Analog Communication

All Q&A

Explain FM stereo \(\frac{T_x}{R_x}\) system with block schematic diagrams.

20 June, 2022

A stereo FM transmission is a system in which, adequate information is sent to the receiver in order to reproduce the original stereo sound signal. The stereo FM system is made compatible with the usual mono FM system, so that it is possible to receive FM stereo transmission even using mono FM receiver.

Considering a message signal \(e_m=E_mcos\omega_mt\) and carrier signal by \(e_c=E_csin\left(\omega_c+\theta\right)t\), find the expression of the resultant FM wave.

20 June, 2022

The general expression of FM signal is \(S\left(t\right)=E_csin\left(\omega_ct+\theta\right)\) \(S\left(t\right)=E_csin\left(\omega_ct+2\pi k_f\int_{0}^{t}{e_mdt}\right)\)

Explain briefly the VSB-SC modulation

20 June, 2022

The block diagram for generation of VSB signal is shown in Fig. 17. The block diagram consists of incoming message signal \(x\left(t\right)\), carrier signal \(A_ccos2\pi f_ct\), balanced modulator and a Low Pass Filter (LPF).

A modulating signal is given by \(V_m=2sin\left(2\pi\times500t\right)\) amplitude modulates a carrier signal given by \(V_C=10sin2\pi\times{10}^6t\), Determine

Modulation index
Frequency present in the modulated signal
Total transmission power

20 June, 2022

The expression of Amplitude modulated signal is \(S\left(t\right)=\left[10sin2\pi\times{10}^6t+40sin\left(2\pi\times500t\right)sin2\pi\times{10}^6t\right]\) … (1)

Find the carrier and modulating frequency, the modulation index and the maximum deviation of the FM wave presented by the voltage equation \(v=5sin\left(6\times{10}^8t+5sin1000t\right)\). What power will this FM wave dissipate across a 20Ω resistor?

20 June, 2022

Given that \(A_c=5V\), Resistance \(R=20\mathrm{\Omega}\) Carrier frequency \(f_c=\frac{6\times{10}^8}{2\pi}=95.45MHz\)

For a broadcast super heterodyne AM receiver having no RF amplifier, the loaded quality factor Q of the antenna coupling circuit is 100. Now if the intermediate frequency is 455 KHz, then determine the image frequency and its rejection ratio at an incoming frequency of 1 MHz.

27 July, 2024

Given that quality factor Q = 100 The intermediate frequency fi = 455KHz

Write short notes on:

Envelope detector

27 July, 2024

The second method of the non-coherent AM detection is Envelope Detector. In this circuit modulated signal Vin(t) is used as an input signal. The source resistance RS is connected in series with the active non-linear p-n junction diode.