1237 results about "Low frequency vibration" patented technology

An emergency system for treatment of a patient (20) experiencing an acute vascular obstruction, employing a non-invasive vibrator (10), optimally in conjunction with drugs, for disrupting and lysing thromboses, relieving spasm (if associated), and thereby restoring blood perfusion. Vibrator (10) is operable in the sonic to infrasonic range, with a source output of up to 15 mm. For acute myocardial infarction cases, a pair of contacts (12), are advantageously placed to bridge the sternum at the fourth intercostal space. Vibration is initiated at 50 Hz (or any frequency, preferably within the 20-120 Hz range), and is ideally adjusted to a maximal amplitude (or force) deemed tolerable and safe to the patient (20), preferably with the administration of thrombolytic agents or other form of drug therapy. A synergistic effect is achieved between vibration and drugs to facilitate the disruption of thromboses, relieve spasm, and restore blood perfusion. In a variation, ultrasonic imaging may be used to direct vibration therapy.

Electromagnetic motor with a piston that moves linearly with respect to the stator in either direction. Embodiments include a piston internal or external the stator. The piston includes one or more magnetic flux producing elements in all embodiments, with some embodiments having a ferro-magnetic plate on either side of the flux producing element. Further, in all embodiments the stator includes three magnetic flux producing elements with either two coils with one or more magnets therebetween or with the two coils and a coil magnet substitute therebetween. All embodiments provide positive piston return to a center at rest position. In all embodiments the piston is centered with respect to the stator resulting from either magnetic interaction between the piston and stator magnets, or between the piston magnet and the stator magnet substitute coil.

Electromagnetic motor with a slider that moves linearly with respect to the stator in either direction. Embodiments include slider internal or external the stator. Slider includes one magnetic flux producing element in all embodiments. Internal slider embodiments stator includes a minimum of three magnetic flux producing elements and a maximum of four such elements. External slider embodiments stator includes two magnetic flux producing elements. All embodiments provide positive slider return to center at rest position. In internal slider embodiments the slider is centered within the stator resulting from either: a combination of a repelling force from a single magnetic flux producing element in opposition to gravitational pull on the slider due to its weight; or equal and opposite repelling forces on opposite sides of the stator from a magnetic flux producing element on opposite sides of the stator all three elements in longitudinal alignment with each other.

Electromagnetic motor with a slider that moves linearly with respect to the stator in either direction. Embodiments include slider internal or external the stator. Slider includes one magnetic flux producing element in all embodiments. Internal slider embodiments stator includes a minimum of three magnetic flux producing elements and a maximum of four such elements. External slider embodiments stator includes two magnetic flux producing elements. All embodiments provide positive slider return to center at rest position. In internal slider embodiments the slider is centered within the stator resulting from either: a combination of a repelling force from a single magnetic flux producing element in opposition to gravitational pull on the slider due to its weight; or equal and opposite repelling forces on opposite sides of the stator from a magnetic flux producing element on opposite sides of the stator all three elements in longitudinal alignment with each other.

The invention discloses a three-degree-of-freedom aerial photographic head with the stable inertia, which comprises a stabilizer, a transmission device and a camera. The three-degree-of-freedom aerial photographic head with the stable inertia adopts a main principle that a mechanical gyro with the considerable inertia realizes stable shooting. A head bracket is connected with a horizontal rotating rack; the horizontal rotating rack is connected with the mechanical gyro to form the stabilizer; and the stabilizer is connected with the camera through the transmission device, so the synchronous movement of the gyro and the camera in the vertical direction can be realized and the stable shooting of the camera can be realized by the stability of the gyro. The three-degree-of-freedom aerial photographic head with the stable inertia can eliminate the influence of the high-frequency and low-frequency vibration of a plane on the aerial photographic images and the problem of image inclination which is caused by the inclination of the plane, can photograph very clear and stable images without any chattering removal treatment and has good application effects in aspects of line detection, fixed-point monitoring, aerial photograph and the like. The three-degree-of-freedom aerial photographic head with the stable inertia has novel design and strong stability and can meet requirements on most high-quality aerial photographs.

