Journal articles: 'Channel compensation'

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Yang, Ze-min, Meng-dao Xing, Guang-cai Sun, and Zheng Bao. "Joint Multichannel Motion Compensation Method for MIMO SAR 3D Imaging." International Journal of Antennas and Propagation 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/852520.

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The multiple-input-multiple-output (MIMO) synthetic aperture radar (SAR) system with a linear antenna array can obtain 3D resolution. In practice, it suffers from both the translational motion errors and the rotational motion errors. Conventional single-channel motion compensation methods could be used to compensate the motion errors channel by channel. However, this method might not be accurate enough for all the channels. What is more, the single-channel compensation may break the coherence among channels, which would cause defocusing and false targets. In this paper, both the translational motion errors and the rotational motion errors are discussed, and a joint multichannel motion compensation method is proposed for MIMO SAR 3D imaging. It is demonstrated through simulations that the proposed method exceeds the conventional methods in accuracy. And the final MIMO SAR 3D imaging simulation confirms the validity of the proposed algorithm.

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Yan, Jianmin. "Research on Coordination Strategy of Dual Channel Supply Chain for Information and Service Sharing." Frontiers in Business, Economics and Management 6, no. 3 (December 2, 2022): 13–16. http://dx.doi.org/10.54097/fbem.v6i3.3110.

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E-commerce channels are favored by consumers with their low price strategy and cost advantages, while physical retail channels play games in the competition with efficient services. Each has its own advantages, which makes consumers flow between different channels, leading to conflicts between channels. This paper analyzes the dual-channel supply chain cooperation mode of information sharing and service sharing, explores the coordination model based on price compensation strategy, and discusses how the manufacturer's e-commerce channel and retailer's physical channel cooperate through the coordination incentive model based on price compensation strategy to achieve the total profit realized under centralized decision-making, and through service sharing to indirectly redistribute profits, achieving win-win cooperation between both parties.

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ADJEMOV, SERGEY S., EVGENIY M. LOBOV, NIKOLAY A. KANDAUROV, ELIZAVETA O. LOBOVA, and VLADISLAV I. LIPATKIN. "ALGORITHMS OF ESTIMATING AND COMPENSATING THE DISPERSION DISTORTIONS OF WIDEBAND SIGNALS IN THE HF CHANNEL." H&ES Research 13, no. 5 (2021): 57–74. http://dx.doi.org/10.36724/2409-5419-2021-13-5-57-74.

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Introduction: radio communication in the decameter range is actively used for communication in remote and hard-to-reach regions of the world. Decameter communication is also a relevant type of radio communication for regions that have suffered serious damage due to natural disasters. The relevance of using decameter radio communication in the above cases is due to the fact that this technology can offer reliable and cheap solutions. The second area of application of decameter radio communications is communications in the Arctic and Antarctic. Practical significance: when receiving signals with a spread spectrum, it becomes necessary to take into account the effect of the frequency dispersion of the ionospheric channel, since it leads to significant distortions of the useful signal and a decrease in the quality of communication in general. An urgent task is to estimate the parameters of the frequency dispersion of the ionospheric channel and to develop algorithms and devices for compensating dispersion distortions of broadband signals. Discussion: this article presents algorithms for estimating and compensating the dispersion distortions of wideband signals in the HF channel. The subbanding estimation method and maximum likelihood estimation (MLE) of the slope of the dispersion characteristic (the slope of DC) are studied. In addition, this article examines the joint MLE of the slope of DC and other parameters of the wideband signal and offers three methods of dispersion distortion compensation. The first method of compensation is a matched filter compensation. The second one is compensation based on the filter bank. Finally, the third method uses a tracking compensator to solve the problem. The experimental results demonstrated in the article were carried out on a one jump track with a length of about 2900 km.

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Wang, Huan, Qinghua Zeng, Zongyu Zhang, and Hongfu Wang. "Research on Temperature Compensation of Multi-Channel Pressure Scanner Based on an Improved Cuckoo Search Optimizing a BP Neural Network." Micromachines 13, no. 8 (August 19, 2022): 1351. http://dx.doi.org/10.3390/mi13081351.

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A multi-channel pressure scanner is an essential tool for measuring and acquiring various pressure parameters in aerospace applications. It is important to note, however, that the pressure sensor of each of these channels will drift significantly with the increase in the temperature range of the pressure measurement, and the output voltage of each of these channels will show nonlinear characteristics, which will constrain the improvements in the accuracy of the measurement. In the regression fitting process, it is difficult to fit nonlinear data with the traditional least-squares method, which leaves pressure measurement accuracy unsatisfactory. A temperature compensation method based on an improved cuckoo search optimizing a BP neural network for a multi-channel pressure scanner is proposed in this paper to improve pressure measurement accuracy in a wide temperature range. Using the chaotic simplex algorithm, we first improved the cuckoo search algorithm, then optimized the connection weights and thresholds of the BP neural network, and finally constructed an experimental calibration system to investigate the temperature compensation of the multi-channel pressure scanning valves in the −40 °C to 60 °C temperature range. The compensation test results show that the algorithm has a better compensation effect and is more suitable for the temperature compensation of multi-channel pressure scanners than the traditional least-squares method and the standard RBF and BP neural networks. The maximum full-scale error of all 32 channels is 0.02% FS (full-scale error) and below, which realizes its high-accuracy multi-point pressure measurement in a wide temperature range.

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Buscarino, A., L. Fortuna, M. Frasca, G. Sciuto, and Mofeed Rashid. "Compensation of transmission channel effects in chaos synchronization." Iraqi Journal for Electrical and Electronic Engineering 7, no. 1 (June 1, 2011): 83–87. http://dx.doi.org/10.37917/ijeee.7.1.16.

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The synchronization of chaos is a well-known topic which attracted the attention of the scientific community in the last two decades. However, the robustness of the synchronous state has been not widely studied, especially considering real cases in which the effects introduced by the physical channel through which chaotic circuits interact, may deeply influence the quality of synchronization and even the onset of it. In this paper, the synchronization of two chaotic circuit coupled through a non–ideal channel is investigated. In particular, the effects of channels introducing a frequency–independent or frequency–dependent time–delay are investigated. Furthermore, two different design strategies to obtain a linear compensation block able to compensate the considered channel effects are presented and the recovery of the synchronous state is discussed.

