The one-meter telescope at Weihai Observatory of Shandong University is an f/8 Cassegrain telescope. Three sets of filters, including Johnson-Cousins UBVRI, Sloan Digital Sky Survey u ′ g ′ r ′ i ′ z ′ and Strömgren uvby, are installed in a dual layer filterwheel. The photometric system and the CCD camera are introduced in this paper, followed by detailed analysis of their performances, and determination of the relevant parameters, including gain, readout noise, dark current and linearity of the CCD camera. In addition, the characteristics of the site astro-climate condition, including typical seeing, clear nights statistics, and average sky brightness were studied systematically based on data gathered from Sep. 2007 to Aug. 2013, and were reported in this work. Photometric calibrations were done using 8 nights Landolt standard star observations, which yielded transformation coefficients, photometry precision and system throughput. The limiting magnitudes were simulated using the derived calibration parameters and classic observation conditions at WHO.

To reduce the electromagnetic radiation emission intensity of airborne digital equipment， the spectrum of the digital signal is analyzed， revealing that the fundamental wave and its high-frequency har• monics are the sources of electromagnetic radiation emissions. Next， the rationale of shielding layer to sup• press electromagnetic radiation is analyzed. The results indicate that the high-conductivity non-magnetic shielding layer has a good shielding effect on the electric field and high-frequency magnetic field. The influ• ence of the gap on the shielding effectiveness of the shield is analyzed again， and a new method of doublelayer fill shielding is proposed and validated. Then， the absorption loss of the electromagnetic wave is ana• lyzed， and a new method for improving the shielding effectiveness of twisted-pair shielded cable/coaxial ca• ble double-layer shielding is proposed and validated. Finally， an actual engineering project is considered as 文章编号 1004-924X (2023)11-1660-12 收稿日期： 2023-02-13； 修订日期： 2023-03-02. 基金项目： 吉林省科技发展计划资助项目(No. 20200403057SF) 第 11 期 韩松伟， 等： 机载数字化设备屏蔽效能的提高 an example. The project equipment satisfies the GJB151B-2013 RE102 requirements and still interferes with the Beidou equipment Star(BDS) Searching and positioning. The electromagnetic compatibility is improved using the proposed method. After the improvement， the emission intensity of electromagnetic ra• diation is significantly reduced， by 12 dBμV/m on average. The ground and flight experiments verify that the integral power of the BDB1 and BDB3 frequency points is increased by 0. 59 and 1. 84 dBm， respec• tively， under normal operating conditions， and the number of BDS searching satellites is increased from ≤3 to ≥9， the BDS can operate normally.