Introduction to QZSS,GNSS Positioning Methods and
Low-Cost Receiver Systems
Faculty Development Program (FDP) on GNSS/ NavIC and Applications
21 – 25 September 2021
Dinesh Manandhar, Associate Professor (Project)

Center for Spatial Information Science (CSIS), The University of Tokyo
22nd September 2021
dinesh@csis.u-tokyo.ac.jp2021/09/22 9:16 PM

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

Slide : 1

QZSS (Quasi-Zenith Satellite System)“MICHIBIKI” Introduction

Image: MGA 2019, Mitsubishi

2021/09/22 9:16 PM

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

Slide : 2

QZSS Introduction• The first QZSS satellite was launched in September 2010.
• Today, there are four satellites in the space.
• QZSS orbit is designed so that it can provide good position data even inhighly dense urban area like Tokyo.
• It is designed interoperable with GPS satellites.
• QZSS provides unique new services such as MADOCA, CLAS and DCR.
• QZSS was declared operational in November 2018.
• The future constellation of QZSS will have 7 satellites.
• QZSS Information Links:• https://qzss.go.jp/en/overview/downloads/movie_qzss.html• https://qzss.go.jp/en/
2021/09/22 9:16 PM

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

Slide : 3

QZSS was Declared Operational on 1st NOV 2018

Declaration Ceremony of QZSS Operation

http://qzss.go.jp/events/ceremony_181105.html

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

Slide : 4

QZSS Signals and PRN ID
PRN
193
183
193
194
184
196
194
199

SVN

Satellite

Launch Date
(UTC)

Orbit

J001

QZS-1

2010/9/11

QZO

J002

QZS-2

2017/6/1

QZO

L1C/A, L1C, L2C, L5
L1S
L6
L1C/A, L1C, L2C, L5
L1S
L5S
L6
L1C/A, L1C, L2C, L5

189
197
137
199
195
185
200
195

Positioning Signals

J003

QZS-3

2017/8/19

GEO

J004

QZS-4

2017/10/9

QZO

L1S
L5S
L1Sb
L6
Sr/Sf
L1C/A, L1C, L2C, L5
L1S
L5S
L6

Source: https://qzss.go.jp/technical/satellites/index.html
2021/09/22 9:16 PM

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

Slide : 5

QZSS Constellation Plan

Equator1 sat constellation

4 sat. constellation

7 sat. constellation

Number of Satellites

QZO ●: 1

QZO ●: 3, GEO ●: 1

QZO●:4, GEO●:2, QGO●:1

PurposeResearch & Development

Operational

Operational,

Government Authority

JAXA

Cabinet OfficeCabinet Office

Operation

2010～（10 years）

2018～（15 years）

2023～（15 years）

Service Time / day (Japan)

8 hours / day

24 hours / day

24 hours / dayComplements GPS for
positioning

QZO: Quasi-zenith Orbit / GEO: Geosynchronous Orbit / QGO: Quasi-geostationary Orbit
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@csis.u-tokyo.ac.jp

Autonomous Positioning
Capability with QZSS only

Source: MGA 2019, Mitsubishi
Slide : 6

This slide is taken from presentation slides of S. Kogure, Introduction to Michibiki and EWS, presented on 13th July 2021
2021/09/22 9:16 PM

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

Slide : 7

Characteristics of QZSS
•
•
•
•
•

QZSS signal is designed in such a way that it is interoperable with GPS
QZSS is visible near zenith; improves visibility & DOP in dense urban area
Provides Orbit Data of other GNSS signals
Provides Augmentation Data for Sub-meter and Centimeter level position accuracy
Provides Messaging System during Disasters

http://qzss.go.jp/en/overview/services/sv04_pnt.html

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

Slide : 8

Merits of QZSS• Disaster and Crisis
Management• Short Message broadcast
during Disaster

http://qzss.go.jp/en/overview/services/sv04_pnt.html• Sub-Meter Level Augmentation
Service (SLAS)

Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@csis.u-tokyo.ac.jp• High-Accuracy Positioning
Services• CLAS and MADOCA

Slide : 9

This slide is taken from presentation slides of S. Kogure, Introduction to Michibiki and EWS, presented on 13th July 2021
2021/09/22 9:16 PM

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

Slide : 10

This slide is taken from presentation slides of S. Kogure, Introduction to Michibiki and EWS, presented on 13th July 2021
2021/09/22 9:16 PM

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

Slide : 11

How does a GPS/GNSS Receiver Work?

