I would like to setup a perimeter to define the area that a robot is allowed to travel inside of. This will be outside in an odd shaped "fence" and I need accuracy down to about 1-2 feet (30-60 cm). Given these requirements, I don't think GPS will allow me to reliably achieve my goal, but if someone thinks otherwise, I'm certainly open to that idea.
Instead I'm thinking that an underground wire that transmits on a very low power/frequency (e.g. in the kilohertz range) and a receiver on the robot that can detect this signal at the appropriate distance would be a good solution. This is basically the same idea as an invisible fence for a pet. My problem is that I don't know much about how to build the transmitter / receiver combo and everywhere I look I see people saying that it's a very difficult thing to do and that other solutions should be tried. I get that it might be hard to do, but I don't want that to stop me. This (
http://www.philohome.com/sensors/filoguide.htm) is basically what I'm looking to do, but I'm not sure how to scale / change that solution to a defines a perimeter around a ~8,000 square foot area.
I'm looking for one or more of the following:
a) a nudge in the right direction to help me understand what I need to do
b) suggestions on books to read that can help me get started in the RF space. My current level is a hobbyist who understand the basic principals of how RF works but I need to go deeper. I don't have any practical experience building RF devices
c) a prebuilt device that could accomplish the same goal - although I prefer not a hack an invisible fence dog collar since that feels kind of like cheating to me. Ultimately, having something that is capable of delivering an electrical shock isn't something I want as a part of my solution.
d) suggestions on tools that I will need to learn and build this solution (e.g. should I invest in a spectrum analyzer etc?). I already have a fairly basic Oscilloscope, is that enough?
e) other items that I should be thinking about but don't know to ask about
Thanks!