No Access

Department of Electrical & Electronic Engineering, Stellenbosch University, South Africa

Corresponding author.

Search for more papers by this author

David B. Davidson

Department of Electrical & Electronic Engineering, Stellenbosch University, South Africa

International Centre for Radio Astronomy Research (ICRAR), Curtin University, Australia

Search for more papers by this author

, and

Stefan J. Wijnholds

Department of Electrical & Electronic Engineering, Stellenbosch University, South Africa

Netherlands Institute for Radio Astronomy (ASTRON), The Netherlands

Search for more papers by this author

https://doi.org/10.1142/S2251171719400130Cited by:1 (Source: Crossref)

This article is part of the issue:

Special Issue — Interference Mitigation Techniques in Radio Astronomy; Guest Editors: Kaushal D. Buch, Albert-Jan Boonstra, Gregory Hellbourg, Jonathon Kocz and Urvashi Rau

View article

Abstract

In a recent paper, we presented a non-narrowband spatial radio frequency interference (RFI) mitigation algorithm for radio astronomy arrays. The algorithm constructs a 2nd-order filter by combining a 1st-order subspace subtraction method with a non-narrowband signal model. The model is based on the assumption that the frequency response is approximately flat and that the array is calibrated. In this paper, we consider the effects of array imperfections such as unknown complex gains and mutual coupling, incorporate these into the non-narrowband signal model and extend the RFI mitigation algorithm to include a calibration step. With a calibration step and no mutual coupling, the proposed algorithm was able to process twice the bandwidth per channel when compared to conventional narrowband techniques. This performance declines to 1.6 times greater bandwidth when the effect of mutual coupling is included. The evaluation of the algorithm was done using the layout of a Low Frequency Array (LOFAR) High Band Antenna (HBA) station and a digital audio broadcast recorded with a software defined radio.

Keywords:

References

Balanis, C. A. & Ioannides, P. I. [2007] Introduction to Smart Antennas (Morgan & Claypool Publishers). Crossref, Google Scholar
Boonstra, A. J. [2005] Radio Frequency Interference Mitigation in Radio Astronomy, PhD Thesis, Delft University of Technology. Google Scholar
Bridle, A. H. & Schwab, F. R. [1999] Bandwidth and Time-Average Smearing, in G. B. Taylor, C. L. Carilli and R. A. Perley, editors, “Synthesis Imaging in Radio Astronomy II,” 180, 18, pp. 371–382. Google Scholar
Brossard, M., El Korso, M. N., Pesaventoc, M., Boyer, R., Larzabal, P. & Wijnholds, S. J. [2018] “Parallel multi-wavelength calibration algorithm for radio astronomical arrays,” Signal Process. 145, 258–271. https://doi.org/10.1016/j.sigpro.2017.12.014 Crossref, ADS, Google Scholar
Compton, R. T. [1988] Adaptive Antennas: Concepts and Performance (Prentice-Hall). Google Scholar
de Gasperin, F., Mevius, M., Rafferty, D. A., Intema, H. T. & Fallows, R. A. [2018] “The effect of the ionosphere on ultra-low-frequency radio-interferometric observations,” A&A 615(A179). https://doi.org/10.1051/0004-6361/201833012 Google Scholar
Herdin, M., Czink, N., Ozcelik, H. & Bonek, E. [2005] “Correlation matrix distance, a meaningful measure for evaluation of non-stationary MIMO channels,” IEEE 61st Vehicular Technology Conf., Stockholm, Sweden. https://doi.org/10.1109/VETECS.2005.1543265 Google Scholar
Johnson, D. H. & Dudgeon, D. E. [1993] Array Signal Processing: Concepts and Techniques (Prentice-Hall, NJ). Google Scholar
Salvini, S. & Wijnholds, S. J. [2014] “Fast gain calibration in radio astronomy using alternating direction implicit methods: Analysis and applications,” A&A 571, 1–14. https://doi.org/10.1051/0004-6361/201424487 Crossref, Google Scholar
Sardarabadi, A. M. [2016] Covariance Matching Techniques for Radio Astronomy, PhD Thesis, Delft University of Technology. Google Scholar
Steeb, J. W., Davidson, D. B. & Wijnholds, S. J. [2018] “Mitigation of non-narrowband radio frequency interference”, Radio Sci. Bull. 2018, 10–19. https://doi.org/10.23919/URSIRSB.2018.8572495 Crossref, ADS, Google Scholar
Thompson, A. R., Moran, J. A. & Swenson Jr. G. W. [2004] Interferometry and Synthesis in Radio Astronomy Second Edition (WILEY-VCH Verlag GmbH & Co. KGaA). https://doi.org/10.1002/9783527617845 Google Scholar
van der Tol, S. & van der Veen, A. [2005] “Performance analysis of spatial filtering of RF interference in radio astronomy,” IEEE Transactions on Signal Processing 53(3), 896–910. https://doi.org/10.1109/TSP.2004.842177 Crossref, ADS, Google Scholar
van der Veen, A., Leshem, A. & Boonstra, A. [2004] “Signal processing for radio astronomical arrays,” in Proc. Sensor Array and Multichannel Signal Processing Workshop, pp. 1–10. https://doi.org/10.1109/SAM.2004.1502901 Google Scholar
van Haarlem, M. P. et al. [2013] “LOFAR: The low frequency array,” A&A 556, A2, 1–53. https://doi.org/10.1051/0004-6361/201220873 Google Scholar
Warnick, K., Maaskant, R., Ivashina, M., Davidson, D. & Jeffs, B. [2018] “, Transmitting arrays, network analysis, and pattern overlap integrals, ” in Phased Arrays for Radio Astronomy, Remote Sensing, and Satellite Communications, EuMA High Frequency Technologies Series (Cambridge University Press, Cambridge), pp. 106–153. https://doi.org/10.1017/9781108539258.005 Crossref, Google Scholar
Wijnholds, S. J. [2008] Mutual Coupling, Inter-Tile Spacing and Inter-Station Rotation in the HBA Array, Technical Report, LOFAR-ASTRON-MEM-245. Google Scholar
Yuen, N. & Friedlander, B. [1998] “Performance analysis of higher order ESPRIT for localization of near-field sources,” IEEE Transactions on Signal Processing 46(3), 709–719. https://doi.org/10.1049/ip-rsn:19981670 Crossref, ADS, Google Scholar
Zatman, M. [1998] “How narrow is narrowband?” IEE Proc. Radar, Sonar and Navigation 145(2), 85–91. https://doi.org/10.1109/78.661337 Crossref, Google Scholar