| Broadband seismometer’s performance impacts the quality of seismic observations. Now broadband seismometer commonly uses the force balance feedback technology to achieve broad observation band, large dynamic range target. But the analog feedback technology uses analog integrator based on operational amplifier, it may cause noise and drift in the feedback network and affect the seismometer, Analog integrator will inhibit seismometer’s performance.This paper studied on broadband feedback seismometer, explored new digital feedback technology to suppress broadband seismometer zero drift, improve the stability and optimize long-period noise, improve the quality of seismic records.The main idea of this paper is to build a new digital feedback seismometer based on digital feedback technology. According to the study on broadband seismometer feedback model, we used local digital feedback scheme based on integrator digitizing.In this research, we build hardware supporting system and embedded software system. The hardware system is digital integrator system. The software system is developed in chip with ARM Cortex-M0+ core, which can achieve numerical integrator and control the period、damp.We studied broadband seismometer developed in earthquake observation technology laboratory, digitized its feedback circuit, and tested its zero drift, noise and other indicators, the test results showed that: digital seismometer can achieve damp 0.707 and achieve different cycles, such as 60 s, 100 s, 120s; digital seismometer had a lower zero drift level and a better long period noise than the traditional broadband seismometer.The results show that the paper elaborated broadband seismometer digital transformation plan is feasible and effective, broadband seismometer has improved zero drift and long-period noise indicators. As while the function of instrument extends widely because of using the digital signal processing system, the seismometer realized programmable parameters such as the period. |
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