Abstract: The method serves to determine the vibrational state of turbine blades, arranged on a rotor shaft, mounted such as to rotate in a housing and/or of guide vanes. At least one electromagnetic wave is transmitted into a flow channel in the vicinity of the blades, using means for the generation of at least one electromagnetic wave. The electromagnetic waves are at least partly reflected from at least one blade. The reflected part of the at least one electromagnetic wave is received by means for receiving and the vibrational state of the corresponding blade is determined from a signal corresponding to the at least one received electromagnetic wave.

Abstract: A power generator unit condition monitoring system can receive a frequency profile generated by a frequency generating component and can transmit the received frequency to a frequency profile analyzer. The frequency profile analyzer analyzes the transmitted frequency profile and compares the profile against a database. The database can stores normal and abnormal frequency profiles.

Abstract: A precision sensor assembly for rotating members in a machine tool comprises a rotor unit (16) rigidly fixed to a rotor portion (2a) of the machine tool and including a sensor (5) for detecting vibrations produced by the operation of the machine tool, the sensor (5) comprising a piezoelectric sensitive element (6) and members (7, 8) for mechanical amplification of the vibrations. The members (7, 8) comprise at least one resonant system composed of an elastic element (8) and a counter-mass (7) acting on the piezoelectric sensitive element (6). The rotor and stator units (16, 17) comprise inductively coupled transmitting and receiving elements (10, 11) for transferring the signals from the piezoelectric element (6) contactless to the stator unit (17). The stator unit (17) may include an electric amplifier (13) for further amplifying the transmitted signals.

Abstract: A device for indicating a beat level L, the device including an analyzer which responds to a reference frequency ? and a harmonic coefficient B to extract from an evaluation signal E a first acceleration signal ?B at a frequency equal to the product of reference frequency ? multiplied by harmonic coefficient B; and a second acceleration signal ?B-1 at a frequency equal to the product of reference frequency ? multiplied by the harmonic coefficient minus one; and it further includes a control circuit CC which receives acceleration signal ?B, ?B-1 to produce beat level L.

Abstract: A method of processing oscillatory response data from a resonant system includes: obtaining data measuring an oscillatory response of the system at a plurality of evenly spaced time intervals; obtaining a plurality of reference frequencies from the data at a plurality of times in the data, each reference frequency preferably being the natural frequency of a mode of the response at the respective time or an estimate of the natural frequency; and transforming the data to an uneven data set having unevenly spaced time intervals by adjusting the evenly spaced time intervals according to the values of the measured reference frequencies. The method can transform non-stationary response data to make it effectively stationary, and thus in a more useful form for further analysis. A method of analysing a resonant system and an apparatus for processing oscillatory response data are also provided.

Abstract: A method for analyzing vibration including: acquiring a vibration signal; isolating a vibration signal event in the acquired signal; determining a frequency of a damped sinusoid of the vibration signal event, wherein the damped sinusoid characterizes the vibration signal event, and using the characteristic damped sinusoid to identify an occurrence of the vibration signal event in another vibration signal.

Abstract: A cyclic time averaging method is directed at processing time-domain vibration data of the machine to produce an averaged time waveform over a selected cyclic time period. It is not necessary to employ a triggering signal to obtain the averaged time waveform.

Abstract: A method of determining speed of rotation of a motor is provided. The method involves collecting samples with a measuring sensor at a sampling frequency, set on the basis of mechanical vibration of the motor, for the duration of a measurement period and storing the samples in the memory of a data carrier as measurement data of a fixed format. The speed of rotation of the motor is determined from the measurement data by determining the cycle length of a periodic vibration signal in the time domain by a maximum likelihood estimate calculated by maximizing a maximum likelihood function adjusted to the measurement data, the speed of rotation being obtained from the frequency point where the maximum likelihood function obtains its maximum value.

Abstract: This invention is a method to determine the condition of rotating equipment, namely drive spindles, to enable the timely maintenance or replacement of same. The method uses an electrical signal from a vibration sensor mounted on part of the drive train to measure the level of vibration energy when the equipment is rotating under loaded and unloaded conditions. The relative vibration under the loaded and unloaded conditions is used as an indicator of equipment condition. Typically there is more vibration under load when the equipment is in good condition. When the level of vibration under the no-load condition matches or exceeds that seen under load, the equipment needs to be serviced or replaced.

