Emlid.com

https://community.emlid.com/t/3dr-solo-with-reach/1846/25

http://diydrones.com/profiles/blogs/reach-rtk-gps-can-now-embed-ground-control-points-in-imagery Reach was built with precision mapping applications it mind. One of the big challenges in UAV mapping is eliminating Ground Control Points which are time consuming and costly to place. Reach RTK can help achieve that by synchronizing with the camera shutter on sub ms level. I have written more about this in a previous post. All you need to do is connect hotshoe adapter to your camera and wire it to Reach port. Only two connections are required "GND" and "Time Mark". During RINEX conversion on Reach you will see a new field that will show how many time marks have been collected. That should match the amount of pictures taken by the camera. Those of you who have access to GrafNav can already start mapping and getting accurately georeferenced pictures. Thanks to @Stu74 we know that it parses time marks from RINEX and interpolates the post processed coordinates. We have also implemented this feature in RTKLIB and will release modified RTKPost soon.

https://emlid.com/reach/ Main function of Reach is to compute precise coordinates. To do so it uses technology called RTK – Real-time kinematics. Two connected receivers within 10km radius are used and static device streams corrections to the moving one. You can simply connect one device to your home router and another one to a smartphone with web access.

RTKLIB is an amazingly powerful open-source software written by Tomoji Tokasu for RTK and postprocessing. Algorithms used to determine accurate position are computational intensive and RTKLIB was mostly used on PCs and laptops. We have created a tiny, yet very powerful module that runs RTKLIB and locates your position with centimeter precision.

https://www.indiegogo.com/projects/navio-autopilot-shield-for-raspberry-pi#/ NAVIO: Autopilot Shield for Raspberry Pi Control cars, boats, multirotors, planes and other kinds of drones directly from your Raspberry.