Gps 32316c

MINOR PROJECT GLOBAL Click to edit POSITIONING Master subtitleSYSTEM style [GPS] Simulation of a GPS Handheld Receiver

Under the noble guidance of Mr. ChanderPal Sharma

Submitted Click to edit By: Master subtitle style Ishika Goel[1671482808] Sushant Sethi[1791482808]

OBJECTIVE OF THE PROJECT A Project in which we build a simulation that gives the location, in 3D, ‘the latitude, longitude and altitude’, of handheld GPS receivers, based on the inputs received by the same from the satellites. ‘The Adaptive Missile Guidance using GPS’ is cited as an example and its function is framed.

INTRODUCTION TO GPS Ø

The Global Positioning System (GPS) is a space based radio positioning/navigation system that will provide three-dimensional position, velocity and time information to suitably equipped s anywhere on or near the surface of the earth.

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The Global Positioning System (GPS) is a system of 31 satellites which circle the earth twice a day in a very precise orbit and transmit information to earth. The GPS navigator we used during our project, must continuously see at least four of these satellites to calculate our position.

How GPS Works Ø

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Satellites send radio signals to the receivers which are on earth surface. Using these signals receiver calculates its location on earth. Using the concept of Spherical Intersections between the outputs of the satellites and the Earth’s surface, a region of probable location of the receiver is calculated.

Three Segments of the GPS Space Segment

Segment Control Segment Ground Antennas Master Station

Monitor Stations

Four Basic Functions of GPS Ø

Position and coordinates.

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The distance and direction between any two waypoints, or a position and a waypoint.

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Travel progress reports.

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Accurate time measurement.

Our Goal Ø

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We will build a MATLAB code, which would take in the position of the satellites as inputs from the . There are a few assumptions made. Using a mathematical computation, we would try to calculate the position of the GPS receiver.

Definition of the Problem d

s2

P s3 s1

All the points with di distances from each satellite i, defines a sphere in the space. We also assume that earth is spherical. The intersection of these two spheres (the earth and sphere defined by all the points with di distances from each satellite i) is a circle on earth surface. For each satellite i, it is the same situation. If we can take the exact distances, these circles - formed with a satellite and earth- intersect exactly at one point and it is our point P.

Formation of a common region

Ambiguity lies in this region

Position Fix Ø Ø Ø Ø

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A position is based on real-time satellite tracking. It’s defined by a set of coordinates. It has no name. A position represents only an approximation of the receiver’s true location. A position is not static. It changes constantly as the GPS receiver moves (or wanders due to random errors). A receiver must be in 2D or 3D mode (at least 3 or 4 satellites acquired) in order to provide a position fix. 3D mode dramatically improves position accuracy.

Waypoint Ø

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A waypoint is based on coordinates entered into a GPS receiver’s memory. It can be either a saved position fix, or entered coordinates. It can be created for any remote point on earth. It must have a receiver designated code or number, or a supplied name. Once entered and saved, a waypoint remains unchanged in the receiver’s memory until edited or deleted.

Three Satellites (2D Positioning)

Three Dimensional (3D) Positioning

Mathematical Computation Ø

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Using the inputs given, we would formulate the equation of a sphere defined by those coordinates, this would be done for each of the satellites. The intersection of these spheres would give rise to a common region. Once the common region is calculated, we would implement a probability distribution in that region to compute the location of the receiver.

GPS Satellite Geometry Ø

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Satellite geometry can affect the quality of GPS signals and accuracy of receiver trilateration. Dilution of Precision (DOP) reflects each satellite’s position relative to the other satellites being accessed by a receiver. It’s usually up to the GPS receiver to pick satellites which provide the best position triangulation. Some GPS receivers allow DOP to be manipulated by the .

Good Satellite Geometry N

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Good Satellite Geometry

Poor Satellite Geometry N

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Poor Satellite Geometry

Practical Errors Earth’s Atmosphere

Solid Structures

Metal

Electro-magnetic Fields

THANK YOU Click to edit Master subtitle style