trilateration | space trilateration problem using a nonlinear least squares | Learning library

I have this little issue that I cannot resolve. I've tried several things without any success. So, to put this into context:

I have a number of objects with known positions. In my set up, I even have devices calculating their position (trilateration, but it's not important to this question).

I have this project where I am trying to expand our app, that can transmit realtime location of the appuser by locating the position of the smartphone. I've spent several hours looking for the right kind of beacons, but I can't seem to understand which ones suits the best for my project.

What I am trying to achieve is to put beacons all over my workplace to be able to see the realtime location of everyone who uses the app within that area by using trilateration. I need to cover a large area of around 4.000m².

I am not looking for a pre-built software solution, but just the hardware to be able to integrate the tracking system into my already existing Android/IOS app.

So what I am trying to ask is what kind of beacon should I use. I've also seen some projects built with arduino, but it looks like they are all using an external transmitter, which is not what I am looking for. The smartphone with bluetooth enabled should be the only transmitter.

If you have any suggestions which beacon to go for, please let me know.

Thank you for reading and your help and have a nice day.

With best regards

Karuzo Rodriguez

I have 3 receivers (A, B and C), and some signal producing source (let's say sound or light) with an unknown location. Given the locations of A,B and C, and the time at which each receiver "heard" the signal, I'd like to determine the direction of the source.

I understand there are ways to do so with TDoA multilateration/trilateration, however I'm having trouble implementing the calculation. There isn't a lot of clear, detailed information on this out there for those entirely new to the subject. What is out there is vague, more theoretical, or a bit too esoteric for me.

Some similar posts on SO (but not quite what I'm after): TDOA multilateration to locate a sound source Trilateration of a signal using Time Difference(TDOA)

This is also interesting, but assumes we have some boundaries: Multiliteration implementation with inaccurate distance data

@Dave also commented an excellent and fairly accessible resource https://sites.tufts.edu/eeseniordesignhandbook/files/2017/05/FireBrick_OKeefe_F1.pdf, but it falls short of going into enough depth that one might be able to actually implement this in code (at least, for someone without deep knowledge of regression, finding the intersection of the resulting hyperbolas, etc).

[EDIT]: I should add that I can assume the 3 sensors and the source are on the surface of the Earth, and the effects of the curvature of the Earth are negligible (i.e. we can work in 2-dimensions).

There’s a game coming out called starbase that contains its own programming language. I’m trying to make a GPS system using at least 4 reference points. In the game there are receivers and transmitters that give distances. Essentially I have 4 known points with distances to a point. I know I can use trilateration but I can’t seem to find an actual equation that I can turn into code. If anyone can help that would be great :).