Part V Centimeter-Level Instantaneous Long-Range RTK: Methodology, Algorithms and Application

Part V

Centimeter-Level Instantaneous Long-Range RTK:

Methodology, Algorithms and Application

GS894G

Presentation Outline

Network RTK – Concept and Benefits

Research Objectives

The MPGPS™ Software

Methodology and Algorithms

Experiments and Test Results

Summary and Conclusions

Current and Future Developments


Traditional RTK limitations (single baseline) Limited to short distances (~10 km)

Ionospheric and tropospheric refraction are the main error sources

Network RTK Atmospheric corrections are evaluated in the

network and broadcast to the user receiver location Single or multi-baseline instantaneous rover solution Long distances – over 100 km Centimeter-level accuracy Suitable for geodetic, surveying and navigation

applications Takes advantage of already available network GPS

infrastructure


Instantaneous RTKAdvantages Due to epoch independence, resistant to negative

effects, such as:Cycle slips and loss of lock

No initialization required for short/medium baselines (~< 50 km)

Short initialization (a few epochs) for longer baselines (~> 50 km)

Provides cm-level accuracy

Disadvantages Challenging ambiguity resolution and validation for

long baselines

instantaneous = single-epoch

Research Objectives

Develop and evaluate state-of-the-art methodology and algorithms for cm-level long-range instantaneous RTK GPS

Analyze the infrastructure necessary to support long-range instantaneous RTK GPS

Investigate atmospheric correction accuracy obtained from GPS reference network with station separation of 100-200 km supporting long-range RTK

MPGPS™ Multi Purpose GPS Processing Software

Developed at Ohio State University (OSU)

Positioning Modules Long-range instantaneous RTK GPS Rapid-static Static Multi-station DGPS Precise point positioning (PPP)

Atmospheric Modules Ionosphere modeling and mapping Troposphere modeling

Positioning Solutions Single-baseline Multi-baseline (network) Stand-alone

Methodology - Functional Model (DD)

1, 1 1,

2 22, 1 2 2 2,

1,

2,

( ) 0

( ) ( / ) 0

( ) 0

(

kl kl k l k l kl klij ij i i i i j j j j ij ij

kl kl k l k l kl klij ij i i i i j j j j ij ij

kl kl k l k l klij ij i i i i j j j j ij

kl kl k l kij ij i i i i j

T T T T I N

T T T T I N

P T T T T I

P T T

2 21 2) ( / ) 0l kl

j j j ijT T I

- satellite indexes

- station indexes

- DD phase and code observation on frequency n

- DD geometric distance

- tropospheric total zenith delay (TZD)

- troposphere mapping function

- DD ionospheric delay

- GPS frequencies on L1 and L2

- GPS frequency wavelengths on L1 and L2

- carrier phase ambiguities

,i j

, ,kln ij ,

kln ijPklij

,i jT

kiklijI

1 2,

1 2,

1, 2,,kl klij ijN N

,k l

All parameters in the mathematical model are considered

pseudo-observations with a priori information (σ = 0 ÷ )

Sequential Generalized Least Squares (GLS)

( , ) 0b bF XF L L

bXL

bFL - instantaneous parameters (e.g., ionospheric

delays)- accumulated parameters (e.g., ambiguities)

Two characteristic groups of interest:

Flexibility, easy implementation of:

stochastic constraints fixed constraints weighted parameters Filters (e.g., forward, backward)

Methodology - Adjustment Model

0 FbFX

bFF WLBLB

Methodology - Network Solution

Network correction generation Precisely known reference station coordinates Double-difference (DD) ionospheric delay estimation and

decomposition to zero-difference (ZD) Single layer model (SLM) ionosphere approximation Tropospheric total zenith delay (TZD) estimation

Ambiguity resolution (AR) Least square AMBiguity Decorrelation Algorithm

(LAMBDA)

Validation W-ratio and success-rate

Unknowns DD Ionospheric delays, Tropospheric TZD per station, DD

ambiguities

The network corrections are broadcast to the rover in a form of a grid


Ionospheric delay decomposition

n-2 linearly independent DD observation equations for an individual baseline and n ZDs, thus rigorous decomposition is not possible

