Net_Diff

Net_Diff is a software for GNSS Download, Positioning and Analysis.

It enables users to perform SPP/PPP/PPP-AR/DSPP/DPPP/RTK/PPP-RTK. All the signals of the current GPS/GLONASS/BeiDou/Galileo/QZSS/IRNSS are supported from single-frequency to triple-frequency. It can also be applied in SPP/PPP with BeiDou augmentation information (authorized user).

It supports data analysis, including coordinate plotting, coordinate comparison, satellite number, PDOP, satellite skyview, satellite visibility, cycleslip, troposphere, ionosphere, observation minus correction, positioning residuals plotting and KML file writing.

It provides GNS observation data and products download from many public FTP servers.

It also provides some useful tools such as time and coordinate system transferring, RTCM data receiving through Ntrip and TCP/IP, raw data converting, RINEX editing, ssr dumping, CLALIB and so on.

It provides a simple satellite orbit simulation.

Moreover, it supports multi-station PPP, clock estimation, DCB estimation based on GNSS net (authorized user).

If you have problem in downloading Net_Diff, it is probably due to the Great Fire Wall (https://sardingfish.top/2020/04/11/GithubDownload/). In this case, you can turn to here for downloading: http://center.shao.ac.cn/shao_gnss_ac/

We also provide online PPP/RTK Service:

http://center.shao.ac.cn/shao_gnss_ac/

http://129.211.69.159:8090/Main.aspx

How to install:

1. Install gzip

   Click gzip-1.3.12-1-setup.exe and install gzip. 
   
   For example, after install it, gzip.exe is under C:\Program Files (x86)\GnuWin32\bin\
   

2. Install Net_Diff

   a) If you have installed MATLAB R2017a or MATLAB Runtime version 9.2 (R2017a) on your computer.

   Open /for_redistribution_files_only/ and click Net_Diff.exe
   

   b) If not.

   Open /for_redistribution/ and click Net_Diff_Installer_web.exe to install MATLAB Runtime and Net_Diff.exe
   
   Please keep your computer connected to internet while installing.
   
   It will take a few minutes to download MATLAB Runtime, please be patient.
   
   If error occurs in connecting MathWorks, try to rerun the installer, or check the firewall, proxy server or virus scanner settings.
   
   If error occurs in downloading MATLAB Runtime 9.2, please download or update it by hand from:        
   https://ww2.mathworks.cn/products/compiler/matlab-runtime.html
   
   After installation, you can find the execute file from the installed program directory, for example C:\Program Files\Net_Diff\application\. 
   

3. Set environment variables

   This step is to automatically unzip the downloaded file and convert the crx file to rinex file if you want to download or update files in Net_Diff. 
   
   To do this, please add the path of gzip.exe (C:\Program Files (x86)\GnuWin32\bin\) and crx2rnx.exe (C:\Program Files\Net_Diff\application\) to the PATH of system environment variables on your computer:
   
   My computer-->Properties-->Advanced system setting-->Environment variables-->Edit the PATH environment variable-->Add path
   
   If you have problems in setting the environment variables, you can simply copy C:\Program Files (x86)\GnuWin32\bin\gzip.exe to C:\Program Files\Net_Diff\application and run Net_Diff from C:\Net_Diff\ application. 
   When running Net_Diff from the Windows Start or the Desktop, you should also copy C:\Program Files (x86)\GnuWin32\bin\gzip.exe and C:\Program Files\Net_Diff\application\crx2rnx.exe to the folder of C:\Windows\System32 or Desktop.
   

Citations:

It is appreciated that if you cite Net_Diff with the following paper:

1. Yize Zhang. Research on Real-time High Precision BeiDou Positioning Service System[J]. Acta Geodaetica et Cartographica Sinica, 2018,47(9):1293. DOI:10.11947/j.AGCS.2018.20170534
2. Yize Zhang, Junping Chen, Xiuqiang Gong, Qian Chen. The update of BDS-2 TGD and its impact on positioning[J]. Advances in Space Research, 2020, 65(11):2645-2661.
3. Yize Zhang, Nobuaki Kubo, Junping Chen, Jiexian Wang, Hu Wang. Initial Positioning Assessment of BDS New Satellites and New Signals[J]. Remote Sensing, 2019, 11(11): 1320.

