Method and device for rapidly extracting time and frequency parameters from high dynamic direct sequence spread spectrum radio signals under interference

Abstract

A GPS receiver and associated method that embodies high-dynamic, fast acquisition, and interference-suppressing capabilities for the reception and processing of GPS signals from a plurality of GPS satellites to produce GPS signal time and frequency parameters and navigation fixes. The GPS receiver includes an antenna and an analog front-end to intercept the incoming radio-frequency signal, band-limiting amplify the signal, and to convert it to an appropriate intermediate frequency so that it may be converted to digital form. One or more high-speed digital signal processors (DSP) constitute an all digital software baseband processor that process the sampled and quantified signals to form a two-dimensional delay-Doppler map of correlation power and to extract the signal time and frequency parameters and navigation data. The baseband processor is organized into functionally identical channels, each dynamically assigned to a different satellite visible. The baseband processor performs the incoming signal time-tagging, transformation, replica generation, interference-suppressing, delay-Doppler mapping and frequency uncertainty planning. The baseband processor also performs integration for larger processing gain, parameter extraction, and operational management. A relatively slow-speed microprocessor, coupled to the baseband processor, integrates the signal time and frequency parameters and navigation data from a plurality of GPS satellites to produce a navigation solution by a Kalman filter or a least-squares estimator.