2021/09/22 9:16 PM

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

Slide : 12

GNSS: How does it work?
Determine the Distance using Radio Wave
0ms

Assume that the Satellite Transmits Signal at 0ms.

If Receiver receives the same Signal after 67ms,
Distance = 67x300,000 = 20,100Km

25ms
50ms

0ms
Satellite with a known positiontransmits a regular time signal.

75ms

25ms
50ms

Distance = (Reception Time - Transmission time) × Speed of light
Speed of Light: 300,000 km/s
2021/09/22 9:16 PM

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

Slide : 13

GNSS: How does it work?
Principle of Satellite-based Navigation(xk, yk, zk)

Receiver generates its own GPS signal similar to the signal
coming from the satellite for each satellite
Its called Replica Signal
The Replica Signal includes PRN Code and Carrier Signal
This Replica Signal is moved forward and backward to
match with the incoming signal

𝜌𝑘 =𝑥0 − 𝑥𝑠𝑘2+ 𝑦0 − 𝑦𝑠𝑘2+ 𝑧0 − 𝑧𝑠𝑘2+𝜀(x0,y0,z0)

If k ≥ 4, solve for x, y, z and errors including clock bias 𝜀2021/09/22 9:16 PM∆t

Correlation between Incoming Signal andReceiver Generated Signal

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

Slide : 14

Error sources
Satellite Orbit Error
V = 4km/s

Satellite Clock Error

Ionospheric Delay
50 – 200Km

Tropospheric Delay
10Km
Multipath

Thermal Noise
Receiver Clock Error
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@csis.u-tokyo.ac.jp

Slide : 15

Pseudorange equation
Ideal Case:

𝜌0 = 𝑐 𝑡𝑟 − 𝑡𝑠

Real Case:𝜌 = 𝜌0 + 𝑐 𝛿𝑡𝑟 − 𝛿𝑡𝑠 + 𝐼𝑜𝑛𝑜 + 𝑇𝑟𝑜𝑝𝑜 + 𝑀𝑢𝑙𝑡𝑖𝑝𝑎𝑡ℎ + 𝜉
Thermal Noise
Multipath Error

Receiver Clock Error

Tropospheric Delay

Satellite Clock Error

Ionospheric Delay

Simplified Equation:𝜌 = 𝜌0 + 𝑐 𝛿𝑡𝑟 − 𝛿𝑡𝑠 + 𝜀

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

Slide : 16

Pseudorange model𝜌=𝑥 − 𝑥𝑠2+𝑦 − 𝑦𝑠2+𝑧 − 𝑧𝑠 2 + 𝑐 𝛿𝑡𝑟 − 𝛿𝑡𝑠

Satellite+𝜀𝑥𝑠 , 𝑦𝑠 , 𝑧𝑠

𝜌0𝜌0Where:
x, y, z : Unknown receiver positiondelta tr: Unknown receiver clock error
epsilon : minimize this error by finding an optimal solution𝑥, 𝑦, 𝑧Receiver In order to solve the above equations, we need “n” simultaneous
nonlinear equations from “n” pseudorange observations.
 We need at least 4 independent observations in order todetermine 4 unknown parameters, x, y, z and receiver clock error.

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

Range between satellite and receiver

Slide : 17

GPS L1C/A Signal Structure (Satellite Side)
900 Phase Reversex154

L1 Carrier, 1575.42Mhz
Carrier Signal∑
X1, Clock10.23Mhz

x1/10

PRN Code, 1.023Mhz
PRN Code

Atomic ClockRb or Cs Clocks

L1 Band GPS Signal

x1/204600

Navigation Data, 50Hz
Navigation Data

2021/09/22 9:16 PM

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

Slide : 18

GPS L1C/A Signal Structure• Carrier Signal• It defines the frequency of the signal• For example:• GPS L1 is 1575.42MHz, L2 is 1227.60MHz and L5 is 1176.45MHz• PRN Code• Necessary to modulate carrier signal• Used to identify satellite ID in the signal• Should have good auto-correlation and cross-correlation properties• Navigation Data

