Joe DeRosa

A simple calculation is made for the power spectral density (psd) of a sinusoid phase modulated by a filtered Gaussian process. The premodulation filter has a Gaussian-shaped frequency response. Design curves are presented for the out-of-band interference, the in-band power, and the psd in terms of the premodulation filter's bandwidth and the rms modulation index.

The objective of this effort was to discover patterns of success in the systems engineering of information-intensive systems in a government acquisition environment using the method of positive deviance. Thirty government programs were identified, each with some notable success in the acquisition of IT-intensive capabilities. Twelve were selected for extensive follow-up and analysis, including detailed interviews with front-line practitioners who cope with the demands of the government acquisition system and are in a position to influence or observe positive deviance in their environment. This paper describes two large-scale success patterns that were observed, each with several recurring sub-patterns. “Balancing the Supply Web” addresses “social” interdependencies among enterprise stakeholders who have different equities in the capability being developed. “Harnessing Technical Complexity” addresses the technical interdependencies among system components that together deliver an operational capability for the enterprise. The large-scale patterns are two sides of the same coin. The programs studied achieved success because of the way they each navigated through these dual interdependencies.

This paper describes how to use a positive deviance-inspired process for improving the practice of systems engineering, and how positive deviance fits into an evolutionary improvement strategy. It illustrates the process with examples from both systems engineering and cases studies outside of systems engineering. In particular we cite the experience of the team that authored the DoD systems engineering guide for systems of systems (SoS) [Ref 1]. They developed a representation of how successful SoS engineering practitioners view and do systems engineering that is substantially different from their individual system counterparts. The cases outside of systems engineering relate to an antistarvation program in rural Vietnam and a 150-year old problem of inadequate hand scrubbing and infections in hospitals [Ref 2]. Even with substantial progress in technology, processes, and efficiencies, complex problems from enterprise systems engineering to nutrition to medical needs still stubbornly resist improvement. By using a positive deviance-inspired approach, this can be reversed.

This paper gives an extensive analysis of a Packet satellite (PACSAT) communications system that uses a digital processing satellite in a packet data network. It is shown that multiple uplinks coupled with on-board switching and storage can provide significant gains in throughput, efficiency, and margin against instability. Design tradeoffs are presented and the theoretical results are verified by extensive computer simulations.

This brief note represents a simple but significant change in the thinking that is applied to satellite packet switching. It demonstrates that in a precessing satellite there is no fundamental limitation to the efficiency and throughput of packet switching systems. With a minimal impact on spacecraft weight and power, throughput is increased by providing more capacity on the uplink than on the downlink. Efficiency is increased because the power-intensive downlink is more fully utilized. A slotted ALOHA example is given to show how the performance can be made to go from that of conventional slotted ALOHA to that of a TDM system. Several possible variations and far-reaching implications are indicated.

This study is concerned with high data rate transmission/unit bandwidth over line-of-sight (LOS) microwave relay systems, which are an important element of the Defense Communication System (DCS). Most attention has been given to developing concepts for and evaluating the performance of high bits/sec/Hz modem techniques that could be used effectively with the DCS LOS microwave relay links, taking due consideration of the limitations imposed by the propagation medium, by military bandwidth constraints, and by existing equipments in the DCS.