A miniaturized, ruggedized, field-deployable Portable Exposure Assessment System (PEAS) is used to remotely monitor workers and provide real-time warning of exposure to musculoskeletal injury conditions via alarm and smart-phone transmission. The PEAS unit wirelessly acquires exposure data from sensors; conducts initial data analysis; triggers proximal and remote alarms; sends out text messages with abnormal data, GPS locations, and time stamps to a safety office; and saves data for more extensive assessment. Sensor technology is used in this field-deployable system to simultaneously measure and collect the body loads and awkward postures imposed by package handling as well as driving-related, low-frequency vibration exposures. Wireless technology is used to set up wireless communication links between the sensors and a data logger and between the data logger and a smart phone with GPS, date / time stamp and text messaging capabilities.

The invention relates to a method and a device for the ultrasonic and nondestructive detection of the elasticity of a viscoelastic medium, which belong to the technical field of nondestructive measurements. The method comprises the following steps of: using an ultrasonic probe to produce low-frequency vibration on a medium to be detected, emitting ultrasonic waves to the medium to be detected and acquiring an ultrasonic signal returned from the medium to be detected; selecting an ultrasonic signal range for calculating the elasticity of the medium to be detected; using the selected ultrasonic signal to calculate the transmission speed of an elastic wave produced by the low-frequency vibration in the medium and further calculating the medium elasticity according to the obtained transmission speed of the elastic wave. The device comprises an ultrasonic wave energy converter contact, a vibrator fixing the ultrasonic wave energy converter contact and a control device. In the method and device, motion compensation of the ultrasonic probe is not required, so that calculation time is shortened; meanwhile, position detection is carry out without a position sensor, so that the system complexity and cost are lowered.

The invention discloses a parallel mechanism based multidimensional vibration platform. Standard zero stiffness of a vibration isolation platform at the equilibrium position and nonlinear stiffness nearby the equilibrium position can be realized by setting certain structural parameters, and the problem about difficulty in isolating low-frequency or ultra-low-frequency vibration for a traditional linear vibration isolation system; stiffness and damping can be easily and conveniently adjusted, vibration isolation of broad frequency domains are satisfied, and good engineering applicability is achieved; the multidimensional vibration platform is high in bearing stiffness, low in movement stiffness, small in static deflection, low in dynamic inherent frequency and good in vibration isolation effect; inherent contradictions restricting the traditional vibration isolation system, namely the contradictions of low-frequency vibration transmissibility and high-frequency vibration attenuation, can be solved by flexible adjustment of the stiffness and damping; the height and the static equilibrium position of the entire platform can be changed by adjusting a shock absorber spring base in height, and the multidimensional vibration platform is applicable to vibration isolation of objects of different weight.

A method and a micro power generator for generating electrical power from low frequency, vibrational energy includes a frequency up-conversion process. The generator is preferably an electromagnetic, vibration-to-electrical power generator which can efficiently scavenge energy from low frequency external vibrations. The generator up-converts low frequency environmental vibrations to a much higher frequency through a mechanical frequency up-converter, and hence provides efficient energy conversion even at low frequencies. This mechanical frequency up-conversion process can be realized in a number of ways. A magnetic method is described as an example. After frequency up-conversion, voltage is induced on coils mounted on resonators by electromagnetic induction. Due to the movement of the coils on their respective resonating cantilevers with respect to the magnet, voltage is generated on the coils and energy conversion is realized.

A therapeutic device and method for use thereof for treatment of blood flow disorders is disclosed. In one embodiment, a first line emergency response system for treatment of acute thrombotic and / or vasospastic vascular obstructions via the noninvasive application of low frequency vibration with at least one, and preferably a plurality of randomly administered vibratory waveform characteristics (herein after “Randomic Vibration”) is detailed. The disclosed apparatus and methods are based on the intuition that transcutaneously imparted low frequency randomic vibration can provide enhanced clot disruption and mixing of clot disruptive agents to acutely thrombosed vessels, due to the addition of mechanical chaos via non-regular, multi-vectored convection currents. In a preferred embodiment, the disclosed apparatus and methods preferably utilize randomic vibration as an adjunct to systemically administered drug therapy, most preferably intravenously administered thrombolytic drug therapy.

An apparatus for use in low frequency vibration energy harvesting (VEH) and with actuators requiring a low deflection force. The apparatus includes a piezo flexure that is loaded with a compressive pre-load force to place the piezo flexure under compression. The piezo flexure may be supported at an intermediate point or at one end thereof. The compressive pre-load force produces flexes the piezo flexure into one or the other of two stable positions, these positions being offset on opposite sides of a longitudinal centerline representing the position of the piezo flexure that would be produced without the compressive pre-load force applied thereto. The compressive pre-load effectively provides a negative spring constant which “softens” the piezo flexure and enhances a responsiveness of the piezo flexure to low frequency vibration energy. The piezo flexure also operates over a much wider frequency bandwidth than conventional systems incorporating a tip mass.