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Suryani, Titiek, and Gamantyo Hendrantoro. "Block-Type Pilot Arrangement with Alternating Polarity for ICI Mitigation in Mobile OFDM Systems." Journal of Communications Software and Systems 9, no. 3 (September 23, 2013): 178. http://dx.doi.org/10.24138/jcomss.v9i3.147.

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Improvement on Inter Carrier Interference (ICI)mitigation techniques for OFDM caused by Doppler effectsthrough minimizing channel estimation error and decreasingchannel time varying rate is investigated. The performanceof pilot-aided channel estimation techniques depends on pilot placement and arrangement and also on the channel time varying rate. The block-type and comb-type pilot arrangements are studied through different numbers of guard bands, with or without the involvement of the Doppler shift compensation. The estimation of channel at mid-point of each OFDM symbol is derived from pilot frequencies based on the least square algorithm while the channel interpolation is done using piecewise linear approximation. For ICI mitigation technique we implement frequency domain zero forcing equalizer. We compare the performance of schemes with different pilot arrangementsand Doppler shift compensations by measuring bit error rate with QPSK as sub-channel modulation scheme and with mobileto-fixed of single ring scattering as channel model. The results are in favour of block-type pilot arrangements with alternating polarity and Doppler compensation of 0:55 times the maximum Doppler shift.

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Yastrebov, A. V. "Iterative inversion algorithm for an interference correlation matrix." Journal of «Almaz – Antey» Air and Space Defence Corporation, no. 2 (June 30, 2017): 4–9. http://dx.doi.org/10.38013/2542-0542-2017-2-4-9.

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The article considers efficiency of a multi-channel interference canceller as a function of the number of compensation channels used for a fixed number of jammers. The author suggests an iterative inversion algorithm for an interference correlation matrix, making it possible to achieve zero loss at a certain stage and decrease the computational complexity of determining weight factors for compensation channels

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Malik, Deepak, Geeta Kaushik, and Amit Wason. "Effects of Diverse Dispersion Compensation Formats at Different Data Rates in Light-Wave System." Journal of Optical Communications 40, no. 3 (July 26, 2019): 273–80. http://dx.doi.org/10.1515/joc-2017-0065.

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Abstract In this article, diverse dispersion compensating techniques are demonstrated and also examined their performance in the presence of nonlinearites at different data rates in between 2.5 and 20 Gbps. Dispersion compensation formats such as pre-compensation, post-compensation, hybrid (symmetrical) compensation, Fiber Bragg grating (FBG) and optical phase conjugation (OPC) are used in single-channel light-wave system. The performance is evaluated on the behalf of different parameters such as Q value, Bit error rate (BER) and eye patterns. It is observed that in dispersion compensation, hybrid compensation format gives better results than the other compensation formats. It is also observed that hybrid compensation format is suitable for high data rates up to 20 Gbps while pre- and post-compensation gives better results up to 15 Gbps and FBG and OPC formats covered better results up to 10 Gbps.

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Bogolyubov, V., and L. Bakhtieva. "Compensation Gyrocompass Based on MEMS." Journal of Physics: Conference Series 2096, no. 1 (November 1, 2021): 012203. http://dx.doi.org/10.1088/1742-6596/2096/1/012203.

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Abstract The study of an astatic compensating gyrocompass, built on the basis of a modulation micromechanical gyroscope (MMG) of a hybrid type, has been carried out. A kinematic diagram is given and the principle of operation of the device has describing. The device uses the modulation principle based on obtaining information about the angular motion of the rotor and creating control torques in a rotating coordinate system, which makes it possible to exclude such a significant disadvantage of MMG as "zero offset". A feature of the gyrocompass under consideration is the use of two channels for controlling the rotor of the MMG, namely: a channel for the formation of a guiding moment, striving to combine its main axis with the direction of the true meridian and a channel for compensating this guiding moment. A linearized mathematical model has building, on the base of which an effective algorithm for the operation of a compensatory astatic gyrocompass is proposed. The device under consideration can be used to determine the true azimuth of the longitudinal axis of a mobile ground object, it has a higher measurement speed compared to devices built on three-degree "heavy" gyroscopes, and has good resistance to external influences (vibrations, shocks, etc.).

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Ishii, Ryuta. "Conflict management in dual distribution channel systems: the moderating role of learning capabilities." Journal of Asia Business Studies 14, no. 4 (February 12, 2020): 525–40. http://dx.doi.org/10.1108/jabs-02-2019-0052.

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Purpose In dual distribution channel systems, integrated channels (manufacturer-owned) and independent channels (distributor-owned) are likely to adopt destructive behaviours. To suppress such behaviours, manufacturers need to implement conflict management systems. The purpose of this study is to examine the moderating role of conflict-learning capability (CLC) in the relationship between conflict management system and destructive behaviour. This study also investigates whether interactions between conflict management systems and CLC improve the overall channel performance. Design/methodology/approach Using survey data from 157 Japanese industrial manufacturers, this study conducted regression analyses and mediation analyses. Findings The results show that boundary and compensation systems have different effects on destructive behaviours. On the one hand, compensation systems with strong CLC have a larger impact, although those with weak CLC can also suppress destructive behaviours to some degree. On the other hand, boundary systems with strong CLC suppress destructive behaviours, but those with weak CLC do not. In addition, this study reveals that manufacturers with strong CLC can indirectly improve overall channel performance by implementing conflict management systems and suppressing destructive behaviours. Originality/value Previous studies reveal that boundary and compensation systems suppress destructive behaviours. However, these studies neglect the importance of organisational capability in the successful implementation of conflict management systems. By focusing on CLC, this study advances our understanding of dual distribution and channel conflict.

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Alsevska, A., V. Dilendorfs, S. Spolitis, and Vj Bobrovs. "Comparison of Chromatic Dispersion Compensation Method Efficiency for 10 Gbit/S RZ-OOK and NRZ-OOK Wdm-Pon Transmission Systems." Latvian Journal of Physics and Technical Sciences 54, no. 6 (December 1, 2017): 65–75. http://dx.doi.org/10.1515/lpts-2017-0042.

