All RF Cafe quizzes would make perfect fodder for employment interviews for technicians or engineers
- particularly those who are fresh out of school or are relatively new to the work world. Come to
think of it, they would make equally excellent study material for the same persons who are going to
be interviewed for a job.
Some of these books used in quizzes are available as prizes
in the monthly RF Cafe Giveaway.
Note: Many answers contain passages quoted from the text.
quiz is based on the information presented in Modern Communications Receiver Design and Technology, by Cornell
Published by Artech House. Note: Some of these
books are available as prizes in the monthly
RF Cafe Giveaway
What is the modern version of a "coherer?"
a) Phase locked loop
b) Radio receiver/detector
c) Radio transmitter/exciter
d) Coherent oscillator
What is the difference between a heterodyne (1) and a superheterodyne (2) receiver?
a) (1) uses tubes while (2) uses transistors
b) (1) is direct conversion to 0 Hz while (2) uses an IF
frequency prior to conversion to 0 Hz
c) (1) is low power while (2) is high power
d) (1) uses a DC supply
while (2) uses an AC supply3.
What is an
reflection of a signal
b) The anti-reflection of a signal
c) The frequency generated in the mixer that
duplicates the intended signal
d) The signal on the other side of the LO that will also convert to the same IF
as the intended signal4.
What is a High Probability of Intercept receiver?
a) One that surveys broad frequency ranges in narrow bandwidth samples at high sensitivity
b) A statistical
model of an ideal receiver type
c) The mathematical duel of a Low Probability of Intercept receiver
that uses probability algorithms to extract signals form noise5.
Why would a
double conversion be used instead of a single conversion?
a) Twice the efficiency
b) Half the
c) Avoiding high level intermodulation spurs from the mixer
d) PCB space savings due to two
mixers in one package6.
What is the 1 dB compression point of an electronic
a) The power level at which the device gain is reduced by 1 dB from the linear value
b) The power level at which the device gain is increased by 1 dB from the linear value
c) The 1 dB gain level
d) The pressure where silicon or GaAs breaks from compressive forces7.
one of the main reasons for using a fractional-N phase-locked loop (PLL) synthesizer?
a) Higher power
levels can be tolerated
b) Small frequency steps can be obtained without using multiple PLL loops
c) More readily available parts
d) None of the above8.
What type of diode
usually makes the best RF signal switch?
Why would you use a logarithmic amplifier (log amp)
a) If you
need to convert from linear units to decibels
b) If you are only amplifying very small signals
c) If you are only amplifying very large signals
d) If you must accommodate a large dynamic range at the
input while producing a smaller dynamic range at the output10.
What is(are) the
main difference(s) between an infinite impulse response (IIR) filter and a finite response response (FIR ) filter?
a) An IIR represents "real" analog filters whereas an FIR does not
b) An IIR can be unstable while an FIR
is always stable
c) An IIR filter uses feedback while a FIR filter does not
d) All the above
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