Set up the DigiTerra Explorer 7 and Topcon GRS-1

With the progress of the Topcon TRU software, we have the opportunity to make the settings of the GRS-1 without using eGPS software. The settings themselves aren’t difficult, but need some knowledge.As first, we have to know what we had bought. The Topcon GRS-1 is available in many configuration, from submeter to two frequencies RTK (cm).The most cheaper solution communicates on one frequency with GPS and GLONASS satellites. It’s not containing a built-in camera or GPRS modem. But thanks of progressing of the mobile phones, we can use our mobile as a WIFI hotspot. As GRS-1 has WIFI connection, we can easily connect to the internet –it is possible to reach the correction sings of the NTRIP provider. In the first chapter, instead of using the correction of NTRIP we use SBAS correction to make the settings. It’s reachable for everyone and in case of good conditions, approximately we can be within 80 cm.

1.      CHAPTER 1 - Settings of GRS-1 with free satellite correction (~80 cm)

  1. Open start menu in GRS-1, then click on Programs command. Here, we can find the Topcon Receiver Utility (hereafter TRU) software, so we can access to the GNSS chip settings.
  2. After starting the program click on ‘Device’, which you can find in the left-bottom corner, then choose ‘Connect’ from the menu.
  3. Select COM6 as connecting port, then click on Connect.
  4. After connection it is possible to reach the setting opportunities, and we can check the purchased options in the Options window.
  5. Click on Receiver Settings icon. Click on Tracking icon, where we can set the visibility of SBAS satellites.
  6. In the current view we can see several tabs. First, click on Antenna, here we define using internal or external antenna during the measurement. Now, we use the Internal option, which means the internal antenna.
  7. Select the SBAS tab. Here we can select from SBAS satellites. Above Hungary the following satellites are in use:
    • 120
    • 124(ARTEMIS)
    • 126 (Inmarsat 4F2)
    Then click on OK, so we step back to the previous window.
  8. Next step is the menu Positioning. After entering the menu, set the Positioning mode. Select Code Differential. Select all the options in Enable Solutions (RTK Float and RTK Fixed options are grey, and already selected). Then click on OK, so we get back to the previous window.
  9. Clicking on the Ports icon, we can set what kind of NMEA sentences should the GNSS chip send to DigiTerra Explorer through the port. From the list, open the option serial, then double click on dev/sec/c line.
    1. From the Input mode select option None from the dropdown list.
    2. From the Output mode select User defined option, then click on button Messages
    3. Tap and hold the stylus then click on Add new messages.
    4. From the list select NMEA option and make double click to add the following options:
      • GGA
      • GLL
      • GSA
      • GST
      • GSV
      • RMC
      After that close the window.
  10. Get back to the main menu, click on Device and select the Exit command for exiting from the TRU.
  11. In the bottom right corner of the device monitor, we can find a globe icon with 3 red lines. Push the icon, if it’s not selected, push the Connect GPS receiver command. This way, we turn on the GPS receiver.
  12. Start the DigiTerra Explorer. From the settings GNSS tab set the Port value to COM 7 and baud to 115200.
 

2.      CHAPTER 2 Settings of the GRS-1 with DGPS or RTK correction (~ within 30-40 cm or 1 cm)

Repeat the steps from CHAPTER 1 until step 7. Activating the SBAS satellites is not needed.
  1. Next step is the menu Positioning. After enter the menu, first set the Positioning mode. Select Code Differential. Select all the options in Enable Solutions ( RTK Float and RTK Fixed are grey, and already selected). After we finished the step, click on OK, so we get back to the previous window.
  2. Clicking on the Ports icon, we can set what kind of NMEA sentences should the GNSS chip send to DigiTerra Explorer through the port. From the list, open the option serial, then double click on dev/sec/c line.
    1. From the Input mode select option RTCM from the dropdown list.
    2. From the Output mode select User defined option, then click on button Messages
    3. Tap and hold the stylus then click on Add new messages.
    4. From the list select NMEA option and make double click to add the following options:
      • GGA
      • GLL
      • GSA
      • GST
      • GSV
      • RMC
      After that close the window.
  3. Get back to the main menu, click on Device and select the Exit command for exiting from the TRU.
  4. In the bottom right corner of the device monitor, we can find a globe icon with 3 red lines. Push the icon, if it’s not selected, push the Connect GPS receiver command. This way, we turn on the GPS receiver.
  5. Start the DigiTerra Explorer. From the settings GNSS tab set the Port value to COM 7 and baud to 115200.
  6. Click on NTRIP tab. Make sure, that the Port value is COM7, and the baud value is 115200.
  7. Set up the IP address, the user name and the password what you get from the local NTRIP provider.
  8. Please note, that we can only get correction signs in RTCM2.1 and RTCM2.3 format. By selecting the Mount point we have to take care about it.

3.      CHAPTER 3-  Settings of the GRS-1 with RTK correction (~ within 1 cm)

Repeat the steps from CHAPTER 1 until step 7. Activating the SBAS satellites is not needed.
  1. Next step is the menu Positioning. After enter the menu, first set the Positioning mode. Select Code Differential. Select all the options in Enable Solutions ( RTK Float and RTK Fixed are grey, and already selected). After we finished the step, click on OK, se we get back to the previous window.
  2. Clicking on the Ports icon, we can set what kind of NMEA sentences should the GNSS chip send to DigiTerra Explorer through the port. From the list, open the option serial, then double click on dev/sec/c line.
    1. From the Input mode select option RTCM3 from the dropdown list.
    2. From the Output mode select User defined option, then click on button Messages
    3. Tap and hold the stylus then click on Add new messages.
    4. From the list select NMEA option and make double click to add the following options:
      • GGA
      • GLL
      • GSA
      • GST
      • GSV
      • RMC
      After that close the window.
  3. Get back to the main menu, click on Device and select the Exit command for exiting from the TRU.
  4. In the bottom right corner of the device monitor, we can find a globe icon with 3 red lines. Push the icon, if it’s not selected, push the Connect GPS receiver command. This way, we turn on the GPS receiver.
  5. Start the DigiTerra Explorer. From the settings GNSS tab set the Port value to COM 7 and baud to 115200.
  6. Click on NTRIP tab. Make sure, that the Port value is COM7, and the baud value is 115200.
  7. Set up the IP address, the user name and the password what you get from the local NTRIP provider.
  8. Please note, that we can only get correction signs in RTCM3.0 or RTCM.1 format. By selecting the Mount point we have to take care about it.