Subject Paper No and Title Module No and Title Module Tag Geology Remote Sensing and GIS Concepts of Global Navigation Satellite RS & GIS XXXIII Principal Investigator Co-Principal Investigator Co-Principal Investigator Prof. Talat Ahmad Vice-Chancellor Jamia Millia Islamia Delhi Prof. Devesh K Sinha Department of Geology University of Delhi Delhi Paper Coordinator Content Writer Reviewer Prof. P. P. Chakraborty Department of Geology University of Delhi Delhi Dr. Atiqur Rahman Department of Geography, Faculty of Natural Sciences, Jamia Millia Islamia Delhi Dr. Atiqur Rahman Department of Geography, Faculty of Natural Sciences, Jamia Millia Islamia Delhi Prof. Naved Ahsan Department of Civil Engineering Jamia Millia Islamia Delhi
Table of Content 1. Introduction [Global Navigation Satellite ] 1.1 Space Segments 1.2 Control Segments 1.3 User Segments 2. Summary
1. Introduction A satellite navigation system (Sat Nav System) is a system of satellites constellation. In general, it is developed and maintained by a nation that provides geographic positioning. A Sat Nav system is being used to find out the coordinates, altitude, time and velocity of an object presented on the ground. The satellites transmit a signal that holds orbit data and the correct time of signal broadcasted. All the satellites in the constellation to keep synchronization by an atomic clock. Signals coming from several satellites are proceed by the receiver simultaneously so that it can use triangulation (to find out the position of an object with the help of measuring the angles to it from two identified objects) process to find out its position. In the broadcast, the accurate satellite positions are included and the flight's time of the signal is used to compute the distance of all satellite. There are 4 criteria to measures the performance of satellite navigation system shows in Table 1: Table 1: Measuring criteria to measures the performance of satellite navigation system S. No. Measuring criteria Description 1 Precision The difference between the actual position and the calculated position, speed or time of the receiver. 2 Integrity The ability of system to give confidence thresholds with alarms in the occasion that inconsistency produced in the positioning data. 3 Continuity The functional ability of navigation system without obstacle. 4 Availability It refers to which the signal accomplish the precision, integrity and continuity criteria during the time's percentage. A satellite navigation system, which covers the whole globe, is known as Global Navigation Satellite. It refers to a group of satellites that is used to provide signals from the space for broadcasting positioning and timing data, at any place on the earth's surface. Although all of these are military systems as well as available for private and commercial purposes. The functionality of GNSS receiver is to find out the position of an object or area from space with the help of timing and
positioning data converted into the signals. The GNSS consist of 3 main components or segments including (Fig. 1): a) Space segments b) Control segments c) User segments Fig. 1 GNSS Architecture [Source: (Jeffrey C, 2010)] 1.1 Space Segments It is consists of all GNSS satellites in orbit at an altitude of 20,000 km from the ground. All GNSS has its own group of satellites, which are arranged in orbits to the required coverage (Figure 2). There are 24 satellites placed in 6 orbital planes equally and inclined at 55 degree to the equator each orbital plane have 4 satellites with 11 hours and 56 minutes orbital periods. The GPS satellite has 2 solar energy converting panels supplied electrical power that regularly track the Sun and charge 3 batteries for use when the earth eclipses the Sun.
[Source: (Jeffrey C, 2010)] Fig. 2 GNSS Space Segment 1.2 Control Segments It is consists of a ground based network with master control stations, data uplinking stations, command-and-control, satellite path, computation of clock data and monitor stations. The GPS has 2 master control stations including one primary station and one backup station, 4 data uploading stations and 10 monitor stations situated all over the world. In general, the monitoring stations are set up over a large geographic region, track the status, signal of satellite, and transfer this information to the master control stations. These information analyzed by the master control station then relay orbit and time corrections to the satellite by data uploading stations. Fig. 3 GNSS Control Segment [Source: (http://www.gps.gov/systems/gps/control/)]
