An Atmospheric Lidar Data-Acquisition System Using an On-Line Digital Computer

摘要

The report describes the design and operation of a data-acquisition system which uses digital circuits and an on-line PDP-8/I computer for real-time data processing to make upper atmospheric LIDAR measurements. The system is presently being used with the high-power pulsed ruby laser which has recently been installed at the Mount Haleakala Observatory, Maui, Hawaii. The report discusses the basic concepts involved in obtaining LIDAR measurements of atmospheric backscattering. Expected signal returns for both the 'current' (lower atmosphere) and pulse-counting (upper atmosphere) cases are calculated. Noise and background sources are considered in detail, and the statistical nature of the upper atmospheric experiments is emphasized. Detailed circuit diagrams for the data acquisition system and a LIDAR data-acquisition program for the PDP-8/I computer are also included. Preliminary data obtained with the LIDAR system is presented and compared with prediction. (Author)