the remotely operated vehicle's control system to operate within and make an absolute positional fix to the marine structure's coordinates then, establish the ambient acoustic conditions of the worksite. The system is monitored and controlled from a computer based system. The system includes an ROV subsystem that operates in conjunction with a computer based long baseline underwater telemetry and positioning control subsystem, an acoustic transducer array attached to the ROV and a real time data-coordinate storage subsystem. A particular type of transducer suitable for use with this vehicle is a passive acoustic transducer array (hydrophones) that measures low level sound pressures and phase data that provides a detailed description of the sound power field emitted over the surface of the marine structure. Applications include oil/gas pipeline leak detection and location of malfunctioning underwater marine equipment.

Expert system for surveillance, diagnosis and prognosis of plant operation

Abstract: An expert system is used to perform surveil­lance, diagnosis and prognosis of a plant such as a nuclear reactor used in electrical power generation. The expert system uses one of real time actual plant data, previously stored actual plant data or simulated plant data as plant condition data to perform an evaluation of operating conditions in the plant. When real time actual plant data is used, a data acquisition system supplies the plant condition data. The expert system accesses the plant condition data, regardless of its source, periodi­cally as a surveillance frame is triggered by the rules in the root frame controlling the expert system. Other frames in the expert system perform diagnosis and prognosis of the plant condition.

An experimental study on reject ratio prediction for VLSI circuits: Kokomo revisited

Abstract: The authors report on an experiment to verify the accuracy of reject ratio predictions by the available approaches. The data collection effort includes instrumenting the wafer probe test to obtain chip failures as a function of applied vectors and running a fault simulator to obtain the cumulative fault coverage of these vectors. The accuracy of reject ratio predictions is judged by assuming earlier stopping points for the wafer probe, thereby gaining a measure of confidence in the final predicted value. The results of five different analyses are reported for over 70000 tested dies of a CMOS VLSI device. The five methods discussed predicted values for the reject ratio that vary by an order of magnitude at high values of fault coverage. It is shown that, with only an incremental effort during wafer probe, data collection that can be used to compare the relative accuracy of different models over a range of fault coverage is possible. >

Fast and robust range data acquisition in a low-cost environment

Abstract: It has been shown earlier that efficient active triangulation methods for range data acquisition can be devised by employing an appropriate time-space encoding. In this paper we show that the necessary computational burden to compute range values by means of these techniques can be reduced drastically by introducing weak geometrical constraints for the projector camera configurations. Furthermore, we suggest the concept of a virtual measurement coordinate system reducing the triangulation to simple one-dimensional LUT operations. Thus, the range acquisition technique can be implemented very fast in a low cost PC based image processing environment. We show how to calibrate the system and give some experimental results.

Seismic Wavefield Sampling: A Wave Number Approach to Acquisition Fundamentals

Abstract: The use of reflection seismic for the exploration of hydrocarbons entered a new epoch with the introduction of the horizontals tacking method in the early 1950s (Mayne, 1962, Sheriff and Geldart, 1982). In his pioneering article Mayne explained the benefit of using shorter receiver patterns for the preservation of reflected signals while delegating some of the groundroll suppression to the stacking process. For a long time the 6-fold stack was the ultimate of the seismic method, due to limitations in acquisition and processing hardware. Not until the late 1970s did reductions in station spacing, combined with a large increase in the number of recorded channels, allow higher stacking multiplicities leading to further drastic improvements in the quality of the final seismic reflection sections. The introduction of multiple-coverage recording called for the use of multichannel processing. Stacking, the multichannel process introduced first, was soon followed by post stack multichannel processes such as velocity filtering (Fail and Grau, 1963; Embree et al., 1963) and migration. Prestack multichannel processes became more feasible and even mandatory when the increase in number of recorded channels led to larger multiplicities and the reduced pattern lengths resulted in lower signal- to-noise (S/N) ratios. Some multichannel processes developed in the 1970s and 1980s are: multiple elimination, surface consistent statics correction, surface consistent deconvolution, slant stacking, dip move out (DMO) correction, and prestack migration. Most, if not all, of these techniques perform best for high multiplicities and regular spatial sampling. Though a variety of sophisticated multichannel processing techniques were developed by the best scientists in the industry, not much attention has been paid to the basic theories required for an optimal definition of acquisition parameters. Progress in the field of data acquisition has been driven by technology, experimentation and intuition, rather than by sound theories. A breakthrough in the formulation of seismic data acquisition techniques came with Nigel Anstey’s papers on the stack-array approach (1986a and b). Anstey’s recommendations, which were based on experience and intuition, need to be modified and extended on the basis of a more theoretical approach to the three-dimensional aspects of multiple coverage data. This theoretical background is provided here and the consequences for seismic data acquisition and seismic data processing are elaborated upon. The reader’s basic knowledge of the seismic method and of signal processing is assumed. Sheriff and Geldart (1982) is recommended as a more general introduction to seismic exploration Some aspects