• Includes satellite orbit related data (ephemeris and almanac data)• Includes satellite clock related information (clock errors etc.)• Includes satellite health information

2021/09/22 9:16 PM

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

Slide : 19

Block Diagram of GPS Receiver
GPS Antenna
AGC

Pre-Amp
LNA

Oscillator(Clock)Down Converter

A/D Converter

Frequency
Generator

Replica Signal
Generator

Acquisition

Tracking

Navigation Data

Position Output

2021/09/22 9:16 PM

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

Slide : 20

GPS L1C/A Replica Signal at Receiver Side
x154

L1 Carrier, 1575.42Mhz
Carrier Signal∑
ReceiverClock10.23Mhz

x1/10

PRN Code, 1.023Mhz
PRN Code

L1 Band Replica GPS Signal

Unknown Data
x1/204600
The receiver demodulates the signal toretrieve Navigation
Data
Navigation Data,
50Hz
Navigation Data

2021/09/22 9:16 PM

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

Slide : 21

How does GPS Signal Look Like?
5

File: JAX_LIV.dat
Frequency-domain
Plot of15 GPS IF Signal (Fourier Transform)

4

10

3

5

Magnitude, dB

Amplitude

2
1
0
-1

0
-5
-10

-3

-20

-4

-25

-5

0

0.005

0.01

0.015

0.02
Time (ms)

0.025

0.03

0.035

Tracking Output (I and Q Channels)

16000
14000

-15

-2

HistogramFile:ofJAX_LIV.dat
GPS IF Signal

Number of Samples in a Bin

6

Histogram of IF Data

Frequency Domain Plot of IF Data

Time Domain Plot of IF Data

JAX_LIV.dat
Time-domainFile:Plotof GPS IF Signal

12000
10000
8000
6000
4000
2000

0

2

Acquisition of GPS L1C/A Signal with Low Noise468Frequency (MHz)

10

12

0
-5

-4

-3

-2

-1

0
1
Bin Value

2

3

4

5

Acquisition of GPS L1C/A Signal with Higher Noise

Scatter Plot of I and Q Channels, shows BPSK Modulation

2021/09/22 9:16 PM

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

Slide : 22

PRN (Pseudo Random Noise) Code• PRN Code is a sequence of randomly distributed zeros and ones that is one millisecond long.
• This random distribution follows a specific code generation pattern called Gold Code.
• There are 1023 zeros and ones in one millisecond.

• Each GPS satellite transmits a unique PRN Code.
• GPS receiver identifies satellites by its unique PRN code or ID.

• It continually repeats every millisecond• The receiver can detect where the PRN code terminated or repeated.
• A unique sequence of bits indicates start of a PRN code.

• It helps to measure signal transit time and compute pseudorange between the receiver and the satellite• Its also called C/A (Coarse Acquisition) code in GPS

1ms / 1023

Unique Sequence at thestart of the PRN code0 1 0 1 0 0 11 0 1 0 0
1ms

2021/09/22 9:16 PM

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

Slide : 23

Pseudorange (Code-Phase Measurement) - 1
Transmission
Time

Pseudorange = (Reception Time – Transmission time) x Speed of Light

Signal propagation at the speed of light

About 20,000 km

Reception
Time

Transit time

A GPS receiver measures the signal transmission timefrom the code phase at signal reception time.
2021/09/22 9:16 PM

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

Slide : 24

Pseudorange (Code-Phase Measurement) - 2
1-sequence of PRN Code is 1023 bits, 1ms long.
This corresponds to 300Km
1-bit or chip corresponds to 1/1023 ms.
This is about 293m (say 300m) in distance.
In the receiver, signals are resampled at certain frequency, say 10MHz.
This means every chip will be further divided into 10 smaller chips.
If it is possible to detect code phase at 1/10 of this sampled chip, then range
measurement accuracy would be about 300/10/10 = 3m.
However, there are various types of noises and this accuracy may not be possible.
Normally, GPS L1C/A guarantees an accuracy within 10m.
Thus, using Code-Phase (PRN code) measurement, the accuracy will be limited to few
meters level.

