There are two modules in rtklib for data processing, namely post-processing analysis rtkpost and real-time processing rtknav.
1, Rtknavi.
The rtknavim module takes the raw observation data as input to perform real-time positioning and navigation. And users can perform RTK-GPS/GNSS positioning under ambiguity OTF (on he fly) calculation by setting the positioning mode to dynamic and inputting receiver data from mobile stations and reference stations.
The main interface is as follows:
Firstly, in the upper left corner of the interface, we can choose the time reference system for positioning and solving, such as UTC, GPST, etc., and the coordinate reference system can be set directly below, such as XYZ geocentric fixed coordinates, ENU northeast sky local coordinate system, etc.
Click on the" button in the upper right corner of the interface; I" The input method, data format, and input data type of the data input stream can be configured.
The optional data types include base station, mobile station data, and correction information.
The optional input types are:
(a) Serial: Input data from a serial port (RS232C or USB).
(b) TCP Client: Connect to a TCP server and input data via the TCP connection.
(c) TCP Server: Accept a TCP client connection and input data via the TCP connection.
(d) NTRIP Client: Connect to a NTRIP caster [20] and input data via the NTRIP.
NRTK (network RTK) server supporting NTRIP and RTCM 2/3 can also be used for the base station via Internet.
(e) File: Input data from a log file.
(f) FTP: Input data after downloading a file by FTP (Only for Correction).
(g) HTTP: Input data after downloading a file by HTTP (Only for Correction).
The supported data formats include:
(a) RTCM2: RTCM 2.3.
(b) RTCM3: RTCM 3.0, 3.1 (with amendment 1-5) and 3.2.
(c) NovAtel OEM6: NovAtel OEM4/V/6 and OEMStar binary format.
(d) NovAtel OEM3: NovAtel OEM3 (Millennium) binary format.
(e) U-Blox: u-Blox LEA-4T, 5T, and 6T binary format.
(f) Superstar II: NovAtel Superstar II binary format.
(g) Hemisphere: Hemisphere Crescent/Eclipse binary format.
(h) SkyTraq: SkyTraq S1315F binary format.
(i) GW10: Furuno GW-10-II/III binary format.
(j) Javad: JAVAD GRIL/GREIS binary format.
(k) NVS BINR: NVS NV08C BINR format.
(l) BINEX: BINEX format (only supports big endian, forward, regular CRC).
(m) SP3: SP3 precision epoch (only for correction).
After selecting the desired input method, we can configure it by clicking on the opt (options) option, such as the serial port number, server address, and so on. And we can enter the interface with the store cmd (commit) option to start and end data input through the command line.
We can configure the output data stream in the same way by clicking "O". Click "L" to configure the log file.
The left half interface is mainly used to display the results of positioning calculation and positioning mode; The right half interface is used to display the signal-to-noise ratio of each frequency point of the satellite system, as well as the number and number of visible satellites. We can select the frequency to be displayed by clicking the down arrow under O, and the satellite map to be displayed by clicking the down arrow under L, including zenith maps of mobile stations and reference stations.
The most important thing is to click on Options to configure the solution mode. This is the key to using RTKLIB for data settlement.
After clicking on Options, we will enter the following interface, which mainly has 7 tabs for different configurations. Below, we will introduce them separately. Readers can also refer to the section 3.5 Configure Positioning Options for RTKNAVI and RTKPOST in the software manual for learning.
1, Setting1.
This tab is mainly used to select:
Positioning Mode: Single point positioning, relative positioning, PPP, static or dynamic;
Frequency of observation data: single frequency, dual frequency, multi frequency;
Filter Type: forward, backward, combination method;
Elevation mask angle;
Signal to Noise Ratio (SNR Mask): The SNR of each frequency point of the mobile station and the reference station can be set separately;
Mobile station mode: If the mobile station is in motion, it will choose to estimate its speed and acceleration;
Earth Tides Correction;
Ionosphere correction methods for ionospheric delay: using IF combination elimination, correcting information correction, parameter estimation, global ionospheric grid model correction, etc;
Troposphere correction for ionospheric delay: parameter estimation or model correction;
Satellite Ephemeris/Clock products used: broadcast ephemeris, precision ephemeris, whether SSR correction information is included;
Satellite and receiver phase center correction (Sat PCV/Rec PCV);
Phase winding of antenna in PPP mode (PhWindup);
Does it include GPS IIA satellite (Reject Ecl);
Is receiver autonomous integrity monitoring (RAIM) enabled;
DCB correction of PPP (DB correct);
Observing satellite constellations and excluding satellite PRN numbers.
