A study of global position system (GPS) receivers
- Embedded system
- History and advantages
- Hardware description
- Block diagram
- Circuit description
- GPS receiver
- GSM modem
- Microcontroller (PHILIPS XA-G39)
- LCD display
- Serial communication (RS 232)
- Power supply
- Flow chart of GPS/GSM
- Working of GPS
- Software description
- AT commands
- KEIL software and programming
- Program of the project
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. [...]
[...] The SVs then send subsets of the orbital ephemeris data to GPS receivers over radio signals 2.ANA LOGIC'S GSM SMART MODEM Ana logic's GSM Smart Modem is a multi-functional, ready to use, rugged and versatile modem that can be embedded or plugged into any application. The Smart Modem can be customized to various applications by using the standard AT commands. The modem is fully type-approved and can directly be integrated into your projects with any or all the features of Voice, Data, Fax, SMS, and Internet etc. [...]