Although pulse compression optical time domain reflectometry (PC-OTDR) exhibits high performance in spatial resolution and dynamic range, it inevitably introduces auto-correlation sidelobes, potentially impacting meas...
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Although pulse compression optical time domain reflectometry (PC-OTDR) exhibits high performance in spatial resolution and dynamic range, it inevitably introduces auto-correlation sidelobes, potentially impacting measurement accuracy. In this letter, an improved clean algorithm is proposed to efficiently suppress sidelobes and enhance the peak-to-sidelobe ratio (PSLR) of signals in PC-OTDR. The proposed method introduces an adaptive step factor instead of the traditional fixed factor to reduce the number of iterations. Compared to the traditional method, the proposed method achieves a 2.87 dB improvement of PSLR from a 10 km sensing fiber. In addition, the computation time cost is significantly reduced, which is 1.92 s less than that of the traditional clean algorithm.
The clean algorithm is a popular signal processing technique used to extract point scatterers from a radar image of a target and produce a deconvolved or point-cloud representation. In this paper, a new clean algorith...
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ISBN:
(纸本)9781728153681
The clean algorithm is a popular signal processing technique used to extract point scatterers from a radar image of a target and produce a deconvolved or point-cloud representation. In this paper, a new clean algorithm is proposed using the target's high-resolution range profile. When applied to a 3D temporal interferometric inverse synthetic aperture radar (InISAR) image formation algorithm, considerable improvement is observed when compared to the standard approach. This results in better estimates of the length, width and height of the target, which will improve the accuracy in subsequent target classification.
Digital terrestrial television (DTTV) technology has been developed and used to broadcast the television program. A numerous applications have been developed for the additional feature used with DTTV. One of these fea...
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For synthetic aperture radiometer, radio frequency interference (RFI) seriously contaminates the observed data and affects the quality of the brightness temperature (BT) image. clean algorithm is usually used to mitig...
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For synthetic aperture radiometer, radio frequency interference (RFI) seriously contaminates the observed data and affects the quality of the brightness temperature (BT) image. clean algorithm is usually used to mitigate the Gibbs effect generated by RFI. However, the closely distributed RFI sources cannot be well mitigated by the original clean algorithm. This letter proposes an improved adaptive clean algorithm to enhance the performance of RFI mitigation, especially the closely distributed RFI sources. The loop factor is forced to synchronize with residual BT of RFI for every iteration to avoid over mitigation. Over mitigation can result in a BT vacancy area or an extra BT point generated at the position of RFI. Soil Moisture and Ocean Salinity (SMOS) L1B real data are applied to verify the effectiveness of the improved clean algorithm. The simulation shows that the improved clean algorithm can be competent in eliminating isolated and closely distributed RFIs better than the classic clean algorithm, and the over mitigation problem is solved by the proposed method.
In radio channel measurements and modeling, directional scanning via highly directive antennas is the most popular method to obtain angular channel characteristics to develop and evaluate advanced wireless systems for...
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In radio channel measurements and modeling, directional scanning via highly directive antennas is the most popular method to obtain angular channel characteristics to develop and evaluate advanced wireless systems for high frequency band use. However, it is often insufficient for ray-/cluster-level characterizations because the angular resolution of the measured data is limited by the angular sampling interval over a given scanning angle range and antenna half power beamwidth. This study proposes the sub-grid clean algorithm, a novel technique for high-resolution multipath component (MPC) extraction from the multi-dimensional power image, so called double-directional angular delay power spectrum. This technique can successfully extract the MPCs by using the multi-dimensional power image. Simulation and measurements showed that the proposed technique could extract MPCs for ray-/cluster-level characterizations and channel modeling. Further, applying the proposed method to the data captured at 58 :5 GHz in an atrium entrance hall environment which is an indoor hotspot access scenario in the fifth generation mobile system, the multipath clusters and corresponding scattering processes were identified.
Due to the complexity of oceanic channel, the bearing-time record of weak targets in passive sonar is vague and difficult to observe effectively. In this paper, an algorithm of enhancing multi-Target's Tracks base...
