Voice communication - EngineersGarage

workablejeansMobile - Wireless

Nov 21, 2013 (3 years and 10 months ago)

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Contents


Voice communication


About our project


Power line communication


Difference between a wired and wireless data
communication


Block diagram


Circuit diagram


Interference


Demodulation & modulation


Conclusion




Voice communication


There are two types of communication system


Wired communication
-
For wired
communication we need pairs of copper wires
or a solid medium to transmit the signal.


Wireless communication=signals are
transmitted through RF transmission.


About our project


Here in this project we will use wired type of
communication. But we will not install separate
copper wires for transmitting voice signal; we will
use the existing electrical line of 220 volts/50 Hz
for transmitting these voice signals.


We can use the same electric line to transmit the
voice or data. We just have to connect our
instrument at any 3 pin socket of electric fitting.


What is power line communication
???


It is a system for carrying data on a
conductor.


It uses the existing power lines to
transmit data from one device to
another.


This makes power line communication
one of the best means for networking.

How communication over electrical line operates


It operates by impressing a modulated carrier
signal on the wiring system.


Data rates over a line communication system
vary widely.



Difference between a wired and wireless data
communication


Wired

networks

are

easy

to

set

up

where

wireless

networks

are

comparatively

difficult

to

set

up,

maintain,

and

troubleshoot
.


Wired

networks

have

better

transmission

speeds

than

wireless

ones
.


In

a

wired

network,

a

user

does

not

have

to

share

space

with

other

users

and

thus

gets

dedicated

speeds

while

in

wireless

networks

Block diagram




MIC as transducer to
convert audio into
electricity


Signal conditioning



Audio amplifier



Speaker



Audio Amplifier



Signal

conditioning


Coupling to power
line


Coupling

to

power

line

Microphone


A
microphone

is an acoustic
-
to
-
electric transducer or
sensor that converts sound into an electrical system.


Microphones are used in many applications such as
telephones
,
tape
recorders
,h
earing

aids
,
motion
picture

production, live and recorded
audio
engineering
,
FRS radios
,
megaphones
, in
radio

and
television

broadcasting and in computers for
recording voice,
speech recognition
,
VoIP
, and for
non
-
acoustic purposes such as ultrasonic checking or
knock sensors
.

Audio amplifier

Signal Conditioning


It is a Processing the form or mode of a signal so as
to make it intelligible to or compatible with a given
device, such as a data transmission line, including
such manipulation as pulse shaping, pulse clipping,
digitizing, and linear zing.



Signal conditioning can include
amplification
,
filtering
, converting, range matching, isolation and
any other processes required to make sensor output
suitable for processing after conditioning




Coupling to power line


Before going in emission there are still two circuits to
tune, the coupling between the transmitter and the
line, and the coupling between the line and the
antenna
.


This coupling circuit is mainly used when the feed
line displays a high impedance like an open
-
wire and
is usually not necessary when a coaxial line is used
since the SWR is low enough to be adjusted by the
transmitter antenna tuner.

Speaker

A device that converts analog audio signals into the
equivalent air vibrations in order to make audible sound.
Although CRT usage has faded, speakers designed for
computers are shielded to avoid magnetic interference with
the CRT's magnetic coil
.


Circuit diagram

interference


interference

is the addition of two or more
waves that results in a new wave pattern.



Interference usually refers to the interaction
of waves that are correlated or coherent with
each other, either because they come from
the same source or because they have the
same or nearly the same frequency.


Interference picture

Transmitter & receiver

Modulation


modulation

is the process of varying one or more
properties of a high
-
frequency periodic waveform
called the
carrier signal
, with respect to a
modulating
signal

(which typically contains information to be
transmitted).


In telecommunicationsmodulation is the process of
conveying a message signal, for example a digital bit
stream or an analog audio signal, inside another
signal that can be physically transmitted.

Demodulation


Demodulation

is the act of extracting the
original information
-
bearing signal from a
modulated carrier wave.



A
demodulator

is an electronic circuit(or
computer program

in a
software defined
radio
) that is used to recover the information
content from the modulated carrier wave.

Conclusion


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