1

Introduction of Bridge Method

Between RTK and RTK-PPP

for their Co-prosperity

Nov. 2016

Izumi MIKAMI, Koki ASARI, and Masayuki SAITO

Satellite Positioning Research & Application Center（SPAC)

Positioning Signal Command & Telemetry

Ground segment

Monitor Stations Control Stations

Control Center

(1) JAXA HP：http://www.satnavi.jaxa.jp/project/qzss/index.html (2) Lockheed Martin HP：http://www.lockheedmartin.com/us/products/gps.html

(3) ESA HP：http://www.esa.int/Our_Activities/Navigation/Galileo/What_is_Galileo (4) CAST (Spaceflight 101 HP：ttp://spaceflight101.com/long-

march-3a-launches-beidou-2-satellite/ ) (5) Reshetnev HP：http://www.iss-reshetnev.com/spacecraft/spacecraft-navigation/glonass-m

(6) ISRO HP：http://www.isro.gov.in/Spacecraft/irnss-1g

GPS(2)

(USA)

QZSS(1)

(JPA)

GALILEO(3)

(EU)

Space segment

IRNSS(6)

(India)

GLONASS(5)

(Russia)

BeiDou(4)

(CHINA)

2

User Segment

Concept of GNSS (Global Navigation Satellite System)

GNSS is infrastructure at both space and ground segments. The user can measure self position on real-time

basis using ranging signals sent from GNSS.

Positioning Signal

QZSS Control

Center

QZSS

GNSS

National CORS (Continuous Operating

Ranging Systems)

Augmentation Data Server

Uplink

Users QZSS Control

& Monitor Station

Cellphone Net.

QZSS (Quasi-Zenith Satellite System) Navigation in JPN

Broad-

cast

: Augmentation Signal /Augmentation Data

: Ranging Signal

: Observation Data from National CORS

Signal Carrier Band

(MHz) Channel PRN Code, Modulation Method Signal Contents

L1C/A

1575.42

- Same coding as GPS L1C/A, BPSK(1) Ranging signal same as L1C/A, 50bps/50sps

L1C L1CD Same coding as GPS L1C, BOC(1,1) Ranging signal same as L1C, 50bps/100sps

L1CP Same coding as L1C, TMBOC Pilot signal

L1S L1S Same coding as GPS 1C/A, BPSK(1) Sub-meter class augmentation signal & Short message,

250bps/500sps

L1Sb L1Sb BPSK(1) SBAS Broadcasting service (GEO satellite only)

L2C 1226.60 - Same coding as GPS L2C,

BPSK(1)

L2C(CM) Ranging signal same as GPS L2C, 25bps/50sps

L2C(CL)

L5

1176.45

Ich Same coding as GPS L5C, BPSK(10) Ranging signal same as GPS L5C,50bps/100sps

Qch Same coding as GPS L5C, BPSK(10) Data less

L5S - QPSK(10) Positioning technology verification for QZO satellites)

L6

1278.75 L6b Kasami Coding, BPSK(5) Centi-meter class augmentation signal, 2000bps/250sps

S 2GHz band - - Personnel Safety Check service (GEO satellite)

4

QZSS Signal Assignment

5

Principle of RTK (Real Time Kinematic)-GPS

(Position of BS)

(Observation data at BS)

Base Station (BS) RTK User

Wireles transmission

RTK

-mm to cm class accuracy by relative measurement with respect to Base Station position. -BS is needed for each RTK user. -BS position must be pre-determined. -Wireless transmission of observation data of BS and its position is needed. -No other infrastructure is needed.

6

GNSS Satellite

Quasi-Zenith Satellite

National CORS RTK User

National CORS

National CORS

National CORS

VRS Server (Virtual Reference Point Generator)

Ranging Signal

GNSS Satellite GNSS Satellite GNSS Satellite

Principle of Network RTK-VRS (Virtual Reference System)

Cm class Positioning

-No Base-station is needed -VRS server is needed as infra structure. -Bidirectional communication via cell phone network is necessary between user and VRS server. -VRS server send position of Virtual Base Station and its observation data normally via cell phone network.

7

GNSS Satellite

Quasi-Zenith Satellite

National CORS User

National CORS

National CORS

National CORS

Cm class Positioning

SSR Server (Augmentation Data Generator)

Augmentation Signal Ranging Signal

GNSS Satellite GNSS Satellite GNSS Satellite

-No Base-station is needed. -SSR server is needed as infra-structure. -User can receive augmentation data free of charge from QZSS in addition to normal ranging signals from GNSS, and can enjoy cm class point positioning.

