Big data will be discovered. All kinds of health codes are basically docked communication big data travel cards, which are not subject to geographical restrictions and do not collect ID numbers and home addresses. As long as you enter the mobile phone number, you can get the travel information of the past 14 days according to the communication network data. The principle is that the location of the user's mobile phone can be effectively located based on the mobile phone signaling data, so as to find the owner himself.