You have GPS tracking requirements in areas such as autonomous vehicles, robotics or precision farming, but realize that phones are not accurate enough. You also wish Google Maps and OpenStreetMap had a way higher zoom level. What are your options? Join me on this fast-paced journey as we look at the various options to achieve centimeter-level GNSS accuracy. We’ll look at (affordable) hardware options, such as the dual-frequency GNSS support in the latest generation of phones, as well Arduino-powered base station/rover solutions for your own IoT needs. We venture into Java connectivity options in order to integrate devices via Bluetooth and USB into Spring Boot applications, and show how to process NMEA messages using Spring Integration. Ultimately, we’ll dive into the wider GIS world, briefly touching on QGIS to create base maps, geospatial data persistence options, and how to visually present the end product to your users using Leaflet.js.

1. High-Precision GPS Positioning
for Spring Developers
@GHILLERTGUNNAR HILLERT

2. About ME
▸ Independent Software Developer
▸ Java Champion
▸ DevNexus Co-Founder
▸ OSS Committer
▸ Spring Integration, XD, Data Flow,
Java Marine API
▸ Plant Collector
2Hillert Inc.

3. Contents
▸ Fundamentals
▸ Hardware
▸ Processing of positioning data
▸ Visualization
▸ 2 Demos
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4. Why High Precision GPS?
▸ Autonomous vehicles
▸ Robotics
▸ Precision farming
▸ Drone operation
▸ Infrastructure, Biodiversity etc.
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5. Global Navigation Satellite System (GNSS) refers to a
constellation of satellites providing signals from space that
transmit positioning and timing data to GNSS receivers. The
receivers then use this data to determine location.
European Global Navigation Satellite Systems Agency
GNSS Defined
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6. ▸ GPS (USA)
▸ GLONASS (Russia)
▸ BeiDou (China)
▸ Galileo (EU)
▸ Satellite-based augmentation systems, e.g. QZSS (Japan), EGNOS (EU)
GNSS Systems
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7. Dual Frequency GNSS
▸ L1+L5 (GPS), E1+E5a (Galileo)
▸ “Dual-frequency GNSS on Android devices” by Sean Barbeau
▸ US Device support in 2020 is still spotty
▸ Check phone support with the OSS app GPSTest (Android)
▸ My own experience: better but not amazing (OnePlus 8 Pro)
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8. GNSS Accuracy Compared
OnePlus One
OnePlus 8 Pro
U-Blox
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9. We Can Do Better With Correction Data
▸ Incorporating correction data is key!
▸ Real Time Kinematic (RTK) positioning
▸ Rover + Base Station
▸ Base station should see the same errors (10-40km)
▸ Other correction services exist, e.g. PPP-RTK, PPP
▸ Relative Accuracy versus Absolute Accuracy
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10. How To Consume Correction Data?
▸ NTRIP == RTK over the internet
▸ Eliminates the need for base station
▸ Networked Transport of RTCM via Internet Protocol
▸ RTCM == Radio Technical Commission for Maritime
▸ Manually post-process receiver data
▸ Continuously Operating Reference Stations (CORS)
▸ E.g. using RTKLIB
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11. ▸ Base Station + Rover
▸ Relatively Low Cost
▸ u-blox ZED-F9P module
▸ Bluetooth + Serial
▸
My Setup Base Station Rover
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12. Android
▸ Lefebure NTRIP Client
▸ Connect to external GNSS device via Bluetooth
▸ Enable Mock Locations in Android
▸ Under Developer Options
▸ "Fix type” RTK provides highest accuracy
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What About IoS?
▸ Very limited support
▸ Cannot override GPS
▸ Need custom app integration
▸ Processing of NMEA data via WIFI
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▸ NMEA 0183
▸ National Marine Electronics Association
▸ Proprietary “Standard”
▸ Text based
▸ Numerous sentence (message) types
▸ Why GPSes suck, and what to do about it
▸ Alternative: Proprietary Binary Formats
How to Process GNSS Data? $GNRMC,024429.00,A,1939.4742123,N,15556.999
$GNVTG,,T,,M,0.027,N,0.050,K,A*3D
$GNGGA,024429.00,1939.4742123,N,15556.99941
$GNGSA,A,3,01,07,03,11,22,,,,,,,,2.13,1.02,
$GNGSA,A,3,81,68,78,,,,,,,,,,2.13,1.02,1.87
$GNGSA,A,3,02,,,,,,,,,,,,2.13,1.02,1.87,3*0
$GNGSA,A,3,,,,,,,,,,,,,2.13,1.02,1.87,4*09
$GPGSV,2,1,05,01,58,154,45,03,49,030,33,07,
$GPGSV,2,2,05,22,46,064,32,1*50
$GPGSV,2,1,05,01,58,154,41,03,49,030,32,07,
$GPGSV,2,2,05,22,46,064,,6*56
$GLGSV,3,1,10,66,19,040,21,67,34,344,29,68,
$GLGSV,3,2,10,77,36,112,,78,15,167,34,81,41
$GLGSV,3,3,10,83,17,326,,88,02,169,29,1*74
$GLGSV,3,1,10,66,19,040,14,67,34,344,26,68,
$GLGSV,3,2,10,77,36,112,20,78,15,167,38,81,
$GLGSV,3,3,10,83,17,326,,88,02,169,33,3*7D
$GAGSV,2,1,07,02,22,138,40,05,02,059,,07,12
$GAGSV,2,2,07,15,,,35,18,29,218,38,25,18,08
$GAGSV,2,1,06,02,22,138,30,05,02,059,,07,12
$GAGSV,2,2,06,18,29,218,30,25,18,085,,2*79
$GBGSV,1,1,00,*47
$GBGSV,1,1,00,*47
$GNGLL,1939.4742123,N,15556.9994168,W,02442
$PUBX,00,024429.00,1939.4742123,N,15556.999
$PUBX,03,22,1,U,154,58,45,064,3,U,030,49,33
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💩

