04-04-2013, 04:25 PM
EC 1302- Digital Signal Processing - 2 MARKS & QUESTION- ANSWERS
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1. What is a continuous and discrete time signal?
Ans:
Continuous time signal: A signal x(t) is said to be continuous if it is defined for all time t.
Continuous time signal arise naturally when a physical waveform such as acoustics wave
or light wave is converted into a electrical signal. This is effected by means of
transducer.(e.g.) microphone, photocell.
Discrete time signal: A discrete time signal is defined only at discrete instants of time.
The independent variable has discrete values only, which are uniformly spaced. A
discrete time signal is often derived from the continuous time signal by sampling it at a
uniform rate.
2. Give the classification of signals?
Ans:
Continuous-time and discrete time signals
Even and odd signals
Periodic signals and non-periodic signals
Deterministic signal and Random signal
Energy and Power signal
3. What are the types of systems?
Ans:
Continuous time and discrete time systems
Linear and Non-linear systems
Causal and Non-causal systems
Static and Dynamic systems
Time varying and time in-varying systems
Distributive parameters and Lumped parameters systems
Stable and Un-stable systems.
4. What are even and odd signals?
Ans:
Even signal: continuous time signal x(t) is said to be even if it satisfies the condition
x(t)=x(-t) for all values of t.
Odd signal: he signal x(t) is said to be odd if it satisfies the condition x(-t)=-x(t) for all t.
In other words even signal is symmetric about the time origin or the vertical axis, but odd
signals are anti-symmetric about the vertical axis.
5. What are deterministic and random signals?
Ans:
Deterministic Signal: deterministic signal is a signal about which there is no certainty
with respect to its value at any time. Accordingly we find that deterministic signals may
be modeled as completely specified functions of time.
Random signal: random signal is a signal about which there is uncertainty before its
actual occurrence. Such signal may be viewed as group of signals with each signal in the
ensemble having different wave forms
.(e.g.) The noise developed in a television or radio amplifier is an example for random
signal.
6. What are energy and power signal?
Ans:
Energy signal: signal is referred as an energy signal, if and only if the total energy of the
signal satisfies the condition 0<E<. The total energy of the continuous time signal x(t)
is given as
E=limTx2 (t)dt, integration limit from –T/2 to +T/2
Power signal: signal is said to be powered signal if it satisfies the condition 0<P<.
The average power of a continuous time signal is given by
P=limT1/Tx2(t)dt, integration limit is from-T/2 to +T/2.
7. What are the operations performed on a signal?
Ans:
Operations performed on dependent variables:
Amplitude scaling: y (t) =cx (t), where c is the scaling factor, x(t) is the continuous time
signal.