Communications ...

For an AM system with modulation index μ_a = 0.6, the ratio of SSB signal power to the AM signal power is _________. (Correct up to three decimal places)

An angle modulated signal s(t) is given as

s(t) = A_c cos [ω_ct + 2 cos 60 πt + 5 cos 40πt]

where ω_c is the carrier frequency.

Let x and y be two random variables. If x takes two values {+1, -1} and y is defined as y = -x further if E[x] = 0 and var[x] = 1. Then the variance of x + y is _________.

A communication channel of bandwidth 75 kHz is required to transmit binary data at a rate of 0.1 Mb/s using raised-cosine pulses. The roll-off factor α will be ______.

For the Hamming block code, if ‘n’ be total word length of the block and ‘k’ be the number of information bit, then an allowable code of this (n, k) family of Hamming code is

In a certain course, letter grades A, B, C, D, and E are given with equal numbers/probability. When the instructor tells a student that his grade is not E, how much information in bits did the student receive?

Suppose Y is a random variable representing the number of successes in 5 independent Bernoulli trials with success probability p = 0.6. What is the probability that Y equals 3?

Consider a low-pass random process with a white-noise power spectral density  as shown in fig.

The auto correlation function R_x(τ) is

The modulating index of an AM-signal is reduced from 0.8 to 0.5. The ratio of the total power in the new modulated signal to that of the original signal will nearly be

A random process consists of three samples function X(t, s₁) = 2, X(t, s₂) = 2cos t₁ and X(t, s₃) = 3sint - each occurring with equal probability. The process is

A random variable X is uniformly distributed on the interval (-5, 15).

The auto correlation function of a stationary ergodic random process is shown in fig.

The mean value E[X(t)] is

An angle modulated signal is given as x(t) = 100 cos (2πf_ct + 4 sin 2πf_m t) where f_c = 1000 MHz and f_m = 1000 Hz.

The auto correlation function of a stationary ergodic random process is shown in fig.

The variance σ_x² is

A music signal band-limited to 15 kHz is sampled at 45 kHz samples/sec and it sent using 8 bit PCM. SNR of this system was found to be 10 dB. If the sampling rate is reduced to 35 × 10³ samples/sec. The improvement in SNR assuming bit rate does not exceed previous case is _____ dB.

A stationary zero mean random process X(t) is ergodic has average power of 24 W and has no periodic component. The valid auto correlation function is

A stationary random process X(t) is applied to the input of a system for which  If E[X(t)] = 2, the mean value of the system's response Y(t) is

White noise with power density N₀/2 is applied to a low pass network for which |H(0)| = 2. It has a noise bandwidth of 2 MHz. If the average output noise power is 0.1 W in a 1 - Ω( resistor, the value of N₀ is

The two-level semi-random binary process is defined by X(t) = A or – A where (n – 1) T < t < nT and the levels A and -A occur with equal probability. T is a positive and n = 0, ± 1, ± 2.

Which of the following statements is/are correct?

A Binary PAM employs rectangular pulses of duration T_b and amplitudes ±A to transmit digital data at rate of R_b = 10⁵ bits/sec. If the power spectral density of the additive Gaussian noise is \(\frac{{{N_o}}}{2}\) where N_o = 10^-2 W/Hz. The value of pulse Amplitude to achieve probability of error 10^-6 is

An ideal filter with a mid-band power gain of 8 and bandwidth of 4 rad/s has noise X(t) at its input with power spectrum  The noise power at the network's output is (F(2) = 0.9773)

White noise with power density N₀/2 = 6 μW/Hz is applied to an ideal filter of gain 1 and bandwidth W rad/s. If the output's average noise power is 15 watts, the bandwidth W is

Digital information is to be transmitted by carrier modulation through an additive Gaussian noise channel with a bandwidth of 100 kHz and N₀ = 10^-10 W/Hz. (Assume that \(\frac{sinx}{x}\) (sinc) pulse waveform is used)

A communication system using Binary phase shift keying uses signals 5cos (10⁶t) for bit ‘1’ and -5cos (10⁶t) for bit ‘0’. If two-sided power spectral density of noise is 0.125 × 10^-7 W/Hz

The bit error rate of the communication system for data rate of 20 mbps is

\((Assume\;erfc{\left( z \right) \simeq \frac{{{e^{ - {z^2}}}}}{{\sqrt {\pi z}}}})\)

In a transmission of a picture there are 2.25 x 10⁶ picture elements per frame. For good reproduction 12 brightness levels are necessary. Assuming all these levels to be equiprobable, the minimum channel bandwidth required to transmit one picture in every three minutes for a signal to noise ratio of 30 decibels is ________ kHz