29-08-2011, 02:13 PM
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3.1 INTRODUCTION:
Radio control (often abbreviated to R/C or simply RC) is the use of radio signals to remotely control a device. The term is used frequently to refer to the control of model vehicles from a hand-held radio transmitter. Industrial, military, and scientific research organizations make [traffic] use of radio-controlled vehicles as well.
A remote control vehicle is defined as any mobile device that is controlled by a means that does not restrict its motion with an origin external to the device. This is often a radio control device, cable between control and vehicle. A remote control vehicle (Also called as RCV) differs from a robot in that the RCV is always controlled by a human and takes no positive action autonomously.
One of the key technologies which underpin this field is that of remote vehicle control. It is vital that a vehicle should be capable of proceeding accurately to a target area; maneuvering within that area to fulfill its mission and returning equally accurately and safely to base.
Recently, Sony Ericsson released a remote control car that could be controlled by any Bluetooth cell phone. Radio is the most popular because it does not require the vehicle to be limited by the length of the cable or in a direct line of sight with the controller (as with the infrared set-up). Bluetooth is still too expensive and short range to be commercially viable.
3.2 BLOCK DIAGRAM:
DESCRIPTION:
As shown in the above block diagram, first block is the cell phone. So, it acts as a DTMF generator with tone depending upon key pressed. DTMF Decoder, i.e., IC HT9170 decodes the received tone and gives binary equivalent of it to motor driver IC L298 which will drive the two DC motors connected to it. The concept used for driving is ‘Differential Drive’. So ultimately two motors rotate according to the key pressed on the keypad of the cell phone.
3.3 TECHNOLOGY USED:
3.3.1 Dual-Tone Multi-Frequency (DTMF):
Dual-tone multi-frequency (DTMF) signaling 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. The version of DTMF used for telephone tone dialing is known by the trademarked term Touch-Tone (canceled March 13, 1984), and is standardized by ITU-T Recommendation Q.23. It is also known in the UK as MF4. Other multi-frequency systems are used for signaling internal to the telephone network. As a method of in-band signaling, DTMF tones were also used by cable television broadcasters to indicate the start and stop times of local commercial insertion points during station breaks for the benefit of cable companies. Until better out-of-band signaling equipment was developed in the 1990s, fast, unacknowledged, and loud DTMF tone sequences could be heard during the commercial breaks of cable channels in the United States and elsewhere.