2021/09/22 9:16 PM

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

2mSlide : 25

Carrier-Phase Measurement – 1• Carrier-Phase measurement is done by counting the number of cycles coming from the satellite to thereceiver.
• However, there are many complexities in measuring total number of cycles (N) from the satellite to thereceiver.
• This is called integer ambiguity• This is due to the fact that all cycles are the same and there are no headers to tell the receiver when a new cycle has
arrived after number of cycles as in PRN code.
••

A PRN code has a header to tell the receiver that this is the beginning of the PRN code that is 1023 chips long.
There are algorithms to solve this problem of ambiguity resolution.

• One complete cycle for GPS L1 band is 19cm long.
• Thus, if we can measure one wavelength, we can get 19cm accuracy• If we can measure 1/10th of a cycle, we get about 2cm accuracy.
• Thus, Carrier-Phase measurement can provide centimeter level accuracy.

2cm

19cm

2021/09/22 9:16 PM

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

Slide : 26

21,000

600

300

000

Code-Phase (PRN Code) vs. Carrier-Phase Measurement

19cm

Code-Phase Measurement
Measuring distance between the satellite and the receiver with a tapethat has distance markings as well as distance values written. So that we
can measure correct distance.

Carrier-Phase Measurement
Measuring distance between the satellite and the receiver with a tapethat has distance markings but distance values are not written. We only
know that each distance marker is 19cm apart. So, we need to count at
certain point the number of cycles separately that’s coming to thereceiver. This is called integer ambiguity solving.

Only provide meter level accuracy

Provides centimeter level accuracy

Simple and required measurement. It’s part of signal demodulation
process. So this can’t be avoided.

Counting of number of cycles (solving integer ambiguity) is not required
if carrier-phase based measurement such as RTK or PPP is not required.

2021/09/22 9:16 PM

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

Slide : 27

How to Improve GPS Accuracy?

2021/09/22 9:16 PM

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

Slide : 28

GPS Position Accuracy
How to achieve accuracy from few meters to few centimeters?
metercentimeter

50 cm grid

50 cm grid

5 cm grid

SPP (Single Point Position)

DGPS (Differential GPS)
Code-phase observation

RTK (Real Time Kinematic)
Carrier-phase observation

2021/09/22 9:16 PM

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

Slide : 29

Errors in GPS Observation (L1C/A Signal)
Error Sources
Satellite Orbit
Satellite Clock
Ionosphere Error
Troposphere Error
Multipath
Receiver Circuits

One-Sigma Error , m
Total
DGPS
2.0
0.0
2.0
0.0
4.0
0.4
0.7
0.2
1.4
1.4
0.5
0.5

Comments
Common errors are removed

Common errors are reduced

If we can remove common errors, position accuracy can be increased.
Common errors are: Satellite Orbit Errors, Satellite Clock Errors and Atmospheric Errors (within few km)
Values in the Table are just for illustrative purpose, not the exact measured values.
Table Source : http://www.edu-observatory.org/gps/gps_accuracy.html#Multipath
2021/09/22 9:16 PM

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

Slide : 30

How to Improve Accuracy?
• Both Code-Phase and Carrier-Phase observations are necessary• Carrier-phase provides centimeter level resolution• Need to remove or minimize the following errors:• Satellite Related Error• Satellite orbit errors• Satellite clock errors• Space Related Errors• Ionospheric errors• Tropospheric erros• Receiver Related Errors• Receiver clock error• Receiver circuit related
2021/09/22 9:16 PM

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

Slide : 31

High-Accuracy Observation Methods• Basically three types of Observation• DGPS (Differential GPS)• Code-phase observation• Requires Base-station (Reference Station)• RTK (Real Time Kinematic)• Code-phase and Carrier-Phase Observation• Requires Base-station (Reference Station)• PPP (Precise Point Positioning)• Code-phase and Carrier-phase observation• Does not require base-station

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

Slide : 32

Which Method: DGPS, SBAS, RTK, PPP?

http://www.novatel.com/an-introduction-to-gnss/chapter-5-resolving-errors/
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@csis.u-tokyo.ac.jp

33

Slide : 33

How to Remove or Minimize Common Errors?
Use Differential Correction
30

Recommended Base-length < 40Km
Send Observation Data to Roverfor Real-Time Position
Base-Station

Rover
For RTK, both base and rover receivers need toAntenna is installed at aUser in the Field
use data from the same satellites
known-position(Either fixed or moving)Base-station Antenna position
Use RINEX data for post-processing
shall be known in advance
2021/09/22 9:16 PM

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

Slide : 34

How to Remove or Minimize Common Errors?
Principle of QZSS MADOCA and CLAS Services
QZSS

GPS

Currently, MADOCA provides correction
data for GPS, GLONASS and QZSS.
It will be extended for Galileo in future.

