Digital Communications

Random Signals

Question 1
Marks : +2 | -2
Pass Ratio : 100%
A random process is called as stationary in strict sense if
Its statistics vary with shift in time origin
Its statistics does not vary with shift in time origin
Its autocorrelation vary with shift in time
Its autocorrelation does not vary with shift in time
Explanation:
A random process is defined to be stationary in a strict sense if its statistics varies with a shift in time origin.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
Standard deviation is ______
Rms value of dc
Rms value or ac
Either ac or dc
Neither dc nor ac
Explanation:
The standard deviation of a random variable gives the rms value of an ac component.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
Which gives the measure of randomness of the random variable?
Mean
Variance
Standard variance
Pdf
Explanation:
Variance gives the randomness of the random variable. It is the difference between the mean square value and square of the mean.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
Random variables give relationship between _____
Two random events
Probability of occurence of two random events
Random event and a real number
Random event and its probability of occurrence
Explanation:
A random variable gives a functional relationship between a random event and a real number.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
The autocorrelation function is maximum at
Origin
Infinity
Origin & Infinity
None of the mentioned
Explanation:
On substituting different values in the formula for autocorrelation function it wil be maximum at the origin.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
The value of the probability density function of random variable is
Positive function
Negative function
Zero
One
Explanation:
The probability density function is always greater than 0. It is a non negative function with the area of 1.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
The distribution function of random variable is
P(X less than or equal to x)
P(X greater than or equal to x)
P(X less than x)
P(X greater than x)
Explanation:
The distribution function of a random variable is the probability that the value taken by the random variable is less than or equal to the real number x.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
For a stationary process, autocorrelation function depends on
Time
Time difference
Does not depend on time
None of the mentioned
Explanation:
Autocorrelation function depends on the time difference between t1 and t2.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
The distribution function of -(infinity) and (infinity) is _____
0 and 1
1 and 0
Both 0
Both 1
Explanation:
F(minus infinity) is 0 and F(infinity) is 1.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
Random process is a function of ______
Random event and time
Random event and frequency
Random event and real number
None of the mentioned
Explanation:
Random process is a function of two variables: a random event and its time of occurrence.