Recent questions tagged communication-and-optical-instrumentation

An analog speech signal contains signals from $200$ $\mathrm{Hz}$ to $2400$ $\mathrm{Hz}$. It is sampled at $6$ $\mathrm{kHz}$ and quantized with $512$ levels for pulse c...

The slope efficiency of a laser diode is $0.5 \mathrm{~W} / \mathrm{A}$, and the output optical power at a current of $100$ $\mathrm{mA}$ is $30$ $\mathrm{mW}$. Assuming ...

An amplitude modulated voltage signal $x(t)$ drives a load of $1 \Omega$.$$x(t)=K \cos (300 \pi \: t)+L \cos (240 \pi \: t)+L \cos (360 \pi \: t) .$$If the efficiency is ...

For a fiber Bragg grating-based sensor, the shift in the Bragg wavelength gives information about the value of the measurand. For a Bragg wavelength of $1550$ $\mathrm{nm...

A photodiode has a responsivity $0.8 \mathrm{~A} / \mathrm{W}$. If the input optical power to the photodiode is $2$ $\mathrm{mW}$, the power delivered to a $50 \: \Omega$...

Let $f(t)$ and $g(t)$ represent continuous-time real-valued signals. If $h(t)$ denotes cross-correlation between $f(t)$ and $g(-t)$, its continuous-time Fourier transform...

A schematic of a Michelson interferometer, used for the measurement of refractive index of gas, is shown in the figure. The transparent chamber is filled with a gas of re...

​Consider an ultrasonic measurement system shown in the figure. The ultrasonic transmitter $(T)$ sends a continuous wave signal $x(t)=\cos \left(2 \pi f_{1} t\right)$ vol...

Which of the following flow meters offers the lowest resistance to the flow? Turbine flow meter Orifice flow meter* Venturi meter Electromagnetic flow meter

In a $p-i-n$ photodiode, a pulse of light containing $8 \times 10^{12}$ incident photons at wavelength $\lambda_0=1.55~ \mu \mathrm{m}$ gives rise to an average $4 \times...

A silica-glass fiber has a core refractive index of $1.47$ and a cladding refractive index of $1.44.$ If the cladding is completely stripped out and the core is dipped in...

A sinusoidal carrier wave with amplitude $A_{c}$ and frequency $f_{c}$ is amplitude modulated with a message signal $m(t)$ having frequency $0 < f_{m} \ll f_{c}$ to gener...

A signal $x(t)$ is band-limited between $100 \; \text{Hz}$ and $200 \; \text{Hz}.$A signal $y(t)$ is related to $x(t)$ as follows:$$y(t) = x (2t – 5)$$The statement that ...

The figure shows a Chromel-Alumel thermocouple, where the junction $A$ is held at temperature $T_{A},$ and a thermal emf $E_{1}$ is measured using an ideal voltmeter betw...

Consider $24$ voice signals being transmitted without latency using time-division multiplexing. If each signal is sampled at $12 \; \text{kHz}$ and represented by an $8$-...

A photodiode is made of a semiconductor with a bandgap of $1.42 \; \text{eV}.$ Given that Plank’s constant is $6.626 \times 10^{-34} \; \text{Js,}$ the speed of light in ...

Monochromatic light of wavelength $532 \; \text{nm}$ is used to measure the absorption coefficient of a material in a $\text{UV}$-Visible Spectrophotometer. The measured ...

An amplitude modulation $\text{(AM)}$ scheme uses tone modulation, with modulation index of $0.6$. The power efficiency of the $\text{AM}$ scheme is ______________ $\%$ (...

When the movable arm of a Michelson interferometer in vacuum $(n=1)$ is moved by $325\: \mu m$ , the number of fringe crossings is $1000$. The wavelength of the laser use...

A laser pulse is sent from ground level to the bottom of a concrete water tank at normal incidence. The tank is filled with water up to $\text{2 m}$ below the ground leve...

A signal having a bandwidth of $\text{5 MHz}$ is transmitted using the Pulse code modulation $\text{(PCM)}$ scheme as follows. The signal is sampled at a rate of $50\%$ a...

In the figure shown, a large multimode fiber with $n_{\text{core}}=1.5$ and $n_{\text{clad}}=1.2$ is used for sensing. A portion with the cladding removed passes through ...

A laser beam of 10 mm beam diameter is focused onto an optical fiber using a thin biconvex lens as shown in the figure. The refractive index of the lens is $1.5$. The ref...

As shown in the figure, a slab of finite thickness $t$ with refractive index $n_2=1.5$, has air $(n_1=1)$ above and below it. Light of free space wavelength $600 nm$ is i...

The mutual inductances between the primary coil and the secondary coils of linear variable differential transformer (LVDT) shown in the figure are $M_1$ and $M_2$. Assume...

Quantum efficiency of a photodiode (ratio between the number of liberated electrons and the number of incident photons) is $0.75$ at $830\;nm$. Given Planck’s constant $h...

In a sinusoidal amplitude modulation scheme (with carrier) the modulated signal is given by $A_m(t)=100\cos(\omega_ct) +50\cos(\omega_mt)\cos(\omega_ct)$, where $\omega_c...

An angle modulated signal with carrier frequency $\omega_c=2\pi\times10^6\;rad/s$ is given by $\varphi_m(t)=\cos(\omega_ct+5\sin(1000\pi t)+10\sin(2000\pi t))$. The maxim...

The probability that a communication system will have high fidelity is $0.81$. The probability that the system will have both high fidelity and high selectivity is $0.18$...

In a single-mode optical fiber, the zero-dispersion wavelength refers to the wavelength at which the material dispersion is zero.waveguide dispersion is zero.sum of mater...

A signal cos(2$\pi$f${_m}$t) modulates a carrier cos(2$\pi$f${_c}$t) using the double -sideband-with-carrier (DSDWC) scheme to yield a modulated signal cos(2$\pi$f${_c}$t...

A 100 W light source emits uniformly in all directions. A photodetector having a circular active area whose diameter is 2 cm is placed 1 m away from the source, normal to...

A pulsed laser emits rectangular pulses of width 1 nanosecond at a repetition rate of 1kHz. If the average power output is 1 mW, the average power over a single pulse dur...

The output of a continuous-time system y(t) is related to its input x(t) as y(t) = x(t) + $\frac{1}{2}$x(t-1). If the Fourier transforms of x(t) and y(t) are x($\omega$) ...

A signal x(t) has a bandwidth 2B about a carrier frequency of f${_c}$ = 2 GHz as shown in Figure (a) below. In order to demodulate this signal, it is first mixed (multipl...

Consider a Michelson interferometer as shown in the figure below. When the wavelength of the laser light source is switched from 400 nanometer to 500 nanometer, it is obs...

The signal $m(t)=cos(\omega_mt)$ is $SSB$ (single side-band) modulated with a carrier $\cos(\omega_ct)$ to get $s(t)$. The signal obtained by passing $s(t)$ through an id...

Let $s(t)=rect\left(\frac{t-3}{3}\right)$ be a signal passed through an $AWGN$ (additive white Gaussian noise) channel with noise power spectral density $(PSD)$ $\frac{N_...

The photo diode in the figure below has an active sensing area of $10 \;mm^2,$ a sensitivity of $0.5\;A/W$ and a dark current of $1\; \mu A$. The $i-to-v$ converter has a...

The signal $m(t)=\frac{\sin(100\;\pi t)}{100\; \pi t}$ is frequency modulated $(FM)$ with an $FM$ Modulator of frequency deviation constant of $30\;kHz/V$. Using Carson’s...