1.3 User Segments It is most important and ultimate segment of GPS, which is consist of equipment that process the signals received by the GNSS and uses them to get and apply position, time and speed information. The 3 basic components of GPS receivers are: An antenna that collects the radio signal and in other conditions has anti-jamming potential. A receiver -processor unit, that coverts the signal for navigation solution. A display unit, which shows the location's information and gives an interface for receiver control. There are 4 GNSS has being working includes: a) Navigation Satellite Timing and Ranging Global Positioning System (NAVSTAR GPS): It is the most used radio navigation system based on satellite today, which provides accurately 3D (3 dimension) position of a feature on the ground in the form of latitude, longitude and altitude. These information can be collected continuously during the day and night with the help of receiver (GPS instrument). It was the first GNSS, which is completely functioning and launched in the late 1970's. It was developed and maintained by the department of defense and transportation, of the United States of America (USA). The NAVSTAR GPS has capabilities to work in anyweather conditions, space based navigation system to fulfil the needs of the US military and precisely find out their location, velocity and time in a common reference system, any place on or near the Earth on a continuous basis (wooden, 1985). The GPS receivers is used by both the military and civilians to receive, velocity, time, decode and process the signals to get 3D location. The satellites of NAVSTAR GPS are distributed in 6 planes, each in a 12 hours, 20,000 kms high orbit. It broadcast the signals that allow to determine the positions with high precision of special receivers, which can be fixed on ground, moving object, flying object and satellites with low earth orbit. It is used in the areas where accurate positioning is essential like
surveying, navigation, mapping and others applications. In NAVSTAR satellite constellation, each satellite transmits 2 L bands radio signals containing ranging codes, ephemeris parameters and Coordinated Universal Time (UTC) synchronization information. b) Global Orbiting Navigation Satellite System (GLONASS) of Russia: It is a network of Global Navigation Satellite System in an orbit like NAVSTAR GPS of America and GALILEO of Europe, but there is some technical differences among them. GLONASS was developed by the Soviet Union during 1970s and now, it is being operated by the Russian Space Forces. This system uses radio time signals, which is used to position person as well as vehicles available on the ground and above the ground. In 1983, the operational satellite went in service. Russia nonstop building the GLONASS system after the old Soviet Union was disintegrated in 1990s. The GLONASS became completely operation in 1995. In the year 2002, Russia has only 8 GLONASS in operational due to the poor economic condition after the disintegration of Soviet Union. When the economic conditions of Russia was improved, 11 satellites became operational in the year 2004 and total of 14 were in orbit by the end of 2005. GLONASS and U.S. NAVSTAR are works almost similarly such as, it is flying at an altitude of 12 thousand miles from the surface of the earth and broadcasting frequencies on 2 range, 1200 and 1600 MHz GLONASS transmit precision (SP) and high precision (HP) signals at a frequency approximately 1.6 GHz. It offers a standard C/A positioning and timing service with horizontal position accuracy at 55 meters and vertical position accuracy at 70 meters that is based on the measurements from 4 satellites signals. P is more precise signal for Russian military uses. c) GALILEO of Europe: GALILEO is a global navigation satellite system (GNSS) developed and maintained by Europe. In 1994, the GNSS initiatives was started by the European Union. It will offer a highly precise global positioning service under civilian control. On 28th December 2005, the first satellite was launched. Giova A is a 1322-pound satellite went into orbit
14430 miles into the space. In 2010, the next bird 3 of 30 is slated to go up with a full system launched around in 2013. The full system with 30 satellites located in 3 circular Medium Earth Orbit (MEO) planes at 23616 kms above from the ground and at an inclination of 56 degree of the orbital plane with reference to the equator. d) COMPASS of China: China is also started to develop its own navigation satellite known as CNSS (Compass Navigation Satellite System) or Beidou- 2 (Its Chinese name). In 2005, the CNSS was officially started and announced by China in 2006. It will be based on its existing regional Compass Satellite Navigation Experimental System (BeiDou-1). It is not an extension of Beidou-1, but a new GNSS like NAVSTAR GPS of U.S, GLONASS of Russia and GALILEO of Europe. This system will be group of 35 satellites that included five geostationary orbit satellites and thirty MEO satellites with full coverage of the world. The ranging signals of this system are based on Code Division Multiple Access (CDMA) principal. There will be 2 levels of positioning service similar to the other GNSS like open and military. The Sun Jiadong is a general designer of Compass navigation system and also designer of Beidou navigation system. The Compass has 4 frequency bands such as E1, E2, E5B and E6 and overlap with Galileo. As per China National Space Administration (CNSA) and China Satellite Navigation Office (CSNO), the Chinese global navigation system has following 3 development phases. Phase-1: BeiDou Navigation Satellite Demonstration System has been established during 2000-2003 and the experimental BeiDou navigation system included 3 satellites. Phase-2: The regional BeiDou Navigation Satellite system covered China and its neighboring areas in 2012. Whereas in 2014, the system had been ready to offer more accurate positioning and navigation services to the region of Asia-Pacific.
