GPS in Mobile Application

GPS - Base Station - RTKs
Date: 14.09.2017
Presented by: Sonnet Xavier

OBJECTIVE
AT THE END OF THIS SESSION,
YOU WILL KNOW
2 Ⓒ 2017 QBurst Technologies | Confidential and Proprietary
1. GNSS
2. How does GPS work?
3. GPS errors and corrections
4. What is a base station?
5. What is an RTK?
6. GPS and construction equipments
7. Technical innovations in construction industry
8. AWARE

GNSS
GLOBAL NAVIGATION SATELLITE SYSTEM

GNSS
4
What is Satellite Navigation?
Ⓒ 2017 QBurst Technologies | Confidential and Proprietary
● Space Segment
● Control Segment
● User Segment
● GPS (NAVSTAR) - USA
● GLONASS - Russia
● Galileo - Europe
Components:
Examples:
A satellite navigation or satnav system is a system that uses satellites to provide
autonomous geo-spatial positioning.

GPS
GLOBAL POSITIONING SYSTEM

6
More satellites you find, More accurate your location
○ With 3 - Latitude & Longitude
○ With 4 - Altitude
GPS
THE MOST WIDELY USED GNSS IN
THE WORLD
How does GPS find you?
It is not the GPS which finds you, it's you who find the GPS

GPS
HOW DOES GPS WORK?
● Satellite transmits signals
○ Accurate timestamps
○ Orbit details (Satellite position)
○ L1 & L2 (Carrier Signals)
● GNSS Receiver
○ Antenna
○ Processing Unit
● Antennas receive the signals from satellites and
calculate the time difference.
● Distance = Time x Velocity

GPS
HOW DOES GPS WORK?

GPS
HOW DOES GPS WORK?
Receiver should collect signals from at least 3 satellites so
that it gets a precise position.
Processing unit then translates its own position into an earth
based coordinate system as
● Latitude
● Longitude
● Altitude
We could pinpoint our location with
● 5 - 10 meter Typical accuracy
● Around 15 meter potential Error due to:
○ Satellite Clocks
○ Orbit Errors
○ Ionospheric Delay
○ Tropospheric Delay

GPS
GPS APPLICATIONS
● Ground Mapping
● Transportation
● Machine Control
● Port Automation
● Precision Agriculture
● Timing
● Construction
● Marine
● Mining
● Surveying

GPS ERRORS AND
CORRECTIONS
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GPS ERROR
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GPS ERROR
IONOSPHERIC DELAY AND
TROPOSPHERIC DELAY
Multipath
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GPS ERROR CORRECTIONS
In general the techniques to resolve the Errors can be
described as:
● Averaging of repeated observations at the same location (the
least efficient method).
● Modeling of the phenomenon that is causing the error and
predicting the correction values.
● Differential Corrections (DGNSS).
○ RTK
○ Post-Processing
14

GPS AND
CONSTRUCTION FIELD
● Improves worker safety
● Reduces project delays
● Reduces fuel consumption
● Improves efficiencies at each stage of the project
● Also prevents theft or misplacement of construction equipment
● Provide real time monitoring for equipment maintenance
In construction fields we require a very high level of accuracy.
● Normal - 30’ accuracy
● We would require < 1’ accuracy
● How to bring the 30ft GPS window to much smaller???????
● Most widely used GPS Correction Methods: DGPS & RTK
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● Referred to as Differential GNSS / GPS
● GPS Error correction method
● In DGPS, two receivers are used, One receiver is located at accurately surveyed
point referred to as “Base Station”
● A correction is calculated by the known location of the base station to the
location determined by the GPS satellites
● The correction is then applied to the other receiver’s (referred to as “Rover”)
calculated position.
● This result is much more accurate, in fact this accuracy is normally 1.5 - 15 f.
● DGPS uses Pseudo Random Code (PRC) from satellite signals to calculate the
propagation delays and to calculate the underlying position. This is known as
Code- based Positioning
DGPS OR DGNSS
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DGPS
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BASE STATION
AND ROVER
Base Station
● A base station is a GPS receiver at an accurately-known fixed location which is
used to derive correction information for nearby portable GPS receivers.
● “Known position” - It has a high degree of accuracy using a surveyed location or
by averaging its position over time (12-18 hours usually)
Rover
● The rover is a GPS receiver is mounted on a pole, vehicle, marine vessel, or in a
backpack, and is moved between the points that require measurement or
Location.
18

BASE STATION
AND ROVER
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RTK - REAL TIME
KINEMATICS
● GPS Error Correction method
● RTK uses a similar set-up to the DGPS system (Base Station and Rovers)
● Unlike DGPS, RTK uses carrier-based ranging for its underlying position
information
● The base station for the RTK setup transmits the phase of the signal that it
observes and sends that information to the rovers who then compare that to the
phase that they observe
● RTK gives very high level of accuracy, upto 1cm - 1ppm
20

RTK
21

Fixed RTK
AMBIGUITY RESOLUTION
RTK uses a complicated mathematical formula or algorithm to calculate the exact
number of radio wavelengths between the satellites and the base station antenna and
yield either a Fixed or Float solution.
● If a sufficient number of satellites are visible, RTK can provide a fixed
position, within a fraction of an inch (0.01 - 0.1 f)
● In a fixed solution, the number of wavelengths is a whole number, or
integer, and the algorithm is constrained to yield a whole number
22

