FINAL PRESENTATION ON GPS DATA INTERFACIGN WITH GOOGLE

MAP THROUGH WIRELESS COMMUNICATION

Guided by Mr. Ganesh Roy

Assistant ProfessorDept. of IE, CIT Kokrajhar

Prepared by

Bijit Kumar Bhuyan(Gau-c-11/L-210)

Wasim Akram(Gau-c-11/62)

Contents

• Introduction• Working• Mathematics behind GPS• NMEA Format• Various components used in the project• Block Diagram• Circuit Diagram• Circuit description• Results and discussions• Reason for error• Conclusion and future scope• Utilities• Reference

Introduction

Global Positioning System shortly known as GPS is one

of the advanced addition in the field of modern

inventions. It has a wide application in navigation

systems, construction sites, military equipments and

so on. With the new efforts GPS systems are being more

accurate and precise day by day. The forming of GPS system was started in 1973and it became fully operational in 1995.

The Global Positioning System (GPS) network we all use is called Navstar. It is paid for and operated by the US Department of Defense (DoD). This Global Navigation Satellite System (GNSS) is currently the only fully operational system. Other countries like Russia has GLONASS, China has COMPASS and the EU has GALILEO each at varying stages of development or testing. India is working on IRNSS(Indian Regional Navigation Satellite System).

Working

A GPS receiver knows the location of the satellites

because that information is included in the

transmitted data. By estimating how far away a

satellite is, the receiver also knows it is located

somewhere on the surface of an imaginary sphere

centered at the satellite. It then determines the

sizes of several spheres, one for each satellite

and therefore knows the receiver is located where

these spheres intersect.

There are 24 satellites divided in 6 orbital. Each orbital is separated by 60 and has 4 satellites equally spaced. The satellites revolve at an altitude of 20,000 kms above the earth surface with a speed of 14,000km/hr.

Working continued…

The timing and position are two main factors for working of GPS systems. For accurate time GPS satellites are equipped with the most possible precise timing device atomic clock. While positions are monitored by a ground based control unit.

The GPS satellites also suffer the relativity effect. There are two kinds relativity-

Special relativity

General Relativity.

Special Relativity deals with space, time and motion while the General Relativity with gravity and time. As mentioned above GPS satellites move with a speed of 14,000 km/hr so they delay a time duration of 7usec/day. The GPS satellites also revolves at an altitude of 20,000 km where the gravity is weaker than on the earth surface. So they advances a time duration of 45usec/day.

Working continued…

So combining the both effects we can see that a GPS satellite advances a time period of 38usec/day. This may not seem much but it can lead up to an error of 11km/day. So the GPS satellites’ time is reduced by 38usec/day to overcome this problem.

MATHEMATICS BEHIND GPS

As we can see in the first figure for specifying a point on a straight line two fixed points are required and for 2 dimension three points are required. Similarly in case of three dimension fours points will be required.

FIGURE One-dimensional user position

FIGURE Two-dimensional user position

As we can see in the above image three known points(GPS satellites) and an unknown point(user) are there. Now the distance from the three different satellites to the user are as follows

Figure: Use three known positions to find one unknown position.

Equation for user position

The above equation can be written as

Measurement of pseudorange

Now we can see that the above equations are second order equations. So these are difficult to solve using normal calculations. So we liniarise these equations for simplicity.

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The equations after linearization

Equations in matrix form

The solutions of the above equations

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Relation between Cartesian coordinates and longitude latitude

Latitude,

Longitude,

Altitude,

The above relations shows the relation between Cartesian solutions and latitude and longitude value. We can calculate that for kokrajhar with a location ofLatitude=26.4NLongitude=90.27EX=26.89 kmY=5706.51 kmZ=2832.77 km

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NMEA FORMAT

The message from the GPS receiver is obtained in NMEA( National Marine Electronics Association). It is transmitted in a string fashion which contains typically 17 different units within it. Each unit specifies different parameter.