Phase-3: The BeiDou system will be fully established and provide worldwide service by 2020. In Table 2, shows the characteristics of various GNSS system in the world, which has discussed above in details. Table 2: Comparison of various GNSS systems. S. No. System GPS GLONASS Galileo BeiDou 1 Owner U.S.A Russia Europe China 2 Orbital height 20,180 kms 19,130 kms 23,222kms 21,150 kms 3 Time 11 h 58 min 11 h 16 min 14 h 5 min 12 h 38 min 4 No. of satellites 32 (at least 24 by design) 5 Frequency 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal) 28 (at least 24 by design) including: 24 operational 2 under check and 2 in flight test phase 4 in orbit validation satellites +8 full operation capable satellites in orbit and 22 operational satellites budgeted 1.164-1.215 GHz (E5a and E5b), 1.260-1.300 GHz (E6) and 1.559-1.592 GHz (E2-L1- E11) 5 GEO satellites and 30 MEO satellites Approx. 1.602 1.561098 GHz (SP) and GHz (B1), approx. 1.246 1.589742 GHz (SP) GHz (B1-2), 1.20714 GHz (B2) and 1.26852 GHz (B3) 22 satellites operational and 40 additional additional satellites by satellites by 2016-2020. 2016-2020. 6 3 3 3 6 Status Operational Operational 8 satellites operational and 22 7 No. of orbital planes 8 Orbital inclination 55 degree 64.8 degree 56 degree 55 degree 9 Satellite Mass 11000 kg 1400 kg 625 kg 2200 kg 10 Coding scheme CDMA FDMA CDMA CDMA
2. Summary A satellite navigation system (Sat Nav System) is a system of satellites constellation that is developed and maintained by a nation that provides geographic positioning, altitude, time and velocity of an object presented on the ground. A satellite navigation system, which covers the whole globe, is known as Global Navigation Satellite. There are 4 GNSS has being working includes: a) Navigation Satellite Timing and Ranging Global Positioning System (NAVSTAR GPS): It is the most used radio navigation system based on satellite today, which provides accurately 3D (3 dimension) position of a feature on the ground. The satellites of NAVSTAR GPS are distributed in 6 planes, each in a 12 hours, 20,000 kms high orbit. It is used in the areas where accurate positioning is essential like surveying, navigation, mapping and others applications. b) Global Orbiting Navigation Satellite System (GLONASS) of Russia: It is a network of Global Navigation Satellite System in an orbit like NAVSTAR GPS of America and GALILEO of Europe. GLONASS was developed by the Soviet Union during 1970s and now, it is being operated by the Russian Space. It is flying at an altitude of 12 thousand miles from the surface of the earth and broadcasting frequencies on 2 range, 1200 and 1600 MHz GLONASS transmit precision (SP) and high precision (HP) signals at a frequency approximately 1.6 GHz. P is more precise signal for Russian military uses. c) GALILEO of Europe: GALILEO is a global navigation satellite system (GNSS) developed and maintained by Europe. In 1994, the GNSS initiatives was started by the European Union. On 28th December 2005, the first satellite was launched. In 2010, the next bird 3 of 30 is slated to go up with a full system launched around in 2013. The full system with 30 satellites located in 3 circular Medium Earth Orbit (MEO) planes at 23616 kms above
from the ground and at an inclination of 56 degree of the orbital plane with reference to the equator. d) COMPASS of China: China is also started to develop its own navigation satellite known as CNSS (Compass Navigation Satellite System) or Beidou- 2. It will be based on its existing regional Compass Satellite Navigation Experimental System (BeiDou-1). It is not an extension of Beidou-1, but a new GNSS like NAVSTAR GPS of U.S, GLONASS of Russia and GALILEO of Europe. The Compass has 4 frequency bands such as E1, E2, E5B and E6 and overlap with Galileo. Frequently Asked Questions- Q1. What is satellite navigation system (Sat Nav System)? Ans: A satellite navigation system (Sat Nav System) is a system of satellites constellation that is developed and maintained by a nation that provides geographic positioning. A Sat Nav system is being used to find out the coordinates, altitude, time and velocity of an object presented on the ground. Q2. Define Global Navigation Satellite system (GNSS)? Ans: A satellite navigation system, which covers the whole globe, is known as Global Navigation Satellite. It refers to a group of satellites that is used to provide signals from the space for broadcasting positioning and timing data, at any place on the earth's surface.
Q3. What are the main segments of GNSS? Ans: The GNSS consist of 3 main components or segments including: a) Space segments: It is consists of all GNSS satellites in orbit at an altitude of 20,000 km from the ground. There are 24 satellites placed in 6 orbital planes equally and inclined at 55 degree to the equator each orbital plane have 4 satellites with 11 hours and 56 minutes orbital periods. b) Control segments: It is consists of a ground based network with master control stations, data uplinking stations, command-and-control, satellite path, computation of clock data and monitor stations. c) User segments: It is most important and ultimate segment of GPS, which is consist of equipment that process the signals received by the GNSS and uses them to get and apply position, time and speed information. Q4. What are the differences between NAVSTAR GPS and GLONASS? Ans: The differences between NAVSTAR GPS and GLONASS are mention in the table below: S. No. System NAVSTAR GPS GLONASS 1 Owner U.S.A Russia 2 Orbital height 20,180 kms 19,130 kms 3 Time 11 h 58 min 11 h 16 min 4 Coding scheme CDMA FDMA 5 No. of orbit 6 3 6 Orbital inclination 55 degree 64.8 degree
Multiple Choice Questions- 1. What is the full form of GNSS a) Global Navigation Satellite System b) Great Navigation Satellite System c) Great New Satellite System d) Global New Satellite System 2. Which of the following GNSS associated with U.S.A a) GLONASS b) NAVSTAR GPS c) GALILEO d) All of these 3. Which of the following GNSS does not use CDMA coding scheme a) BeiDou b) NAVSTAR GPS c) GLONASS d) GALILEO 4. What is the main function of GNSS a) To determine the position of an object b) To calculate the speed of an object c) Both of these d) None of these 5. Which of the following is not a segment of GNSS a) Space segment b) Satellite segment c) Control segment d) User segment
Suggested Readings: 1. Rahman, A., & Fazal, S. (2017). Global Positioning System: Concept, Technique and Application, 1 st Edn. New Age International Pvt. Ltd, New Delhi. ISBN: 8122440657, 978-8122440652.