Lesson 1/Learning Event 1
LESSON 1
COMMUNICATION CIRCUIT QUALITY
TASK:
Describe the characteristics that affect signal quality,
causes and effects of signal quality, and principles of
measuring signal distortion of VF circuits IAW Defense
communications Agency (DCA) standards.
CONDITIONS:
Given information about VF circuit characteristics, signal
quality, principles of measuring signal distortion and VF
circuit standards established by DCA.
STANDARDS:
Demonstrate competency of the task skills and knowledge by
responding to the multiple-choice practice exercise; select
the ONE answer that BEST completes the statement or answers
the question, covering communication circuit quality.
(This objective supports Tasks 113-616-3018, Test Circuit for Impulse Noise,
TD-8; 113-616-3020, Test Circuit for Composite Data Transmission Level, TD-
10; 113-616-3062, Determine Test Tone Level; 113-616-3075, Test Circuit for
Basic Noise,-TD-6; 113-616-3031, Perform In-Service QC Tests.)
REFERENCES:
DCAC 310-70-1, Volumes I, II, and III.
DCAC 310-70-1, Volume II, Supplement 1 and 2.
DCAC 300-175-9
MIL-STD-198-101
Learning Event 1: QUALITY OF COMMUNICATION.
Electrical communication is carried by wire or radio, or by a
combination of the two.
The quality of communication by either wire or
radio is affected by noise, interference, and distortion. When none of the
three are present, the circuit quality and the signals are said to be
perfect.
Although no communication circuit has perfect quality, every
attempt is made by communicators to reduce the effect of noise,
interference, and distortion.
a. Noise. There are two forms of noise: natural and manmade. Natural
noise results from atmospheric conditions, while manmade results from
electrical appliances and devices.
b. Interference.
Interference is the disturbance caused within a
signal by extraneous signals. Interference in cables usually results from
electromagnetic or electrostatic induction between wire pairs. Interference
between radio stations is caused by careless operators or unstable radio
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