Abstract: A receiver device to receive an incoming radio frequency (RF) satellite signal from a satellite vehicle includes a processor and computer-readable storage media. The computer-readable storage media is communicably connected to the processor and has instructions stored thereon that, when executed by the processor, causes the processor to track the incoming RF satellite signal in code phase and carrier frequency, the incoming RF satellite signal having a primary pseudorandom (PRN) code and a secondary PRN code modulated thereon, generate an encoded sequence of dot product values of adjacent integrated in-phase (I) and quadrature-phase (Q) components of the incoming RF satellite signal, compare the encoded sequence with expected secondary code chip transitions, determine a secondary code phase for the secondary PRN code based on the comparison, and coherently integrate the secondary code phase with the incoming RF satellite signal to increase an integration interval.

Abstract: Systems and methods of heading determination with global navigation satellite system (GNSS) signal measurements are provided herein. A pair of antennas may be separated by a known baseline length and mounted on a vehicle. A GNSS receiver may obtain pseudorange and carrier phase measurements for GNSS satellites within view. An LRU may estimate carrier phase ambiguities and a two-dimensional vector, using the known baseline length and a linearized measurement model. The LRU may determine integer ambiguities using the estimated carrier phase ambiguities. The LRU may determine assumed wrong fixes of the integer ambiguities and a probability of almost fixed value. The LRU may store the set of integer ambiguities. The LRU may determine, from accumulated data over measurement epochs, updated integer ambiguities. The LRU may correct the carrier phase measurements using the updated integer ambiguities. The LRU may compute the heading using the corrected carrier phase measurements.

Abstract: A receiver device to receive an incoming radio frequency (RF) satellite signal from a satellite vehicle includes a processor and computer-readable storage media. The computer-readable storage media is communicably connected to the processor and has instructions stored thereon that, when executed by the processor, causes the processor to track the incoming RF satellite signal in code phase and carrier frequency, the incoming RF satellite signal having a primary pseudorandom (PRN) code and a secondary PRN code modulated thereon, generate an encoded sequence of dot product values of adjacent integrated in-phase (I) and quadrature-phase (Q) components of the incoming RF satellite signal, compare the encoded sequence with expected secondary code chip transitions, determine a secondary code phase for the secondary PRN code based on the comparison, and coherently integrate the secondary code phase with the incoming RF satellite signal to increase an integration interval.

Abstract: A receiver device to receive an incoming radio frequency (RF) satellite signal from a satellite vehicle includes a processor and computer-readable storage media. The computer-readable storage media is communicably connected to the processor and has instructions stored thereon that, when executed by the processor, causes the processor to track the incoming RF satellite signal in code phase and carrier frequency, the incoming RF satellite signal having a primary pseudorandom (PRN) code and a secondary PRN code modulated thereon, generate an encoded sequence of dot product values of adjacent integrated in-phase (I) and quadrature-phase (Q) components of the incoming RF satellite signal, compare the encoded sequence with expected secondary code chip transitions, determine a secondary code phase for the secondary PRN code based on the comparison, and coherently integrate the secondary code phase with the incoming RF satellite signal to increase an integration interval.

Abstract: Systems and methods of heading determination with global navigation satellite system (GNSS) signal measurements are provided herein. A pair of antennas may be separated by a known baseline length and mounted on a vehicle. A GNSS receiver may obtain pseudorange and carrier phase measurements for GNSS satellites within view. An LRU may estimate carrier phase ambiguities and a two-dimensional vector, using the known baseline length and a linearized measurement model. The LRU may determine integer ambiguities using the estimated carrier phase ambiguities. The LRU may determine assumed wrong fixes of the integer ambiguities and a probability of almost fixed value. The LRU may store the set of integer ambiguities. The LRU may determine, from accumulated data over measurement epochs, updated integer ambiguities. The LRU may correct the carrier phase measurements using the updated integer ambiguities. The LRU may compute the heading using the corrected carrier phase measurements.

