Mobile phone detection technology mainly detects when the electromagnetic wave signal emitted by the mobile phone when it is working causes the electromagnetic power in the area where the mobile phone is to increase to a set value, thereby determining that a mobile phone is working. This technology sounds very advanced at first, but in fact it is just a very superficial understanding. When this technology was proposed, the following issues were not considered:
1. Uncertainty of mobile phone transmit power
The specific base station through which a mobile phone enters the network when working is determined by the traffic volume and dynamic deployment of surrounding base stations. When the mobile phone is logged in and used, if the nearby base station is busy, it will log in to the idle base station farther away. The transmit power of the mobile phone will be adjusted accordingly according to the link loss of the mobile phone to the base station radio wave. Usually, the mobile phone receives the signal from the base station. The stronger the signal, the weaker the transmit power.
2. The distance between the mobile phone and the detector (link loss) is uncertain
The distance between the mobile phone and the detector and whether there are any obstacles in the middle will affect the strength of the signal received by the detector.
3. The intensity of space electromagnetic interference is uncertain
Common lightning, fluorescent lamps, electronic equipment, etc. are all sources of interference. At the same time, when mobile phones are working, there is a lot of out-of-band stray noise. Although the surface acoustic filter used in the detector is used on mobile phones, the filter has insufficient out-of-band suppression and is prone to cross-frequency phenomena. When used for detection, it cannot effectively filter out other interference signals, causing the detection system to be in chaos.
4. Detector setting sensitivity is uncertain
Generally, the sensitivity setting of a detector does not have a specific quantitative value. During debugging, adjust the sensitivity by constantly adjusting the position and dialing the mobile phone to observe whether the detector detects it.