Correction Data:
Satellite Orbit Error of GPS and Other Satellites
Satellite Clock Error of GPS and Other Satellites

Base-Station is not required.
The Rover receiver should be able to receiver MADOCA
signal in L6 band.
MADOCA correction data is also available online.

Rover
2021/09/22 9:16 PM

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

Slide : 35

Low-Cost High-Accuracy Receiver Systems
RTKDROID, MADROID, MAD-WIN, MAD-π

2021/09/22 9:16 PM

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

Slide : 36

Objectives• Develop Low-Cost High-Accuracy Positioning Systems (L-CHAPS)• System Integration of commercially available receiver or module•

For RTK and MADOCA• Avoid use of computer to minimize the cost•

Use Single Board Computer (SBC)•

Use Tablet or Smart-Phone••

RaspberryPi, Arduino, Spresense

Android devices are quite flexible and easier to use$100 System PPKPC• Develop Easy to Use System in Field••••

A user without GNSS knowledge shall be able to use
Self-understanding interface
Suitable for remote operation and data logging
Operate with mobile power-banks• Promote GNSS and MADOCA Technologies Abroad through• Lectures, Trainings, Seminars, Workshops and Events• Joint Research and Joint Projects

2021/09/22 9:16 PM

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

Slide : 37

GNSS Equipment for Education and Training
Low-Cost GNSS Receivers are necessary for promotion of GNSS technology to conduct lectures, trainings and pilot projects.
We need low-cost high-accuracy receivers in large quantities.

2021/09/22 9:16 PM

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

Slide : 38

Low-Cost High-Accuracy Receiver system Development Cycle
DEC, 2016

MAY, 2017

Low-Cost RTK

MAR, 2018

Low-Cost MADOCA

Android Device
RTK / MADOCA / EWS / SAR
System2022

Enhancement of
MADOCA System
2021

What type of smart-phone
will emerge by 2025 ?

DEC, 20192021/09/22 9:16 PM

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

Slide : 39

Our Definition of Low-Cost High-Accuracy

Type
RTK

Target
Cost$100

Current Cost

Description$300 - $600

Single or Dual Frequency Receiver
Dual Frequency Antenna
RaspberryPi Device$500 - $1,000

Dual Frequency GNSS Receiver
Triple Frequency GNSS Antenna
RaspberryPi Device

Cost
MADOCA•$300

Difficulties

Low-cost MADOCA module is not
yet available off-the-shelf
Cost factor of Antenna

Cost of accessories, cables, connectors and power supply unit are not included

2021/09/22 9:16 PM

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

Slide : 40

Many Applications require
Low-Cost, Small-Size & Low-Power
Receiver System
But, is it possible to get
High-Accuracy with Low-Cost Receivers?

Although the Normal Accuracy of GPS is about 10m,
why can we get Centimeter Level Accuracy?

2021/09/22 9:16 PM

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

Slide : 41

High-End Survey Grade Receivers
L5/E5/B2/L3

L2

L6/E6/B3

L1/E1/B1• Multi-frequency• GPS• GLONASS• GALILEO• BDS• QZSS• NAVIC: L1/L2/L5: L1/L2/L3: E1/E5/E6: B1/B2/B3: L1/L2/L5/L6: L5/S• Multi-system• GPS, GLONASS, GALILEO, BeiDou, QZSS,NAVIC, SBAS etc• Price varies from $1, 000 to $30,000 or
more
2021/09/22 9:16 PM

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

Slide : 42

Low-Cost Receivers
L1/E1/B1*• Multi-System• GPS, GLONASS, GALILEO, BeiDou, QZSS, SBAS etc• Basically Single Frequency• L1/E1/B1-Band• Very soon: Multi-System, Multi Frequency, L1/L2 or L1/L5• Future trend for Mass Market System will be L1/L5• Some chip makers have already announced Multi-System, MultiFrequency GNSS Chips for Mass Market• Low Cost:• Less than $300 (Multi-GNSS, L1 Only) including Antenna and allnecessary Hardware, Software• Our target is within $100 including everything.

