Abstract: A notch filter circuit is provided including a first stage circuit and a second stage circuit. The first stage circuit sums a filter input signal with a filter output signal to form a summation signal. The second stage circuit includes a first tee network and a second tee network. The first tee network low-pass filters the filter input signal to form a first tee output signal. The second tee network high-pass filters the summation signal to form a second tee output signal. A first multiplying digital-to-analog converter is electrically coupled to the first tee network and the second tee network. The first converter modifies the gain of the second tee network in response to a gain signal to form a corrected second tee network signal, thereby adjusting a notch filter frequency.

Abstract: A notch filter circuit is provided including a first stage circuit and a second stage circuit. The first stage circuit sums a filter input signal with a filter output signal to form a summation signal. The second stage circuit includes a first tee network and a second tee network. The first tee network low-pass filters the filter input signal to form a first tee output signal. The second tee network high-pass filters the summation signal to form a second tee output signal. A first multiplying digital-to-analog converter is electrically coupled to the first tee network and the second tee network. The first converter modifies the gain of the second tee network in response to a gain signal to form a corrected second tee network signal, thereby adjusting a notch filter frequency.

Abstract: A micro-gyroscope (10) having closed loop operation by a control voltage (VTY), that is demodulated by an output signal of the sense electrodes (S1, S2), providing Coriolis torque rebalance to prevent displacement of the micro-gyroscope (10) on the output axis (y-axis). The present invention provides wide-band, closed-loop operation for a micro-gyroscope (10) and allows the drive frequency to be closely tuned to a high Q sense axis resonance. A differential sense signal (S1−S2) is compensated and fed back by differentially changing the voltage on the drive electrodes to rebalance Coriolis torque. The feedback signal is demodulated in phase with the drive axis signal (K&ohgr;⊖x) to produce a measure of the Coriolis force.

Abstract: Planar vibratory gyroscope structures are provided which are inherently symmetric, which facilitate the use of simple monolithic fabrication processes and which enable the use of sensitive control and sense systems. A planar vibratory member of these structures has a hollow frame, a plate that has a plate perimeter and is positioned within the frame and a plurality of elongate beams which couple the plate to the frame wherein each of the beams is proximate to and substantially parallel to a respective portion of the plate perimeter. The exterior rim of the planar member can be supported by a substrate which provides room for easy access to the plate with mode control and sense systems.

Abstract: A balanced vibratory micro-gyroscope having an electrode pattern having four inner drive electrodes and four outer sense electrodes for providing balanced push-pull control of a cloverleaf micro-gyroscope. A control circuit utilizes equal and opposite input signals to the drive electrodes and processes output signals from the sense electrodes to precisely control the drive electrodes. Capacitance is added between opposing drive and sense electrodes pattern in order to null capacitive coupling effects between adjacent drive and sense electrodes. The control circuit linearizes the force on the micro-gyroscope thereby improving performance. Advantage is taken of Coulomb's Law to eliminate an electronic multiplier in the vibration amplitude control loop. A simplified full-wave rectifier further enhances the control circuit and operation of the micro-gyroscope.

Abstract: A motor current sensing circuit using a single sensing resistor in the motor current path to sense the current from the voltage source. The circuit includes an amplifier and a unity-gain inverter that translate the current across the sensing resistor into a voltage analog of the current in the motor. At any instant in time, the magnitude of the voltage across the sensing resistor is proportional to the magnitude of the motor current. During the forward portion of the duty cycle, a high-speed switch connects the sensor output to the amplified sensed bus current analog. During the reverse portion, the sensor output is connected to the inverted bus current analog. The average value of the sensor output is the voltage analog of the average value of the motor current.

Abstract: A cantilevered micro-beam formed on a micro-circuit substrate such that when beam is vibrated it produces an output signal directly related to rotation of the substrate about an axis perpendicular to the beam and the direction of vibration.