The invention discloses a load-bearing adjustable zero-stiffness electromagnetic vibration isolator and a control method thereof. An electromagnetic spring of the vibration isolator in the perpendicular direction is composed of three permanent magnets and two groups of controllable direct current electromagnets, two magnets have opposite polarity and generate repulsive force, and stiffness of theelectromagnetic spring can be adjusted by changing and controlling current. An electromagnetic spring of the vibration isolator in the horizontal direction is composed of two groups of symmetrically distributed electromagnetic springs, and stiffness of the electromagnetic spring can be adjusted by changing and controlling current. When the system load-bearing weight is changed, the stiffness of the perpendicular electromagnetic spring and the stiffness of the horizontal electromagnetic spring are led to meet a certain proportional relationship by adjusting and controlling current so that stiffness of the system at the balance position can be zero. When a vibration isolation device is in small vibration near the balance position, dynamic stiffness is very small, and natural frequency of the whole system is very low so that the vibration isolator can achieve wide-range frequency vibration isolation and has good low frequency vibration isolation effect. In addition, the vibration isolator is compact in structure, light in weight and convenient to control.

A virtual reality ride system including a headset, a control unit, and a dynamic platform. The headset includes a display unit configured to display a video of an animated virtual environment. The control unit includes one or more processors configured to perform render processing that renders the video of the virtual environment; event motion processing that generates first data representing motions associated with events in the virtual environment; and low-frequency motion processing that generates second data representing low-frequency vibrations unrelated to the events in the virtual environment. The dynamic platform is configured to produce the motions associated with the events in the virtual environment based on the first data, and to produce the low-frequency vibrations based on the second data. The low-frequency vibrations include a frequency between about 5 Hz and 70 Hz.

The invention belongs to the technical field of vibration and noise control and relates to a relatively-high-applicability passive isolation technology for ultralow-frequency vibration. In order to effectively solve the problem between the low-frequency vibration transmissibility and the high-frequency vibration attenuation rate of the vibration isolator, the invention provides the stiffness-adjustable magnetic vibration isolator with quasi zero stiffness, which adopts rectangular permanent magnets generating negative stiffness and an elastic capsule providing positive stiffness; and when a load is changed, the working position of the elastic capsule is controlled unchanged, the positive stiffness of the elastic capsule is changed because the pressure inside the elastic capsule is changed, and then, the negative stiffness is matched with the positive stiffness through regulating the distance among the rectangular magnets, so that the stiffness-adjustable magnetic vibration isolator with quasi zero stiffness is adaptable to vibration isolation objects with different weights. The stiffness-adjustable magnetic vibration isolator with quasi zero stiffness is simple in structure, convenient to mount, adjustable in bearing capacity, excellent in vibration isolation property, compact in structure, light in weight and suitable for popularization and application.

A fat remover is disclosed, which comprises an upper main body including a plurality of connection terminals, a lower main body including an upper plate having a plurality of female rivets transmitting ultrasonic signals and low-frequency signals by contact with the connection terminals, a cup body having an opened bottom surface, a rubber plate interposed between the upper plate and the cup body, and a second lower plate inserted in the bottom surface of the cup body, and a skin contact sensor protruded on an inner lower part of the lower main body together with the ultrasonic vibration plate and the low-frequency vibration plate. Accordingly, the fat remover separately has the ultrasonic vibration plate and the low-frequency vibration plate, and performs fat removal after confirming a close contact between the skin and the vibration plates by the skin contact sensor, by applying stimulus to the skin contacting the vibration plates.

