With the continuous development and popularization of mobile phones as a mobile communication tool, and the continuous improvement of the technical level of mobile communication tools, especially the promotion and application of 3G and 4G technologies, its negative effects on prisons, labor camps, detention centers, drug rehabilitation centers, and other similar fields. The influence is becoming more and more prominent. In prisons, detention centers, and other places of supervision, mobile communication tools, such as cell phones, are expressly prohibited, not only to prisoners but also to supervisors. Once the mobile phone is brought into the prison and put into use, it will bring great harm to the development of prison management. Some prisoners call, send text messages, obtain information, threaten witnesses through the illegal smuggling of mobile phones, and even form gangs to escape from prison. To this end, the installation of wifi jammer-blocking systems in prisons and other prison premises is imminent.
At present, the power and channel of each base station are different, and the distance between each base station and the prison is also different. It is generally recommended that a base station is not required within 200 meters or 300 meters of the surveillance area where the wifi signal jammer is installed. If there is a base station, it is necessary to consider the impact of strong signals on the base station.
Influence from various building layouts in prisons， Dimensions of each prison, number of buildings, structure, dimensions, the height of floors, etc. All are different. The distribution direction, power, terrain, and other factors of mobile phone base stations around each prison are different, and the signal strength transmitted from the remote base stations is also different. How to distribute the sites of each prison needs to be designed according to the actual site conditions.
Even in the same environment, the base station signal can be affected by wind interference, air humidity, etc. This will also cause fluctuations in the signal field strength. In addition, there are differences in the field strength between indoors and outdoors. Ground building structures and metal objects have very complex adverse effects on shielded signals