Electronic Communications A System Approach Comprehensive Exam Script Verified Questions And Solutions Graded Aplus

ELECTRONIC COMMUNICATIONS A SYSTEM
APPROACH COMPREHENSIVE EXAM
SCRIPT VERIFIED QUESTIONS AND
SOLUTIONS GRADED APLUS

●● (+) dB - means?
Answer: Pout > Pin power gain (amplification)


●● (-) dB - means?
Answer: Pout < Pin power loss (attenuation)


●● Pout = Pin means?
Answer: absolute power gain = 1


●● Pout = Pin means?
Answer: dB power gain = 0 dB


●● Pout = Pin means?
Answer: Unity Power Gain


●● dBm

,Answer: Unit of measurement used to indicate the ratio of a power level
with respect to a fixed reference level (1 mW)


●● Decibel relative to 1 milliwatt
Answer: dBm


●● Why 1 mW is the reference of dBM?
Answer: Because it equals the average power produced by a telephone
transmitter


●● (+) dBm
Answer: indicate power levels > 1 mW


●● (-) dBm
Answer: indicate power levels < 1 mW


●● Bel
Answer: Named in honor of Alexander Graham Bell


●● Formula of Decibel
Answer: dB = 10log₁₀ [P1/P2]


●● Formula for power gain in dB

, Answer: Ap(dB) = 10log₁₀ [Pout/Pin]


●● dB power gain in terms of voltage ratio
Answer: Ap(dB) = 10log₁₀[Eₒ²/Rₒ ÷ Eᵢ² / Rᵢ]


●● dB power gain in terms of voltage ratio if Rₒ = Rᵢ
Answer: Ap(dB) = 20log₁₀[Eₒ/Eᵢ]


●● Formula of dBm
Answer: dB = 10log₁₀ [P/0.001 W]


●● Formula of Bel
Answer: Bel = log₁₀ [Pout/Pin]


●● When power levels are given in watts and power gains are given as
absolute values, the output power is determined by simply __________
the input power ________ the power gains
Answer: multiplying, times


●● If a system is composed of several sections and each section has a
gain or loss, the total gain of the entire system in dB can be computed by
______ the gain or loss in each section in __
Answer: adding, dB