In college entrance examination halls, phone blockers are widely used to ensure the fairness and seriousness of the examination. This device can not only effectively prevent students from cheating with mobile phones, but also create a quiet and interference-free examination environment. The cell phone jammer blocks mobile phone signals inside and outside the examination hall to ensure that candidates concentrate on the examination process and prevent external information from interfering with the examination.
Mobile phone signal blockers are devices used to block mobile phone signals. They are mainly used in examination halls, schools, gas stations, churches, courts, libraries, conference centers, theaters, hospitals, government agencies, financial institutions, prisons, public security, military bases and other places where mobile phones are prohibited. In these occasions, mobile phone signal blockers can effectively prevent signal "invasion" and ensure the purity and safety of the environment.
The technical characteristics of phone blockers are mainly reflected in their frequency range and interference methods. At present, the mobile phone signal jammers on the market can block mobile phone signals with a radius greater than 20 meters. The shielding radius is adjustable and the coverage range can reach 200 square meters. The mobile phone signal jammer works in the CDMA800, GSM900, DCS1800, and PCS1900 frequency bands. The jammer can control a range of about 40 meters in diameter, using a DC-DC converter input voltage and an output voltage of 5V. Its working principle is to quickly scan within these frequency bands to generate interference signals to prevent the mobile phone from establishing a connection with the base station. This technology can not only effectively shield mobile phone signals, but also will not affect other electronic devices, ensuring the normal operation of other equipment in the examination room.
When the mobile phone is working, it relies on radio waves within a certain frequency range to connect with the base station, complete data and interfere with part of the frequency range, blocking the communication between the mobile phone and the base station. Specifically, during the working process, the jammer scans from the low-end frequency of the forward channel to the high-end at a certain speed. This scanning speed can form garbled interference when the mobile phone receives the SMS signal, so that the mobile phone cannot detect the normal data sent by the base station, and thus cannot establish a connection with the base station. The mobile phone appears to search for the network, no signal or no service system.
