Abstract: A method for determining a resonant frequency of a mechanical device having a first mass and at least one second mass mechanically coupled to the first mass comprises the steps of: providing a control signal to a voltage-controlled oscillator (VCO) to control the frequency of an output thereof; translating a phase shifted output of the VCO into an oscillatory force which is applied to one of the first and second masses to cause the mechanical device to respond; measuring the response of the mechanical device and generating a response signal representative thereof in frequency and amplitude; generating an error signal proportional to the phase difference between a signal representative of the output of the VCO and the measured response signal; adjusting the control signal to cause the oscillatory force applied to the one mass to sweep within a calculated frequency range rendering the amplitude of the response signal to approach and exceed a calculated threshold value; and when the calculated threshold is excee

Abstract: A method and apparatus for measuring the frequency of a desired resonant mode of a crystal arrangement, or other two-port device, during an automated operation. The crystal arrangement, or other two-port device, is placed into a test circuit and subjected to a sinusoidal test signal of known frequency. Based upon the output response of the crystal arrangement to the test signal, the frequency of the test signal is changed such that the test signal rapidly converges on a desired mode of operation of the crystal arrangement. This is accomplished by first noting a desired increase in amplitude of the output response of the crystal arrangement, followed by measuring an error signal related to the desired crystal arrangement mode of operation. When the error equals a predetermined value the frequency of the sinusoidal test signal is the frequency of the desired mode.

Abstract: A method and apparatus for measuring the frequency of a desired resonant mode of a crystal arrangement, or other two-port device, during an automated operation. The crystal arrangement, or other two-port device, is placed into a test circuit and subjected to a sinusoidal test signal of known frequency. Based upon the output response of the crystal arrangement to the test signal, the frequency of the test signal is changed such that the test signal rapidly converges on a desired mode of operation of the crystal arrangement. This is accomplished by first noting a desired increase in amplitude of the output response of the crystal arrangement, followed by measuring an error signal related to the desired crystal arrangement mode of operation. When the error equals a predetermined value the frequency of the sinusoidal test signal is the frequency of the desired mode.

Abstract: A hand-held instrument (10) and associated method for providing optical measurements of the contour, range and motion of an object, such as a tympanic membrane of an ear, in real time, and to provide for simultaneous visualization of the object. The instrument (10) includes an illumination source (22) that projects an optical beam (24) through a grating (26) onto a gradient of refractive index lens (32) to project light and dark fringes onto the object at stepped phases determined by the grating position. Light reflected from the object is collected and focused onto an eye piece (18) to be observed by the operator. Simultaneously, reflected light from the object is focused onto a camera (46). The camera (46) generates an electrical signal in proportion to the light intensity received by the camera (46) to generate an image of the object. The image is then transmitted to processing systems to compute phase relationships in the reflected grating image to generate a contour map of the object.

Abstract: Detection and gauging of a joint (18) in a rotating and axially moving drilling tool (16) subject to transverse axial displacement is achieved by positioning an ultrasonic sensor assembly (12) coaxially encircling the tool in a plane perpendicular to the tool. The sensor assembly (12) generates more than one reflected pulse to represent changes in tool (16) diameter by transmitting a beam from at least one ultrasonic sensor (32) toward the tool (16) as the tool axially advances or recedes, perpendicularly piercing the plane of the sensor assembly (12). Each reflected pulse is converted to an electrical output signal, all of which signals are summed to minimize measurement distortion due to noise and transverse axial displacement of the rotating tool and compared to a threshold detection voltage in a signal processor (14) to generate a detection output pulse.