Method and apparatus for verification of rail braking distances

Abstract: A braking distance verification system is disclosed which makes use of a specially designed pulse to voltage converter circuit and a portable computer-based data acquisition system to measure grade, speed, and distance information of any rail vehicle. The preferred embodiment of the device is particularly adapted for mass transit systems. It provides a method and apparatus for physical verification, under actual test conditions, that an adequate braking distance has been provided in each block of a signal block design system. The portable system may be used with any vehicle braking system which provides an electronic wheel tachometer or equivalent, or may utilize a portable doppler radar if tachometer information is not available.

Ground roll: Rejection using polarization filters

Abstract: Ground roll noise on land data sets overwhelms the desired reflection seismic signal unless special steps are taken in data acquisition and processing to control it. This is usually done in the field by the design of group arrays for data acquisition. On the other hand, if multicomponent data are acquired, it is possible to remove ground roll during processing using polarization analysis. Even though this processing is computation-intensive, the potential exists for obtaining results similar to conventional data acquisition, but with deployment of fewer sensors in the field with minimal group array effects. It also has potential for deriving new information.We describe a two-dimensional polarization-filter analysis for use with vertical and in-line sensors. A time-domain spectral matrix technique is developed since the recorded seismic signal is the superposition of multiple signals in the time domain, each with different frequency content and time-varying polarization. This technique is implemented by decomposing the signal into individual frequency components using narrow band-pass filters and defining the polarization characteristic using sliding time windows. We show that both incoherent noise and specific linearly polarized constituents can be successfully filtered.

Voltage and current harmonic content of a utility system-a summary of 1120 test measurements

Abstract: The results of a two-phase project regarding measurements of both voltage and current harmonics at numerous locations within a utility system are summarized. The voltage and current harmonics were measured, stored, and plotted at various substations during each phase of the project using a dynamic signal analyzer, a multipen plotter, and other data acquisition systems. This resulted in a total of 1120 measurements. Also, 24 h measurements were made at some locations to obtain time-of-day variations of the harmonic pattern. Various tables are presented to facilitate analysis of data and comparison of the voltage and current harmonics for multigrounded and unigrounded distribution systems and associated transmission lines. >

A new system for acquisition and processing of very high‐resolution seismic reflection data

Abstract: A new digital seismic data acquisition system and accompanying software have been developed by Ifremer to replace the analog equipment commonly used in very high‐resolution (less than 1 m) shallow marine seismic reflection surveys. The acquisition part, based on a Hewlett‐Packard 9000 microcomputer, is capable of sampling rates of up to 15 kHz for one channel. Signal processing and image processing can be performed either during the survey by the acquisition computer or after the survey with a software system that runs on a Sun workstation. The system has been developed for the specific requirements of coastal studies; understanding of the sediment layers in such studies requires a vertical resolution of around 1 m in the top 10 m of sediment. This system has been successfully used for the study of subtidal sand waves off the Cherbourg peninsula (France). The results, which revealed the internal structure of sand waves from about 3 m to 8 m high, correlated well with synthetic seismograms that were create...

System including inductive learning arrangement for adaptive management of behavior of complex entity

Abstract: A system and method for adaptively managing the behavior of, for example, a digital data processing system, using inductive learning techniques. The new system includes a data acquisition portion (10) that acquires event data in response to selected events. An inductive engine (11) generates profile knowledge in response to acquired event data during a learning phase, for storage in a profile knowledge store (15). A profile comparator (12), during an operational phase, subsequent to the learning phase, performs a verification operation in connection with comparing event data to said profile knowledge stored in said profile knowledge store (15). A control portion (14) enables event data acquired by said data acquisition portion to be directed to the inductive engine (11) during a learning phase and to the profile comparator (12) during an operational phase to thereby permit the comparator to perform a verification operation in connection with said event data acquired during the operational phase.

