RTKLIB

RTKLIB is an open-source GNSS positioning library and toolkit. For LC29H users, the most relevant tool is STRSVR (stream server), which bridges serial GNSS data to NTRIP casters — essential for running an RTK base station.

RTKLIB Tools

Tool	Purpose	LC29H Use Case
STRSVR	Stream server — routes data between serial, TCP, NTRIP, and file	Base station RTCM relay to NTRIP casters
RTKNAVI	Real-time RTK navigation	Alternative to module-internal RTK processing
RTKPOST	Post-processing of RINEX observations	Offline precision analysis
RTKCONV	Raw data to RINEX conversion	Converting log files for post-processing
RTKPLOT	Position and observation plotting	Visualizing track quality and satellite signals

STRSVR for Base Station Operation

STRSVR is the primary tool for relaying RTCM3 corrections from an LC29H(BS) base station module to an NTRIP caster like rtk2go.com.

Data Flow

graph LR
    BS["LC29H(BS)\nModule"] -->|"RTCM3 (serial)"| STRSVR
    STRSVR -->|"RTCM3 (NTRIP)"| Caster["NTRIP Caster"]
    Caster -->|corrections| Rovers

The BS module outputs RTCM3 correction messages on its serial port. STRSVR reads from serial and forwards to an NTRIP caster server, making corrections available to any rover with an NTRIP client.

Configuration

Set Input to Serial, configure the COM port (or /dev/ttyS0, /dev/ttyACM0 on Linux) and baud rate (115200 or 460800)
Set Output to NTRIP Server
Configure the NTRIP caster address, port, mount point, and password
Click Start to begin relaying

STRSVR Input Settings

Parameter	Value
Type	Serial
Port	COM port or `/dev/ttyS0`
Baud Rate	115200 (UART) or 460800 (USB)
Byte Size	8
Parity	None
Stop Bits	1

STRSVR Output Settings (rtk2go.com)

Parameter	Value
Type	NTRIP Server
Address	`rtk2go.com`
Port	`2101`
Mount Point	Your registered mount point name
Password	Your rtk2go password

Linux Usage

On Linux, use str2str (the command-line equivalent of STRSVR):

# Install RTKLIB
sudo apt install rtklib

# Relay serial RTCM3 to NTRIP caster
str2str -in serial://ttyS0:115200 \
        -out ntrips://:password@rtk2go.com:2101/YOUR_MOUNT

The -in and -out flags define stream endpoints:

Stream Type	Format
Serial	`serial://port:baud`
NTRIP Client	`ntrip://user:pass@host:port/mount`
NTRIP Server	`ntrips://:pass@host:port/mount`
TCP Server	`tcpsvr://:port`
TCP Client	`tcpcli://host:port`
File	`file://path`

Multiple Output Streams

STRSVR supports up to 3 simultaneous outputs. Common configurations:

Base station with logging:

str2str -in serial://ttyS0:115200 \
        -out ntrips://:pass@rtk2go.com:2101/MOUNT \
        -out file://rtcm_%Y%m%d%h.log

Base station with local TCP relay:

str2str -in serial://ttyS0:115200 \
        -out ntrips://:pass@rtk2go.com:2101/MOUNT \
        -out tcpsvr://:5015

RTKCONV — Data Conversion

RTKCONV converts raw GNSS observation data to RINEX format for post-processing:

# Convert NMEA log to RINEX observation file
convbin -r nmea input.log -o output.obs

RTKPOST — Post-Processing

For offline RTK computation from RINEX files:

Obtain base station observation data (RINEX .obs)
Obtain rover observation data (from LC29H log)
Convert rover data to RINEX using RTKCONV if needed
Load both files in RTKPOST and process

Post-processing can achieve better accuracy than real-time RTK by using both forward and backward filtering.

RTKPLOT — Visualization

RTKPLOT displays position solutions, satellite observations, and signal quality:

Ground track with fix type coloring (float vs fixed)
Position error time series
Satellite visibility and signal strength
DOP (Dilution of Precision) values over time

On Linux, use the command-line tools or install the Qt-based GUI:

# Plot a position solution file
rtkplot solution.pos

Installation

sudo apt install rtklib

Provides str2str, convbin, rnx2rtkp, and other CLI tools.

git clone https://github.com/tomojitakasu/RTKLIB.git
cd RTKLIB/app/consapp
make