Chapter 941 (2/2)
The Municipal Bureau gathered a group of criminal police in an emergency, and the casual clothes began to leave the last place where Wei Lan left, that is, WANYING real estate began to investigate. At the same time, mobile operators began to actively cooperate.
The public security organ has the right to ask the operators to cooperate in retrieving the relevant information of all mobile phone numbers. Gu Jianghe attaches great importance to this matter. In the middle of the night, he calls the person in charge of Yanjing of the two operators and requests that senior technical personnel be dispatched to taobao.com immediately to fully cooperate with the public security in solving the case.
More than one o'clock in the morning, Taobao's sales just exceeded 300 million yuan. Yanjing principals of the two major operators arrived at Taobao with a few nervous operators' technicians, computers and other equipment. When they arrived, they immediately made a statement to Gu Jianghe, and would do their best to help the city Bureau solve the case.
Gu Jianghe immediately issued the first order: locate the location of Weilan's mobile phone.
After a moment's operation in the background system of mobile operators, the engineers and technicians said with a face of regret, ”the other side's mobile phone is no longer on the network, and we can't locate her specific location.”
Li Mu frowned: ”what is your base station location logic?”
The technician said: ”President Li, the base station location logic is to contact the mobile phone through multiple base stations, and then judge the approximate location of the mobile phone through the signal difference between multiple base stations and the mobile phone, such as a kilometer away from point a, 1500 meters away from point B, 1800 meters away from point C. draw a circle with the distance of three base stations as the radius. Finally, the area where the three circles overlap is It's the approximate location of the mobile phone, which is not accurate enough. The error is about one or two hundred meters. ”
Li Mu said, ”look at the base station record of Weilan mobile phone when it was last connected to the network, and then according to your method, can you guess the specific location?”
The technician shook his head and said, ”Mr. Li, our base station will not actively record the relevant information when the user enters the network, so there is no specific base station record in our background, only the record of the time when the user enters the network.”
Li Mu was very surprised: ”no record? Don't your base station record by default the information of the devices connected to the network in this base station? ”
The technician said awkwardly: ”to tell you the truth, Mr. Li, when you are working on the Internet, the background processing is not much worse than ours. You know, a device is in the city. With his daily life track, he has to frequently switch the base station dozens of times a day, or even more. If every time he accesses the base station, the base station has to record, the amount of data written is too large , it's hard for our database to do such support... ”After that, the technician explained: ”only in one case can our base station actively record user data.”
Li Mu asked, ”what's the situation?”
”Roaming...” The embarrassment on the technician's face was even more serious. ”The reason why users do not record when switching between base stations in the local area is that the amount of data written is too large on the one hand, and on the other hand, the cost is also considered. However, once a user arrives in a different place, the call will generate roaming charges. Therefore, in the roaming state, the base station will record his relevant information to charge users for roaming charges ……”
Chen Ze immediately exploded: ”I shit! Your operators are not good enough! If local users don't generate roaming charges, you will not record them. If roaming charges are generated, you will not record them once? ”
”This...”
The face of technical personnel is red, and the actual situation is true. Enterprises also serve for profits, and do not want to blindly store a large number of unprofitable records to increase costs and burdens.
Li Mu understands that there are hundreds of millions of mobile operators in China. If every user switches to and from the base station every day, the information will be recorded and written into the database, and the amount of data generated every day will be so huge that it will frighten people to death. Without the drive of interests, the operators will not invest so much to retain this meaningless data. Moreover, the greater the amount of data written, the greater the impact on the system The greater the impact and test of stability, so they only keep roaming data, which is in line with business and technical logic.
So, Li Mu said at this time, ”let's not talk about this. I ask you, since you didn't have a base station record when your cell phone was connected to the network last time, that means that Wei Lan's cell phone was still in Yanjing City, right?”
The technician nodded: ”the last time I entered the network, it was like this, but now it's turned off, so I can't guarantee whether it's still in the municipal area.”
Li Mu asked again, ”how long will it take you to locate the specific location if the other party's mobile phone is turned on and connected to the network again?”
”It will take at least two minutes,” the technician said
Li Mu is also about to explode: ”two minutes? Why? ”
The technician had to explain: ”just after entering the network, we can get the information of the default connected base station. The positioning method just mentioned requires at least three base stations to connect mobile phones for three-point positioning. When only one base station is determined, if it is a city, it may only be able to locate a range of one kilometer around. If it is a suburb, it may be It will locate a range of two kilometers or more, which is too inaccurate... ”
Li Mu asked him, ”so you need more than two minutes to determine the location, as long as you confirm the information of the first base station that is connected by default, and then let at least two nearby base stations connect to mobile phones?”
”Yes.” The technician nodded and said: ”the actual situation will be more complicated. Mobile phones only connect to one signal source at a time, i.e. one base station. So in order for mobile phones to connect to other base stations, we must first weaken or even shut down the signal of the first base station, then enhance the signal of other base stations, let mobile phones capture the signal and connect again. After confirming the information of the second base station Then shut down this base station, enhance the signal of the third base station to let the mobile phone connect. After the mobile phone connects the three base stations successfully, we can infer the specific location, which is equivalent to letting the three base stations successfully communicate with each other's mobile phones one by one, so the two minute time is an optimistic estimate... ”
Li Mu is stupid.
Damn, I saw the criminal investigation clip in the movie before. It takes time for the police to locate the criminal suspect. In many cases, the time for the criminal suspect is just right. When the police are about to locate him, they just hang up the phone. I thought these were just exaggerations of the movie works, but I didn't expect that they were really so troublesome!
Li Mu asked again, ”if at 12 o'clock tomorrow, the call time of the other party can't meet your needs, you still can't locate a specific location, right?”
The other party nodded: ”we can locate a radius range, but the radius may be very large. If the signal base station is not dense enough in the suburbs, the range will be even larger...”
Li Muza smacked his lips and said, ”now check song Zhilei's cell phone number and see what his cell phone is!”
At present, most mobile phone numbers do not have real name system, but song Zhilei's common mobile phone tail number is four 8 leopard numbers. This number is obtained from the mobile operator's relationship, so there is real name certification. The technical personnel from the operator began to thoroughly check the roaming situation of this mobile phone number at the first time.
However, the result of the survey was particularly disappointing: ”Mr. Li, the last time the mobile phone was put into the Internet was five days ago, the place of access was in Shanghai, and then it lost the audio. It should be that the device has been turned off, and it has not been turned on until now.”
”Check if there are any other cell phone numbers under song Zhilei's name?”
”One of them was shut down five days ago!”
”And his family?”
”I found out his wife, and his cell phone was turned off five days ago!”
There were many difficulties. Li Mu was a little nervous and desperate.I know song Zhilei did it, but where can I find song Zhilei? Time is pressing. The longer it is delayed, the more dangerous Wei Lan will be.
The criminal investigation team of the Municipal Bureau has started to lay out the simple clothes from WANYING real estate. At present, Li Mu has only two dependencies:
first, the criminal investigation team should find the first scene as soon as possible and follow the lead to find valuable clues;
Second, at noon tomorrow, when the bandits call for confirmation, let the operators' technicians locate the base station. Hope Can locate each other's position!
……
PS: five thousand words, this is the first watch. Tonight, we will strive for the third watch and work together! Ask for a monthly ticket!!!