Journal Of Geophysics Research

The principle of the seismograph and its. electronic feedback has been analyzed theoretically, and in the practice that abroad band seismometer modeled as BKD-2 is designed, improving the mechanism techniques and electronic feedback circuit, not only to extend its frequency band, and also to make it suit for movable observation application owing to its high reliability and stability which has been demonstrated in several field observation. The technique of the oven oblique axis of the STS-II seismometer is practiced in a new seismometer modeled as ACE-I.The digitalization technology of the earthquake observation is studied systematically, including 24 bits Z! - A analogy to digit conversion, function interface design of the embedded PC module, the integrated circuits realization using the FPGA technique and the GPS application. And as a result, Model ACE-I 24 bits earthquake acquisition device is developed which good performance is achieved including 24 bits AD resolution, wider than 120 dB dynamic range under several sample rates, etc. Its features such as high reliability, low consumption and large capacity of data storage showed better than common ones which make it suit for movable observation.The technique of fluxgate is analyzed theoretically including the output of the ringcore sensor, the exiting mode of the magnetizing coil, the method of the geomagnetic signal detection. A digital fluxgate magnetometer modeled as GM3 is first developed in our country, and its performance is comparable to the international similar ones.Considering that to calibrate the geomagnetic instruments is difficult and complex, and all calibrating system in existence in our country cannot satisfy the demand of high precision geomagnetic device, a tri-axis coil system is designed in which the geomagnetism is compensated by the feedback from a following fluxgate magnetometer. The features of this calibrating coil system are bigger magnetic even space, lower noise level, tri dimensional magnetism can be controlled manually and shielding the geomagnetism variety, which is be applicable for all geomagnetic devices.The experiments executed in this paper is to solve those problems that how to test the performance of the digital geomagnetic instruments newly devoted into the geomagnetic observatory, how to practice the new observing methods in which is current in the INTERMAGNET and how to determine the safe intervals between each kind of devices, which is important to develop digitalized observation in our country.