Message Structure:

$GPGGA,hhmmss.ss,Latitude,N,Longitude,E,FS,NoSV,HDOP,msl,m,Altref,m,DiffAge,DiffStation*cs<CR><LF> 

Example:

$GPGGA,092725.00,4717.11399,N,00833.91590,E,1,8,1.01,499.6,M,48.0,M,,0*5B

FieldNo.

Example Format Name Unit Description

0 $GPGGA String $GPGGA - Message ID, GGA protocol header

1 092725.00 hhmmss.sss hhmmss.ss

- UTC Time, Current time

2 4717.11399 ddmm.mmmm

Latitude - Latitude

3 N Character N - N/S

4 00833.91590 dddmm.mmmm

Longitude - Longitude,

5 E character E - E/W

6 1 Digit FS Position Fix Status Indicator

7 8 Numeric NoSV - Satellites Used, Range 0 to 12

Field No. Example Format Name Unit Description

8 1.01 Numeric HDOP - HDOP

9 499.6 Numeric Msl M MSl altitude

10 M Character uMSL - Units, Meters

11 48.0 Numeric Altref M Geoid Separation

12 M Character uSep - Units, Meters

13 - Numeric DiffAge S Age of Differential Corrections, Blank (Null) fieldswhen DGPS is not used

14 0 Numeric DiffStation - Diff. Reference Station ID

Table of Fix Status

Filed No. Example Format Name Unit Description

15 *5B hexadecimal cs - Checksum

16 - Character <CR><LF> - Carriage

Fix Status Description

0 No Fix / Invalid

1 Standard GPS(2D/3D)

2 Differential GPS

6 Estimated (DR) Fix

Various components used in the project

The various components used in the project are mentioned below

• U-Blox NEO-6M GPS Module• RF Trans-receiver• ILX232N IC• RS232 Connector• PC• U-Center v8.10

U-Blox NEO-6M GPS Module

The GPS module receives signal from the GPS satellites and provides data in NMEA format. The baud rate of the GPS module is normally 9600.

RF Trans-receiver

This module is basically used for wireless communication purpose. It works on frequency of 433MHz. It uses ASK and FSK for modulation purpose. The module has two sections receiver and transmitter. The transmitter transmits the data in form signal while the receives the transmitted data.

ILX232N IC

The ILX232N IC used for the shifting of voltage level from 0-3V to 0-5V voltage level. It is necessary for interfacing the data with computer.

RS232 Connector

The RS232 is a 9 pin communication port. In our project we have connected

this connector for sending data from the receiver section to the PC for further

data processing. Here only three pins are used those are Rx, Tx and GND pin.

The other pins are left free as those are not required.

PC

The PC stands here for Personal Computer or simply computer. The PC is an essential part in our project. The received from the GPS module is finally interfaced with Google Map in PC itself. Apart from this the GPS module can be configured for various functions using the u-center software in PC. The computer we are using for our project does not have a 9 pin RS232 COM PORT. So one USB to RS232 9 pin converter cable is also used in the connection.

U-Center Software

• Export data files to Google Earth and Google Maps. • Supports (Multiple GNSS) AssistNow Online and AssistNow Offline. • Data recording and playback function. • Structural and graphical data visualization in real-time. • Export functionality to standard PC applications. • Docking views (real-time cockpit instruments): Satellite constellation,

compass, clock, altimeter, speedometer, GNSS and satellite information views.

• Download firmware updates to GNSS positioning modules.

Block diagram

The block diagram of the project is shown blow. It shows a simplified representation of the project work. In the project the GPS data is transmitted and received through the RF trans-receiver for wireless communication. The data is then fetched in the computer through the interfacing with ILX232N IC. For interfacing RS232 protocol is also used. Finally in the PC u-center software is used for interfacing with Google Map.

Circuit Diagram

Circuit Description

The GPS receiver is basically a three terminal module. The two terminals are for power supply with 3V and ground connection. The other terminal is for data transmission purpose. In the module used in the project a receiver terminal is also there. This plays a role when the configuration of the GPS module is required. By default the module transmits data with 9600 baud rate in NMEA format. Now from the power supply it is obvious that the voltage level of the transmitted data is in between 0V to 3V. Now this data is transmitted through the RF transmitter. The RF transmitter we are using here is R433A module.

