Network DGPS involves forwarding corrections from one device to another over ethernet (wired or wireless). This again is Feature Code protected and needs to be unlocked on both the transmitting and receiving unit. The unit transmitting units must be configured to receive corrections via the serial port or internal NTRIP client as these are the correction messages that will be forwarded.

When receiving Net DGPS, you must not receive corrections from another source (e.g. serial or internal NTRIP).

How to configure Net DGPS

To configure the unit as either a transmitter or a receiver you must select one of the options in the dropdown menu shown below.

Due to the capability of the xNAV650 and AV200, in order to forward corrections, the unit must receive corrections via the Serial Input page. Only once this has been configured can it transmit corrections as shown in the images below.

When using RTBNS based units, please add the following commands to the 'Commands' tab under 'Advanced Tools':

-diff_udp_wrapper_plain

-diff_udp_port50472

Using Net DGPS to forward NTRIP corrections

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't be 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.

When configuring the unit, only enable Net DGPS, and do not enable NTRIP. The laptop in this case will be receiving correction and forwarding them to the unit. In this case the unit is only aware corrections are being sent and not the original source

NTRIP to Net DGPS Diagram

Requirements:

• One of the following OxTS products:
  • RT3000/4000/2000 running rtbns with firmware version later than 150527
  • RT3000v3
  • A unit capable of running xdev
  • Please note - this method does not work for the v1/v2 xNAV products
• Feature code for the unit to use Network DGPS (contact sales@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.

Download and Install Tibbo Device Server Toolkit (TDST)

• Download and install TDST from the following link: http://tibbo.com/support/downloads/tdst.html
• 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 2 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. This is usually 195.0.0.255 or 192.168.25.255. To the right of the IP address input the port number which is 50472

• Click on the Tab labelled Default Serial Settings
• Change the baud rate to 115200 bps, or an appropriate number. 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, or 192.168.25.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.

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, or what you configured on the virtual serial port.

• Manually input the Lat and Lon of your location for the GGA string. Be aware that the unit will only receive corrections for the location chosen, with Lefebure acting as a base station. This will still give down to 2cm accuracy when up to 20 km, with an addition 1cm per 10km added to this. (e.g. 3cm at 30 km away, 5cm at 50 km). If open road driving is performed and you travel more than 20 km from the manual location, it is possible to change this mid data collection.

• 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 should read as RTK Int (6).