Centimeter-accurate Positioning with Handheld GNSS Receiver

Abstract

As a result of advances in technologies, the raw GNSS measurement (i.e., pseudorange, phase, and Doppler) can now be collected with smartphones, tablet computers, and handheld GNSS receivers/chipsets. The most important milestone in this field was undoubtedly Google’s announcement in May 2016 that devices with Android Nougat v.7.x and higher operating systems can collect GNSS raw data. On the other hand, some manufacturers (like Garmin Ltd.) have allowed GNSS raw measurements to be recorded with handheld GNSS devices, which are mostly used for navigation, outdoor and sporting activities. This has paved the way for smartphones or handheld-type GNSS devices to be used as accurate 3D positioning systems in addition to their standard functions. In this study, the 3D positioning performance of the Garmin GPSMAP® 66sr handheld device using the raw measurements is presented. For this purpose, two static test measurements were made, one in a noisy environment without completely open sky visibility and having more multipath effects and the second one in relatively favorable environmental conditions. In these measurements, GPS (L1, L5), GLONASS (L1), and Galileo (E1, E5a) data were collected at 1-second intervals with a Garmin receiver, and the points were coordinated with the conventional relative method and PPP technique. In order to determine the effect of measurement time span on the accuracy performance, the data collected over a longer period were divided into sub-groups of 1-hour each and processed again using the same ways. The coordinates obtained from the Garmin receiver’s solutions were compared with those measured by the geodetic receiver. The overall results show that the handheld GNSS receivers achieved centimeter-level accuracy with the relative technique, while meter-level accuracy could be obtained with the PPP technique.

Full text

http://symp2023.geodesy-union.org/
MODERN TECHNOLOGIES,
EDUCATION AND PROFESSIONAL PRACTICE
IN GEODESY AND RELATED AREAS
XXXIII
INTERNATIONAL
SYMPOSIUM
1-3 November 2023, Sofia, Bulgaria
PROCEEDINGS
ФОНД
НАУЧНИ
ИЗСЛЕДВАНИЯ
МИНИСТЕРСТВО НА ОБРАЗОВАНИЕТО И НАУКАТА

XXXIII INTERNATIONAL SYMPOSIUM
MODERN TECHNOLOGIES, EDUCATION AND
PROFESSIONAL PRACTICE IN GEODESY AND RELATED AREAS
Reports
2023, Sofia, Bulgaria
© Publisher: UNION OF GEODESISTS AND LAND PLANNERS IN BULGARIA
Bulgaria, 1000 Sofia
St. G.S. Rakovski 108
ISSN: 2367-6051

