Signal Processing - Practice Test

[#171] Consider the following transfer functions: $$eqalign{
& 1.,frac{1}{{jomega + 1}} cr
& 2.,frac{1}{{{{left( {jomega + 1}
ight)}^2}}} cr
& 3.,frac{1}{{left( {jomega + 1}
ight)left( {jomega + 2}
ight)}} cr} $$ The transfer functions which have a non linear phase are:

(A) 1 and 2 only

(B) 1 and 3 only

(C) 2 and 3 only

(D) 1, 2 and 3

Correct Answer

(D) 1, 2 and 3

[#172] Consider an ideal low pass filter. Such a discrete-time system is:

(A) Always realizable physically

(B) Never realizable physically

(C) A non linear system

(D) A linear, causal system

Correct Answer

(B) Never realizable physically

[#173] Let the input be u and the output be y of a system, and the other parameters are real constants. Identify which among the following systems is not a linear system :

(A) $$frac{{{d^3}y}}{{d{t^3}}} + {a_1}frac{{{d^2}y}}{{d{t^2}}} + {a_2}frac{{dy}}{{dt}} + {a_3}y$$ xa0 xa0xa0 $$ = {b_3}u + {b_2}frac{{du}}{{dt}} + {b_1}frac{{{d^2}u}}{{d{t^2}}}$$ xa0 xa0 (with initial rest conditions)

(B) $$yleft( t ight) = intlimits_0^t {{e^{alpha left( {t - au } ight)}}} x08eta uleft( au ight)d au $$

(C) y = au + b, b ≠ 0

(D) y = au

Correct Answer

(C) y = au + b, b ≠ 0

[#174] The z-transform of the time function $$sumlimits_{k = 0}^infty {delta left( {n - K}
ight)} $$ xa0 is

(A) $${z over {z - {a^T}}}$$

(B) $${z over {z + {a^T}}}$$

(C) $${z over {z - {a^{ - T}}}}$$

(D) $${z over {z + {a^{ - T}}}}$$

Correct Answer

(C) $${z over {z - {a^{ - T}}}}$$

[#175] The impulse response and the excitation function of a linear time invariant causal system are shown in figure (a) and (b) respectively. The output of the system at t = 2 sec is equal to

(A) 0

(B) $$frac{1}{2}$$

(C) $$frac{3}{2}$$

(D) 1

Correct Answer

(B) $$frac{1}{2}$$

Signal Processing - Study Mode

[#171] Consider the following transfer functions: $$eqalign{ & 1.,frac{1}{{jomega + 1}} cr & 2.,frac{1}{{{{left( {jomega + 1} ight)}^2}}} cr & 3.,frac{1}{{left( {jomega + 1} ight)left( {jomega + 2} ight)}} cr} $$ The transfer functions which have a non linear phase are:

Correct Answer

[#172] Consider an ideal low pass filter. Such a discrete-time system is:

Correct Answer

[#173] Let the input be u and the output be y of a system, and the other parameters are real constants. Identify which among the following systems is not a linear system :

Correct Answer

[#174] The z-transform of the time function $$sumlimits_{k = 0}^infty {delta left( {n - K} ight)} $$ xa0 is

Correct Answer

[#175] The impulse response and the excitation function of a linear time invariant causal system are shown in figure (a) and (b) respectively. The output of the system at t = 2 sec is equal to

Correct Answer

[#171] Consider the following transfer functions: $$eqalign{
& 1.,frac{1}{{jomega + 1}} cr
& 2.,frac{1}{{{{left( {jomega + 1}
ight)}^2}}} cr
& 3.,frac{1}{{left( {jomega + 1}
ight)left( {jomega + 2}
ight)}} cr} $$ The transfer functions which have a non linear phase are:

[#174] The z-transform of the time function $$sumlimits_{k = 0}^infty {delta left( {n - K}
ight)} $$ xa0 is