Solutions

Introduce additional independent constraints on at least two ZD delay parameters

Introduce loose constraints to the diagonal of the normal matrix

Both methods are numerically identical

However, the first method results in an “unbiased” estimate while the second one provides a “biased” estimate in the least squares sense


Single layer model (SLM) ionosphere approximation

Slant ionospheric delays estimation from dual-frequency GPS data at the permanent stations

Slant ionospheric delays conversion to vertical total electron content (VTEC) at ionosphere pierce points (IPPs)

Kriging interpolation to produce LIM in a form of a grid using the calculated vertical TEC values at IPPs


SLM assumes that all free electrons are contained

in a shell of infinitesimal thickness at altitude H

z - zenith angle

H - SLM height

R - Earth radius

SLM – Single Layer Model

1 TECU = 1016 ellectron/m2

= 0.162 m delay/advance

Methodology - Rover Solution

Single or multi-baseline mode

Step one – short on-the-fly (OTF) initialization (a few epochs)

Ionospheric and tropospheric delays are provided by the network to initiate the rover solution

Step two – instantaneous (single-epoch)

DD ionospheric delays from the previous correctly resolved epoch are applied in the rover solution as a prediction

TZD provided from the network

Unknowns

Rover position and ambiguities

The DD ionospheric delays and TZD are tightly constrained in the GLS adjustment

Experiments and Test Results

1. Ionospheric model comparison (Ohio CORS)

Quality test of several ionosphere modeling techniques derived from GPS permanent tracking network data

Local – MPGPS-NR (network RTK) Regional – NGS MCON and NGS MAGIC Global ionospheric models – IGS global ionosphere map

(GIM)

2. Instantaneous long-range RTK analysis (Ohio CORS)

Distances between reference stations ~200 km Distances to the rover ~100 km

3. Network RTK in the state of Israel - GIL network (GPS in Israel)

The impact of the ionospheric correction latency on long-baseline instantaneous kinematic GPS positioning

Experiments and Test Results (1)

The ionospheric models

MPGPS™-NR — network RTK (NR) dual frequency carrier phase-based model, decomposed from DD ionospheric delays; single layer; local – uses several stations closest to the rover

IGS GIM — international GPS Service (IGS) global ionospheric map (GIM); single layer; global - ~200 stations

NGS ICON — absolute model based on undifferenced dual-frequency ambiguous carrier phase data; single layer; regional - ~340 CORS stations (USA)

NGS MAGIC — carrier phase DD-based tomographic method; 3D; regional - ~150 CORS and IGS stations (USA)


Test data Ohio CORS, August 31, 2003

24-h data set was processed in 12 sessions, each 2-h long 30-s data sampling rate Predicted satellite orbits and clock corrections (IGS) Different reference satellite for each session Varying ionospheric total electron content (TEC) levels Varying GPS constellation KNTN CORS station was selected as rover for the

simulation

Network solutionatmospheric corrections

Rover baseline solution

Network map Baseline map

104km

109km124km

108km

KNTN

63km

98km

KNTN

LSBN

(rover)

Test area maps (Ohio CORS)



0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MPGPS-L4 (Reference "truth")

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MPGPS-NR

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

IGS GIM

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

ICON (NGS)

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MAGIC (NGS)

[m]

hours

Estimated and interpolated DD ionospheric correctionsfor the analyzed models, 24 h, KNTN-SIDN (60 km)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MPGPS-P4

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MPGPS-NR

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

IGS GIM

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

ICON (NGS)

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MAGIC (NGS)

[m]

hours

Experiments and test Results (1)

DD ionospheric residuals with respect to the reference “truth” MPGPS-L4

KNTN-SIDN (60 km), 24 h

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MPGPS-L4 (Reference "truth")

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MPGPS-NR

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

IGS GIM

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

ICON (NGS)

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MAGIC (NGS)

[m]

hours


Estimated and interpolated DD ionospheric correctionsfor the analyzed models, 24 h, KNTN-DFI (100 km)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MPGPS-P4

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MPGPS-NR

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

IGS GIM

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

ICON (NGS)

[m]

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

MAGIC (NGS)

[m]

hours

Experiments and Test results (1)

DD ionospheric residuals with respect to the reference “truth” MPGPS-L4

KNTN-DEFI (100 km), 24 h

Residuals in [%] below the cut-off 24 h

KNTN-SIDN (~60 km)KNTN-DEFI (~100 km)

