| Seismometer is the most effective means to observing earth's inner information and seismic activity. Development of seismometers has experienced a process from simple to complex and from analog to digital. From 1970s on, digital seismic observation technology has continually made progress. Some good-performance seismometers have been produced overseas, such as STS-1, STS-2, GMT-3, KS-36000, etc, and JCZ-1 Ultra Broadband Seismometer and CTS-1 Very Broadband Seismometer have been developed in China. In the year of 2000, China successfully built China National Digital Seismic Network that has the most broad band in the world, which made Chinese seismic observation technology enter the advanced ranks of the world.Traditional calibration methods cannot be used in seismometers with high-precision, wide dynamic range and broadband. Thus a lot of new methods for calibrating digital broadband seismometer have been researched at home and overseas. Because JCZ-1 Ultra Broadband Seismometer and CTS-1 Very Broadband Seismometer have very wide frequency band, very high precision, very large dynamic range and good linearity, precision of calibrating seismometer must be greatly raised in order that seismic recording data with high-precision are obtained. In the ninth and the tenth five-year plans of our country, Ultra Broadband and Very Broadband Seismometers are widely applied to China National Digital Seismic Network. In order to complete production and test of seismometers and network building in short time, it is required that seismometer's calibration and test be very efficient. Therefore, domestic and international existing calibration methods cannot meet demands at precision and efficiency of calibrating Ultra Broadband and Very Broadband Seismometer.Aimed at characteristics of JCZ-1 and CTS-1 Seismometers, this paper focuses on precise calibration techniques for Ultra Broadband and Very Broad Band Seismometer, achieves aims of high-precision and high-efficiency for calibrating Ultra Broadband and Very Broad Band Seismometer. Main contents of this paper include frequency-domain calibration technique, time-domain calibration technique, compare-test method of seismometer's sensitivity, time-frequency-domain fast calibration method and so on.Frequency-domain calibration technique includes computer-controlled sine-wave calibration method, noise pretreatment method in frequency-domain and vertical cross correlation method, etc. Computer-controlled sine-wave calibration method adopts high-precision analog-digital converter to record calibration output signal, carries out automatic calibration for Ultra Broadband and Very Broad Band Seismometer, which can raise calibration precision and efficiency. The key of data processing in frequency-domain is noise processing. Various treatment methods are discussed for different noise in frequency-domain calibration, and an obtaining long-period shift method by sine-wave envelopes isdetailed against long-period non-linearity shift, which effectively removes long-period shift noise. Vertical cross correlation method resolves problems of calibrating seismometer in condition of noise. Its very strong reduction ability of random noise can make signal extract from noise while signal completely submerging in noise and it has comparatively high precision. Especially, vertical cross correlation method also has very high test precision in high frequency end and long period band that traditional calibration methods cannot test.Time-domain calibration technique includes dynamic weight fit method, method of extracting low-frequency response and noise processing method in step calibration. Step signal, which is used as a time-domain calibration signal, is especially propitious to calibrating low-frequency transfer function of seismometer. Dynamic weight fit method is based on step calibration. By building theoretic weight model and iterative operation, it can acquire theoretic model's parameters, which are parameters of pending seismometer. Dynamic weight fit method has strong ability of red...
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