Zhuang Cantao

Development of China digital seismological observational systems

Development of China Digital Seismological Observational Systems during 1996~2000 and the Capital Circle Area Seismograph Network during 1999~2001 are introduced, and the station distributions, instruments used, main tasks of National Digital Seismograph Network, Regional Digital Seismograph Network and Portable Digital Seismograph Network are introduced chiefly.

Transfer function of FBS-3A feedback broadband seismometer

FBS-3A feedback broadband seismometer has been widely utilized in observation networks up to now. Therefore, it is very important and practically meaningful for the application of this kind of sensor to fulfill some relative research work about its transfer function and for the analysis to the data recorded and the further development of the seismometer. In this paper, from the viewpoint of achieving its working principle, method of systematic analysis is applied to deduce the transfer functions, including both the transfer function for calibration and that for measurement. Moreover, on the basis of that, the distribution of its zeroes and poles in a complex frequency domain is analyzed, which provides a convincing evidence to simplify this seismometer sytem from a high-order one to a two-order one. And the emulation of the frequency characteristics of FBS-3A is presented in this paper. On the whole, the aim of this article is to do some theoretical work about the earthquake observation sensor, and also to introduce the method of making systematic analysis in a complex frequency domain to the research and the development of the seismometers.

A network communication and recording system for digital seismic observation

A network communication and recording system based on China-made ARCA SOC and embedded Linux operating system is introduced in this paper. It supports TCP/IP network communication protocol and mass storage medium. It has strong points of self-monitor, low power consumption, high timing accuracy, high reliability of operation, etc. It can serve up to 20 centers real-time waveform data at the same time. It meets not only the requirements of physical metworking observation, but also virtual networking observation based on Internet in which real-time data transmission is required. Its ability of field recording also meets the requirements of portable seismic observation, strong motion observation and seismic exploration observation, etc.

On the calibration of feedback broadband seismometer FBS-3A with current signal

With the time passing by and the environment changing, the characteristics of the components in a seismometer may change a little to some extent. To realize this kind of change and take steps to control or adjust it is helpful to improve the reliability of the sensor’s output. Therefore, every seismometer must be calibrated, either before leaving factory or in use. Up to now, there are two kinds of calibrations used frequently with current signals, namely using square-wave signal and sine-wave signal. From the view point of systematic analysis, after getting the transfer function of the seismometer and simplifying the process of calibration with current signal, research has been done, in complex frequency domain, to the process of calibration with simulation method. On the basis of this, the relationship between the output figure of square-wave calibration and the intrinsic parameters of a sensor is discussed in this paper. The relationship between the steady output of sine-wave calibration and the calibration current, as well as the relationship of the calibration outputs caused by two sine waves with specific frequencies is presented. As the result of the theoretical analysis, two applications of the calibration with current signal are provided. The aim of this paper is to clarify the meanings of these two commonly used calibration methods, which would be fairly positive and helpful to the adjustment and the practical application of the seismometers.