A short circuit current limiting reactor is disclosed having a series pass inductor wound on a core. A saturation control circuit is employed to control the magnetic saturation of the core. Under normal operating conditions, the core is in magnetic saturation thus making the reactance of the inductor negligible and allowing an AC current to flow freely through the inductor. Upon the occurrence of a short circuit fault, the saturation control circuit brings the core out of its magnetically satura...

A master clock generator for a variable speed constant frequency electric power system includes a frequency select circuit for selecting an external or internal frequency reference signal and a phase comparator for producing a phase error signal representative of the phase difference between the frequency reference signal and an output clock signal. The phase error signal is combined with a control signal to produce an adjusted phase error signal. This adjusted phase error signal is integrated a...

A circuit is provided for detecting phase error between two signals by producing a phase error signal having a series of pulses wherein the widths of the pulses are representative of the phase error and producing a polarity signal representative of the polarity of the phase error. The phase error signal and polarity signal are used to produce a count representing the magnitude and polarity of the phase error for each of the pulses in the phase error signal. This count is converted to an analog s...

A portable siting system particularly useful for siting a portable localizer for a collocated approach guidance system for aircraft utilizes a laser range finder in conjunction with a shaft encoder to determine the distance between the localizer and two arbitrary points along a runway center line as well as the azimuth offset between the two points. A microprocessor is used to compute the number of degrees the antenna of the localizer must be rotated so that its beam intersects the extended runw...

An integrated landing system interleaves signals encoded in a first format such as the microwave landing system that (MLS) format with signals encoded in a second format such as the precision tactical approach guidance (PTAG) format to permit approach guidance information to be transmitted to aircraft having either MLS receivers or PTAG receivers.

A push-pull accelerometer in which both force transducers lie in a common plane. Thus, when implemented in silicon micromachined device, both transducers can be fabricated from a single crystal layer, thereby producing transducers with closely matched common mode responses.

A fiber optic transducer utilizes a single optical fiber having one end surface, disposed adjacent a sensor element, cut at an angle to result in frustrated total internal reflection. The end surface of the optical fiber is spaced away from the sensor element. As the sensor element is displaced with respect to the end surface of the optical fiber, the amount of light reflected from the sensor element varies. Light injected into the optical fiber is reflected back toward the light source until th...

A drive system for providing different excitation voltages to the separate beams of a multiple beam vibrating transducer is disclosed. In one embodiment of the invention an amplified voltage at the resonant frequency of a master beam is amplified and applied to a secondary beam, to force the secondary beam to vibrate at the resonant frequency and amplitude of the master beam to force the transducer to resonate at the frequency of the master beam. Since the transducer vibrates at the resonant fre...

A thermal actuator utilizes a bimetallic snap action member such as a disc to actuate a member such as the armature of a switch to effect opening and closing of the switch. A resilient biasing member, such as an elongated curved spring member or a compressible member, engages the bimetallic member on a side opposite that of the actuated member to oppose the force exerted by the actuated member during the operation of the actuator.

A guidance system for landing an aircraft is described which uses a source of signals identifiable with the aircraft and a ground station which is linked to the aircraft. Specifically, the ground station includes a receiver which is connected to one or more pairs of antennas having a fixed, overlapping, directional sensitive pattern symmetically located relative to the center of the landing path, a receiver and a processor for measuring the relative sensitivity of the signals received at the ant...