Abstract: A method of providing position estimation with a navigation device comprises periodically recording magnetic field strength of an area substantially surrounding a navigation device as a user of the navigation device traverses a select pathway. The method combines the recorded magnetic field strength with measurements from at least a dead reckoning portion of the navigation device to provide position estimates along the select pathway. The method further corrects each of the position estimates from a starting position on the select pathway, where each of the corrected position estimates have an error value below one or more previous position estimates and any intervening positions between each of the one or more previous position estimates and the starting position, with the error value corresponding to an error threshold based on the previous position estimates.

Abstract: A method of providing position estimation with a navigation device comprises periodically recording magnetic field strength of an area substantially surrounding a navigation device as a user of the navigation device traverses a select pathway. The method combines the recorded magnetic field strength with measurements from at least a dead reckoning portion of the navigation device to provide position estimates along the select pathway. The method further corrects each of the position estimates from a starting position on the select pathway, where each of the corrected position estimates have an error value below one or more previous position estimates and any intervening positions between each of the one or more previous position estimates and the starting position, with the error value corresponding to an error threshold based on the previous position estimates.

Abstract: Systems and methods for determining a directional movement of an object such as a wheeled vehicle. The system includes a magnet having a north pole and a south pole mounted to the object, a single magnetic sensor positioned such that the sensor can individually detect each magnetic pole as the object moves, the sensor configured to produce a first characteristic signal when a north pole is detected and a second characteristic signal when a south pole is detected, and a processing device in signal communication with the sensor, the processing device configured to determine a directional movement of the object based on a configuration of a signal doublet that includes the first and second characteristic signals. The methods include sensing the north and south poles as they pass the magnetic sensor and determining a direction based on an order in which the north and south poles are sensed.

Abstract: A method of providing position estimation with a navigation device comprises periodically recording magnetic field strength of an area substantially surrounding a navigation device as a user of the navigation device traverses a select pathway. The method combines the recorded magnetic field strength with measurements from at least a dead reckoning portion of the navigation device to provide position estimates along the select pathway. The method further corrects each of the position estimates from a starting position on the select pathway, where each of the corrected position estimates have an error value below one or more previous position estimates and any intervening positions between each of the one or more previous position estimates and the starting position, with the error value corresponding to an error threshold based on the previous position estimates.

Abstract: Systems and methods for determining a directional movement of an object such as a wheeled vehicle. The system includes a magnet having a north pole and a south pole mounted to the object, a single magnetic sensor positioned such that the sensor can individually detect each magnetic pole as the object moves, the sensor configured to produce a first characteristic signal when a north pole is detected and a second characteristic signal when a south pole is detected, and a processing device in signal communication with the sensor, the processing device configured to determine a directional movement of the object based on a configuration of a signal doublet that includes the first and second characteristic signals. The methods include sensing the north and south poles as they pass the magnetic sensor and determining a direction based on an order in which the north and south poles are sensed.

Abstract: A method of providing position estimation with a navigation device comprises periodically recording magnetic field strength of an area substantially surrounding a navigation device as a user of the navigation device traverses a select pathway. The method combines the recorded magnetic field strength with measurements from at least a dead reckoning portion of the navigation device to provide position estimates along the select pathway. The method further corrects each of the position estimates from a starting position on the select pathway, where each of the corrected position estimates have an error value below one or more previous position estimates and any intervening positions between each of the one or more previous position estimates and the starting position, with the error value corresponding to an error threshold based on the previous position estimates.

Abstract: Data is sent over a digital communication network in a message frame which includes a header, a data field and an end delimiter. An analyzer for such a network evaluates the response of network interface devices to test message frames. Included in the analyzer is a mechanism for creating a test message frame which allows the user to define a number of pad-idle symbols, a sequence of symbols for a start delimiter, a series of symbols for the data field and a set of symbols for the end delimiter. The use defined test message frame may include invalid symbols to test the error response of the interface device. A transmitter is provided for repeatedly sending the test message frame to the network interface device with a given number of silence symbols inserted between each repetition. The analyzer has a section for receiving message frames back from the network interface device and sequentially comparing the symbols of the test message frame to those of the received message frame.

Abstract: A method for positioning and maintaining a disc head over a desired track centerline on a disc rotatably carried on a disc drive. The distance between the current position of the disc head and the desired track centerline is monitored, and a signal generally proportional to that distance is applied to the disc head moving mechanism to cause the disc head to move toward the track centerline. The control signal is clipped if it exceeds predetermined maximum and minimum values.