Test: Electromagnetic & Analog Communications - 2 - Electronics and Communication Engineering (ECE) MCQ

Shortest length of a 42 Ω air line required toproduce a reactance of j73Ω at 1 MHz when line is short circuited is

A transmission line of characteristic impedance 50Ω is terminated by a resistor 100Ω.

Q. The impedance at the voltage maximum position is

A transmission line of characteristic impedance 50Ω is terminated by a resistor 100Ω.

Q. The impedance at the voltage minimum position is

An EM wave travels in free space with the electric field component, E. = 100 e^{i(a866 + a5z)}a_x V/m and ω = 3 x 10⁸ rad/sec. The time average power in the wave is

A 50Ω characteristic impedance line is connected to a load which shows a reflection coefficient of 0.268. If V_in = 15 V, then the net power delivered to the load will be

A TEM wave impinges obliquely on a dielectric-dielectric boundary (,). The angle of incidence for total reflection is

Match List-I (Nature of Polarization) with

List-II (Relationship Between X and Y components) for a propagating wave having cross-section in the XY plane and propagating along Z-direction and select the correct answer:

List-I

A. Linear

B. Left circular

C. Right circular

D. Elliptical

List-II

1. X and Y components are in same phase

2. X and Y components have arbitrary phase difference

3. component leads Y by 90°
    
4. X component lags behind Y by 90°​

Consider the following statements:

1. FDM is possible when the useful bandwidth of the medium exceeds the required bandwidth of signals to be transmitted.
2. Synchronous TDM is not possible when the achievable data rate of the medium exceeds the data rate of digital signals to be transmitted.

A 1 kHz sinusoidal signal is ideally sampled at 1400 samples/sec and the sampled signal is passed through an ideal low-pass filter with cut-off frequency 800 Hz. The output signal has the frequency kHz

In a SSB modulation, the power spectral density of m(t) is given as

where a and W are constants. White Gaussian noise of zero mean and PSD of N₀/2 is added to SSB modulator wave at the receiver input. The (SNR) at the output of the receiver is,

(Where A_c = Carrier signal amplitude)

 An angle modulated signal with carrier frequency ω_c = 2π x 10⁵ is described by the equation Q_Am (t) = 10 cos (ω_c t + 5 sin 3000 t + 10 sin 2000 πt)

The maximum frequency deviation is

A frequency modulated wave is 100% modulated by 10 kHz modulating signal m(t). Then the bandwidth required is

A sinusoid x(t) = A cos2πf_ot is sampled at 5 times the Nyquist rate for 2.5 sec. A total of 250 samples are acquired value of f_s and f_m are given by

The angle-modulated signal with carrier frequency ω_c = 27c x 10⁶ is discribed by the equation

v(t) = 10 cos(ω​_ct + 10sin200t + 20si n400πt) The deviation ratio is

A PCM system uses a uniform quantizer followed by a 7-bit binary encoder. The bit rate of the system is equal to 50 x 10⁶ bps.

Q. The maximum message bandwidth for which the system oeprates satisfactorily, is

The approximate output signal - to ­(quantization) noise ratio when a full - load sinusoidal modulating wave of frequency 1 MHz is applied to the input, is

For an AM wave, the maximum voltage was found to be 10 V and the minimum voltage was found to be 5 V. The modulation index of the wave would be