Title :
Efficient Real-Time Generation of Bit-Wise Parallel Representations of Oversampled Carrier Replicas
Author :
Ledvina, Brent M.
Author_Institution :
Bradley Dept. of Electr. & Comput. Eng., Virginia Polytech. Inst. & State Univ., Blacksburg, VA, USA
fDate :
10/1/2011 12:00:00 AM
Abstract :
An algorithm has been developed that efficiently generates in-phase and quadrature carrier replicas over a range of Doppler shift frequencies and initial phase offsets. This algorithm provides a new method that aids in bit-wise parallel baseband mixing of signals in software radios, specifically targeted at GNSS radios. Bit-wise parallel correlation, of which one step is baseband mixing, provides a processing time speed-up when correlating signals that are digitized to a low number of bits, as opposed to the standard multiply-and-accumulate correlation. The new algorithm makes use of the small phase differences between a set of signals that have a large ratio of the IF to the Doppler shift frequency. It uses specially-designed look-up tables to generate carrier replicas on-the-fly. This new algorithm can efficiently generate bit-packed carrier replicas using a small look-up table (10-100 s of kBytes).
Keywords :
Doppler shift; correlation methods; satellite navigation; software radio; table lookup; Doppler shift frequency; GNSS radio; bit-wise parallel correlation baseband mixing signal; bit-wise parallel representation real-time generation; in-phase carrier replica; initial phase offset; oversampled carrier replica; quadrature carrier replica; signals correlation; small phase difference; software radio; specially-designed look-up table; standard multiply-and-accumulate correlation; Basebane; Doppler measurements; Doppler shift; Quadrature phase shift keying; Real time systems; Software algorithms;
Journal_Title :
Aerospace and Electronic Systems, IEEE Transactions on
DOI :
10.1109/TAES.2011.6034674