Abstract: A method and apparatus for wireless transmission of data through a communications channel between at least two local data sensors (for example automotive diagnostic data sensors or NVH sensors), which may include a primary data-processing function, and data-processing function (for example a PC) to receive data therefrom. The system provides for asymmetrical division of the communications channel on a frequency or time-division or packet-switching basis so that the corresponding asymmetrical data transmission requirement of the local data sensors are matched to the capacity of their respective sub-channels whereby a single channel is capable of transmitting all the required data. A particularly practical application is to noise vibration harshness analysis of wireless-transmitted data from three-dimensionally spaced NVH sensors enabling spacial pinpointing of vibration sources in automotive warranty analysis studies.

Abstract: A process is performed for testing the quality of a unit such as an electromotor, which has at least one mobile part, which is mobile within a given frequency range with varying frequencies and is capable of exciting the unit to oscillate. In the method, a frequency of the mobile part at least within a first interval of the frequency range is varied with a first rate of change. The frequency of the mobile part within at least a second interval of the frequency range is varied with a second rate of change. The second rate of change is lower than the first rate of change. The oscillation amplitude of the unit is recorded and the unit is assessed as useful or unusable by evaluation of the recorded oscillation amplitude.

Abstract: A vibration information transmission apparatus for improving efficiency of field wiring of a vibration monitoring/analyzing system includes transmitters (11-1 to n) for converting vibration information from vibration sensors (2-1 to n) for detecting vibration of an object to be measured, into an electric signal and outputting the electric signal to a digital network (DN). The transmitters (11-1 to n) includes in the same casing, a transducer circuit (18) for converting the vibration information from the vibration sensors (2-1 to n) into an analog electric signal, an A/D conversion circuit (19) for converting the analog electric signal from the transducer circuit (18) into a digital signal, and a network interface (20) for outputting the digital signal from the A/D conversion circuit (19) to the digital network (DN).

Abstract: A measuring method to determine the noise emission of an electric motor is proposed in which the vibrational excitation of the running electric motor is measured by a laser vibrometer device and this measured vibrational excitation is correlated with a noise level.

Abstract: An apparatus for analyzing the condition of a machine, comprising: at least one input for receiving measurement data from a sensor for surveying a measuring point of the machine; data processing means for processing condition data dependent on said measurement data; said data processing means comprising means for performing a plurality of condition monitoring functions (F1, F2, Fn); and a logger for registering use of at least two of said condition monitoring functions (F1, F2, Fn); wherein said logger is adapted to register use of a first condition monitoring function a first rate; and said logger is adapted to register use a second condition monitoring function at a second rate.

Abstract: An apparatus having a non-vibrating contact potential probe. The non-vibrating contact potential probe is capable of measuring the chemical and geometrical irregularities on a rotating shaft. The chemical and geometrical information can be used to determine various properties of the rotating shaft.

Abstract: A measuring system for structure-born noise measurement of machine elements in machine housings. The measuring system is fixed to the machine housing via a lubrication hold opening. A mounting pin with a continuous bore hole. A housing receives a printed circuit board provided with electronic components for signal evaluation. A vibration snesor and vibration sensor housing rotationally mounted in relation to the mounting pin when the mounting pin is screwed into the lubrication hold opening. The vibration sensor housing is rotationally fixed to the machine housing in a non-positive fit via a metal bushing when the mounting pin is screwed in an end position. The vibration sensor is located adjacent to the metal bushing whereby structure-born noise is directly transferred from the machine housing to the vibration sensor via the metal bushing.

Abstract: A method for detecting vibrations of a shaft of an electrical machine includes measuring at least one of a shaft voltage and a shaft current and analyzing the measured at least one of the shaft voltage and the shaft current so as to determine the vibrations. In addition, an apparatus for detecting vibrations of a shaft of an electrical machine includes a first grounding device disposed at a first point on the shaft on a first side of the electrical machine and a second grounding device disposed at a second point of the shaft on a second side of the electrical machine. The second grounding device is configured to measure at least one of a shaft voltage and a shaft current.

Abstract: A sensor unit is supported on a stationary ring which does not rotate even when it is in use, and the rotation of the rotary ring can be detected by a rotation detecting sensor held within the sensor unit. Within the sensor unit, besides the rotation detecting sensor, there are disposed other sensors such as a temperature sensor and a vibration sensor, thereby being able to detect the rotation speed and the rotation number of the wheel supported on the rotary ring, and the other car driving conditions.