Apparatus for monitoring and controlling electrostatic discharge

Abstract: The apparatus for monitoring and controlling electrostatic discharge control systems provides an automated sequence of electrostatic discharge control and soldering iron performance measurements that can be used to verify the continued integrity of the electrostatic discharge control systems. This is accomplished by a microprocessor controlled central data acquisition and control unit that controls a plurality of test units. Each work station in the manufacturing environment is equipped with a test unit that performs a number of measurements and tests of various electrostatic discharge control systems and soldering iron performance. The central data acquisition and control unit sequentially and automatically polls each individual test unit to perform or prompt the operator to participate in the designated measurements. The data obtained by each test unit is transferred to the central data acquisition and control unit where the data is analyzed and recorded. This data can be used to generate an alarm when one of the test units indicates a failure of the associated electrostatic discharge control systems or the soldering iron operation. In addition, the collected data provides an on-going record of long-term performance of the electrostatic discharge control systems and the individual soldering irons at each test unit.

Mathematical morphology: a tool for automated GIS data acquisition from scanned thematic maps.

Abstract: Over several years, the demand for digital data has grown as geographical information systems were im- plemented. Because of the cost of database creation, data acquisition should unquestionably be automated as much as possible. Today, scanning devices produce a huge amount of data that still needs complex processing. This paper proposes an original approach using image processing tools coming from Mathematical Morphology theory to acquire GIs data from scanned thematic maps. These tools are used in order to obtain a segmentation prior to radiometric analysis. To illustrate the methodology, a subset of the Belgian soil map is treated. URING THE LAST FIFTEEN YEARS, dramatic growth in the use of geographical information systems (GIs) occurred in many disciplines. This technology provides multipurpose land infor- mation systems as a means of dealing with the land records modernization problem. Natural resources modeling and man- agement also benefit greatly from this technology by integrating a tremendous amount of data. By far, data capture is the most expensive task in a GIs ap- plication. To make full use of GIs capabilities, accurate and up- to-date information must be provided. The usual method of acquiring data from existing maps is by manually following lines on a digitizing table. Though advertising brochures usually show an operator happily at work, this method is actually a very tedious and boring operation with a high probability of errors due to either duplicating or omitting information (Doyle, 1978). To overcome this predicament, techniques for automated and semi-automated data capture have been developed during the past several years. Two major "automated processes being used today for data acquisition are line following and map scanning. Line following techniques are used for digitizing lines such as stream networks or contour lines while map scanning allows the extraction of point, line, and surface information. A recent opinion of map scanning (Faust, 1987) stated that "the existing multistep-inter- active procedure for creating point, line, and polygon structures with the appropriate attributes must be automated to a Kreater extent." 1i ibis paper, we present a method to automaLe data acquisition with the Belgian soil map which is of interest for natural resources oriented GIS as an example. The major feature of the method is its ability to segment the map into its different areas prior to radiometric analysis. This process makes use of Mathematical Morphology, a new image processing technique. The results indicate that the method is consistent with human interpretation of the map. However, it is not the claim of the authors to suggest that a methodology 'could be applied without distinction to any kind of thematic maps, because each has its own peculiarity. Nonetheless, our opinion is that some tools used here could be widely employed for processing other scanned maps.

Control system for remote controlled aircraft

Abstract: The invention relates to a control system for a remote controlled aircraft. This system comprises on one hand, an substructure on the ground provided with computing means, data acquisition means and radio transmission means, and on the other hand, an on-board apparatus provided with analogous means and sensors for the parameters of the behavior of the aircraft. The substructure on the ground and the on-board apparatus are adapted to exchange data in order to assure the stabilization and the piloting of the aircraft, and the provide specific orders as a function of the application.

