Abstract: A navigation system and method for gyrocompass alignment in a mobile object. The system includes an inertial measurement device configured to provide a first set of sensor data and a positioning unit configured to provide a second set of data. In an example embodiment, the navigation system includes a processing device configured to receive the data sets provided by the inertial measurement device and the positioning device, and the processing device is configured to dynamically calibrate the received first data set the processing device includes a Kalman filter, and the processing device is further configured to generate a gyrocompass alignment using the first dynamically calibrated first data set, the second data set, and the Kalman filter. The method includes receiving sensor data from a plurality of sensors, dynamically calibrating at least a portion of the sensor data, and generating gyrocompass alignment information based on the dynamically calibrated sensor data.

Abstract: Methods and systems for implementing an iterated extended Kalman filter within a navigation system are provided. In one embodiment, a Kalman filter programmed with time updating error states and measurement updating error states relating to received data sets is provided. The said Kalman filter configured to: iterate both the time updating error states and the measurement updating error states based on a first criteria; and iterate only the measurement updating error states based on a second criteria.

Abstract: Methods and systems for implementing an iterated extended Kalman filter within a navigation system are provided. In one embodiment, a Kalman filter programmed with time updating error states and measurement updating error states relating to received data sets is provided. The said Kalman filter configured to: iterate both the time updating error states and the measurement updating error states based on a first criteria; and iterate only the measurement updating error states based on a second criteria.

Abstract: A navigation system for a vehicle is described that includes an inertial measurement unit, a positioning unit, and a processing unit. The inertial measurement unit configured to provide a first set of data relating to operation of the vehicle and the positioning unit is configured to provide a second set of data relating to operation of the vehicle. The processing unit is configured to receive the data sets provided by the inertial measurement unit and the positioning unit and the processing unit comprises an error processing device. The error processing device is programmed with time updating error states and measurement updating error states relating to the data sets received by said processing unit and is configured to iterate both the time updating error states and the measurement updating error states based on a first criteria and iterate only the measurement updating error states based on a second criteria.

Abstract: A navigation system and method for gyrocompass alignment in a mobile object. The system includes an inertial measurement device configured to provide a first set of sensor data and a positioning unit configured to provide a second set of data. In an example embodiment, the navigation system includes a processing device configured to receive the data sets provided by the inertial measurement device and the positioning device, and the processing device is configured to dynamically calibrate the received first data set the processing device includes a Kalman filter, and the processing device is further configured to generate a gyrocompass alignment using the first dynamically calibrated first data set, the second data set, and the Kalman filter. The method includes receiving sensor data from a plurality of sensors, dynamically calibrating at least a portion of the sensor data, and generating gyrocompass alignment information based on the dynamically calibrated sensor data.

Abstract: An improved per-tone FEQ method with a noise reduction technique using periodic training pilot tones increases the throughput for long-reached modems. This method can reduce the noise effects in estimating FEQ equalizer coefficients. Each per-tone FEQ can be estimated by using the periodic training signals and an averaging technique to remove noise from each sub-channel (EQN. VI). After solving the system equations (EQN. IV), per-tone equalization coefficients of the FEQ equalizer for each group can be combined to obtain the optimized results in the form of the Toeplitz matrix (EQN. V). Each element within the Toeplitz matrix can be derived from the averaging technique used to remove noise from each sub-channel (EQN. VI). To demodulate a signal with the Toeplitz matrix, an inverse of every element in a row of the Toeplitz matrix is taken and multiplied by the sending signal which creates an N Log N matrix.

Abstract: A navigation system for a vehicle is described that includes an inertial measurement unit, a positioning unit, and a processing unit. The inertial measurement unit configured to provide a first set of data relating to operation of the vehicle and the positioning unit is configured to provide a second set of data relating to operation of the vehicle. The processing unit is configured to receive the data sets provided by the inertial measurement unit and the positioning unit and the processing unit comprises an error processing device. The error processing device is programmed with time updating error states and measurement updating error states relating to the data sets received by said processing unit and is configured to iterate both the time updating error states and the measurement updating error states based on a first criteria and iterate only the measurement updating error states based on a second criteria.

Abstract: The method and apparatus in accordance with the present invention provides signal-to-noise ratio improvement through noise reduction by means of spectral averaging and subcarrier based averaging techniques.

Abstract: A quadrature amplitude modulation implementation incorporating a symmetric spherical quadrature amplitude modulation constellation. The symmetric spherical quadrature amplitude constellation, as displayed in a multi-dimensional complex plane, is bounded by a surface comprising all symbol points at a predetermined distance from a center point and coincident with the intersection of at least two axes, and exhibiting correspondence in relative position of the symbol points on opposite sides of the at least two axes.

Abstract: The present invention discloses an improved initialization method for modem communication wherein the timing offset required for synchronization is estimated utilizing an entire received DMT frame and the channel impulse response is estimated utilizing the pilot tones received within the same DMT frames utilized for synchronization.

Abstract: An improved per-tone FEQ method with a noise reduction technique using periodic training pilot tones increases the throughput for long-reached modems. This method can reduce the noise effects in estimating FEQ equalizer coefficients. Each per-tone FEQ can be estimated by using the periodic training signals and an averaging technique to remove noise from each sub-channel (EQN. VI). After solving the system equations (EQN. IV), per-tone equalization coefficients of the FEQ equalizer for each group can be combined to obtain the optimized results in the form of the Toeplitz matrix (EQN. V). Each element within the Toeplitz matrix can be derived from the averaging technique used to remove noise from each sub-channel (EQN. VI). To demodulate a signal with the Toeplitz matrix, an inverse of every element in a row of the Toeplitz matrix is taken and multiplied by the sending signal which creates an N Log N matrix.