Tips:

• 1. If you run Net_Diff from the Windows Start or Desktop, please select the correct directory of the EOP file, Ant File and GLO&Leap file in the Input folder (C:\Program Files\Net_Diff\application\Input) every time. Therefore, it is recommended to run Net_Diff from the execute file (You can also copy the folder of C:\Program Files\Net_Diff\application to any other directories).
• 2. If the directory of Net_Diff.exe is not allowed to write files, try to run Net_Diff.exe from the administrator.
• 3. When updating Net_Diff, you only need to copy the updated files in for_redistribution_files_only/ to C:\Program Files\Net_Diff\application. The updated files can also be found under the "release" tag.
• 4. As for the use of Net_Diff, please refer to the help document "A guide to use Net_Diff.pdf".
• 5. The document "A Comparison of Net_Diff and RTKLIB.pdf" compares the performance of Net_Diff and RTKLIB for a better understanding of Net_Diff.

For any problems or suggestions in using Net_Diff, please contact me ([email protected]) or join the QQ group: 838636621

Revision History:

V1.0

2018/07/24

1. Modify GUI in Analysis panel

2. Modify RTK fix and hold mode

3. Change GLONASS satellite number from 24 to 27

2018/07/25

1. Modify ISB model in PPP

2. Fix bugs of BeiDou PCO

2018/07/26

1. Fix bugs in GUI

2018/08/09

1. Modify GUI

2. Change selecting reference satellite method

3. Change settings in long baseline RTK

2018/08/17

1. Use traditional KF algorithm in long baseline RTK and change some settings

2. Modify Galileo F/Nav and I/Nav broadcast ephemeris selection

3. Add GLONASS in RTK float solution

2018/08/21

1. Change default ratio from 3 to 2

2. Fix bug of static long baseline RTK

2018/08/22

1. Fix bugs in GUI

2018/08/24

1. Change coordinate variance to 60m, modify outliers detection

2. Change troposphere constraint in long baseline RTK

2018/08/26

1. Modify partial AR

2018/08/27

1. Change settings for long baseline RTK

2018/08/30

1. Change selection of reference satellite in RTK

2. Improve outlier detection in RTK

3. Change Galileo max satellite number from 31 to 36

2018/09/03

1. Modify GUI

2018/09/06

1. Fix bugs in GUI

2. Add GPS L2C observation

V1.1

2018/09/13

1. Fix bugs when there are too few satellites while cycle slip in RTK

2. Support Doppler selection in GUI

2018/09/16

1. Support RINEX editing in GUI, modify GUI

2018/09/18

1. Support Time and Coordinate Transfer in GUI.

2. Support command line file input function for Net_Diff.

V1.2

2018/09/28

1. Fix bugs in static SPP

2. Fix bugs in GUI

3. Support multi-GNSS tight combined RTK

4. Support posfile output available for RTKPLOT.

5. Support Coordinate.txt appended after Control.txt

2018/09/29

1. Fix bugs in BDS WADS PPP mode

2. Modify GUI

2018/10/12

1. Fix bug in BeiDou PCO of C13 for gbm

2. Modify tightly combined RTK

3. Modify GUI

V1.3

2018/10/17

1. Support GLONASS AR in tightly or loosely combined RTK

2. Modify tightly combined RTK

3. Support Android raw data convert to RINEX

4. Modify GUI

2018/10/20

1. Fix bugs in non-L1L2 combination when using clock from sp3 file

2. Fix bugs tightly combined RTK

2018/11/08

1. Fix bugs of single system SPP when ISB setting is true

2. Fix bugs of SPP for outlier detection

3. Fix bugs of PCV correction for Galileo and QZSS

4. Fix bugs of loosely combined GLONASS RTK

5. Change maximum time difference of RTK to 30s

6. Modify GUI

V1.4

2018/11/16