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Abstract In the paper, the authors compare efficiency of two physical dispersion compensation methods for single channel and 8-channel WDM fibre-optical transmission systems using return-to-zero (RZ) and non-return-to-zero (NRZ) line codes for operation within optical C-band frequencies by means of computer simulations. As one of the most important destructive effects in fibre optical transmission systems (FOTS) is chromatic dispersion (CD), it is very important to reduce its negative effect on a transmitted signal. Dispersion compensation methods that were implemented in the research were dispersion compensating fibre (DCF) and fibre Bragg grating (FBG). The main goal of the paper was to find out which dispersion compensation method (DCF or FBG) provided the highest performance increase for fibre-optical transmission system and provided the longest transmission distance after dispersion compensation was implemented at different locations in the fibre-optical line while RZ or NRZ line codes were used. In the paper the reference point of signal quality for all measurements, which were obtained at the receiver, was BER<10−12.

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He, Fei, Andrew Harms, and Lamar Yaoqing Yang. "Tensor Rank Regularization with Bias Compensation for Millimeter Wave Channel Estimation." Signals 3, no. 4 (September 24, 2022): 664–81. http://dx.doi.org/10.3390/signals3040040.

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This paper presents a novel method of tensor rank regularization with bias compensation for channel estimation in a hybrid millimeter wave MIMO-OFDM system. Channel estimation is challenging due to the unknown number of multipath components that determines the channel rank. In general, finding the intrinsic rank of a tensor is a non-deterministic polynomial-time (NP) hard problem. However, by leveraging the sparse characteristics of millimeter wave channels, we propose a modified CANDECOMP/PARAFAC (CP) decomposition-based method that jointly estimates the tensor rank and channel component matrices. Our approach differs from most existing works that assume the number of channel paths is known and the proposed method is able to estimate channel parameters accurately without the prior knowledge of number of multipaths. The objective of this work is to estimate the tensor rank by a novel sparsity-promoting prior that is incorporated into a standard alternating least squares (ALS) function. We introduce a weighting parameter to control the impact of the previous estimate and the tensor rank estimation bias compensation in the regularized ALS. The channel information is then extracted from the estimated component matrices. Simulation results show that the proposed scheme outperforms the baseline l1 strategy in terms of accuracy and robustness. It also shows that this method significantly improves rank estimation success at the expense of slightly more iterations.

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Ye, Yuan, Ling Fu, Zhang Junhua, Wei Wang, Liu Yanbin, and Bin Wu. "Research on Precise Flow Control and Anti-interference Performance of Load Sensitive Multi-way Valve with After-valve Compensation." Journal of Physics: Conference Series 2419, no. 1 (January 1, 2023): 012065. http://dx.doi.org/10.1088/1742-6596/2419/1/012065.

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Abstract Regarding a load-sensitive system with after-valve compensation, in the case of a single action or composite action, theoretically, the flow of each channel neither varies with the load pressure of this channel, nor is it affected by the flow of other channels, and the anti-interference performance is good. In fact, due to the influence of factors such as the flow passage of the valve body, the matching between the pressure compensation valve and the main spool, its flow control and anti-interference performance are difficult to achieve good results, which has a great impact on the synchronization, rapid action impact and micro motion characteristics of the main engine of construction machinery. This paper studies the simplification and analysis of the system pressure drop diagram, the matching characteristics between the pressure compensation valve and the main valve, accurate modeling and simulation technology, solves the problems of flow fine control and anti-interference performance, improves the flow control accuracy of a single action and compound action, and enhances the anti-interference performance. The real vehicle test shows that the self-developed multi-way valve for compensating for load sensitivity behind the valve is installed on the 6T small excavation. The initial position of the excavator’s track is aligned along a straight line. After the test runs for 20 meters, the track offset is measured. The fast forward offset is only 20mm, and the slow forward offset is only 7mm.

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Zhang, Xuelong, Hui Wang, Xiangzhong Zhao, and Doudou Wu. "Return Decision Model of the Manufacturer-Leading Dual-Channel Supply Chain." Mathematical Problems in Engineering 2020 (November 30, 2020): 1–15. http://dx.doi.org/10.1155/2020/8864672.

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According to the manufacturer-leading dual-channel supply chain return problem, a linear demand function considering the change rate of product interaction between the two channels and the change rate of market demand on the return price was established. Under the premise of no cross-return, this paper analyzes the changes of the optimal profit value of the manufacturer, retailer, and supply chain of the dual-channel supply chain in the context of centralized and decentralized decision-making and through the establishment of the price discount decision model and compensation strategy to coordinate the whole supply chain profit. This paper has shown that the use of the price discount decision model and compensation policy model could make the whole supply chain profit optimum value in decentralized decision-making situations equal to profit optimum value in the centralized decision-making situations, and price discount model could make manufacturers better to maximize profit considering the same return scenario, and that compensation policy model could be more helpful to maximize profits for retailers.

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Kim, Eugene Z., Julie Vienne, Michael Rosbash, and Leslie C. Griffith. "Nonreciprocal homeostatic compensation in Drosophila potassium channel mutants." Journal of Neurophysiology 117, no. 6 (June 1, 2017): 2125–36. http://dx.doi.org/10.1152/jn.00002.2017.

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Homeostatic control of intrinsic excitability is important for long-term regulation of neuronal activity. In conjunction with many other forms of plasticity, intrinsic homeostasis helps neurons maintain stable activity regimes in the face of external input variability and destabilizing genetic mutations. In this study, we report a mechanism by which Drosophila melanogaster larval motor neurons stabilize hyperactivity induced by the loss of the delayed rectifying K+ channel Shaker cognate B ( Shab), by upregulating the Ca2+-dependent K+ channel encoded by the slowpoke ( slo) gene. We also show that loss of SLO does not trigger a reciprocal compensatory upregulation of SHAB, implying that homeostatic signaling pathways utilize compensatory pathways unique to the channel that was mutated. SLO upregulation due to loss of SHAB involves nuclear Ca2+ signaling and dCREB, suggesting that the slo homeostatic response is transcriptionally mediated. Examination of the changes in gene expression induced by these mutations suggests that there is not a generic transcriptional response to increased excitability in motor neurons, but that homeostatic compensations are influenced by the identity of the lost conductance. NEW & NOTEWORTHY The idea that activity-dependent homeostatic plasticity is driven solely by firing has wide credence. In this report we show that homeostatic compensation after loss of an ion channel conductance is tailored to identity of the channel lost, not its properties.

