Unix and the Real-Time Telemetry System

Abstract

Since the first computer-based telemetry systems were designed in the mid-1960's, the operating system has been the nemesis of the system software designer. The requirement to acquire telemetry data at high rates, in real time, without loss, is in direct conflict with the direction computer operating systems have taken over the last two decades. The "lean and mean", single user operating systems of the 1960's have been replaced by multi-tasking, multiuser systems which emphasize multiple applications at the expense of real-time performance. Recently, there has been enormous interest in hosting real-time telemetry systems under the UNIX operating system. From an applications standpoint UNIX has much to offer the user but it certainly complicates the life of the real-time system software designer. In this paper, a critical look is taken at the role of the operating system in a real-time telemetry system with particular emphasis on the use of UNIX POSIX and realtime extensions.