1. Satellite (GPS) controlled
robot

2. What is GPS?
The Global Positioning System (GPS) is a space-based global
navigation satellite system that provides reliable location and
time information

3. Who maintains it?
It is maintained by the United States government and is freely
accessible by anyone with a GPS receiver.

4. How many GPS satellite are there?
A constellation of 27
Earth-orbiting satellites
(24 in operation and
three extras in case one
fails)

5. How GPS receiver works?
The GPS satellites transmit signals to a GPS receiver. These
receivers passively receive satellite signals in form of NMEA
statements (NMEA Sentence) with useful information like global
position, time etc.. They do not transmit and require an unobstructed
view of the sky, so they can only be used effectively outdoors.

6. Contd…
Each GPS satellite transmits data that indicates its location and the
current time. All GPS satellites synchronize operations so that these
repeating signals are transmitted at the same instant. The signals,
moving at the speed of light, arrive at a GPS receiver at slightly
different times because some satellites are further away than others.
The distance to the GPS satellites can be determined by estimating
the amount of time it takes for their signals to reach the receiver.
When the receiver estimates the distance to at least four GPS
satellites, it can calculate its position in three dimensions.

7. What is NMEA?
The NMEA Mission The National Marine Electronics
Association (NMEA) is the unifying force behind the entire
marine electronics industry, bringing together all aspects of the
industry for the betterment of all in our business.

8. What is NMEA 0183?
NMEA 0183 (or NMEA for short) is a combined electrical and
data specification for communication between marine electronic
devices such as echo sounder, sonar, anemometer (wind
speed and direction), gyrocompass, autopilot, GPS receivers
and many other types of instruments
GPS receiver communication is defined within this specification

9. What is NMEA messages/statements?
The NMEA messages or statements are the set of strings received by the
receiver which contain the set of information e.g. Latitude, Longitude , altitude,
time etc.

10. Example of NMEA statement:
$GPGGA,115220.000,2834.7690,N,07720.5587,E,1,6,1.43,199.1,M,-36.0,M,,*79<CR><LF>
This is the statement received by the GPS module at Robosapiens India’s office
In this statement: 28 degree 34.7690 minutes is the latitude
077 degree 20.5587 minutes is the longitude
(Read PDFs given in your CD for detail description of this statement)

11. How GPS Module look a like?

12. How to use this?
• Give 3.3V VCC and GND supply, your module
will start transmitting NMEA statements from Tx
Pin.
• Connect Tx pin with Rx Pin of MCU and read
all these statements in MCU

13. What GPS Module will transmit?
$GPVTG,163.31,T,,M,1.31,N,2.43,K,A*3D
$GPGGA,115218.000,2834.7698,N,07720.5591,E,1,7,1.04,199.3,M,-36.0,M,,*7D
$GPGSA,A,3,28,08,07,15,11,17,26,,,,,,1.35,1.04,0.85*0E
$GPRMC,115218.000,A,2834.7698,N,07720.5591,E,1.03,174.01,160710,,,A*67
$GPVTG,174.01,T,,M,1.03,N,1.90,K,A*34
$GPGGA,115219.000,2834.7693,N,07720.5588,E,1,6,1.43,199.2,M,-36.0,M,,*7C
$GPGSA,A,3,28,08,15,11,17,26,,,,,,,1.69,1.43,0.90*07
$GPRMC,115219.000,A,2834.7693,N,07720.5588,E,1.00,191.81,160710,,,A*65
$GPVTG,191.81,T,,M,1.00,N,1.85,K,A*30
$GPGGA,115220.000,2834.7690,N,07720.5587,E,1,6,1.43,199.1,M,-36.0,M,,*79
$GPGSA,A,3,28,08,15,11,17,26,,,,,,,1.69,1.43,0.90*07
$GPRMC,115220.000,A,2834.7690,N,07720.5587,E,0.92,181.54,160710,,,A*60
$GPVTG,181.54,T,,M,0.92,N,1.70,K,A*39
$GPGGA,115221.000,2834.7690,N,07720.5582,E,1,6,1.43,198.9,M,-36.0,M,,*74
$GPGSA,A,3,28,08,15,11,17,26,,,,,,,1.69,1.43,0.90*07
$GPGSV,3,1,11,17,71,313,22,08,57,149,26,28,55,036,18,11,28,051,17*76
..........
...........

14. How to filter out Latt. And Long. from
statements?
Receive these statements on Rx pin of the microcontroller
by using UART with 9600 bps baud rate, 8 data bits, no
parity, and 1 stop bit (default settings)
Filter the information with normal string operation and
save it in string/array variables

15. How to use filtered out information?
Use this information to navigate your robot from one
location to another location. Location can be compared by
strcmp function.

16. Thank you…