ORGANIZERS
INTERNATIONAL FEDERATION OF SURVEYORS
INTERNATIONAL SOCIETY FOR PHOTOGRAMMETRY AND REMOTE SENSING
EUROPEAN COMMITTEE ON GEODESY
EUROPEAN GROUP OF SURVEYORS
INTERNATIONAL ASSOCIATION OF GEODESY
ISTANBUL TECHNICAL UNIVERSITY
UNION OF SURVEYORS AND LAND PLANNERS IN BULGARIA
FEDERATION OF SCIENTIFIC AND TECHNICAL UNIONS
BULGARIAN ACADEMY OF SCIENCES – NATIONAL INSTITUTE OF GEOPHYSICS, GEODESY AND GEOGRAPHY BULGARIAN
ACADEMY OF SCIENCES – INSTITUTE OF SPACE RESEARCH AND TECHNOLOGY
UNIVERSITY OF ARCHITECTURE, CONSTRUCTION AND GEODESY
MINISTRY OF REGIONAL DEVELOPMENT AND PLANNING - AGENCY FOR GEODESY, CARTOGRAPHY AND CADASTER
MINISTRY OF AGRICULTURE AND FOOD
MINISTRY OF DEFENSE - MILITARY GEOGRAPHIC SERVICE
CHAMBER OF SURVEYING ENGINEERS
ASSOCIATION OF SURVEYING FIRMS
CHAMBER OF ENGINEERS IN INVESTMENT DESIGN - GEODESY SECTION
UNION OF SCIENTISTS IN BULGARIA - SECTIONS OF TECHNICAL AND GEOLOGICAL - GEOGRAPHICAL SCIENCES
ORGANISING COMMITTEE
Start chairman: Prof. Dr. Eng. Georgi Milev
Chairman: Dr. Eng. Ivan Kalchev
Deputy Chairman: Assoc. Dr. Eng. Maria Asenova – science
Deputy Chairman: Assoc. Prof. Dr. Eng. Todor Kostadinov - organization
MEMBERS
Acad. Ph.D. Eng. Yachko Ivanov, NTSSB
Art. Cor. toll. arch. Atanas Kovachev, LTU
Prof. D.T. Eng. Georgi Valev, SGZB
Prof. Andrey Andreev, PhD, Eng
Shumen Prof. Dr. Eng. Elena Peneva, UASG
Prof. Ph.D. Eng. Stanislav Vassilev, UASG
Prof. Dr. Eng. Boyko Rangelov, Moscow State University
Prof. Dr. Eng. Keranka Vasileva, SGZB
Prof. Margarita Mondeshka, UASG
Prof. Dr. Eng. Denitsa Borisova, BAS-IKIT
Prof. Dr. Eng. Hristo Nikolov, BAN-IKIT
Assoc. Dr. Eng. Kostadin Kostadinov, SGZB
Prof. Dr. Eng. Ivan Kunchev, UASG
Prof. Dr. Eng. Veneta Kotseva, SGZB
Assoc. Dr. Eng. Mila Atanasova-Zlatareva, BAS-NIGGG
Assoc. Dr. Eng. Kristina Mikrenska, UASG
Assoc. Ph.D. Eng. Veselina Gospodinova, Moscow State University
Ch. Dobromir Filipov, Ph.D., assistant professor, UASG
Kiril Stoyanov, Ph.D., Eng
Eng. Violeta Koritarova, AGKK
Col. Eng. Ivan Inkovski, VGS
Col. Eng. Svetoslav Tsarovski, VGS
Col. Eng. Nikolay Yordanov, VGS
Eng. Ivan Deyanov, KIIP
Eng. Zlatan Zlatanov, KIG
Eng. Tsvetan Georgiev, AGF
Eng. Tsveten Boev, SGZB
TECHNICAL COMMITTEE
Eng. Ivanka Koleva, SGZB - head Assoc. Dr. Eng.
Assistant Dr. Eng. Nadezhda Yarlovska, UASG
Eng. Stanimira Stoyanova, SGZB
Eng. Margarita Toncheva

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
CENTIMETER-ACCURATE POSITIONING WITH HANDHELD
GNSS RECEIVER
Reha Metin ALKAN, Serdar EROL and Bilal MUTLU
SUMMARY
As a result of advances in technologies, the raw GNSS measurement (i.e., pseudorange, phase, and
Doppler) can now be collected with smartphones, tablet computers, and handheld GNSS
receivers/chipsets. The most important milestone in this field was undoubtedly Google’s
announcement in May 2016 that devices with Android Nougat v.7.x and higher operating systems
can collect GNSS raw data. On the other hand, some manufacturers (like Garmin Ltd.) have allowed
GNSS raw measurements to be recorded with handheld GNSS devices, which are mostly used for
navigation, outdoor and sporting activities. This has paved the way for smartphones or handheld-type
GNSS devices to be used as accurate 3D positioning systems in addition to their standard functions.
In this study, the 3D positioning performance of the Garmin GPSMAP® 66sr handheld device using
the raw measurements is presented. For this purpose, two static test measurements were made, one in
a noisy environment without completely open sky visibility and having more multipath effects and
the second one in relatively favorable environmental conditions. In these measurements, GPS (L1,
L5), GLONASS (L1), and Galileo (E1, E5a) data were collected at 1-second intervals with a Garmin
receiver, and the points were coordinated with the conventional relative method and PPP technique.
In order to determine the effect of measurement time span on the accuracy performance, the data
collected over a longer period were divided into sub-groups of 1-hour each and processed again using
the same ways. The coordinates obtained from the Garmin receiver’s solutions were compared with
those measured by the geodetic receiver. The overall results show that the handheld GNSS receivers
achieved centimeter-level accuracy with the relative technique, while meter-level accuracy could be
obtained with the PPP technique.
KEYWORDS: GNSS, LOW-COST POSITIONING, CENTIMETER-
ACCURATE POSITIONING, PPP, GARMIN GPSMAP 66SR
INTRODUCTION
Global Navigation Satellite System (GNSS) has become the most widely used method in many
different areas as a fast, reliable, robust, and accurate positioning tool. This method can provide the
3D position of a static or moving object in meters, centimeters, and even millimeters level depending
on the used method (i.e., absolute or relative) and the receiver type (number of frequencies, tracked
GNSS constellations, geodetic- or -consumer- type, etc.). In general, it is possible to achieve
meterslevel accuracy with code measurements in absolute mode while at the centimeter or even
millimeterlevel with carrier-phase-based relative method. To make positioning with the first
approach, essentially, a receiver of a few hundred USD is sufficient. On the other hand, for the second
group surveying task, a multi-frequency and multi-constellation geodetic-grade receiver is required,
with prices ranging from 5K USD to 20K USD or more (each). However, the absolute method cannot
provide the accuracy required by many surveying applications. In order to achieve the cm-level
accuracy, a relative solution technique using carrier-phase observations should be used. In the relative
13