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Ye, Peng, Huiqing Pan, Hao Zeng, Min Li, and Wuhuang Huang. "A Self-Adaptive Frequency Response Compensation Method for a TIADC System." Mathematical Problems in Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/613025.

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Time interleaving is one of the most efficient techniques employed in high-speed sampling systems. However, the frequency response mismatch among different channels will create distortion tones that degrade the system performance. In this paper, a self-adaptive frequency response mismatch compensation method is presented, where the design of compensation filter is optimized with a self-adapting strategy. This digital postprocessing technique realizes the compensation of frequency response effectively and also the increase of the digital bandwidth of the acquisition system. MATLAB-based simulation and an actual two-channel acquisition system test verify the effectiveness of the algorithm.

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Yang, Ling, Fubo Zhang, Yihong Sun, Longyong Chen, Zhenhua Li, and Dawei Wang. "Motion Error Estimation and Compensation of Airborne Array Flexible SAR Based on Multi-Channel Interferometric Phase." Remote Sensing 15, no. 3 (January 23, 2023): 680. http://dx.doi.org/10.3390/rs15030680.

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Airborne array synthetic aperture radar (SAR) has made a significant breakthrough in the three-dimensional resolution of traditional SAR. In the airborne array SAR 3D imaging technology, the baseline length is the main factor restricting the resolution. Airborne array flexible SAR can increase the baseline length to improve the resolution and interference performance by mounting antennae on the wing. The existing research lacks results obtained using flexible actual data processing and specific motion compensation methods. Thus, this paper proposes a motion error estimation and compensation method for an airborne array flexible SAR based on a multi-channel interferometric phase. Firstly, a flexible channel motion compensation model is established based on the multi-channel interference phase of airborne array flexible SAR. Then, based on the rigid multi-channel data, combined with the ground control points, the least square method, and the global optimal search algorithm, the accurate rigid baseline length and the central incidence angle are obtained. Finally, according to the multi-channel interference phase inversion of the flexible motion error and combined with the motion compensation model, the flexible data are compensated in the time domain. The actual results indicate that, compared with traditional motion compensation methods, our method can obtain accurate flexible compensation data. This study improves the interference performance of multi-channel data of airborne array flexible SAR and lays a solid foundation for the high-precision 3D reconstruction of airborne array flexible SAR.

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Murti, Wisnu, and Ji-Hoon Yun. "Multilink Operation in IEEE 802.11be Wireless LANs: Backoff Overflow Problem and Solutions." Sensors 22, no. 9 (May 4, 2022): 3501. http://dx.doi.org/10.3390/s22093501.

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The next-generation wireless LAN standard named IEEE 802.11be supports a multilink operation to cost-efficiently boost throughput performance, for which an efficient multilink channel scheme is essential. The synchronous channel access scheme with an enhancement allowing multilink transmission before backoff completion greatly enhances the performance of multilink devices with no simultaneous transmit and receive capability, for which, however, backoff count compensation is necessary for coexistence with legacy and other multilink devices. In this paper, we identify the backoff count overflow problem of the enhanced synchronous channel access scheme with backoff compensation, which becomes aggravated once triggered due to repeated compensations. Then, we propose four solutions to mitigate this problem: limiting consecutive free-riding transmissions, limiting a compensated backoff value, using the contention window value of a main link, and balancing transmissions between links. Through comparative evaluation and analyses for dense single-spot and indoor random deployment scenarios, we demonstrate in terms of throughput and latency that the proposed solutions successfully mitigate the problem while preserving the coexistence performance.

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Korablyov, Yuri Anatolievich. "INTELLIGENT CONTROL OF FAULT COMPENSATION CHANNEL REDUNDANCY." Sovremennaya nauka i innovatsii, no. 4 (2020): 10–17. http://dx.doi.org/10.37493/2307-910x.2020.4.1.

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Omura, Takaki, Shun Kojima, Kazuki Maruta, and Chang-Jun Ahn. "Neural network based channel identification and compensation." IEICE Communications Express 8, no. 10 (2019): 416–21. http://dx.doi.org/10.1587/comex.2019xbl0095.

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Zhang, Lei, Yunkai Deng, and Robert Wang. "Channel Phase Error Compensation for MIMO-SAR." International Journal of Antennas and Propagation 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/798673.

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Multi-input multioutput (MIMO) is a novel technique to achieve high-resolution as well as wide swath in synthetic aperture radar (SAR) systems. Channel imbalance is inevitable in multichannel systems that it declines the imaging quality. Generally, the imbalance cannot be fully compensated by simple internal calibration in a MIMO-SAR system. In this paper, a new algorithm based on raw data is presented to remove the channel phase error. Based on the error source, this approach models the phase error as two parts: the transmit phase error and the receive phase error. The receive phase error is removed using cost function at the azimuth processing stage, whereas the transmit phase error is estimated with correlation. Point target simulations confirm the influence of channel phase error and the validation of the proposed approach. Besides, the performance is also investigated.

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Moreno, Daniel, Julio Rufo, Victor Guerra, Jose Rabadan, and Rafael Perez-Jimenez. "Effect of Temperature on Channel Compensation in Optical Camera Communication." Electronics 10, no. 3 (January 22, 2021): 262. http://dx.doi.org/10.3390/electronics10030262.

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General-purpose Complementary Metal Oxide Semiconductor (CMOS) sensors perform the image desegregation in three channels (red, green, and blue) as a result of a band-pass wavelength filtering carried out using Foveon or Bayer filters. This characteristic can be used in Optical Camera Communication (OCC) systems for increasing the links’ data rate by introducing Wavelength Division Multiplexing (WDM) or Color Shift Keying (CSK) modulation schemes. However, these techniques need a compensation stage to mitigate the cross-talk between channels introduced by the filters. This compensation is performed by a Channel State Information (CSI) estimation and a zero-forcing compensation scheme. The impact of the temperature effects of light-emitting diode (LED) emissions on the zero-forcing compensation scheme’s performance has not been analyzed in depth. This work presents a comprehensive methodology and experimental characterization of this impact for Foveon and Bayer-based image sensors, assuming that the CSI is estimated under temperature conditions different from the LED’s stationary temperature regime. Besides, Signal-to-Interference-plus-Noise Ratio (SINR) and Bit Error Rate (BER) performance metrics are presented in order to estimate the repercussion in an OCC link. The results reveal that the Foveon sensor obtains more unsatisfactory performance than the Bayer-based sensor. On the other hand, the blue band is the most penalized by the thermal effect.

