Design And Construction Of A Dual Tone Multi Frequency Based Load Sharing /Switching System Using Gsm

ABSTRACT

The project aims at controlling various loads spread over a large area remotely by using DTMF concept. The DTMF command tone thus received from the phone causes electrical load switching. The project is useful for managing industrial, domestic or agricultural loads that extend over a large area.
The project requires a DTMF decoder interfaced to audio output socket of the cell phone. Whenever a button on the keypad is pressed the frequency thus generated from it is received by the decoder and it converts the frequency into its equivalent digital code. A microcontroller of 8051 family is used which is interfaced to relays through relay driver IC. The digital code is then provided to microcontroller that identifies the phone commands and initiates the relays to actuate the respective loads by turning them on and off.

CHAPTER ONE

1.1                                                        INTRODUCTION

Generally, several home equipment can be controlled by switches. But these days we can observe the home automation to control the appliances using various technologies. This article presents the DTMF based load control system. The term DTMF stands for Dual Tone Multi Frequency is a signalling system for recognizing the DTMF keys on a keypad. The applications of DTMF include telecommunication signalling over analogue telephone lines in the voice frequency band among telephone handsets and communication devices. So, when you make a call for customer care they will request you to push any number. When you push any number on your mobile keypad, one specific action will occur because of DTMF. When a keypad button is pressed in a mobile keypad, instantly it will produce a tone of two frequencies called column and row frequencies.

DTMF based Load Control System using 8051 Microcontroller was built in this work, which is a simple project that helps is controlling different loads (electrical appliances) with the help of DTMF Technology. DTMF or Dual Tone Multi Frequency is a signaling technique that is often used in the field of telecommunication (telephones to be specific).

In the DTMF based Load Control System using 8051 project, we are using different communication technologies like DTMF and GSM for controlling our home appliances using a cell phone (mobile phone).

1.2                                                   AIM OF THE PROJECT

The main aim of the project is to control a device that will control the functioning of the industrial/ agricultural load using wireless technology.

1.3                                             OBJECTIVE OF THE PROJECT

At the end of this work, student involved will be able to build a device that:

• The control the functioning of the industrial/ agricultural load using wireless technology.
• The mobile is connected to the DTMF decoder IC and a call is made to data mobile from another mobile.
• When the network path is formed, any mobile key is pressed.
• If 1 is pressed then this tone is decoded to 4 digit data and given to MC by inverting the data.
• MC compares this data and an output port which is connected to ULN gets logic high and the output of ULN is low which makes the relay ON. Hence, load 1 will be ON.

1.4                                                 SCOPE OF THE PROJECT

One cell phone will send digitized commands to another cell phone which is in auto answering mode at the receiving end.  The receiving cell phone codes are fed to the microcontroller which is programmed to recognize those codes for operating any kind of load duly interfaced through relays and relay drivers as per the sent commands from the senders mobile

1.5                                         APPLICATIONS OF THE PROJECT

• Using this technology, the loads can be activated from anyplace
• The applications of DTMF (dual tone multi frequency) mainly include home, industries, agriculture, etc.
• These tones are used at the telephone switch centres for discovery of calls or dialled number and also used by a particular cable network
• This n/w’s uses DTMF tones to specify a local cable operator when a local add is to be put in. In allocation, this is identified as local placing. These tones were also used by global stations for switching ON & OFF remote transmitters

From the above information, finally, we can conclude that by using Dual Tone Multi Frequency technology and microcontroller, the loads can be operated from any place.

1.6                                          ADVANTAGES OF THE PROJECT

• You can use the DTMF based Load Control System using 8051 Micro controller to remotely control any loads using GSM and DTMF technologies.
• We can turn ON or OFF the appliances from anywhere and at any time.
• We need not worry if forgot to switch OFF any appliance while we are going out as we can turn them OFF at our convenience.

1.7                                          LIMITATIONS OF THE PROJECT

• Anyone with the mobile number of the phone at the circuit can control the loads.
• You can control only 16 loads at the maximum.