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
technique, the point(s) are coordinated from a reference station(s) with precisely known coordinates.
Therefore, this method requires simultaneous observations of satellites with at least two or more
GNSS receivers. This approach also requires GNSS processing software to evaluate the data.
Recent improvements have emerged in some new algorithms and methodologies that allow for high
accuracy (cm-dm) positioning utilizing data obtained with a single GNSS receiver. Precise Point
Positioning (PPP) is the most widely known and used technique in many different applications every
day. With the PPP technique, the 3D position can be determined in static and kinematic modes with
cm-dm accuracy level using the GNSS raw data collected with a single receiver together with the
precise satellite orbits and satellite clock corrections, and code & phase biases and other products
offered by many other analysis centers, especially by the International GNSS Service (IGS)
(Zumberge et al., 1997; Cai et al., 2015; Choy et al., 2017; Duong et al., 2020; Erol et al., 2020;
Akpınar, 2023; Hou and Zhou, 2023).
It should be noted that to obtain high accuracy performance from either the relative positioning
method or the PPP technique (i.e., to determine the position with accuracy in the level of cm to dm),
carrier-phase observations together with the code measurements should be done. However, this
requires the use of at least one geodetic receiver for the PPP technique and at least two geodetic
receivers for the relative method.
On the other hand, the use of low-cost Original Equipment Manufacturers (OEM) type GNSS
receivers has started to use for high accurate positioning. They can be used as single or multifrequency
receivers, allowing code and phase measurements to be logged, and it can also offer an RTK feature.
However, such systems have only been used by certain researchers in certain projects due to the fact
that there are many things users need to do in order to provide connections between components, data
collection, and logging, not having a user-friendly interface and the requirement of developing several
things by the users. More recently, the raw GNSS measurements (i.e., pseudorange, carrier-phase
measurement, Doppler, S/N, and so on) have become possible with smartphones and tablet computers,
and handheld GNSS receivers. Especially, Google announced that devices with Android v.7.0 or later
operating systems could record code and phase measurements, in May 2016. This paved the way for
the use of all devices with an Android operating system, especially smartphones and tablets, in low-
cost high-accuracy positioning studies. Today, many devices, a significant number being
smartphones, are equipped with a GNSS chipset. According to the ′EUSPA EO and GNSS Market
Report 2022‵ prepared by the European Union Agency for the Space Programme (EUSPA), it is stated
that there are around 6 billion GNSS devices used on different platforms (tablets, smartphones, digital
cameras, portable computers, etc.), and that more than 10 billion GNSS devices will be in use
worldwide by 2031 (URL-1). As a note, while the European Commission is supremely responsible
for the Galileo program, EUSPA is responsible for service delivery and market development, as well
as deploying the system and providing technical support for operational tasks. As a result of this
development, billions of smartphones used for communication, navigation, and multi-media
purposes, as well as all other devices with Android operating systems that have GNSS receivers, have
paved the way for their use in geodetic positioning.
When the relevant literature is examined, it is revealed that the accurate-positioning performance of
tablets and smartphones varies depending on the number of frequencies and measurements used
(code/carrier phase), experimental setups, and environmental conditions. While the processing of the
measurements made with the embedded antennas of the devices, especially those based only on code
measurements, yielded accuracies in the order of meters, the use of carrier phase measurements along
14

