Modern aerogeophysical surveying over Antarctic terrain requires an efficient real-time data visualization system to monitor the high-speed acquisition of geophysical and navigational data. Real-time visualization quickly uncovers instrumentation problems, informs aircraft operators of data quality, and speeds the recognition of significant geophysical anomalies interpreted from the acquired data. Efficient routing of data packets demands a capable real-time operating system that is able to route data packets to multiple display stations, concurrently, with directing high-speed data acquisition.
The first part of this thesis describes a mobile, real‑time data visualization sub-system used during airborne geophysical surveys in Antarctica. The data acquisition machine is a twin otter aircraft outfitted with geophysical and navigational instrumentation allowing it to fly over ice fields and collect data used for geologic assessment of the surveyed areas. The aircraft computer system operates as a distributed network controlled by QNX, a Unix-based, real‑time operating system. QNX inter-process communication is based on message passing which is used extensively during data acquisition and visualization. The acquisition system, and real-time display sub-systems run as separate QNX processes on separate computers. All data streams entering the acquisition system are saved as stream-tagged, time-stamped, data packets. Real-time display processes request data packets from the acquisition system and extract the information to be displayed. Packet routing processes route data packets from the acquisition computer to real-time display stations via an Ethernet. Eight weeks of field use in Antarctica show that a visually interesting and informative real-time display provided system operators with a better window for monitoring data quality and instrument performance and quickly pointed out data errors due to equipment malfunction and outside-of-system interference.
The second part of this thesis presents an improved packet routing mechanism that more effectively routes data packets to the visualization stations. The improved design utilizes message queues, and multiple concurrent threads communicating, asynchronously, with the display sub-systems. A performance analysis compares this new improved mechanism with the original packet routing scheme under normal and increasing data loads. Using this new design, higher packet throughputs and lower packet latencies are measured at the real-time visualization sub-stations.