±10 cm ±5 cm ±10 cm ±5 cm

MPGPS-NR99.394.299.394.2

IGS GIM94.971.481.754.3

ICON58.431.958.232.5

MAGIC98.083.390.167.1

Residual statistics (24h)

Ionospheric delay residual statistics 5 and 10 cm cut-off limits

± 5 cm = ~1/4 of a cycle (required for pure instantaneous)

± 10 cm = ~1/2 of a cycle


4 4.25 4.5 4.75 5 5.25 5.5 5.75 6

-0.2

-0.1

0

0.1

0.2

04:00 - 06:00 UTC

[m]

18 18.25 18.5 18.75 19 19.25 19.5 19.75 20

-0.2

-0.1

0

0.1

0.2

18:00 - 20:00 UTC

[m]

hours

neu

neu

4 4.25 4.5 4.75 5 5.25 5.5 5.75 6

-0.2

-0.1

0

0.1

0.2

04:00 06:00 UT

[m]

18 18.25 18.5 18.75 19 19.25 19.5 19.75 20

-0.2

-0.1

0

0.1

0.2

18:00 - 20:00 UTC

[m]

hours

Instantaneous RTK positioning, 2h sessions, KNTN-SIDN (~60 km)

neu

neu

n,e,u, residuals with respect to the known coordinates, KNTN-SIDN, 60 km

n,e,u, residuals with respect to the known coordinates, KNTN-DEFI, 100 km

Examples of instantaneous positioning after 3-epoch OTF initialization, MPGPS-NR


Summary and conclusions

Different ionospheric models were analyzed

• Varying TEC levels, generally quiet ionospheric conditions

• Varying GPS constellation

MPGPS-NR provided the best solution

• Can support instantaneous AR and high-accuracy positioning

Ionospheric correction accuracy of 1-6 cm (1 sigma)

Stochastic constraints in the GLS depend on the ionospheric activity level

Other models: lower rate of success of instantaneous AR


Test data Ohio CORS, August 31, 2003

Four two-hour sessions (daytime):

14 - 16 UT (10pm - 12pm LT)

16 - 18 UT (12pm - 14pm LT)

18 - 20 UT (14pm - 16pm LT)

20 - 22 UT (16am - 18pm LT)

30-second sampling rate (i.e., 120 epochs per session)

Predicted satellite orbits and clock corrections (IGS)

Distances between reference stations ~200 km

Distances to the rover >100 km

COLB CORS station was selected as rover for the simulation


Network solutionatmospheric corrections

Roverbaseline solution

Network map Baseline map

212 km

206 k

m

193 km

121 km

LSBN

(rover)

Test area maps (Ohio CORS)


Residuals (n,e,u ) with respect to the known coordinates, COLB-LEBA, 121

km,

and satellite visibility at station COLB

14-16 UT (10am-12pm LT) 16-18 UT (12pm-14pm LT)


50 100 150 200

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

Epochs

[m]

neu

50 100 150 200

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

Epochs

[m]

neu

Epochs

PR

N

50 100 150 200

2

4

6

8

10

12

14

16

18

20

22

Epochs

PR

N

50 100 150 200

5

10

15

20

25

30

Epochs

PR

N

50 100 150 200

5

10

15

20

25

30

10

20

30

40

50

60

18-20 UT (14pm-16pm LT) 20-22 UT (16pm-18-pm LT)


50 100 150 200

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

Epochs

[m]

neu

Epochs

PR

N

50 100 150 200

5

10

15

20

25

30

50 100 150 200

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

Epochs

[m]

neu

Epochs

PR

N

50 100 150 200

5

10

15

20

25

Epochs

PR

N

50 100 150 200

5

10

15

20

25

30

10

20

30

40

50

60

Residuals (n,e,u ) with respect to the known coordinates, COLB-LEBA, 121

km,

and satellite visibility at station COLB


A sub-network characterized by inter-station separation of ~200 km was chosen to generate the atmospheric corrections

The rover-reference stations distances are larger than 100 km

Although these large distances, centimeter-level instantaneous rover positioning was demonstrated in this simulation.