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Zhou, Liming, Xiaoling Zhang, Liming Pu, Tianwen Zhang, Jun Shi, and Shunjun Wei. "A High-Precision Motion Errors Compensation Method Based on Sub-Image Reconstruction for HRWS SAR Imaging." Remote Sensing 14, no. 4 (February 21, 2022): 1033. http://dx.doi.org/10.3390/rs14041033.

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High-resolution wide-swath (HRWS) synthetic aperture radar (SAR) plays an important role in remote sensing observation. However, the motion errors caused by the carrier platform’s instability severely degrade the performance of the HRWS SAR imaging. Conventional motion errors compensation methods have two drawbacks, i.e., (1) ignoring the spatial variation of the phase errors of pixels along the range direction of the scene, which leads to lower compensation accuracy, and (2) performing compensation after echo reconstruction, which fails to consider the difference in motion errors between channels, resulting in poor imaging performance in the azimuth direction. In this paper, to overcome these two drawbacks, a high-precision motion errors compensation method based on sub-image reconstruction (SI-MEC) for high-precision HRWS SAR imaging is proposed. The proposed method consists of three steps. Firstly, the motion errors of the platform are estimated by maximizing the intensity of strong points in multiple regions. Secondly, combined with the multichannel geometry, the equivalent phase centers (EPCs) used for sub-images imaging are corrected and the sub-images imaging is performed before reconstruction. Thirdly, the reconstruction is performed by using the sub-images. The proposed method has two advantages, i.e., (1) compensating for the spatially varying phase errors in the range direction, by correcting EPCs, to improve the imaging quality, and (2) compensating for the motion errors of each channel in sub-image imaging before reconstruction, to enhance the imaging quality in the azimuth direction. Moreover, the experimental results are provided to demonstrate that the proposed method outperforms PGA and BP-FMSA.

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Makarau, Aliaksei, Rudolf Richter, Viktoria Zekoll, and Peter Reinartz. "CIRRUS REMOVAL IN MULTISPECTRAL DATAWITHOUT 1.38μM SPECTRAL DATA." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-7 (June 7, 2016): 41–44. http://dx.doi.org/10.5194/isprsannals-iii-7-41-2016.

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Cirrus is one of the most common artifacts in the remotely sensed optical data. Contrary to the low altitude (1-3 km) cloud the cirrus cloud (8-20 km) is semitransparent and the extinction (cirrus influence) of the upward reflected solar radiance can be compensated. The widely employed and almost ’de-facto’ method for cirrus compensation is based on the 1.38μm spectral channel measuring the upwelling radiance reflected by the cirrus cloud. The knowledge on the cirrus spatial distribution allows to estimate the per spectral channel cirrus attenuation and to compensate the spectral channels. A wide range of existing and expected sensors have no 1.38μm spectral channel. These sensors data can be corrected by the recently developed haze/cirrus removal method. The additive model of the estimated cirrus thickness map (CTM) is applicable for cirrus-conditioned extinction compensation. Numeric and statistic evaluation of the CTM-based cirrus removal on more than 80 Landsat-8 OLI and 30 Sentinel-2 scenes demonstrates a close agreement with the 1.38μm channel based cirrus removal.

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Makarau, Aliaksei, Rudolf Richter, Viktoria Zekoll, and Peter Reinartz. "CIRRUS REMOVAL IN MULTISPECTRAL DATAWITHOUT 1.38μM SPECTRAL DATA." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-7 (June 7, 2016): 41–44. http://dx.doi.org/10.5194/isprs-annals-iii-7-41-2016.

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Cirrus is one of the most common artifacts in the remotely sensed optical data. Contrary to the low altitude (1-3 km) cloud the cirrus cloud (8-20 km) is semitransparent and the extinction (cirrus influence) of the upward reflected solar radiance can be compensated. The widely employed and almost ’de-facto’ method for cirrus compensation is based on the 1.38μm spectral channel measuring the upwelling radiance reflected by the cirrus cloud. The knowledge on the cirrus spatial distribution allows to estimate the per spectral channel cirrus attenuation and to compensate the spectral channels. A wide range of existing and expected sensors have no 1.38μm spectral channel. These sensors data can be corrected by the recently developed haze/cirrus removal method. The additive model of the estimated cirrus thickness map (CTM) is applicable for cirrus-conditioned extinction compensation. Numeric and statistic evaluation of the CTM-based cirrus removal on more than 80 Landsat-8 OLI and 30 Sentinel-2 scenes demonstrates a close agreement with the 1.38μm channel based cirrus removal.

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Basova, O. A., S. A. Gladilin, A. S. Grigoryev, and D. P. Nikolaev. "Two calibration models for compensation of the individual elements properties of self-emitting displays." Computer Optics 46, no. 2 (April 2022): 335–44. http://dx.doi.org/10.18287/2412-6179-co-854.

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In this paper, we examine the applicability limits of different methods of compensation of the individual properties of self-emitting displays with significant non-uniformity of chromaticity and maximum brightness. The aim of the compensation is to minimize the perceived image non-uniformity. Compensation of the displayed image non-uniformity is based on minimizing the perceived distance between the target (ideally displayed) and the simulated image displayed by the calibrated screen. The S-CIELAB model of the human visual system properties is used to estimate the perceived distance between two images. In this work, we compare the efficiency of the channel-wise and linear (with channel mixing) compensation models depending on the models of variation in the characteristics of display elements (subpixels). It was found that even for a display with uniform chromatic subpixels characteristics, the linear model with channel mixing is superior in terms of compensation accuracy.

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Basova, O. A., S. A. Gladilin, A. S. Grigoryev, and D. P. Nikolaev. "Two calibration models for compensation of the individual elements properties of self-emitting displays." Computer Optics 46, no. 2 (April 2022): 335–44. http://dx.doi.org/10.18287/2412-6179-co-854.

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In this paper, we examine the applicability limits of different methods of compensation of the individual properties of self-emitting displays with significant non-uniformity of chromaticity and maximum brightness. The aim of the compensation is to minimize the perceived image non-uniformity. Compensation of the displayed image non-uniformity is based on minimizing the perceived distance between the target (ideally displayed) and the simulated image displayed by the calibrated screen. The S-CIELAB model of the human visual system properties is used to estimate the perceived distance between two images. In this work, we compare the efficiency of the channel-wise and linear (with channel mixing) compensation models depending on the models of variation in the characteristics of display elements (subpixels). It was found that even for a display with uniform chromatic subpixels characteristics, the linear model with channel mixing is superior in terms of compensation accuracy.

