Introduction to Communication Systems

In analog transmission waveform shape itself carries the needed info.

• Yes receiver should detect the waveform correctly

• No receiver already know the transmitted signal waveform so detection of the waveform not required.

Which relation is the worst in terms of efficient bandwidth usage if the channel capacity is (C) and data rate is R

• R < C

• R > C

• R=C

• C >> R

If two vector is orthogonal then their similarity is zero.

• True

• False

If the correlation coefficient is 1 for two signal pair x and g? What you can say about these signals? You can choose more than one answer?

• They are certainly the same signals

• They are aligned vector in vector analogy but they might be different signals.

• Autocorrelation of each signal should be known to evaluate the similarity

• They are orgthogonal signals

An AM transmitter generates 100 watts with 0% modulation. How much power will it generate with 20% modulation?

• To answer we need to know carrier amplitude

• 102 watts

• 100 watts

• 20 watts

You look at an AM signal with an oscilloscope and see that the maximum Vpp is 100 volts and the minimum Vpp is 25 volts. What is the modulation index?

• 0.6

• 0.5

• 1/4

• can not be calculated

Increasing the bandwidth of channel by twice the capacity will increase with same rate.

• Yes

• No

In AM, total sideband power is always ------------- the carrier power.

• equal to

• half of

• higher than

• less than

Power spectral density of the white noise is flat independent of frequencies.

• Yes

• No

• It depends on in phase and quadrature components not frequencies

• It depends on channel bandwidth in which noise is defined together with frequencies

________ is a type of transmission impairment in which the signal loses strength due to the different propagation speeds of each frequency that makes up the signal.

• Attenuation

• Distortion

• Noise

• Desibel