Abstract: Systems and methods of heading determination with global navigation satellite system (GNSS) signal measurements are provided herein. A pair of antennas may be separated by a known baseline length and mounted on a vehicle. A GNSS receiver may obtain pseudorange and carrier phase measurements for GNSS satellites within view. An LRU may estimate carrier phase ambiguities and a two-dimensional vector, using the known baseline length and a linearized measurement model. The LRU may determine integer ambiguities using the estimated carrier phase ambiguities. The LRU may determine assumed wrong fixes of the integer ambiguities and a probability of almost fixed value. The LRU may store the set of integer ambiguities. The LRU may determine, from accumulated data over measurement epochs, updated integer ambiguities. The LRU may correct the carrier phase measurements using the updated integer ambiguities. The LRU may compute the heading using the corrected carrier phase measurements.

Abstract: A receiver device to receive an incoming radio frequency (RF) satellite signal from a satellite vehicle includes a processor and computer-readable storage media. The computer-readable storage media is communicably connected to the processor and has instructions stored thereon that, when executed by the processor, causes the processor to track the incoming RF satellite signal in code phase and carrier frequency, the incoming RF satellite signal having a primary pseudorandom (PRN) code and a secondary PRN code modulated thereon, generate an encoded sequence of dot product values of adjacent integrated in-phase (I) and quadrature-phase (Q) components of the incoming RF satellite signal, compare the encoded sequence with expected secondary code chip transitions, determine a secondary code phase for the secondary PRN code based on the comparison, and coherently integrate the secondary code phase with the incoming RF satellite signal to increase an integration interval.

Abstract: The present invention is directed to accurate GPS (global positioning system)-free relative navigation between an unmanned aerial vehicle (UAV) and a tanker aircraft. The UAV transmits a signal which is received by an antenna array at the tanker aircraft. Horizontal relative position of the UAV is determined by calculating range and bearing based on time and phase differences in the received signal. Vertical relative position of the UAV is determined by comparing the altitude of the UAV with the altitude of the tanker aircraft. The tanker aircraft then transmits a navigation solution based on the relative position of the UAV which is received by the UAV. The UAV may utilize the navigation solution transmitted by the tanker aircraft as a backup to a GPS determined navigation solution, in a GPS denied scenario, or in combination with an INS (inertial navigation system) determined navigation solution.

Abstract: A method and apparatus for improving differential navigation accuracy uses time transfer over a two-way communications link. The communications link transmits an overall time offset between a differential reference station and a remote user. A differential navigation position solution is modified at the remote user with the overall time offset to improve the differential navigation accuracy. A first time offset between a first communications device and a first navigation receiver at the remote user is determined. A second time offset between the first communications device at the remote user and a second communications device at the differential reference station is determined. A third time offset between the second communications device and a second navigation receiver at the differential reference station is determined. An overall time offset from the first time offset, the second time offset, and the third time offset is computed and used to improve the differential navigation accuracy.

Abstract: A method and apparatus for improving differential navigation accuracy uses time transfer over a two-way communications link. The communications link transmits an overall time offset between a differential reference station and a remote user. A differential navigation position solution is modified at the remote user with the overall time offset to improve the differential navigation accuracy. A first time offset between a first communications device and a first navigation receiver at the remote user is determined. A second time offset between the first communications device at the remote user and a second communications device at the differential reference station is determined. A third time offset between the second communications device and a second navigation receiver at the differential reference station is determined. An overall time offset from the first time offset, the second time offset, and the third time offset is computed and used to improve the differential navigation accuracy.

Abstract: A vector extended range correlation (ERC) apparatus and method tracks signals transmitted from satellites in a GPS network in extremely low signal to interference plus noise ratio (SINR) environments. A GPS receiver antenna receives the signals transmitted from the satellite, and the signals are converted into digital input signals for each satellite on individual channels. A pseudorange error measurement is generated for each individual channel, and the pseudorange error measurements for all of the individual channels are operated on to generate line-of-sight (LOS) signal tracking commands for each individual channel that are based on the pseudorange error measurements for all of the individual channels. Timing and frequency states for each individual channel are updated based on the LOS signal tracking commands for the respective individual channel.

Abstract: An apparatus and method for mitigating multipath interference in a spread spectrum ranging/positioning system receiver is disclosed. Improved peak tracking in the presence of multipath interference is accomplished with an improved discrimiriant. The discriminant may be developed from a curvilinear function based on a minimal number of correlators. Also disclosed is an open loop measurement compensation innovation that compensates for a multipath-induced shift of the correlation function peak. The positioning system receiver may have either one or both of the mitigation features.