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Abstract

A digital signal processing system for obtaining accurate time delay of arrival (TDOA) and frequency delay of arrival (FDOA) measuremets of a signal of interest in a dense interfering signal environment is provided. A time series of cross-spectra (called a waterfall in the art) are computed from transforms applied to overlapping data sets comprising two received digital data streams, which include the signal from an emitter of interest and one or more partially overlapping interfering signals. For each cross-spectra frequency, a transform is calculated in the time direction to create a frequency difference of arrival dimension. Regions within the transformed cross-spectrum that are associated with individual emitters are then identified based on the fact that a given emitter's transformed cross-spectrum phase changes linearly with frequency near the peak FDOA for the emitter. The frequency region(s) associated with the emitter of interest are selected based on the approximate frequency and bandwidth information provided. Applying an inverse transform for the frequencies, identified as associated with the emitter of interest, creates a time difference of arrival dimension corresponding to each frequency difference of arrival value.

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First Claim