First, the detection of an open mobile phone is realized by using a miniature high-frequency radio receiver. The working frequency of mobile communication (I don't mean China Mobile Communication Company) is generally 7450KHZ to 8 100KHZ. As long as the mobile phone is in standby state, it will send some radio instructions to the relay station (local station) from time to time, whether it is used for daily use or not.

When the mobile phone is just turned on: send the power-on status or accept the signal normal or network confirmation instruction;

When the mobile phone is on standby, it will send identity information and location information intermittently;

The mobile phone will send a confirmation command when the region changes;

When a mobile phone is in use, it must transmit signals at the same time when talking, searching for signals or network or information. ;

When the mobile phone is turned off, a power-off confirmation instruction is sent before the power-off is completed;

All signals sent by mobile phones will be received by receiving devices. If the mobile phone in use is not detected,

It can only be well shielded by metal, and it is best to put it in a multi-layer iron container, but the final result of the mobile phone still cannot be used.

explorer

Detector is a device for observing and recording particles, and it is an indispensable equipment in the experimental research of nuclear physics and particle physics. Detectors can be divided into two categories: counters and orbital detectors. The metal detector uses the principle of electromagnetic induction to generate a rapidly changing magnetic field by using a coil with alternating current.