Gps

UST Biological Sciences BIO 203L

Global Positioning System .

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GA. Ferrer M. Guillermo CM. Marasigan K. Medina

Submitted: 19 December 2013

ABSTRACT Each group was given coordinates to follow through a global positioning system or GPS. These coordinates led the groups to specific objects or landmarks inside the vicinity of the school. Group 4 from Team A was given the coordinates N 14o36.633’ E 120o59.404’ which led them in front of the University of Santo Tomas Hospital (USTH letters). The group properly used the global positioning system and was able to correctly identify the object being searched for. Keywords ·Global ·Coordinates

Positioning

System

Introduction The Global Positioning System (GPS) is a satellite-based navigation system that was developed in 1970 by the U.S. Department of Defense for military needs of the U.S. soldiers. At present, this devise does not only serve military purposes but it is now a dual-use system that can be accessed by both military and civilian users (El-Rabbany, 2002). Since GPS provides continuous positioning and timing

information, it has become important in many fields of science such as ecology, forestry, geography, geology, surveying, limnology and oceanography. GPS can be used to obtain accurate location of a certain object within the planet or it provides the operator accurate information regarding his or her precise location in respect to the network of satellites orbiting the earth and his or her position within the planet. The usage of this equipment provides ecologists a convenient way in locating individual organism or groups of organism they are studying, recording the location of their samples, and etc. Because of high accuracy of GPS in measuring the location of a certain area, it is useful in many ecological observations such as the monitoring of spatial distribution of a certain organism, population or community in a given location, preparation for future study, sampling, mapping or protection, and providing information regarding a definite sensitive location such as that of the wetlands. The GPS works accurately through its three essential segments: the space

UST Biological Sciences BIO 203L

segment, the control segment and the user segment. The control segment traces each satellite and time to time uploads to the satellite its prediction of the future satellite positions and satellite clock time corrections. These predictions sent by the satellite are constantly transmitted to the user as part of the navigation message. The space segment which consists of 24 satellites transmits ranging signal to the user receiver stating current position and time correction. The user receiver is the one that collects ranging signals from a particular satellite and calculates the three-dimensional position and local time (Parkinson & Spiker , 1996).

were tasked to take a picture of all the sides of the object and write what that landmark is behind the piece of paper where their coordinates were written. The first group from both teams started the race and once they got back the second group went out. The second group then passed the GPS to the next group until the last group from the team found their specific landmark. Group 4 from Team A was given the coordinates N 14o36.633’ E 120o59.404’. Results

In this experiment the objectives were as follows: 1. To be able to determine the use of handheld GPS receivers to establish sampling stations, revisit those situations 2. To be able to delimit a simulated ecological sensitive area, and navigate t a location known only by its coordinates using GPS.

Methodology The class was divided into two teams with five groups each. Each group was given coordinates, written in a piece of paper, to be able to find a specific object or landmark inside the vicinity of the campus. A global positioning system or GPS was provided to make this possible. Once the group is able to find the right position, they

Figure 1 USTH (object/landmark tasked to locate)

The coordinates led group 4 in front of the University of Santo Tomas Hospital where there are four letters, USTH, which comprise the acronym of the hospital. All the groups were tasked to capture an image from the point of the object or landmark found and in this case, the group took a picture five meters from the letters in front of the hospital which are USTH. The succeeding images are pictures showing the areas five meters away from the object or landmark in different directions.

UST Biological Sciences BIO 203L

Figure 2 Image taken to view area five meters from the left of the letters

Figure 5 Image of GPS

The picture above was taken to show the coordinates given by the GPS when the group stood by the letters.

Discussion

Figure 3 Image taken to view area five meters from the right of the letters

Figure 4 Image taken to view area five meters in front of the letters

Positioning and navigating are the most important applications of the GPS. The GPS measures the distance between the receiver and the satellites from which the GPS acquires its signal. This in turn, determines the position of the receiver. The reference points of the location must come from at least three satellites (Xu, 2007). Each of the satellites has a certain area that they could reach and at some point these areas intersect. So as the group moved towards the correct coordinates, the members moved in a zone accessible by certain satellites. Time can also be a cause of inaccuracy because of the delay due to the mobility of the receiver. This affects the signal transmission for it increases the gap

UST Biological Sciences BIO 203L

between the receiver and the satellites therefore affecting the determination of the position. The signal might be blocked by some infrastructures and the like but when you stop in an open area, the signal transmission will be cleared. So when the group reached the area where the object or landmark is located, they stopped to get a right reading of the GPS. The group were able to determine the object or landmark being asked to find due to the instructor's directions. Basically, the GPS points to an area where an exact object might be placed. Coordinates changes due to time because there is continuous motion both from the satellites and the Earth. Conclusion GPS device is a very useful tool in research. In the experiment, the group was able to determine the location being specified by the given coordinated with the help of the GPS device. Although using very far antennas, the GPS device pointed out specific place that helped the group to determine the place. By matching the performance of the GPS device to the different groups, the GPS device was determined to be accurate by approximately within 5 meter radius or within the line of sight of the location. Errors occur but the error was very close enough to the correct position being targeted.

References El-Rabbany, A. (2002). Introduction to GPS: The Global Position System. USA: Artech House, Inc.

Parkinson, B. W., & Spiker , J. J. (1996). Global Positioning Sysytem: Theory and Application. USA: American Institure of Aeronautics and Astronautics. Xu, G. (2007). GPS Theory, Algorithms and Applications 2nd Edition. Potsdam, Germany: Springer.