Test: Digital Communications - 2 - Electronics and Communication Engineering (ECE) MCQ

In a Binary digital communication system, the threshold voltage of comparator is 'x' volts and voltage at input of comparator is uniformly distributed in the range of x-0.5 to x+0.25 when '0' is transmitted and it is in the range x-0.25 to x+0.5 when bit '1' is transmitted, the average probability of error in the system is_____________

If probability of error of PSK signal is 'x', then what will be probability of error of FSK and ASK signal. (Assume x =

If input to matched filter is s(t) = f(t)+ 2f (t)δ(t - 0.5) + f(t - 2.5)*8δ(t+ 0.5)

where f(t) is shown below, then determine the impulse response of matched filter h(t) ; 2 5 ≤ t < 3

(Note: δ is Delta function and * is convolution operator)

Match the following:

Modulation             Type of signaling format to be

technique                     used for modulation

1. ASK               (a)       ON-OFF

2. PSK                (b)       Non return to zero

3. FSK                (c)       Return to zero

4. DPSK

5. QPSK

Consider a BSC with cross-over probability of error P. Suppose that R is the number of bits in a source code word that represents one of 2^R possible levels at the output of quantizer. If R = 5, P = 0.01, then the probability of having 5 or less bits in error in a code word is_____________  

A black and white television picture may be viewed as consisting of approximately 3x10⁵ elements, each of which may occur one of 10 distinct brightness levels with equal probability. Transmission rate is 30 picture frames/ second and SNR is 30 dB. Then the minimum bandwidth required to support the transmission of the resulting video signal is   MHz

A random variable X has 

Q. The value of constant K is

A random variable X has 

Q. The value of P(4 < x 5 ≤ 8) is

A telegraphic source has two symbols dot and dash. The dot duration is 0.2sec. The dash is twice as long as the dot and half as probable.

Q. The entropy of source is

A telegraphic source has two symbols dot and dash. The dot duration is 0.2sec. The dash is twice as long as the dot and half as probable.

Q. The information rate is

Consider a cascaded block of an LTI system
 

The impulse response of S_1. is h_1. t = δ t -2 The impulse response of 5₂ is h₂ t = t.e^-ru t

The input x(t) is wide sense stationary random process with R_xx 0 = 3 and variance = 1

Q. The mean of the random process w(t) is

Consider a cascaded block of an LTI system
 

The impulse response of S_1. is h_1. t = δ t -2 The impulse response of 5₂ is h₂ t = t.e^-ru t

The input x(t) is wide sense stationary random process with R_xx 0 = 3 and variance = 1

Q. If w(t) is input to system 5₂, then mean of process Y(t) will be

CDF of a random variable x is given below.

Q. E[x] is

CDF of a random variable x is given below.

Q. Variance is

Consider a discrete memory less source X with two symbols x1 and x2 and P (x_i) = 0.9, P (x₂) = 0.1. These symbols are encoded as below.

Q. Find the source efficiency η

Consider a discrete memory less source X with two symbols x1 and x2 and P (x_i) = 0.9, P (x₂) = 0.1. These symbols are encoded as below.

Q. Find the redundancy γ

The input to a linear delta modulator having a step-size D = 0.628 is a sine wave with frequency f_m and peak amplitude E_m. If the sampling frequency f_s = 40kHz, the combination of the sine-wave frequency and peak amp, where slope overload will take place is

     E_m                   f_in                                         E_m                    f_in

(a)           0.3V               8kHz                            (b)       1.5V                 4kHz

(c)          1.5V               2kHz                            (d)       3.0V                 1kHz