The Role of Cell Phone Jammers in Ensuring Fairness in National College Entrance Examinations

Maintaining the Integrity of the Gaokao

The Use of Cell Phone Jammers:

Cell phone jammers are employed during the National College Entrance Examination to prevent cheating and the use of electronic communication devices. Initially, students were perceived as potentially dishonest individuals who might resort to cheating during the Gaokao. As a result, examination centers introduced cell phone jammers to eliminate any possibility of cheating through electronic means.

The Functionality of Cell Phone Jammers:

To isolate a classroom or examination center from electronic communication, it is possible to employ electromagnetic shielding. Since various communication tools rely on electromagnetic or radio waves to transmit signals, the use of electromagnetic shielding, similar to a Faraday cage, can effectively achieve this goal. By enclosing the classroom with a shield, all electromagnetic signals emitted by mobile phones within the room are absorbed by the walls. However, implementing such shielding in regular classrooms is not feasible.

Previous Cell Phone Jammers:

The cell phone jammers used in previous Gaokao examinations were not the same as the aforementioned shielding devices. The current cell phone jammers used during the Gaokao operate by emitting disruptive signals when a mobile phone attempts to send or receive messages. These disruptive signals overwhelm the phone, rendering it unable to transmit or receive information effectively. In other words, the cell phone jammer does not completely block the signal, as this would require stringent conditions. Instead, it floods the signal with noise, making it indistinguishable among the multitude of useless signals. This can be likened to trying to have a private conversation with your girlfriend while 20 foreigners simultaneously rap in 20 different languages, making it impossible to hear her.

Effects of Cell Phone Jammers:

The use of cell phone jammers not only blocks signals within the examination center but also interferes with wireless signals in the surrounding area, significantly affecting the call quality of nearby mobile phone users. Therefore, it is essential for everyone to exercise patience and understanding for the sake of the nation’s students during the three-day examination period.

Limitations of Cell Phone Jammers:

The entire electromagnetic spectrum ranges from a few Hz to several tens or hundreds of GHz, encompassing a wide range of frequencies that can be used for communication. However, ordinary cell phone jammers have limited capabilities and can only block a small portion of the frequency bands. Communication devices can still utilize the unblocked frequency bands for communication. Nevertheless, the cell phone jammers used in examination centers can concentrate their efforts on the specific frequency bands used by several domestic telecommunication companies for 2G, 3G, and 4G services.

Alternative Cheating Methods:

Despite the effectiveness of cell phone jammers in preventing cheating through mobile phones, individuals attempting to cheat can still use their own communication tools. For instance, some cheaters possess wireless transmitters, while others have wireless receivers disguised as everyday objects. These illegal communication tools often operate on frequency bands beyond the reach of cell phone jammers, frequently encroaching upon those designated for walkie-talkies.

The Role of Wireless Monitoring Devices:

To counteract these alternative cheating methods, wireless monitoring devices can detect electromagnetic signals in frequency bands that cell phone jammers may overlook. Before the examination begins, the signal strengths generated by legitimate wireless devices such as mobile phones, radios, and televisions in the vicinity of the examination center are recorded. Once the examination commences, wireless monitoring devices are activated in vehicles, briefcases, and offices, enabling the detection of any unidentified electromagnetic signals. Cheating devices are unlikely to evade the scrutiny of these sophisticated monitoring devices.


The installation and use of cell phone jammers during the National College Entrance Examination are essential to maintain the integrity of the examination process and ensure fairness for all students. While these devices may have limitations, they play a crucial role in preventing cheating through mobile phones. Additionally, the implementation of wireless monitoring devices further enhances the examination’s integrity by detecting any attempts to cheat using alternative communication tools. By employing these measures, the Gaokao continues to uphold its reputation as a fair and unbiased assessment of students’ abilities.