Low cost L1 GPS system suitable for PPK systems and precise navigation for Drones. Geomos and other structural monitoring systems. Safety systems where positioning is critical. Autonomous machine control, surface as well as Underground

1. Safety
Personal Safety
Precision
Navigation
Positioning
Asset monitoring
Research
Collision Avoidance
Cost Saving
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2. Base Line Extremes
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3. Gps Performance
Navigator Pro utilizes moving base technology enables the achievement of sub
meter accuracies.
The moving baseline (MB) mode differs from standard RTK operation in that the
base is no longer stationary at a pre-determined location. Both the base and rover
receivers are allowed to move while computing an accurate vector between the
receiver's antennae.
This mode enables the calculation of heading on dynamic or static platforms, plus
provides a centimetre level accurate 3D vector for use in dynamic positioning for
example, e.g. UAV ”Storing Event Markers on Rinex Files” feature.
Precise navigation and automation is becoming a topic that is discussed more
often than not
Using the moving baseline functionality with fixed base and rover antenna
positions on a platform gives the means to estimate the baseline angle with
respect to the local datum via the relative position information. This derived
angular error will then be proportional to the baseline length. Figure 3 (UBlox)
below provides the trend for baseline lengths up to 1 m for a typical (1 sigma)
relative position error of 0.8 cm. This is applicable to the use of a closed loop GPS
instead of an open loop GPS
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4. Gps Performance
Figure 3 courtesy of UBlox
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5. Navigator Pro Performance
Navigator Pro is a uniquely designed GPS that without any external correction
sources achieves sub meter accuracies.
With the addition of a fixed base and a communications network Navigator Pro
achieves sub decimetre accuracies.
Normally the following would be applicable when powering up a GPS
TTFF (Time to first fix) from a cold start is achieved in 26 seconds when observing
GPS and GLONASS.
Hot and aided starts fixes in approximately 2 to 3 seconds.
The unique design of Navigator Pro keeps the receivers alive resulting in a RTK fix
from a loss of lock in under a second from re-establishing a lock. A RTK fix from a
“cold start” in under a minute.
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6. Navigator Pro Performance
The example below indicates a single solution position with a baseline of 4.664 M
(the base line was 4.5 M) within a few seconds from startup
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7. Navigator Pro Performance
Navigator Pro achieves a Float solution a few sends later
with the base line 5.017 M as the GPS calculates the 3D
vector.
Once the vector has been calculated a Fix solution is
achieved and now has a base line of 4.511 M
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8. Navigator Pro Performance
Navigator Pro has the ability to resolve short base lines,
calculate Yaw (Dead Reckoning) and Pitch. With the
addition of another receiver Roll can also be calculated and
displayed. The display would be displayed in a graphical
format and can be used to guide machines in order to grade
access ramps accurately without having to exit the cab to
check grade boxes. Saving Surveyors time to construct the
grade boxes.
With the ability to give direction, accurate position and
height, Navigator Pro can direct a drill operator along a
previously calculated “flight Plan”, uploaded from the Rock
Engineer/Mine Planners office directly to the required drill
rig. The drill operator will be guided to the drilling position
in a similar fashion as a stake out function on a survey GPS.
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9. Navigator Pro Performance
Actual deployment of GPS Node with
restricted sky veiw
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10. Navigator Pro Performance
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11. Navigator Pro Performance
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12. Calculation of Pitch
Pitch: Base Line b = 820, Antenna height difference c
= 30mm Angle A = 2.095°
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13. Navigator Pro Performance
As can be seen from the previous 2 slides the GPS node
accurately calculates Pitch and Yaw and displays such
very accurately and is stable. Acquisition time from
start-up to resolving the short base line and pitch angle
is normally under a minute and once established
remains accurate even when moving, if lock is lost due
for instance passing under a structure such as a bridge
lock is re-established within about 7 seconds from
clearing the obstacle.
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14. Navigator Pro Performance
Base Performance u-center_v8.25u-Center.exe
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15. Navigator Pro Performance
Rover Performanceu-center_v8.25u-Center.exe
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16. Gps Performance
Base Rinex Data
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17. Gps Performance
Rover Rinex Data
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18. Gps Performance
Post Processed Datarudolfrover2.pos
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19. Navigator Pro
Safety
Navigator Pro provides accurate positioning in real time and all data is recorded
for future analysis such as incident reconstruction in conjunction with laser scans
etc.
An envelope is created around each node depending on the installation of such
node.
If the node is used for High wall monitoring no envelope is created.
If the node is installed in a vehicle or worn on a person, an envelope using
predetermined values to create a safety envelope around the machine/person
equipped with the node.
The node carried on a person or mounted to a vehicle allows for the “visibility” of
personnel or vehicles in the vicinity of moving earthmoving machines by
displaying their position and presence on the screen in the cab warning the
operator and the person/s or drivers about the danger/s present.
By adding low cost accelerometers (IMU’s ,3 axis Gyro) to predominately moving
nodes, additional real time data is provided in terms of acceleration ,
deceleration, vehicle tilt etc. A person carrying a node equipped with an
accelerometer will raise an alarm if the person falls off a machine.
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20. Navigator Pro
Safety
Predetermined values for minimum and maximum values for vehicle roll and pitch
can be programed into the node that will raise alarm when such hazards are
encountered
All impact alarms will be a “Red” alarm and all other alarms will be in 3 levels of
severity. “Yellow” entering a hazardous area , “Orange” in a hazardous area “Red”
should an impact alarm be detected. Impact alarms include collisions, sudden
acceleration or deceleration of moving nodes. Predominantly moving nodes can
also be Geofenced excluding access certain areas for unauthorised people, vehicle
etc.
Precision
Navigator Pro is an Autonomous GPS with sub meter accuracy without external
