The Effect of Notch Filter on RFI Suppression

Chang, Wenge; Li, Jian‐Yang; Li, Xiangyang

doi:10.4236/wsn.2009.13026

Cited by 10 publications

(8 citation statements)

References 5 publications

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“…Notch filtering is an easy to implement, widely used, and very effective method for RFI suppression in SAR data [22]. Despite its effectiveness, notch filtering can have adverse effects on the imaging performance that depends on the width of the applied notch.…”

Section: F Rfi Mitigationmentioning

confidence: 99%

“…Despite its effectiveness, notch filtering can have adverse effects on the imaging performance that depends on the width of the applied notch. For instance, it can be shown that notch filtering can lead to an increase of sidelobe levels in focused SAR images and may decrease the data's signal-tonoise ratio [22]. Still, notch filtering has been the method of choice for effective and efficient RFI suppression of many operational SAR systems such as ALOS PALSAR [1].…”

Section: F Rfi Mitigationmentioning

confidence: 99%

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Correction and Characterization of Radio Frequency Interference Signatures in L-Band Synthetic Aperture Radar Data

Meyer

Nicoll

Doulgeris

2013

IEEE Trans. Geosci. Remote Sensing

120

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Radio frequency interference (RFI) is a known issuein low-frequency radar remote sensing. In synthetic aperture radar (SAR) image processing, RFI can cause severe degradation of image quality, distortion of polarimetric signatures, and an increase of the SAR phase noise level. To address this issue, a processing system was developed that is capable of reliably detecting, characterizing, and mitigating RFI signatures in SAR observations. In addition to being the basis for image correction, the robust RFI-detection algorithms developed in this paper are used to retrieve a wealth of RFI-related information that allows for mapping, characterizing, and classifying RFI signatures across large spatial scales. The extracted RFI information is expected to be valuable input for SAR-system design, sensor operations, and the development of effective RFI-mitigation strategies. The concepts of RFI detection, analysis, and mapping are outlined. Large-scale RFI mapping results are shown. In case studies, the benefit of detailed RFI information for customized RFI filtering and sensor operations is exemplified.Index Terms-Calibration, error correction, L-band, radar remote sensing, radio frequency interference (RFI), synthetic aperture radar (SAR). I. INTRODUCTIONR ADIO frequency interference (RFI) has long been identified as a problem in L-band synthetic aperture radar (SAR), limiting the performance, and applicable signal bandwidth of SAR in many areas around the globe [1]. Most RFI are incoherent electromagnetic interference signals emitted by communication systems, television networks, air-traffic surveillance radars, and other mainly military-based radiation sources whose operating frequency overlaps with the frequency band of a SAR system. RFI usually appear as various kinds of bright linear features in the azimuth-time rangefrequency diagram of a SAR dataset and the interference-to-SAR signal ratio is often high. Incoherent RFI will be partly mitigated by the matched filter process that is applied in the SAR image focusing due to Manuscript

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Section: F Rfi Mitigationmentioning

confidence: 99%

Section: F Rfi Mitigationmentioning

confidence: 99%

Correction and Characterization of Radio Frequency Interference Signatures in L-Band Synthetic Aperture Radar Data

Meyer

Nicoll

Doulgeris

2013

IEEE Trans. Geosci. Remote Sensing

120

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“…In the days of analogue TV, the interference to lowfrequency radar was narrow-band, and hence easy to cope with, for example by notch filtering [4], adaptive LMS filtering [5], or by utilizing the structure of the signal [6]. However, since the dawn of digital TV, and more specifically terrestrial digital TV broadcast, the interference is wide-band.…”

Section: Introductionmentioning

confidence: 97%

DVB-T interference cancellation in radar signal processing

Svensson

McKelvey

Hellsten³

2014

2014 International Radar Conference

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In this paper, a novel filter for cancellation of DVB-T interference in low-frequency synthetic aperture radar systems is presented. The filter relies on using the pilots in the DVB-T signal to estimate the communications channel between the broadcast antenna and the flying radar system. Then, by decoding and re-coding the interference signal, it can be subtracted from the combined radar and TV signal. Simulation results indicate good performance in relevant signal-to-interference ratios.

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“…Conventional RFI mitigation techniques can be grouped into three categories [6][7][8][9]: notching methods, subtraction methods and filter methods. Conventional notching methods remove samples from the data that are corrupted by RFI.…”

Section: Introductionmentioning

confidence: 99%

“…The advantage of notching is the fast implementation at a low computational cost. Disadvantages include SNR drop due to a loss of part of the desired signal, an inevitable distortion of the SAR Impulse Response Function (IRF) and an increase of its sidelobes [8]. The subtraction methods aim at estimating and modelling the RFI based on a priori information [7,10,11].…”

Section: Introductionmentioning

confidence: 99%

Adaptive Antenna Pattern Notching of Interference in Synthetic Aperture Radar Data Using Digital Beamforming

et al. 2019

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Radio Frequency Interference (RFI) is a growing problem in Synthetic Aperture Radar (SAR) systems as scientific motivations push the radars to lower frequencies and as more wireless services share the frequency spectrum. New, advanced SAR instruments, such as NASA’s EcoSAR, DBSAR and DLR’s Tandem-L mission, employ a multichannel architecture capable of Digital Beamforming (DBF). Radars with DBF are capable of notching the antenna pattern in specific directions, which can be utilized to suppress RFI on board or in post-processing. A well-researched beamformer for this purpose is the Minimum Variance Distortionless Response (MVDR) Beamformer. However, the number of interferers that can be removed through notching is limited by the number of receive channels. It is therefore essential to adaptively change the antenna pattern notching throughout the image in time and frequency for the best results with a given number of receive channels. In this paper, we present several methods to achieve this notching by making use of the spatial SAR signal distribution in range time, range frequency, azimuth time and azimuth Doppler that is inherent to the SAR imaging geometry. Because this distribution is time-variable and yet predictable, it can be used to improve the angle of arrival estimation of the RFI and the adaptive notching. The presented methods can be applied to a Digital Beamforming (DBF) SAR signal with multiple channels in elevation and/or in azimuth. Simulations show that the proposed methods increase the ability to notch out-of-swath interference from multiple directions and lessen the impact on in-swath interference. The improvement of the interferometric coherence for a single-pass interferogram acquired by NASA’s EcoSAR system (capable of DBF in elevation) is demonstrated. The removal of periodic RFI artifacts is achieved.

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The Effect of Notch Filter on RFI Suppression

Cited by 10 publications

References 5 publications

Correction and Characterization of Radio Frequency Interference Signatures in L-Band Synthetic Aperture Radar Data

Correction and Characterization of Radio Frequency Interference Signatures in L-Band Synthetic Aperture Radar Data

DVB-T interference cancellation in radar signal processing

Adaptive Antenna Pattern Notching of Interference in Synthetic Aperture Radar Data Using Digital Beamforming

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