Ultra-low cost precision GPS
I am using this blog to document my work with RTKLIB and in the hope it may prove useful to anyone else trying to get started with this excellent open source program.
I describe the blog as “ultra-low cost precision GPS”. Several other blogs describe work on precision location with sub $100 GPS receivers but most if not all of these use relatively high quality antennas which can significantly increase the total cost.
The hardware I am using is available for $25 to $30 dollars total which includes both receiver and antenna. I believe this hardware requires some enhancements to RTKLIB to improve robustness, and that is what I focus on in these blog posts. As the blog has progressed I have expanded from just ultra-low cost to some slightly more expensive options including better receivers, antennas, and inclusion of radios.
There is a mix of information here, some of which is intended for those just getting started with RTKLIB and other posts that might be of interest for more advanced users. For those just getting started, I suggest clicking on “Getting Started” listed in the categories section part way down the right hand side on the main page. This will bring up all the posts I have geared towards a new user. Unfortunately the most recent posts appear at the top, so you will need to scroll to the bottom and work your way up.
I would be very interested in hearing about other similar work, so please leave a comment or send me an email at firstname.lastname@example.org if you are working in this area or if you have anything to add to any of the posts. My goal is also to document as completely as possible the work I have done, so if there is something I have skipped over that would be of interest to others, please let me know, and I will try to add a post.
All of the code changes and configuration files described in my posts are available in my Github repository. The most recent executables are available here and most of the data sets I reference in the blog are here.
A little about my background: After 25 years in the disk drive design business I was ready for a change. I was looking for something different enough to offer new challenges but not so different that I couldn’t leverage my previous experience. Precision GPS turned out to be a natural fit since my specialty in disk drive design was precision positioning, both putting down the reference tracks in the manufacturing process, and minimizing errors in the drive while following them. The scale is very different with GPS, millimeters or centimeters over kilometers instead of the nanometers over centimeters I used to work with but they also have much in common. The details are all different of course, but the kalman filters at the core of RTKLIB are just extensions of the state-space estimators I used extensively in my previous life. In addition I find many of the techniques and approaches I used to solve problems at the microscopic scale are very applicable at the macroscopic scale of GPS. I considered going back to school to make the transition but eventually decided I preferred this format. So far I have found the challenges extremely interesting and also very rewarding to be able to see other people use some of my results. Eventually I will have to figure out how to make a living again, but for now I am happy doing this work for its educational benefits.