GATE EC Communications questions

A $\text{PLL}$ can be used to demodulate

For a narrow band noise with Gaussian Gradrature components, the probability density function of its envelope will be

The image (second) channel selectivity of a super beterodync communication receiver is determined by

For a short wave radio link between two stations via the ionosphere, the ratio of the maximum usable frequency to the critical frequency

Medium wave radio signals may be received at far off distances at night because

$v(t)=5[\cos (106 \; \pi t)-\sin (103 \; \pi t) \times \sin (106 \; \pi t)$ represents

Which of the following demodulator(s) can be used for demodulating the signal $x(t)=5(1+2 \cos 2000 \pi t) \cos 2000 \pi t .$

A pulse train with a frequency of $1 \; \mathrm{MHz}$ is counted using a modulo $1024$ ripple-counter built with $\text{JK}$ flip flops. For proper operation of the counter, the maximum permissible propagation delay per flip flop stage is $\dots n \mathrm{Sec}$.

Source encoding in a data communication system is done is order to

Coherent demodulation of $\text{FSK}$ signal can be effected using

The bit stream $01001$ is differentially encoded using $\text{'Delay and Ex OR'}$ scheme for $\text{DPSK}$ transmission. Assuming the reference bit as a $'1'$ and assigning phases of $'0'$ and $\pi$ for $1$’s and $0$’s respectively, in the encoded sequence, the transmitted phase sequence becomes

The maximum power efficiency of an $\text{AM}$ modulator is