Feasibility study on Digital Feedback Seismometer

数字反馈地震仪可行性研究

• 批准号: 13640419
• 负责人: MORITA Yuichi
• 金额: $ 2.18万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640419/
• 关键词: seismometer; seismometory; broadband seismometer; digital signal processor; digital feedback system

An application of digital feedback system to a broadband seismometer (we call it digital a feedback seismometer : DFS, hereafter) is one of hopeful ways to improve the conventional broadband seismometers that is based on analog feedback system. The DFS seems to make the operation easier, measurement more precisely and observations more flexible, because it can compensate the error and non-linearity in the measurements and can adjust its frequency response to the target of the observation without any change in its hardware. The concept of the DFS has been proposed a few tens years ago firstly, but it has not been developed and has not been produced in commercial base in present. It is because that the technical problems on the DFS can not be solved now.In this study, we checked difficult points for realizing the DFS, evaluated their effects and revealed a possible solution on it, using the numerical simulation and experiments on the electronic circuits composed of DSP (digital signal processor). The effect of quantum errors of AD and DA converters, delay time caused by feedback calculation and AD-DA conversion give the limitation of the dynamic range in the DFS. It seems to be the most serious defect. However, we can solve this problem using the over-sampling techniques and filtering ones even in the case that we choose the realistic electronic devices that can be got by commercial base. For example, SAR type AD and DA converter with 16bits resolutions and digital signal processor with the speed of 40 MIPS realize the DFS with dynamic range of 140dB, which is almost compatible with the conventional broadband seismometers. It shows that the DFS is feasible to develop, and it encourages us to realize the DFS with high performance.In this study, we developed a prototype of a DFS using a DSP and mass-pendulum system to measure ground motion. I would like to carry out the advanced research to realize more realistic DFS in future study using this prototype.

将数字反馈系统应用于宽频带地震计（以下称之为数字反馈地震计DFS），是改进传统的基于模拟反馈系统的宽频带地震计的一个有希望的途径。由于DFS可以补偿测量中的误差和非线性，并且可以在不改变硬件的情况下根据观测目标调整其频率响应，因此使操作更简单，测量更精确，观测更灵活。DFS的概念早在几十年前就已提出，但目前还没有得到开发，也没有商业化生产。本文通过对DSP（Digital Signal Processor）构成的电子电路进行数值模拟和实验，对实现DFS的难点进行了分析，并对它们的效果进行了评价，提出了一种可行的解决方案。由于AD和DA转换器的量子误差、反馈计算和AD-DA转换引起的延迟时间的影响，DFS的动态范围受到限制。这似乎是最严重的缺陷。然而，我们可以解决这个问题，使用过采样技术和滤波的情况下，我们选择的情况下，我们可以得到现实的电子设备，可以通过商业基地。例如，采用16位分辨率的SAR型AD/DA转换器和40 MIPS的数字信号处理器，实现了动态范围140 dB的DFS，与传统的宽频带地震仪几乎兼容。本研究利用DSP和质量摆系统，研制了一台用于地面运动测量的DFS系统样机。我想在以后的研究中使用这个原型进行更深入的研究，以实现更真实的DFS。

项目成果

森田 裕一(分担著): "第5章「地球の鼓動を測る」"地殻ダイナミクスと地震発生(菊地正幸編)(朝倉書店). 222 (2002)

森田佑一（合著者）：“第5章“测量地球的心跳””地壳动力学和地震发生（菊池雅幸编辑）（朝仓书店）222（2002）。

Yuichi MORITA , editied by Masakuki KIKUCHI: "Measurements of Earth's vibration, in"Dynamics of crust and Earthquake generation""Asakura Publishing co.. (2002)

森田雄一，菊池正作主编：“地球振动的测量，载于‘地壳动力学和地震发生’”朝仓出版社（2002年）

森田裕一(分担著): "地殻ダイナミックスと地震発生(菊地正幸編) 第5章「地球の鼓動を測る」"朝倉書店. 222 (2002)

森田雄一（合著者）：《地壳动力学与地震发生》（菊池正幸主编）第 5 章“测量地球的心跳”》朝仓书店 222（2002 年）。