The vertical component is weaker than the horizontal ones, as expected

It may be concluded that 200 km separation between the GPS reference stations is a sufficient infrastructure for centimeter- level long range instantaneous RTK


Test data

GIL (GPS in Israel) permanent network, June 21, 2004

Four one-hour sessions:

01 - 02 UT ( 4am - 5am LT) - sunrise

09 - 10 UT (12am - 13pm LT) - noon

13 - 14 UT (16am - 17pm LT) - afternoon

17 - 19 UT (20am - 21pm LT) - sunset

10-second sampling rate (i.e., 360 epochs per session)

Predicted satellite orbits and clock corrections (IGS)

Distances between reference stations ~100-200 km

Distances to the rover ~50-100 km

GILB station was selected as rover for the simulation


Test area map (GIL network)

The network provides atmospheric corrections

to the rover (GILB)

The rover station does not contribute to the

atmospheric corrections

Distances Reference network:

110-180 km

To the rover:50, 85, 98 km

Station heights

37-1083 m

112 k

m

180 k

m

110 k

m

50 km

85 k

m

98

km

Roverh=507m

(37m)

(1083m)

(32m)


MPGPS-derived TEC Maps for the four analyzed sessions

33oE 34

oE 35

oE 36

oE 37

oE

29oN

30oN

31oN

32oN

33oN

34oN

TECU

5

10

15

20

25

30

33oE 34

oE 35

oE 36

oE 37

oE

29oN

30oN

31oN

32oN

33oN

34oN

TECU

5

10

15

20

25

30

33oE 34

oE 35

oE 36

oE 37

oE

29oN

30oN

31oN

32oN

33oN

34oN

TECU

5

10

15

20

25

30

33oE 34

oE 35

oE 36

oE 37

oE

29oN

30oN

31oN

32oN

33oN

34oN

TECU

5

10

15

20

25

30

4:30 am LT(sunrise)

lowest TEC highest

gradients

12:30 pm LT(noon)

highest TEClowest

gradients

16:30 pm LT(afternoon)

20:30 pm LT(sunset)


DD ionospheric delay residuals, interpolated vs. “true” (MPGPS-L4),

GILB-DRAG baseline (98 km)

50 100 150 200 250 300 350-0.15

-0.1

-0.05

0

0.05

0.1

0.15

Epochs

[m]

50 100 150 200 250 300 350-0.15

-0.1

-0.05

0

0.05

0.1

0.15

Epochs

[m]

50 100 150 200 250 300 350-0.15

-0.1

-0.05

0

0.05

0.1

0.15

Epochs

[m]

50 100 150 200 250 300 350-0.15

-0.1

-0.05

0

0.05

0.1

0.15

Epochs

[m]

4-5 am LTsunrise

12-13 pm LTnoon

16-17 pm LT - afternoon

20-21 pm LT sunset


5 cm is the accuracy limit

for pure instantaneous

DD ionospheric delay residuals (with respect to MPGPS-L4) for different latencies,

GILB-CSAR baseline (50 km), 4–5 am LT

50 100 150 200 250 300 350

-0.05

0

0.05

10s latency

50 100 150 200 250 300 350

-0.05

0

0.05

20s latency

50 100 150 200 250 300 350

-0.05

0

0.05

30s latency

50 100 150 200 250 300 350

-0.05

0

0.05

40s latency

DD

Ion

os

ph

eri

c r

es

idu

als

[m

]

50 100 150 200 250 300 350

-0.05

0

0.05

50s latency

50 100 150 200 250 300 350

-0.05

0

0.05

60s latency

50 100 150 200 250 300 350

-0.05

0

0.05

70s latency

50 100 150 200 250 300 350

-0.05

0

0.05

80s latency

Epochs50 100 150 200 250 300 350

-0.05

0

0.05

90s latency

The large residuals reflect the high gradients (sunrise)


Single-baseline RTK position residuals (n,e,u) with respect to the known coordinates,

GILB-CSAR (50 km), 4–5 am LT

50 100 150 200 250 300 350-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Epochs

[m]

neu

50 100 150 200 250 300 350-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Epochs

[m]

neu

-0.14 -0.1 -0.06 -0.02 0.02 0.06 0.1 0.14-0.14

-0.1

-0.06

-0.02

0.02

0.06

0.1

0.14

n [m]

e [m

]