*Note: Only one signal type from each system is processed
e.g. GPS has L1C/A and L1C in L1, ,but only L1C/A is used in Low-Cost Receiver
2021/09/22 9:16 PM

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

Slide : 43

Low-Cost RTK Receiver System
TYPE R1 Type A: Low-Cost, High-Accuracy Receiver System

TYPE R2 Type B: Low-Cost, High-Accuracy Receiver System

Real-Time and Post-Processing, Base and Rover Mode
GNSS Antenna RoverBT

GNSS
ReceiverFor Post-Processing & Rover Mode Only

TabletRasPi
APP
Ver. : 1.0

GNSS Antenna Rover
Raspberry Pi Zero w/WiFi&BT

Raspberry Pi 3B

GNSS
Receiverinternet

RTCM for
RTK

TYPE A1NTRIP
CasterType C: Low-Cost, High-Accuracy Receiver System
Real-Time and Post-Processing, Rover Mode Only

TYPE MA

GNSS Antenna Rover

Type D: Low-Cost, High-Accuracy Receiver System
Real-Time and Post-Processing, Rover Mode Only

GNSS Antenna Rover

GNSS
ReceiverAndroid
DeviceRTKDROID
Ver. : 1.0

RTCM for
RTK

GNSS
ReceiverInternet

Internet
NTRIP
Caster2021/09/22 9:16 PM

Android
Device
MADROID
Ver. : 1.0

RTCM and/or SSR
PPP-RTK
e.g. MADOCA Service

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

MADOCA
Correction
ServerSlide : 44

Type – A1: GNSS Receiver with Android Device

GNSS Antenna Rover

GNSS
ReceiverAndroid
DeviceRTKDROID
Ver. : 1.0

RTCM forReal-time
RTK
WiFi

Type A1:
Rover Mode
Real-Time and Post-Processing RTK
Based on RTKLIB Engine
Real-time processing in Android Device
APP: RTKDroid
2021/09/22 9:16 PM

NTRIPCasterDinesh Manandhar, CSIS, The University of Tokyo, dinesh@csis.u-tokyo.ac.jp

GNSS Receiver Module

Slide : 45

Screen Shots of RTKDROID and MADROID
Connect GNSS receiver toAndroid device(1) RTKDROID :For RTK or PPK(2) MADROID:
for MADOCA-PPP,
MADOCA-PPP/AR (future)

2021/09/22 9:16 PM

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

Slide : 46

MADOCA System: Direct from QZSS or Online Correction Data
GNSS Receiver Only

QZSS

QZSS

GNSS Signals

GNSS Signals

GNSS Receiver + MADOCA Decoder

Antenna

Antenna

GNSS /
MADOCA
Receiver

MADOCA PPP
Processor

Position
OutputGNSS
Receiver

MADOCA PPP
Processor

Position
OutputOnline MADOCA
Correction Data

2021/09/22 9:16 PM

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

Slide : 47

How does MADOCA Work?
• MADOCA• Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis• Provides an accuracy of 10cm
• MADOCA signal broadcasts the following correction data:• Satellite Orbit, Satellite Clock, Signal Biases• Currently, correction data are broadcasted for GPS, GLOANSS
and QZSS satellites
Interval

RTCM Message

product
Estimate

ProvideGPS

GLONASS

QZSS

Orbit correction

30

1

1057

1063

1246

Clock correction

1

1

1058

1064

1247

HR-Clock correction

1

1

1062

1068

1251

URA

1

1

1061

1067

1250

Image from presentation file: Introduction to MADOCA by H. Kakimoto, GPAS Company

Table Source: https://www.gpas.co.jp/service_madoca.php
2021/09/22 9:16 PM

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

Slide : 48

Low-Cost MADOCA Receiver Systems: Product Types
MAD-WIN

MAD-π

MADROID

Platform / OS

Windows

RaspberryPi 3B or 4B

Android Device

GNSS ReceiverDefault : u-blox F9P
Other: Any dual-frequency ReceiverDefault : u-blox F9P only

