RTK Radio Base Station Tutorial

FreeFly RTK Base Station Configuration

On Windows: Configure Base Station NVM to Output RTCM 3:

1. Download or clone this repo.
2. Download and install v22.07 of u-center for "F9/M9 products and below". u-center is u-blox's GNSS evaluation software (Windows only). We will use u-center to configure the basestation to output RTCM 3 on startup (OS independent).
   
3. Plug in FreeFly RTK GPS base station first, via USB
4. Open u-center and select the newly initialized COM port.
   
5. Click Tools > Receiver Configuration...
   
6. Click the directory browser and select Freefly_RTCM_MSM7_config.txt where you have cloned this repo.
   
7. Click "Transfer file -> GNSS".
   
8. Click the circled save settings to Non-Volatile Memory button:
   

On Windows: Survey in the Base Station:

Surveying in a basestation is a critical step to obtaining accurate global coordinate frame RTK corrections from a base station. Once the base station is physically installed in its stationary location, there are multiple options for surveying in the base station depending on accuracy requirements. If only relative position accuracy is required, then a quick survey is sufficient. If global position accuracy is required, then a longer survey must be performed. The higher the global position accuracy required, the longer the basestation must survey in its global position.

Option 1: Quick Survey (60 s) [RECOMMENDED]

1. The FreeflyRTCM_MSM7 configuration file enables an accelerated survey of 60 s. For applications with non-exacting position requirements, this option may be sufficient. For applications that require higher precision, Option 2 or 3 are recommended.
   

2. Click View -> Messages view

3. Click NAV -> SVIN

4. Wait until Status: shows Successfully finished (nothing will be output until the device starts outputting RTCM3 messages)

5. Verify in upper right hand corner that Lon, Lat, Alt and 3D Acc are acceptable for current location

Option 2: NTRIP Initialized Survey

1. This option is recommended only for the most demanding position accuracy applications. It does provide the most accurate position with zero survey-in time by supplying an accurate RTK position solution via NTRIP corrections. Note: This option requires that the user does not move the reference station after setting its position and the configuration does take significantly longer than Option 1.
2. Instead of above section, select Receiver -> Action -> Revert Config
3. Click Receiver -> NTRIP Client
4. Enter NTRIP caster settings
5. Update Source Table
6. Select NTRIP mount point
7. Click OK
8. Click View -> Messages View
9. Double click PVT (Navigation PVT Solution)
10. Wait for device to achieve 3D/FIXED in righthand status bar
11. Double click POSECEF (Position ECEF)
12. Copy out coordinates and accuracy from respective fields to temporary txt file
13. Load in config file and overwrite survey in values
14. Click Tools -> Receiver Configuration
15. Select Freefly_RTCM_MSM7_config.txt file
16. Click Transfer file -> GNSS
17. Click View -> Configuration
18. Select Group -> CFG-TMODE3
19. Select Mode -> 2 - Fixed Mode
20. Enter values for Fixed Position X, Y, Z, and Accuracy respectively
21. Click Send the Message button
22. Click Save Current Receiver configuration button in upper left hand tray
23. Restart the receiver
24. Click View -> Messages
25. Verify some RTCM3 messages are bolded
26. Click TMODE3 to verify device has saved survey position

Option 3: Long Survey (24 h)

1. The Long Survey option provides a configuration file for a 24 h survey to enable high accuracy position.

byte_shuffle

This directory is a byte shuffler intended for use with a GQ7-GNSS/INS and an RTK basestation equipped with radios, such as the FreeFly RTK GPS basestation and FRX PRO Pair 900 MHz radios. This tool is intended for convenience only and there is no affiliation between Parker and FreeFly.

Remember, RTK corrections can only be transmitted to the GQ7 via the AUX port. The AUX port provides an independent communication channel for RTK correction information and the flexibility of direct connection of radio basestations that this tool supports. The GQ7 supports the RTCM3 messages listed on the AUX/RTCM3 page of the manual.

WARNING: Do not connect the same power supply inputs (Vpri or Vaux) to different power supplies. Damage to the device and/or connected equipment may result from improper power supply connection. See the Powering page of the GQ7 manual on properly powering the 3DM-GQ7.

Instructions for use of this repo:

1. Download NodeJS
2. If Node package manager not installed in Step 1, install Node package manager
3. In byte_shuffle client directory, run in command line:
   • npm install
4. Edit node_byte_shuffle_client.js for correct serial port names
5. Run in command line:
   • node byte_shuffle_client.js

System Setup Block Diagram