1. Support mix-frequency combination on each satellite system (only available in GUI)

2. Support mix-observation combination on each satellite system (only available in GUI)

3. Support PPP-AR (only available in GUI)

4. Support undifferenced uncombined PPP (only available in GUI)

5. Add output of ionosphere correction in uncombined PPP

6. Add phase windup correction in RTK

7. Reduce matrix size to improve processing efficiency

8. Changeable cycle slip detection threshold

9. Fix bug in LAMBDA

10. Fix bug of Galileo PCO correction

11. Modify GUI

2018/11/19

1. Support triple-frequency undifferenced uncombined PPP (only available in GUI)

2. Change ionosphere initial value of undifferenced uncombined PPP

3. Fix bug of ionosphere correction when frequency combination is L2L3

4. Fix bug when cycle slip method is only LLI in RTK

5. Modify GUI

V1.5

2018/12/14

1. Support PPP-RTK (CLAS) (Authorized)

2. Change output file name for better parallel computing

3. Change threshold of outlier detection

4. Fix bug of IRNSS frequency

5. Modify GUI

2018/12/26

1. Support triple-frequency ionosphere-free PPP (only available in GUI)

2. Support Android dual-frequency multi-GNSS raw data converted to RINEX

3. Fix bug of BDS PCO using new atx file in triple frequency PPP

4. Turn off time restriction of BSX file

2018/12/27

1. Change maximum BeiDou satellite PRN to 37

2. Fix bug of satellite orbit value in sp3 file when it is 0.000

V1.6

2019/01/25

1. Support new signal of BDS (B1c/B2a) and GLONASS (G3), Galileo(E6), QZSS(L6)

2. Fix bug of doppler aided SPP/PPP

2019/02/04

1. Support user self-named file selection in GUI

2. Fix bug of GLONASS AR

3. Speed up efficiency of matrix inversion and least square solution.

2019/02/14

1. Add SNR depended stochastic model

2. Change elevation depended stochastic model in RTK, change phase noise from 1cm to 3mm

3. Fix bug of doppler aided RTK

4. Modify GUI

V1.7

2019/02/25

1. Support network PPP solution (Authorized)

2. Support loosely coupled PPP/INS and RTK/INS (Authorized)

3. Add threshold of success rate in AR

4. Add data-based and model-based combined AR

5. Fix bug of DCB correction for different frequency combination

2019/02/27

1. Add ionosphere compensate in long baseline RTK

2. Use I/Nav when F/Nav is unavaliable for Galileo

2019/03/08

1. Modify stochastic model of observations

2. Add DCB correction of L2C observation

2019/03/13

1. Add forward and backward combined RTK

2. Fix bug of GLONASS velocity calculation

3. Add ionosphere process noise setting in long baseline RTK

4. Fix bug of GBM products download error

5. Fix bug of uncombined PPP

2019/03/20

1. Modify tightly combined RTK

2. Modify elevation depended stochastic model

3. Fix bug of GNSS product downloading

2019/03/26

1. Modify BDS3 PPP

2. Fix bug of RTK

3. Fix bug of BDS3 DCB correction

2019/04/04

1. Fix bug of GLONASS IFB estimation in PPP

2. Modify EOP value selection and polar tide correction model

3. Change time difference tolerance of navigation ephemeris

4. Add WL elevation cutoff setting in RTK

5. Change ionosphere constraint and initial covariance in long baseline RTK

6. Modify GUI

2019/04/07

1. Change code and phase raw measurement noise to 0.3/0.003m

2. Improve PPP performance in severe environment

2019/04/09

1. Add QZSS code DISB estimation

2. Correct QZSS 1/4 cycle bias for Trimble receiver

3. Don't estimate GLONASS phase DISB when not fix GLONASS ambiguity

V1.8

