What is RTK GPS? A beginner’s guide to Real-Time Kinematic positioning

RTK is a technique used to improve the accuracy of a standalone GNSS receiver. Traditional GNSS receivers, like the one in a smartphone, could only determine the position with 2–4 meters (7–13 feet) accuracy. RTK can give you centimeter accuracy.

A standard GNSS receiver works out where it is by timing how long signals take to arrive from satellites. The atmosphere distorts those signals on the way down, which is why one receiver alone can only get to within a few meters—and why RTK exists.

At a glance:

• Accuracy: 1–2 cm horizontal, 2–4 cm vertical
• Setup: a base receiver + a rover receiver, OR a single rover with an NTRIP subscription
• Best for: land surveying, construction, drone mapping, precision agriculture, machine guidance
• Range: typically 10–30 km between base and rover; longer with multi-band receivers

How does RTK GPS works?

To understand RTK, it helps to start one level up: with GNSS. Global Navigation Satellite Systems (GNSS) is the umbrella term for the constellations of positioning satellites that orbit Earth:

• GPS (United States).
• GLONASS (Russia).
• Galileo (European Union).
• BeiDou (China).
• Plus regional systems like QZSS (Japan) and NavIC (India).

A standard GNSS receiver listens to signals from as many of these satellites as it can see, calculates how long each signal took to arrive, and uses the timing differences to estimate its position.

The result is accurate to within a few meters—useful for navigation, but nowhere near precise enough for surveying or mapping a property line.

RTK, or Real-Time Kinematic, is a positioning method that improves GNSS accuracy from meters down to centimeters. It does this by correcting satellite signal errors in real time.

The base and the rover

An RTK system includes two GNSS receivers: a base and a rover. The base station is set at a known location and constantly receives satellite signals.

It then sends corrections to the rover, which is the moving unit that needs to determine its accurate position. Because both units are observing the same satellites under nearly identical conditions, the rover can use the base’s corrections to eliminate common errors.

This method allows the rover to deliver precise position data with centimeter-level accuracy. RTK GPS technology is especially useful in surveying, mapping, agriculture, construction, and inspection tasks—where real-time precision is critical.

The base station can be a local GNSS unit or a remote reference station accessed via an RTK network. The role of the base remains the same—to provide reference data in real time that allows the rover to calculate its position with much greater accuracy.

These GNSS corrections are what make RTK stand apart from traditional GNSS. While standard GNSS relies only on signal timing, RTK takes advantage of a more detailed technique: carrier phase measurement.

Carrier-phase measurement: why RTK is so precise

Standard GNSS uses code-phase measurements, which align the timing of a coarse digital code in the satellite signal. RTK instead uses the phase of the signal’s carrier wave—the underlying radio wave that carries the code.

The carrier wavelength is around 19 cm, so measuring its phase gives you measurements roughly 100 times more precise than the code alone. The catch is that the receiver has to figure out exactly how many full carrier-wave cycles fit between it and each satellite—a problem called integer ambiguity resolution.

Once it solves that, the position locks in. That moment is what your receiver calls an RTK FIX.

RTK solution states: SINGLE, FLOAT, and FIX

Most RTK receivers display one of three solution statuses while you work. They tell you how much you can trust the position you’re seeing.

• SINGLE: No corrections are being received. Accuracy is similar to standard GNSS—several meters.
• FLOAT: Corrections have begun, but ambiguities aren’t fully resolved. Accuracy improves, but hasn’t yet reached centimeter level.
• FIX: The receiver now delivers centimeter-accurate positions after resolving ambiguities.

Time to first fix can range from a few seconds to a couple of minutes depending on how many satellites are in view, multipath conditions, and how far the rover is from the base.

This video will show you how RTK technology works:

What to expect from RTK accuracy in the field?

On a clear, open site with a strong correction link, you should see the kind of accuracy summarised below. Real numbers will vary with sky visibility, baseline distance, and ionospheric activity.

Method	Typical accuracy	What it’s good for
Standard GNSS (no corrections)	2–5 m	Navigation, smartphone maps
DGPS (code-based corrections)	30 cm – 1 m	Recreational mapping, low-precision GIS
RTK FLOAT	10–50 cm	Sub-meter GIS, asset capture
RTK FIX	1–2 cm horizontal · 2–4 cm vertical	Land surveying, stake-out, drone GCPs, machine control

What can degrade RTK accuracy?

• Long baselines. The further the rover is from the base, the more the atmosphere differs between them. Beyond about 20 km, single-band setups start to struggle; multi-band receivers handle longer baselines well.
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• Poor satellite geometry. If most visible satellites are bunched together in one part of the sky, the position is less reliable. This is reported as DOP (Dilution of Precision).
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• Multipath. Signals bouncing off buildings, vehicles, or wet ground arrive late and confuse the receiver. RTK doesn’t work well in dense urban canyons or under tree canopy.
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• Ionospheric activity. Solar storms can scramble GNSS signals. Most of the time it’s a non-issue, but during severe events FIX times can grow and accuracy can degrade.

A note on absolute accuracy:

RTK gives you a centimeter-accurate position relative to your base. The position’s absolute accuracy—its accuracy in real-world coordinates—depends on how accurately the base itself is known.

If the base is set up over a marker with surveyed coordinates, the rover inherits that accuracy. If the base is averaged over an unknown point, the rover’s positions are still centimeter-accurate to each other but the whole survey can be shifted.

What you need to run RTK: base, rover, and corrections

An RTK setup has three jobs to do: collect satellite signals at a known reference point, collect satellite signals where you actually want to know the position, and move the corrections from one to the other.

