RTK High-Precision GNSS Positioning Technology: A Complete Guide from System Principles and Deployment to Accuracy Testing

1. What Is RTK High-Precision Positioning?

Traditional GPS, BeiDou, and GNSS positioning devices can usually achieve meter-level positioning accuracy. In open environments, typical positioning accuracy is approximately 2 to 10 meters.

For ordinary vehicle tracking, personnel trajectory recording, livestock tracking, and asset monitoring, this level of accuracy is generally sufficient for basic applications.

However, for industrial personnel positioning, surveying, unmanned equipment, precision agriculture, construction machinery, robotics, boundary detection, and high-precision trajectory analysis, meter-level errors may be far from sufficient.

This is where RTK high-precision positioning technology becomes necessary.

RTK stands for:

Real-Time Kinematic

It is commonly referred to as:

Real-Time Kinematic Differential Positioning Technology

RTK is not simply achieved by replacing a conventional GPS module with a more advanced module. Instead, it works on top of GNSS satellite positioning by using a reference base station or a network correction service to provide real-time correction data.

These corrections help the mobile terminal eliminate a large portion of satellite positioning errors, improving positioning accuracy from the traditional meter level to the centimeter level.

Under favorable satellite conditions and with proper deployment, an RTK system can typically achieve:

• Horizontal positioning accuracy: approximately 1–3 cm
• Vertical positioning accuracy: approximately 2–5 cm
• Real-time positioning output: 1 Hz, 5 Hz, 10 Hz, or even higher
• Static positioning
• Dynamic positioning
• Real-time trajectory recording
• Centimeter-level movement detection

RTK is therefore particularly suitable for applications that need to determine questions such as:

• Where exactly is a worker standing?
• Has a vehicle entered a specified lane?
• How many centimeters has a device moved?
• Has livestock crossed a precisely defined boundary?

2. Why Can RTK Achieve Centimeter-Level Accuracy?

A conventional GNSS receiver calculates its current position by receiving signals from satellite systems such as GPS, BeiDou, GLONASS, and Galileo.

However, satellite signals traveling from space to the ground are affected by many sources of error, including:

• Satellite orbit errors
• Satellite clock errors
• Ionospheric delays
• Tropospheric delays
• Multipath reflections
• Receiver noise
• Antenna installation conditions
• Building obstruction
• Tree obstruction
• Electromagnetic interference

After these errors accumulate, conventional GNSS has difficulty maintaining centimeter-level accuracy over long periods.

The core concept of RTK is to introduce a reference point with a known position.

This reference point is called:

RTK Base Station

Another device that is moving or needs to determine its position is called:

Rover

The base station knows its exact coordinates and continuously receives satellite signals.

Because the true coordinates of the base station are already known, the system can determine:

“How much error exists between the satellite-calculated position and the actual position?”

The base station then sends this correction information to the rover in real time.

After receiving the differential correction data, the rover combines it with its own satellite observations and performs carrier-phase calculations, significantly reducing common positioning errors.

This ultimately enables centimeter-level positioning.

A simple way to understand it is:

Conventional GPS: The device calculates its position by itself.

RTK: The device calculates its position and uses a known reference coordinate for real-time correction.

3. What Components Make Up a Complete RTK System?

A complete RTK system usually consists of several major components.

1. GNSS Satellite Systems

Modern RTK devices typically support multiple constellations and multiple frequency bands rather than relying only on GPS.

Common satellite systems include:

• GPS
• BeiDou BDS
• Galileo
• GLONASS
• QZSS

The advantage of multi-constellation GNSS is that the device can observe more satellites at the same time.

A higher satellite count generally helps to:

• Improve positioning speed
• Improve availability in complex environments
• Reduce the effects of obstruction
• Increase the probability of achieving RTK FIX
• Improve positioning stability

2. RTK Base Station

The base station should be installed at a fixed location with known coordinates and good satellite visibility.

Its main functions include:

• Receiving GNSS satellite data
• Calculating positioning errors
• Generating RTCM correction data
• Sending correction data to mobile terminals

The base station can transmit data through multiple methods, including:

• 4G
• Ethernet
• Wi-Fi
• LoRa
• UHF
• NTRIP network
• Private TCP/UDP server

3. RTK Rover Terminal

The mobile terminal is also known as the Rover.

Typical examples include:

• RTK personnel tracking badge
• RTK GNSS personnel tracker
• RTK vehicle terminal
• RTK livestock collar
• RTK asset tracker
• RTK construction machinery tracking device
• RTK robot positioning terminal

A typical terminal may include:

GNSS RTK module, MCU, communication module, battery, power management circuit, GNSS antenna, network antenna, and various sensors.