Default : u-blox F9P
Other: Any dual-frequency Receiver

MADOCA Receiver

U-blox D9 only

U-blox D9 only

NA (MADOCA Online Correction Data only)

GNSS Receiver Data
FormatUBX, SBF, RTCM3UBX
SBF, RTCM3 (For online GNSS data)

UBX

MADOCA Correction Data
Format (Satellite)

UBX only

UBX only

NA

MADOCA Correction Data
Format (Online)

Online Services
from GPAS, UTokyo (Test Level)
UBX or RTCM3

Online Services
from GPAS, UTokyo (Test Level)
Online Services
UBX or RTCM3

GPAS Services,
RTCM3
UTokyo Online Service in the next release

System Architecture

2021/09/22 9:16 PM

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

Slide : 49

MADOCA PPP Receiver System

Use this baud-rate to receiver
GNSS Raw Data

Use this baud-rate to receiver
MADOCA Data

65

Antenna
F9P GNSS Receiver
L1/L2/E5B

50

MADOCA Decoder
QZSS L6

COM Port: 1
GNSS DataCOM Port: 2
MADOCA Data

GNSS Antenna

2021/09/22 9:16 PM

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

Slide : 50

MAD-WIN / MAD-PI User Interface

Log Files:
1. Solution: MADOCA PPP Solution in NEMA format
2. Rover: Rover RAW Data in receiver’s proprietary format
Can be used for PPK (Post-Processing Kinematic) Solution or
Post-Processing PPP
3. Correction: MADOCA PPP Correction Data in receiver’s
proprietary format
Can be used for Post-Processing MADOCA
2021/09/22 9:16 PM

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

Slide : 51

MAD-WIN Data Observation
Receiver: Online receiver access in Kashiwa / Correction Data: MADOCA Receiver in Bali
After three hours observation

After two hours observation

After few minutes observation

2021/09/22 9:16 PM

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

Slide : 52

MAD-PI:MADOCA with RaspberryPi Device• MAD-Pi has been tested with RaspberryPi-3B device• It also works with RaspberryPi-4B• If the device does not work, please try with a different USB port

• Do not remove and insert SD Card several times. It may getdamaged.
• Observation data can be logged to an external USB memory
disk. Memory drive of upto 64GB is supported.
• Files are created at 6-hour interval with Date/Time based filename.

• Ras-Pi 4 device consumes more power than Ras-Pi 3 device.
Continuous operation of the device will generate heat. Keep
the device in well ventilated area
• Do not keep the device in a closed box• We have set both Ras-Pi 3 and Ras-Pi 4 devices with touch
screens for easy operation.
• Mouse and External keyboard can be connected either via BT or USB ports• Ras-Pi device can be connected by an Android device using BT

Raspberry-Pi device with Touch Screen
2021/09/22 9:16 PM

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

Slide : 53

MADOCA Data Processing

2021/09/22 9:16 PM

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

Slide : 54

GNSS Data Processing Software• Software• U-center v.21.05• Data logging and viewing software from u-blox. Necessary to log and set-up
u-blox receivers• https://www.u-blox.com/en/product/u-center• Also, u-center 2 v.21.08 is available. You may try it, but we use u-center forexercise.

• RTKLIB• RTKLIB is very powerful software for RTK and PPP. It has many functions fordata conversion, data logging for RTK, DGPs etc.
• RTKLIB V. 2.4.3 b34• http://www.rtklib.com/• https://github.com/tomojitakasu/RTKLIB_bin/tree/rtklib_2.4.3

Download this one• RTKDROID

1. Select Code• https://home.csis.u-tokyo.ac.jp/~dinesh/LCHAR.htm• RTK Software based on RTKLIB for android device.
• Only for use with u-blox M8T, M8P or F9P receivers connected to an android
device• MAD-WIN / MAD-PI / MADROID• MAD-WIN is for MADOCA-PPP processing for high-accuracy for Windows PC.
• Google drive link will be provided to download software

