19-11-2012, 06:03 PM
WIRELESS CONTROL VIA MOBILE COMMUNICATION
![Adobe Acrobat PDF .pdf](https://seminarproject.net/images/attachtypes/pdf.gif)
This tutorial just provides the basic knowledge for the beginner to get started with the wireless communication via mobile phone without going into deeper details.
The possibilities are seamless and can be extended easily to IVRS system as well. You do your bit to develop…
WHAT IS DTMF SIGNAL?
The 12 keys on a cellphone( 0,1,…,8,9,*,#) has unique signal associated with itself. This is DTMF signal.
When the call is on, the pressing of any numerical key leads to generation of DTMF signal which is audible on the other side.
HOW ARE DTMF TONE GENERATED?
The extra keys A,B,C and D are not present on cell phone. They are actually specially used for special purposes. For example, publicpayphones that accept credit cards use these additional codes to send the information from themagnetic strip.
TAKING INPUT AND OUTPUT FROM MOBILE
Output can be taken from speaker ( that is near to your ear while calling) and using microphone to convert sound waves to electrical signals …… tedious work.
The other way is through earphone jack.