Abstract: A high-accuracy, low-cost rotation rate sensor is based on a vibrating mechanical element induced to laterally oscillate. When rotated, the element, preferably a cantilever beam, is subjected to a Coriolis force that is proportional to the rate of rotation. The Coriolis force, if not counteracted, would cause the beam to move vertically. Vertical motion is detected with a highly sensitive tunneling tip sensor positioned below the beam. A wide bandwidth control circuit applies a counteracting force to the beam to keep the gap between tip and beam constant. This counteracting force varies with and provides an indication of the rotation rate. Lateral oscillation is induced by applying an electrostatic force to the beam with narrow, bipolar pulses that improve the sensor's stability and accuracy.

Abstract: A transformer driver having an unlimited duty cycle capability is disclosed herein. The transformer driver 10 of the present invention is coupled to an output circuit 20 and includes a transformer 32 having primary winding and secondary windings 30 and 34. The inventive driver 10 further includes a generator 26 for applying a plurality of charging pulses P1, P2 to the primary transformer winding 30 to keep the transformer from being saturated. A transistor buffer network 36 selectively electrically isolates the output circuit 20 from the transformer. In a particular embodiment the charging pulses P1, P2 serve to maintain the voltage at the control terminal 38 of a power transistor included within the output circuit.

Abstract: A power loss protection system for use in a system having a spinning momentum wheel and connected to a power bus. The inventive system (10) isolates a protected circuit from the power bus (11) in the event of a system power loss and converts and regulates power taken from the kinetic energy stored in the spinning momentum wheel to a voltage sufficient to maintain operation of the protected circuit. In a most general sense, the inventive system includes a power loss detector (21) for detecting a power loss in the system bus and providing a first signal in response thereto and a regulator (26) for regulating the voltage derived from the momentum wheel energy to the protected circuit in response to the first signal.

Abstract: A phase compensation circuit for use with a resolver circuit that compensates for resolver angle measurement error without the use of special compensation windings on the resolver or the buffer amplifier associated with the compensation windings. With the present invention, primary windings from a plurality of resolvers may be reduction over conventional circuits. A digital computer is employed to process integrated data indicative of the phase shift of signals generated by the resolver, and compute error correction signals that compensate sine and cosine angle data output signals of the resolver. No resolver compensation windings are necessary and no additional electronic equipment is necessary. The present invention provides increased accuracy to fulfill more stringent angle measurement specifications.

Abstract: An improved infrared sensor is provided which is of the type which scans across a spatial region and detects infrared energy radiating from a celestial body and in which an input electronic signal is produced in response to the detected infrared energy, wherein the improvement comprises: amplifier circuit means for providing an amplified output signal in response to the input electronic signal; threshold detection circuit means for detecting when the output electronic signal reaches a prescribed threshold level substantially below a saturation level of said amplifier circuit means said threshold detection circuit means comprising a thresholding circuit for providing a turn-on signal when the output signal reaches the prescribed threshold level; and feedback circuit means for providing a feedback signal for limiting the input electronic signal provided to said amplifier circuit means, said feedback circuit means comprising a feedback amplifier circuit responsive to the turn-on signal, such that the feedback si

Abstract: An electronic logic circuit utilized in conjunction with a scanning infrared detector to generate pulses which accurately indicate the precise location of the center of a preselected astronomical radiant body, such as the earth, notwithstanding a wide scanning frequency range with unknown initial value, and capable of rejecting undesirable input signals, is disclosed. The pulses are initially generated so as to conform the frequency of a generated signal to that of the signal applied from the infrared detector, thereby correcting the large initial signal frequency error. Both the conditions of an initially high and low frequency of oscillation of the generated signal relative to the applied signal are corrected. After such frequency correction has been rendered, signal phase correction is accomplished so as to negate the difference between the exact center of the signal applied from the infrared sensor and the trailing edge of the generated signal.

Abstract: An adaptive comparator is provided which compares a signal from a horizon sensor of a satellite to a predetermined threshold to provide a signal indicative of the relative position of a celestial body with improved noise immunity. When the comparator receives a signal from the horizon sensor which exceeds the threshold, an output is provided which may be used to change the orientation of the spacecraft. The comparator includes circuitry for ascertaining the average of one or more of the most recent input pulses which exceeded the previous threshold. This average is then utilized to set a new or adapted threshold. The subsequent input signal is then compared to the adapted threshold and the recursive process continues.