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

2. Download ZIP

Slide : 55

Request for HW/SW• MADOCA Receiver Systems are distributed to overseas universities for joint
research and pilot projects• Includes HW and SW• Signing of MTA (Material Transfer Agreement) Document is necessary for HW• If only SW is required, please send request through• https://home.csis.u-tokyo.ac.jp/~dinesh/LCHAR.htm• SW is provided under the understanding that the recipients provide feedbacks
and some sample data
• Feedbacks are necessary to improve and debug the products

2021/09/22 9:16 PM

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

Slide : 56

MAD-WIN / MAD-PI User Interface
A

C

B

GNSS Receiver

Case A

Connect Receiver
Directly

Connect MADOCA
Receiver DirectlyCase B

Connect Receiver
Directly

Get MADOCA
correction data
through NTRIPConnect Receiverthough NTRIP

Get MADOCA
correction data
through NTRIPConnect Receiverthough NTRIPConnect MADOCA
Receiver Directly

Selection Settingin the Program

RX and DX

RX andOnline (MADOCA)

D
Case C

Case D2021/09/22 9:16 PM

MADOCA Correction
Data

Cases

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

Online andOnline (MADOCA)

Online and DX

Slide : 57

MADOCA PPP Test Results

2021/09/22 9:16 PM

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

Slide : 58

MADOCA PPP Test Results

2021/09/22 9:16 PM

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

Slide : 59

MADOCA PPP Test Results

2021/09/22 9:16 PM

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

Slide : 60

MADOCA PPP Test Results (24 hours)

2021/09/22 9:16 PM

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

Slide : 61

MADOCA PPP Test Results (24 hours)

2021/09/22 9:16 PM

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

Slide : 62

MADROID: MADOCA with Android Device

2021/09/22 9:16 PM

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

Slide : 63

MADROID: MADOCA with Android Device

2021/09/22 9:16 PM

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

Slide : 64

MADROID: PPP-RTK Test

2021/09/22 9:16 PM

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

Slide : 65

Low-Cost MADOCA Receiver for Sea-Level Rise Measurement

Source: Technical Report, GNSS/QZSS MADOCA PPP Data Acquisition for Sea Level Rise Measurement, DR. ROSALIE B. REYES, UP DGE and Project Leader, CLSR-Phil Project2021/09/22 9:16 PM

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

Slide : 66

GNSS Technology Promotion Activities

2021/09/22 9:16 PM

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

Slide : 67

GNSS Trainings, Workshops and Seminars• Conduct GNSS Trainings, Workshops and Seminars••

Basically in Asian countries•

Indonesia, Laos, Malaysia, Myanmar, Nepal, Thailand, The Philippines, Vietnam•

Bangladesh, India, Singapore, Sri Lanka, Azerbaijan, Mongolia (planned in 2020 but postponed due to COVID)

Also, Some African Countries•

Mozambique, Rwanda, Egypt• Regular Training is conducted in January every year with support from ICG/UNOOSA•

Training in 2018, 2019, 2020, 2021 (Online Only due to COVID)••

https://home.csis.u-tokyo.ac.jp/~dinesh/GNSS_Train.htm

Training in 2022 (Hybrid Format)•

On-Site training will be held in Pokhara City, Nepal•

Limited travel funding is available for international participants (Depends on COVID situation)

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

Slide : 68

RPD (Rapid Prototype Development) Challenge•

RPD Challenge is held every year for the past few years in collaboration with MGA, Japan.

•

RPD Challenge is a platform to bring your ideas into prototypes.

•

Experts in various fields assist you to shape-up your ideas into a working prototype system

2021/09/22 9:16 PM

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

Slide : 69

Summary and Future Plans• QZSS provides unique services for Early Warning System and High-Accuracy Positioning.

• We have developed Low-Cost MADOCA receiver systems• MAD-WIN, MAD-PI and MADROID• MAD-PI will be improved for remote data logging.

• We will integration of current system with other systems• Traffic monitoring, EWS Application, GIS data collection tool, ……..

• Trainings, Seminars, Workshops and Joint Projects with foreign universities will be conducted• Please join our programs for further promotion of the technology in the region• We share GNSS data from different types of receivers• Data from high-end survey grade receivers to low-cost receivers are available upon request

Refer https://home.csis.u-tokyo.ac.jp/~dinesh/ for more information.

2021/09/22 9:16 PM

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

Slide : 70