The invention relates to a device and a method for detecting pipeline closed cracks based on the vibro-acoustic modulation technology and belongs to the pipeline nondestructive testing field. The device provided by the invention comprises a computer, a first function generator, a second function generator, a first power amplifier, a second power amplifier, a vibration exciter, an accelerometer, acharge amplifier, a first thickness concertina-type piezoelectric ceramic sheet array and a second thickness concertina-type piezoelectric ceramic sheet array, an anti-aliasing filter and a data collection card. The method provided by the invention comprises the following steps of: acquiring a pipeline first-order bending vibration inherent frequency by swept frequency excitation; taking the frequency as the one of low-frequency vibration in the vibro-acoustic modulation detection; simultaneously exciting low-frequency bending vibration and high-frequency supersonic waves into the pipeline, determining whether there exists closed cracks inside the pipeline by the existence of frequency components which equal high frequency supersonic wave frequency subtracts or adds low frequency bending vibration frequency in a received signal frequency spectrogram. The device provided by the invention is utilized to solve the problem that it is hard to detect closed cracks by traditional methods, and can be applied to detect closed cracks in industrial pipelines.

The invention discloses a vibration sensor and audio equipment. The vibration sensor comprises a shell which is provided with an accommodating cavity with an opening; a circuit board component that isfixedly connected with the shell and blocks the opening; an MEMS microphone that is arranged on one surface of the circuit board component, positioned in the accommodating cavity, and electrically connected with the circuit board component; a first vibration film that is arranged on the inner wall surface of the accommodating cavity; a mass block that is fit with the surface of the first vibration film, wherein when a vibration signal or a pressure signal is input from one side, far away from the accommodating cavity, of the shell, the first vibration film and the mass block vibrate, so as todrive the air pressure in the accommodating cavity to change. The technical scheme provided by the invention aims at enabling the vibration sensor to have good vibration response to high frequency vibration and low frequency vibration, and thus the effect of the vibration sensor applied to the audio field is enhanced.

The invention discloses a symmetric rotation piezoelectric generation device which belongs to the technical field of micro energy and is particularly suitable for collecting varying rotation mechanical energy in a low-frequency vibration environment. The generation device consists of a rotation shaft, left and right bases, left and right bearings, left and right piezoelectric bi-crystal beam arrays, an excitation wheel permanent magnet array and an excitation wheel. The excitation wheel is in rigid connection with the rotation shaft; and the rotation shaft is supported in the center holes of the left and the right bases by the left and the right bearings respectively. In the generation device, the left and the right piezoelectric bi-crystal beam arrays are completely symmetric in structure. The excitation wheel permanent magnet array consisting of multiple excitation wheel permanent magnets is uniformly arranged at the periphery of the left side of the excitation wheel; each piezoelectric bi-crystal beam is composed of a permanent magnet block, a copper beam and a piezoelectric ceramic chip; and the piezoelectric bi-crystal beam array consisting of the left and the right piezoelectric bi-crystal beams is uniformly mounted on the left and the right bases. The device transfers the acting force by use of non-contact permanent magnetic force, thereby avoiding the energy loss and service life reduction caused by mechanical impact, and increasing the response bandwidth of a common rotation piezoelectric generation device.

The invention provides a method for monitoring low-frequency vibration of a wind power generation set. The method includes the following steps of acquiring set vibration signals of the wind power generation set by an acceleration sensor, processing the set vibration signals correspondingly by a filter and a wave detector in a vibration analyzer to acquire various low-frequency vibration monitoring signals, transmitting the monitoring signals to a PLC (programmable logic controller) of a wind power generation set control cabinet, and comparing threshold values, corresponding to the various monitoring signals, of an alarm threshold curve in the PLC so that the PLC can process fault alarms or fault halts according to compared trigger conditions. The method for monitoring low-frequency vibration of the wind power generation set has the advantages that resonance of a tower and blades of the wind power generation set can be effectively and accurately solved, and faults caused by other low-frequency vibrations in safety impact monitoring, driving chain vibration and engine framework can be further effectively and accurately solved.

The invention discloses a multi-channel synchronous vibration data collecting system which comprises signal front-end processing modules, a singlechip integration control module, a data communication module and a collection computer; two signal front-end processing modules and one singlechip integration control module form a collecting card; a plurality of the collecting cards are inserted and connected on a shared address, data, clock and triggering bus; one end of the data communication module is also inserted and connected on the shared address, data, clock and triggering bus while the other end thereof is connected with the collecting computer by a USB communication wire; the collecting system can completely meet vibration signal collecting requirement and simultaneously has multiple sampling channels and the function of collecting synchronous signals; the collecting system also has program control function, can meet the need of different sensor types, has high collecting speed, small volume and two collecting functions of common real-time collection and transient collection, can not only be applied to low-frequency vibration test, but also suitable for high-frequency vibration tests such as crash, explosion and the like.