1. The base

The base is a GNSS receiver that stays put. Its job is to track the satellites continuously and broadcast correction data. You can either set the base up over a control point with known coordinates, or you can let it average its own position for a few minutes—fine for relative measurements, but you’ll lose absolute accuracy.

If you only ever work in one area, a permanent base on a rooftop or pole is hard to beat. If you move from site to site, a portable base receiver that you set up next to each job works well.

2. The rover

The rover is the receiver you actually carry to the points you want to measure. On a survey pole, mounted on a drone, or fixed to a tractor or excavator.

The rover applies the incoming corrections in real time and tells you whether it’s in SINGLE, FLOAT, or FIX state. Most rovers pair with a controller—a phone, tablet, or dedicated handheld—running the data-collection app.

3.The correction link

Corrections have to get from the base to the rover somehow. There are three common options:

• Radio: Best for on-site setups without internet. It’s reliable when there’s a direct line of sight between the base and the rover.
• NTRIP: A protocol that sends corrections over the internet. Perfect for longer distances or when using a network of reference stations.
• Dual-streaming: Some systems support broadcasting over both radio and internet simultaneously. This ensures corrections stay stable even when one method becomes unreliable.

These flexible delivery methods allow users to choose the right setup for their environment—urban, rural, or remote.

Local base vs. NTRIP and network RTK

There are two ways to source the corrections your rover needs. You can run your own base, or you can subscribe to a service that does it for you. Each has its place, and many surveyors use both depending on the job.

	Your own base	NTRIP / network RTK
Equipment	Two receivers (base + rover) plus a radio link or your own NTRIP setup	One receiver (rover) plus a cellular data plan
Where it works	Anywhere with line of sight between base and rover	Anywhere with cell coverage AND a CORS or commercial network in range
Accuracy	1–2 cm relative to your base; absolute depends on base coordinates	1–2 cm absolute (the network’s bases are surveyed reference stations)
Ongoing cost	None after equipment	Subscription, typically $50–$200 per device per month
Best for	Remote sites, no cell coverage, or large daily surveys	Quick jobs in populated areas; one-person operations

NTRIP (Networked Transport of RTCM via Internet Protocol) is just the standard for delivering RTK corrections over the internet.

Instead of running your own base, you connect your rover to an NTRIP caster, which feeds you corrections from a network of permanently mounted reference stations. National CORS (Continuously Operating Reference Station) networks exist in many countries, sometimes free, sometimes paid.

Commercial networks like Emlid Caster let you stream corrections between your own bases and rovers without standing up your own server.

RTK vs. DGPS, PPP, and PPK

RTK isn’t the only way to get accurate positions out of GNSS. The right choice depends on how accurate you need to be, whether you need the answer in real time, and what your radio or internet situation looks like.

Method	How it works	Typical accuracy	Best for
DGPS	Code-phase corrections from a reference station, real-time	30 cm – 1 m	Recreational mapping, vehicle navigation, low-precision GIS
RTK	Carrier-phase corrections from a base or network, real-time	1–2 cm horizontal	Surveying, stake-out, drone mapping, machine control
PPP	Precise satellite orbit and clock corrections, often via L-band, no local base	10 cm – 1 m, converging over 10–30 minutes	Remote work with no nearby base or NTRIP
PPK	Same carrier-phase math as RTK, but corrections applied after the survey	1–2 cm horizontal	Drone mapping in poor radio/cell conditions, post-processed surveys

RTK vs. PPK in particular

RTK and PPK use the same underlying math. The difference is when the corrections are applied:

• RTK does it in real time, so you see the FIX status in the field and you can stake out points immediately.
• PPK records raw GNSS observations on both the base and the rover and processes them after the survey, on a computer.

Both can hit centimeter accuracy:

• Use RTK when you need to act on positions in real time—placing a stake, guiding a tractor, navigating a drone to a waypoint.
• Use PPK when you don’t need real-time data and you’d rather not depend on a radio or cellular link in the field.

Drone mapping is a common PPK use case because the drone just needs to log raw data and the corrections are applied later in the office. Many modern receivers, including the Reach line, support both.

Where RTK is used?

RTK GPS is now a standard tool across many industries that rely on spatial accuracy:

• Surveying and mapping: From topographic surveys to construction layout.
• Precision agriculture: Automating machinery, planting, and soil analysis with sub-inch accuracy.
• Drone mapping: Enhancing data for orthomosaics and 3D models.
• Construction: Layout tasks, volume measurement, and quality control.
• Inspection and infrastructure: Power lines, roads, pipelines, and more.

Meet the RTK GNSS lineup that makes precision look easy

Need centimeter-level accuracy but don’t want to wrestle with complicated gear, outdated workflows, or fragile equipment? Modern RTK GNSS doesn’t have to feel like a surveying textbook.

Today’s field teams—whether in construction, GIS, engineering, or mapping—need tools that remove friction, not add to it. That means fast setup, reliable all-band RTK performance, and the freedom to move without constantly leveling poles or rechecking points:

Product	What it’s for
Reach RS4 Pro	Our most advanced all-band RTK GNSS receiver, combining centimeter-level positioning with dual cameras, AR stakeout, image-based measurements, and tilt compensation. It’s built for teams who want to move faster on site, capture more in one go, and rethink what a GNSS rover can actually do.
Reach RS4	Delivers powerful all-band RTK performance with tilt compensation in a streamlined setup—perfect for topographic surveys, design set-out, and everyday fieldwork where precision is non-negotiable.
Reach RX2	The ultralight RTK rover made for mobility. With tilt compensation and full RTK capability, it’s ideal for GIS mapping, layout, and terrestrial scanning—high accuracy, zero bulk.

Frequently asked questions