TABLE OF CONTENTS Preliminary design starts with the functional baseline defined during conceptual design and continues with the effort to translate system-level functional requirements into design requirements for the subsystems that will be combined to form the system. This translation requires a continuation of the requirements analysis started in conceptual design. Specific requirements for the hardware, software, and personnel making up the system need to be determined. Trade-off studies are conducted, and the result of the preliminary design effort is the establishment of an allocated baseline, where requirements are allocated to specific subsystems making up the system.
Responsibility for performing preliminary design normally rests with the contractor, who accepts responsibility for the system meeting the requirements of the functional baseline (normally prepared by the customer). The customer's role now increasingly becomes one of monitoring, reviewing, and supporting contractor progress. The customer normally avoids becoming actively involved in design decisions made during preliminary design (or any subsequent activity, for that matter), as the responsibility for the resultant functionality and performance of the system rests with the contractor.
In many cases, the customer may opt to add an additional level of rigor to the process by engaging independent systems engineering consultants to provide independent review of the many and varied engineering documents and products produced by contractors during the course of a systems development.
The activities conducted during the preliminary design effort include subsystem requirements analysis, subsystem requirements allocation, subsystem synthesis and evaluation, and preliminary design review (PDR). These tasks are illustrated...
