Principles of Communicatons UT-4 (Reviewer Part 3)

Describes signals and systems whose range of frequencies is measured from 0 to a maximum bandwidth or highest signal frequency.

• A. Carrier signal

• B. Baseband signal

• C. Voice grade channel

• D. Signal passband

How much in decibels is 125 W larger than 45 W?

• A. 2.78 dB

• B. 4.44 dB

• C. 27.8 dB

• D. 44.4 dB

Answer explanation

Determine the attenuation in decibels for the attenuator having an input power of 100 mW and an output power of 3.5 mW.

• A. 0.035 dB

• B. -1.46 dB

• C. 14.6 dB

• D. -14.6

Answer explanation

Express 38 dB as a voltage ratio.

• A. 6309

• B. 79.43

• C. 158.87

• D. 63.09

Answer explanation

Express 425 mW as dBm.

• A. 2.63 dBm

• B. 26.3 dBm

• C. -2.63 dBm

• D. -26.3 dBm

Answer explanation

What is the power output of a 3-stage amplifier having to 25 dB, -35 dB and 50 dB respectively, if the input power is 10 mW?

• A. 100 W

• B. 100 mW

• C. 10 W

• D. 10 mW

Answer explanation

The input of a three-stage system is -12 dBm. The power gain of the first stage is 40 dB, for the second stage a loss of 35 dB, and for the third stage, a gain of 25 dB. What is the power output in dBm?

• A. -18 dBm

• B. 18 dBm

• C. 36 dBm

• D. -36 dBm

Answer explanation

The correct symbol for decibel?

• A. DB

• B. dB

• C. db

• D. Db

Which of the following is not an actual amount of power?

• A. dB

• B. dBm

• C. dBw

• D. dBk

What does a power difference of -3 dB mean?

• A. a lose of one third of the power

• B. a lose of one-half of the power

• C. a loss of 3 watts of power

• D. a noise figure value of 3

Answer explanation