Abstract: A bearing vibration measuring apparatus is an apparatus of measuring vibration of a bearing. The bearing vibration measuring apparatus detects a vibration component generated from the bearing in a state of pressing one of an inner ring and an outer ring of the bearing in an axial direction while relatively rotating other of the inner ring and the outer ring to detect a defect of the bearing based on the vibration component. The bearing vibration measuring apparatus includes a driving mechanism elongated and contracted for inclining the inner ring or the outer ring.

Abstract: A configurable vibration sensor having a sensor circuit, an analog-to-digital converter and a processor is provided. The sensor circuit employs a vibration sensing element and a variable bandwidth filter controllable by the processor. In addition to the variable bandwidth filter, other configurable elements may also be employed in the sensor circuit, including a variable gain amplifier. These configurable elements allow the configurable vibration sensor to be configured for different vibration measurement applications when measuring vibrations from vibrating structures such as machinery and the like.

Abstract: An inspection carriage provides for remote inspection of the Z-shroud and snubber regions of the blades of a steam turbine, while the blades remain in the turbine. The carriage includes a non-destructive inspection probe such as a meandering wave magnetometer probe or eddy current probe mounted on a slider, so that the probe may be moved along a radial axis, skew axis, axial axis, and rotation axis. Cameras are provided on the carriage so that the probe may be remotely guided into the region to be inspected.

Abstract: An acoustic sensor for monitoring machining processes in machining tools, e.g. grinding machines, includes a stationary unit, or stator (21) and a rotating unit, or rotor (23), the latter being coupled, for instance, to the grinding wheel and rotating with it. The rotor includes a support (45;45?) and a piezoelectric transducer (33). The position of the transducer is defined and locked without using glues by means of mechanical elements (48, 53, 54; 63, 64; 74, 78) that may include elastic elements such as springs. The rotor also includes a printed circuit board (55), connected to the piezoelectric transducer, with a charge amplifier (37) for amplifying the output signal of the piezoelectric transducer. The rotor is electrically coupled to the stator by means of transformer type couplings (30, 31).

Abstract: A manufacturing apparatus which includes a rotary machine, includes: a plurality of accelerometers configured to measure diagnosis time series data attached to the rotary machine at locations where variations of the rotary machine are different; a frequency analysis device configured to perform a frequency analysis on the diagnosis time series data measured by the plurality of accelerometers; a time series data recording module configured to generate diagnosis data based on variations in characteristics of vibration corresponding to an analysis target frequency and to record the diagnosis data; and a life prediction unit configured to analyze the diagnosis data to determine a life span of the rotary machine.

Abstract: A processing machine, in particular a processing center, with a spindle, a tool clamping device, a converter unit with a spindle motor, at least one oscillation sensor and a balancing apparatus is disclosed. The oscillation sensor(s) and the balancing device are connected for signal transmission with a control device of a converter unit. The control device includes a balancing program. The processing machine with this type of automatic balancing system requires less wiring and less space than conventional systems.

Abstract: A method of monitoring the condition of a thermal barrier coating on a turbine blade or vane during operation of the turbine is provided. The method includes providing a means for receiving acoustic output of the blade or vane during operation of the turbine and monitoring the acoustic output over time, to determine the condition of the thermal barrier coating on the blade or vane. The acoustic output arises from a force on the blade or vane, such as that due to impact of particles, a pulse of gas pressure or constant gas flow. An apparatus employing the above method for monitoring the condition of the thermal barrier coating during operation of the turbine, is also provided.

Abstract: A method and system for detecting precursors to compressor stall and surge in which at least one compressor parameter is monitored to obtain raw data representative of said at least one compressor parameter. The raw data is pre-processed using a frequency demodulator to produce pre-processed data, and the pre-processed raw data is post-processed using a Kalman filter to obtain stall precursors.

Abstract: Novel tracked orders (i.e., tracked orders that are not present in “healthy” machinery) are useful for locating bearing anomalies. Accordingly, a method for locating bearing anomalies in machinery is provided that includes receiving vibration measurements acquired from the machinery, analyzing the vibration measurements to identify novel tracked orders indicative of bearing anomalies, and ascertaining the location of a bearing anomaly by relating a novel tracked order thus-identified to one or more further tracked orders. Thus, the novel tracked order does not merely indicate the occurrence of a bearing anomaly, but, in combination with the one or more further tracked orders, allows the bearing anomaly to be traced to a particular position.

