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Controlling Home Appliances Using Cell Phone
| Content Provider | Semantic Scholar |
|---|---|
| Author | Richards, Johny Rao, Manoj Ramesh |
| Copyright Year | 2013 |
| Abstract | This project deals with the application of the Dual tone multi-frequency(DTMF) technology used in telephones and mobile communication, in real time for controlling electrical appliances in our daily use. It uses a DTMF decoder along with a microcontroller (adruino) to control appliance from a remote location. ———————————————————— INTRODUCTION This experiment brings out the use of home appliances with the help of a remote. The remote can emit only ir radiations and this radiation is alone involved in the process of communication between the appliance and the handicapped person. This idea can be brought out practically which could help out the disabled. Dual-tone multi-frequency signaling (DTMF) is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. Multi-frequency signaling is a group of signaling methods that use a mixture of two pure tone sounds. Various MF signaling protocols were devised by the Bell System and CCITT. The earliest of these were for inband signaling between switching centers, where longdistance telephone operators used a 16-digit keypadto input the next portion of the destination telephone number in order to contact the next downstream long-distance telephone operator. This semi-automated signaling and switching proved successful in both speed and cost effectiveness. Based on this prior success with using MF by specialists to establish long-distance telephone calls, Dualtone multi-frequency (DTMF) signaling was developed for the consumer to signal their own telephone-call's destination telephone number instead of talking to a telephone operator. I. KEYPAD The DTMF keypad is laid out in a 4×4 matrix, with each row representing a low frequency, and each column representing a highfrequency. Pressing a single key (such as '1' ) will send a sinusoidal tone for each of the two frequencies (697 and 1209 hertz (Hz)). The original keypads had levers inside, so each button activated two contacts. The multiple tones are the reason for calling the system multifrequency. These tones are then decoded by the switching center to determine which key was pressed. 1209Hz 1336Hz 1477Hz 1633Hz 697Hz 1 2 3 A 770Hz 4 5 6 B 852Hz 7 8 9 C 941Hz * D II. DTMF DECODER The purpose of DTMF decoding is to detect sinusoidal signals in the presence of noise. There are plethora of cost effective integrated circuits on the market that do this quite well. In many (most ?) cases, the DTMF decoder IC interfaces with a microcontroller. In these instances, why not use the microcontroller to decode the sinusoids? Well the answer is because the typical microcontroller based decoder requires an A/D converter. Furthermore, the signal processing associated with the decoding is usually beyond the scope of the microcontroller's capabilities. So the designer is forced to use the dedicated IC or upgrade the microcontroller to perhaps a more costly digital signal processor. Above is the picture of a 4 bit DTMF decoder |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.ijstr.org/final-print/mar2013/Controlling-Home-Appliances-Using-Cell-Phone.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
