GNSS Online Lecture # 1
Lecture ID: WT-103-401
Lecture Topic: GNSS Data Processing in RTKLIB
Dinesh ManandharCenter for Spatial Information Science
The University of Tokyo
Contact Information: dinesh@iis.u-tokyo.ac.jp
11th May 2018
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 1

Webinar Information• Lecture Type : Webinar• Webinar ID : WT-103-401• Webinar Topic : GNSS Data Processing in RTKLIB• Technical Level : Intermediate• Pre-Requisite (Recommended):• Webinar ID : WT-101-101: Introduction to GNSS
• Webinar ID : WT-102-302: GNSS Field Survey• Or general knowledge about GNSS, field survey and data collection.

• Date : 11th MAY 2018 Friday, Time : 18:00 (JST) 09:00 (UTC)• Duration : 75 minutes• Resource Person : Dinesh Manandhar, Associate Professor, The University of Tokyo• This Webinar is Technical. We discuss the followings:(1) How to setup u-blox receiver to collect raw data for RTK(2) How to convert u-blox data into RINEX format(3) How to download base-station data from our ABN stations (NetR9)(4) How to process raw data for RTK using RTKLIB• Registration : https://gnss.peatix.com or https://s-gnss.peatix.com
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 2u-center Software Installation

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

Slide : 3

Install u-center Software• u-center is a software for u-blox receivers• Available for Windows and Android Device• It can also be used with other receivers that
output NMEA data

• Download the software from• https://www.u-blox.com/en/evaluation-software-and-tools• Install the software with driver• Select “Use Windows USB Serial Driver”• Follow the instructions• Connect u-blox receiver to one of the USB
ports. The device is now ready for use.

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

Slide : 4

Select COM Port toConnect the Receiver
Click here
This will show the COM port on which u-blox
receiver is connected
Select the port which is connected to u-blox
Hint:
If you don’t know which COM port is used for
u-blox:* disconnect the receiver* check COM ports now• Re-connect the receiver• check the COM ports
You will see one new COM port now.
Select this COM port to connect the receiver

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

Slide : 5

Troubleshooting COM Port Setting

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

Slide : 6

U-center 8.27

U-center 8.29

Run Device Manager
You will see SENSORS– u-blox GNSS Location Sensor
If your receiver doesn’t workwith this setting, update thisdriver
Instructions for update are givenin the next few slides

After update you will see(1) U-blox Virtual COM Port(COM ID) OR(2) USB Serial Device (COM ID)(3) Repeat update process for
all USB ports that you wantto connect the u-blox
receiver(4) Otherwise it will use VirtualCOM port
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 7

Click Mouse Right Button

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

Slide : 8

Select this option

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

Slide : 9

Select this option

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

Slide : 10

Select this option

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

Slide : 11

A new COM Port
will be installed
Next, Remove usb cable and re-connect once
again. You should see the same COM port
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 12

Run u-center andselect COM Port.
You will see the
New COM port
here. Select it.

It should work now
See the COM Portand green lightblinking here

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

Slide : 13

u-Blox Receiver Setup to
Log Raw Data for RTK

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

Slide : 14

Output Data Types from a GPS Receiver• PVT Data

• Position, Velocity and Time
• All receivers output these data
• Data format is NMEA

• Raw Data

• Pseudorange, Carrier-phase and Doppler• Required for RTK• Some receivers output these data
• File format may be proprietary or
RINEX Observation File

• Navigation Message Data

• Satellite Ephemeris, Almanac and Clock
Data, Satellite Health Status etc.
• Required for RTK• Satellite Related Data

• Number and Type of Satellites, Azimuth,
Elevation, Satellite Types and Signals• Many Receivers output these data
• Data Format is NMEA

• Signal Quality Data
• C/No or SNR• Other Data

• Noise related data
• Receiver specific proprietary
information• File format may be proprietary or RINEX Navigation
File
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 15

Connect receiver by selecting COM port

Select COM Port

Select Speed 115200

If COM port is open properly,
You will see Green color flashingDinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 16

Select GNSS
Config Tab

Enable QZSS &L1SAIF

Enable either Beidou or Glonass.
Both systems can’t be enabled at the same time.

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

Slide : 17

Select RAWX

This logs raw data for each
visible satellite like:
Pseudorange
CarrierPhase
Doppler
SNR (C/No) etc

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

Slide : 18

Select SFRBX
Select Enable

This logs Navigation Data
bits for each visible satellite

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

Slide : 19

After setting all the parameters, save it to EPROM by
selecting RECEIVER-> ACTION -> SAVE CONFIG

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

Slide : 20

After setting all the parameters, save the output by
selecting FILE-> SAVE or by clicking RED Record circle.

