LESSON 4
RADIO COMMUNICATION
SCOPE........................................................................... Communication without wires; significance of
frequencies; principles of radio communication; AM and
FM operating principles; introduction to single sideband.
CREDIT HOURS ........................................................... 1
TEXT ASSIGNMENT ................................................... IT 11-180-8;
Attached Memorandum, para 4-1 thru 4-4
MATERIALS REQUIRED............................................. None
SUGGESTIONS............................................................. Review frames 41 thru 49 in IT 11-180-8, then study the
Attached Memorandum.
LESSON OBJECTIVES
When you have completed this lesson, you should:
1. Know that a radio communication system includes a radio transmitter, radio receiver, and connecting radio
waves.
2. Know that the primary difference between ac waves is their frequencies.
3. Know that the characteristics of a radio receiver must be compatible with the type of signal being received.
4. Be able to calculate wavelength of a radio wave when frequency is known.
5. Be able to identify frequency bands of the spectrum by frequency ranges.
ATTACHED MEMORANDUM
4-1. COMPONENTS Of A RADIO COMMUNICATION SYSTEM
a. General. As you have learned, any basic communication system consists of three parts: a source of
energy, a transmission path for that energy, and a receiver capable of utilizing the energy. To be useful, the
communication system must be capable of transmitting some form of intelligence. Imagine that someone is
shining a flashlight beam across a darkened room toward you. You are aware that a light is shining, and perceive
the light's location, but that is about all. If, however, the person holding the flashlight turns it on and off in a
prearranged code, then his pattern of intelligence is being transmitted; a useful communication system is thereby
established. We might say that the intelligence is modulating the energy source.
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