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Sakaue, Taichi, Chang-Jun Ahn, Tatsuya Omori, and Ken-Ya Hashimoto. "Time Domain Replica Signal Based Interference Compensation for SP-MIMO/OFDM with Large Delay Spread Channel." International Journal of Distributed Systems and Technologies 5, no. 4 (October 2014): 1–17. http://dx.doi.org/10.4018/ijdst.2014100101.

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In mobile communications, MIMO-OFDM transmission performance suffers severe degradation caused by the large delay spread channel greater than guard interval (GI). This is because the excess delay results in considerable inter-symbol interference (ISI) between adjacent symbols and inter-carrier-interference (ICI) among subcarrier in the same symbol. In case of scattered pilot (SP), the interference of pilot signals causes the deterioration of channel estimation. To mitigate this problem, in this paper, we propose the interference compensation scheme using the time domain replica signals. We make the time domain replica signals from detected signals and the excess channel impulse responses over GI. After compensation of the time domain replica signals and the received signals, we recalculate the channel state information (CSI) and the CSI is updated. Finally, we carry out the channel compensation with updated CSI for obtaining accurate compensated signals.

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Lee, Ho Sang. "Efficient Sandstorm Image Enhancement Using the Normalized Eigenvalue and Adaptive Dark Channel Prior." Technologies 9, no. 4 (December 17, 2021): 101. http://dx.doi.org/10.3390/technologies9040101.

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A sandstorm image has features similar to those of a hazy image with regard to the obtaining process. However, the difference between a sand dust image and a hazy image is the color channel balance. In general, a hazy image has no color cast and has a balanced color channel with fog and dust. However, a sand dust image has a yellowish or reddish color cast due to sand particles, which cause the color channels to degrade. When the sand dust image is enhanced without color channel compensation, the improved image also has a new color cast. Therefore, to enhance the sandstorm image naturally without a color cast, the color channel compensation step is needed. Thus, to balance the degraded color channel, this paper proposes the color balance method using each color channel’s eigenvalue. The eigenvalue reflects the image’s features. The degraded image and the undegraded image have different eigenvalues on each color channel. Therefore, if using the eigenvalue of each color channel, the degraded image can be improved naturally and balanced. Due to the color-balanced image having the same features as the hazy image, this work, to improve the hazy image, uses dehazing methods such as the dark channel prior (DCP) method. However, because the ordinary DCP method has weak points, this work proposes a compensated dark channel prior and names it the adaptive DCP (ADCP) method. The proposed method is objectively and subjectively superior to existing methods when applied to various images.

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Lv, Gang, and Heming Zhao. "Joint Factor Analysis of Channel Mismatch in Whispering Speaker Verification." Archives of Acoustics 37, no. 4 (December 1, 2012): 555–59. http://dx.doi.org/10.2478/v10168-012-0065-9.

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Abstract A speaker recognition system based on joint factor analysis (JFA) is proposed to improve whispering speakers’ recognition rate under channel mismatch. The system estimated separately the eigenvoice and the eigenchannel before calculating the corresponding speaker and the channel factors. Finally, a channel-free speaker model was built to describe accurately a speaker using model compensation. The test results from the whispered speech databases obtained under eight different channels showed that the correct recognition rate of a recognition system based on JFA was higher than that of the Gaussian Mixture Model-Universal Background Model. In particular, the recognition rate in cellphone channel tests increased significantly.

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K. Khairi, K. Khairi, H. Fong Kok H. Fong Kok, Z. Lambak Z. Lambak, M. I. Abdan M. I. Abdan, M. A. Farhan M. A. Farhan, M. H. Othman M. H. Othman, M. L. H. Jamaluddin M. L. H. Jamaluddin, et al. "Investigation on the pre-compensation and post-?compensation cascaded multi-channel-chirped fiber Bragg gratings for a repeaterless transmission system." Chinese Optics Letters 16, no. 4 (2018): 040607. http://dx.doi.org/10.3788/col201816.040607.

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Wang, Shuai, Maosheng Xiang, Bingnan Wang, Fubo Zhang, and Yirong Wu. "A channel phase error compensation method for multi-channel synthetic aperture ladar." Optik 178 (February 2019): 830–40. http://dx.doi.org/10.1016/j.ijleo.2018.10.074.

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Wang, Taotao, and Soung Chang Liew. "Frequency-Asynchronous Multiuser Joint Channel-Parameter Estimation, CFO Compensation, and Channel Decoding." IEEE Transactions on Vehicular Technology 65, no. 12 (December 2016): 9732–46. http://dx.doi.org/10.1109/tvt.2016.2524206.

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Xu, Tongyang, Hedaia Ghannam, and Izzat Darwazeh. "Practical Evaluations of SEFDM: Timing Offset and Multipath Impairments." Infocommunications journal, no. 4 (2018): 2–9. http://dx.doi.org/10.36244/icj.2018.4.1.

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The non-orthogonal signal waveform spectrally efficient frequency division multiplexing (SEFDM) improves spectral efficiency at the cost of self-created inter carrier interference (ICI). As the orthogonal property, similar to orthogonal frequency division multiplexing (OFDM), no longer exists, the robustness of SEFDM in realistic wireless environments might be weakened. This work aims to evaluate the sensitivity of SEFDM to practical channel distortions using a professional experiment testbed. First, timing offset is studied in a bypass channel to locate the imperfection of the testbed and its impact on SEFDM signals. Then, the joint effect of a multipath frequency selective channel and additive white Gaussian noise (AWGN) is investigated in the testbed. Through practical experiments, we demonstrate the performance of SEFDM in realistic radio frequency (RF) environments and verify two compensation methods for SEFDM. Our results show first frequency-domain compensation works well in frequency non-selective channel conditions while time-domain compensation method is suitable for frequency selective channel conditions. This work paves the way for the application of SEFDM in different channel scenarios.

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Elagina, K. A. "Compensation of target signal migration in the multichannel matched filter." Journal of «Almaz – Antey» Air and Space Defence Corporation, no. 3 (October 24, 2021): 69–78. http://dx.doi.org/10.38013/2542-0542-2021-3-69-78.

