NTRIP overview with a smart phone

This article tackles NTRIP and the ways in which it can be used with OxTS navigation systems.

1. NTRIP overview
2. Using NTRIP with a smart phone
3. Configure the INS
4. NTRIP PC caster GUI Applications

NTRIP Overview

NTRIP (Network Transport of RTCM via Internet Protocol) is a form of RTK differential correction that transmitted using the TCP/IP protocol (e.g. Ethernet / WiFi networks)

This means that instead of using the traditional base station and radio to send correction data to a rover, data is sent using the internet to a cellular modem with a data plan. The NTRIP corrections can then enable you to reach RTK accuracies where using a base station is not feasible

Using NTRIP with a smart phone

Equipment required

• OxTS unit capable of taking corrections associated antennas and cables
• 15-way to 9-way serial adapter cable
• Bluetooth RS232 serial adapter (LM Technologies LM048 Bluetooth used here)
     

• NTRIP client program
  • PC - Lefebure NTRIP client recommended
  • Android - Lefebure NTRIP app recommended
• Mobile data link , either Wi-Fi or mobile data link

Configuring the Bluetooth adapter

Configure the Bluetooth RS232 serial adapter

The screenshot and instructions given in this section are specific to the LM149 Configuration Tool. Different Bluetooth RS232 serial adapters may require different configuration.

Connect the Bluetooth RS232 serial adapter to a serial port. Select the COM port in the software and select Read Settings. Typically a baud rate of 9600 bit/s is used with differential corrections. Also make a note of the device name and pin code. All other settings can be left as default.

Setting up the INS

• Set up the INS in your vehicle
• In NAVconfig, on the Options page in the Differential window, select your correction type and tick the box to enable NTRIP corrections (see Figure 3).
  

• Connect your 15-way to 9-way serial adapter cable to the J3 Radio/Differential port of your INS.
• Connect the Bluetooth serial adapter to the other end of the 15-way to 9-way cable. It may be necessary to power the Bluetooth serial adapter via USB if power isn't supplied by the cable.

NTRIP corrections via laptop

Any instructions and screenshots in this section are specific to the Lefebure NTRIP Client executable program. This process requires a laptop with Bluetooth capability and a Wi-Fi or cellular data link.

• Pair the laptop with the Bluetooth RS232 serial adaptor over Bluetooth.
• Launch the NTRIP client (see Figure 4).
  

• Select the Edit Serial Port option (see Figure 5), and select the virtual serial port which the Bluetooth RS232 serial adapter is using.
• Ensure that the correct baud rate is set for the serial port. This must match the baud rate of the Bluetooth RS232 serial adapter and the differential port of the RT. The default baud rate for these is 9600 bit/s.
  

• Click OK, then select the Edit NTRIP Stream option (see Figure 6).
  

• Select NTRIP v1.0 protocol and use position data from serial port.
• Enter the NTRIP caster settings which usually must be requested from the NTRIP service provider.
• Click OK.
• In the NTRIP Stream drop-down menu, select Download Source Table. This will contact the NTRIP caster and download a list of available differential streams.
• Click the Connect button for the serial port, then Connect for the NTRIP stream.
• When the source table has populated, select a differential stream and click the Connect button for NTRIP stream again.
• Your system should now be receiving differential corrections.

NTRIP corrections via smart phone

Any instructions and screenshots in this section are specific to the Lefebure NTRIP Client Android smartphone app. This process requires a smartphone with Bluetooth capability and a Wi-Fi or cellular data link.

• Pair the phone with the Bluetooth RS232 serial adapter over Bluetooth.
• Launch the NTRIP client app (see Figure 7).
  

• Press the menu button of your phone then select Options. You will see the menu shown in Figure 8.
  

• Select Receiver Settings (see Figure 9), and set the Receiver Connection to External via Bluetooth, and if not done so already, pair your phone with the Bluetooth RS232 serial converter.
  

• Return to the Options menu, then select NTRIP settings (see Figure 10). 

• Set the Network Protocol to NTRIP v1.0.
• Enter the Caster IP, Caster Port, Username and Password. This must usually be requested from the NTRIP service provider.
• Under Data Stream, select Download Source Table. This will contact the NTRIP caster and download a list of available differential streams.
• Set Reported Location to Automatic.
• Return to front page of the app (see Figure 7) and click Connect.
• This will download a new list of available differential streams.
• Return to the NTRIP settings page (see Figure 10) and select a data stream.
• Return to front page of the app (see Figure 7) and click Connect.
• Your system should now be receiving differential corrections.

Configure the INS

The unit has to be configured to enable NTRIP corrections.

RT series units

During the configuration, in the Performance Options, change the Differential settings. (see Figure 11)

Change the Correction type to RTCMV3 and tick the Enable NTRIP corrections box. (see Figure 12)

This will enable the corrections and can be committed to the Unit.

xNAV250/550

During the configuration, in the Performance Options, change the Serial input settings. (see Figure 13)

change the input type to Differential (see figure 14)

Next, enable the Serial 1 output (see figure 15)

Select NMEA and configure the baud rate (see figure 16)

Then turn on the GPGGA message (see figure 17)

This will enable corrections, and enable you to commit them to the unit

Once configured you can verify that the corrections are being received using NAVdisplay.

Open the performance template and connect to your device. The measurement Differential GPS Age provides the age of the most recent correction packet, this ought to be less than five seconds. Note that a value of -1 means that correction have not yet been received. Providing you have a valid differential age you ought to also see your Position and Velocity modes as RTK Integer.

The NTRIP Corrections can also be shared over a Network. To do this, in the Differential settings of the unit receiving the correction over Bluetooth, select Network correction transmitter. For the Units receiving the corrections select Network Correction receiver. Some INS need to have the IP address of the transmitter unit to be specified from the drop down box next to Network correction receiver.

NTRIP PC caster Applications

There are a some various ways in you can set up your own caster currently the simplest way is to use 3rd party software.

3rd Party Applications

https://www.use-snip.com