Signal shielding is required in many places, but many people don't know how to install a cell phone signal jammer. Some people believe that signal jammers can be connected directly to the mains, while others believe that the frequency needs to be adjusted. It's hard to tell if a cell phone jammer is working, so let's look at how signal blocker works.

1. Adjacent channel interference.

Adjacent channel interference refers to signal interference at frequencies adjacent to the signal frequency used. Adjacent frequency interference is caused by ideal connections, causing signals at adjacent frequencies to leak into the transmission bandwidth.

2. Near and far effect.

This problem becomes very serious if the base station of the adjacent channel transmits within a very close range of the user receiver, and the receiver uses the base station signal of the preset channel, which is called the near-far effect.

3. Intermodulation interference.

When two or more signals of different frequencies act on a nonlinear circuit, the signal outputs of the new frequencies will modulate each other. If the frequency falls exactly within the bandwidth of the receiver's working channel, it will cause interference to the receiver and become intermodulation interference.

4. Blockage and interference.

Any receiver has a certain dynamic range of reception. When the interference signal outside the frequency band is strong enough and the received power exceeds the maximum power level promised by the receiving dynamics, the receiver will be completely blocked, thus affecting the receiving function of the system. This interference is called blocking interference. Blockage will prevent the receiver from functioning properly, and long-term blockage may cause the receiver to degrade.

5. Spurious interference.

Due to the roll-off characteristics of the emission filter, there will always be a certain amount of out-of-band radiation, which is what we usually call emission spurious. Spurious interference due to emission is called spurious interference.

Interference between mobile communication systems.

1. Intra-interference: The CDMA transmitted signal acts on the GSM receiver as in-band noise directly or through intermodulation, etc., thus reducing the sensitivity of the GSM receiver. This interference is further divided into emission spurious interference and intermodulation interference;

2. Out-of-band interference: When the out-of-band interference reaches a certain level, it will cause the receiver to be completely blocked, thus affecting the receiving function of the GSM system. This kind of interference is also called blocking interference.

The use of cell phone signal jammers makes our lives easier, but its signals are susceptible to interference, so we still need to adjust its frequency.