This document explains how to use corrections from Skylark Cx corrections with a Septentrio GNSS receiver.

The procedure outlined in this document has been tested using a mosaic-go GNSS module receiver evaluation kit.

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

For more information about the Septentrio mosaic-X5 receiver and the mosaic-go GNSS module receiver evaluation kit, please visit the related product pages:

The procedure outlined in this document is compatible with other mosaic modules as well as with other Septentrio products (e.g. AsteRx product family):


  • Septentrio mosaic-go evaluation kit
  • Skylark account
  • Windows PC with Septentrio RxTools suite installed
  • optional external NTRIP client
  • optional PC sharing its internet access to the mosaic-go module's web interface via the USB connection

Preliminary Setup

Check the firmware version installed on the Septentrio receiver

  1. Open RxControl 
  2. In menu File  Change Connection connect to the appropriate COM port
  3. In menu Tools   Expert Console    tab ASCII in the last line check the firmware version
  4. Confirm that FW is v4.12.1 or higher

Configure RTK Rover

Make sure the receiver is configured to support RTK Fixed and RTK Float

  1. In RxControl menu Navigation   Positioning Mode →  PVT Mode: enable RTKFloat + RTKFix 

Connect to Skylark Cx

Connect a USB or serial cable from the Septentrio Receiver to the PC or tablet. The NTRIP connection for differential corrections can be configured in the DataLink Tool

  1. Start DataLink
  2. In Connection 1, select Connection Mode Serial and set Serial Port settings to the Port 2 with its configuration.

  3. In Connection 2, configure the NTRIP Caster settings
    • Host: 
      • (North America)
      • (Europe)
      • (Asia/Pacific)
    • Port: 2101
    • Enable Authentication with User & Password
      Click Stream Details
  4. Select MSM5 for NTRIP mount point (Stream)

  5. Press OK
  6. In Connection 1,connect GGA to Connection 2, send every 1'th received GGA and click Connect
    In Connection 2 connect Link to Connection 1, send every 1'th received GGA and click Connect

  7. In RxControls, Communication  Input/Output Selection   Input USB2 set RTCM3
    In RxControls, Communication   Input/Output Selection   Output USB2 set NMEA:

    In RxControls, Communication →  Output Settings →  NMEA Output in USB2 set GGA

    In RxControls, Communication →  Output Settings →  Interval for Stream 5/USB2 set 1 sec

  8. Check in the Receiver Status PVT tab the RTK mode for RTK Float or RTK Fixed.

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

  1. Identify the USB serial port of your receiver, e.g. Port 2

  2. Start your NTRIP client and configure NTRIP parameters
    1. Address:
      1. (North America)
      2. (Europe)
      3. (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: 115200 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 RxControls, wait for PVT Fix Mode to change to RTK Float or RTK Fixed