4. Differential Data Communication Network

RTK requires real-time correction data.

Therefore, the communication link is extremely important.

Common approaches include:

4G + NTRIP

The device connects to the internet through 4G and logs into an NTRIP server to obtain RTCM correction data.

Suitable applications include:

• Urban personnel positioning
• Nationwide deployment
• Vehicle positioning
• Engineering equipment
• Distributed devices

LoRa / LoRaWAN

Within a local area, LoRa can be used to transmit RTK-related data or auxiliary communication data.

Suitable environments include:

• Large farms
• Industrial parks
• Mining areas
• Ports
• Private campuses
• Areas without stable public network coverage

UHF

Traditional surveying RTK systems frequently use UHF radios.

The advantage is that they do not depend on a mobile operator network.

However, communication distance, antenna conditions, and local radio regulations must all be considered.

4. What Is RTCM?

One important term frequently encountered in RTK systems is:

RTCM

RTCM can be understood as a standardized differential correction data format used in RTK systems.

A base station or NTRIP correction provider continuously transmits RTCM messages.

After the RTK GNSS module receives RTCM data, it can perform differential positioning calculations.

Typical RTCM messages may contain:

• Base station coordinates
• GPS observation data
• BeiDou observation data
• Galileo observation data
• GLONASS observation data
• Multi-constellation correction information

Therefore, when developing an RTK device, it is not enough to confirm that the GNSS module supports RTK.

You must also verify:

Whether RTCM data is actually being delivered to the GNSS module.

Many RTK debugging failures are not caused by satellite positioning problems.

Instead, they occur because the RTCM correction data link has not been successfully established.

5. Common RTK Positioning States

When testing an RTK device, you should not look only at latitude and longitude.

The most important information is the current solution status.

Typical positioning states include:

1. Single

Single-point positioning.

This means the device is essentially operating as a conventional GNSS receiver.

Accuracy is usually still at the meter level.

2. DGPS / DGNSS

The device has already received a certain level of differential correction.

The accuracy may be better than single-point positioning, but it usually has not yet reached centimeter-level accuracy.

3. RTK Float

This is known as:

RTK Float Solution

It indicates that the device has started carrier-phase differential calculations, but the integer ambiguity has not yet been completely resolved.

Accuracy in this state may range from:

Several tens of centimeters to sub-meter level.

However, this state should not be treated as stable centimeter-level RTK for project acceptance.

4. RTK Fixed

This is known as:

RTK Fixed Solution

This is the most important state for an RTK device.

Once the device enters RTK FIX, it can typically provide stable centimeter-level positioning.

Therefore, during actual project testing, it is not enough to say:

“The device is connected to RTK.”

Instead, you should confirm:

Whether the device can remain in RTK FIX for extended periods.

6. What Should Be Prepared Before RTK Deployment?

Before installation, the following equipment and information should be prepared.

RTK Hardware

Including:

• RTK GNSS terminal
• GNSS antenna
• 4G or LoRa communication module
• RTK base station or NTRIP service
• Power supply
• Data server
• Test computer

Software Tools

Recommended tools include:

• Serial port debugging software
• GNSS debugging tools
• NTRIP Client
• TCP/UDP debugging tools
• Mapping platform
• RTK status monitoring page
• Logging software

Test Parameters

Confirm the following in advance:

• GNSS module model
• Supported frequency bands
• Supported satellite constellations
• Whether RTCM input is supported
• Whether NMEA output is supported
• RTK output frequency
• Source of correction data
• NTRIP account
• Mountpoint
• IP address
• Port
• APN
• SIM card network

7. How Should an RTK Base Station Be Installed?

Base station installation quality has a major impact on RTK project performance.

An incorrectly installed base station can directly affect the accuracy of all RTK devices in the covered area.

1. Select an Open Location

The GNSS antenna should have as clear a view of the sky as possible.

Avoid installing it near:

• Tall buildings
• Large metal roofs
• High-voltage power lines
• Large trees
• Dense tower structures
• Glass curtain walls
• Heavy machinery

The GNSS antenna should ideally have a wide and unobstructed view of the sky.

2. The Antenna Must Be Fixed

Once the base station antenna is installed, it should not be moved casually.

The base station coordinates serve as the reference coordinates for the entire RTK system.

For example, if the base station antenna is moved by 20 cm, the absolute coordinates of many rover terminals in the area may shift by a corresponding amount.

