Deck 7: Communications Techniques

Question 1

The ability of an FM receiver to totally mute the receiver audio output except for when a carrier is received is known as:

A) automatic gain control (AGC).
B) automatic noise limiting (ANL)
C) squelch
D) variable sensitivity

Answer 1

C

Question 2

Circuitry used to minimize noise output that occurs when tuning between stations is known as:

A) noise limiters
B) squelch circuitry
C) noise filters
D) all of the above

Answer 2

B

Question 3

What is the purpose of an RF choke?

A) RF chokes is used to isolate the AC circuit from the RF circuitry.
B) Used only at low frequencies.
C) Used only at audio frequencies.
D) RF chokes is used to isolate the DC circuit from the RF circuitry.

Answer 3

D

Question 4

A receiver has a 30 dB noise figure, a 1.5 MHz bandwidth, a 6 dBm third intercept point, and a 3 dB signal-to-noise ratio. Its dynamic range is:

A) 58.7 dB
B) 48.8 dB
C) 56.8 dB
D) 66.7 dB

Question 5

Determine the S/N for a receiver with a 10 MHz bandwidth, a 20 dB noise figure, and a sensitivity of -60 dBm.

A) 10 dB
B) 20 dB
C) 24 dB
D) 14 dB

Question 6

If the above system had a +5dBm third order intercept point, determine its dynamic range

A) 66 dB
B) 31 dB
C) 58 dB
D) 25 dB

Question 7

Which of the following is not considered man-made noise?

A) ignition systems
B) motor systems
C) switching of high current loads
D) resistor noise

Question 8

Determine the sensitivity of a receiver with a 5 MHz bandwidth, 25 dB noise figure, and S/N of 40 dB

A) -84 dBm
B) -20 dBm
C) -42 dBm
D) -70 dBm

Question 9

An AGC that does not provide any gain reduction until some arbitrary signal level is attained and therefore has no gain reduction for weak signals is known as:

A) arbitrary AGC
B) variable AGC
C) delayed AGC
D) auxiliary AGC

Question 10

The S meter is often found in which of the following circuits?

A) RF input amplifiers
B) AGC circuitry
C) audio output
D) IF stage

Question 11

The tuned circuit prior to the mixer is often referred to as the

A) pre-mixer
B) age circuit
C) pre-selector
D) post-processor

Question 12

The input power range over which the receiver or amplifier provides a useful output is known as

A) noise floor
B) dynamic range
C) S/N ratio
D) power range

Question 13

The process of stepping down the RF signal to a first IF frequency and then mixing down again to a second IF signal is known as:

A) down conversion
B) double conversion
C) mixing
D) none of the above

Question 14

Up-conversion is:

A) the process of having the IF frequency in a superheterodyne receiver be higher than the range of RF frequencies being received by the receiver.
B) a technique used to reduce the image frequency problem from occurring in superheterodyne receivers.
C) a superheterodyne receiver design that is feasible due to the availability of VHF crystal filters (30 - 120 MHz) for the IF circuitry.
D) all of the above

Question 15

A transceiver is

A) a transmitter and receiver in a single package
B) a transmitter that transmits digital data signals
C) a transmitter that can be tuned to several bands of frequencies
D) a receiver that receives digital data signals

Question 16

This is an unwanted component of an electronic circuit that is a byproduct of fabrication, component assembly, or both.

A) scrap material
B) parasitic
C) project over runs
D) lead length