Abstract: A positioning signal from a satellite positioning system is received at a mobile station, correction information from a reference station is used, a pseudo distance observation formula using a code and a phase distance observation formula using a carrier wave are used to perform positioning using single frequency at the mobile station, and these observation formulas are expressed by a satellite clock error, clock errors at the reference station and the mobile station, a ionospheric delay and a tropospheric delay, and a code bias and a phase bias of single frequency at the reference station, the mobile station and a satellite.

Abstract: A positioning signal from a satellite positioning system is received at a mobile station, correction information from a reference station is used, a pseudo distance observation formula using a code and a phase distance observation formula using a carrier wave are used to perform positioning using single frequency at the mobile station, and these observation formulas are expressed by a satellite clock error, clock errors at the reference station and the mobile station, a ionospheric delay and a tropospheric delay, and a code bias and a phase bias of single frequency at the reference station, the mobile station and a satellite.

Abstract: Methods and systems for demodulation of open-loop GPS radio occultation signals are provided. An occulted GPS radio signal where the atmosphere-induced modulation on the phase is up to 180 degrees may be recorded by a radio occultation receiver. The radio signal may be concurrently received by a second receiver where the atmosphere-induced phase modulation is below 90 degrees and where the Navigation Data Message (NDM) bit sequence can be readily extracted. The extracted NDM bit sequence may be used to demodulate the occulted GPS radio signal and a 4-quadrant phase extractor may then be used to determine the phase and amplitude of the radio occultation signal. The phase and amplitude modulations after removal of NDM may be used for inversion, e.g., retrieval of the atmospheric parameters such as the bending angle, refractivity and deriving of the meteorological parameters.

Abstract: Methods and systems for demodulation of open-loop GPS radio occultation signals are provided. An occulted GPS radio signal where the atmosphere-induced modulation on the phase is up to 180 degrees may be recorded by a radio occultation receiver. The radio signal may be concurrently received by a second receiver where the atmosphere-induced phase modulation is below 90 degrees and where the Navigation Data Message (NDM) bit sequence can be readily extracted. The extracted NDM bit sequence may be used to demodulate the occulted GPS radio signal and a 4-quadrant phase extractor may then be used to determine the phase and amplitude of the radio occultation signal. The phase and amplitude modulations after removal of NDM may be used for inversion, e.g., retrieval of the atmospheric parameters such as the bending angle, refractivity and deriving of the meteorological parameters.

Abstract: A method of compensating for atmospheric effects to detect the actual location of low elevation objects using near horizon radar to detect an object which utilizes a preexisting satellite structured to send a signal indicating the position and velocity of said satellite, wherein the location of the satellite is known. The method includes a step of providing a radar site, a first receiver structured to receive a signal from the satellite indicating an apparent location of the satellite, and a second receiver, located at a distance from the radar site, structured to receive the satellite signal and which indicates the observed location of the satellite. The first receiver is utilized to receive a signal from the satellite when the satellite is at a low elevation. This signal indicates the apparent location and velocity of the satellite.

Abstract: The present system for determining the phase and amplitude of a radio occultation signal modifies the traditional Open Loop tracking process to maximize the signal-to-noise ratio, minimize the sampling rate, and also preserve the structure of the radio occultation signals. A radio occultation system includes a transmitter system, a receiver system, and a post-processing system. The receiver system receives the radio signal that is transmitted by the transmitter system through the earth's atmosphere, where it is occulted, and down converts the received radio occultation signal to generate a down converted signal based on a phase model that uses a refractivity climatology. The receiver system then low pass filters the down converted signal and samples the in-phase and quadrature components of the down converted and low pass filtered signal.

Abstract: The present system for determining the phase and amplitude of a radio occultation signal modifies the traditional Open Loop tracking process to maximize the signal-to-noise ratio, minimize the sampling rate, and also preserve the structure of the radio occultation signals. A radio occultation system includes a transmitter system, a receiver system, and a post-processing system. The receiver system receives the radio signal that is transmitted by the transmitter system through the earth's atmosphere, where it is occulted, and down converts the received radio occultation signal to generate a down converted signal based on a phase model that uses a refractivity climatology. The receiver system then low pass filters the down converted signal and samples the in-phase and quadrature components of the down converted and low pass filtered signal.

Abstract: A Global Positioning System includes a ground monitoring network having a plurality of dual frequency receivers that obtain ionospheric delay measurements to provide double difference ionospheric delay residuals. These double difference delay residuals are converted to zero differences based upon a new mathematical technique. The zero differences are fit to measurement epoch specific and transmitter specific mathematical surfaces (i.e. planes). These planes represent precise ionospheric delay corrections in the area of the ground monitoring network for a specific transmitter at the measurement epoch. The planes are then provided as correction information for use by inexpensive single frequency receivers to obtain highly accurate corrections for single frequency receivers by interpolating the correction planes to the location of the single frequency receiver.

Abstract: An atmospheric water vapor sensing system uses Global Positioning Satellites (GPS) to determine the refractivity and Slant-path Water Vapor Delay (SWD) between an Earth-based GPS receiver and a plurality of satellite-based GPS transmitters. The system provides improved precision in position calculation measurements by eliminating the refractivity effects of water vapor. No other system inputs are required apart from conventional GPS satellite signals and conventional satellite orbit data to implement the method. SWD arises from the refractivity in the integrated atmospheric water vapor in a column of atmosphere at an acute angular line-of-sight path between the Earth-based GPS receiver and any one of the plurality of satellite-based GPS transmitters. The system is especially useful in monitoring the Earth's crustal deformation.