Signals and Systems Flashcards
7 cards from real B CompE Bachelor of Computer Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Signals and Systems flashcards as text
A Linear Time-Invariant (LTI) system must satisfy which two fundamental properties?
Answer: Linearity and time-invariance
LTI systems must obey the superposition principle (linearity) and behave identically regardless of when the input is applied (time-invariance).
The impulse response h(t) of an LTI system is defined as:
Answer: The output when the input is a unit impulse δ(t)
The impulse response is defined as the output of an LTI system when excited by a unit impulse δ(t), and it completely characterizes the system's behavior.
The transfer function H(s) of an LTI system is the Laplace Transform of:
Answer: The impulse response h(t)
H(s) = L{h(t)}, the Laplace Transform of the impulse response, which relates the output to the input in the s-domain via Y(s) = H(s)X(s).
According to the Nyquist sampling theorem, a band-limited signal with maximum frequency f_max must be sampled at a minimum rate of:
Answer: 2 × f_max
The Nyquist criterion requires the sampling frequency f_s ≥ 2 × f_max to prevent aliasing and allow perfect reconstruction of the signal.
Aliasing in a sampled signal occurs when:
Answer: The sampling rate is less than twice the signal bandwidth
Aliasing occurs when f_s < 2 × f_max (below the Nyquist rate), causing high-frequency components to fold back and appear as spurious low-frequency components.
A system is BIBO stable if and only if:
Answer: Its impulse response is absolutely integrable (∫|h(t)|dt < ∞)
BIBO (Bounded-Input Bounded-Output) stability requires that ∫|h(t)|dt < ∞, guaranteeing that every bounded input produces a bounded output.
A causal system is one in which the output depends only on:
Answer: Past and present values of the input
A causal system can only depend on current and past inputs (not future inputs), making it physically realizable in real-time applications.
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