海底天然地电信号采集的实时级联分样技术

Real-Time Cascade Decimation for Seafloor Data Acquisition of Magnetotelluric Field

针对海底天然地电场信号幅度小、超长周期的特点,提出对原始地电观测数据进行实时级联分样的技术.运用变采样率的方式进行数据采集.在数存空间内,依据奈奎斯特定理和最大误差最小化的原则,设计多级抗混叠数字滤波器,使实测数据经过滤波器后,达到无失真抽样与存储的目的.在海底测量时,不同级的分样数据对应着不同采样率的测试结果,各级的分样构成全频段的地电信息.经海试检验证实,本文所提出的实时级联分样技术为海底以下的资源探测提供了一种有效的信息提取手段.

A real-time cascade decimation technique is developed for undistorted sampling from observational data of seafloor magnetotelluric signals which are characterized by small amplitudes and super long periods. In data space, multi-stage anti-aliasing digital filters are designed on the basis of the Nyquist sampling theorem and the minimax criterion to ensure that the observational data are sampled and stored without distortion. While taking seafloor measurements, different sampling rates are set for different frequency bands; the decimated data on different stages represent the results at different sampling rates and can ultimately be jointed to provide geoelectric information on all frequency bands. Seafloor experiments suggest that the real-time cascade decimation techniaue is efficient method in collection of information for seafloor resource exploration.