2019/04/15

1. Support SSR correction based SPP/PPP

2. Support receive RTCM message from Ntrip (Adapt from goGPS)

3. Support dump RTCM SSR and conversion of various type of raw data to RINEX (Adapt from RTKLIB)

4. Change satellite velocity in ECEF

2019/05/16

1. Fix bug of receiver type checking

2. Fix bug of non-GPS non-L1L2 frequency DCB correction

3. Fix bug of real-time broadcast ephemeris downloading

4. Fix bug of using Wuhan ultra-rapid multi-GNSS products

5. Fix bug of GLONASS IFB estimation in multi-GNSS PPP

2019/05/22

1. Fix error of BDS observation data in RINEX 3.04 for JAVAD receiver

2019/06/07

1. Change BDS-3 PCO value

2. Fix bug of undifferenced uncombined PPP in troposphere variance setting

3. Output total slant ionosphere delay rather than ionosphere correction

4. Resort broadcast ephemeris and delete dumplicated BDS ephemeris

2019/06/20

1. Change PCO value of BDS GEO satellites when using new antenna file

2. Fix bug in reading RINEX 2 observation file

3. Change ionosphere covariance in single frequency SPP or Graphic PPP

2019/07/05

1. Fix bug of triple-frequency PPP

2019/07/18

1. Fix bug of Kalman Filter in RTK

2. Delete incorrect BDS ephemeris

V1.9

2019/07/28

1. Support DCB estimation

2. Surport barycentric based net solution

3. Fix bug of PPP-RTK(CLAS)

4. Support CLASLIB

2019/10/19

1. Seperate GPS and QZSS in RTK

2. Fix bug of satellite velocity in SSR based PPP

3. Change BDS PCO

4. Fix bug of PPP ambiguity re-initialization in outlier detection

5. Fix bug of cycle slip detection in P1L1 method

6. Fix bug of initial coordinate error in Bancroft

7. Fix bug of ionosphere estimation when only psudo-range observation

2019/11/22

1. Fix bugs of tgd correction in using BDS B1c and B2a signal

2. Fix bug of reading RINEX observation data when clock offset is larger than 0.01 s

3. Fix bug of BDS satellite type classification

4. Change BDS maximum satellite PRN to 38

5. Change QZSS PCO when using gbm products

6. Fix bug of ionosphere output

7. Fix bug of receiving RTCM message

V1.10

2019/12/07

1. Support satellite orbit simulation

2. Surport ublox for PPP-RTK(CLAS) (Tolerance of time difference and support Galileo E5b)

3. Fix bug of figure plotting

2019/12/17

1. Support Galileo E5 signal in PPP-RTK(CLAS)

2. Improve in handing cycle slip and outlier detection

3. Change maximum BDS satellite PRN to 40

2019/12/28

1. Support GBM new product downloading and BDS-3 PPP based on it.

2. Fix bug of BDS-3 satellite data/pilot observation, attitude mode and PCO correction.

3. Fix bug of approximate coordinate estimation.

4. Fix bug in tightly combined RTK

2020/01/03

1. Fix bug of valid period of the Planet ephemeris file

2020/01/11

1. Modify GUI for easier and friendier use.

2. Fix bug of ephemeris matching

3. Add observation data type of GPS

2020/02/03

1. Fix DCB bug of BDS-3 new signals

2. Fix bug of outlier detection in uncombined PPP

3. Support different triple-frequency ionosphere-free PPP

4. Add B1IB2a combination of BDS-3

5. Fix bug in bancroft

6. Fix bug in SSR-based PPP

2020/02/11

1. Fix bug of ocean load correction

2. Add ssr to osr and RINEX in CLAS

3. Change maximum BDS satellite PRN to 46

2020/02/22

1. Fix bugs of DCB corrrection, observation, clock correction, and satellite PRN for BDS3

2. Add option of BDS GEO AR

3. Update the help document

2020/02/26

1. Enable GEO satellite of BDS3

V1.11

2020/03/06

1. Support moving baseline RTK

