With the rapid advancement of technology, mobile phones have become an indispensable tool in our daily lives, providing great convenience. However, the misuse of mobile phones for cheating during various national examinations has become a growing concern in recent years, severely impacting the discipline within examination halls. To address this issue, the government has mandated the use of full band interference devices in standardized examination venues during important test periods, aiming to create a fair and unbiased examination environment. Nevertheless, some instances have been observed where certain examination halls equipped with interference devices still display mobile phone signals. This article aims to explore the reasons behind this phenomenon and shed light on the effectiveness of full band interference devices in different examination settings.

Mobile Phone Signals Despite Interference Devices

Despite the presence of full band interference devices, some mobile phones still display signals in certain examination halls. There are several possible explanations for this occurrence.

  1. Ineffective Shielding: If a mobile phone displays a signal and can make clear calls without any disruption, it indicates that the full band interference device in use has not effectively shielded the area. This could be due to the presence of a nearby base station or an indoor signal amplifier. In such cases, it is recommended to install additional high-power interference devices to meet the required level of signal blocking.
  2. Unstable Signal Blocking: When a mobile phone shows a signal but experiences poor call quality, it suggests that the full band interference device is operating at its critical state of signal blocking. While there is some level of interference, the range of blocking may be unstable. This instability could be attributed to fluctuations in signal strength from the base station to the examination venue or the use of mobile phones with strong anti-interference capabilities.

False Signals and Their Interpretation

In certain instances, mobile phones may display signals that are actually false, indicating successful interference by the full band interference devices. These false signals can be identified through the following observations:

  1. No Call Connectivity or Data Access: When a mobile phone displays a signal but cannot make calls or access the internet, and suddenly shows no signal or limited service upon dialing, it can be concluded that the displayed signal is false. In reality, the mobile phone is being effectively blocked by the interference device.
  2. Range of Signal Blocking: The range of signal blocking by full band interference devices depends on the strength of mobile phone signals in the location where the device is being used. In areas with strong mobile phone signals, the blocking distance of the interference device will be shorter. Conversely, in areas with weak mobile phone signals, the blocking distance will be greater.


The use of full band interference devices in examination halls is a crucial step towards maintaining the integrity and fairness of national examinations. However, it is essential to ensure the effectiveness of these devices by considering factors such as signal strength, location, and the presence of signal amplifiers. By addressing these considerations, examination authorities can enhance the reliability of full band interference devices and create a truly fair examination environment.