Back in June, MIT researchers revealed they had figured out how to use Wi-Fi to track moving objects through walls. Today, the same team announced they have refined their system to be even more precise by switching to radio signals.

The system, known as “WiTrack,” works with the help of four antennae. One transmits a signal and the other three take in signals that bounce back. Based on how long it takes a signal to return, WiTrack can calculate an object’s distance from the antennae and map movement.

“Because of the limited bandwidth, you cannot get very high location accuracy using Wi-Fi signals,” graduate student Fadel Adib said in a release. “WiTrack transmits a very low-power radio signal, 100 times smaller than Wi-Fi and 1,000 times smaller than what your cell phone can transmit.”

Along with improving the precision of the tracking to 4 to 8 inches, WiTrack’s advantage…