A Hardware Implementation for a New Post-correlation Anti-jamming Method
- PDF / 2,195,992 Bytes
- 20 Pages / 439.37 x 666.142 pts Page_size
- 20 Downloads / 153 Views
A Hardware Implementation for a New Post‑correlation Anti‑jamming Method M. Aghadadashfam1 · A. Ramezani1 · M. R. Mosavi1 Accepted: 11 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract This paper describes the design and development of field programmable gate arrays based anti-jamming hardware. The key function of the system involves a new post-correlation filtering system to provide an anti-jamming feature in GPS receivers. The proper filter is applied to the values of the cross-ambiguity function in the search space, which decreases interference signal contribution without any need for prior knowledge of its specific characteristics. The structure is implemented and evaluated on the Xilinx ZedBoard which uses an XC7Z020 chip as the main processing unit. The design of the proposed filter structure is fully pipelined. It can be easily integrated with the acquisition system. By using this method, the receiver is capable of acquiring four satellites and successfully positioning in the presence of continuous wave interference with JSR up to 50 dB. The resource usage of the design is independent of the correlation output size. This can reduce the number of resources used and the computational burden greatly. Keywords De-noising · Interference mitigation · Jamming · Acquisition · FPGA
1 Introduction The global positioning system (GPS) signals received in the antenna of receivers are below the noise floor. That is why GPS signals are consequently vulnerable to noise and interference. For this reason, interference mitigation and acquiring weak signals in the presence of the interference is an important problem for GPS receivers. Jamming cancellation techniques for standard GPS receiver can be classified into two groups: (1) post-correlation methods and (2) pre-correlation techniques [1].
* M. R. Mosavi [email protected] M. Aghadadashfam [email protected] A. Ramezani [email protected] 1
Department of Electrical Engineering, Iran University of Science and Technology, Narmak, Tehran 16846‑13114, Iran
13
Vol.:(0123456789)
M. Aghadadashfam et al.
The purpose of the acquisition phase is to detect GPS signals for satellites in line of sight. To achieve this goal, the receiver needs to provide a rough estimate of code delay and Doppler frequency values of the received signal and then transmit the information to the tracking loops. First, the output signal from the ADC converter is multiplied by a local carrier. The local carrier is composed of two orthogonal sinusoids with various frequencies. Second, this product is multiplied by the replica code delayed by 𝜏 , and then the result is coherently integrated over a fixed period. Concerning the local carrier has two components of sine and cosine, the result is a complex function [2]. With this assumption for each PRN code, we have a search space matrix (CAF matrix) of Doppler frequency bins × code phases dimensions. The values of the search space or the CAF matrix )are the complex ( modulus
Data Loading...