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The study proposes a method of target range signal compensation within different pulse burst periods during in-period matched filtering. The proposed method allows to reduce losses in case of long-term signal integration. This is especially important for signals highly sensitive to Doppler frequency shift. In terms of this parameter, a multichannel configuration of the compression filter is a probable solution for such signals. Based on the example of a signal with non-linear frequency modulation and the results of simulation modelling, we analyse the effectiveness of migration compensation and give recommendations on channel multiplexing for the compression filter with an integrated migration compensator.

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Zhao, Yiru, Chaoquan Wang, Zeping Zhao, Weijie Zhang, and Jianguo Liu. "A Microwave Photonics True-Time-Delay System Using Carrier Compensation Technique Based on Wavelength Division Multiplexing." Photonics 10, no. 1 (December 28, 2022): 34. http://dx.doi.org/10.3390/photonics10010034.

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A novel microwave photonic true-time-delay (TTD) system using carrier compensation technology is proposed and experimentally demonstrated. Wavelength division multiplexing combines ten lasers into a single beam. We separate one channel from the laser as a compensating carrier, and the compensation carrier is combined with the time-delayed optical signals to be detected. Meanwhile, sideband signals are amplified effectively thanks to carrier-suppressed double-sideband (CS-DSB) modulation. Therefore, the power of both the central optical carriers and sidebands is guaranteed, which produces a better beat frequency result than the TTD system without carrier compensation. The simulation results confirm that the signal amplitude has an order of magnitude improvement due to the compensation. With employing the delay fibers based on multiple-fiber Bragg gratings (MFBGs), the experimental delay and response time reach 90.160 μs and 160.80 ns. The proposed technique can find applications in time-delay beamforming of phased array antennas (PAAs).

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Han, Jiqing, and Wen Gao. "Robust telephone speech recognition based on channel compensation." Pattern Recognition 32, no. 6 (June 1999): 1061–67. http://dx.doi.org/10.1016/s0031-3203(98)00113-7.

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Wei, Haiqing, and David V. Plant. "Intra-channel nonlinearity compensation with scaled translational symmetry." Optics Express 12, no. 18 (2004): 4282. http://dx.doi.org/10.1364/opex.12.004282.

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Ramachandran, Ravi P., and Peter Kabal. "Transmultiplexers: Perfect reconstruction and compensation of channel distortion." Signal Processing 21, no. 3 (November 1990): 261–74. http://dx.doi.org/10.1016/0165-1684(90)90091-c.

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Sutardja, P. "A post-compensation scheme for peak-detect channel." IEEE Transactions on Magnetics 26, no. 5 (1990): 2303–5. http://dx.doi.org/10.1109/20.104704.

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T. Rashid, M., G. Sciuto, M. Frasca, L. Fortuna, and A. Buscarino. "Compensation of transmission channel effects in chaos synchronization." Iraqi Journal for Electrical And Electronic Engineering 7, no. 1 (June 28, 2011): 83–87. http://dx.doi.org/10.33762/eeej.2011.42051.

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Li, Bing, and Bin-Jie Hu. "Imaging Method Based on Time Reversal Channel Compensation." International Journal of Antennas and Propagation 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/894608.

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The conventional time reversal imaging (TRI) method builds imaging function by using the maximal value of signal amplitude. In this circumstance, some remote targets are missed (near-far problem) or low resolution is obtained in lossy and/or dispersive media, and too many transceivers are employed to locate targets, which increases the complexity and cost of system. To solve these problems, a novel TRI algorithm is presented in this paper. In order to achieve a high resolution, the signal amplitude corresponding to focal time observed at target position is used to reconstruct the target image. For disposing near-far problem and suppressing spurious images, combining with cross-correlation property and amplitude compensation, channel compensation function (CCF) is introduced. Moreover, the complexity and cost of system are reduced by employing only five transceivers to detect four targets whose number is close to that of transceivers. For the sake of demonstrating the practicability of the proposed analytical framework, the numerical experiments are actualized in both nondispersive-lossless (NDL) media and dispersive-conductive (DPC) media. Results show that the performance of the proposed method is superior to that of conventional TRI algorithm even under few echo signals.

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Shabaan, Omar Y., and Omar A. Athab. "Hybrid compensation of polarization-multiplexed QPSK optical format for high bit rate networks." Indonesian Journal of Electrical Engineering and Computer Science 20, no. 3 (December 1, 2020): 1325. http://dx.doi.org/10.11591/ijeecs.v20.i3.pp1325-1331.

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<span lang="EN-GB">Transmitting the highest capacity throughput over the longest possible distance without any regeneration stage is an important goal of any long-haul optical network system. Accordingly, Polarization-Multiplexed Quadrature Phase-Shift-Keying (PM-QPSK) was introduced lately to achieve high bit-rate with relatively high spectral efficiency. Unfortunately, the required broad bandwidth of PM-QPSK increases the linear and nonlinear impairments in the physical layer of the optical fiber network. Increased attention has been spent to compensate for these impairments in the last years. In this paper, Single Mode Fiber (SMF), single channel, PM-QPSK transceiver was simulated, with a mix of optical and electrical (Digital Signal Processing (DSP)) compensation stages to minimize the impairments. The behaviour of the proposed system was investigated under four conditions: without compensation, with only optical compensator, with only DSP compensator and finally with both compensators. An evidence improvement was noticed in the case of hybrid compensation, where the transmission distance was multiplied from (720 km) to more than (3000 km) at 40 Gb/s.</span>

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Sun, Zong Xin, Wei Wang, Yue Wang, Rehan Khan, and Gang Qiao. "Pilots Updating Channel Compensation Base on Underwater MIMO-OFDM." Applied Mechanics and Materials 198-199 (September 2012): 1761–67. http://dx.doi.org/10.4028/www.scientific.net/amm.198-199.1761.

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The communication rate is limited extremely by the confined bandwidth source of UWA (underwater acoustic) channel. MIMO (Multiple-input Multiple-output) techniques can drastically improve the spectral efficiency, and have been a new hot spot in UWA commutation. To estimate the UWA channel STBC (space-time block code) technique is adopted, and the improved method of channel estimating is also given. A designed of complex coding MIMO-OFDM is provided.The validity and the dependability of the scheme are verified by Monte Carlo simulations.

