Abstract: A method and apparatus are provided for processing navigation signals with improved stability in a multi-frequency, multi-system environment. Satellite signals, which are transmitted by a plurality of satellites from a plurality of different global navigation satellite systems, are received on a common radio path and processed in separate digital satellite channels, with each of the separate digital satellite channels corresponding to a respective satellite signal. A common quartz-locked-loop (QLL) discriminator signal is generated based on correlation signals from each of the separate digital satellite channels. Based on the common QLL discriminator signal, guiding signals are generated, with each of the guiding signals corresponding to a respective one of the separate digital satellite channels, for reducing phase-related tracking errors in the respective satellite signal processed in its corresponding digital satellite channel.

Abstract: A method and system are provided for estimating the g-sensitivity of a quartz oscillator, which includes rotating the quartz oscillator successively around each of a plurality of axes constituting a full-rank system, measuring a frequency of the quartz oscillator at a predetermined rate as a function of time during rotation, and estimating an integral g-sensitivity vector while the quartz oscillator is rotated. Estimation can be performed utilizing a data fitting and estimation model, e.g., a Least Square Method (LSM) in one example, using the frequency measurements obtained while the quartz oscillator is in rotation around the axes. The method and system are especially useful for measuring g-sensitivity of quartz oscillators that are incorporated in high-precision systems, such as navigation receivers, which operate in environments that are subjected to vibrational effects and other mechanical forces.

Abstract: A method and system are provided for estimating the g-sensitivity of a quartz oscillator, which includes rotating the quartz oscillator successively around each of a plurality of axes constituting a full-rank system, measuring a frequency of the quartz oscillator at a predetermined rate as a function of time during rotation, and estimating an integral g-sensitivity vector while the quartz oscillator is rotated. Estimation can be performed utilizing a data fitting and estimation model, e.g., a Least Square Method (LSM) in one example, using the frequency measurements obtained while the quartz oscillator is in rotation around the axes. The method and system are especially useful for measuring g-sensitivity of quartz oscillators that are incorporated in high-precision systems, such as navigation receivers, which operate in environments that are subjected to vibrational effects and other mechanical forces.

Abstract: A navigation receiver operably coupled to an antenna can determine location by receiving and processing radiofrequency navigation signals from global navigation satellites. The navigation receiver includes a quartz crystal oscillator that serves as a reference frequency source for a local oscillator signal that is mixed with the radiofrequency navigation signals to generate intermediate signals at intermediate frequencies lower than the radiofrequencies. In particular applications, the quartz crystal oscillator and the antenna are subjected to vibration and shock. A shift in the frequency or phase of the intermediate signals can result, and performance of phase-lock loops can degrade. Performance is improved with a phase-lock loop that processes a combination of individual channel control signals and common control signals.

Abstract: A correction phase locked loop (CPLL), including a signal processing unit that receives a digitized input signal from a satellite, the signal processing unit comprising (a) a primary correlator and primary discriminator, connected in series and generating a main error signal Z1 from the digitized input signal; (b) a correction correlator and a correction discriminator connected in series and generating a correction signal Z2; and (c) an adder for adding the main error signal Z1 and the correction signal Z2 to produce a common error signal Z. A loop filter filters the common error signal Z to produce a corrected error signal that is used for frequency-phase control of a Numerical Control Oscillator (NCO). The NCO generates two mutually orthogonal output reference signals whose phase is substantially free of multipath errors.

Abstract: A correction phase locked loop (CPLL), including a signal processing unit that receives a digitized input signal from a satellite, the signal processing unit comprising (a) a primary correlator and primary discriminator, connected in series and generating a main error signal Z1 from the digitized input signal; (b) a correction correlator and a correction discriminator connected in series and generating a correction signal Z2; and (c) an adder for adding the main error signal Z1 and the correction signal Z2 to produce a common error signal Z. A loop filter filters the common error signal Z to produce a corrected error signal that is used for frequency-phase control of a Numerical Control Oscillator (NCO). The NCO generates two mutually orthogonal output reference signals whose phase is substantially free of multipath errors.

Abstract: A navigation receiver operably coupled to an antenna can determine location by receiving and processing radiofrequency navigation signals from global navigation satellites. The navigation receiver includes a quartz crystal oscillator that serves as a reference frequency source for a local oscillator signal that is mixed with the radiofrequency navigation signals to generate intermediate signals at intermediate frequencies lower than the radiofrequencies. In particular applications, the quartz crystal oscillator and the antenna are subjected to vibration and shock. A shift in the frequency or phase of the intermediate signals can result, and performance of phase-lock loops can degrade. Performance is improved with a phase-lock loop that processes a combination of individual channel control signals and common control signals.

Abstract: The energy potential of a receiver receiving signals from a navigation satellite is calculated according to an algorithm which is a function of an estimate of the mean and an estimate of the variance of a correlation signal. Improving the accuracy of measuring the energy potential may be achieved by improving the variance estimate. The variance estimate may be determined from measurements of the correlation signal over long time intervals during operation of the receiver. The variance estimate may also be determined during a calibration procedure, or by mathematical modeling of the receiver.

Abstract: The energy potential of a receiver receiving signals from a navigation satellite is calculated according to an algorithm which is a function of an estimate of the mean and an estimate of the variance of a correlation signal. Improving the accuracy of measuring the energy potential may be achieved by improving the variance estimate. The variance estimate may be determined from measurements of the correlation signal over long time intervals during operation of the receiver. The variance estimate may also be determined during a calibration procedure, or by mathematical modeling of the receiver.