Abstract: The present invention provides a device for determining the dynamics of a tool sited in a CNC machine, as encapsulated by the Frequency Response Function. The device uses an actively controlled electromagnet to excite forces on the tool. The force is excited in a non-contact manner, allowing the force to be applied to both a stationary and a rotating tool. The displacement is measured by standard means, such as accelerometers, optical displacement or capacitance sensors. The ratio of the force and the displacement in the frequency domain is the Frequency Response Function. The force may be applied as a pure sine wave, providing the Frequency Response Function at the frequency of the sine wave. Varying the frequency of the sine wave provides the Frequency Response Function over the range of frequencies of interest. The control of the force profile is handled entirely by the automated controls and requires no special skills, training or manual interaction by the user.

Abstract: A method and apparatus for detecting problems in a rotating machine is disclosed. The method and apparatus include creating a definition of the rotating machine using a plurality of templates that specify components and functional characteristics of the components. In addition, the method and apparatus include identifying a plurality of sensors configured to provide operational data related to the rotating machine and defining a plurality of problem rules including logical expressions by which machine faults are deduced from specified portions of the operational data. Further, the method and apparatus include performing an analysis of operation of the rotating machine, the analysis including acquiring actual operational data from the plurality of sensors and applying the problem rules and templates to the operational data to detect faults in the rotating machine and in response thereto generating an indication when a fault is detected.

Abstract: A wafer for placement in a pipe. The wafer includes a housing having an outer surface and an orifice adapted to allow fluid flowing in the pipe to pass through the housing. The housing has at least a first port extending into the housing from the outer surface for holding a first acoustic transducer. The wafer includes means for attaching the housing to the pipe. A method for obtaining information about fluid in a pipe.

Abstract: A computer implemented process is provided for assessing and characterizing the degree of success or failure of an operational event of a machine system such as a fluid compressor machine or turbine machine or the like on a continuous numerical scale. The computer implemented process develops and tracks machine unit signatures, machine site signatures and machine fleet signatures to evaluate various operational events and provide fault detection. At least some sensor data acquired from the machine system during an operational event is transformed to correct or at least reduce variabilities in the data caused by ambient conditions and fuel quality. The transformed data is then analyzed using statistical methods to determine how closely the operational event conforms to an expected normal behavior and the information is used to develop a single comprehensive quality assessment of the event.

Abstract: In a method for determining the state of a road during driving of a motor vehicle, the sound which is generated when a vehicle tire rolls on an underlying surface is sensed. A frequency signal is determined by means of a sound level signal which describes the sound, and is divided into at least two sub-zones by means of at least one limiting frequency. The sub-zones are each assigned to an associated frequency band, and an intensity value is determined for each of at least two frequency bands from the assigned sub-zone of the frequency signal. The intensity value is characteristic of the sound intensity which is present in a frequency band. An intensity ratio is formed from two intensity values by dividing the first intensity value of the first frequency band by the second intensity value of the second frequency band, and is used to determine the state of a road.

Abstract: The present invention provides a multi-level model-based intelligent agent diagnosis system and method for computer-controlled machinery operative to reduce the complexity typically associated with conventional model based diagnostic systems. The system utilizes a plurality of intelligent agents arranged in a plurality of physically hierarchical layers such that the tasks associated with accomplishing model based diagnosis are distributed amongst the intelligent agents if each layer wherein information gathered from a first lower level intelligent agents is processed by at least one other higher level to realize system fault diagnosis. The system provides increased processing speed of modeling and/or model identification such that faster and more accurate failure isolation and identification is accomplished.

Abstract: A system for determining impulse events of an asset by sampling and digitizing a complex signal sensed by a transducer monitoring the asset into a digitized signal with a sampling device operatively coupled to the transducer, transforming the digitized signal into a plurality of maximum and minimum value pairs each pair having an associated location correlated to a relative movement of a moving member of the asset with a processor operatively coupled to the sampling device, and a monitor and/or a computerized condition monitor having the processor integrally formed therewith or operatively coupled thereto for comparing at least one of the plurality of maximum and minimum value pairs and its respective location to at least one known value for determining impulse events based on the comparison step for providing asset protection.