2. Support FCB from WHU for PPP-AR

3. Fix bug of PPP-RTK(CLAS)

4. Change constraint and walking step of ionosphere parameter in uncombined PPP

5. Fix bug in reading high rate data (>1Hz)

2020/03/10

1. Allow space among observation file name

2. Fix bug when input approximate coordinate is wrong

2020/03/13

1. Support format of SSR file from BNC

2. Support ionosphere-free combination based RTK and PPP_AR

3. Fix bug of L5 frequency-related GPS PPP

V1.12

2020/03/23

1. Support triple-frequency RTK/PPP-AR

2020/04/07

1. Fix bug in reading the time of the first epoch and the antenna file

2. Downweight observation during satellite eclipse period in PPP

3. Automatically change to long baseline RTK mode when baseline length exceeds 30km

4. Fix bug of cycle slip in forward+backward mode

5. Add tropospheric delay model of SHAtropE

2020/04/13

1. Support output of receiver clock

2020/04/21

1. Support installation directory that contains space

2. Fix bugs of GUI

3. Support track plotting with Google Map (API key needed) (Please download from the release tag)

4. Improved partial AR

5. Support post-processed CNES products for PPP-AR

2020/04/25

1. Fix bug of triple-frequency PPP-AR/RTK

2. Fix bug of reading receiver antenna correction

3. Fix bug of forward+backward mode

4. Fix bug of cycle slip for single-frequency data

5. Fix bug bug of triple-frequency PPP of GLONASS

V1.13

2020/07/15

1. Support SSR generation for PPP-RTK (Authorized)

2. Support fast PPP

3. Support PPP-AR for time and frequency transfer (IPPP) (Authorized)

4. Improve wide lane AR

5. Fix bug of IODE matching in SSR based PPP

6. Fix bug of BDS B1c and B2a DCB correction in SSR based PPP

7. Fix bug of approximate coordinate error

8. Add explanation of output files

2020/07/21

1. Add adaptive Kalman Filter in AR

2. Add confidence level based AR

V1.14

2021/08/21

1. Support running Net_Diff via command line

2. Support multi-station PPP

3. Open functions of CLAS

4. Change data downloading using wget, which supports http

5. Improve efficiency of Kalman Filter

6. Fig bug of approximate coordinate calculation

7. Support PPP-AR with bias products from various anlysis centers

8. Support GLONASS RTK with same receiver type

9. More flexible for precise products that containing BDS-3 clock

10. Support precise clock file V3.04

11. Fix some other bugs

2021/09/10

1. Improve outlier detection

2. Fix bug of reading Galileo observation type

3. Fix bug of reading observation header for VRS

V1.15

2022/02/16

1. Support RINEX V4.0

2. Support GLONASS ambiguity resolution without IFB estimation using same receivers

3. Fix bug of outlier detection

4. Fix bug of error correction using ssr data

5. Fix bug of data downloading

2022/04/02

1. Fix bug of reading phase bias files

2. Fix bug of reading RINEX files

2022/04/22

1. Fix bug of reading RINEX 3.05 BDS

2. Support PPP-AR using GFZ integer clocks

3. Add options for BDS PPP-AR

4. Fix bug of download the latest broadcast ephemeris

5. Support online PPP-AR

6. Add option of PCO correction for WL AR

2022/05/02

1. Add minimum satellite number in AR

V1.16

2022/06/21

1. Support GPT3/VMF3

2. Fix bug of reading data type of the third frequency

3. Support PPP for LEO satellites

4. Support reading OBX file

5. Fix bug of IODE for BDS SSR

2022/09/01

1. Fix bug of WL PCO correction for BDS

2. Fix bug of satellite velocity calculation

3. Fix bug of BDS SSR decoding in dumpSSR