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Partap, Bhanu, Prabhjot Singh, and . "Hybrid Approach for Channel Estimation Using Iterative Compensation and LMS Algorithm." International Journal of Engineering & Technology 7, no. 3.8 (July 7, 2018): 34. http://dx.doi.org/10.14419/ijet.v7i3.8.15214.

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In Orthogonal Frequency Division Multiplexing, the concept of channel equalization and estimation plays a vital role to improve the performance of the system by reducing the effects of distortion in the signals that occurs due to fading, multipath, delay spreads. In this study a hybrid channel estimation technique is developed by collaborating the iterative compensation mechanism with Least Mean Square technique. The performance of the proposed work is observed to be more effective and efficient than the Iterative compensation based channel estimation technique in the terms of Mean Square Error (MSE).

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Yang, Jiaquan, Xumei Zhang, Yating Huang, Jiafu Su, Sang-Bing Tsai, Li-Chung Chang, and Jiangtao Wang. "Capacity Allocation and Compensation in a Dual-Channel Supply Chain under Uncertain Environment." Mathematical Problems in Engineering 2019 (August 26, 2019): 1–12. http://dx.doi.org/10.1155/2019/3154734.

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The dual-channel supply chain is widely adopted by main manufacturers, potentially incurring channel conflicts between the traditional retail channel which is owned by the independent retailer and the online channel which is directly managed by the manufacturer. The purpose of this paper is to deal with the scenario where channel conflicts may arise under production capacity uncertainty, when the manufacturer tends to privilege the direct selling channel over the retail selling channel. To achieve the goal, this paper establishes a Stackelberg game model consisting of a manufacturer and a retailer, studies the scenario where the manufacturer satisfies the direct selling channel first in the presence of capacity uncertainty, employs the decision optimization and the backward induction method to find the optimal inventory decision in the direct selling channel and the optimal order quantity decision making in the retail selling channel, and designs a compensation mechanism aiming to coordinate the channel conflict in the decentralized decision-making process. Results show that the optimal decisions aiming to maximize the expected profit of each supply chain member are not able to maximize the expected profit of entire dual-channel supply chain. However, when the manufacturer compensates the retailer’s profit loss based on the unsatisfied order and, in the meantime, adjusts the wholesale price to prevent the retailer which obtains the compensation from increasing order significantly, the compensation mechanism can coordinate the decision of each supply chain member, mitigate the channel conflict, maximize the expected profit of entire dual-channel supply chain, and achieve the Pareto improvement of supply chain members’ expected profit in the decentralized decision-making process.

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Sun, Guangcai, Jixiang Xiang, Mengdao Xing, Jun Yang, and Liang Guo. "A Channel Phase Error Correction Method Based on Joint Quality Function of GF-3 SAR Dual-Channel Images." Sensors 18, no. 9 (September 17, 2018): 3131. http://dx.doi.org/10.3390/s18093131.

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Multichannel SAR is an effective approach to solving the contradiction between high azimuth resolution and wide swath. The goal of this paper is to obtain a new and effective method for estimating and compensating the interchannel phase error of the Chinese GF-3 Synthetic aperture radar (SAR). A channel phase error correction method based on the optimal value of the image domain quality function is proposed. In this method, the phase error is initially compensated using the correlation function method. In the fine correction of dual-channel phase error, a heuristic search algorithm is used to estimate the residual phase by searching the extremum of the quality function. After phase compensation in the image domain, the azimuth ambiguities caused by the remaining phase are eliminated. The proposed image domain processing method provides a new idea for channel phase error correction. The measured data of high-resolution GF-3 dual-channel ultrafine imaging mode verifies the validity of this method.

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Liu, Wei. "Coordination and Compensation Model of E-Commerce Dual-Channel Supply Chain Based on Optimized Genetic Algorithm." International Journal of Circuits, Systems and Signal Processing 16 (January 13, 2022): 426–32. http://dx.doi.org/10.46300/9106.2022.16.52.

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Due to the conflict between traditional channels and electronic channels in the e-commerce dual-channel supply chain, retailers are threatened and need to be compensated in some way. Based on this, an e-commerce dual-channel supply chain coordination compensation model based on optimized genetic algorithm is designed. Based on the problem description and basic assumptions, analyze the manufacturer’s profit and the retailer’s maximum profit in the case of centralized decision-making and decentralized decision-making. The genetic algorithm is optimized by introducing a collaborative genetic operator, and the optimized genetic algorithm is used to obtain dual e-commerce channels. The maximum profit of the supply chain, so far, the model design is completed. Through comparative experiments, the optimized genetic algorithm used in the model is compared with two traditional algorithms. Experimental results show that the proposed algorithm takes shorter iteration time to solve the problem, its convergence is better, and it can effectively obtain a global optimal solution instead of a local optimal solution.

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Wang, Yuan, Zhou Mo Zeng, Yi Bo Li, Wen Zhang, and Hao Feng. "Research on Doppler and Channel Estimation for Multicarrier Spread Spectrum Underwater Acoustic Communication System." Advanced Materials Research 1079-1080 (December 2014): 752–56. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.752.

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Spreadspectrum orthogonal frequency-division multiplexing (SS-OFDM), which appliesspread spectrum technique into OFDM, performs robustly in severely multipathfading underwater channels. However, this technology is sensitive to thefrequency shift. Furthermore, communication in underwater acoustic (UWA)channels is more vulnerable to Doppler effect than other wireless channels dueto the low speed of acoustic signal propagation. It presents challenges forcommunication between underwater mobile nodes. Therefore, accurate Dopplerfrequency shift estimation and compensation is important. Aself-designed receiver structure for SS-OFDM system including a novel Dopplerscale estimation method and channel estimation via compressed sensing method isproposed. The simulation and experimental results offer strong proofs for ourscheme to be a viable option for acoustic communication between underwatermobile nodes and compressed sensing method outperforms the conventionalleast-squares (LS) method in channel estimation.

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Zhou, Jingchun, Dingshuo Liu, Xiong Xie, and Weishi Zhang. "Underwater image restoration by red channel compensation and underwater median dark channel prior." Applied Optics 61, no. 10 (March 30, 2022): 2915. http://dx.doi.org/10.1364/ao.452318.

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Journal articles on the topic 'Channel compensation'

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