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
with the pseudoranges significantly increased the accuracy. The best results were obtained with an
external geodetic antenna. This is because the measurements made on such devices are much more
affected by multipath, and the measurements have high noise. According to the studies, the utilization
of Android smart devices equipped with multi-frequency and multi-constellation GNSS chipset used
with an external geodetic antenna achieved an accuracy at the order of cm-dm level in static mode.
However, it is seen that lower accuracies are obtained in kinematic measurements (Håkansson 2019;
Robustelli et al., 2019; Dabove et al., 2020; Heßelbarth and Wanninger, 2020; Wen et al., 2020; Alkan
and Delice, 2021; Hu et al., 2023; Li et al., 2023). Unlike Android-based platforms, OEM-type GNSS
receivers using geodetic antennas provided the resolving of the carrier phase ambiguities and thus
offer cm-dm accuracy in static and kinematic modes (Constantin-Octavian, 2012; Alkan and Delice,
2021; Hamza et al., 2021; Romero-Andrade et al., 2021; Hohensinn et al., 2023).
The number of studies with handheld GNSS receivers has been limited compared to others. As far as
is known, the first academic research based on handheld receivers was conducted by Hill et al. (1999).
El-Mowafy (2005) demonstrated that the decimeter positioning accuracy could be achieved by
processing the data with differential post-mission mode with Garmin handheld GNSS receivers.
However, in these studies, raw GNSS data were not commercially available (were not provided by
the manufacturer) but were obtained through proper software (GRINGO) coded by the researchers.
As one of these studies, Lachapelle et al. (2018.a) conducted a series of measurements with the
Garmin Rino 750 series. However, this device also did not provide the raw GNSS data commercially.
The same year, in 2018, Garmin Ltd. made it possible to collect and record raw GNSS measurements
(pseudorange, carrier phase, and Doppler data) with some models of handheld GNSS receivers. This
made it possible to acquire code and phase measurements with a handheld GNSS receivers, paving
the way for high-accurate positioning with such devices. One of the very limited number of
publications with this device was conducted by Lachapelle et al. (2018.b). They collected the GPS
and Galileo observations in static and kinematic modes with both handheld devices and Android
smartphones. They used an external geodetic antenna throughout the measurement. According to their
processing results, the Garmin device in kinematic mode provided better than 1 m RMSE in all
components. They also concluded that using the external GNSS antenna achieved better results in the
high multipath environment over a helix antenna by reducing the multipath and signal attenuation.
Wanninger et al. (2022) investigated the performance of the Garmin GPSMAP® 66sr handheld-type
GNSS device. They demonstrated that the device provided centimeter-accurate positioning.
The aim of this study is to demonstrate the static positioning performance of the Garmin GPSMAP
66sr handheld GNSS receiver by using pseudorange and carrier phase observations. The collected
GNSS data were processed by both the relative positioning method and the PPP technique.
MATERIALS AND METHODS
Data Collection
To assess the accuracy performance of the Garmin handheld-type GNSS receiver, two realistic field
test measurements were conducted in Istanbul Technical University (ITU) Ayazaga Campus in
Istanbul, Türkiye. Within this scope, two control points were established, and static GNSS
measurements were conducted. Within the scope of the study, in order to reveal the effect of
measurement conditions on positioning performance, the points were installed in two different
15

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
environmental conditions. In this context, the first of the points (CP-1) was established in a location
having multipath conditions under partly limited sky conditions. The second one (CP-2), in contrast
to the first one, was located on the roof of the Civil Engineering Faculty at ITU Ayazaga Campus,
which provides a relatively clear sky observation without signal obstructions and low levels of noise
and a multipath environment (Figure 1).
(a) (b)
Figure 1. The field test measurements; (a) first test, (b) second test
The Garmin GPSMAP 66sr (hereafter also called as 66sr) was introduced by Garmin Ltd. as the first
dual-frequency multi-constellation handheld GNSS receiver with a quadrifilar antenna in 2020
(Wanninger et al. 2022). It observes the GPS (L1, L5), GLONASS (L1), Galileo (E1, E5a) and QZSS
(L1, L5), and IRNSS (NavIC) (L5) satellite signals. The user can choose the satellite system as ′GPS
only‵ for single-frequency positioning and ′Multi-GNSS‵ for multi-frequency positioning. It should
be emphasized that the 66sr has a quad helix antenna. This provides to attenuate the multipath signals
by generating a circularly polarized hemispherical radiation pattern (Wanninger et al., 2022). The
main specification of the 66sr is given in Table 1 (URL-2).
Table 1. Main properties of the Garmin GPSMAP 66sr
16

