An innovative FPGA‐based low‐complexity and multi‐constellations compatible GNSS acquisition scheme

Abstract

There is a strong demand for the multi-constellations compatible Global Navigation Satellite System (GNSS) acquisition scheme, since it is able to acquire signals from different constellations to increase availability of satellites. However, the presence of multiple modulation modes and diverse Pseudo-Random-Noise (PRN) code lengths makes the design challenging. Moreover, existing schemes consume a lot of hardware resources. Hence, we present an innovative Field Programmable Gate Array (FPGA)-based lowcomplexity and multi-constellation compatible GNSS acquisition scheme to provide a solution for the above-mentioned challenges. This scheme is based on the proposed Improved Serial-Parallel Matched Filter structure that not only requires less hardware resources than conventional structures but also performs all operations in a pipeline to simplify the implementation in FPGA. Additionally, the maximum likelihood criterion is used to obtain decision statistics, which ensures the compatibility between BPSK and sBOC (1,1) signals. Furthermore, a three-step method to acquire signals with a long PRN code is proposed. This also guarantees the compatibility among signals with different PRN code lengths. Finally, a new aided acquisition method to accelerate the acquisition process of signals with a long PRN code is proposed. Experimental results show this scheme is capable of acquiring multi-constellations civil GNSS signals, and therefore it has high practical value. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

An Innovative Signal Processing Scheme for Spaceborne Integrated GNSS Remote Sensors

“…Moreover, the coherent integration time is also 1 ms for the Galileo E1B signal, although its PRN code period is 4 ms, which merely leads to a slight degradation in its ACF gain and no obvious influence on its DDM data. It is of significant convenience for the low-complexity compatible design of the GNSS-R module that the above-mentioned three-aspect strategies are employed [29]. Since the ACF of the Galileo E1B signal has two side peaks and these two side peaks are not only a half primary chip away from the main peak but also have values reaching half of the ACF value of the main peak, two side peaks have a special effect on the delayed waveforms in the DDM.…”

Interferometer direction‐finding system with time‐division multiplexing of spread spectrum signals

“…Thus, the system uses a spread spectrum receiving system. 9,10 Regardless of the influence of data bits, the transmitted signal is as shown in (8).…”

“…$$$e({\hat{N}}_{1},{\hat{N}}_{2})={d}_{2}[2\pi {\hat{N}}_{1}+{\varphi }_{1}]-{d}_{1}[2\pi {\hat{N}}_{2}+{\varphi }_{2}].$$$Compared with the traditional interferometer, the spread spectrum receiver can effectively improve the noise‐immune and antijamming capability. Thus, the system uses a spread spectrum receiving system 9,10 . Regardless of the influence of data bits, the transmitted signal is as shown in ().…”