1
GATE ECE 2004
MCQ (Single Correct Answer)
+2
-0.6
The impulse response $$h\left[ n \right]$$ of a linear time invariant system is given as
$$h\left[ n \right] = \left\{ {\matrix{ { - 2\sqrt 2 ,} & {n = 1, - 1} \cr {4\sqrt 2 ,} & {n = 2, - 2} \cr {0,} & {otherwise} \cr } } \right.$$

If the input to the above system is the sequence $${e^{j\pi n/4}},$$ then the output is

A
$$4\sqrt 2 \,{\mkern 1mu} {e^{j\,\pi \,n\,\,/\,4}}$$
B
$$4\sqrt 2 \,{\mkern 1mu} {e^{ - j\,\pi \,n\,/4}}$$
C
$$4{\mkern 1mu} {e^{j\,\pi \,n\,/4}}$$
D
$$ - 4{\mkern 1mu} {e^{j\,\pi \,n\,/4}}$$
2
GATE ECE 2004
MCQ (Single Correct Answer)
+2
-0.6
A causal LTI system is described by the difference equation $$2y\left[ n \right] = ay\left[ {n - 2} \right] - 2x\left[ n \right] + \beta x\left[ {n - 1} \right].$$ The system is stable only if
A
$$\left| \alpha \right| = 2,\,\left| \beta \right| < 2$$
B
$$\left| \alpha \right| > 2,\,\left| \beta \right| > 2$$
C
$$\left| \alpha \right| < 2$$, any value of $$\beta $$
D
$$\left| \beta \right| < 2,$$ any value of $$\alpha $$
3
GATE ECE 2004
MCQ (Single Correct Answer)
+1
-0.3
The impulse response $$h\left[ n \right]$$ of a linear time-invariant system is given by $$h\left[ n \right]$$ $$ = u\left[ {n + 3} \right] + u\left[ {n - 2} \right] - 2\,u\left[ {n - 7} \right],$$ where $$u\left[ n \right]$$ is the unit step sequence. The above system is
A
stable but not causal.
B
stable and causal.
C
causal but unstable.
D
unstable and not causal.
4
GATE ECE 2004
MCQ (Single Correct Answer)
+2
-0.6
Consider the sequence

$$x[n] = [ - \,4 - \,j5,\,\mathop {1 + j2}\limits_ \uparrow ,\,\,4]$$

The conjugate anti-symmetric part of the sequence is

A
$$\left[ {\matrix{ { - 4 - j\,\,2.5} & {j\,2} & {4 - j\,\,2.5} \cr } } \right]$$
B
$$\left[ {\matrix{ { - j\,\,2.5} & 1 & { - j\,\,2.5} \cr } } \right]$$
C
$$\left[ {\matrix{ { - j\,\,5} & {j\,2} & 0 \cr } } \right]$$
D
$$\left[ {\matrix{ { - 4} & 1 & 4 \cr } } \right]$$
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