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
GNSS Constellations
GPS (L1, L5); GLONASS (L1); Galileo (E1, E5a);
QZSS (L1, L5); and IRNSS (NavIC) (L5)
Chipset
BCM47758
Antenna
Quad Helix
RINEX Logging
Internally in version 3.04 format
Dimensions and
Weight
62 x 163 x 35 mm; 230 g
Operating
Temperature
-20 to 60 °C
Battery
Built-in rechargeable lithium-ion and up to
36 hours in default mode
The static GNSS data were collected through the test measurements about 2 hours in the first trial on
09 July 2023 (GPS Day of Year 190) and about 5 hours in the second trial on 10 July 2023 (GPS Day
of Year 191) by tracking all available GPS (L1, L5), GLONASS (L1) and Galileo (E1, E5a) satellites
in view with a 4.5-degree minimum elevation mask angle. The data was collected at a 1-second
sampling rate by default and cannot be changed. It should be noted that, in the first trial, a tripod or a
prism pole was not used, instead the receiver was placed very near to the ground in order to make a
more noisy measurement condition (Figure 1.a). This gives us more information about the
performance of the Garmin receiver in challenging environmental conditions, having high levels of
noise and multipath. At the end of the test measurements, the GNSS raw data was recorded in RINEX
v.3.04 format and transferred from Garmin's internal memory to a PC using a micro-USB port.
The total number of tracked GNSS satellites and corresponding PDOP values were presented in
Figure 2.
17

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
Figure 2. The tracked GNSS satellites and PDOP values for the field tests (up: first test, down:
second test)
In both test measurements, the number of observed satellites was significantly increased compared to
single-satellite systems. On the other hand, it can be seen from Figure 2 that the PDOP values change
inversely with the number of satellites. However, the sudden and sharp changes in the number of
satellites and PDOP values were considered to be due to the antenna that was used.
Data Processing and Numerical Results
The accuracy performance of the Garmin GPSMAP 66sr receiver was evaluated with baseline
solution (i.e., relative method) and PPP technique (i.e., absolute method). For the baseline solution,
one of the nearest IGS continuous reference stations, ISTA (41.104450 N, 29. 019346 E,
147.245m), was used as a reference station. The collected data were processed in static mode using
Trimble Business Center (TBC) commercial software. In the solutions, antenna phase-center
corrections were applied according to the values determined by Wanninger et al. (2022). The CP’s
coordinates were calculated within mm-level and cm-level horizontal and vertical precision,
respectively, by partly fixing the integer ambiguities. On the other hand, whole measurement datasets
were divided into 1-hour sub-measurement groups to determine the relationship between accuracy
and occupation times. The data processing procedure was repeated again for the sub-data group.
As a second processing step, the whole data set and sub-groups were processed using the Canadian
Spatial Reference System-Precise Point Positioning (CSRS-PPP), an online GNSS PPP
postprocessing service, to calculate the PPP-derived static coordinates. The service calculates the
coordinates using precise satellite orbit, clock, and bias corrections in combination with the single or
dual-frequency GPS and GLONASS data. It should be noted that the service only uses GPS and
GLONASS data collected on L1 and L2 frequencies and does not accept other frequencies as well as
Galileo observations. Shortly after the GNSS data in RINEX format collected in static/kinematic
mode is sent via the service’s user-friendly web page, the service calculates the corrected averaged
coordinate (for static mode), the corrected track (for kinematic mode), and other information, such as
graphics, tables, etc. and sends this information to the user’s previously registered e-mail address.
After the modernization of the CSRS-PPP service on 20 October 2020, the PPP solutions became
possible with ambiguity fixed solutions for the GPS satellites (i.e., PPP-AR solution). More
information about the service is available in Banville et al., 2021, and URL-3. As it may be recalled,
GPS (L1 and L5) and GLONASS (L1) data can be collected with 66sr. Since the service is unable to
process the GPS L5 frequency, the PPP coordinates were calculated by processing only GPS-L1 and
GLONASS-L1 data as single-frequency solutions. As is known, single-frequency solutions provide
much lower accuracy than dual/multi-frequency solutions. The processing parameters applied by the
service are given in Table 2.
18

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
Table 2. The processing parameters applied by CSRS-PPP online processing service
PPP-
CSRS-PPP v3
Strategy
PP-PPP
Modes