The invention discloses a measuring device and method for the vibration of a flexible cantilever on the basis of machine vision. The measuring device comprises a fixed bracket, the flexible cantilever, a camera bracket, a CCD (Charge Coupled Device) camera, a lens, a plurality of LED (Light-Emitting Diode) light-emitting tubes and a PC (Personal Computer), wherein one end of the flexible cantilever is fixed on the fixed bracket; all the LED light-emitting tubes are arranged on the upper surface of the flexible cantilever in sequence; the top of the fixed bracket is provided with the camera bracket; the CCD camera is fixed on the camera bracket and is provided with the lens; and an output port of the CCD camera is connected with the PC. The CCD camera measures each frame image of the vibration of the LED light-emitting tubes, and conveys the images to the PC; and the PC processes a detected image sequence, extracts the position of the mass center of the light spots of the LED light-emitting tubes and acquires the vibration displacement of all the LED light-emitting tubes and parameters for reflecting the low-frequency vibration of the flexible cantilever structure. The measuring device and method disclosed by the invention has the advantages that the non-contact effect is achieved, the measuring range is wide and the vibration characteristic of a measured object is not changed and the like, and can be widely applied.

The invention provides a three-degree-of-freedom ultralow frequency vibration absorber which has a compact structure and belongs to the field of accurate vibration attenuation. The vibration absorber respectively utilizes the principle that the positive and negative rigidities are connected in parallel in three degrees of freedom to realize ultralow frequency vibration attenuation, greatly reduces the rigidity of the system on the premise of ensuring the bearing capacity of the system, and realizes the ultralow inherent frequency. The three-degree-of-freedom ultralow frequency vibration absorber adopts the manner that the magnetic positive rigidity and the magnetic negative rigidity are connected in parallel in the z direction and the manner that a flat spring and the magnetic negative rigidity are connected in parallel in the x direction and y direction, so that the integral structure is more compact, the ultralow inherent frequency is provided, excellent vibration attenuation effect is provided for medium-high frequency vibration interference, the low frequency vibration and the ultralow frequency vibration are effectively restrained, and the three-degree-of-freedom ultralow frequency vibration absorber is applicable to the accurate processing equipment and measuring equipment sensitive to vibrations.

The invention discloses a bistable piezoelectric cantilever beam vibrator device, which consists of a pedestal, piezoelectric ceramic, an elastic substrate, an electrode, a mass block and a pair of permanent magnets, wherein the piezoelectric ceramic is adhered to the elastic substrate; the electrode is plated on the piezoelectric ceramic; the mass block and a first permanent magnet are fixed at the free end of the elastic substrate; a second permanent magnet is arranged at a position, corresponding to the first permanent magnet, on the pedestal; and the first and second permanent magnets arearranged in a way that the same polarities are opposite. In the device provided by the invention, a piezoelectric cantilever beam vibrator can form a nonlinear bistable system by utilizing a nonlinear repulsive force between the permanent magnets, and can produce stochastic resonance phenomena under certain conditions to remarkably improve piezoelectric vibration generation efficiency in a broadband low-frequency vibration environment; and the device is particularly suitable for highly-efficiently capturing broadband, low-frequency and low-amplitude vibration energy.

Electromagnetic motor with a slider that moves linearly with respect to the stator in either direction. Embodiments include slider internal or external the stator. Slider includes one magnetic flux producing element in all embodiments. Internal slider embodiments stator includes a minimum of three magnetic flux producing elements and a maximum of four such elements. External slider embodiments stator includes two magnetic flux producing elements. All embodiments provide positive slider return to center at rest position. In internal slider embodiments the slider is centered within the stator resulting from either: a combination of a repelling force from a single magnetic flux producing element in opposition to gravitational pull on the slider due to its weight; or equal and opposite repelling forces on opposite sides of the stator from a magnetic flux producing element on opposite sides of the stator all three elements in longitudinal alignment with each other.

An apparatus for use in low frequency vibration energy harvesting (VEH) and with actuators requiring a low deflection force. The apparatus includes a piezo flexure that is loaded with a compressive pre-load force to place the piezo flexure under compression. The piezo flexure may be supported at an intermediate point or at one end thereof. The compressive pre-load force produces flexes the piezo flexure into one or the other of two stable positions, these positions being offset on opposite sides of a longitudinal centerline representing the position of the piezo flexure that would be produced without the compressive pre-load force applied thereto. The compressive pre-load effectively provides a negative spring constant which “softens” the piezo flexure and enhances a responsiveness of the piezo flexure to low frequency vibration energy. The piezo flexure also operates over a much wider frequency bandwidth than conventional systems incorporating a tip mass.

