Abstract: The compass system of the present invention utilizes an improved calibration routine in which a processing circuit of the compass recalibrates the compass each time three data points are obtained from a magnetic field sensor that meet predetermined criteria. One such criterion is that the three data points define corners of a triangle that is substantially non-obtuse. When three data points have been obtained that define a triangle meeting this criterion, the processing circuit calculates a center point for a circle upon which all three data points lie by solving the equation x2+y2+Ax+By+C=0 for A, B, and C, using the coordinate values (x,y) for the three data points and defining the center point as (−A/2, −B/2).

Abstract: An electronic compass system of the present invention includes a sensor for detecting the earth's magnetic field and for providing electrical signals representing the direction of the vehicle, a heading indicator for indicating vehicle headings in response to received vehicle heading signals, and a processor coupled to the sensor for receiving the electrical signals and coupled to the heading indicator for supplying the vehicle heading signals to the heading indicator.

Abstract: A dual-axes position sensor 10 having an outer housing 12, an actuator 40, a linear Hall effect sensor assembly 20 for detecting position changes along a first (y) axis, and a linear Hall effect sensor assembly 30 for detecting position changes along a second (x) axis is disclosed. The housing 12 is preferably made out of a non-magnetic material such as plastic. Actuator 40 is rod shaped and coupled to a movable device or shaft (not shown) that is to have its position sensed. The linear Hall effect sensor assembly 20 is unattachably positioned to set on lip 52 of the housing 12, and includes a magnetically conducting pole piece 26, a magnet assembly 24 comprising an upper magnet 21 and a lower magnet 23 that are separated by an air gap 25. Magnet assembly 24 and pole piece 26 are positioned around a Hall sensor device support 14 in a“U” shaped configuration or form. Hall sensor device support 14 is fixedly attached to housing 12 via attachment area 54.

Abstract: A dual positional hall effect sensor 10 having an outer housing 12, an actuator 14, a linear movement sensor 20, and a rotational movement sensor device 22. The housing 12 includes a lower chamber 24 and an upper chamber 26, with a barrier wall 28 separating therebetween. The actuator 14 is made up of a coupling 32 for coupling to a movable device (not shown) that is to have its position sensed, a rod 34 that extends from the lower to the upper chamber, a collar 36 for retaining the actuator 14 within the lower chamber, and a key 38. The linear motion sensor 20 is unattachably positioned to set on collar 36, and includes a magnetically conducting pole piece 42 and a left and right magnets 44. The magnets 44 and pole piece 42 are positioned around the rod 34 in a "U" shaped configuration. The lower chamber 24 also includes a positionally fixed hall effect sensor 46 and a spring 48 positioned between the barrier wall 28 and the collar 36.

Abstract: A vehicle compass system including a magnetic field sensor from which the earth's magnetic field can be detected in two channels of measurement. The sensor is coupled to a processing circuit which samples the sensor data and determines the maximum and minimum signal levels in each channel of measurement during movement of the vehicle through a 360.degree. path of travel. Based on the spans between the maximum and minimum signal levels, adjustment signals are generated for adjusting the resolution of the compass system and the maximum and minimum signal levels of subsequent sensor data so that the system's sensitivity resolution may be adjusted and accurate heading information can be calculated and displayed regardless of the strength of the earth's magnetic field.

Abstract: A vehicle compass system having a magnetic field sensor coupled to a processing circuit which samples the sensor data and implements a calibration routine that generates compensation signals to compensate the sensor for the effects of vehicular magnetism so that accurate heading information can be displayed on a display coupled to the processing circuit. If the signal levels detected are outside of a variable threshold, then the calibration routine is run. Also provided is a circuit for receiving vehicle position information in response to which the processing circuit adjusts the signals supplied to the display in order to account for magnetic variations between the true north and magnetic north.

Abstract: An electrical system providing automatic calibration of a vehicle compass for abrupt and significant changes in vehicle magnetism. The system includes a magnetic field sensor providing signal information representing the magnetic field sensed within the vehicle. Coupled to the sensor is an electrical circuit for processing the signal information from the sensor to determine if a shift in vehicle magnetism has occurred and for calculating compensation signal information to provide a corrected heading display.

Abstract: An electronic vehicle theft detection system employing a magnetic field sensor for mounting within a vehicle to provide signal information representing the earth's magnetic field. The sensor is coupled to an electrical processing circuit for sampling the data provided by the sensor and for generating a theft alarm signal when the heading of the vehicle has changed due to unauthorized movement of the vehicle.

Abstract: An electrical power extension cord having an illuminated connecting body at an end of the extension cord is described. The end is illuminated if it is connected to an active power source with or without a functioning ground conductor, depending upon the electrical configuration within the body. The body is formed from a translucent material having the illumination apparatus embedded within such that the illuminated body is visible from all directions.

Abstract: An instrument probe has two sensing elements; one is a self heated thermistor that serves as the air velocity sensor, and a second sensing element in the form of a chip thermistor, that are separately but simultaneously exposed, in the use of the instrument probe, to the air flow, with the self heated thermistor and the thermistor chip are incorporated in a self regulating bridge circuit, that, when the unit is powered, generates a non-linear signal that is applied to signal processing circuitry within the unit housing to adjust same for gain and off set with the resulting signal being applied to a linearizer circuit also within the unit housing wherein the signal is electronically processed to supply the unit output signal in the familiar 4-20 milliamp range. The transmitter device is arranged to be powered by either an alternating current or direct current supply that is in the range of about 22 volts to about 28 volts.