Abstract: Embodiments of high-resolution optical encoders having phased-array photodetectors and integrated on semiconductor chips. Emitters, detectors, and encoders disks are described which can be easily produced with semiconductor processes, such as a detector array provided with lens to collimate light and enhance detection. Integrated sensor chips include an array of photodetectors that receive energy from a beam emitted from an emitter and modulated by an encoder disk, analog-to-digital converters, state machines, counters, a communication module, a sensor processing unit, and a force computation unit. One embodiment includes low resolution and high resolution modes and an emitter controlled by sensor circuitry. A detector for an optical encoder can be provided on a single chip that includes a first array of photodetectors used for absolute sensing of a moving object, and a second array of photodetectors used for incremental sensing of the moving object.

Abstract: A method and apparatus for measuring the torque transmitted by a member comprises a SAW device (66) secured to the member such that mechanical stress in the member due to torque transmitted thereby induces bending of the SAW device. Means are provided for measuring the change in resonant frequency of the SAW device induced by bending. In one embodiment, a hole (52) is formed in the member (50) and the SAW device is mounted in a pair of diametrically opposite slots provided in the hole (52). The SAW device comprises a substrate on which electrode pairs are laid down, the electrode pairs being in a position such that bending of the SAW device results in compression of the zone containing one electrode pair and tension in a zone comprising another electrode pair. In an alternative arrangement the member is formed with a recessed portion in the surface thereof and the SAW device is mounted in a pair of slots formed by opposite walls of the recess.

Abstract: A contactless precision, optical distance and angle measurement method and system optically measuring the position of a moveable object, the bending of the object, the torque applied to the object and the object's rotational velocity. The present invention includes a plurality of optical sensors placed around and adjacent to the moveable object which transmit optical signals to a surface of the object and receives the optic signals when predefined marker means are sensed. The received optic signals are then processed by non-linear estimation techniques known to those of skill in the art to obtain the desired information.

Abstract: An apparatus for determining the torsional stiffness of a shaft comprises a rigid frame having a collet for securing one end of the shaft to be measured the rigid frame. A second collet secures the opposite end of the shaft to an inertial weight, which is supported for rotation by a separate bearing so that the inertial weight introduces no axial load in the shaft being measured. The inertial weight has mounted to it a biaxial accelerometer, optical gate or other electronic means for measuring the torsional frequency of the shaft/weight combination. When the inertial weight is displaced from the initial static position and released, the inertial weight oscillates about its center of mass under the urging of the torsional stiffness of the shaft. A computer is programmed with the mass moment of inertia of the inertial weight and therefore is able to solve the differential equation of motion for the torsional spring constant of the shaft based on the frequency of oscillation.

Abstract: A medium feeding apparatus comprises a driving motor for moving a backup plate to press a medium against a pickup roller, piezoelectric elements for sensing slippage between the pickup roller and the medium which occurs while the roller rotates, and a controller for driving the driving motor to thereby vary a force for pressing the medium against the pickup roller, when the sensing means has sensed slippage between the pickup roller and the medium.

Abstract: An object is to enable accurate measurement of dynamic torsional characteristics of a damper assembly. A measuring device measures an angular speed (d&thgr;1/dt) of an input rotary member, an angular speed (d&thgr;2/dt) of an output rotary member and a torque (T1) transmitted to the input rotary member. A torsion angle (&thgr;) of a damper unit is calculated by integrating the angular speeds (d&thgr;1/dt) and (d&thgr;2/dt) of the input and output rotary members. A torque (T) acting on the damper unit is calculated by subtracting a product of an angular acceleration (d2&thgr;1/dt2) of the input rotary member calculated by differentiating the angular speed (d&thgr;1/dt) of the input rotary member and a moment of inertia (I1) of the input rotary member from the torque (T1) transmitted to the input rotary member.

Abstract: A vibration sensing device including a strip bearing a pattern of markings. The strip is caused to slide back and forth in front of a sensor as the result of vibration or displacement of an object to which either the strip or the sensor is attached. By varying the spacing between the markings on strip, the direction and approximate speed of the motion can be sensed by the frequency of the signal generated by movement of the pattern past the sensor and its rate of change. The vibration sensing device can be made to sense out of balance (OOB) or vibratory motion of a piece of equipment such as a washing machine, motor engine or other device during use or transport.