The invention provides an electrostatic microscope and a measurement method. The electrostatic microscope consists of a scan head, a low frequency voltage signal generator, a high frequency voltage signal generator, a low frequency vibration signal detector, a high frequency vibration signal detector and a controller; and the scan head comprises a probe, a probe location inductor, a piezoelectric vibration exciter and a piezoelectric scanner. Based on an existing electrostatic force microscope, a higher order eigenvibration mode of the probe is adopted to measure electrostatic force. As interaction of the probe and the sample is different in different vibration modes, the corresponding performance is different in aspects such as resolution, sensitivity, stability and the like. The electrostatic microscope can help significantly improve spatial resolution of the electrostatic force microscope in atmospheric environment.

The present invention relates to a skin management system, and in particular to a total skin management system and a total skin management method using the same which are capable of checking a state of skin and comprehensively managing a skin based on a type of skin. In addition, the present invention relates to a total skin management system and a total skin management method using the same which are capable of checking a state of skin and classifying the skin into numerous types by integrating and controlling the functions of a skin check, far infrared ray massage, ozone massage, low frequency massage, low frequency vibration massage and ultrasonic wave massage and comprehensively managing the functions of a skin cleansing, skin management, skin nutrition and skin elastic force increase through a certain skin exercise corresponding to a structure of skin based on a skin cell activity and metabolism in a proper combination with the functions of an infrared ray massage, ozone massage, low frequency wave massage, low frequency vibration massage and ultrasonic wave massage based on the checked type of skin.

The invention relates to an MEMS wideband piezoelectricity energy collector based on a bistable state frequency raising structure in the technical field of electric appliances, which comprises a frame, a bistable state beam arranged in the frame, a piezoelectric over hanging beam, a permanent magnet and a soft magnet. The MEMS wideband piezoelectricity energy collector is characterized in that twoends of the bistable state beam are both fixed on the frame, the permanent magnet is attached to the bistable state beam, on end of the piezoelectric over hanging beam is fixed on the frame, and thesoft magnet is arranged on the piezoelectric over hanging beam. The invention adopts a bistable state frequency raising structure to enable a piezoelectric transduction component to obtain greater output power in a low-frequency vibration environment. Compared with the prior MEMS piezoelectric energy collector, the invention has simple structure, easy manufacture and volume reduction, can be operated in a low-frequency environment, and can output stable frequency within wider environment vibration frequency range.

The invention discloses a low-frequency vibration-isolation combined sandwiched structure. The low-frequency vibration-isolation combined sandwiched structure comprises a lower uniform layer, a middle layer and an upper uniform layer sequentially from bottom to top, wherein the middle layer is of a limited two-dimension photonic crystal structure, the limited two-dimension photonic crystal structure comprises a base body and a plurality of scatters embedded into the base body, the scatters are respectively connected with the upper uniform layer and the lower uniform layer into a whole, and the lower uniform layer, the scatters and the upper uniform layer (3) are all made of rubber materials. The scatters, the upper layer and the lower layer are combined into an integrated body and are made of the same materials. The base body needs to be fixed. The low-frequency vibration-isolation combined sandwiched structure can block incident vibration along a plate and low-frequency vibration perpendicular to the plate through the designed structure, be applied to vibration control within the frequency range of hundreds of hertz, and serve as a low-frequency vibration-isolation facility of projects such as foundations and inner walls of buildings, ships and warships, and high-speed rails.

The present invention relates to a vibration signal processing method and system that can be used to account for situations where impact or impulse events are hidden in a normal vibration reading by low frequency vibrations and high frequency noise. In one preferred form, the method of the present invention comprises the steps of obtaining electrical vibration signals that represent mechanical vibrations of a machine (102-106), converting the electrical vibration signals into digital vibration samples (108), dividing the digital vibration samples into equal time intervals and determining the average absolute amplitude of the digital vibration samples for each time interval (110), generating a time waveform comprising the determined average amplitudes (112, 114), and processing the time waveform as if it were an independently-detected signal (116-120).