Using Net DGPS to forward NTRIP corrections

Using Net DGPS to forward NTRIP corrections to an RT

Corrections from an NTRIP service provider are typically transferred to an RT over a serial connection. If connecting to the RT through a serial connection is not desirable, you can forward the corrections to the RT unit using the network connection to the RT. The disadvantage to configuring the unit in this manner is there is no way to forward the GGA information real time to the NTRIP network such that the closest station can  selected for corrections. This configuration is best suited for a test where one station would be sufficient to use for the range of locations that the test will be performed in. You can manually enter a Latitude and Longitude in to the NTRIP client which will send the GGA signal required to select the appropriate station for the location of the test.

1. NTRIP Net DGPS Diagram
2. Configure the RT to receive differential corrections utilizing Networked DGPS
3. Download and Install Tibbo Device Server Toolkit (TDST)
4. Configure Network Connection
5. Configure the NTRIP client to use the virtual serial port

 

NTRIP to Net DGPS Diagram:

 

 

 

Requirements:

• RT unit runnig RTBNS with firmware version of at least 150527 or XBNS with xDEV version 170726 or later.
• Feature code for the unit to use Network DGPS (contact info@oxts.com if you need more information)
• Laptop computer with an NTRIP client – Lefebure or RTK lib STRSVR.
• Tibbo Device Server Toolkit (TDST) Software which can be downloaded from the following web site: TDST software
• A network connection to the RT unit. This connection can be a direct wired connection or you can connect wirelessly if there is a wireless access point connected to the RT.
• Wireless internet connection.
• An account with an NTRIP service provider or your own NTRIP caster.

 

Procedure:

1. If you do not already have the feature codes for Net DGPS, apply the feature codes to the RT.

Configure the RT to receive differential corrections utilizing Networked DGPS.

• Open NAVconfig
• Select Read initial settings from device and choose the appropriate IP Address for the RT from the drop-down menu.

• Navigate to the Options Section
• Click on the box with 3 dots in it, in the differential row to open the differential corrections settings.

• Set the Correction Type to RTCMV3
• Click the check box for Network correction receiver
• Enter the IP address of the computer that will be used to forward the differential corrections over IP. This option will not be available if your unit is running XBNS. If your unit is running XBNS, you will have to input this value via advanced command which will be shown in a following configuration step.

• Click ok
• Click on the box with 3 dots in it, in the Advanced row to open the Advanced commands settings.

• Enter in the following advanced commands if your unit is running RTBNS
• -diff_udp_wrapper_plain
• -diff_udp_port50490
• Click on Commit
• Select the IP of the RT in the drop down menu and commit the settings

• Enter the following advanced commands if your unit is running XBNS
• -udp_corr_addressXXX.XXX.XXX.XXX (the series of xes to the left is the IP of the computer that will be forwarding the corrections over UDP)
• -udp_corr_port50490
• -diff_format_rtcm 
• -diff_udp_wrapper_plain
• -diff_send_gps1 
• Click on Commit
• Select the IP of the RT in the drop down menu and commit the settings

 

 

Download and Install Tibbo Device Server Toolkit (TDST).

 

• Download TDST by clicking on the link shown in the screen shot below. The URL for the download is: http://tibbo.com/support/downloads/tdst.html

 

  

• Locate the file in your download directory and right click on it and choose Run as administrator.

• Click on “I Agree”
• 

 

• Click on “Next”

• Click on “Install”

 

• Locate the Tibbo program group in the Start Menu and click on Tibbo VSP Manager.

• If you see the following dialog box, click ok.

 

 

• Create a virtual com port which will be used by the NTRIP client by clicking the add button.

• In the VSP properties tab you want to change the following settings:
• VSP name – this sets the com port number, make sure to choose a com port number that is not already in use. I selected com 10 in this example.
• Transport protocol – choose UDP
• Routing mode – choose Client
• On the fly commands – choose disable
• Destination – Specify by – choose IP address – IP address – Input the IP address that matches the subnet of the RT and terminate the IP address with 255 such that you send the UDP packets over the broadcast address. To the right of the IP address input the port number which is 50490

• Click on the Tab labelled Default Serial Settings
• Change the baud rate to 115200 bps and then click ok.

 

 

• The following window should display the virtual serial port you created.

• You can now close this window. The virtual serial port will still be active in Windows.

 

Setup the network adapter to the correct subnet for communication with the RT.

 

• The format of the IP address for an RT is 195.0.0.xxx where xxx generally contains the last two digits of the serial number of the RT. To avoid IP address conflicts, set the IP on the computer’s network card to an address in the 195.0.0.xxx range that doesn’t include the last two digits of any serial number RT that will be used in your test configuration. The upper limit of the number that can be used in the xxx region of the IP address is 254.
• Go to Control Panel > All Control Panel Items > Network and Sharing Center

• Click change adapter settings

• Right click on the network adapter that will be used to connect to the RT and select properties.

  

 

• Select Internet Protocol Version 4 (TCP/IPv4) and click Properties

• Enter the IP address in the IP address field. In the figure below 195.0.0.115 is selected but this is just an example. Make sure to select an IP address that will not conflict with any of the IP addresses on the RT network.

• Click “ok”

• Click “ok”

  

Configure the NTRIP client to use the virtual serial port:

 

• This guide does not include instructions on NTRIP client install and configuration so if you require information on setting up an NTRIP client, please refer to the following article on our help center. NTRIP Overview

  

 

• The screenshot below illustrates the configuration for Lefebure NTRIP Client. Select the com port number of the virtual serial port that you created and input the correct baud rate which is 115200.

 

• Manually input the Lat and Lon of your location for the GGA string

 

• Once this is configured you can click ok and connect to the NTRIP stream and serial port. Once the connection is established you should see a screen that looks something like this.

 

• Using this specific NTRIP client is not required, this is just an example. The virtual serial port created will work with any NTRIP client.

The setup is complete. The next step is to check to see if the differential corrections are being received by the RT. Connect to the RT unit using NavDisplay and check the solution mode and the differential age. The differential age should read a reasonably low number and your solution modhould read as RTK Int (6)

In the screen shot above you can see that the unit is receiving corrections because the Diff age is reading .9 seconds. The solution mode isn’t ideal in this example but that is due to poor GPS signal where I setup this test.