Abstract: A diagnostic driveline vibration analyzing tool for measuring and characterizing the torsional vibration of a rotating component such as a transmission output shaft in a vehicle driveline. An electronic control unit and sensor cooperate to measure speed fluctuations occurring between the passing of adjacent teeth of a rotating gear. These time measurements are then filtered using an order tracked pass band filter to isolate frequencies of interest the results of which are then used to calculate a total torsional energy level by taking the root mean square of the filtered signal over a predetermined period of time. The total torsional energy level is then compared to a predetermined maximum amplitude and if the total torsional level exceeds this predetermined maximum amplitude then the operator is notified through a display device.

Abstract: An apparatus for testing the damping force of vibration dampers includes a frame, a drive and a clamping device for receiving the vibration dampers. One part of the clamping device is fixed in place and the other part is axially movable. The axially movable part of the clamping device is connected to the drive with a force transducer and a drive element. The drive is controlled by a control system.

Abstract: An impact sensing system senses an impact or acceleration applied and provides an external alarm indicative of the impact or acceleration applied. An envelope detector detects an envelope of an output signal of said sensor unit. An amplifier amplifies the output signal of said envelope detector, a direct current component being eliminated therefrom. A first low pass filter filters a first level signal from the output signal of said amplifier, the first level signal being indicative of a first level of impact or acceleration. A second low pass filter filters a second level signal from the output signal of said amplifier, the second level signal being indicative of a second level of impact or acceleration. A first timing pulse generator generates a first timing pulse with a first time duration in response to the output signal of said first low pass filter, the first time duration being indicative of said first level signal.

Abstract: An operating parameter of a centrifuge is determined by converting vibration of the machine frame of the centrifuge on rotation of the drum thereof to electrical signals having a frequency spectrum which is analyzed. Variations of the peak amplitudes and frequency locations on frequency analysis, e.g. by Fast Fourier Transmissions, is used to signal the parameter, e.g. a parameter representing the degrees of filling the centrifuge, termination of filtration, etc.

Abstract: A system detects relative movement between an optical sensor unit and a set of finely spaced, parallel grid lines. Unlike prior optical line detection systems, each set of lines is applied to a surface of an object at an angle relative to movement between the optical sensor unit and the object. The system is particularly useful for monitoring rotating members, such as shafts, but is also useful with linearly moving members. In a preferred shaft monitoring application, a plurality of optical units are provided, with a plurality of corresponding sets of parallel lines at different angles on the shaft. Signal output phase differences between the optical units are compared to precisely determine movement of the shaft in seven directions of freedom, including rigid body displacement components along three translational and three rotational axes, and shaft twist.

Abstract: A method for measuring the torsional rigidity distribution of a shaft comprises the steps of; disposing a shaft to be measured in a vertical position in which the upper end thereof is immovably held and the lower end of the shaft is rotatable about the axis of the shaft, demarcating the shaft along its length so as to establish a number of discrete sections of the shaft, performing measurements of the torsional frequency of an inertial mass held at designated discrete positions shaft, and calculating the torsional rigidity of each discrete section based on the measured torsional frequencies.

Abstract: A method and device for processing encoder signals from turbomachines to produce frequency modulation signals representing fully isolated rotor vibrational resonances. Multi-sensor and multi-sideband group processing provides enhanced results. The method provides dramatically improved frequency resolution. Amplitude modulation and random noise effects are removed by a variety of artifact-free techniques. Signals then are completely separated into components for rotational vibration and translational vibration. Fully isolating rotational vibration unmasks previously undetectable signal components of diagnostic value. In cases of high background vibration, Wiener filtering removes the effects of exogenous vibration. By these various techniques, the present invention provides significantly enhanced diagnostic information regarding condition and performance in turbomachines.

Abstract: A structure of a magnetostrictive shaft applicable to a magnetostriction-type torque sensor and a method for manufacturing the same can achieve a high torque sensitivity. A shaft parent material is made of a non-magnetic austenitic series metallic material (YHD50) and a magnetic thin film is made of a magnetostriction material such as Iron-Aluminum series alloy plasma spray coated on the whole outer peripheral surface of the shaft parent material. In a second embodiment, a mechanical working is carried out for the shaft material on the surface of which the magnetostriction material thin film is coated, the worked shaft material is heated under an inert gas atmosphere, and the heated shaft material is immersed into oil under the inert gas atmosphere to perform oil quenching.

