Hughes Aircraft Company

Raytheon Company

Hughes Aircraft

Eric K Slater

Kirk K Kohnen

Paul L Feintuch

Wilbur W Eaton

James William Casalegno

Frank Philip Monte

James W Casalegno

An analog-to-digital converter system for sampling an input signal includes at least one offset channel. Each channel includes a differential amplifier with a signal input coupled to the input signal, an offset input for receiving an offset signal and an amplified difference output, an analog-to-digital converter having a signal input coupled to the amplified difference output and having a signal output, and an offset index signal source coupled to the differential amplifier offset input. The system further includes an offset controller having at least one output coupled to a corresponding at least one offset index signal source and at least one input coupled to a corresponding at least one analog-to-digital converter signal output. The system also includes a signal constructor having at least one input coupled to a corresponding at least one analog-to-digital converter signal output and operable to provide a relatively high resolution digital output signal.

High resolution, high dynamic range analog-to-digital converter system and related techniques

An improved digital fluxgate magnetometer that uses digital logic and a high resolution digital to analog converter to digitize a magnetic signal for use by signal processing algorithms. The magnetometer includes an oscillator that outputs an oscillator signal and a magnetic fluxgate sensor having a drive coil coupled to the oscillator, a feedback coil, and a sense coil. An analog multiplier is coupled to the sense coil and the oscillator and outputs a signal to an analog low pass filter. A comparator is coupled to the analog multiplier, and a register is coupled to the comparator and outputs a logical 1 or a logical 0 in accordance with the output of the comparator. A digital filter receives the output of the register and produces a digital output of the digital fluxgate magnetometer. A high resolution digital to analog converter is coupled between the register and the feedback coil of the magnetic fluxgate sensor in a feedback loop of the sensor. The digital to analog converter produces a very high resolution digitized output (typically &gt;22 bits) that is necessary to adequately represent the dynamic range of the sensor.

High dynamic range digital fluxgate magnetometer

Self leveling apparatus that includes a frame, a device that is to be leveled, and a leveling mechanism such as a double ring gimbal having an inner gimbal ring and an outer gimbal ring. The outer gimbal ring is secured to the frame and the inner gimbal ring is secured to the device and to the outer ring. The inner ring comprises a viscous or preloaded bearing that allows the device to swing around an inner ring axle to thereby level itself in that axis and prevent spurious movement of the device. The outer gimbal ring and inner gimbal ring are attached by outer axles that comprise a viscous or preloaded bearing that allow the inner gimbal ring to swing around the outer axles thereby level the inner gimbal ring in that axis and prevent spurious movement of the device. A disclosed embodiment of the invention includes a magnetometer sensor that is coupled to signal processing and telemetry electronics and a power source that are leveled to keep axes of the sensor oriented along horizontal and vertical axes.

Self leveling sensor/device package

Digital logic and a high resolution digital to analog converter are used to adequately digitize a magnetic signal that is subsequently processed by magnetic data processing algorithms. The high resolution digital to analog converter is directly incorporated in a feedback loop of a magnetometer sensor, an expensive precision analog to digital converter is replaced by a less expensive, lower power digital to analog converter. The circuit improvement provided by the present invention includes an analog low pass filter coupled to the sensor, a digital logic circuit coupled to the analog low pass filter for providing an output signal from the magnetometer and a feedback output signal, and the digital to analog converter coupled between the digital logic circuit and a feedback coil of the sensor for coupling the feedback output signal thereto. The digital logic circuit includes an analog to digital converter, an adder having a first input coupled to the analog to digital converter, and an accumulator coupled between an output of the adder and a second input of the adder. The digital logic circuitry processes the error signal from the analog multiplier, eliminates high frequency components, and digitizes the result. Thus, a low resolution analog to digital converter, having a resolution of only a few bits, may be used.

Digital flux gate magnetometer

Digital logic comprising a high speed analog to digital converter, a high speed analog to digital converter, a digital multiplier, and an infinite impulse response filter and decimation circuit are used to digitize a magnetic signal that is subsequently processed by magnetic data processing algorithms. The high resolution digital to analog converter is directly incorporated in a feedback loop of a magnetometer sensor, and an expensive precision analog to digital converter is replaced by a less expensive, lower power digital to analog converter. The improvement provided by the present invention includes a high speed analog to digital converter coupled between the oscillator and a first input of a multiplier, and a second analog to digital converter that is coupled between the sense coil of the sensor and a second input of the multiplier. The output of the multiplier is coupled to an infinite impulse response filter and decimation circuit that produces the digital output signal from the magnetometer. The output of the infinite impulse response filter and decimation circuit is coupled by way of a digital to analog converter to the feedback coil of the sensor. Depending on the system requirements, the two analog to digital converters, the digital multiplier, and the infinite impulse response filter and decimation circuit may be implemented in one readily available microcontroller at low cost. This serves to reduce the number of components, complexity, and expense of the magnetometer.

Advanced digital flux gate magnetometer

An improved method and apparatus for controlling the display of a plan position indicator radar display are disclosed which result in the elimination of both display flicker and the loss of critical real-time radar return data. The system is clocked by a series of fixed pulses related to the length of the radar beam on the display. Creation of the radar beam is given top system priority. Thereafter, the number of clock pulses allocated for radar beam creation is diminished as necessary to provide time for the display of prestored synthetic display data. The time is taken from a portion of each beam which has been preselected as least critical. Additionally, the beam length based clock pulses are employed to compensate for sweep overlap and in such functions as offset, range scale, and sweep off-scale.

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Long Beach, CA, United States of America

Eric K Slater