Feng Jun had secretly released this new tracker a couple of days ago and found that marked Qing brick mentioned by the Big Boss.
After finding the Qing brick, he specifically used a mobile phone to derive the method, finding relevant information with some difficulty.
Why was it difficult? Because he tested many search methods, like "divine sense nearby," "resonance nearby," "coordinates nearby," and so on... Finally, a stroke of genius led him to use "electromagnetic field nearby," which revealed the difference.
That vaguely black-lined Qing brick had a weak electromagnetic field, or rather, an electromagnetic induction effect.
As a humanities student, Feng Jun doesn't understand much about electromagnetic fields, but he can be sure that this is the mysterious aspect of the Qing brick.
Thinking about how the Taiqing Sect could locate such a method, he felt quite impressed. In a place without modern technology, someone could actually use electromagnetic waves like this.