The base station should therefore be installed on:

• A fixed mounting bracket
• Building rooftop
• Concrete foundation
• Dedicated survey point
• Long-term stable structure

3. Waterproofing and Lightning Protection

For outdoor deployment, additional measures should include:

• IP65/IP67 waterproofing
• Lightning protection
• Grounding
• Surge protection
• Waterproof connectors
• UV-resistant cables
• Secure antenna mounting

8. How Should an RTK Rover Device Be Installed?

For personnel RTK badges or portable RTK terminals, the GNSS antenna position directly affects final positioning performance.

Personnel Devices

Recommended wearing positions include:

• Shoulder
• Top of helmet
• Upper chest
• Top of backpack

Compared with placing the device inside a trouser pocket, higher mounting positions usually provide a better view of the sky.

Vehicle Devices

The GNSS antenna should preferably be installed on:

• Vehicle roof
• Cab roof
• A location without metal obstruction

Do not completely enclose the GNSS antenna inside a metal housing.

Construction Machinery

Keep the GNSS antenna away from:

• Electric motors
• High-power DC/DC converters
• High-frequency switching power supplies
• Inverters
• Communication antennas

This helps reduce EMC interference that may affect GNSS reception.

9. How Is a 4G Network RTK System Configured?

If NTRIP network RTK is used, the general process is as follows.

Step 1: Obtain Normal GNSS Positioning

First confirm that the GNSS module can normally output:

• Longitude
• Latitude
• Altitude
• Satellite count
• UTC time

If conventional GNSS positioning is already unstable, RTK debugging should not begin yet.

Step 2: Connect the Device to the 4G Network

Check:

• SIM card
• APN
• IP
• DNS
• Network registration
• TCP connection

Make sure the device can communicate with the server properly.

Step 3: Connect to the NTRIP Server

Typical parameters include:

NTRIP Server: server address

Port: server port

Username: account username

Password: account password

Mountpoint: correction stream mountpoint

Step 4: Upload the Device's Approximate Position

Some NTRIP services require the rover to upload GGA data.

GGA may include:

• Latitude and longitude
• Altitude
• Satellite count
• Positioning status

The NTRIP server can then select appropriate correction data according to the device location.

Step 5: Receive RTCM Data

After the connection is established successfully, the device should continuously receive RTCM binary data.

It is recommended to monitor:

RTCM Received Bytes

If the value remains at zero, the correction data link is not working properly.

Step 6: Send RTCM Data to the GNSS Module

The MCU must forward the received RTCM data to the GNSS RTK module through UART, USB, or another interface.

This step is also one of the most common failure points during RTK device development.

10. How Should the First RTK Test Be Performed?

For the first RTK test, do not start in a dense urban environment or around large groups of people.

Choose an open location such as:

An open parking lot, sports field, rooftop, or open farmland.

The test procedure can be performed as follows.

Step 1: Cold Start the GNSS Device

Power off the device completely.

Restart it.

Record:

TTFF

which means:

Time To First Fix

Step 2: Record Normal GNSS Status

Record:

• Total satellite count
• GPS satellite count
• BeiDou satellite count
• Galileo satellite count
• HDOP
• Latitude and longitude
• Positioning status

Step 3: Connect RTK Correction Data

Enable 4G or another correction data communication link.

Confirm:

RTCM Received > 0

Step 4: Observe RTK State Changes

Under normal conditions, the state may transition as follows:

Single

↓

DGNSS

↓

RTK Float

↓

RTK Fixed

Record:

Time to RTK Fix

This represents the total time from startup until the device enters RTK FIX.

11. How Should RTK Static Accuracy Be Tested?

This is a very important test.

Fix the RTK device at one location.

For example, keep it stationary for 30 minutes.

Record the position every second.

Suppose the device is completely stationary, but the coordinates still change slightly:

22.5432161

22.5432163

22.5432160

This small variation is normal measurement noise.

You should analyze:

• Maximum deviation
• Average deviation
• CEP
• RMS
• Horizontal error
• Vertical error

If the device remains fixed in place while staying in RTK FIX, but the trajectory jumps several meters or even tens of meters on the map, then the system still has a problem.

12. How Should RTK Dynamic Accuracy Be Tested?

After the static test passes, perform a dynamic positioning test.

A fixed test route can be designed.

For example:

A → B → C → D

The real coordinates of each test point should be measured in advance.

A person or vehicle carrying the RTK device then travels through these points.

