Swift Navigation Support

Introduction

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

Duro is compatible with Skylark variants:

Skylark Cx

Skylark Nx RTK

Preparation and Tips

To use Skylark corrections on Duro the following is required:

1. Duro or Duro Inertial receiver with firmware version 2.4.21 or newer (refer to Appendix A for the firmware version checking procedure).

2. L1/L2 GNSS antenna in an open sky location (refer also to GNSS Antenna Placement Guidelines).

3. Ethernet router/switch with Internet access (refer also to Cell Modems and Network Routers).

4. Windows, macOS or Linux computer connected to Duro over a serial port or Ethernet network.

5. Swift Console program (to download installer and manual refer to Swift Console page).

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

Several receiver settings may affect operation with corrections and therefore it's strongly recommended to start with the Duro having factory default settings. Refer to Appendix B for resetting Duro to factory defaults procedure.

The procedure outlined below has been tested using Duro with firmware v3.0.17 and Swift Console v4.0.19.

Duro Connections

The Skylark corrections are distributed over Internet using NTRIP protocol. Duro has a built-in NTRIP client software and needs to be connected to the Internet over an Ethernet port to receive corrections. A reliable Internet connection is required for good navigation performance.

Duro can be controlled and monitored over the Ethernet or serial port. Refer to the Duro User Manual for connection and operation details.

A typical Duro setup to use Skylark corrections is depicted below.

Duro Connections Diagram

At a minimum Duro requires the following connections:

1. Power

2. L1/L2 GNSS antenna

3. Ethernet port to receive corrections from Internet and for control

Notes:

1. Alternatively, an AUX serial (RS232) port can be used for Duro control. If necessary, use an RS232 to USB adapter to connect the AUX port to your computer.

2. It's also possible to connect Duro over an Ethernet port to the computer directly (using a static IP addresses on both Duro and the computer) and share Internet access from the computer, but such a connection is often not reliable and will always require a computer to be present in the system. Using a separate cell modem / router is recommended.

Duro Connections Example

(1) Mini-survey L1/L2 GNSS antenna (GPS500)

(2) Duro receiver

(3) Cell modem USB dongle with Ethernet router (MOFI4500)

(4) Control computer

Configuring Duro

1. Start the Swift Console program and connect to Duro.

2. Ensure Duro has firmware version v2.4.21 or newer. Refer to Appendix A for firmware version checking procedure.

3. On the TRACKING tab ensure Duro receives good GNSS signals on both L1 and L2 bands (strong signals should be above 45 dB-Hz), and has a valid live fix (Position field in the status bar shows SPP or SBAS mode).

4. Ensure Duro has Internet access - the LINK LED on Duro's front panel should be lit red.

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. Duro can work with Skylark Cx and Skylark Nx RTK corrections.

2. Open the Swift Console SETTINGS tab and navigate to the ntrip section.

Note: the NTRIP settings can be changed only if the enable field is False.

3. Enter the NTRIP username and password as received from Swift.

4. Enter the NTRIP url for your region and chosen corrections variant per the table below.

Region	Skylark Variant	URL
Europe	Cx	eu.l1l2.skylark.swiftnav.com:2101/OSR
Europe	Nx RTK	eu.l1l2.skylark.swiftnav.com:2101/NXRTK-MSM5
North America	Cx	na.l1l2.skylark.swiftnav.com:2101/OSR
North America	Nx RTK	na.l1l2.skylark.swiftnav.com:2101/NXRTK-MSM5
Asia / Pacific	Cx	ap.l1l2.skylark.swiftnav.com:2101/OSR
Asia / Pacific	Nx RTK	ap.l1l2.skylark.swiftnav.com:2101/NXRTK-MSM5

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

5. Keep the gga out interval at 10 seconds. Duro needs to send it's approximate location to Skylark periodically to receive appropriate corrections for Duro location.

6. Set the NTRIP enable field to True.

7. Click the SAVE TO DEVICE button to retain settings over the power cycle or a device reset.

Verifying Corrections Usage

1. Duro should start receiving corrections shortly (within a few seconds) after enabling NTRIP.

2. Receiving corrections is indicated by a blinking LINK LED (red) on Duro's front panel.

3. Shortly after receiving corrections, the receiver should start using them to improve computed position accuracy. RTK operation is indicated by a blinking (RTK Float) or solid (RTK Fixed) MODE LED (blue).

The Swift Console indicates RTK operation in the status bar.

When corrections are used, Position reads RTK and the RTK mode shows either Float or Fixed.

4. Observe the Corrections Age in the status bar. With good Internet access, the value should not exceed 2 seconds. Gaps in the corrections stream and a long latency will degrade RTK performance.

5. Additionally, if more details are required, the Swift Console shows incoming corrections data on the OBSERVATIONS tab in the Remote section

and computed RTK baseline details are shown on the BASELINE tab.

6. When corrections are used, Duro output will contain highly accurate latitude, longitude and altitude positions in standard SBP and NMEA messages. Refer to the protocol specification for message details.

Appendix A - Checking Firmware Version

To check the Duro firmware version follow the procedure below:

1. Start the Swift Console program and connect to Duro over Ethernet or an AUX serial port. Upon connection, Swift Console will retrieve all of Duro's settings.

2. Open the UPDATE tab.

3. The Duro firmware version will be shown in the Current field.