RTCM correction messages and sub decimetre accuracy with external RTCM
messages.
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21. Navigator Pro
Navigation
Navigator Pro provides precise navigation by means of a tablet that display maps of old
underground works and dangerous terrain with precise position indicated on the screen
allowing the operator to remain in predetermined safe areas
Positioning
Navigator Pro with external RTCM correction messages achieves decimetre accuracy in X, Y
and Z allowing for the precise positioning of mining machinery such as Drills. Hole depth
can also be verified using Navigator Pro.
Asset monitoring
Assets equipped with Navigator Pro can be Geo-fenced. If the asset then crosses the
predetermined Geo fence alarm is raised.
Research
Real time data, precision positioning and a variety of attachable sensor renders Navigator
Pro the ideal research tools for the industry.
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22. Navigator Pro Applications
 Monitoring. Navigator pro is a low cost accurate L1 GPS,
due to the low cost and factors such as low power
consumption and networkability makes it ideal for
monitoring of structures such as High walls and other
critical structures in conjunction with Radar and laser
scanners.
 Precise and real time monitoring of all moving equipment
inclusive of position, speed, payload and any other
functions deemed required for monitoring.
 Navigator Pro allows for the connection and real time
monitoring of numerous sensors such as air quality,
seismic, vibration and other sensors allowing real time
monitoring of for instance air quality inside and outside of
the machine cab.
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23. Navigator Pro Applications
 Real time data, Navigator Pro provides real time data
to whoever requires such, the production office will
know the position, speed and payload of all
production vehicles, bottle necks therefor can be
cleared by redirecting trucks.
 Grade slopes, Navigator Pro has the ability to display
various graphical aids such as angles etc. to the
operator.
 Data such as drill hole locations and grade slope data
can be uploaded to specific machines over the air
without the need to access the machine
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24. There are a plethora of applications of such a system . With the initial system built
from old RF receivers accuracies of 10 and 20 centimetres were achieved testing in
underground parking areas.
With the University of Johannesburg and Wits also getting involved in precise
underground research and having shared this with them I am sure that such a
system that is centimetre accurate will be available in the very near future making
mining that much safer and easier to mine.
The amount of real time data collected would therefor be invaluable for research
and with modern day electronics again any number of low cost sensors or where
required more precise sensors can be connected to the system and monitored.
I do not think such a system has ever been available to the mining of for that matter
any industry where precision in positioning is required.
Navigator Pro Applications
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25. With several nodes deployed on the surface of an underground mine to known positions
such as Main and Vent shafts and allowing the network of GPS node to synchronise as
close to zero Nano seconds as possible and taking the node position underground by means
of single mode fibre optic cable and connecting it to a RF network of nodes in an open loop
configuration will once the network is complete and the nodes have line of sight in a
zigzag patter along a tunnel propagate corrections to each other using the above ground
positions as reference and the RF nodes mounted to previously surveyed underground
points to correct themselves in relation to and synchronise with the above ground network
Any corrections to the known point with increased accuracy with be propagated via the
network to all other nodes allowing them to apply such corrections to themselves
eventually after applying all corrections and with a synchronised system any roving node
“seeing” 3 or more static nodes will after initialization be centimetre accurate.
From a safety and automation aspect this system can save lives by being able to send a
machine into a hazardous area instead of a person. This will in turn lead to the
development of autonomous and remote control (possibly from the surface) mining
machinery
Navigator Pro Applications
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26. Navigator Pro Operation
Navigator Pro is a unique designed low cost sub meter autonomous
GPS. It provides a continuous real time GPS and RTCM data
streams as well as Sensor data.
The data is transmitted by means of a low cost mesh network,
RTCM corrections are propagated by a stationery base as well as
between units allowing for sub decimetre accuracy.
Navigator Pro in a monitoring installation such as High Wall and
structural monitoring besides transmitting real time data samples
data is post processes at given time intervals to verify positions.
With the small packets of data and Mesh infrastructure the system
has a complete redundancy and fails safe back backbone whereas
the radios also synchronise and by means of RSSI (Received Signal
Strength Indicator) and TOF (Time Of Flight) calculates a vector
between itself and any other radios that it is connected to.
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27. Navigator Pro Operation
The vector is compared with the GPS receiver’s position and in time the
radio position will be the same as the GPS receiver’s position with the only
differences being the distances between the radio antenna and the Rover
antenna centre.
The system constantly does “health” checks on all nodes within the
network any node failures are reported via the network to the responsible
person for action to be taken. Replacement of a unit is as simple as
disconnecting the faulty node and connecting a new node and powering
it up. The node is intelligent enough to connect itself to the mesh, select
the strongest and most relevant nodes to itself initiate communications
with them, receive any updates since it was last powered up, do the maths
and precisely position itself.
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28. Navigator Pro Operation
Navigator Pro is besides modular and easy to deploy. The
units will upon power up establish it’s position and also
survey the mesh network and automatically select the
strongest signals.
Once radio communication is established the new node will
start receiving RTCM corrections and also broadcast its own
generated RTCM messages allowing the GPS Node correct
itself in relation to the base and the balance of the GPS
Nodes
Once the network has fully propagated the mean of
deviations are calculated for X,Y and Z. The correction values
for X, Y and Z are transmitted over the air to all GPS Nodes
that will apply the corrections to X,Y and Z for local Datum's
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29. Navigator Pro
The following slides from a random observation with
Navigator Pro node in full QD mode. All slides with
thanks to Tomoji Takasu
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30. 30
Acceleration Plot in QD Mode

