So they bought a scanner. These are perfectly legal and they run at the frequency of the P25, and what they did is they hopped around frequencies and they wrote software to listen in.
他们买了一个扫描仪。这些都是完全合法的 他们并在P25的频率下运行这扫描仪， 之後他们在这个频率周围不停地转动 然後用他们所写的软件来监听。