Design of an Upgraded Electronics Control System for An Advanced Lidar Atmospheric Profiling System
Document ID: 84
Master's Thesis
The Pennsylvania State University
The Graduate School
Department of Computer Engineering
Abstract
The PSU Lidar Atmospheric Profile Sensor (LAPS) instrument has been used to measure a variety of atmospheric properties including water vapor, temperature, optical extinction and ozone since its design and construction in 1995. Originally designed for the US Navy as an ADM (Advanced Development Model) prototype, the system has since changed its role to a more research oriented tool after being used to demonstrate its ability to meet the required performance goals. It is currently being used as a test-bed for concepts to be integrated into the next generation Advanced LAPS (ALAPS) unit which will be the EDM (Engineering Design Model) used to demonstrate the fit form and function prior to commercial development. Changes in the intended usage of the system, as well as various shortcomings noted in the original design during the six years of its operation, have motivated the need for a redesign of the control computer system for the unit. This update was seen as a first step in moving towards the ALAPS system. In order to meet the new requirements as a research tool, a system with a great deal of flexibility was desired while increasing reliability over the current version. The original system was based on the aging and essentially outdated STD bus standard which is being phased out, hence the more current PC/104 standard has been used to allow future addition of new peripheral devices. Another significant goal was to use the largest possible amount of Commercial Off The Shelf technology (COTS) hardware possible since this will ease repair of the unit, reduce costs, and ease its eventual transition to a manufactured system.
In addition to these main goals, advances in the computer industry as well as reductions in electronics size have led to the possibility of moving portions of the electronics which currently reside outside the system into the interior of the unit. This redistribution of system electronics will shift a large part of the computing requirements from the external console computer to the internal deck computer. This computer must be able to handle the new data processing and information serving roles while maintaining a fast response to time-critical systems For these reasons, the RT-Linux operating system was chosen to drive the new computer system since it allows for remote access, file serving, hard real-time performance as well as providing good stability with a minimum amount of overhead. Digital and analog signal conditioning modules are also used to provide both electrical isolation and flexibility in the new system.
| Citation: | A. D. Achey, "Design of an Upgraded Electronics Control System for An Advanced Lidar Atmospheric Profiling System", The Pennsylvania State University, Master's Thesis, May 2002, 77 pages |