Test the following:

• Whether the trajectory is stable
• Whether the track is continuous
• Whether drift occurs
• Whether sudden position jumps occur
• Whether RTK FIX is interrupted
• How long it takes to recover FIX after passing through an obstructed area

13. Repeatability Testing

One important indicator of a high-precision positioning system is:

Repeatability

For example, mark a test point on the ground.

The test operator leaves the point and then returns to it.

Repeat this:

20 times, 50 times, or even 100 times.

Record the system coordinates each time.

Observe whether all recorded points remain concentrated within a very small area.

If the system repeatedly identifies almost the same coordinates each time the operator returns to the same physical point, then the system has good repeat positioning performance.

14. RTK Obstruction Testing

Real-world projects will not always operate in completely open environments.

Therefore, testing should also be performed near:

• Buildings
• Trees
• Vehicles
• Steel structures
• Roof overhangs

The key transitions to observe are:

RTK Fixed → Float

and:

Float → Fixed

Measure how long each transition takes.

This parameter is extremely important in real industrial applications.

15. Base Station Distance Testing

If a local RTK base station is used, different baseline distances should be tested.

For example:

1 km

5 km

10 km

20 km

30 km

Observe:

• RTK FIX acquisition speed
• Horizontal accuracy
• Vertical accuracy
• FIX stability rate

As the distance between the base station and rover increases, the correlation of atmospheric errors between the two locations decreases.

Therefore, RTK performance generally decreases gradually as the baseline distance becomes longer.

16. Special Challenges of RTK Personnel Positioning

When RTK is used for personnel positioning, there is one very practical problem:

The human body itself can block GNSS signals.

If the badge is worn on the chest, body movement and rotation may block part of the sky.

Therefore, RTK personnel product design must pay special attention to:

• GNSS antenna position
• Antenna dimensions
• Antenna gain
• Antenna orientation
• Enclosure materials
• Human body influence
• Isolation between 4G antenna and GNSS antenna

Industrial products should not be evaluated only by laboratory RTK module specifications.

They must be tested under:

Complete device + enclosure + battery + real human wearing conditions

17. What Is the Relationship Between RTK and Indoor Positioning?

It is important to clarify that:

RTK GNSS is mainly suitable for outdoor or semi-open environments.

GNSS satellite signals have difficulty penetrating large buildings.

Therefore, true indoor centimeter-level positioning generally requires technologies such as:

• UWB
• Bluetooth AoA
• Visual positioning
• SLAM
• IMU fusion
• BLE Beacon

For a large industrial campus, a more practical system usually does not rely on RTK alone.

A better architecture may be:

Outdoor: RTK GNSS

Semi-open areas: GNSS + IMU

General indoor areas: Bluetooth

High-precision indoor areas: UWB

All location data can then be managed through the same personnel positioning platform.

This approach is generally more reliable than attempting to use RTK for all indoor and outdoor environments.

18. RTK + 4G Personnel Tracking System Architecture

For example, a high-precision personnel RTK system can use the following architecture:

RTK GNSS personnel badge

↓

4G network

↓

NTRIP correction service

↓

RTCM correction data

↓

RTK GNSS module

↓

Centimeter-level coordinates

↓

4G upload to server

↓

Personnel tracking platform

The platform can then support functions such as:

• Real-time personnel location
• Historical trajectory
• Geofencing
• SOS alarm
• Boundary crossing alarm
• No-motion alarm
• Fall detection
• Attendance management
• Regional personnel counting
• API integration
• Web management
• Android APP
• iOS APP

19. How Can RTK Be Combined with LoRaWAN?

For large farms, mines, industrial parks, and similar environments, a hybrid architecture can also be designed using:

RTK GNSS + LoRaWAN + 4G

For example:

RTK GNSS positioning

↓

LoRaWAN position data transmission

↓

LoRaWAN Gateway

↓

4G / Ethernet

↓

Server

This approach can reduce the need for an individual SIM card in every terminal.

If public network access is still required for differential correction data, the system architecture can additionally include:

• 4G backhaul
• Local RTK base station
• Private differential correction server

20. Common Problems During RTK Device Development

1. Device Always Remains in Single Mode

Check:

Whether RTCM data is actually being received.

2. Device Always Remains in Float Mode

Check:

• Satellite count
• Dual-frequency GNSS signals
• Antenna performance
• Base station distance
• RTCM message types
• Multipath environment

3. RTK FIX Drops Back to Float

Common causes include:

• Signal obstruction
• Multipath interference
• Correction data interruption
• 4G network instability
• Poor antenna design

4. RTK FIX Is Achieved but Coordinates Are Still Incorrect

This situation deserves particular attention.

