This may be a problem that many people will consider when buying signal jammers.

For example, the radio we usually listen to is fm88.3, which tells us the frequency of your city. Then, I can also get one with the same frequency, but my frequency, which has not been reported to the local Radio Regulatory Commission, is illegal. To interfere with your normal radio frequency. For example, the interference radius of the high-power Signal Jammer used in the prison can reach several hundred meters, while the interference radius of the small-power jammer suitable for the examination room and the conference room is generally between 1 and 10 meters, depending on the strength of the nearby signal base station.

The high-power Jammer (several hundred w or even more than 1000 W) has very strong interference ability and is suitable for special occasions such as prisons and detention centers. However, because of its strong interference ability, if it is close to the residential area, it will inevitably affect the normal mobile phone call demand of the nearby people. Therefore, high-power signal jammers are generally used in relatively open places far from residential areas.

The interference radius of the small power Jammer (generally 12w-20w) is between 1-10m. The instructions of some products claim that it is between 1-20m and 1-30m. In fact, the upper limit is difficult to reach.

This is because the effect of the Signal Jammer mainly depends on the signal strength at the place of use. Assuming that multiple signal base stations are set up in the campus of a school, and the receiving level of mobile phones is ≥ - 70dBm, the actual interference of the jammer will be greatly reduced, and may only interfere with the distance of 2 or 3 meters. If there is no base station in the campus and the receiving level of mobile phones is ≥ - 90dbm, the jamming effect of the Signal Jammer will be very good. There is no problem with the distance of 10m. It is enough to put a jammer in one examination room.