The device which superimposes information onto a high frequency signal for trans
ID: 2083274 • Letter: T
Question
The device which superimposes information onto a high frequency signal for transmission is called: i. a demodulator ii. the carrier iii. a modulator iv. the intelligence b) The two types of angle modulation are: i. amplitude and frequency modulation ii. phase and frequency modulation iii. pulse and frequency modulation iv. phase and amplitude modulation c) In an FM modulator, the amplitude of the intelligence signal determines the: i. rate of the carrier frequency deviation. ii. power level of the FM signal. iii. phase angle of the carrier frequency component. iv. amount of carrier frequency deviation. d) Overmodulation: i. results when the modulation index exceeds unity ii. is undesirable because it produces sideband splatter iii. causes the AM signal to become distorted so that the receiver cannot produce clean replica of the original intelligence signal iv. all of the above e) Which of the following is an advantage of transmitting in a digital format? i. less sensitive to noise ii. less crosstalk iii. lower distortion levels iv. all of the aboveExplanation / Answer
a) answer (iii)
modulater (signal + carrior).
intelegence signal is the input signal
demodulater is remove the carrior from the signal
carrior is the high frequency signal .
b) answer (ii)
Angle modualations are phase modulation and frequency modulation.
amplitude modulation dependes on amplitude of the signal and pulse modulation is depends varied in some respect, such as width or amplitude, to represent the amplitude of a signal
c) answer (iv)
modulation where the angle of a sine-wave carrier is varied as a function of the intelligence amplitude.
Two ways to do it: –
Phase Modulation (PM) – amount of phase change on angle of carrier is proportional to intelligence amplitude – Frequency Modulation (FM) – frequency change on angle of carrier is proportional to intelligence amplitude
d)answer(iv)
-the modulating signal exceeds the value necessary to produce 100% modulation of the carrier.
-in AM (> 100% modulation depth), "overmodulation", the original sine wave can no longer be detected with an envelope detector.
-overmodulation also produces side band splatters.
e)answer (iv)
digital formate is more secure then anlog data transmission because it less sensitive to noise ,crosstalk and it also lower distrotion in transmission.