Navigational Fix

Hi guys, supposed i’m going to make a robovac and I want to know its position everytime by sending out signals to three stations.

Is there a module that sends out signal and then measures back how far it is to that station? Any device would be really helpful Thanks

Pozyx

is there any cheaper than Pozyx? using the same technology

reycreator17: is there any cheaper than Pozyx? using the same technology

If such a device could be made cheaper, using the same technology, don't you suppose that it would have been?