The design requirements are in several documents:

• Operational concept - A high level of how the whole system will work from a user perspective. It draws strongly from Evans's book, lists assumptions and constraints and rough schedule.
• Functional Requirements -  is going to define functionality DUH!!! (document is incomplete).
•  System Design - is going to define system relationship between hardware & software, includes safety, constraints and assumptions.  This will be the link between hardware and software requirements (document is incomplete).
• Hardware requirements specification - is going to define hardware components the system will be made of will include the system and component drawings.
• Software requirements specification - is going to define how the software works and interface to hardware.
• Testing - Test plan will detail how each requirement is verified, includes test case and the test procedure.
• Safety Analysis - Is going to roughly conform to AS 61508 in order to ensure that I dont design in hazards.