基于光学调制的离焦探测技术

通过对常用离焦检测技术的分析,提出了一种基于空间光学调制的离焦探测新方法。该方法利用压电陶瓷驱动变形镜对会聚光束进行调制,在准焦位置放置针孔(或狭缝),通过针孔(或狭缝)的调制光束被光电探测器接收,经相关检波后获得离焦信息。测得的离焦信息包含离焦量和离焦方向,且离焦信号电压与离焦量呈线性关系。搭建了实验装置,利用100 Hz的正弦信号对光束进行调制,检波后得到了焦前4 mm到焦后2 mm范围内的电压信号,结果与理论推导相符。该技术适用于圆对称光束及非圆对称光束的离焦检测,尤其适于具有柱面镜光路结构、需要快速、准确测量x和y方向离焦量的强激光领域。

具有开放气室的实时红外气体检测系统

介绍了一种具有开放气室的实时红外气体检测系统。系统由Silicon Lab C8051F060单片机控制,选用MEMS红外光源和光电二极管红外探测器,依据相关检波基本原理设计了信号调理电路。对乙醇和甲烷气体的测量实验表明:在16 Hz的光源调制频率下,系统具有较高的灵敏度和信噪比。

航管应答机的中频数字化设计

提出了一种航管应答机的中频数字化设计方案,并详细论述了如何应用带通采样定理、正交相干检波理论实现接收信号的中频直接数字化,同时对高速模拟/数字变换器(ADC)、低通滤波器、基带信号处理等各主要功能模块进行了介绍,并给出了相关的计算和仿真。

日本近炸引信开发动向

本文对日本制导导弹引信,地空导弹引信、机载炮弹频率跳跃式近炸引信及能够击毁导弹上、下方向目标的主动近炸引信作了概述。这些引信对我国近炸引信研制和火工品防干扰措施具有参考价值。

瞬时频差测试

频率捷变雷达的快速发展对本地振荡器的跟踪速度及跟踪精度有了更高的要求，本文介绍了一种瞬时测试RF与LO频差的方法。

Harmonic detection an AC excited generation system based on in-phase correlation filtering

The paper reports results of investigation on the harmonic detection technique of a complicated power supply system such as an AC excited generation system, which has a variable fundamental frequency and low order harmonics with rich sub-harmonics whose frequencies are lower than the fundamental one. The in-phase correlation filtering technique, based on the frequency shifting principle, is proposed in this paper.Theoretical analysis and experimental results validate the effectiveness of this technique for the harmonic detections of AC excited generation systems.

Using acoustic technique to detect leakage in city gas pipelines

For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic theory of leakage detection and location was introduced. Then the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HILBERT-HUANG transformation (HHT), the instantaneous energy distribution feature of an unstable acoustic signal was obtained. According to the relative contribution method of the instantaneous energy, the noise in signal was eliminated effectively. Furthermore, in order to judge the leakage, the typical characteristic of the instantaneous energy of signal in the input and output end was discussed using correlative analysis. A number of experiments were carried out to classify the leakage from normal operations, and the results show that the leakages are successfully detected and the average recognition rate reaches 93.3% among three group samples. It is shown that the method using acoustic technique with IED and correlative analysis is effective and it may be referred in other pipelines.

转换波静校正技术在四川地区的应用研究

转换波静校正问题一直被认为是转换波处理中较难解决的问题,目前已研究的方法都存在一定的局限性.针对四川盆地川中地区实际情况,本文提出一种组合的转换波静校正方法.首先,根据采集的三分量微测井资料计算低降速层的纵、横波平均速度比,再利用该速度比与纵波的检波点静校正量相乘计算得到转换波长波长静校正量;然后,应用改进的共检波点叠加互相关法求取转换波短波长静校正量;最后,利用分频地表一致性剩余静校正求取剩余静校正量.实际数据处理表明,该转换波静校正技术能够较好地解决四川地区转换波静校正问题,使地震资料的成像效果得到明显的改善.