伪随机源直升机航空电磁宽频低噪接收优化设计

Optimization design of broadband and low noise receiving for helicopter⁃borne electromagnetic method with pseudo⁃random coded waveforms

针对200 kHz高频码元伪随机发射源,综合考虑灵敏度、信噪比等因素,在噪声水平低至4.86 nT/s前提下,将空心线圈传感器谐振频率提升至150 kHz以上;接收机基于PXIe总线,可实现三分量电磁数据、发射电流及辅助信息收录,采样率最高可达1.25 MHz,动态范围为112.6 dB。通过复合时间戳整合多通道信号、改进的多信息单文件存储方式,实现了大数据量下的多信息可靠存储,与传统的CHTEM-Ⅱ航空电磁收录系统相比,吞吐量提升了8倍。多种性能指标测试结果证明本文接收系统具有较高的完成度。

In this paper,aiming at the pseudo-random transmitting current of 200 kHz clock frequency,comprehensively considering factors such as sensitivity,signal-to-noise ratio,the resonant frequency of the air-core coil sensor is increased to above 150 kHz when the noise level is as low as 4.86 nT/s;The receiver is based on the PXIe bus,which can realize the acquisition of three-component electromagnetic data,transmitting current and various auxiliary information.The sampling rate can reach up to 1.25 MHz,and the dynamic range is 112.6 dB.Through the integration of multi-channel signals,improved multi-information single-file storage method and data storage protocols through composite time stamping,reliable multi-information storage under massive data is realized.Compared with the CHTEM-Ⅱairborne electromagnetic recording system,the throughput is up to 6 times.The test results of various performance indicators prove that the receiving system has a high degree of completion.