Recent questions tagged analog-communications

Two analog signals $x_{1}(t)$ and $x_{2}(t)(t$ in second $)$, are sampled at a rate $F_{s}=40 \mathrm{~Hz}$, where\[x_{1}(t)=\cos (20 \pi t), t \geq 0, \text { and } x_{2...

Consider the Friis' transmission equation $P_{R}=\left(P_{T} G_{T} G_{R} \lambda^{2}\right) /(4 \pi D)^{2}$, where $P_{R}$ and $P_{T}$ are the received and the transmitte...

Consider a discrete memoryless source with an alphabet of four source symbols. $s(t)$ is a multi-level $(-1,0,+1,+2)$ signal representing a long sequence of random symbol...

A wireless digital transmission scheme is using $16$-QAM over an additive white Gaussian noise channel and a maximum-likelihood receiver. Consider the information bit rat...

Consider a real baseband signal $x(t)=e^{-2 t}$, for $t$ (in seconds) $\geq 0$.If $99 \%$ of energy of $x(t)$ lies within $B \mathrm{~Hz}$, then which of the following op...

Consider a real, narrowband signal $x(t)=A(t) \cos \left[2 \pi f_{c} t+\theta(t)\right]$ where the maximum frequency components of $A(t)$ and $\theta(t)$ are $f_{M}$ and ...

Let $x_{1}(t)=\cos (2 \pi n t)$ and $x_{2}(t)=2 \sin (4 \pi n t)$ represent two sinusoids for a positive integer $n$ and $-\infty < t < \infty$.Which of the following sta...

Consider a frequency-modulated (FM) signal$$f(t)=A_{c} \cos \left(2 \pi f_{c} t+3 \sin \left(2 \pi f_{1} t\right)+4 \sin \left(6 \pi f_{1} t\right)\right)$$where $A_{c}$ ...

Consider a continuous-time finite-energy signal $f(t)$ whose Fourier transform vanishes outside the frequency interval $\left[-\omega_{c}, \omega_{c}\right]$, where $\ome...

A digital communication system transmits through a noiseless bandlimited channel $[-W W]$. The received signal $z(t)$ at the output of the receiving filter is given by $z...

A source transmits symbols from an alphabet of size $16$. The value of maximum achievable entropy (in bits) is $\_\_\_\_\_\_$.

​​​​​A source transmits a symbol $s$, taken from $\{-4,0,4\}$ with equal probability, over an additive white Gaussian noise channel. The received noisy symbol $r$ is give...

Let $m(t)$ be a strictly band-limited signal with bandwidth $B$ and energy $E$. Assuming $\omega_{0}=10 B$, the energy in the $m(t) \cos \omega_{0} t$ is$\frac{E}{4}$$\f...

Let a frequency modulated $\text{(FM)}$ signal$x(t)=A \cos \left(\omega_{c} t+k_{f} \int_{-\infty}^{t} m(\lambda) d \lambda\right)$, where $m(t)$ is a message signal of b...

The capacity of a certain additive white Gaussian noise channel of bandwidth $1 \mathrm{~MHz}$ is $\mathrm{known}$ to be $8 \text{ Mbps}$ when the average transmit power ...

Consider a periodic square wave $f(t)$ with a period of $1$ second such that $f(t)=1$ for $t \in[0,1 / 2)$ and $f(t)=-1$ for $t \in[1 / 2,1)$. It is passed through an ide...

Consider two communication systems $C_{1}$ and $C_{2}$ that use pulse amplitude modulation $\text{(PAM)}$, $P A M_{1}$ and $P A M_{2}$. Let the distance between any two p...

Let $x(t)$ be a signal whose Fourier transform $X(f)$ is zero for $|f|>W$. Using a sampler with sampling frequency $4 W$, which of the following filters can be used to ex...

A rectangular air-filled waveguide has cross section of $4 \mathrm{~cm} \times 10 \mathrm{~cm}$. The minimum frequency which can propagate in the waveguide is$1.5\; \math...

A deterministic signal has the power spectrum given in the figure is, The minimum sampling rate needed to completely represent this signal is$1 \; \mathrm{kHz}$$2 \; \mat...

A communication channel has first-order low pass transfer function. The channel is used to transmit pulses at a symbol rate greater than the half-power frequency of the l...

A parabolic dish antenna has a conical beam $2^{\circ}$ wide, the directivity of the antenna is approximately$20 \; d \mathrm{B}$$30 \; d \mathrm{B}$$40 \; d \mathrm{B}$$...

(1) Wave tiltUnder-water propagation(2) Faraday RotationGround wave propagationSpace wave propagationIonospheric propagation

A block diagram of a system is shown in the figure is draw the spectrum of the output signal with relative aptitudes of the frequencies.

The figure is shows the first stage of a superheterodyne receiver. The desired input signal is at a frequency of $700 \; \mathrm{MHz}$. The local oscillator $\text{(L.O)}...

A dipole antenna has a $\sin \theta$ radiation pattern where the angle $\theta$ is measured from the axis of the dipole. The dipole is vertically located above an ideal g...

The amplitude modulated wave form $s(t)=A_{c}\left[1+K_{a} m(t)\right] \cos \omega_{c} t$ is fed to an ideal envelope detector. The maximum magnitude of $\mathrm{K}_{0} m...

The frequency range for satellite communication is$1 \; \mathrm{kHz}$ to $100\; \mathrm{kHz}$$100 \; \mathrm{kHz}$ to $10 \; \mathrm{kHz}$$10 \; \mathrm{MHz}$ to $30 \; \...