Abstract: A motor controller includes a shaft torsion vibration estimator for estimating a shaft torsion vibration between a motor and a mechanical load and a shaft torque estimator for estimating a shaft torque acting upon a motor shaft, wherein a vibration in a mechanical load driving system is suppressed by utilizing an estimated shaft torsion torque value calculated by the shaft torsion vibration estimator and an estimated shaft torque value calculated by the shaft torque estimator in addition to a detected motor speed value. Using such a system stable speed control having improved response can be achieved since higher order vibration modes can be suppressed without deteriorating its shaft torsion vibration without deteriorating its shaft torsion vibration suppression performance by combining the shaft torsion vibration estimator and the shaft torque estimator.

Abstract: Methods and apparatus for precisely applying finely spaced grid lines to an existing shaft on site include, in a first embodiment, attachment of a master grid line carrier to the shaft. In preferred embodiments, the carrier is helically wrapped about the shaft or mated at a diagonal seam across the carrier. Photosensitive material is then applied to the shaft at one or more axial locations. The shaft is rotated and passage of the grid lines on the master is sensed. A light source synchronized to the detection of the master grid lines exposes the photosensitive material as the shaft is rotated to create identical sets of finely spaced grid lines at multiple axial locations on the shaft. The invention also includes a synchronous laser Dopper velocimeter (SLDV) which accurately senses the passage of the lines on the shaft. An extremely accurate torsional interferometer can be constructed using the SLDVs.

Abstract: An apparatus for measuring torsional vibrations of rotating machinery is provided. A wheel having a plurality of spaced apart teeth is connected to the rotating machinery. A sensor detects the speed of wheel rotation and responsively produces a speed signal that has a frequency proportional to the rotational wheel speed. A timing device receives the speed signal, determines the period of the most recent pulse of the speed signal, and responsively produces an instantaneous period signal that has a value representative of the determined period. A microprocessor receives the instantaneous period signal, determines an instantaneous speed value of the rotating wheel and an average speed value of the rotating wheel based on previous wheel rotations.

Abstract: A shock and vibration detecting device comprising a sensor enclosed in an electromagnetic shielded and dust-proof case to send out a signal to an amplifying circuit constituted mainly by an operational amplifier once it picks up a shock and/or vibration signal. The output of the amplifying circuit is connected to a driving circuit to provide an output signal. A delaying circuit is used to lengthen the active period of the output signal. A voltage regulation circuit provides a regulated and filtered voltage to the above-mentioned circuits.

Abstract: An optical system for monitor vibration, particularly applicable to power shafts in rotating power systems such as those found in trucks, naval vessels, turbogenerators, hydroelectric and nuclear generators, and helicopters, has an optical unit including IRLED radiation sources aimed at grid lines applied around the circumference of the shaft. The reflection of the radiation is imaged through lenses and a matching Ronchi grid onto a photodiode which produces a periodic wave signal from which indications of rotational irregularities can be derived. In one embodiment, duplicate radiation sources and imaging apparatus are arranged in diametric opposition across the shaft to permit compensation for pitch and plunge shaft vibration. In another preferred embodiment, a second, duplicate optical unit is located at a distance along the shaft from the first unit.

Abstract: A vibration monitoring system operates down-hole in the bottom hole assembly above the drill bit. This system includes four spaced accelerometers which measure and differentiate between lateral, longitudinal and torsional drillstring vibrations. Three of the four accelerometers are in a cooperative spaced arrangement and measure tangential acceleration forces on the outer diameter of the drillstring for determining and measuring both lateral and torsional vibrations. The fourth accelerometer measures longitudinal vibration. Two embodiments are disclosed for arranging the three accelerometers which measure lateral and torsional vibration. In a first embodiment, the accelerometers are equi-spaced 120 degrees apart from one another. In a second embodiment, the three accelerometers are spaced 30 degrees apart from one another within a 60 degree arc. In both embodiments, all four accelerometers are positioned within the annular wall of a drill collar segment.

Abstract: An operating turbine monitor is described incorporating one or more acoustic sensors positioned next to a blade row of a rotor, an analog digital converter, a tachometer sensor at the rotor shaft, a memory, a synchronous averaging circuit, a subtractor circuit, and a comparator. The invention overcomes the problem of monitoring an operating turbine of order-related turbine blade vibration and for non order-related turbine blade vibration as well as for other turbine conditions.

