DIY Wireless Containment System

Hello all! Greetings from Texas.

This is my first post here. I'm not 100% sure that this is the right place to post but it looked to be the most applicable to my situation.
I have very limited electronics experience as I have only done minor builds in the Remote control vehicular industry. Minor soldering, basic circuits, etc.

I have been approached by a friend that really wants to build a "wireless containment fence". We have sat down and have came up with the initial idea, that there needs to be a central beacon that transmits a signal that is receivable by the individual nodes or "trackers". The beacon will need to be able to adjust range from 10 meters all the way out to 1000 meters. When the trackers cross the boundary, they will emit an audible beep and illuminate an LED. Very similar to an invisible fence for dogs. Has anyone here ever built something similar to this?

Is this something that seems feasible by 2 amateur hobbyists? Or have we bitten off more than we can chew?


Any help or insight would be appreciated!

Helloooo Texas!

It sounds simple but it isn't, unless you are in the middle of a flat desert. The concept that the signal gets weaker as you move further from the source is good but the actual field strength depends on many other factors:

1. The radiating source needs to be omni-directional (equal amount of signal sent around 360 degrees ).
2. The receiving 'tracker' must be able to receive equally in all directions.
3. There cannot be any obstructions between them that would shadow the signal.
4. There must be nothing in the vicinity that can reflect or deflect a signal as it would create signal 'hot spots' and 'not spots'.
5. The frequency must be clear of interference.

Even getting equal sensitivity in all directions can be a nightmare, you are constrained to using vertical antennas with equal ground plane areas around their base, otherwise as the tracker rotates, the signal strength will vary and the distance estimate will be wrong.

If you want to experiment, find a signal source (as signal generator for example) and attach it to an antenna. Then using a receiver with a signal strength indicator, move around the room and in the wider area. Use Google Earth or similar and print a satellite image of say 1,000m across and plot the strength readings you get at different places around it. You should be able to join the spots to make a contour map of coverage. I think you will see how difficult it can be to use received signal strength as a distance indicator.

Probably a more practical solution is to use a GPS module as they are so cheap these days. Then write some software to calculate distance from the center of your containment area. The advantage is it doesn't require a transmitting source so it is license free and by entering a center coordinate, it works anywhere in the World. With care you can even define a perimeter shape instead of just a circle.

Brian.

This is genius! SO much more simple than what we were thinking of. Thank you for your reply! Now to brush up on my coding



Do you know someone that would be willing to build a large quantity of these modules for me? And setup an app or software to run it? I would be willing to pay a fair price for their services. I am currently in school and work a full time job as well. Time is a rare commodity for me now a days lol.

I've been retired for 18 years - count your blessings, you will find in due course that work expands to fill the available time. I've never been so busy in my life as now!

I don't know anyone who can help with building modules, especially as I'm on the other side of the Atlantic Ocean but your message will be read by thousands of people so there is a good chance someone will come forward with an offer.

Brian.