15. Libraries for Processing GNSS Data
▸ Gpsd
▸ Daemon for Unix-like systems
▸ Defines JSON-based request/response protocol
▸ Java Marine API - https://github.com/ktuukkan/marine-api
“If the GPSD project ever
needs a slogan, it will be
'Hide the ugliness!’”
Source: gpsd
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16. Connecting to External GPS Receivers
▸ Typically Bluetooth or USB
▸ nrjavaserial
▸ Under active development, fork of RXTX
▸ Bluecove (JSR-82, Java APIs for Bluetooth)
▸ Side note - Non-serial USB
▸ usb4java - JSR 80 compliant (OLD!)
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17. DEMO
GNSS NMEA
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Application
▸ Spring Boot
▸ nrjavaserial (USB), Bluecove (Bluetooth)
▸ Spring Integration
▸ Enterprise Integration Pattern (EIP)
▸ Micrometer
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NMEA Input Channel
Header Enricher
GS
Service Activator Service Activator
GSA
Service Activator
GGA
Service Activator
GS Aggregator
GS GGAGSA
NMEA Senten e ran or er
Senten e Channel
Header a ue o ter

19. Hillert Inc.
Micrometer + Prometheus + Grafana
▸ A fun way to create a UI (Dashboard)
▸ Micrometer - application metrics facade
▸ Hibernate for Metrics (Prometheus, Humio, Wavefront etc.)
▸ Simple to use in Spring Boot apps
▸ Prometheus - time series database / monitoring system
▸ Grafana - Monitoring + Dashboarding
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QGIS
▸ Geographic Information System
▸ “Painting” with GNSS Coordinates
▸ The OSS “IDE” for GIS People
▸ https://github.com/qgis/QGIS
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Field Surveys With Mergin and Input
▸ Create Forms and Data Collection Model in QGIS
▸ Run Input on your mobile device
▸ Automatic synchronization using Mergin
▸ Android and IoS support
▸ Alternative option QField
▸ Advice: Take pictures with Open Camera (OSS)
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22. DEMO
PLANTS
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Demo
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CSV
univocity
GeoJSON

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Thank YOU!
▸ Follow me @ghillert or connect via LinkedIn
▸ Additional information + Hardware Parts List
▸ https://www.hillert.com/
▸ Source Code
▸ https://github.com/ghillert/s1-2020-plants-demo
▸ https://github.com/ghillert/gnss-nmea-demo
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