Principle of RTK-PPP(Precise Point Positioning)

8

Potential Users of QZSS Service and Coverage

-Normally understood that Augmentation data are irrelevant to RTK users.

-Can’t RTK users enjoy Augmentation data from QZSS free of charge?

If existing RTK equipment can accept augmentation data, a large number of new users would be born! ?

Augmentation signal　Ｌ6

(Augmentation data for RTK-PPP)No good Good

Signal Broadcasted from QZSS RTK Users New RTK-PPP Users

Ranging signal　(Ｌ１／L２)

(Compatible with GPS, Galileo）Good Good

-Should RTK users continuously pay for communication and/or Base Station?

9

RTK-VRS, RTK-GPS and RTK-PPP in the Field

From Field test report by Hokkaido Univ. (& SPAC), Oct. 15,2014

LEX Receiver

(RTK-PPP)

Robot Controller

X-Y

Err

or

(m)

X-Y

Err

or

(m)

Drive distance (m) Drive distance (m)

QZSS continuous service is desired to improve situation.

RTK-PPP/RTK-VRS Test Result (Above)

-RTK-PPP (CMAS) showed better

accuracy than RTK-VRS.

Iwamizawa City voice on RTK-GPS

(Seed Planning, Market Research, Jul.27,2016)

-Due to many base stations, radio

signals interferes and tractor’s auto

driving is disabled.

-Windbreak trees disturb radio signal.

-Base station is expensive.

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Physical Meaning of RTK-GPS and RTK-PPP

-----(1)

A: Satllite unique errors

(clock, orbit, signal bias)

(Clock, circuit delay)

Base station

C: Receiver

unique errors

RTK user RTK-PPP user

B:Propagation pass errors

(ionosphere, troposphere）

RTK

Distance between two points

RTK-PPP

Sum of Augmentationdata from QZSS Distance between

two points

Assumed Point (Cooridinate obtained by point positioning)

Distance error due to A,B,C

Distance error due to A,B,C

Geometric distance (Calculated using Ephemeris

data and assumed point coordinate)

True distance between satellite & receiver

Lp by calculation

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Physical Meaning of RTK-GPS and RTK-PPP

-----(1)

A: Satllite unique errors

(clock, orbit, signal bias)

(Clock, circuit delay)

Base station

C: Receiver

unique errors

RTK user RTK-PPP user

B:Propagation pass errors

(ionosphere, troposphere）

RTK

Distance between two points

RTK-PPP

Sum of Augmentationdata from QZSS Distance between

two points

Assumed Point (Cooridinate obtained by point positioning)

Distance error due to A,B,C

Distance error due to A,B,C

Geometric distance (Calculated using Ephemeris

data and assumed point coordinate)

True distance between satellite & receiver

If L6 receiver can generate 𝐿𝑝 by right member calculation of Eq. (1), base station can be substituted with L6 receiver, and RTK user can no longer needs base station and VRS data transmission. Named “L6 adopter”

Lp by calculation

Augmentation Signal L1/L2

RTK positioningcoordinate

Self coordinate by point positioning

Generated observation data Self coordinate by point positioning

Ephemeris data

RTKObservation

datagenerator

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L6 Adapter Concept Case 1 : When RTK side can send Ephemeris data and self coordinate

Case 2 : When RTK side cannot send Ephemeris data and self coordinate

Augmentation Signal L1/L2

L1

Generated observation data Self coordinate by point positioning

RTK positioningcoordinateRTK

Observationdata

generator

wired

wired

Patent application submitted

13

Conclusions

1. Verified RTK users can use QZSS augmentation data.

2. L6 adopter can act as attachment to existing RTK equipment as well as component

of new RTK product.

3. Several technical problems occurring in the field, associated with radio transmission

in RTK-GPS, can be resolved by L6 adopter and QZSS augmentation data.

4. Radio transmission cost, base station cost, and other cost necessary for RTK-VRS

& RTK-GPS system can no longer become necessary after use of L6 adopter.

Therefore, L6 adopter must be attractively lower-costed than these costs.

5. If transmitting cm class augmentation data via ground system, say, cell phone

network, data volume becomes far less than those of RTK-VRS, which reduce

transmission cost significantly.

6. RTK-PPP method is deemed rather difficult to understand and hard to apply to

product. For RTK equipment users and manufacturers, L6 adopter may eliminate

their study effort and minimize development time and cost.

Hope this “bridge method” can lower technical barrier of RTK-PPP for

users and act as co-prosperity driver with conventional RTK method.

THANKS FOR YOUR KIND ATTENTION!