Pillsbury Winthrop Shaw Pitman LLP
Methods and systems for acquisition, reacquisiton and tracking of weak navigational signals
Provided herein are systems and methods for achieving long coherent integration in a navigational receiver to improve the sensitivity of the receiver and enable the receiver to acquire, reacquire and track signals under very weak signal conditions. In an embodiment, phase compensation is computed based on estimated Doppler frequency, rate of change of the Doppler frequency with time, and second order rate of change of the Doppler frequency. The Doppler frequency may be computed from an orbital model or ephemeris. This phase compensation is used to compensate samples of the input signal for changes in the phase due to the Doppler frequency. Frequency components of the phase-compensated samples are then computed using a frequency analysis such as a Fast Fourier Transform (FFT). The maximum frequency component is taken as an error frequency and used to compensate the samples of the input signal for residual frequency error.
SiRF Technology Holdings, Inc.
G H G
G01S H04B G01S
inventional inventional inventional
Chi-Shin EnYuan Jian Zhike Yue-Meng
Wang Tu Cheng Jia Chen