Swift Navigation Support

Introduction

This article explains how to use Skylark, the Swift Navigation cloud-based GNSS corrections, on the Bad Elf Flex Mini receiver to improve computed position accuracy.

Bad Elf Flex Mini is compatible with Skylark variant:

Skylark Nx RTK

Preparation and Tips

To use Skylark corrections on the Bad Elf Flex Mini, the following is required:

1. Bad Elf Flex Mini receiver.

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

3. Bad Elf Flex 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 Bad Elf Flex Mini with firmware v1.1.3 (1287) and iPhone Bad Elf Flex app v1.4.1 (1408).

Bad Elf Flex Mini Connections

The Skylark corrections are distributed over the Internet using a NTRIP protocol. The Bad Elf Flex app has a built-in NTRIP client software 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 Bad Elf Flex Mini documentation for connection and operation details.

A typical Bad Elf Flex Mini setup to use Skylark corrections is depicted below.

Bad Elf Flex Mini Connections Diagram

Bad Elf Flex Mini Setup Example

Setting Up Flex Mini

1. Install and power up the Flex Mini receiver. Wait until it boots up.

2. Start the Bad Elf Flex app and connect it to the receiver (here named TPR-128) over Bluetooth.

3. By this time the GNSS LED (center) should glow solid green indicating Flex Mini computes the position. GNSS status is also indicated in the app in the GNSS FIX section. It should read 3D or SBAS.

4. Tap SATELLITES menu to check if the Flex Mini has good GNSS signal reception. There should be at least 10 satellites in view with strong (tall bars) GNSS signals.

5. Tap the Back button to return to the main menu.

Using Skylark Corrections

1. Obtain Skylark NTRIP client credentials (if you don't have a Skylark account go to Skylark Sign Up). Bad Elf Flex Mini can work with Skylark Nx RTK corrections on L1/L5 bands.

2. On the Bad Elf Flex app tap CORRECTION MODE menu to select the corrections source

and select RTK via NTRIP option.

3. Tap Network:

and then the [+] button to create a new NTRIP client profile.

4. Enter a profile Name to easily reference the corrections source, e.g. Skylark Nx RTK.

5. Enter the Host for your region per the table below.

Region	Host Address
Europe	eu.l1l5.skylark.swiftnav.com
North America	na.l1l5.skylark.swiftnav.com
Asia / Pacific	ap.l1l5.skylark.swiftnav.com

The "l1l5" in the host address is a lowercase "L1L5". Host address is not case sensitive.

6. Enter Port 2101.

7. Enter the NTRIP User ID and Password as received from Swift.

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

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

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.

10. Tap on the created profile to load it

then tap Connect.

Verifying Corrections Usage

1. Flex Mini 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. The Bad Elf Flex app indicates RTK operation in the GNSS FIX section. With RTK active it'll show RTK (FLOAT) or RTK (FIXED).

3. Tap the GNSS FIX section and observe the Correction age. With good Internet connection, the value should not exceed 2 seconds. Gaps in the corrections stream and a long latency will degrade RTK performance.