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On the annual college entrance examination, some 4S stores will suddenly send a message, they reminded that the signal interference car used by the recent test center may affect the car signal, causing the car door to fail to start or to open the car door. The solution is to use the mechanical key to open the door. .

This situation is actually a "special situation" during the college entrance examination. In order to shield high-tech cheating tools, electronic devices such as signal jammer vehicles will be set up near the test center. These electronic devices can also cause signal interference to vehicles that are driving or parked in the surrounding area, which may result in the failure of the smart key.

Why does the key fail? First of all, we need to understand the characteristics of the signal jamming car.

(1) All frequencies between 20-6000MHz can be shielded, and the frequency can be adjusted at any time to avoid the police law enforcement frequency.
(2) The signal jamming vehicle is equipped with a special power generation system/control system, and the rear seat is reserved, which does not occupy space, and does not generate exhaust gas and noise.
(3) The roof antenna adopts an electric lodging mechanism to achieve rapid lifting. When the signal jamming vehicle performs its task, it can be interspersed with the VIP or leader convoy under the condition of supporting a speed of 100 kilometers per hour to prevent the robbers from detonating the remote control bomb. If the signal jamming vehicle does not perform tasks, the antenna can be lowered and hidden to facilitate other tasks.
(4) The modular plug-in design provides convenience for the frequency and power rise and fall of the signal jamming vehicle in the later stage, and at the same time facilitates daily maintenance and repair.
(5) The signal jamming vehicle is fully equipped with a DDS module. The output power and frequency band of the module can be changed through the computer main control software, and a special communication frequency band can be set in an emergency.
From the above characteristics, we can see that the signal jamming car can continuously shield all frequencies between 20-6000MHz. The frequency used by the car remote control key is also within this range. Therefore, when the signal interferes with the opening of the car, the car remote control key will be disturbed.
However, there is absolutely no need to worry about that. When the smart car key is disturbed, malfunctioning or insensitive, please don't worry. If this happens, please use the mechanical key to open the car door, and place the remote control key near the one-key start switch (at this time the key distance After starting the sensor recently), step on the brake normally, and then press the ignition switch, the vehicle can start normally;
There will be a delay in the positioning of the vehicle navigation system, and the radio cannot receive the station temporarily. Please don't worry, when the vehicle drives out of the interference signal, everything can return to normal.

Therefore, the effective shielding range of the jammer mainly depends on the following points:

1. The power of the signal jammer. Now there are many signal jammers on the market that are said to be 5W, but the actual power is less than 1W. Therefore, it must be the actual power. For low-power signal jammers within 1W, the shielding distance is about 1-10 meters, and the shielding range is 10-30 square meters. But what needs to be understood is that such a signal jammer cannot penetrate walls.

2. The density of nearby base stations. Now many customers buy back signal jammers, 2G and 3G calls can be blocked, but 4G calls cannot be blocked. What is the reason? It is because there are base stations near you. Generally speaking, if there is a base station within 100 meters, buying a low-power signal jammer will basically not work, because the signal strength of the base station is too strong. It is recommended to buy a jammer with a medium power, with a ratio of more than 2W per channel.

3. Field wall environment. What is the field wall environment? It is the place where the shield is installed, whether it is a cement wall or a glass partition. Ordinary shields have no effect through walls.

Based on the above, the shielding range of the mobile phone signal jammer is not determined by a single factor. It is recommended that before buying in large quantities, the best way is to use a field wall meter to test the signal strength of your installation environment.