With today's global position system (GPS) receivers, we are able to pinpoint our own position, but what's more useful about GPS receivers is that they can transmit our position information to other receivers. We decided to use both of these features to create a wireless vehicle navigation system.
To design the navigation system, we combine the GPS ability to pinpoint location along with the ability of the global system for mobile (GSM) to communicate with a remote system (Mobile Phone) in a wireless fashion. Information from the Satellites is displayed on graphical LCD.
The global positioning system, usually called GPS, is the only fully-functional satellite navigation system. A constellation of more than two dozen GPS satellites broadcasts precise timing signals by radio, allowing any GPS receiver (abbreviated to GPSr) to accurately determine its location (longitude, latitude and altitude)in any weather, day or night, anywhere on earth.
GPS allows receivers to accurately calculate their distance from the GPS satellites. The receivers does this by measuring the time delay between the signal sent by satellite and the local time when the signal is received. This delay, multiplied by the speed of light, gives the distance to that satellite. The receiver also calculates the position of the satellite based on information periodically sent in the same signal. By comparing the two, position and range, the receiver can discover its location.
[...] A receiver is often described by its number of channels: this signifies how many satellites it can monitor simultaneously Many GPS receivers can relay position data to a PC or other device using the NMEA 0183 protocol means by which marine instruments and also most GPS receivers can communicate with each other. NMEA 2000 is a newer and less widely adopted protocol. Both are proprietary and controlled by the US- based National Marine Electronics Association. (NMEA) GPS satellites broadcast three different types of data in the primary navigation signal. [...]
[...] The clock driving the timers is called TCLK and is determined by the setting of two bits (PT1, PT0) in the System Configuration Register (SCR). The frequency of TCLK may be selected to be the oscillator input divided by 4 the oscillator input divided by 16 (Osc/16), or the oscillator input divided by 64 (Osc/64). This gives a range of possibilities for the XA timer functions, including baud rate generation, Timer 2 capture. Note that this single rate setting applies to all of the timers. [...]
[...] void lcdline1(void) { lcdcmd(0x80); } void lcdline2(void) { lcdcmd(0xc0); } void lcdline3(void) { lcdcmd(0x94); } void lcdline4(void) { lcdcmd(0xd4); } void clearscreen(void) { lcdcmd(0x01); } void delay(unsigned char del) { int for _delay_ms(100); } gsm data receive void USART_Init(void) { USART0 Receiver: On,USART0 Transmitter: On,USART0 Mode: Asynchronous USART0 Baud rate: 11520 UCSR0A=0x00; UCSR0B=0x98; UCSR0C=0x06; UBRR0H=0x00; UBRR0L=0x67; Enable the Global Interrupt Enable flag so that interrupts can be processed } ISR(USART0_RX_vect) { ReceivedByte = UDR0; Fetch the recieved byte value into the variable "ByteReceived" b[i]=ReceivedByte; } void USART_Transmit( unsigned char data ) { while ( UCSR0A & (1 [...]
[...] It becomes a universal measurement system capable of positioning things on a very precise scale. Differential GPS involves the cooperation of two receivers, one that's stationary and another that's roving around making position measurements. The stationary receiver is the key. It ties all the satellite measurements into a solid local reference. So if two receivers are fairly close to each other, say within a few hundred kilometers, the signals that reach both of them will have traveled through virtually the same slice of atmosphere, and so will have virtually the same errors. [...]
[...] The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. GPS uses these "man-made stars" as reference points to calculate positions accurate to a matter of meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter! In a sense it's like giving every square meter on the planet a unique address. GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very economical. [...]
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