IndiaBix - Communications

a

A certain fiber-optic cable has the following characteristics: n1 = 1.82 and n2 = 1.73. What is the value of θc? A. 71.90º B. 0.95º C. 18.1º D. 1.81º

d

A phase-locked loop (PLL) is a feedback circuit consisting of a A. phase detector. B. low-pass filter. C. VCO. D. all of the above

a

Amplitude modulation is a _____ process. A. multiplication B. division C. sum/difference

a

An AM demodulator can be implemented with a linear multiplier followed by a ________ filter. A. low-pass B. high-pass C. band-pass D. band-stop

c

For a four-quadrant linear multiplier, what is the output voltage, given input voltages of Vx = +2 V and Vy = -10 V? A. +2 V B. +1 V C. -2 V D. -1 V

a

If a 1 MHz carrier is amplitude modulated with a 5 kHz audio signal, the upper-side frequency is ________ kHz. A. 1005 B. 1000 C. 995 D. none of the above

a

In AM, the carrier is changed by a modulating signal. What parameter of the carrier is changed? A. amplitude B. frequency C. pulse width D. phase

a

In order for a light ray to propagate along a fiber-optic cable, what must the relationship be between the angle of incidence and the critical angle? A. θi > θc B. θi < θc C. θi = θc D. none of the above

d

Light may be propagated along a fiber -optic cable in which of the following modes? A. multimode step index B. single-mode step index C. multimode graded index D. all of the above

b

The intermediate frequency in a standard AM receiver is A. 455 Hz. B. 455 kHz. C. 4.55 MHz. D. none of the above

b

The output spectrum of a ________ modulator includes upper-side and lower-side frequencies and the carrier frequency. A. balanced B. standard amplitude C. none of the above

b

What does VCO stand for? A. Visually-Controlled Organization B. Voltage-Controlled Oscillator C. Voltage-Centered Oscilloscope