Abstract: A load indicating member and load indicating fastener are disclosed and claimed. An ultrasonic transducer, grown on one surface of a load indicating member, such as a fastener, is used to determined the length, stress or other tensile load dependent characteristic of the member using ultrasonic techniques.

Abstract: Method and apparatus for non-destructive testing the quality of manufactured wood panels which includes supporting the panel so as to have a portion thereof in cantilevered fashion. The cantilevered portion of the panel is caused to vibrate so as to include complex vibrations that include both twisting and bending. The vibrations in the panel are sensed providing an output signal that is fed to analyzers and computers to determine from the simultaneously induced bending and twisting vibrations respectively the modulus of elasticity and shear modulus of the panel. Two different forms of apparatus are illustrated, one of which requires the panel to be stationary while being tested and the other in which the panel moves continuously while vibrations are induced and the induced vibrations sensed.

Abstract: Noise and vibration in a structure are reduced through application to the structure of an oscillatory torque. An electromechanical energy converter provides the oscillatory torque when the input signal to the electromechanical energy converter has a frequency and harmonics thereof required to counteract the noise and vibration desired to be attenuated.

Abstract: A nonintrusive method for determining the magnitudes and spatial and temporal origins of individual dynamic (time varying) torsion loads acting in superposition on a rotating shaft or system of shafts includes combining the measurements of said shaft's inertial response to the dynamic torsion loads with the measurements of discrete relative angular displacement parameters at causally connected space-time points. Changes in the shaft's characteristics, such as those due to change in its temperature or degradation of its structural integrity, can be monitored to provide updated torque determinations that maintain accuracy by taking these changes into account and to provide information on the onset and location of shaft fractures. Apparatus based on the method of this invention is self calibrating.

Abstract: The movement of a rotating part of a machine is monitored by deriving a signal representing the motion of the rotating part, at least temporarily storing the derived signal, and analyzing the stored signal, with temporary storage being performed only on portions of the signal derived during spaced time intervals during each revolution of the rotating part.

Abstract: A shaft torsion monitor comprises a plurality of sensors for sensing the angular position of various portions of the shaft under dynamic conditions and for producing sets of data representative of the sensed angular positions. A memory is provided for periodically storing one of the sets of data representative of the angular position of the various portions of the shaft in the absence of torsion. Circuitry is provided for subtracting the stored set of data from each of the other sets of data to eliminate the effects of noise. The resulting data is analyzed to determine the torsion experienced by the shaft.

Abstract: A shaft torsional vibration monitor for a poly phase turbine generator and its prime mover turbine connected thereto comprises an electrical torque detector detecting electromagnetic torque applied to the turbine generator rotor, a memory unit capable of storing plurality sets of torque variation data due to system disturbances each having an initial torque variation rate more than a predetermined amount, a first processor fetching the sets of torque variation data one by one from the memory unit and determining the corresponding shaft torsional vibration and a second processor determining fatigue and life expectancy of the rotary shaft system for the turbine generator and its turbine by accumulating torsional stresses caused by respective shaft torsional vibrations.

Abstract: Apparatus and method for detecting torsional vibrations of the shaft of an exciter of a turbine-generator, according to which a permanent magnet generator is connected to be driven by the exciter shaft and has an electrical output for providing an output voltage having a frequency proportional to the rate of rotation of the exciter shaft; and the electrical output is connected to signal processing circuitry serving to derive a signal representative of torsional vibrations experienced by the exciter shaft.

Abstract: The preferred arrangement utilizes a magnet suspended at the center of an elastic cord over a pickup coil. Movement of the magnet is sensed by the coil in that signals are generated by such movement. The signals are processed in the combination of a time delay circuit and a comparator to provide an output which is a measure of acceleration of the element on which the elastic cord is mounted and, in one form, by a measure of jerk in a similar time delay circuit and comparator combination.

Abstract: A circuit for damping hunting oscillations of controlled electric machines. The circuit is provided with a measuring circuit for determining the hunting oscillations and an identifier circuit for determining the angle components of such hunting oscillations. A phase shifter circuit is provided for receiving the angle components produced by the identifier circuit and forming a hunting oscillation correction signal which is shifted in phase from the hunting oscillations by a predetermined phase angle. The hunting oscillation correction signal is conducted to a control unit of the electric machine. The invention is particularly useful in damping hunting by the rotors of voltage controlled synchronous generators.