-0.04 -0.02 0 0.02 0.04

-0.04

-0.02

0

0.02

0.04

n [m]

e [m

]90 s latency, single-baseline

unresolved ambiguities

Experiments and Test results (3)

10 s latency, single-baseline

Multi-baseline RTK position residuals (n,e,u) with respect to the known coordinates,

GILB-CSAR (50 km) and GILB-ELRO (85), 4–5 am LT

-0.04 -0.02 0 0.02 0.04

-0.04

-0.02

0

0.02

0.04

n [m]

e [m

]

50 100 150 200 250 300 350-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Epochs

[m]

neu

50 100 150 200 250 300 350-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Epochs

[m]

neu

-0.04 -0.02 0 0.02 0.04

-0.04

-0.02

0

0.02

0.04

n [m]

e [m

]90 s latency, multi-baseline90 s latency, single-baseline


DD ionospheric delay residuals with respect to MPGPS-L4 for different latencies,

GILB-DRAG baseline (98 km), 12–13 am LT

50 100 150 200 250 300 350

-0.05

0

0.05

10s latency

50 100 150 200 250 300 350

-0.05

0

0.05

20s latency

50 100 150 200 250 300 350

-0.05

0

0.05

30s latency

50 100 150 200 250 300 350

-0.05

0

0.05

40s latency

DD

Ion

os

ph

eri

c r

es

idu

als

[m

]

50 100 150 200 250 300 350

-0.05

0

0.05

50s latency

50 100 150 200 250 300 350

-0.05

0

0.05

60s latency

50 100 150 200 250 300 350

-0.05

0

0.05

70s latency

50 100 150 200 250 300 350

-0.05

0

0.05

80s latency

Epochs50 100 150 200 250 300 350

-0.05

0

0.05

90s latency

The small residuals reflect the low gradients (noon)


Single-baseline RTK position residuals (n,e,u) with respect to the known coordinates,

GILB-DRAG (98 km), 12–13 am LT

50 100 150 200 250 300 350-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Epochs

[m]

neu

-0.04 -0.02 0 0.02 0.04

-0.04

-0.02

0

0.02

0.04

n [m]

e [m

]

50 100 150 200 250 300 350-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Epochs

[m]

neu

-0.04 -0.02 0 0.02 0.04

-0.04

-0.02

0

0.02

0.04

n [m]

e [m

]

10 s latency 90 s latency


Statistics: instantaneous AR success rate

50 km98 km

Latency/Session

30 s60 s90 s30 s60 s90 s

sunrise100.0100.099.2100.0100.095.8

noon100.0100.0100.0100.0100.0100.0

afternoon100.0100.0100.0100.0100.0100.0

sunset100.0100.0100.0100.0100.097.2

Example AR success (%), single-baseline solution

Note: the multi-base solution solved 100% of the ambiguities



The interpolated ionospheric correction accuracy may not always be sufficient to assure pure instantaneous AR in the baseline mode (more than 5 cm)

It was demonstrated that when the single-baseline solution fails and the multi-baseline solution takes over, instantaneous AR can be sustained

For the existing ionospheric conditions, network configuration and processed baseline lengths (~100 km), 90-second latency seems to be a limit for reliable instantaneous AR

Once the ambiguities are correctly resolved, centimeter-level positioning can be assured over long baselines (>100 km)

Again, the vertical component is weaker than the horizontal ones

The long-range instantaneous RTK module in the MPGPS™ software can provide cm-level rover position over long distances


Algorithm applications

Current OPUS-RS - Extending the NGS (National Geodetic Survey)

OPUS (On-line Positioning User Service) with rapid static capability, based on the MPGPS™ Network RTK algorithms Current requirement – 2-4 hours Future rapid static requirement – 10-15 minutes Predicted user number increase – about 10 times

ICON and MAGIC - Quality evaluation of the two NGS ionosphere models

Future Further analysis to fully asses the RTK algorithm capabilities

Longer latencies (up to a few minutes using multi-base solution)

Different ionospheric conditions (i.e., ionospheric storms) Longer baselines Real kinematic data

Part V Centimeter-Level Instantaneous Long-Range RTK: Methodology, Algorithms and Application

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Transcript of Part V Centimeter-Level Instantaneous Long-Range RTK: Methodology, Algorithms and Application