Swift Navigation Support

Introduction

This article explains how to use Skylark, the Swift Navigation cloud-based GNSS corrections, on the Emlid Reach RX receiver to improve computed position accuracy.

Emlid Reach RX is compatible with the following Skylark variants:

Skylark Cx

Skylark Nx RTK

Preparation and Tips

To use Skylark corrections on the Emlid Reach RX, the following is required:

1. Emlid Reach RX receiver.

2. Android or iOS smartphone/tablet/mobile device with Internet access.

3. Emlid Flow application (to download refer to the Apple App Store or Google Play).

4. Skylark account (if you don't have an account go to Skylark Sign Up).

5. An open space with a clear view of the sky, with no nearby obstacles like buildings, trees, vehicles or humans, and far away from possible sources of radio interference like computers, other GNSS receivers, radio towers, etc.

The procedure outlined below has been tested using the Emlid Reach RX with firmware v1.8 and iPhone Emlid Flow app v12.

Emlid Reach RX Connections

The Skylark corrections are distributed over the Internet using a NTRIP protocol. The Emlid Flow app has a built-in NTRIP client and the mobile device needs to be connected to the Internet to receive corrections. A reliable Internet connection is required for good navigation performance.

Refer to the Emlid Reach RX documentation for connection and operation details.

A typical Reach RX setup to use Skylark corrections is depicted below.

Emlid Reach RX Connections Diagram

Reach RX Setup Example

Setting Up Reach RX

1. Install and power up the Reach RX receiver, and wait till it boots up (Status LED glows solid white).

2. Start the Emlid Flow app and connect it to the receiver (here named TPR-71) over the Bluetooth.

2. Tap Status menu to check if the Reach RX has good GNSS signal reception.

There should be at least 10 satellites in view, strong GNSS signals should reach a level of around 45 dB-Hz, and the receiver should have a valid SINGLE solution.

Using Skylark Corrections

1. Obtain Skylark NTRIP client credentials (if you don't have a Skylark account go to Skylark Sign Up) and choose the corrections variant. Reach RX can work with Skylark Cx and Skylark Nx RTK corrections on L1/L2 bands.

2. On the Emlid Flow app navigate to NTRIP Profile (menu Profile -> My NTRIP Profiles) and tap Add profile button.

3. Enter Profile name to easily reference the corrections source, e.g. Skylark Nx RTK

4. Enter the Address for your region per the table below.

Region	Address
Europe	eu.l1l2.skylark.swiftnav.com
North America	na.l1l2.skylark.swiftnav.com
Asia / Pacific	ap.l1l2.skylark.swiftnav.com

The "l1l2" in the address is a lowercase "L1L2". Address is not case sensitive.

5. Enter Port 2101.

6. Enter the NTRIP Username and Password as received from Swift.

7. Keep the Send receiver's position to the provider NMEA GGA enabled. Reach RX needs to send its approximate location to Skylark periodically to receive appropriate corrections for your location.

8. Tap Mount point and select desired Skylark corrections stream from the displayed list. Examples of commonly used mountpoints:

Mount point	Skylark Stream
MSM5	Skylark Cx with ITRF2020 reference frame
NXRTK-MSM5	Skylark Nx RTK with ITRF2020 reference frame
NXRTK-NAD83-MSM5	Skylark Nx RTK with NAD83 reference frame (US only)

Note: Skylark Cx creates a virtual reference station (base) 100 km towards the equator from the device's location. This is an intended behavior and such a long baseline does not degrade performance.

Refer to the NTRIP Client Configuration for Skylark Corrections for a full list of available mountpoints, including regional reference frames (datums).

9. Tap the Save button.

Verifying Corrections Usage

1. Reach RX should start receiving corrections shortly (within a few seconds) after enabling NTRIP. Receiving corrections is indicated in the app.

2. Shortly after receiving corrections, the receiver should start using them to improve computed position accuracy. RTK operation is indicated by a yellow (RTK Float) or green (RTK Fixed) LED indicator.

The Emlid Flow app indicates RTK operation in the top status bar (FLOAT/FIX) and the Solution field on the Status page.

3. Observe the Age of corrections in the status page. With good Internet connection, the value should not exceed 2 seconds. Gaps in the corrections stream and a long latency will degrade RTK performance.