Acquisition of Galileo Signals in Hybrid Double-dwell Approaches

Double-dwell acquisition structures have typically been proposed as better alternatives to single-dwell structures from the point of view of the Mean Acquisition Time (MAT). Traditional approaches divide the double-dwell structure into an acquisition stage with short integration time, followed by a verification stage with longer integration time, which should provide a smaller global false alarm probability than a single-dwell structure (i.e., only the acquisition stage). However, if we fix from the beginning the global detection probability and the global false alarm probability, little is known about how to design the parameters of the double-dwell structure (i.e., detection and false alarm probabilities at each stage) for a minimum MAT, and under which conditions (if any), the double-dwell structure is better than a singledwell structure aiming at exactly the same global detection probability and global false alarm probability. This paper proposes a comprehensive analysis of the choice of detection and false alarm probabilities at each stage of a doubledwell structures for a realistic Galileo signal with Binary-Offset-Carrier BOC(1,1) modulation and 10230-chip length pseudorandom codes. We also present here the conditions under which a double-dwell structure is indeed better (from MAT point of view) than a single-dwell structure and we discuss the steps to be taken in the design process of the double-dwell acquisition structure.