Weaver C S, Ramsey S D, Goodman J W, Rosie A M
Appl Opt. 1970 Jul 1;9(7):1672-82. doi: 10.1364/AO.9.001672.
The ease with which an optical system can achieve an extremely large time-bandwidth product makes optical filters and cross-correlation function generators attractive for signal detection and parameter estimation when signal-to-noise ratios are very low. The principles of a new optical filter that overcomes the sometimes severe positioning requirements of conventional optical filters are described. The relationship between the signal amplitude and matched-filter impulse response amplitude is discussed, and a method for reducing a noise component that is common to all optical filters is given. A matched filter was constructed and used to detect a radar-like pulse when the signal-to-noise ratio was -40 dB. A digital computer may be used with an optical system to filter time signals with an accuracy that potentially is as good as the accuracy of an all-digital system, but with a significant reduction in computation. The theory of an optical digital filter is presented.
光学系统能够轻松实现极大的时间带宽积，这使得光学滤波器和互相关函数发生器在信噪比极低时，对于信号检测和参数估计具有吸引力。本文描述了一种新型光学滤波器的原理，该滤波器克服了传统光学滤波器有时极为严格的定位要求。讨论了信号幅度与匹配滤波器脉冲响应幅度之间的关系，并给出了一种降低所有光学滤波器共有的噪声分量的方法。构建了一个匹配滤波器，并在信噪比为 -40 dB 时用于检测类似雷达的脉冲。数字计算机可与光学系统配合使用，以滤波时间信号，其精度可能与全数字系统的精度相当，但计算量显著减少。本文还介绍了光学数字滤波器的理论。
