PRINCIPLE OF COMM prelims

communication

the exchange of any type of message between a sender and a receiver.

communication systems

refers to communication that uses a transmitter, channel & receiever

transmitter

this converts a message into an electric form suitable for transmission

ex: mic, tv

communication channel

this is the medium where an electronic signal is sent from one point to another

electric conductor

a material that conducts electricity and allows the flow of charge such as metals & alloys. channels can be simple as a pair of wires that carry a voice signal from a mic to a headset

optical media

can b a fiber-optic cable or light pipe that carries the message on a light wave. these r used today to carry long-distance calls and all internet comms

free space

the resulting system is known as radio when free apace is the channel. radio is the term applied to any wireless communication from point to point

passive sonar

this listens for underwater sounds with sensitive hydrophones

active sonars

use an echo-reflecting technique for determining how far away objects underwater are and in what direction theyre moving

receiver

these r electronic components and circuits that accept transmitted messages from the channel and translat them back which humans understand

amplifiers

produce and increased version of input signals

oscillators

produce a continuous, repeated and alternating waveform without input

mixers

combine 2 or more signals into 1-2 output signals

tuned circuits

also called resonant circuits, combine and inductor & capacitor to make a circuit responsive to a frequency

filters

a circuit capable of amplifying specific frequencies while attenuating others

block diagram of communication systems

simplex communication

duplex communication

analog signal

sine wave

digital signal

telegraph / morse code

continuous-wave (CW) code

binary codes