Patent ID: 7995676
Filing Date: 2011-08-09
Classification: H04B,H04L

Abstract:
1. A method for signal acquisition, comprising: (a) receiving a sampled complex baseband signal representative of a complex envelope of a received signal; (b) low-pass filtering the received sampled signal to generate a filtered sampled signal; (c) decimating the filtered sampled signal to reduce a sample rate thereof; (d) cross-correlating the decimated filtered sampled signal in time and frequency with a locally-generated replica thereof to generate a sampled cross ambiguity function (CAF) having samples spaced in time according to the sample rate of the decimated filtered sampled signal; (e) interpolating the sampled CAF in time and frequency over the entirety of a time-frequency domain of the sampled CAF to generate a second CAF, wherein the second CAF has at least two times a number of samples as the sampled CAF, and wherein said interpolating comprises interpolating complex-valued samples of the sampled CAF, thereby performing a coherent interpolation of the sampled CAF; (f) detecting a correlation peak in the second CAF; wherein said detecting comprises applying a common peak detection threshold to both interpolated and non-interpolated samples of the second CAF; and (g) estimating a peak value of the detected correlation peak, wherein the peak value corresponds to an estimated pair of time and frequency offsets between the filtered sampled signal and the locally generated replica.