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Emlid Reach RS4 / RS4 Pro RTK Setup: Emlid Flow

Set up the Emlid Reach RS4 and RS4 Pro with RTKdata NTRIP in Emlid Flow. Correction input, GGA, mountpoint AUTO, tilt compensation and fix rate tips.

The Reach RS4 and RS4 Pro are Emlid's current all-band RTK receivers. They track L1, L2, L5 and L6 across 672 channels, carry an IMU for tilt compensation, run up to 16 hours on a charge, and are rated IP68 for use between -40 and +65 degrees C. Both work as base and as rover, and both are configured through the Emlid Flow app on iOS or Android.

For RTKdata the RS4 behaves exactly like the RS3 and the RS2+: corrections arrive over NTRIP through your phone's internet connection, so no local base is set up, levelled or re-surveyed.

Requirements

  • Reach RS4 or RS4 Pro powered on with a clear view of the sky

  • Emlid Flow app on your phone or tablet (iOS or Android)

  • Internet connection on the phone (cellular data or Wi-Fi)

  • RTKdata account with active RTK credentials (username starts with rtk)

  • Survey pole recommended, and required for tilt compensation calibration

Don't have an RTKdata.com account yet? 👉 Start 30-day Free Trial or View Pricing

Step-by-step setup

1

Power on and connect in Emlid Flow

  1. Hold the power button until the LEDs run through their startup sequence.

  2. Open Emlid Flow and select your receiver, or tap + Add new device.

  3. Connect over Wi-Fi (the receiver creates a hotspot named reach:XX:XX) or over Bluetooth if you have paired before.

  4. The device dashboard shows satellite count, solution status and battery level.

If you already use an RS2+ or RS3, nothing here is new. The RS4 appears as a separate device in the list and the correction setup is identical.

2

Open correction input

In Emlid Flow, open the Correction input tab, marked with the satellite dish icon. Select NTRIP and tap + to create a new profile.

3

Enter your RTKdata connection settings

Select the tab for your region:

  • Host (domain): rtk.rtkdata.com

  • Host (IP fallback): 13.56.117.10

  • Port: 2101

  • Username / Password: From RTK Credentials in your account dashboard, not your website login

  • Mountpoint (ALL CAPS): AUTO (recommended), or AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014

  • Host (domain): eu.rtkdata.com

  • Host (IP fallback): 3.73.41.96

  • Port: 2101

  • Username / Password: From RTK Credentials in your account dashboard, not your website login

  • Mountpoint (ALL CAPS): AUTO (recommended), or AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014

  • Host (domain): aus.rtkdata.com

  • Host (IP fallback): 54.206.56.130

  • Port: 2101

  • Username / Password: From RTK Credentials in your account dashboard, not your website login

  • Mountpoint (ALL CAPS): AUTO (recommended), or AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014

Also set:

  • Send receiver position to the correction service: Enabled. This sends NMEA GGA, which is how RTKdata knows where you are and which base station to use. Without it you get no corrections at all.

Tap Save.

AUTO covers the normal case. Pick a specific reference frame only when your project calls for one. The name is case sensitive, so enter it in ALL CAPS. A local coordinate system name is not a mountpoint and leaves you without corrections.

4

Connect and wait for Fix

  1. Tap Connect on the saved profile.

  2. Correction input shows Connected with incoming bytes.

  3. The solution status moves Single, then Float, then Fix.

Under clear sky, expect Fix within 15 to 60 seconds.

5

Calibrate tilt compensation

  1. With an active Fix, mount the receiver on a survey pole.

  2. In Emlid Flow, open Settings > Tilt compensation.

  3. Enable it and follow the on-screen calibration.

  4. Once calibrated, positions stay correct with the pole tilted, and the status bar shows the tilt indicator.

If your fix rate is lower than expected

This is the most common RS4 question we get, and it is almost never the correction stream.

  • Sky obstruction first. Trees, buildings, vehicles and the person holding the pole all block satellites, especially at low elevation. A receiver that sees the whole sky fixes quickly and holds; one working next to a treeline does not.

  • Check the satellite count, not just the status. Below roughly 12 tracked satellites, expect Float rather than Fix.

  • Check the age of corrections in Emlid Flow. Above 5 seconds points at the phone's internet connection, not at the receiver or the network.

  • Distance to the base station matters. Best results within 30 km, workable to about 50 km, unreliable beyond that.

  • Log raw data under the Logging tab. If a site keeps fighting you, PPK on the logged file rescues the survey.

Heights and coordinate systems

RTKdata corrections deliver ellipsoidal heights, not orthometric heights above mean sea level. Use the Global coordinate system for the NTRIP connection, then apply your local datum and geoid in the project settings or in post-processing. See Understanding Heights and Coordinate Systems & Datums.

Troubleshooting

Problem
Cause
Fix

Correction input shows Disconnected

Wrong credentials, or no internet on the phone

Re-enter the username and password from RTK Credentials. The username starts with rtk and is not your website login.

Connected, but the solution stays Single

Position not being sent to the caster

Enable Send receiver position to the correction service. Without GGA the caster cannot assign a base station.

Stuck on Float

Sky obstruction, or the receiver is not upright on a pole

Move into open sky, check the satellite count, and see the fix rate section above.

Mountpoint error

Lowercase or misspelled mountpoint

Type AUTO in ALL CAPS.

"Confirm login to resume data sync"

Emlid cloud sync prompt, unrelated to RTK

Confirm or dismiss it. Corrections keep flowing. If the popup drops the connection, tap Reconnect.

Connection drops repeatedly

Weak cellular signal

Move to better coverage. The receiver reconnects automatically.

Corrections stop when a second device connects

Two devices on one set of credentials

One data stream allows one connection. See Account & Credentials.

Tips

  • Wi-Fi for setup, Bluetooth in the field. Bluetooth keeps the phone's own internet connection free for streaming corrections.

  • Running RS4 Pro as rover next to an RS2+ base is a common setup. If the base pulls its own position from NTRIP at the same time, it needs its own data stream, otherwise the two devices disconnect each other.

  • Battery lasts up to 16 hours, less with tilt compensation and constant streaming. A USB-C power bank covers long days.

  • UHF and LoRa radio are available on the RS4 for local base and rover work. They are an alternative to NTRIP, not a supplement, so use one correction source at a time.

Related Guides

  • Emlid Flow: the app used to configure every Emlid receiver, with correction input and project setup

  • Emlid Reach RS3: previous generation, same NTRIP profile and Emlid Flow workflow

  • Emlid Reach RS2+: widely used mid-range rover, often paired with an RS4 as base

  • NTRIP & GGA Essentials: how the AUTO mountpoint resolves to a base station once your position is sent

  • GNSS Rovers & Receivers: all receiver guides and the universal NTRIP parameters

Related Industry Solutions

PreviousGNSS Rovers and Receivers
NextEmlid Reach RS3

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