Setting up a Base Station

GPS / RTK / GNSS
8

Here’s how I configured my base station ZED-F9P. There are no doubt other variations people use. I’ll look up your radios and see what they need a bit later.

  1. launch U-Center and connecting to the ZED-F9P, select “View->Configuration View”
  2. select PRT (Ports)
    • Select Target UART2
    • Make sure Protocol out is “5 - RTCM3”
    • Set baudrate to 115200 (the default for your radio modules)
    • Click “Send” button
  3. select MSG (Messages)
    • For each of the following message types, select them in the “Message” drop down box, then make sure UART2 is checked, and put the number listed in the input box next to the check box, which specifies how often to send the message. Note that for other kinds of roving receivers there might be a different set used. But for ZED-F9P rovers, MSM7 works nicely and you have enough bandwidth on those radios for all of this. Other radios (including Lora) might need a reduced message set
      • “F5-05 RTCM3.3 1005” 10
      • “F5-05 RTCM3.3 1077” 1 — GPS observations
      • “F5-05 RTCM3.3 1087” 1 — Glonass observations
      • “F5-05 RTCM3.3 1097” 1 — Galileo observations
      • “F5-05 RTCM3.3 1127” 1 — Beidou observations
      • “F5-05 RTCM3.3 1230” 10 — Glonass code biases; not sure if this is required for any modern GPS receiver
    • click “Send” button
  4. Select “RATE (Rates”
    • For each time source in the drop-down box, set measurement period to 1000, set Navigation rate to 1 cyc.
    • This will set the base message rate to 1 per second, which is what you want for the RTCMv3 messages coming from the base station
    • click “send”
  5. Select “TMODE3 (Time Mode 3)”
    • If you want to do a survey to find the average base station coordinate, select mode “1 - Survey-in”). This can be changed to a fixed location later when the base station is permanently mounted
      • Set the minimum observation time to at least 120 seconds
      • Set the Required Position Accuracy to 1 metre. You can make this finer but honestly it doesn’t need to be. RTK is all about relative accuracy, not absolute.
      • Click “Send” This should start the survey process. See step 7 for how to monitor the process
    • If you want to set the base station location (perhaps using Google Earth as a reference), select the mode to be “2 - Fixed Mode”
      • check the box that says “Use Lat/Lon/Alt Position” if you have coordinates in that form from Google Earth
      • enter the latitude, longitude, and altitude in the fields, or if you’re trying to make a survey-in permanent, enter the ECEF coordinates (see #7 below)
      • click “send”
  6. Save settings to flash very important
    • Select “CFG (Configuration)”
    • Select “Save current configuration” radio button
    • Select “0-BBR” and “1-FLASH” under devices (should already be highlighted)
    • Click “Send”
  7. How to monitor survey-in process
    • From main menu select “View->Messages View”
    • Find “UBX” in the list and double click it.
    • Select “NAV (Navigation”), “SVIN (Survey-in)”
      • click the “Poll” button to refresh the information.
      • when complete “Mean Position Valid” field should say “Yes”
      • can use the the ECEF coordinates as a “Fixed Position” in step 5 above to make the base station position permanent.
  8. Download configuration file in case you need to set up a new base station later
    • From the main menu select “Tools->Receiver Configuration”
    • Set the file name you want
    • Click “Transfer GNSS->File” button
    • Can upload a save configuration with the “Transfer File->GNSS” button
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