31. 31
Dilution of Precision Plot in QD Mode

32. 32
Scatterplot in QD Mode

33. 33
Sky Plot in QD Mode

34. 34
Satellite Visibility Plot

35. 35
Position Plot in QD Mode

36. 36
Satellite Visibility Plot

37. 37
Sky Plot

38. 38
SNR / Multipath Plot in QD Mode

39. 39
SNR / Multipath / Elevation Plot

40. 40
Velocity Plot in QD Mode

41. Navigator Pro
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As can be seen from the previous slides Navigator Pro “Flat Lines” in QD Mode.
RTKLIB employs EKF (extended Kalman filter) in order to obtain the final solutions
in DGPS/DGNSS, Static, Kinematic and Moving‐baseline modes in conjunction with
the GNSS signal measurement models in the troposphere and ionosphere models.
But more importantly it also negates the effect of multipath on receivers without
specialised and expensive choke ring antennas under certain conditions. The
conditions are microprocessor and mathematically dependant and not receiver
dependant.
Open Loop systems allow for this the instance more than 2 nodes are able to establish
communication. Each and every node added strengthens the network and every other
Node. Besides applications for mining simple units can be designed for example a
small 5 / 10 or whatever number of portable units could be deployed anywhere where
research or where ever precise positioning is required. The radios are capable of
transceiving to a distance of 48 Km Line of sight (LOS) once all 5 units are connected
any roving node will accurate to at least a decimetre.