Abstract: An integrated closed loop engine control is disclosed in which the fuel delivery and timing functions of the engine are closed about a measurement of the engine's instantaneous rotational velocity. Signals indicative of the profile of each torque impulse imparted to rotary output member of the engine from the burning of an air/fuel mix in the engine's combustion chambers are generated and electrically analyzed to detect perturbation caused by deviations of at least two different engine operational parameters from desired values. Feedback correction signals indicative of the magnitude of the detected perturbations are generated to correct the fuel delivery and timing functions of an engine control to minimize the difference between the actual operating parameters and the desired values.

Abstract: An improvement in torsional vibration monitors wherein a frequency shift is applied to the torsional vibration signal to achieve improved stability and increased confidence in the measurement. The torsional vibration signal is applied to parallel frequency shifters to produce a lower frequency measuring signal and a lower frequency reference signal. The two lower frequency signals are applied to parallel connected filters to obtain spectral content of the signals. Once the spectral content is obtained, each lower frequency measuring signal and each lower frequency reference signal is shifted back to the original frequency range to produce filtered reference signals and filtered measuring signals. These signals are then correspondingly summed to provide a set of torsional vibration signals segregated with respect to the frequency spectrum and meaningful with respect to a time base.

Abstract: An apparatus for monitoring torsional vibrations of a rotating shaft system such as for a turbine generator in which torsional vibrations at certain positions of the rotating shaft system are detected by detectors and the detected vibrations are converted into torsional vibration at an arbitrary position of the rotating shaft system by using an operation device having desired transfer characteristics, said arbitrary position is monitored on torsional vibration on the basis of the converted torsional vibration.

Abstract: This invention concerns apparatus for reliably estimating the strain on an inaccessible portion of a shaft of a turbine generator system which is susceptible to torsional oscillation. The strain is continuously predicted on a real time basis as a function of the modal analysis parameters of the shaft. Furthermore, system torque is detected electrically at the output of the generator. This signal along with signals representative of shaft angular velocity at the easily accessible ends thereof is provided to the modal analysis means as inputs. The provision of these latter system data allow for the elimination of an equal number of unknowns in the modal analysis representation, thus reducing the complexity of the analyzing system and increasing the reliability.

Abstract: The disclosed torsional vibration monitoring apparatus estimates torsional vibration at arbitrary positions in a shaft system, such as in a turbine generator. Detectors detect torsional vibrations produced at fixed positions of the rotating shaft system and the detected vibrations are separated into modal vibrations so that subtractors and matrix operators can obtain up to n vibration mode components from the modal vibrations and the torsional vibrations detected. First modal vibration operators obtain modal vibrations higher than the (n+1)th modal vibrations at the arbitrary positions of the rotating shaft system from the detected torsional vibrations, second modal operators obtain up to the n-th modal vibrations at the arbitrary positions from the vibration mode components and adders add the respective modal vibrations obtained by the first and second modal operators.

Abstract: The disclosed torsional vibration monitoring method measures torsional vibrations produced in a rotating shaft system, for apparatuses such as a turbine generator, at a small number of measurable points on the system and the measured torsional vibrations are linearly separated to estimate torsional vibrations at arbitrary positions of the system are estimated. According to one high precision torsional vibration monitoring method, up to 2n torsional vibrations at the arbitrary positions are obtained from the torsional vibrations detected at n selected positions of the rotating shaft system.

Abstract: The present invention relates to a torsional vibration monitoring apparatus for a rotating shaft system which is characterized by comprising a detector disposed at a certain position of the rotating shaft system for detecting torsional vibration of the shaft system, a memory device for storing the torsional vibration having a constant time duration which is detected by the detector as a time series data obtained by sampling the torsional vibration with minute unit times, a Fourier transforming device for Fourier-transforming the time series data to obtain a frequency series data, multiplier each for multiplying the frequency series data with a relation which is previously obtained between the vibration of the shaft system at the certain position of the shaft system and that at an arbitrary position thereof at respective frequencies to obtain a frequency series data for the arbitrary position, and reverse Fourier transformer for reverse-Fourier-transforming the frequency series data to obtain a time series dat

Abstract: The present invention is a torsional vibration monitoring method and an apparatus for performing the same, in which torsional vibrations produced in a rotating shaft system for use in such as a turbine generator are measured at a small number of certain positions therealong at which the measurements are possible, the torsional vibrations are linearly decomposed and torsional vibrations at arbitrary positions on the rotating shaft system are estimated from the linear decompositions.

