Communication System
Random Variable and Random Process
Practice questions from Random Variable and Random Process.
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IncorrectConsider a real-valued random process
where and is a positive integer. Here, for and 0 otherwise. The coefficients are pairwise independent, zero-mean unit variance random variables.
Read the following statements about the random process and choose the correct option.
(i) The mean of the process is independent of time .
(ii) The autocorrelation function is independent of time for all .
(Here, is the expectation operation.)
are independent
Given: constant
(i) is correct
Auto correlation
We can’t comment on ACF of however looking at (as no time data given)
we solve
dependence on is asked, lets fix for all z
as for to :
Clearly is a function
(ii) is false
The random variable takes values in with probabilities and , where . Let denote the entropy of (in bits), parameterized by . Which of the following statements is/are TRUE?
The entropy of a discrete random variable is given as,
The entropy function will thus be:
For maximum entropy,
Thus, at is near to Maximum.
Alternatively,
Hence, option (b) & (c) are correct.
A white Gaussian noise with zero mean and power spectral density , when applied to a first-order RC low pass filter produces an output . At a particular time , the variance of the random variable is _________.
For RC LPF
Suppose and are independent and identically distributed random variables that are distributed uniformly in the interval . The probability that is _________.
(Area of triangle from Z>0)
Let be a random process, where amplitude and phase are independent of each other, and are uniformly distributed in the intervals and , respectively. is fed to an 8 -bit uniform mid-rise type quantizer. Given that the autocorrelation of is , the signal to quantization noise ratio (in , rounded off to two decimal places) at the output of the quantizer is_________.
A random variable , distributed normally as , undergoes the transformation , given in the figure. The form of the probability density function of is (In the options given below, are non-zero constants and is piecewise continuous function)
Given random variables,
X=N(0,1)
is taking discrete set of values and a continuous range of values, so it is mixed random variable. From the given options, density function of ' ' will be.




















































































































