Yesterday I ordered some additional GPS receiver modules. One uses a Ublox NEO-7M and the other uses a NEO-M8N. The 7M uses lower power than the 6M. The M8N is also lower power consumption than the 6N, has slightly better receive sensitivity and acquisition times, and has a claimed position accuracy of 2m. The one downside to the NEO-M8N is the cost. It is about 72% higher than the 6M or 7M but it is still an inexpensive unit. One nice thing about the two new modules is they are fully compatible with the 6M so I will be able to interchange the GPS receiver modules and run various performance tests on the three units.

I haven't made a lot of progress in the last few days as I have been working on creating some 3D models for parts and assemblies used in this project, creating part footprints for Kicad, and working on the the PCB layout. I know how I want to position the connectors and controls on the final product. Using the additional 3D models and Kicad component footprints to place parts on the PCB resulted in a change to the size of the interface board. I had to widen it by 0.2" and also increase its depth by 0.1" to make room for the slide switch, push button, LED, and two USB connectors. I still need to source a slide switch and right angle push button and create 3D models and Kicad footprints of both in order to finalize the PCB layout.

I am going to take a break from the hardware side of the project for a few days and work on the software.