Observables

Satellite systems
G1+R1
Frequency
Single

Float
-
7.5 degree


Reference frame
ITRF2020
   

NRCan Rapid Products
To make a precise accuracy assessment, needed to establish the known coordinates of the control
points (i.e., CP-1 and CP-2). For this purpose, the CP’s coordinates were calculated with the relative
solution using the same reference stations (ISTA). For this purpose, the GNSS measurements were
made with Trimble R8 geodetic-grade receivers. The static GNSS surveying accuracy of this receiver
is given as 3 mm + 0.5 ppm RMS (for horizontal) and 5 mm + 0.5 ppm RMS (for vertical) for the
fast-static mode (URL-4). Finally, all these coordinates obtained from baseline and PPP solutions in
the static mode were compared with the known values in terms of 2D horizontal and height
components. The results were given in Figure 3.
19

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
(a) (b)
Figure 3. The coordinate differences between calculated and known coordinates for the first
test (a) and second test (b)
Discussion
It was seen from Figure 2 that the usability of the GLONASS and Galileo satellites, together with the
GPS, significantly increased the number of satellites in both trials. This obviously strengthened the
spatial geometry of the observed satellites and contributed significantly to the increase in accuracy.
The results shown in Figure 3 show that the measurements made at the noisier and multipath-exposed
point (see Figure 1.a) were slightly worse than those made in clear-sky conditions, but the relative
solutions of all measurement groups resulted in differences from the known coordinates for 2D
position and height in cm-level. However, as a result of the processing of the 1-hour measurement
groups, the differences were slightly worse than the long-period ones, but the maximum differences
of 7 cm in position and height components were achieved. In general, it is considered that the
collection of data with the device's quadrifilar helix antenna plays a major role in this high
performance. As aforementioned, such antennas provide mitigation of multipath signals.
Looking at the results obtained using the CSRS-PPP service, the results agreed with the known
coordinates within the 2 dm level both in 2D position and height components when the data was
processed through a span of 5 hours. However, when the measurement time was reduced to 1 hour,
the differences reached the order of meters. In the measurement made in a noisy environment, these
differences were found to be in the order of several meters. As explained above, it has been evaluated
that the main reason for this situation was that the CSRS-PPP online service uses GPS (L1, L2) and
GLONASS (L1, L2) signals in the process and the receiver used in the study collected the GPS (L1,
L5) and GLONASS (L1) observations, therefore depending on this, the service produced the
singlefrequency solutions. In this case, especially the effect of unmodelled ionospheric delay may
provide less accurate solutions.
CONCLUSIONS
In this study, the positioning performance of the Garmin GPSMAP 66sr handheld GNSS receiver by
the processing of collected code and carrier-phase observations was investigated, and the usability of
20