AMBIGUITY RESOLUTION
Float RTK
In a float solution, the algorithm does not yield an acceptable fixed solution, so the
ambiguity is allowed to be a decimal or floating point number
● A low number of visible satellites
● Poor satellite constellation geometry
● A poor radio link between the base station and the rover may
prevent a fixed solution (< 1 f).
23

GPS CORRECTION
1. Autonomous
30 - 45 ft
2. DGPS
1.5 - 15 ft
3. Float RTK
< 1 ft
4. Fixed RTk
0.01 - 0.1 ft
24

GPS AND CONSTRUCTION
EQUIPMENT
Man rovers in the field conduct topos on the site, measure stockpiles, layout the project
and stake out pads, roads and other project elements
25

EQUIPMENT
On excavators, the GPS/GNSS antenna is usually mounted on near the counterweight
26

EQUIPMENT
The antenna for machine rovers are typically moved on the blade and use the
corrected GPS signals to guide the dozers or motor graders to the exact coordinates
of the finished surface
27

SOLUTION PROVIDERS
Trimble & Sitech (the distribution channel for Trimble products)
● SCS900 Site Controller Software
● SPS855 GNSS Modular Receiver
● SPS985 GNSS Smart Antenna
28

TRIMBLE - SPS985 GNSS
SMART ANTENNA
Features and Benefits:
● Rugged, All-in-one Solution
● Trimble xFill Technology
● Flexibility
Applications:
● Wi-Fi Base Station
● Rover
29

CATERPILLAR
DETECT FOR PERSONNEL
Provide a technology to detect ground
workers in an unsafe area behind the
equipment.
30

TRIMBLE - SPS985 GNSS
SMART ANTENNA
Redpoint
● Indoor GPS for Construction Safety
○ Using RTLS (Real Time Location System)
○ https://www.youtube.com/watch?v=Vi0WEQQmzPY
Nextpoint
● NextPoint provides Construction Equipment GPS Tracking Systems for any type
of small, medium or large commercial equipment or mobile asset.
● System can track every movement and event in real time.
31

AWARE
WORK ZONE INTRUSIONS
32

AWARE
Oldcastle Materials Group along with QBurst & Artis are developing a system of
sensors to help detect and prevent accidents caused by intrusions into mobile
work zones nationwide.
The system is called AWARE and involves a suite of devices designed to
monitor traffic flow in and around mobile work zones.
It was designed specifically to detect traffic incursions at the job site using GPS
and provide advanced warning to all personnel, helping to prevent injury.
The AWARE System has four main components:● A high tech sensor called the Raven
● A GPS-based worker alert unit called WorkTrax
● A visible and audible alert system for the traveling public
(threat deterrent)
● An AWARE application that runs on an iPad or tablet. The
devices and the application communicate with each other
over a Digi network using BLE technology.
33

AWARE
THIS IS OUR “WHY”
The STATS:
● According to the National Highway Traffic Safety Administration
(NHTSA), 80% of accidents and 60% of highway deaths are the result of
distracted drivers.
● Vehicle Intrusions are the leading cause of worker fatalities with the
road construction industry. In 2013, there were 67,523 crashes in work
zones. In 2014, there were 669 fatalities from crashes in work zones
35

WHAT IS AWARE
A system of sensors designed to detect
work zone intrusions that includes
radars, GPS sensors, motion sensors,
optical sensors, and carefully tailored
software.
SYSTEM COMPONENTS
36
RAVEN WORKTRAX THREAT DETERRENT BASE STATION

Workers with WorkTrax
AWARE
Watch video
34

AWARE
HOW DOES IT DETERMINE THE
WORK ZONE BOUNDARIES?
● The GPS records where your machine has been
● The radar tracks where normal traffic is flowing
● Using both GPS and radar, we determine the boundary between traffic flow and
active work (shown in red)
37

AWARE
HOW DOES IT WORK?
● We track all vehicles as they approach within 600’ of the Raven
● The radar measures speed, position and trajectory.
● The system alerts drivers and workers in unsafe circumstances exist.
● 3 Basic applications
38

AWARE
3 BASIC APPLICATIONS
Stationary Situation –
Flagging Station,
Maintenance Crews, Lone
Worker
Moving Merge – MOT (cone)
Trucks, Striping Operations,
Sweeping Operations, Road
Rangers, School Buses
Active Work Zones – Paving,
Milling, or Construction
Operations within (non-protected)
lane closure
39

OLDCASTLE
MATERIALS GROUP
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OLDCASTLE
AN INDUSTRY LEADER
COMMITTED TO SAFETY
AND CUSTOMER SERVICE
Oldcastle Materials is the leading vertically integrated supplier of aggregates,
asphalt, ready-mix concrete, and construction and paving services in the United
States.
No. 1 Asphalt producer in North America
No. 1 Asphalt paver in North America
No. 2 Aggregates producer in North America
No. 2 Cement producer in Canada
No. 2 Ready-mix producer in North America
41

OLDCASTLE
MATERIALS GROUP
1,500+ Locations
20,000+ Employees
Product Position
Asphalt
RMC
Aggregates
No. 1
No. 3
No.3
42

HOW YOU KNOW US……
43

PART OF A BIGGER
COMPANY
+90,000
People
31
Countries
44

QUESTIONS ?
45

THANK YOU
45

GPS in Mobile Application

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