Error Compensation Software to Remove the Low-Frequency Error of Aluminum Freeform Mirror for an Infrared Off-Axis Telescope

2021 ◽  
Vol 38 (5) ◽  
pp. 329-336
Author(s):  
Tae-Geun Ji ◽  
Dae Wook Kim ◽  
Woojin Park ◽  
Soojong Pak ◽  
Byeongjoon Jeong ◽  
...  
Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 553
Author(s):  
Daewon Chung ◽  
Woon Cho ◽  
Inyeob Jeong ◽  
Joonhyeon Jeon

Maximally-flat (MAXFLAT) finite impulse response (FIR) filters often face a problem of the cutoff-frequency error due to approximation of the desired frequency response by some closed-form solution. So far, there have been plenty of efforts to design such a filter with an arbitrarily specified cut off-frequency, but this filter type requires extensive computation and is not MAXFLAT anymore. Thus, a computationally efficient and effective design is needed for highly accurate filters with desired frequency characteristics. This paper describes a new method for designing cutoff-frequency-fixing FIR filters through the cutoff-frequency error compensation of MAXFLAT FIR filters. The proposed method provides a closed-form Chebyshev polynomial containing a cutoff-error compensation function, which can characterize the “cutoff-error-free” filters in terms of the degree of flatness for a given order of filter and cut off-frequency. This method also allows a computationally efficient and accurate formula to directly determine the degree of flatness, so that this filter type has a flat magnitude characteristic both in the passband and the stopband. The remarkable effectiveness of the proposed method in design efficiency and accuracy is clearly demonstrated through various examples, indicating that the cutoff-fixing filters exhibit amplitude distortion error of less than 10−14 and no cut off-frequency error. This new approach is shown to provide significant advantages over the previous works in design flexibility and accuracy.


2020 ◽  
Vol 49 (1) ◽  
pp. 112005-112005
Author(s):  
金荷 He JIN ◽  
毛晓楠 Xiao-nan MAO ◽  
李新鹏 Xin-peng LI ◽  
余路伟 Lu-wei YU ◽  
任平川 Ping-chuan REN

2017 ◽  
Vol 46 (7) ◽  
pp. 717006
Author(s):  
胡雄超 Hu Xiongchao ◽  
毛晓楠 Mao Xiaonan ◽  
吴永康 Wu Yongkang ◽  
闫晓军 Yan Xiaojun ◽  
余路伟 Yu Luwei ◽  
...  

1985 ◽  
Vol 58 (3) ◽  
pp. 1026-1030
Author(s):  
D. D. Hickey ◽  
J. Zaharkin

A low-frequency response analysis of three Grass model 7 polygraphs was undertaken. Observed error was generally found to fall within the manufacturer's stated range of +5 to -10% of DC signal height over the frequency range of human respiration (0.1–3 Hz), but this was not the case for frequencies greater than 6 Hz under certain circumstances. The magnitude of error was seen to vary directly with frequency and indirectly with pen-deflection amplitude and paper speed. The pen-oscillograph apparatus was the predominant source of low-frequency error, and this is probably due to pen inertia and pen friction on the writing surface. Two schemes to reduce such error are presented.


2012 ◽  
Vol 6 (3) ◽  
pp. 384 ◽  
Author(s):  
K. Xiong ◽  
C.Q. Zhang ◽  
L.D. Liu

2019 ◽  
Vol 54 (7) ◽  
pp. 1952-1959 ◽  
Author(s):  
Ningxi Liu ◽  
Rishika Agarwala ◽  
Anjana Dissanayake ◽  
Daniel S. Truesdell ◽  
Sumanth Kamineni ◽  
...  

Author(s):  
Mi Wang ◽  
Chengcheng Fang ◽  
Bo Yang ◽  
Yufeng Cheng

The low frequency error is a key factor which has affected uncontrolled geometry processing accuracy of the high-resolution optical image. To guarantee the geometric quality of imagery, this paper presents an on-orbit calibration method for the low frequency error based on geometric calibration field. Firstly, we introduce the overall flow of low frequency error on-orbit analysis and calibration, which includes optical axis angle variation detection of star sensor, relative calibration among star sensors, multi-star sensor information fusion, low frequency error model construction and verification. Secondly, we use optical axis angle change detection method to analyze the law of low frequency error variation. Thirdly, we respectively use the method of relative calibration and information fusion among star sensors to realize the datum unity and high precision attitude output. Finally, we realize the low frequency error model construction and optimal estimation of model parameters based on DEM/DOM of geometric calibration field. To evaluate the performance of the proposed calibration method, a certain type satellite’s real data is used. Test results demonstrate that the calibration model in this paper can well describe the law of the low frequency error variation. The uncontrolled geometric positioning accuracy of the high-resolution optical image in the WGS-84 Coordinate Systems is obviously improved after the step-wise calibration.


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