Transform Domain Interference Suppression in GPS/BD-2 Receiver Based on Fractional Fourier Transforms

Y. Zhang, H. Wu, Y. Gao

Abstract:	The presence of disturbing signal such as spurious, harmonics and electromagnetic interferences can represent a serious threat for both civil and professional GNSS receiver whose performance can be severely limited and degraded. Although,Global Navigation Satellite System has certain capability of immunity from interference since Direct Sequence Spread Spectrum (DSSS) is utilized in GNSS, while anti-jamming technology is needed to ensure the performance of GNSS receiver under strong interferences. In GNSS receiver application, less computationally demanding interference mitigation techniques, such as temporal adaptive filter, notch filter, and frequency excision are applied. Although those method is simple to realization on GNSS baseband chip, use of these detection/mitigation techniques is often confined a specific class signal such as Gaussian narrowband and continuous wave interference signal. Due to the interference signals encountered in practice are not only stationary, above methods will become disabled. In this paper, a time frequency transform domain interference suppression in GPS/BD-2 receiver based on Fractional Fourier Transform(FrFT)is presented, which is the efficient analysis accomplished in non-stationary interference signal in order to improve the time-frequency resolution with minimum cross-term interference. Transform domain interference suppression have the advantages of fast convergence rate, real-time ability and can suppress multiple interference simultaneously than time domain interference suppression. But traditional transform radix is difficult to achieve better focusing properties under various jamming, especially pectinate or chirp jamming. The transform domain interference suppression based on FrFT represents the general characterization from the time domain to the frequency domain. In particular, a solution for efficient implementing in GPS/BD-2 receiver chip is proposed. Through pattern recognition with jamming types, this method can suppress the interference at corresponding fractional order where the energy spectrum have best focused effect, for the narrow-band and multi-tone interference use FFT while for the pectinate and chirp interference FrFT is adapted. More specifically, by using the method, it is shown that the interference such as narrow-band, multi-tone, pectinate and chirp interference are recognized easily in the frequency domain and excision is realized in frequency domain by the test of GPS/BD-2 receiver under the interference.The result validates that this method has a well interference suppressing capability.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	3456 - 3463
Cite this article:	Zhang, Y., Wu, H., Gao, Y., "Transform Domain Interference Suppression in GPS/BD-2 Receiver Based on Fractional Fourier Transforms," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 3456-3463.
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