2, Setting2.
The relevant configurations that can be performed on this tab include:
The solution method for ambiguity throughout the entire cycle (AR) includes GPS, GLONASS, BDS systems;
The threshold for calculating the ratio of ambiguity detection for the entire cycle;
The confidence level of fixed ambiguity in judgments;
FCB correction of PPP-AR;
Set lock count and cutoff height angle for ambiguity search;
When the signal loses its lock, the value of ambiguity initialization during cycle hopping (Outage to Reset Ambiguity/Slip Thresh);
Max Age of Differential between Mobile Station and Base Station in Differential Mode;
Set the time synchronization mode (Sync Solution);
Set the reject threshold of GDOP and innovation;
The number of iterations for updating the filter;
Baseline Length Constraint;
3, Output.
The output settings for the solution results include:
Format of solution: coordinate system and file format;
Output file header;
Whether to output relevant settings for data processing;
Time format;
Decimal places;
Set latitude and longitude format;
Set the delimiter for the field;
Set the origin of the coordinate system;
Set the format of elevation information;
Set up a geoid model;
Set the output format in static positioning mode: all epochs or starting epochs.
The output interval of NMEA;
The level of settlement results: state estimation and residual level;
Set the level of debugging trace files.
4, Statistics.
This tab is used to configure the statistical characteristics of solution result analysis;
Measurement noise item:
The ratio value of pseudorange and carrier phase error;
Basic deviation of carrier phase;
Set the elevation related term for the standard deviation of carrier phase error;
Set baseline related terms for the standard deviation of carrier phase error;
Doppler frequency;
Process noise item:
Noise caused by receiver acceleration in both horizontal and vertical directions;
The process noise term of carrier phase deviation;
Vertical ionospheric delay;
Zenith ionospheric delay;
Satellite clock stability.
5, Positions.
Set up antenna positions for mobile stations and base stations;
Antenna type: Antenna PCV file;
Set the error of the mobile station antenna relative to the marked antenna reference point;
Input the location file of the measuring station: including the longitude, latitude, elevation, ID, and name information of the measuring station;
6, Files.
Set the path to the data files required for data processing, including:
Satellite and receiver antenna correction information files: atx and. pcv files;
Geoid model;
DCB correction information required for PPP mode;
EOP file: Earth pointing parameters; BLQ format for ocean tides;
The executable file path of Google Earth;
The folder path used to store FTP/HTTP download content.
7, Misc (settings in rtknavi module).
Set the time for data processing loops and the size of the buffer;
Set the time interval for pausing and reconnecting TCP/NTRIP client connections;
Enabling output or log file exchange requires the overlap period between the output file before the second setting and the new output file;
Set the size of the internal settlement buffer and the size of the log file;
Select the navigation information to be used: mobile station, base station, and correction information;
If using SBAS to correct information, it is necessary to input the satellite number of the SBAS satellite used;
Monitor port number;
Set the address and port number of the HTTP/NTRIP proxy server;
Set the font for output;
Specify the NORAD-TLE satellite orbit element data file;
Satellite number: Specify the PRN number of the satellite to be connected.
The Misc tab in the rtkpost module is different from that in rtknavi:
The settings include:
Is the base station observation file interpolated? If yes is selected, the base station data will be linearly interpolated into the mobile station file and a double difference model will be used. If no is selected. Only double difference between adjacent epochs in the base station file;
If you choose to use SBAS's DGPS correction file, you need to input the PRN number of the SBAS satellite you are using;
Develop RINEX reading options for mobile station RINEX data files;
Develop RINEX reading options for the base station RINEX data file;
List of measurement station (mobile station/base station) IDs: For batch processing with multiple input files or sessions, input file paths or output file paths containing specified keywords can be set;
At this point, the relevant configuration for data processing is completed, and clicking start can start data calculation< Br>
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