A theoretical model of the seismometer self‐noise can be used to predict the self‐noise. Its inputs are mechanical and electrical parameters of the seismometer. In this article, we studied the theoretical model of the self‐noise of the velocity‐broadband seismometer, using the CS60 seismometer as an example. Velocity‐broadband seismometer is a type of feedback seismometer. The previous theoretical model of the self‐noise of the feedback seismometer only involved noise sources in the forward path of the feedback system. Our model involved not only noise sources in the forward path, but also noise sources in the feedback path and external to the feedback loop.We introduced noise sources in the feedback system of the seismometer and the method of calculating their levels with mechanical and electrical parameters, developed expressions for referring all noise sources to the input terminal of the feedback system, and finally established the model. We compared the CS60 seismometer’s predicted self‐noise calculated using this model with the measured self‐noise, and we found good agreement between them.The contribution of each noise source to the total noise was studied, and it was found that the dominant noise source in CS60 is different over different frequency bands. Over the frequency band below 0.0095 Hz, the noise of the integrator (in the feedback path) is the dominant noise source. Over the frequency band from 0.0095 to 0.21 Hz, suspension noise is the dominant noise source. Over the frequency band from 0.21 to 39 Hz, the noise of the differential driver (external to the feedback loop) is the dominant noise source. Over the frequency band above 39 Hz, the noise of the preamplifier (in the forward path) is the dominant noise source. In addition, some viewpoints about the low‐noise design of seismometers were proposed.

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速度宽带地震仪自噪声的理论模型

地震仪自噪声的理论模型可用于预测自噪声。它的输入是地震仪的机械和电气参数。在本文中，我们以CS60地震仪为例研究了速度宽带地震仪自噪声的理论模型。速度宽带地震仪是一种反馈式地震仪。先前反馈地震仪自噪声的理论模型仅涉及反馈系统前向路径中的噪声源。我们的模型不仅涉及正向路径中的噪声源，还涉及反馈路径中和反馈回路外部的噪声源。 , 开发了将所有噪声源引用到反馈系统输入端的表达式，并最终建立了模型。我们将使用该模型计算出的 CS60 地震仪的预测自噪声与实测自噪声进行了比较，发现两者之间具有良好的一致性。 研究了每个噪声源对总噪声的贡献，发现主要噪声源CS60 在不同的频段上是不同的。在 0.0095 Hz 以下的频带内，积分器的噪声（在反馈路径中）是主要的噪声源。在 0.0095 到 0.21 Hz 的频带内，悬浮噪声是主要的噪声源。在 0.21 至 39 Hz 的频带内，差分驱动器的噪声（反馈环路外部）是主要噪声源。在 39 Hz 以上的频段上，前置放大器的噪声（在前向路径中）是主要的噪声源。另外，提出了关于地震仪低噪声设计的一些观点。