I'm looking for a Free/Open-Source program for recording GPS coordinates from an external GPS antenna plugged into a laptop via USB and display them on a map in real-time. Must be able to work offline as cell coverage is unreliable. Ability to label/annotate the points would be a plus.
Tried using Google Maps & Google MyMaps to place pins using a cell phone, but whenever I have poor cell signal I find that the pins are off by as much as 50 ft.
There are a myriad of GIS programs out there, but its not clear to me which ones support USB GPS antennas.