In the receiver section the data transmitted by the transmitter is received. Since the voltage level is in the 0-3V range we use another IC ILX232N. The connections are made as per the circuit diagram and thus we receive a compatible voltage level to connect with the computer. Finally in the computer u-center software is used for evaluation and various processing. The data is interfaced with Google Map to show the GPS receiver location.

Results and Discussions

The following diagram shows the signal received from GPS receiver. The signal that is generated by the GPS receiver is monitored by the Oscilloscope and its frequency is found to be around 5 KHz. The mean voltage is 1.64V with a peak to peak voltage of 4.44V.

Signal from RF receiver

The transmitted signal is effectively received by the RF receiver. The received signal has a frequency of around 3 KHz with a mean voltage of 3.36V. The peak to peak voltage is 5.20V.The following is the output of the test signal that is transmitted from RF Tx.

Signal from the IC

The signal received in the receiver section is fed to the ILX232N IC. The IC changes the voltage level of the signal to make it suitable for interfacing with PC. The signal has frequency of around 3KHz with mean voltage 0. The peak to peak voltage is 14.88V.

Final output from the PC

Finally the data is received in the computer. Here the GPS data is interfaced with Google Map using the u-center software. The following image shows the result

Another work is done in the interfacing aspect. A local map image is taken and it is calibrated using the software according to the specific longitude and latitude value and the result is obtained as follows.

Reasons for error

• Ionosphere and troposphere delays • Signal multi path• Receiver clock errors• Orbital errors• Number of satellites visible• Intentional degradation of the satellite

Conclusion and Future Scope

Conclusion

In this project we have firstly tested the GPS module by monitoring the data in oscilloscope. Then we have connected the GPS module with the PC through a USB to TTL converter module. The data is seen on the u-center software in message view and other view. The data is in the NMEA format. Then we have successfully used the RF trans-receiver for wireless communication. This is a 433MHz RF module. The module uses ASK for data transmission. Then we have implemented ILX232N IC for voltage level shifting to make it compatible for interfacing with PC. For connecting with PC RS232 communication port is used. Finally in the PC we have successfully made the interfacing with the Google Map through u-center software. A local map is also calibrated for showing the location.

 

5.2 Future Scope

In our project we have used RF trans-receiver for the wireless communication purpose. It restricts the range of the system within 50- 100 m range. This can be improvised by using a GSM module to increase the range of the system. The current system can be cascaded with other system for automatic motion control in sophisticated areas.

Utilities

The current system can be independently used for location tracing in a small area under observation. This can be beneficiary in sophisticated areas like various industries and high security places. The system can also be cascaded with any moving vehicle for automatic movement in a small region of interest. This can be helpful in various industries for automatic vehicle movement purpose.

REFERENCEReferences

Books:

[1] James Bao Yen Tsui, “Fundamentals of Global Positioning System Receivers: A Software Approach”, a wiley interscience publication john wiley & sons, inc. 2000.

 

Journals:

[1] Hayward R, Marchick A, Powell J.D., “Single baseline GPS based attitude heading reference system (AHRS) for aircraft applications”, American Control Conference, volume 5, IEEE, 1999

[2] Pochmara J, Palasiewicz J, Szablata P, “Expandable GSM and GPS systems simulator”, Mixed Design of Integrated Circuits and Systems (MIXDES), IEEE, 2010

[3] Tae Hee Kim, Cehon Sig Sin, Sanguk Lee, Jae Hoon Kim, “Analysis of performance of GPS L1 signal generator in GPS L1 signal”, IEEE, 2014

 

Websites:

[1] http://www.bms.by/eng/spec/PDF/ILX232_e.pdf

[2]http://www.u-blox.com/en/evaluation-tools-a-software/u-center/u-center.html

Thank you