Abstract: A tool and method to identify a defect in a vehicle through a vibration frequency is provided. To identify the defect in a vehicle, a sensor senses a vibration frequency and generates a signal in response to the vibration frequency. In addition, a signal spectrum analyzer communicates with the sensor and identifies the defect in response to the signal.

Abstract: To eliminate unwanted vibrations caused by synchronous disturbances, such as synchronous disturbances caused by an imbalance, for example, the invention proposes a compensation device for closed loop compensation of a synchronous disturbance in a rotating machine comprising a rotor (64) magnetically suspended by at least one radial magnetic bearing (63) comprising electromagnets (631, 632) driven by amplifiers (61, 62), a radial detector device (633, 634) for sensing the axial position of the rotor, and a closed loop servocontrol circuit connected to said detector device and to said electromagnets and comprising a control circuit (5) for controlling the energization of the electromagnets that supplies a control signal (u) to said amplifiers in response to signals supplied by the detector device to maintain the rotor in a predetermined axial position. The compensation device comprises means (100; 200; 300) for generating a signal for compensating the synchronous disturbance.

Abstract: A device and system are provided for monitoring acoustic emissions from machinery to indicate levels of detected sound waves. Each incorporates an acoustic sensing device which incorporates a housing assembly constructed for removable attachment between a surface mounting region of the machinery and a measuring instrument to define a coupled state. An acoustic emissions sensor is disposed in the housing assembly's interior to detect sound waves propagating through the surface mounting region and to produce detection signals for processing by the measuring instrument. A methodology for monitoring acoustic emissions is also provided.

Abstract: A vibration control system for a rotary machine having a rotor, includes a sensor disposed within the rotary machine for sensing vibration of the rotor, a vibration damping device disposed within the rotary machine for imparting a reaction force to the rotor, and a controller arranged in operable communication with the sensor and the vibration damping device. The controller is adapted to receive a sensor signal from the sensor and to send a control signal to the vibration damping device for damping the vibration of the rotor.

Abstract: An additional mass member 22 for measuring resonance of a bearing device comprises an elastic ring 30 having an inner periphery 30a larger in diameter than the outer periphery of the outer ring 24 of the bearing device 25 and being contracted and expanded in the radial direction, and a fixed ring 31 having a large rigidity and fitted onto the elastic ring 30. The elastic ring 30 is fitted to the outer ring 20, and then the fixed ring 31 is fitted to the elastic ring 30 to push the elastic ring 30 in the radial direction, so as to contract the inner periphery 30a of the elastic ring 30, so that the additional mass member 22 is fixed to the bearing device 21, whereby the resonance frequency of the bearing device having a double row of bearings can be measured precisely and readily.

Abstract: A method is disclosed for evaluating a damaged blade in a compressor or turbine using a computer system accessing a database of blade repair information, where the method includes: selecting a blade damage geometry category corresponding to the damage of the blade from a plurality of blade damage geometry categories; measuring the blade damage, and generating a repair geometry for the blade based on the blade damage measurements and the selected blade damage geometry category.

Abstract: Computer-based method and system are provided for establishing operational stability prior to determining temperature correction factors for a generator. The method allows providing (e.g., 102) a data file including data indicative of prescribed stability criteria for the generator. The method further allows monitoring (e.g., 104) respective operational parameters indicative of actual operational stability of the generator. The respective operational parameters indicative of the actual operational stability of the generator are related (e.g., 106) to the prescribed stability criteria in the data file. In response to the relating action, a graphical display (e.g., 82) is generated (e.g., 108) and the graphical display is indicative of whether or not the actual operational stability of the generator complies with the prescribed stability criteria.

Abstract: A method and device for detection of a pulsed mechanical effect on a plant component includes continuously recording an operating noise in the plant component with a sensor disposed on the plant component and converting the recorded noise into a measured signal with the sensor. Then, the measured signal is subjected to a Fourier transformation. An evaluation function is derived from a number of value spectra determined in the above manner, which gives the onset of a pulsed mechanical effect on the plant component.

