Requirements may have the following characteristics:
An expectation of functions and capabilities (e.g., non-functional
requirements), or one of its interfaces from a black-box perspective that is verifiable, does not imply a design or implementation decision, is
unambiguous, and does not introduce contradictions to other
requirements. A requirements statement that implies, or represents, a design or
implementation decision is called “Design Constraint”. Examples for requirements aspects at the system level are thermal
characteristics such as
heat dissipation dimensions weight materials
Examples of aspects related to requirements about system interfaces
are
connectors cables housing
Examples for requirements at the hardware level are
lifetime and mission profile, lifetime robustness maximum price storage and transportation requirements functional behavior of analog or digital circuits and logic quiescent current, voltage impulse responsiveness to crank, startstop, drop-out, load dump temperature, maximum hardware heat dissipation power consumption depending on the operating state such as
sleep-mode, start-up, reset conditions frequencies, modulation, signal delays, filters, control loops power-up and power-down sequences, accuracy and precision of
signal acquisition or signal processing time computing resources such as memory space and CPU clock
tolerances maximum abrasive wear and shearing forces for e.g., pins or
soldering joints requirements resulting from lessons learned safety related requirements derived from the technical safety
concept
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