デルタシグマDACを応用した衛星搭載用高精度ディジタル方式フラックスゲート磁力計の開発

• Material Type: 規格・テクニカルリポート類
• Title: デルタシグマDACを応用した衛星搭載用高精度ディジタル方式フラックスゲート磁力計の開発
• Author/Editor: 井口, 恭介; 松岡, 彩子; Iguchi, Kyosuke; Matsuoka, Ayako
• Author Heading: 井口, 恭介; 松岡, 彩子; Iguchi, Kyosuke; Matsuoka, Ayako
• Publication, Distribution, etc.: 宇宙航空研究開発機構(JAXA)
• Publication Date: 2013-03-29
• Publication Date (W3CDTF): 2013-03-29
• Alternative Title: Development of a Digital Fluxgate Magnetometer using a Sigma-Delta DAC for Spacecraft Applications
• Periodical title: 宇宙航空研究開発機構研究開発報告: デルタシグマDACを応用した衛星搭載用高精度ディジタル方式フラックスゲート磁力計の開発
• No. or year of volume/issue: JAXA-RR-12-008
• Volume: JAXA-RR-12-008
• Pages: 1-80
• ISSN (Periodical Title): ISSN : 1349-1113
• Text Language Code: jpn
• Subject Heading: fluxgate magnetometer; sigma-delta DAC; plasma physics; The sounding rocket mission; S-310-40; The SCOPE mission
• Target Audience: 一般
• Note (General): Fluxgate magnetometers are most widely used for space science missions to measure the Earth, planetary and interplanetary magnetic field. For future missions (e.g., the cross-Scale COupling in the Plasma universE (SCOPE) mission), it is required to further reduce the resources of instruments as well as to improve the resolution (>20 bits) of the existing magnetometers. The digital-type fluxgate magnetometer has more advantage of being small, light-weight and low power consumption than the conventional types. Its accuracy is determined by the accuracy of the Digital-to-Analog Converter (DAC) in the electronics circuit. The commercial DAC for the space applications does not have better resolution than 12 bits, and is not applicable for the high-resolution digital-type fluxgate magnetometers. As the interim goal for future missions, we designed a 16-bit sigma-delta DAC, in order to improve the accuracy of the digital-type fluxgate magnetometer. The resolution of the sigma-delta DAC depends on the design of the sigma delta modulator and the performance of the analog low-pass filter. It is important to optimize the sigma-delta DAC's design by numerical simulation to achieve the 16-bit resolution. The optimized design of the sigma-delta DAC is described as; ・2nd-order 1-bit Boser-Wooley type sigma-delta modulator ,; ・4th-order, Butterworth type analog low-pass filter,; ・Over Sampling Ratio is 677.; The sigma-delta DAC circuit was built using space-use or equivalent parts, and its performance was evaluated experimentally. The resolution of the sigma-delta DAC was approximately 18 bits.The linearity error was better than 0.01 %F.S. The cut-off frequency was 67 Hz. A Digital-type FluxGate magnetometer (DFG) was built using the developed sigma-delta DAC. The resolution of DFG was 0.79 nT which corresponds to the 17.1-bit resolution and satisfies the interim goal resolution (16 bits). The sensitivity and measurement alignment of DFG were accurately calibrated in the magnetic observatory. DFG was installed on the sounding rocket S-310-40 to determine the spin frequency of the rocket and the magnetic field direction with respect to the rocket spin axis. DFG worked successfully and the spin frequency was well determined through the flight of the rocket. However, in the process to derive the angle between the magnetic field and the rocket spin axis, significant (1800 nT) variation of the calculated magnetic offset along the spin axis was found. Since such a large variation of the offset during the flight is improbable, the sensitivity of DFG was calibrated again using the flight data. Based on a comparison of the sensitivity parameters between ground calibration and the flight data, in the case of the S-310-40 experiment, the accuracy of the determined magnetic angle was 5 degrees which does not satisfy the required accuracy (2 degrees). There are several possible reasons why the sensitivity varied after the ground calibration test; e.g. the temperature characteristics of parts used for DFG. The drift of the sensitivity should be reduced for more accurate measurement of the magnetic angle. The temperature characteristics of the sigma-delta DAC should be examined in detail for the development of the magnetometer for future space missions.; 形態: カラー図版あり; Physical characteristics: Original contains color illustrations; 資料番号: AA0061887000; レポート番号: JAXA-RR-12-008
• Access Restrictions: インターネット公開
• Periodical Title (NCID): AA1192675X; https://ci.nii.ac.jp/ncid/AA1192675X
• Data Provider (Database): 国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）; https://irdb.nii.ac.jp
• Original Data Provider (Database): 宇宙航空研究開発機構 : 宇宙航空研究開発機構リポジトリ

• Summary, etc.: 人工衛星搭載フラックスゲート磁力計を用いた磁場の「その場観測」は，宇宙プラズマの研究に必要不可欠である．複数衛星による同時多点観測ミッションや木星などの磁気圏探査ミッションでは，搭載機器の重量や電力に厳しい制限がある．磁力計を小型軽量・省電力化するために，1990年代にはディジタル方式フラックスゲー...