Low-Cost High-Accuracy Receiver forEducation, Training and GIS Data Collection
Dinesh ManandharCenter for Spatial Information Science
The University of Tokyo
Contact Information: dinesh@iis.u-tokyo.ac.jp
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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High Accuracy Receivers are Expensive• High-Accuracy Survey Grade Receivers are multi-frequency andmulti-system receivers• L1/L2/L5, G1/G2, B1/B2/B3 etc• GPS, GLONASS, BGALILEO, BeiDou, QZSS etc• Price varies from $3, 000 to $30,000 or more.

• However, Low Cost Receivers are also capable of• Multi-System: GPS, GLONASS, GALILEO, BeiDou, QZSS, SBAS etc• Basically only in L1-Band Frequency• Low Cost: $300 (Multi-GNSS, L1 Only)• Very soon: Multi-System, Multi Frequency, L1/L2/L5• Broadcom, u-Blox and ST Micro already announced Multi-System, Multi-Band
GNSS Chips for Mass Market
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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How accurate is GPS Position?

50 cm grid

50 cm grid

5 cm grid

SPP (Single Point Position)

DGPS (Differential GPS)RTK (Real Time Kinematic)Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Errors in GPS Observation (L1C/A Signal)
Error Sources

One-Sigma Error , mSatellite Orbit
Satellite ClockTotal
2.1
2.1

DGPS
0.0
0.0

Ionosphere Error
Troposphere Error
Multipath

4.0
0.7
1.4

0.4
0.2
1.4

Receiver Circuits

0.50.5

Comments
Common errors are
removedCommon errors are
reducedIf we can remove common errors, position accuracy can be increased.
Common errors are: Satellite Orbit Errors, Clock Errors and Atmospheric Errors (within few km)
Table Source : http://www.edu-observatory.org/gps/gps_accuracy.html#Multipath

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Principle of Differential Correction
30

Send Correction Data to RoverFor Real-Time Position

RoverFor RTK, both rover and base receivers
need to use the same satellites
Antenna is installed at aUser in the Field
known-position(Either fixed or moving)Base-Station

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Principle of QZSS MADOCA and CLAS Services
QZSSGPSCorrection Data:
Satellite Orbit Error of GPS and Other Satellites
Satellite Clock Error of GPS and Other Satellites

Correction data for other satellites
will also be provided
RoverDinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Low-Cost High Accuracy System
GNSS Antenna
GNSS Antenna

Internet

Internet

Raspberry Pi 3B

NTRIPCasterWiFi

GNSS Receiver USB Cable
U-blox Neo-M8T

RasPi APP for RTK
SW Maps for GIS
Data Input

GNSSBase-StationBT

GNSS Rover Unit
(User in the Field)
Tablet
RasPi
APPVer. : 1.0

GNSSReceiver

NTRIP Caster

GNSS Base-Station

Low-Cost RTK System
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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RTK-Pi APP for Low-Cost RTK System

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Board Computer for Low-Cost RTK System
Raspberry Pi 3B forRaspberry Pi Zero w/WiFi & BT
Realtime and Postprocessing RTK
for Post-processing RTK

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Accuracy from Low-Cost RTK System
GNSS Antenna Rover
BTTabletRasPi
APPVer. : 1.0

Raspberry Pi 3B

WiFi
NTRIP
CasterRover-Station:
Receiver: u-blox M8T
Antenna: Zephyr 2Computer: RaspberryPi 3B+Distance between Base and Rover : about 12Km

5cm

GNSS Receiver
U-blox Neo-M8T

5cm

Base-Station:
Receiver: Trimble NetR9Antenna: Zephyr 2
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Data from Low-Cost RTK System

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Data from Low-Cost RTK System

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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RasPi Zero/W

Simple to Use, Plug-And-Record, Low-Cost System Receiver• Simple to Use, No Commands, Just One Time SettingAntenna• Connect Antenna, Receiver and Battery Pack

• Device Starts Logging GNSS Raw Data required for
RTK Post-Processing

GNSS Receiver

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Conclusion• Accuracy better than few tens of centimeters using Low-Cost
Receiver in RTK mode is possible.
• Both Base and Rover with Low-Cost Receiver• Smaller base length, < 10km• Accuracy better than few centimeters using Low-Cost
Receiver in RTK mode is possible.
• Base with High-End Receiver and Low-Cost Receiver• Smaller base length, < 5km• Our Target of Low-Cost High-Accuracy Receiver• $100x100cmx100gm (Cost- Accuracy-Weight)

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Additional Information

Please visit website at
http://www.csis.u-tokyo.ac.jp/~dinesh/https://www.youtube.com/watch?v=JaicV8egzFo
Contact:
dinesh@csis.u-tokyo.ac.jp
Sample Raw Data can be downloaded to Check Accuracy of RTK Processing
1. High-End Base (NetR9) Data vs Low-End Rover (u-blox M8T) Data
2. Low-End Base (u-blox M8T) Data vs Low-End Rover (u-Blox M8T) Data
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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