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

Slide : 21

Output rate can be changed from
1Hz to 5Hz or 10Hz
Change UBX-CFG-RATE parameter
ChangeMeasurement Period to 200 [ms] for 5[Hz]outputDinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

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Convert from UBX format to RINEX

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

Slide : 23

RTKLIB Main Menu, Ver 2.4.3 b26

RTKVIDEO
RTKGETRTKPLOTRTKNAVI

RTKCONVNTRIPBROWSERSTRSVRRTKPOST

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

Slide : 24

Convert from UBX to RINEX

2
3

1

4

5
Select RTKCONV
Select UBX file
Select Format

6
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

7
Slide : 25

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

Slide : 26

1

Select RINEX Version

Select Satellite Types

2
Select RAW Data Types
C: Codephase
L: Carrierphase
D: Doppler
S: SNR

3

4

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

Slide : 27

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

Slide : 28

Check RINEX Data

RTKVIDEO
RTKGETRTKPLOTRTKNAVI

RTKCONVNTRIPBROWSERSTRSVRRTKPOST

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

Slide : 29

RTKPLOT to Check Data

Click this button

Use RTKPLOT
Drag and Drop files here
RINEX files
NMEA FileUBX file etc

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

Slide : 30

Visible Satellites and Skyplot

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

Slide : 31

SNR, Multipath and Elevation for J03 and G01 Satellites

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

Slide : 32

How to Get Base-Station Data

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

Slide : 33

Accessing Base-Station Data
• For Real-Time RTK• Get NTRIP Address• IP Address• Port ID• Mount Point• Login ID• Password• For Post-Processing RTK• IP Address• Login ID• Password• Select the files• Select the data format• Download the files

Always request Base-station data in RINEX format if possible.
This will save your time in pre-processing of proprietary data formats
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 34

Sample of Data Files in NetR9

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

Slide : 35

Select Required Data Type and Data

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

Slide : 36

RTK Post-Processing

RTKVIDEO
RTKGETRTKPLOTRTKNAVI

RTKCONVNTRIPBROWSERSTRSVRRTKPOST

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

Slide : 37

RTK Post-Processing• Prepare Data
• Base Station Data
• RINEX OBS File
• RINEX NAV File

• Rover (User) Data
• RINEX OBS File• Select Rover Observation Data
• Select Base Observation Data
• Select Navigation Data

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

Slide : 38

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

Slide : 39

35.66633461

139.7922008

59.741
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 40

One Hour RTK Post-processing output

Base
Rover

: NetR9: NetR9Show only RTK FIX
Data

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

Slide : 41

One Hour RTK Post-processing output

Base
Rover

: NetR9: U-bloxM8P

Show only RTK FIX
Data

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

Slide : 42

Base
Rover

: U-bloxM8P: U-bloxM8P

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

Slide : 43

Base: NetR9 (High-end)
Rover: NetR9 (high-end)

Position Output Comparison
between(a) High-end Base and High-end Rover(b) High-end Base and Low-end Rover
Base: NetR9 (high-end)
Rover: U-blox M8P (Low-end)

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

Slide : 44

Reference Slides

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

Slide : 45

Data Formats: NMEA, RINEX

References: https://www.nmea.org/
http://freenmea.net/docs
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 46

National Marine Electronics Association (NMEA) Format• NMEA is format to output measurement data from a sensor in a
pre-defined format in ASCII• In the case of GPS, It output GPS position, velocity, time andsatellite related data
• NMEA sentences (output) begins with a “Talker ID” and“Message Description”• Example: $GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47• “$GP” is Talker ID• “GGA” is Message Description to indicate for Position Data
Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 47

NMEA Data Format
GGA - Fix data which provide 3D location and accuracy data.
$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47
Where: GGA Global Positioning System Fix Data
123519Fix taken at 12:35:19 UTC
4807.038, N
Latitude 48 deg 07.038' N
01131.000, E
Longitude 11 deg 31.000' E
1 Fix quality:
0 = invalid ,1 = GPS fix (SPS),
2 = DGPS fix,
3 = PPS fix,
4 = Real Time Kinematic
5 = Float RTK
6 = estimated (dead reckoning) (2.3 feature)
7 = Manual input mode
8 = Simulation mode
08
Number of satellites being tracked
0.9
Horizontal dilution of position
545.4,M
Altitude, Meters, above mean sea level
46.9,M
Height of geoid (mean sea level) above WGS84 ellipsoid(empty field)
time in seconds since last DGPS update (empty field) DGPS station ID number*47
the checksum data, always begins with *Dinesh Manandhar, CSIS, The University of Tokyo, dinesh@iis.u-tokyo.ac.jp

Slide : 48

RINEX Data Format• Receiver Independent Exchange Format (RINEX) is a data exchange format for
raw satellite data among different types of receivers.

• Different types of receivers may output position and raw data in proprietary formats• For post-processing of data using DGPS or RTK it is necessary to use data fromdifferent types of receivers. A common data format is necessary for this purpose.
• Example: How to post process data from Trimble, Novatel and Septenrtio receivers tocompute a position?

• RINEX only provides Raw Data. It does not provide position output.
• User has to post-process RINEX data to compute position• Raw data consists of Pseudorage, Carrierphase, Doppler, SNR• RINEX basically consists of two data types• “*.*N” file for Satellite and Ephemeris Related data.
• Also called Navigation Data

• “*.*O” file for Signal Observation Data like Pseudorange, Carrier Phase, Doppler, SNR• Also called Observation Data

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

Slide : 49

RINEX “N” File for GPS

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

Slide : 50

RINEX “O” File GPS, GLONASS, GALILEO, QZSS, SBAS

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

Slide : 51

RINEX “O” File, Continued from previous slide

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

Slide : 52

Additional Information

Please visit websites
For Webinar: http://www.csis.u-tokyo.ac.jp/~dinesh/WEBINAR.htm
https://gnss.peatix.com
Main Page : http://www.csis.u-tokyo.ac.jp/~dinesh/
Other: https://www.youtube.com/watch?v=JaicV8egzFo

Contact:
dinesh@iis.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

Slide : 53