SUBMITTED BY ARJUN S KUMAR

ARUN JOE JOSEPH

DEEPA RAMACHANDRAN

DON PAUL P

ROSHNI S A

INTRODUCTION

Call costs that are generated for voice

calls within an institution could turn out

to be a handful if not managed properly.

This project aims to develop a system

which can be used for voice

communication over a Wi-Fi network

provided within an institution.

It would help to nullify the costs for voice

communication within an institution

OBJECTIVE To develop an application based on Python to enable

voice communication between devices that are connected to the same Wi-Fi network.

To assemble a mobile terminal with following features:

Full Duplex communication over Wi-Fi.

User interface with an LCD display and Keypad input.

To support future extension of this system to accommodate new devices.

BLOCK DIAGRAM

INTERFACING DIAGRAM

DESCRIPTION

Voice input is given to raspberry pi via

microphone connected to the audio

input of sound card.

Raspberry pi is used to process and

transmit voice signals.

Wi fi dongle provides Wi-fi access to

raspberry pi.

Voice signal is sampled and transmitted

via Wi-fi.

LCD and keypad constitute user interface part.

LCD displays the welcome message and messages indicating call initiation and termination.

In order to connect to a device, its IP address must be entered. This is done using interfaced keypad.

The LCD also displays the IP address and port number of the destination.

RASPBERRY PI

SPECIFICATIONS OF RASPBERRY

PI (MODEL B)

ARM1176JZF-S700 MHz processor

VideoCore IV GPU

RAM-512 MB

No built-in hard disk or solid-state drive

Uses an SD card for booting and long-

term storage.

2 USB ports

10/100 Ethernet controller

Linux kernel - based operating systems

Raspbian is a Debian - based free

operating system optimized for the

Raspberry Pi hardware.

SPECIFICATIONS IN BRIEF

Wi-Fi

Wi-Fi is a popular technology that allows

an electronic device to exchange data or

connect to the internet wirelessly using

radio waves.

Spaces where cables cannot be run,

such as outdoor areas and historical

buildings, can host wireless LANs.

An economical networking option.

LCD

LCDs are economical, easily programmable,

have no limitation and can display special

and even custom characters (unlike seven

segment display).

A 16x2 LCD means it can display 16

characters per line and there are 2 such

lines.

In this LCD each character is displayed in

5x7 pixel matrix.

This LCD has two registers, namely,

Command and Data.

Command-stores instructions.

Data-stores ASCII value of character to

be displayed.

KEYPAD

Basic 16 button keypad.

16 buttons of this keypad are arranged in a 4x4 grid.

The keys are connected into a matrix, so, we only need 8 output pins (4-columns and 4-rows) to scan through the pad.

An 8-pin extra-long header strip is provided so that it can be plugged in to the desired GPIO pins.

SERVER SIDE

SERVER SIDE

CHUNK = 1024

FORMAT = pyaudio.paInt16

CHANNELS = 1

RATE = 44100

RECORD_SECONDS = 10

WIDTH = 2

frames = []

HOST = '' # Symbolic name meaning all available interfaces

PORT = 50010 # Arbitrary non-privileged port

p = pyaudio.PyAudio()

stream =

p.open(format=p.get_format_from_width(WID

TH),

channels=CHANNELS,

rate=RATE,

output=True,

frames_per_buffer=CHUNK)

s = socket.socket(socket.AF_INET,

socket.SOCK_STREAM)

s.bind((HOST, PORT))

s.listen(1)

conn, addr = s.accept()

print 'Connected by', addr

data = conn.recv(1024)

CLIENT SIDE

CLIENT SIDE

import socket

import pyaudio

import wave

import time

#record

CHUNK = 16384

FORMAT = pyaudio.paInt16

CHANNELS = 1

RATE = 22050

RECORD_SECONDS = 60

HOST = raw_input("enter IP") # The remote host

PORT = input("enter port") # The same port as used by the server

num=1

while num==1:

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

s.connect((HOST, PORT))

p = pyaudio.PyAudio()

stream = p.open(format=FORMAT,

channels=CHANNELS,

rate=RATE,

input=True,

frames_per_buffer=CHUNK)

print("*recording")

frames = []

for i in range(0, int(RATE/CHUNK*RECORD_SECONDS)):

data = stream.read(CHUNK)

frames.append(data)

s.sendall(data)

print("*done recording")

stream.stop_stream()

stream.close()

p.terminate()

s.close()

PORT=PORT+2

print("*closed")

num1=raw_input('press 1 to continue')

print('exit')

PROJECT SUMMARY

The objective was to develop

1) full duplex communication system

2) A user interface for interacting

We have successfully implemented both of

our objectives.

Why Python?

Python is easy to write when compared

to JAVA.

It is Dynamically typed language , so

that program length reduces.

It has good compatibility with Raspberry

Pi.

Why Raspberry Pi?

It is the cheapest available hardware

unit that satisfied our requirements.

It has GPIO pins tat enabled to interface

with external hardware.

It has a huge online support.

THE FEATURES OF FINAL END

PRODUCT

The device we developed is of compact

size and works stand alone.

It has at present a range of about 10m

circular radius from base station.

It offers reconnecting and retry features

It can be configured for any Wi-fi

network.

OTHER APPLICATIONS OF

PROJECT

Can be used at disaster management

locations as the last resort of medium

range communication.

Can be used as a broadcast device for

wireless audio speakers.

FUTURE DEVELOPMENTS

Range can be extended by using a more

powerful router.

When going for mass production the

cost can again be reduced.

Can add texting features as well.