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
such devices in geodetic surveying projects was demonstrated. The overall results show that
centimeter-level accuracy in the static mode can be achieved with a relative solution comparable to
those obtained with a geodetic GNSS receiver, especially when long observation times were used.
Unlike the relative solutions, it was concluded that the coordinates could be determined in PPP mode
on the level of decimeters to meters level by the processing of the collected static observations at both
favorable and challenging sites.
Today, in almost all countries of the world, especially surveying engineers and technical staff
belonging to other professions working together with them are intensively using GNSS satellite-based
positioning systems in order to get economical, fast, and accurate positioning. In this context, the low-
cost handheld GNSS devices will be a strong alternative to expensive geodetic-grade receivers and
will reduce the need for them. Considering the cost of these devices (typically a few hundred USD),
it is considered that the cost of field studies will considerably reduce and that they will also impose a
tolerable hardware cost on the project implementers in case of destruction/accident/loss, etc. The use
of such systems in geodetic applications will reduce the need for expensive new geodetic sensors,
thus will reduce the carbon footprint of surveying activities.
ACKNOWLEDGMENTS
The authors would like to thank the NRCan for the Canadian Spatial Reference System-Precise Point
Positioning (CSRS-PPP) online service.
REFERENCES
Akpınar, B. (2023). Positioning Performance of GNSS-PPP and PPP-AR Methods for Determining the Vertical
Displacements. Survey Review, 55:388, pp.68-74. https://doi.org/10.1080/00396265.2021.2010018
Alkan, R.M. and Delice, C. (2021). Recent Advances and Perspectives for Accurate Positioning with Low-cost Smart
Devices. In Proc. on 2nd Intercontinental Geoinformation Days (IGD) (online), Mersin, Turkey, May 5-6, 2021, pp.3235.
Banville, S., Hassen, E., Lamothe, P., Farinaccio, J., Donahue, B., Mireault, Y., Goudarzi, M.A., Collins, P.,
GhoddousiFard, R., and Kamali, O. (2021). Enabling Ambiguity Resolution in CSRS-PPP. Navigation, 68(2), pp.433-
451. https://doi.org/10.1002/navi.423
Cai, C., Gao, Y., Pan, L., and Zhu, J. (2015). Precise Point Positioning with Quad-constellations: GPS, BeiDou,
GLONASS and Galileo. Advances in Space Research, 56(1), pp.133-143. https://doi.org/10.1016/j.asr.2015.04.001
Choy, S., Bisnath, S., and Rizos, C. (2017). Uncovering Common Misconceptions in GNSS Precise Point Positioning and
its Future Prospect. GPS Solutions, 21, pp.13-22. https://doi.org/10.1007/s10291-016-0545-x
Constantin-Octavian, A. (2012). Cost-effective Precise Positioning Using Carrier Phase Navigation-Grade Receiver. In
2012 International Conference on Localization and GNSS, Starnberg, Germany.
https://doi.org/10.1109/ICLGNSS.2012.6253132
Dabove, P., Di Pietra, V,. and Piras, M. (2020). GNSS Positioning Using Mobile Devices with the Android Operating
System. ISPRS International Journal of Geo-Information, 9(4):220. https://doi.org/10.3390/ijgi9040220
Duong, V., Harima, K., Choy, S., Laurichesse, D., and Rizos, C. (2020). Assessing the Performance of Multi-Frequency
GPS, Galileo And Beidou PPP Ambiguity Resolution. Journal of Spatial Science, 65(1), pp.61-78.
https://doi.org/10.1080/14498596.2019.1658652
El-Mowafy, A. (2005). Decimetre Level Mapping Using Differential Phase Measurements of GPS Handheld Receivers.
Survey Review, 38(295), pp.47-57. https://doi.org/10.1179/sre.2005.38.295.47
Erol, S., Alkan, R.M., Ozulu, İ.M. and İlçi, V. (2020). Performance Analysis of Real-Time and Post-Mission Kinematic
Precise Point Positioning in Marine Environments. Geodesy and Geodynamics, 11(6), pp.401-410.
https://doi.org/10.1016/j.geog.2020.09.002
21