Possible causes include:

• Incorrect base station coordinates
• Incorrect coordinate system
• Incorrect height reference system
• Antenna phase center error
• Base station position has been moved

5. The Device Works in the Laboratory but Performs Poorly After Final Assembly

Typical areas to inspect include:

• GNSS antenna matching
• LNA
• PCB layout
• 4G interference
• DC/DC interference
• MCU clock interference
• RF shielding
• Power supply noise

21. What Data Should Be Recorded During RTK Testing?

It is recommended that the backend platform store complete GNSS diagnostic information rather than recording only latitude and longitude.

At minimum, the following fields should be stored:

Timestamp

Latitude

Longitude

Altitude

Fix Type

RTK Status

Satellite Count

HDOP

RTCM Age

RTCM Received Bytes

Speed

Heading

4G Signal

Battery

This makes it much easier to analyze abnormal behavior when problems occur.

22. How Should an RTK Project Be Finally Accepted?

A professional RTK project should not be accepted based only on a single statement such as:

“Accuracy is 2 cm.”

Multiple performance indicators should be defined.

For example:

Horizontal Accuracy

Under RTK FIX:

≤ 2–3 cm

Vertical Accuracy

≤ 5 cm

RTK FIX Time

A target value should be defined according to the actual system.

FIX Availability Rate

Measure the percentage of valid test time during which the device remains in RTK FIX.

Static Drift

Measure coordinate variation while the device is completely stationary.

Dynamic Trajectory Error

Measure deviation between the actual route and the recorded RTK trajectory.

Obstruction Recovery Time

Measure how long it takes the device to return to RTK FIX after satellite obstruction.

Network Recovery Capability

Manually disconnect the 4G network and then restore it.

Check whether:

• NTRIP reconnects automatically
• RTCM transmission resumes automatically
• RTK FIX recovers automatically

23. What Applications Are Suitable for RTK Technology?

RTK is no longer limited to traditional land surveying.

It can now be applied to many different applications.

High-Precision Personnel Positioning

Suitable for:

• Large industrial parks
• Mining sites
• Ports
• Construction sites
• High-risk operating areas

Precision Agriculture

Used for:

• Agricultural machinery guidance
• Autonomous driving
• Route control

Livestock Management

It can be used for:

• High-precision livestock positioning
• Grazing trajectory tracking
• Boundary management
• Virtual fencing research

Construction Machinery

Suitable for:

• Excavators
• Bulldozers
• Road rollers
• Construction vehicles

Robots and Unmanned Equipment

RTK can be integrated with:

• IMU
• Vision
• LiDAR

to build sensor-fusion positioning systems.

High-Precision Asset Location Management

In large outdoor yards, ports, terminals, and storage areas, RTK can significantly improve asset location accuracy.

24. Future Development of RTK High-Precision Positioning Systems

Future RTK devices will not simply be independent GNSS modules.

More practical products will increasingly use multi-sensor fusion.

For example:

RTK + GNSS + IMU + 4G + LoRaWAN + Bluetooth

Different technologies can solve positioning problems in different environments.

In open outdoor environments:

RTK provides centimeter-level absolute positioning.

During short periods of satellite obstruction:

IMU provides inertial compensation.

Indoors:

Bluetooth or UWB continues to provide location information.

For long-distance communications:

4G or LoRaWAN uploads position data to the server.

The final system can therefore provide:

Indoor + Outdoor + High Precision + Long-Range Communication + Cloud Platform

as an integrated positioning solution.

Conclusion

The true value of RTK is not simply improving GPS accuracy from several meters to several centimeters.

A complete RTK system actually includes:

GNSS satellite reception + RTK algorithms + differential base station + RTCM data + communication network + antenna design + device hardware + cloud platform + installation engineering + accuracy testing

A problem in any one of these areas may affect the final centimeter-level positioning result.

Therefore, when designing an RTK personnel badge, RTK asset tracker, RTK vehicle terminal, or RTK industrial positioning device, it is not enough to focus only on the GNSS module specification claiming “centimeter-level accuracy.”

What must actually be verified is:

Can the device quickly achieve RTK FIX in a real installation environment? How long can it maintain FIX? How quickly does it recover after obstruction? Is the dynamic trajectory stable? Can the complete device operate reliably over the long term?

Only after validating the complete system—from hardware design and antenna design to differential data communication, equipment installation, and field testing—can a truly practical RTK high-precision positioning system be built for real industrial applications.

Technical article shared from: https://wechatgps.net