Police Scanner Codes - Police Scanner Codes, Introduction A police scanner is a radio receiver able to tune or scan frequencies. It monitors UHF and VHF hand-held mobile radio systems. It can receive messages one at a time, and send out multiple signals at the same time. A scanner device is further enhanced with the use of codes, like number or color codes. To reduce the negative effects of radio static, short codes are used. Police scanner color codes reduce sentences and phrases into two-word signals. Common Police Scanner Codes Code 2 U.