Abstract: A vortex-shedding flowmeter in which a liquid or gas to be metered is conducted through a flow tube having a shedding body transversely supported thereon. Torsionally-supported at a downstream position behind the shedder on a shaft which projects outside of the flow tube to provide a shaft extension is a sensor, the pivot axis of the shaft being normal to the longitudinal axis of the tube. In operation, as the incoming fluid stream is divided by and flows past the shedder, vortices are successively detached therefrom and appear alternately on either side of the sensor, thereby developing a torque about the pivot axis. The torques are developed alternately in the clockwise and counterclockwise directions, causing the torsionally-supported sensor to oscillate at a rate proportional to the flow rate of the fluid. These oscillations are converted by a transducer operatively coupled to the sensor into a corresponding electrical signal.

Abstract: A system applicable to rotary drilling. It includes a torque meter that measures dynamic torque while drilling. The system averages the time period of individual oscillations in the torque, for a given number of such oscillations. It indicates the length of such average time numerically. Consequently, the probable cause of the oscillations may be inferred.

Abstract: A device is provided for measuring the torsional acceleration of a rotating body, and particularly for measurement of oscillatory torques such as the starting torque of a synchronous motor. The device consists of two identical accelerometers mounted on a rotating body at equal radii 180.degree. apart, and oriented so as to be insensitive to the outwardly directed radial forces present during acceleration.

Abstract: A method and apparatus are provided for measuring torsional vibrations of a rotating member by sensing passage of a plurality of circumferentially spaced elements adapted for movement with the member and for producing an electrical signal including true components representing the torsional vibrations and from which selected false components representing inhomogeneities in the elements have been eliminated.

Abstract: Apparatus is described for monitoring phase currents and torsional vibrations of a turbine-generator which are indicative of the dynamic response of the machine during operation under load. The monitoring system disclosed includes probes which are operable to sense rotation of the main shaft of the turbine-generator and to feed the resulting signals to a vibration network. The vibration network eliminates from the signals any false components present at frequencies equal to multiples of the rate of rotation of the shaft and produces a composite vibration signal containing only true components of shaft torsional vibration. The composite vibration signal and a set of three phase current signals determined by stepping down, filtering, and amplifying the generator line currents are monitored continuously but recorded only when at least one of two signals derived from selected components of the composite vibration signal and phase current signals exceeds reference levels in an alarm system included in the monitor.

Abstract: An alarm system is disclosed for generating alarms when torsional oscillations of a rotating shaft exceed predetermined limits and fail to subside at a predetermined rate. The alarm system receives a torsional oscillation input signal developed by measuring the deviation of instantaneous shaft angle from a uniformly increasing value. The input signal is converted to a direct current torsional oscillation signal representative of the magnitude of oscillation. The torsional oscillation signal is compared against a first adjustable reference voltage representative of a first maximum magnitude of oscillation. A low level alarm signal is generated when the oscillation signal exceeds the first reference voltage for a predetermined length of time. The oscillation signal is also compared against a second reference voltage representative of a second maximum magnitude of oscillation. An output signal is generated when the oscillation signal exceeds the second reference voltage.

Abstract: The fuel injection control pulses of an internal combustion engine may be shortened or lengthened to provide operation of the engine at a definite fuel-air ratio. When operation takes place in a leaned-out region, the engine suffers dynamic instability, resulting in rapid fluctuations of the rotational crankshaft velocity, superimposed on regular, periodic changes due to compression changes.The crankshaft speed is tested at two different locations of the angular path by passing markers in front of an inductive transducer. The output signal from this transducer gates the counting input of a digital counter which is supplied with a pulse train at a constant, high frequency. A flip-flop alternately causes upward and downward counting in the counter so that a net difference of counted pulses is formed after each two successive counting periods.

Abstract: A roughness sensor for measuring cycle-to-cycle decreases in engine speed comprises engine-event responsive flip flop means for controlling the alternate store-up and subsequent count-down of contents into a first storage means simultaneously with the alternate count-down and the store-up of contents into a second storage means. The storage means feed respective first and second comparators that produce respective first and second output pulses the widths of which are determined by the interval between the time a corresponding storage means is counted down to its starting value and the time of the next flip flop transition. A raw roughness output pulse in the form of just one but not both or neither comparator output pulses is passed by exclusive OR logic means to a speed normalization means that also receives the contents of the storage means opposite to that producing the raw roughness pulse.