Abstract: A radio direction finder based on the simulated Doppler frequency shift principle is disclosed that is applicable to FSK encoded pulsed transmissions. Typical applications include tracking of stolen vehicles or shipped package tracking. During FSK decoding, all antenna elements of the antenna array are turned on in a non-rotating mode thus eliminating error due to the simulated antenna rotation modulation while providing enhanced gain for the FSK decoder circuit. After decoding a suitable FSK signal, a virtual antenna rotation is enabled, and the bearing is measured during the time interval when the transmitter is only broadcasting a carrier wave.

Abstract: A compound diaphragm bellows is provided that substantially increases the stroke of conventional viscous fluid dampers without significantly compromising radial stiffness. A method of restraining movement in a first plane while enhancing elastic movement in a plan perpendicular to the first plane is also provided. The disclosed compound diaphragm bellows are constructed by connecting alternating edges of flexible member pairs to rigid sleeves. Stiffening members may be added to enhance the compound diaphragm bellows' radial stiffness.

Abstract: A vibration isolation apparatus having a shaft with an axis therethrough. The shaft has a first and second end. A piston having an axial bore is coaxially positioned with the shaft to provide a damper by forming a damping path between the piston and the shaft. A flange extends radially from the piston for coupling the apparatus to a load. A first extension is coupled to and extends radially from the first end of the shaft and a second extension is coupled to and extends radially from the second end of the shaft. Secondary bellows extending from and secondary fluid paths extending through the first and second extensions provide a first volumetric stiffness in series with the damper. Primary bellows connect the flange to the first and second extensions and are coaxial with the shaft to provide a second volumetric stiffness parallel with the damper and the first volumetric stiffness.

Abstract: A system for isolating a supported structure from transmitting vibrations to a supporting base in a spacecraft provides six degrees of freedom in a kinematic mounting. Six isolator elements in a symmetric arrangement of three skewed isolator pairs provides viscous damping and vibration and shock attenuation during launch and operation in space. The isolators employ two degrees of freedom flexure joints at each mounting point to assure primarily axial deflection and minimize bending moments, and have tuning springs to optimize performance. The system permits deterministic design and allows calculation of all loads from the nominal geometry and the isolator axial stiffness. Limit stops are provided between the supporting structure and the supported structure to limit excursions of the isolator members.

Abstract: In a system for controlling or monitoring an object, wherein a position of the object must be determined, the system includes a first and second multispeed sensor, the first sensor having a speed of N and the second sensor having a speed of N-1. A method for determining the position of the object comprises the steps of obtaining position data as measured by the first and second multispeed sensor, respectively. A parameter, N.sub.A, a weighted difference between the obtained position data, is determined to ascertain whether a first or second case exists. If the first case exists, a first set of constants based on a first set of equations is generated; otherwise the first set of constants is generated based on a second set of equations. A second set of constants is then generated. Finally, the position of the object is determined by calculating the weighted average of the second constants, thereby obtaining the position of the object, utilizing the data provided by both sensors.

Abstract: The apparatus controls the positioning of a device in response to a commanded input signal, and comprises an element for moving the device in response to an error signal. A sensor component determines the actual position of the device, the sensor component outputting a primary signal and a derivative signal corresponding to the actual position and velocity of the device, respectively. A complementary filter system filters the primary signal and the derivative signal to generate a derived position signal, the derived position signal being combined with the commanded input signal thereby generating the error signal. The filtering results in effectively increasing the resolution of the sensor component thereby reducing the limit cycle caused by quantization of the sensor component.

Abstract: An apparatus for generating phase modulated angular positional signals in digital form. A phase tracking loop receives a phase modulated signal from the rotor of a resolver whose stator windings are excited in quadrature. The phase output of the resolver is proportional to the angular displacement of the rotor. Signals for exciting the stator windings of the resolver are applied in phase quadrature to a phase detector to develop an analog error signal when combined with the rotor output signal. The analog phase error signal provides an output indicative of the angular displacement of the rotor. The error signal is applied to a voltage controlled oscillator, converted to digital form, and combined with the excitation signals in a closed loop to force the error signal to a null, whereupon the indicated digital output angle is in coincidence with the angular displacement of the rotor shaft.

Abstract: A dual mode vibration isolator for reducing transmission of vibrations between a forward body and an aft body includes a mounting member positioned between the forward and aft bodies, a plurality of magnetic actuators each having an armature fixed to the forward body and a stator mounted on the mounting member, and a plurality of linear actuators pivotally connected between the aft body and the mounting member. The magnetic actuators support the forward body relative to the mounting member by magnetically supporting the armatures between paired stator cores in each stator. The magnetic actuators are controlled, preferably through local flux feedback loops, to permit the stators to vibrate relative to the armature without transmitting forces to the armatures, thus isolating the vibration of the aft body and mounting member from the forward body. The linear actuators extend and contract to reposition the forward body and mounting member relative to the aft body.

Abstract: A radio direction finding system based on the doppler frequency shift principle is disclosed which utilizes a polygonal shaped antenna array and a conventional FM receiver. Voltages from each antenna are combined in an rf summing circuit which may be located remotely from the antenna. Audio output from the FM receiver is processed to measure the phase angle of the commutation frequency phase modulation imparted to the rf receiver input signal by gain variations within the rf summer circuit. Bearing angle proportional to the measured phase angle is displayed in a circular array of light emitting diodes and a three digit decimal display and is provided for recording or remote display through a serial interface.