TABLE OF CONTENTS


Introduction

This document explains how to use corrections from Skylark Cx corrections with a u-blox receiver.

The procedure outlined in this document has been tested using a u-blox C099-F9P application board.


For more information about Skylark, please visit the Skylark FAQ.

For more information about the u-blox ZED-F9P and the C099-F9P, please visit the related product pages:


The procedure outlined in this document is also compatible with:


Requirements

  • u-blox receiver
  • Skylark account
  • Windows PC with u-blox u-center installed
  • NTRIP client


Preliminary Setup

Check the firmware version installed on u-blox receiver:

  1. Start u-center
  2. Connect to the appropriate COM port
  3. Navigate to View → Messages View → UBX → MON → VER
  4. Confirm that FWVER ≥ HPG 1.50

Configure CFG-NAVHPG-DGNSSMODE

Make sure the receiver is configured to support Conservative Ambiguity Resolution (CAR):

  1. Start u-center
  2. Connect to the appropriate COM port
  3. Navigate to View→Generation 9 Configuration View→Advanced Configuration
  4. Expand CFG-NAVHPG
  5. Click on CFG-NAVHPG-DGNSSMODE
  6. Change value to 5 - RTK_CAR (Conservative ambiguity resolution)
  7. Click the Set in RAM, Set in BBR and Set in Flash buttons
  8. Click the Send config changes button

Note: for older firmware versions, use the 3 - RTK_FIXED (Ambiguities are fixed whenever possible) configuration option instead.

Connect to Skylark Cx

Option 1: Use u-center NTRIP client

  1. Start u-center
  2. Connect to the appropriate COM port
  3. Navigate to Receiver → NTRIP Client
  4. Configure the NTRIP caster settings section
    • Address: 
      • na.l1l2.skylark.swiftnav.com (North America)
      • eu.l1l2.skylark.swiftnav.com (Europe)
      • ap.l1l2.skylark.swiftnav.com (Asia/Pacific)
    • Port: 2101
    • Username & Password
  5. Click Update source table
  6. Select MSM5 for NTRIP mount point
  7. Press OK
  8. Wait for Fix Mode to change to 3D/DGNSS/FLOAT or 3D/DGNSS/FIXED


Option 2: Provide Skylark Cx correction data via USB, using an external NTRIP client

  1. Identify the USB serial port of your receiver

  2. Start your NTRIP client and configure NTRIP parameters
    1. Address:
      1. na.l1l2.skylark.swiftnav.com (North America)
      2. eu.l1l2.skylark.swiftnav.com (Europe)
      3. ap.l1l2.skylark.swiftnav.com (Japan)
    2. Port: 2101
    3. Username & Password
    4. Mountpoint: MSM5
  3. Select the COM port identified in Step 1 for the output of the corrections (COM8 in this example as shown in Step 1).
    1. Baud Rate: 38400 bps
    2. Byte Size: 8
    3. Parity: None
    4. Stop Bits: 1
    5. Flow Control: None
  4. Verify that the NTRIP client is configured to read the position (NMEA GGA) from this COM port and to send it to Skylark Cx.
    Note: Skylark Cx requests an NMEA GGA sentence to be sent periodically to compute corrections for the receiver's location
  5. Start the NTRIP connection
  6. In u-center, Wait for Fix Mode to change to 3D/DGNSS/FLOAT or 3D/DGNSS/FIXED