Survey using GPS(Global Positioning System)

Hi everyone,
                    This is my second assignment about the first survey which we done in our campus to calculate the distance between different points using Global Positioning System(GPS).The GPS which we used was a simple handling device.Here we calculate the distance between  any two points by noting down the latitude and longitude of the points and mathematically we can calculate the distance in kilometres/metres (in which ever unit we want).In our survey we have have taken the latitude and longitude of three points using GPS.So we can calculate the distance between any two points mathematically.The three points which we noted are:

Point 1 :  8° 37′ 29.7′′ N, 77° 01′ 56.4′′ E
Point 2 :  8° 37′ 35.1′′ N, 77° 01′ 55.35′′ E
Point 3  : 8° 37′ 37.633′′ N, 77° 02′ 00.05′′ E

point 1 was our physical science block,point 2 was a pole in construction site and point 3 was SAC(student activities centre).

1 degree of latitude corresponds to a distance of 111 km on the ground.
1 degree of longitude corresponds to a distance of 111*cos(latitude) on the ground.

Now from these three points we can calculate the distance between any two points.

Distance between point1 and point2:
Point 2 - Point 1: [ 8° 37′ 35.1′′ N, 77° 01′ 55.35′′ E] - [ 8° 37′ 29.7′′ N, 77° 01′ 56.4′′] = [5.4′′ N, -1.05′′ E]
Therefore distance between point1 and point2(in km/m) is:
N = 5.4*111/3600 ≈ 0.1665km ≈ 166.5m
E = -1.05*111/3600  ≈ -0.032375km ≈ -32.375m
Here the negative sign just indicates the direction.

Distance between point2 and point3:
Point 3 - point 2: [ 8° 37′ 37.633′′ N, 77° 02′ 00.05′′ E ] - [ 8° 37′ 35.1′′ N, 77° 01′ 55.35′′ E ] = [2.533′′ N, 4.7′′ E]
Therefore distance between point2 and point3(in km/m) is:
N = 2.533*111/3600  ≈ 0.0781km ≈ 78.1m
E = 4.7*111/3600  ≈ 0.1449166km ≈ 144.9166m

Therefore,
The total distance travelled North ≈ [ 166.5+78.1 ]≈ 244.6mN
And total distance travelled East  ≈ [ 144.9166-32.375 ]  ≈ 112.5416mE

Note:
The values so obtained above are all approximate.

ABOUT GPS:

• The Global Positioning System (GPS) also called as NAVSTAR(Navigation Satellite System Using Timing and Ranging ) is a space-based global navigation satellite system (GNSS) that provides reliable location and time information in all weather and at all times and anywhere on or near the Earth when and where there is an unobstructed line of sight to four or more GPS satellites. It is maintained by the United States government and is freely accessible by anyone with a GPS receiver.

GPS was established in 1973 mainly for military purposes.But after the korean incident it was given even for civilian purposes.At first it was run with 24 satellites.But now it is running with more than 30 satellites.
Each satellite is built to last about 10 years.and replacements are constantly being built and launched into orbit.
In 1978, the first experimental Block-I GPS satellite was launched.

• GPS satellites circle the earth twice a day in orbit and transmit signal information to earth. GPS receivers take this information and use triangulation technique to calculate the  location.Atleast three satellites are required for the receiver to determine a 2D position (latitude and longitude) and track the movement. With four or more satellites, the receiver can determine the user's 3D position (latitude, longitude and altitude). The GPS unit can calculate other information such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time and etc.
• The satellites that make up the GPS space segment are orbiting  the earth about 12,000 miles above us. They are constantly moving, making two complete orbits in less than 24 hours. These satellites are travelling at speeds of roughly 7,000 miles an hour.The GPS appears as below:

Links:http://en.wikipedia.org/wiki/Global_Positioning_System

some of the photos which we took during our survey: