1. Utilisation of GNSS for Monitoring Processes
UTILISATION OF GNSS FOR MONITORING PROCESSES :
A PROJECT MANAGER’S PERSPECTIVE
Velan Shanmuga V1
, Chakravarty D1
, Chakrabarti P P2
1
Department of Mining Engineering, Indian Institute of Technology Kharagpur, 721302, India
2
Department of Computer Science & Engineering, Indian Institute of Technology Kharagpur, 721302, India
Abstract: This paper presents the advantages of using Global Navigation Satellite System (GNSS) for
monitoring of projects. GNSS is one of the most suitable technologies for monitoring. Latest developments in
GNSS have increased this suitability. Nine critical factors that are to be considered by the project managers
have been selected and analysed. Contrary to general belief, accuracy of the GNSS and their receivers are
not constant world over. Each system is optimized for the country or region of its origin and cannot be used
directly over the Indian region. The errors also keep varying in the time domain. The solution should not be
used when GDOP is optimum. The augmentation system increases accuracy but the selection of the type
should be ‘deliberate’ and only suitable system should be: if more than one source of augmentation is
available. While using Differential GNSS inputs, accurate and correct positioning of pivot station is vital. The
developers of the IT solution are supposed to have in-depth knowledge on GNSS, else, there is a possibility
that the developer might naught the GNSS input altogether. It is also better to use Multiple GNSS to overcome
the issues of GDOP and satellite availability. A good understanding of the key factors mentioned will enable
better project management.
Key Words: project management, monitoring processes, GNSS, GPS, monitoring solutions
1 Introduction
Monitoring processes group integrates all other process and is considered as the ‘background’
process group [12]. It involves continuous tracking and evaluation of the project against the timelines. Global
Navigation Satellite System (GNSS), better known by the US implementation Global Positioning System
(GPS), provides us a good method for such monitoring. Its applications and usefulness in monitoring various
projects is well documented [1]. Further, the completion of the GPS modernisation programme in 2010 [13]
has given a compelling reason for the project managers to adopt GNSS based monitoring solutions in their
projects. However, while adopting this, care should be taken to understand the nuances of the GNSS
technology; else the effort will become counterproductive.
There are a number of parameters like required positional accuracy, Geometric Dilution of Precision
(GDOP), No of satellites and algorithms used that affect the overall output of the GNSS solution. Also, there
are systems and services, other than the primary system like, augmentation services, differential services, and
other GNSS systems. A good understanding of these issues will help the project manager to implement the
project successfully in shortest possible time. These aspects are analysed in this paper.
2 Brief description on GNSS and constellations
GNSS consists of a set of satellites that circle the globe in medium earth orbits. The position and the
orbit of the satellites are chosen such a way that any user in any location on earth should be able to receive
the signals of desired quality. The system consists of space segment, user segment and control segment.
Space segment encompasses the satellites and their support network, user segment includes the receivers,
users and user applications and the control segment consists of a worldwide network of monitoring and
control stations. The constellation provides an easy means of locating user position on earth using low cost
receiver equipment.

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Utilisation of GNSS for Monitoring Processes
GPS is the oldest GNSS that is being maintained by USA. Apart from it, there are GLONASS of
Russia, Beidou of China and Galileo of EU. Japan has a regional system called MSAS. India has plans to
establish Indian Regional Navigation Satellite Systems (IRNSS) and launched the first satellite IRNSS 1
satellite recently [10].
Apart from the primary systems mentioned in earlier paragraph, there are satellite based
augmentation systems (SBAS). Augmentation systems to GPS are available around the world and are being
used for civil aviation by International Civil Aviation Organisation (ICAO). It consists of Wide Area
Augmentation System (WAAS) of USA, European Galileo Navigation Overlay System (EGNOS) of EU, GPS
Aided Geo Augmented Navigation (GAGAN) of India and Multipurpose Transportation Satellite (MTSAT)
Augmentation System (MSAS) of Japan. These systems have satellites that are geo-stationary and transmit
signals like GPS satellites. They also transmit error correction parameters that the receivers use to correctly
predict the user location. GAGAN is at present in the ICAO acceptance and certification stage.
3 Advantages of using GNSS for Monitoring
The project management body of knowledge (PMBOK) lays down a series of processes to monitor a
project. There are many methods / means of monitoring to support these processes. Most of them are active
and has human element in the chain. On analyzing all available systems / methods and observing their
implementation in various projects over the past decade, the authors have observed that amongst these, the
GNSS is the most suitable for monitoring purposes. It enables continuous tracking of elements within the
project in real time. The below listed nine critical factors provide a distinct advantage to GNSS:-
(a) Most of the services of the GNSS constellation are free; providing one of the most cost effective
tools for the project manager.
(b) The coverage is global, that is GNSS can be used irrespective of the size and geographic
spread of the project. It also provides a means to scale up operations with no additional cost.
(c) The services are available all round the clock, continuously, that is, there is no break in the
services being provided by the system.
(d) The satellite constellation is maintained by a sophisticated support network spread around the
world, which ensures accurate inputs to the user. In most of the other systems, the user has to
maintain the system.
(e) Present day receivers are small and compact enabling their easy placement over vehicles and
premises. They operate passively which enable their integration with any equipment provided
the required signals are available.
(f) The GNSS signal power and structure is so designed that they do not interfere with other
devices.
4 Improvements in GNSS constellations
The latest improvements in the GNSS field have made the advantages mentioned in the previous
section even more attractive for the project managers. GPS which is the oldest system has been upgraded
over a period of time and its accuracy has been increased. Table1 below gives the detailed improvements on
accuracy that have occurred over a period of time on the standard positioning service [11]. From the table it is
evident that the user can fix his position within 8.5 m from 2006 onwards, without any external processing.
This has opened up newer possibilities for applications [1].
Table 1. Effect of GPS Modernisation on the Errors [11]

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Utilisation of GNSS for Monitoring Processes
S.
No.
Error Source With SA
(m)
Without
SA
(m)
Code on L2
and/or L5
(m)
With A-II
a
(m)
1 Selective Availability (SA) 24.0 0.0 0.0 0.0
2 Ionosphere 7.0 7.0 0.01 0.01
3 Troposphere 2.0 0.2 0.2 0.2
4 Orbit and Clock 2.3 2.3 2.3 1.25
5 Receiver Noise 0.6 0.6 0.6 0.6
6 Multipath 1.5 1.5 1.5 1.5
7 User Equivalent Range Error (UERE) 25.0 7.5 2.8 2.0
8 Horizontal Dilution of Precision (HDOP) 1.5 1.5 1.5 1.5
9 Standalone horizontal accuracy, 95%
confidence
75.0 22.5 8.5 6.0
10 Implementation Date May 2,
2000
2003-06 2005-10
GLONASS which became dysfunctional due to the breakup of USSR has been restored to its full
functional state by Mar 2013 [5]. China had published the Interface Connection Document (ICD) [3] for Beidou
on 27 Dec 2012, thereby announcing that Biedou system is fully functional. The Galileo system has moved to
In Orbit Validation (IOV) stage and there is one satellite per orbit and the signals are available for analysis.
GAGAN satellites have been launched and it is in the final approval stage at present. GAGAN signal are
available for users. MSAS is fully functional with the launch of its MSAS 2 satellite on 18 Feb 2006 [7].
When all these systems are fully in place, there will be more than 150 satellites giving helping in
navigation world over. Figure 1 gives the coverage of all navigation satellites when all constellations are fully
functional [2]. From this it is evident that India will stand to gain the maximum as the coverage is nearly the
highest.
Figure 1. Average number of satellite coverage of all planned constellations [2]
5 Factors to be considered

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Utilisation of GNSS for Monitoring Processes
It may be noted that the magnitude of the errors stated at table 1 in respect of the sources are not
constant. The errors keep varying continuously since all or most of the satellites of the constellation keep
moving with respect to the user. Also, there other factors those are beyond the satellite constellation that
influences the overall performance of the system. Project managers need to have good understanding of the
following critical and important factors:-
(a) Ionospheric effect on accuracy.
(b) No of satellites visible.
(c) Dilution of Precision (DOP).
(d) Multipath and Tunneling.
(e) Augmentation Systems.
(f) Differential Systems.
(g) Multi GNSS Systems.
(h) IT Solution Provider’s knowledge.
(i) Understanding of GNSS by the stake holders.
Ionospheric influence on Accuracy. Contrary to general belief, accuracy of the GNSS and their
receivers are not constant world over. Each system is optimized for the country or region of its origin and
cannot be used directly over other region. Over the Indian region the Ionospheric errors influence the
accuracy greatly since it is in the region of maximum ionospheric disturbances as seen from figure 2 [9].
The Ionospheric error correction model presented by Klobuchar (1987) [6] is good for higher latitudes
but no so in the tropical region [8]. In the lower latitudes, the ionospheric activity increases from morning to
mid-day and reduces during the later part. The zone of activity also depends on the direction of the sun.
Hence one solution–compensation model cannot be made for a region or country. The night time activity is
greatly influenced by solar maxima [9]. Study by Meriwether et al [9] in Brazil shows prolonged periods of total
loss of signals in the night. The solar maxima affect both directly and indirectly the GPS satellites since they
produce ionospheric storms and magnetic storms [11].
Number of Satellites Visible. The GNSS positioning techniques primarily use trilateration technique.
For this there is a requirement of having inputs from three satellites. However to cater for receiver clock bias
and height reading, five satellites are required to be visible to the user. Reading the corollary, it will be evident
that if less than five satellites are used then the resultant positional data will not be correct. Availability of more
than five satellites is very less over a specific area. Project managers should have alternate means of finding
position when less than five satellites are visible. For many applications or functionalities, availability of four
satellites may be adequate. To obviate periods of non-availability, modern day receivers take inputs from
more than one constellation; most popular is the GPS and GLONASS combination

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Utilisation of GNSS for Monitoring Processes
Figure 2. Scintillation map showing frequency of disturbances during solar maximum [9]
DOP - Geometry of the Satellites. The availability of the satellites alone will not assure accurate
positional calculations. These satellites should also be in certain geometric dispersion over the receiver. This
aspect given in a measurable quantity called GDOP should be less than 3 for most of the monitoring
applications. The dilution of precision over a region can be predicted and during these times, that specific
constellation should not be used. The geometric dispersion will be higher if satellites from different GNSS
constellation are used. The table 2 below gives the Optimal GDOP values [4]
Table 2. Optimal GDOP values for applications [4]
DOP
Value
Rating Description
1 Ideal
This is the highest possible confidence level to be used for applications demanding
the highest possible precision at all times.
1-2 Excellent
At this confidence level, positional measurements are considered accurate enough
to meet all but the most sensitive applications.
2-5 Good
Represents a level that marks the minimum appropriate for making business
decisions. Positional measurements could be used to make reliable in-route
navigation suggestions to the user.
5-10 Moderate
Positional measurements could be used for calculations, but the fix quality could
still be improved. A more open view of the sky is recommended.
10-20 Fair
Represents a low confidence level. Positional measurements should be discarded
or used only to indicate a very rough estimate of the current location.
>20 Poor
At this level, measurements are inaccurate by as much as 300 meters with a 6
meter accurate device (50 DOP × 6 meters) and should be discarded.
Multipath and Tunneling. In many construction projects such as building of dams, the project area
is closed by natural high raises likes mountains or by artificial high rises like buildings. The position of the user
is calculated from the distance he is from the satellite, which in turn is measured by the distance travelled by
the signal. The high raises around the project site reflect the signals and the receiver uses the reflected signal
to calculate the position. Since the distance travelled by the reflected wave is more than the direct distance,
the position calculated becomes in correct. There are regions within the project site that are covered by
foliage, tunnels etc. where the GNSS signals do not reach altogether. A project manager should have the site

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Utilisation of GNSS for Monitoring Processes
validated for these reflections and tunnels, and the positional data received from these locations should be
assumed to have errors and alternate means have to be catered for. One example of alternate method in a
dam construction site is to have a traffic control personal standing at the start or end of the road that runs in
the reflection or tunnel zone, who feeds the details about the trucks that cross him.
Augmentation Systems. In India, though GAGAN is for the civil aviation and is managed by Airports
Authority of India, the signals are available for anyone to use within the Indian subcontinent. GAGAN has
been planned to improve the GPS accuracy to 2 m from the base 6 m. In the study conducted by the authors,
it has been observed to give positional accuracy of about 2.5 m over Indian Institute of Technology
Kharagpur. Hence, the project managers while using GNSS based monitoring over Indian region should insist
on using latest receivers that use GAGAN signals.
In developed countries, there is more than one system of augmentation. For example in Continental
America (CONAM) there are WAAS and Wide Area Differential GPS Systems (WADGPS) available. Each has
its own advantages and shortcomings. These have to be understood and that system which gives maximum
advantage in a particular area has to be used. In some regions more than one system of augmentation
satellites signal may be available. For example over the Middle-East countries both GAGAN and EGNOS
signals will be available. Over the eastern India both GAGAN and MSAS signals are available. In this
situation, only that system which is designed to give better accuracy over that particular region should be
used.
Differential Systems. In some of the projects, differential systems are used in addition to the
augmentation systems. In this, there is a base reference station whose position has been determined with
very high precision. The GNSS error over this position is continuously monitored and the errors or offsets are
considered to be valid for all receivers that operate around this base station. The error is transmitted in real-
time over a particular frequency and the receivers use the error correction data to give better accurate
positioning. But in actuality, since the project areas are generally new areas or remote areas, there is no pre-
surveyed accurate point nearby. In this condition a suitable vantage point has to be selected for establishing
the base station. This vantage point should be visible to all receivers that operate over the area. The
positional data of this point should be interpolated from the base triangulation stations maintained by Survey
of India. Care should be taken to get deduce the location with highest precision possible.
Multi GNSS Systems. As seen earlier, apart from GPS, the GLONASS and Beidou are fully
functional from Mar 2013. These systems also should be used for monitoring purposes. There is an
agreement between GPS and GLONASS, due to which GLONASS now transmits, in addition to its signals,
Code Division Multiple Access (CDMA) signals like GPS satellites for better compatibility. GPS/GLONASS
dual system receivers are freely available around the world. Project managers should insist on using multi
systems in their solutions as this gives specific advantages as listed below:-
(a) The availability of satellites for calculating position increase greatly.
(b) When the dilution of precision in one system is high, the other can be used without break in
service.
(c) The dilution of precision between the satellites of different systems is very less, since satellites in
different orbits inherently have better geometry.
(d) By using two different transmission bands, the ionospheric delay can be reduced.
India has an agreement with Russia for use of GLONASS signals. Through this agreement, Russian
government has assured availability of GLONASS signals over India. Extending the agreement between
GLONASS and GPS, over Indian region these two systems will be available without disruption. This can be
exploited by the project managers.

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Utilisation of GNSS for Monitoring Processes
IT Solution Provider’s knowledge. In one of the GNSS based monitoring projects that was studied
by the authors, it was observed that the system was giving more than 100 m inaccuracy though very good
quality receivers have been used on board the vehicles. On investigation, it was found that high accuracy
positional data was being transmitted and received at the control station. However, the software that updates
the database truncates the received data while updating the database. This is so because the database
designer did not cater for the acceptance of geo data which generally has 10 digits for longitude and 10 for
latitude. Further investigation revealed that the solution development team did not have any idea about
GNSS. Since the inaccuracies were higher, the users had practically stopped using the GNSS inputs in
monitoring the project. This brings out the importance of scrutinizing the developers and coders who are
involved in the solution development at the project planning stage.
Understanding of GNSS by all stake holders. The essence of project management is “the
alignment of the project with stakeholders’ needs or objectives” [11]. They have the powers to influence the
direction in which the project moves. The stakeholders are the source of capital for the project. The
importance of stake holders management is seen by the fact that Guide to PMBOK dedicates one full chapter
to this aspect. Hence it is essential that the stake holders also be appraised about the nuances of GNSS. In
one of the resource quality monitoring processes of steel mine, studied by the authors, it was observed that
the geologist recording the resource sample’s location, was taking GPS readings even though the satellite
availability was just three. He did not check the availability factor before setting out for collection of samples.
This resulted in wrong evaluation and the ore blending machine was creating trouble the next day. Hence, it is
also essential that all staff involved in the monitoring processes should be sensitized about the key factors
especially the GDOP and satellite availability parameters.
Therefore, from the above analysis and discussion it is evident that the project managers should
understand the sources of errors and strive to reduce them in order to increase the accuracy of positioning,
constrained by the computation time and update frequency. Amongst the factors mentioned above, the project
managers have control over the type of GNSS to be used, the augmentation to be used and the identifying the
time period over which it is not to be used. These should be incorporated in the monitoring processes properly
to achieve the required goals of monitoring processes. The other parameters are also critical but are beyond
the scope of the present considerations because these need different algorithms to control the involved
inaccuracies; whereas, it is considered that these three parameters form the key components to increase the
performance of the monitoring processes.
6 Conclusion
As noted in section 3 above, GNSS has many advantages that make it the most suited technique for
monitoring of the projects. The improvements in GNSS in recent times have made these advantages more
lucrative for the project managers. While using GNSS for monitoring purposes, the project managers should
take note of nine key factors mentioned at section 5 that are associated with the GNSS and the GNSS
technology. They should develop deep understanding of the issues and should also educate all stake holders
regarding the same. The involved staff members should be especially made aware of GDOP and availability
issues. The coverage factor brought out in multipath and tunneling section, should be considered at the
project planning stage itself and alternate means should be planned to overcome these difficulties. A good
understanding of these key factors will enable better utilisation of GNSS technology which in turn will lead to
close monitoring of project and will enable its completion in time, i.e., achieve the desired targets.
References
(1) Ahmed El-Rabbany, 2006, Introduction to GPS, Second Edition, Artech House, pp 139 – 160.

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Utilisation of GNSS for Monitoring Processes
(2) Andrew G Dempster, Chris Rizos, 2009, Implications of A “System of Systems” Receiver.
(3) BeiDou Navigation Satellite System, Signal In Space Interface Control Document (Test
Version), China Satellite Navigation Office, released on 27 Dec 2013.
(4) GDOP, Wikipedia, website http://en.wikipedia.org/wiki/Dilution_of_precision, accessed on 13
Jul 2013 at 0025hrs.
(5) GLONASS Constellation Status, Federal Space Agency, Information-Analytical Centre,
website, http://ftp.glonass-ianc.rsa.ru/ accessed on 14 Mar 2013.
(6) Klobuchar, J.A., 1987, Ionospheric Time-Delay Algorithm for Single-Frequency GPS Users,
Aerospace and Electronic Systems, IEEE Transactions on, vol. AES-23, no. 3, pp. 325,331.
(7) Latest News, Inside GNSS, Mar 2006 issue.
(8) Meriwether, J. W., J. J. Makela, Y. Huang, D. J. Fisher, R. A. Buriti, A. F. Medeiros, and H.
Takahashi, 2011, Climatology of the nighttime equatorial thermospheric winds and
temperatures over Brazil near solar minimum, Journal of Geophysical Resources, 116.
(9) Paul M. K., Jr, Cornell University, Todd Humpreys, The university of Texas at Austin, Joanna
Hinks, Cornell University, 2009, GNSS and Ionospheric Scintillations: How to survive the next
solar maxima, Inside GNSS, July/August 2009, pp 22-30.
(10) Press release by ISRO, Jul 02 2013, PSLV-C22 Successfully Launches IRNSS-1A, India's
First Navigation Satellite, ISRO website, www.isro.org, accessed on 13 Jul 2013.
(11) Project Management International, 2013, A Guide to Project Management Body of Knowledge,
fifth edition, Chapter 2, pp 30.
(12) Project Management International, 2013, A Guide to Project Management Body of Knowledge,
fifth edition, Chapter 3, pp 50.
(13) Shaw, M., Sandhoo, K., and Turner, D., 2000, Modernisation of the Global Positioning System,
GPS World, September 01, 2000, pp36-44.
Authors’ Profile
V Shanmuga Velan, is a retd army officer who had executed many projects in GIS and GNSS during his
service from Jun 2003 till Nov 2011. He was part of the Integrated Space Cell of MoD looking after the
GNSS applications. He is now pursuing research in the broad area of ‘GNSS Based Monitoring’ at
Indian Institute of Technology Kharagpur. He can be contacted at Department of Mining Engineering,
IIT Kharagpur, Kharagpur, 721302, Mob: +91 9564168932, mail: velan_vs@yahoo.co.in. His web page
at IIT Kharagpur is http://www.dak.iitkgp.ernet.in/phd/profile.php?roll=11MI91S01 .
Dr D Chakravarthy, is Associate Professor in the Department of Mining Engineering in Indian Institute of
Technology Kharagpur. He teaches GPS and GNSS subjects apart from other mining engineering
related subjects. He has executed many GNSS research and consultancy projects for the mining
industry. He can be contacted at Department of Mining Engineering, IIT Kharagpur, Kharagpur, 721302,
Tele: +91 3222 283708, mail: dc@mining.iitkgp.ernet.in His web page at IIT Kharagpur is
http://www.iitkgp.ac.in/fac-profiles/showprofile.php?empcode=bUmVT&depts_name=MI.
Dr P P Chakrabarti, is Senior Professor in the Computer Science and Engineering Department
Engineering in Indian Institute of Technology Kharagpur. He is a subject matter expert in Artificial
Intelligence. He is the receiver of different academic awards of national and international repute. He
served as various academic committee heads as well as different administrative heads within and
outside the institute. He has been instrumental in executing numerous research and consultancy
projects for national and international clients through SRIC. At present there are several projects being
executed by the SRIC at IIT Kharagpur. He can be contacted at Department of Computer Science and

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Utilisation of GNSS for Monitoring Processes
Engineering, IIT Kharagpur, Kharagpur, 721302, Tele: +91 3222 283466, mail:
ppchak@cse.iitkgp.ernet.in