Real-time digital control, data acquisition, and analysis system for the DIII-D multipulse Thomson scattering diagnostic

Abstract: A VME‐based real‐time computer system for laser control, data acquisition, and analysis for the DIII‐D multipulse Thomson scattering diagnostic is described. The laser control task requires precise timing of up to eight Nd:YAG lasers, each with an average firing rate of 20 Hz. A cpu module in a real‐time multiprocessing computer system will operate the lasers with evenly staggered laser pulses or in a ‘‘burst mode,’’ where all available (fully charged) lasers can be fired at 50–100 μs intervals upon receipt of an external event trigger signal. One or more cpu modules, along with a LeCroy FERA (fast encoding and readout ADC) system, will perform real‐time data acquisition and analysis. Partial electron temperature and density profiles will be available for plasma feedback control within 1 ms following each laser pulse. The VME‐based computer system consists of two or more target processor modules (25 MHz Motorola 68030) running the VMEexec real‐time operating system connected to a Unix‐based host system (also a 68030). All real‐time software is fully interrupt driven to maximize system efficiency. Operator interaction and (non‐real‐time) data analysis takes place on a MicroVAX 3400 connected via DECnet.

Multifunctional identification and information card

Abstract: An identification and information card comprising an integrated electronic circuit including a processor. The electronic circuit is capable of contactlessly transmitting data to, and receiving data from, a data acquisition system in response to an electromagnetic interrogation field. The card is provided with a magneto/optical memory which contains data encoded according to a secret key. The coded data can be read by the data acquisition system and converted into electrical signals which are contactlessly transmitted to the card and are decoded by the processor. The card contains security data for protection against unauthorized use.

Measurement method and apparatus for monitoring the kinetics of polymerization and crosslinking reactions by microwave dielectrometry

Abstract: The experimental apparatus employed for monitoring fast polymerizing and crosslinking processes is described in detail. The measurement method for the particular application is widely discussed and the resulting performances of the measurement technique are reported. As an example, the experimental results for polymerization and crosslinking reactions of n-butyl acrylate and 1,6-hexandiol-diacrylate are shown and the accuracy of the data acquisition is demonstrated.

Microcomputer-controlled freezing, data acquisition and analysis system for cold hardiness evaluation.

Abstract: A computerized system capable of controlling the freezing rate and collect- ing, storing, and analyzing data from multiple samples to determine their freezing point using low-temperature exotherm analysis is described. Details include electrical diagrams of modifications to the multiplexer/amplifier interface to provide additional signal amplification and permit control of the freezer's compressor. Computer software is described that permits variable temperature decline rates. Data analysis consists of a program in "C" that sequentially compares each data point in a low-temperature exotherm profile. Low-temperature exotherms are identified by a user-specified min- imum differential between sequential data points. Examples of exotherm output and data analysis are given.

Encoding techniques for multiple source point seismic data acquisition

Abstract: Recent advances in vibrator electronics have made the use of encoded sweeps for multiple source point data acquisition possible in an operational setting. Alternatives to existing operational multiple source point data acquisition techniques, using complementary series and E‐codes, are developed in this paper. Most existing techniques are, at each source point, a series of linear sweeps of predetermined polarity that enables the cancellation of the contributions from the other source points in processing. The complementary series techniques developed here also choose polarities such that the contributions from other source points can be cancelled. Pairs of E‐codes have been found that produce no crosscorrelation, which makes it possible to use E‐codes to produce a dual source point technique that is fundamentally different from the more conventional techniques. Field tests are carried out using E‐codes in dual source point schemes. Records from the respective source points are readily separated from the c...

Measurement of the torque-speed characteristics of induction motors using an improved new digital approach

Abstract: A measurement technique for determining the torque-speed characteristics of induction motors is presented. This technique is in compliance with the IEEE standard test procedure for polyphase induction motors and generators. It is based on the acceleration method which is performed under no-load conditions. A fast data-acquisition system is used to record the speed and other signals of interest. The data is processed digitally with the objective of removing undesired extraneous signals while preserving the accuracy of the machine characteristics over the complete range of speed. To achieve this objective, algorithms for performing adaptive window-size average filtering and numerical differentiation are developed. Experimental tests performed on 1 HP and 600 HP induction motors confirm that this approach has several advantages over other methods. It produces very accurate results over the full dynamic speed range of the machine and permits precise correlation between the switching transients on the line with the variation of the speed signal. >