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ISBN:
(纸本)9781538649916
Due to the complexity of oceanic channel, the bearing-time record of weak targets in passive sonar is vague and difficult to observe effectively. In this paper, an algorithm of enhancing multi-Target's Tracks based on Radon transform and clean algorithm is proposed. Radon-clean The algorithm detects the peaks in the Radon transform domain one by one until all the peaks in the image are detected and then the inverse Radon transform is used to obtain an enhanced tracks, so this algorithm has strong noise suppression capability, the algorithm of direct threshold filtering in the Radon transform domain has the defect that if the threshold is chosen to be larger, the weaker target tracks will be filtered out, if the threshold is chosen to be smaller, a large amount of noise will be introduced. Algebraic Radon transform using FFT and matrix operations to overcome the large amount of computational back-projection Radon transform is conducive to real-time implementation of the sonar system. The results of simulation and the sea trial data show that this algorithm can enhance the tracks of multiple weak targets in the low signal-to-noise ratio bearing-time record which has strong interference.
Three-dimensional (3-D) scattering center models use a finite number of point scatterers to efficiently represent complex radar target signature. Using the clean algorithm, 3-D scattering center model is extracted fro...
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Three-dimensional (3-D) scattering center models use a finite number of point scatterers to efficiently represent complex radar target signature. Using the clean algorithm, 3-D scattering center model is extracted from the inverse synthetic aperture radar (ISAR) image, which is generated based on the shooting and bouncing ray (SBR) technique. The conventional clean extracts the strongest peak iteratively based on the assumption that the scattering centers are isolated. In a realistic target, however, both interference from the closely spaced points and additive noise distort the extraction process. This paper proposes a matched filter-based clean algorithm to improve accuracy efficiently. Using the matched filtering of which impulse response is the known point spread function (PSF), a point most correlated with the PSF is extracted. Thus, the proposed method optimally enhances the accuracy in the presence of massive distortions. Numerical simulations using canonical and realistic targets demonstrate that the extraction accuracy is improved without loss of time-efficiency compared with the existing clean algorithms.
A pseudo-random coding side-lobe suppression method based on clean algorithm is *** clean algorithm mainly processes pulse compression results of a pseudo-random coding,and estimates a target＇s distance by a method n...
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A pseudo-random coding side-lobe suppression method based on clean algorithm is *** clean algorithm mainly processes pulse compression results of a pseudo-random coding,and estimates a target＇s distance by a method named interpolation method,so that we can get an ideal pulse compression result of the target,and then use the adjusted ideal pulse compression side-lobe to cut the actual pulse compression result,so as to achieve the remarkable performance of side-lobe suppression for large targets,and let the adjacent small targets *** computer simulations by MATLAB with this method analyze the effect of side-lobe suppression in an ideal or noisy *** is proved that this method can effectively solve the problem due to the side-lobe of pseudo-random coding being too high,and can enhance the radar＇s multi-target detection ability.
The direct wave has a serious impact on the target detection performance of bistatic continuous wave radar system. The conventional direct wave suppression algorithm is LMS algorithm, but it is difficult to be applied...
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ISBN:
(纸本)9781509048281
The direct wave has a serious impact on the target detection performance of bistatic continuous wave radar system. The conventional direct wave suppression algorithm is LMS algorithm, but it is difficult to be applied in Graphic Processing Unit (GPU) due to the large number of iterations. clean algorithm is a direct wave suppression algorithm which is suitable for GPU, whereas the basic clean algorithm cannot adapt to the time-variation of direct wave. In this paper, the basic clean algorithm has been improved to get better performance when the characteristic of direct wave is varied with the time. The correctness and effectiveness of the improved algorithm is verified by the simulation results and testing data analysis.
Aperture synthesis measurements, also termed complex visibilities, are the sparse samplings in the (u, v) frequency plane, which causes undesirable side lobes in the synthesized beam. Through the side lobes, artificia...
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ISBN:
(纸本)9781509033324
Aperture synthesis measurements, also termed complex visibilities, are the sparse samplings in the (u, v) frequency plane, which causes undesirable side lobes in the synthesized beam. Through the side lobes, artificial sources emitting in the protected 1400-1427MHz band are contaminating the retrievals of the soil moisture and ocean salinity (SMOS) satellite launched by the European Space Agency (ESA) in November 2009. An effective way to correct the artificial interferences is to create a synthetic signal as close as possible to the interference and subtract it from the measured data. Based on the same idea, in this paper, we describe an approach to compensate for the effect of interference iteratively, which uses the clean algorithm that was first developed to deconvolve a map made up of some point sources in radio astronomy. It works by finding the brightest point and then removing its contribution iteratively. Experiments based on real SMOS data have been carried out to demonstrate that the proposed algorithm is effective in correcting the influence of RFIs.
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