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
Håkansson, M. (2019). Characterization of GNSS Observations from a Nexus 9 Android Tablet. GPS Solutions, 23:21.
https://doi.org/10.1007/s10291-018-0818-7
Hamza, V., Stopar, B., and Sterle, O. (2021). Testing the Performance of Multi-Frequency Low-Cost GNSS Receivers
and Antennas. Sensors, 21(6):2029. https://doi.org/10.3390/s21062029
Heßelbarth, A. and Wanninger, L. (2020). Towards Centimeter Accurate Positioning with Smartphones. In 2020
European Navigation Conference (ENC 2020), Dresden, Germany, 22-24 November, 2020.
https://doi.org/10.23919/ENC48637.2020.9317392
Hill, C.J., Moore, T., and Dumville, M. (1999). GRINGO A RINEX Logger for Hand-held GPS Receivers. In Proceedings
of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999),
Nashville, TN, USA, September 1999, pp.1647-1652.
Hohensinn, R., Stauffer, R., Glaner, M.F., Pinzón, I.D.H., Vuadens, E., Rossi, Y., Clinton, J., and Rothacher, M. (2023).
Low-Cost GNSS and Real-Time PPP: Assessing the Precision of the u-blox ZED-F9P for Kinematic Monitoring
Applications. Remote Sensing, 14(20):5100. https://doi.org/10.3390/rs14205100
Hou, Z., and Zhou, F. (2023). Assessing the Performance of Precise Point Positioning (PPP) with the Fully Serviceable
Multi-GNSS Constellations: GPS, BDS-3, and Galileo. Remote Sensing, 15(3):807. https://doi.org/10.3390/rs15030807
Hu, J., Yi, D., and Bisnath, S.A. (2023). Comprehensive Analysis of Smartphone GNSS Range Errors in Realistic
Environments. Sensors, 23(3):1631. https://doi.org/10.3390/s23031631
Lachapelle, G., Gratton, P., Horrelt, J., and Lemieux, E. (2018.a). Performance Assessment of a Low Cost Hand Held
GNSS Receiver’s Raw Code and Carrier Phase Data. In Proceedings of the 16th World Congress of the International
Association of Institutes of Navigation, Tokyo, Japan, 28 November-1 December 2018.
Lachapelle, G., Gratton, P., Horrelt, J., Lemieux, E., and Broumandan, A. (2018.b). Evaluation of a Low Cost Hand Held
Unit with GNSS Raw Data Capability and Comparison with an Android Smartphone. Sensors, 18(12):4185.
https://doi.org/10.3390/s18124185
Li, M., Huang, T., Li, W., Zhao, Q., and Jiang, K. (2023). Precise Point Positioning with Mixed Single- and
DualFrequency GNSS Observations from Android Smartphones Considering Code-Carrier Inconsistency. Advances in
Space Research. https://doi.org/10.1016/j.asr.2023.07.042 .
Robustelli, U., Baiocchi, V., and Pugliano, G. (2019). Assessment of Dual Frequency GNSS Observations from a Xiaomi
Mi 8 Android Smartphone and Positioning Performance Analysis. Electronics, 8(1):91.
https://doi.org/10.3390/electronics8010091
Romero-Andrade, R., Trejo-Soto, M.E., Vega-Ayala, A., Hernández-Andrade, D., Vázquez-Ontiveros, J.R., and Sharma,
G. (2021). Positioning Evaluation of Single and Dual-Frequency Low-Cost GNSS Receivers Signals Using PPP and Static
Relative Methods in Urban Areas. Applied Sciences, 11(22):10642. https://doi.org/10.3390/app112210642
Wanninger, L., Heßelbarth, A., and Frevert, V. (2022). Garmin GPSMAP 66sr: Assessment of Its GNSS Observations
and Centimeter-Accurate Positioning. Sensors, 22(5):1964. https://doi.org/10.3390/s22051964
Wen, Q., Geng, J., Li, G., and Guo, J. (2020). Precise Point Positioning with Ambiguity Resolution Using an External
Survey-Grade Antenna Enhanced Dual-Frequency Android GNSS Data. Measurement, 157:107634.
https://doi.org/10.1016/j.measurement.2020.107634
Zumberge, J.F., Heflin, M.B., Jefferson, D.C., Watkins, M.M., and Webb, F.H. (1997). Precise Point Positioning for the
Efficient and Robust Analysis of GPS Data from Large Networks. Journal of Geophys. Research, 102 (B3), pp.50055017.
https://doi.org/10.1029/96JB03860
URL-1. EUSPA EO and GNSS Market Report 2022, Issue 1, https://www.euspa.europa.eu (last accessed July 23, 2023).
URL-2. GPSMAP® 66sr Multi-Band GPS Handheld with Sensors and Topo Maps Specs,
https://www.garmin.com/enUS/p/707627#specs (last accessed July 23, 2023).
URL-3. Precise Point Positioning, https://webapp.csrs-scrs.nrcan-rncan.gc.ca/geod/tools-outils/ppp.php (last accessed
July 23, 2023).
URL-4. Trimble R8 GNSS System Datasheet, https://geospatial.trimble.com (last accessed July 23, 2023).
22

XXXIII INTERNATIONAL SYMPOSIUM ON
MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN
GEODESY AND RELATED FIELDS
Sofia, 01 – 03 November 2023
AFFILIATIONS
Prof.Dr. Reha Metin ALKAN, Istanbul Technical University, Faculty of Civil Engineering,
Geomatics Eng. Department Maslak TR- 34469, İstanbul/TÜRKİYE
+90 (212) 285 6564, alkanr@itu.edu.tr
Prof.Dr. Serdar EROL, Istanbul Technical University, Faculty of Civil Engineering,
Geomatics Eng. Department Maslak TR-34469, İstanbul/TÜRKİYE
+90 (212) 285 3826, erol@itu.edu.tr
Res.Asst. Bilal MUTLU, Istanbul Technical University, Faculty of Civil Engineering,
Geomatics Eng. Department Maslak TR-34469, İstanbul/TÜRKİYE
+90 (212) 285 3826, mutlubil@itu.edu.tr
23