FYI
You don't need the GPS connected and running, you only need a valid location so the incoming packets will show a meaningful bearing and distance. Load MY POSITION and then you can proceed with the next youtube.
Copy and paste from the PDF manual.
When the GPS receiver is not connected to the TM-D710(fixed station), set the GPS receiver Menu No.602(GPSPORTINPUT) to [OFF] (default value). If you do not connect the GPS receiver when you set up [GPS], your station position location will not be correct, and the distance and direction of other stations will not be displayed. Therefore, you should set your position data using Menu No. 605 (MY POSITION).