Abstract: An output signal that accords with a rotation speed of a brake rotor of a respective wheel is output by a vehicle wheel speed sensor. A noise frequency identification portion identifies a frequency component that corresponds to brake noise from this output signal. It is possible, for example, to identify a frequency component that corresponds to brake squeal by performing fast Fourier transform (FFT) calculation for the vehicle wheel speed. Further, a noise detection portion determines that brake noise is being generated when the frequency component identified by the noise frequency identification portion is equal to or more than a predetermined value.

Abstract: A method and apparatus for sensing and measuring stress waves. The method comprises the steps of: a.) sensing motion, where the motion comprises a stress wave component and a vibration component; b.) separating the stress wave component from the vibration component with a high pass filter to create a signal proportional to the stress wave; c.) amplifying the signal to create an amplified signal; d.) processing the amplified signal with a sample and hold peak detector over a predetermined interval of time to determine peaks of the amplified signal over said predetermined period of time; e.) creating an output signal proportional to the determined peaks of the amplified signal; and, f.) repeating steps d.) and e.). The invention also includes an apparatus for implementing the method of the invention.

Abstract: A system and method of directly, dynamically and on-line measuring different parameters related to the volume dynamically occupied by the internal load of rotating mills when in operation; specifically, an on-line measurement of the total dynamic volumetric load filling, dynamic volumetric ball load, dynamic volumetric mineral filling and of the apparent density of the internal load of the mill. The present invention comprises a series of wireless acoustic sensors attached to the mill's outer body, a receiving and/or conditioning unit located near the mill, a processing unit and a communication unit.

Abstract: A system for monitoring mechanical waves from a machine which in operation has moving particulate matter therein, the system including at least one sensor located on the machine at a location away from the central axis of the machine, the sensors being for sensing acoustic waves and including a transmitter for transmitting signals representing the sensed mechanical waves to a receiver at a location remote from the sensor(s), a data processor connected to the receiver for receiving signals from the receiver which signals represent the mechanical waves and processing the signals to produce output signals for display on a display means, wherein the output signals for display represent one or more parameters indicative of mechanical waves emitted from the machine over a predetermined period of time.

Abstract: A data collector having an integrated laser tachometer. The data collector includes, within a housing that can be held by a single hand, circuitry for receiving a vibration signal to be digitized, as well as an optical system for receiving light from outside said housing to be converted to a digital tachometer signal. Digital signal processing circuits within the housing receive, store or process the digitized vibration signal and/or the digital tachometer signal, for the purpose of predictive maintenance. The housing of the data collector also holds a display and input keys, so that an operator may use the same hand for holding and controlling the data collector, and for holding the integrated laser tachometer. This frees a hand for holding an accelerometer or for other purposes. Use of a data collector with an integrated laser tachometer is thus substantially more convenient than using a data collector with a separate, nonintegrated laser tachometer attachment.

Abstract: Object of this invention is to provide an axial torsional vibration measurement device of the reactor internal pump capable of measuring the axial torsional vibration easily. The vibration detector 2 that detects vibration in the radial direction, and the sound detector 3 that detects vibration in the circumferential direction are fitted on cylindrical motor casing 6, which contains the motor of a reactor internal pump. The dimension of both signals of a vibration waveform signal detected by the vibration detector 2, and a sound waveform signal detected by the sound detector 3 are matched in vibration calculating device 15, to thereby obtain an axial torsion vibration of a motor from the difference of both signals.

Abstract: The present invention is for a system (11) or method for conditioned based monitoring of a bearing assembly. The system (11) comprises a sensor (13) placed in proximity to a bearing assembly (12). The sensor (13) generates a signal indicative of the amplitude and frequency of the vibrational movement of the bearing assembly. A process (14) in communication with the sensor (13) receives the signal from the sensor (13) and generates spectral data representative of the bearing vibrational movement. A database (15) comprises data representative of an amplitude threshold, for at least one predetermined frequency, characteristic of a bearing fault. The processor (15) compares the spectral data to the amplitude threshold and generates a signal indication of the bearing assembly.

Abstract: System and method for analyzing an input signal acquired from a physical system with a rotating element. A tachometer signal is received comprising rotation speed information for the rotating element. A time sequence is determined using the tachometer signal, comprising time values for the rotating element at substantially equal angle increments, e.g., by edge detection software or timer/counter. A software-based first digital interpolation filter, e.g., a Cascade-Integrator-Comb filter, is applied to the time sequence, generating a modified time sequence. A digitized data signal is received comprising data for the rotating element at substantially equal time increments.