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The principle and use of mobile phone signal jammer

The principle and use of mobile phone signal jammer


signal jammer

Basic Information

        When the mobile phone is working, it is within a certain frequency range. The mobile phone and the base station are connected by radio waves to complete the transmission of data and sound with a certain baud rate and modulation method.

        The common mobile phone signal jammers on the market have the following frequencies: 869-894MHz; 925-960MHz; 1805-1880MHz and 1900-1990MHz, etc. The working frequency bands are CDMA800, GSM900, DCS1800, and PCS1900. It can control the range of about 40 meters in diameter, using DC-DC converter input voltage, 5V output voltage.

        After the listing of 3G signals, the working frequency bands of the mobile phone signal jammers on the market today have also been upgraded from the previous four frequency bands to five frequency bands. On the basis of the previous four frequency bands, the frequency band of 2100 to 2200 has been added. It is used for shielding and interfere with the 3G band.

        In today's information age, the development of communication technology is changing with each passing day. As a unique talent in the communication family, mobile communication plays an important role in people's life, industrial and agricultural production and other fields. At the same time of great convenience, there are also some problems that cannot be ignored. Due to the wide coverage of mobile communication networks, in some occasions, the use of mobile phones has brought trouble to people and even caused security risks. The noise pollution source interferes with the normal work order; 3 becomes a new unsafe factor, which brings hidden dangers to the safety production of enterprises; 4 becomes a new crime method, which has an impact on social stability, so in some places we should be able to artificially destroy it. Or limit this kind of network to avoid the harm caused by the mobile network, so the mobile phone signal jammer came into being.

        The mobile phone signal jammer, in essence, implements electromagnetic interference on the wireless network on which mobile phone communication depends, so that the mobile phone cannot be connected to the Internet, and thus cannot receive information from the mobile network, and cannot send information through the network. But it has no effect on the signal generated by the phone.


        The cell phone jammer scans from the low-end frequency of the forward channel to the high-end frequency at a certain speed during the working process. The scanning speed can cause garbled interference in the message signal received by the mobile phone, and the mobile phone cannot detect the normal data sent from the base station, so that the mobile phone cannot establish a connection with the base station. The mobile phone is manifested as searching the network, no signal on the mobile phone, no service system, etc.

        The mobile communication network consists of a mobile service switching center MSC and each base station BS under its control. Each base station includes a receiver and a transmitter. Although the radio signal transmitted by the base station covers a circle on the ground, considering the entire network. The effectiveness and connection of coverage, so the actual scope of each base station is a regular hexagon centered on the base station, also called a cell. The total coverage of all base stations is equivalent to the overall arrangement of adjacent regular hexagons.

        Therefore, mobile communication is also called cellular mobile communication. As far as the mobile phone in each cell is concerned, it communicates with the base station through the uplink frequency of the channel, and then transfers the signal to the MSC to communicate with other mobile phones or fixed phones. The radio frequencies received by the mobile phone are divided by frequency band.

        GSM segment 925-960MHz, DCS segment 1805-1880MHz, CDMA segment 869-894MHz, PHS 1900-1990MHz, SCDMA 450- 470MHz, WCDMA 2110-2170MHz, TD-SCDMA 2010- 2025MHz. Each frequency band is divided into many channels with a certain bandwidth. Each cell uses several channels, one of which is called the broadcast control channel, represented by BCH, and the other channels are called the traffic channel. In the standby state, the mobile phone starts the receiving circuit intermittently to receive the BCH in the cell where it is located. According to the field strength of the BCH signal, the signal bar is used to display the signal strength indicator RSSI on the LCD. When making an outgoing call, the first step is to ask the MSC for instructions through the BCH, and the MSC handles the calling or the called party. The MSC assigns a service channel to the mobile phone according to the channel status in the cell, so that the mobile phone jumps from the BCH to the service channel to realize the call. It can be seen from this that the BCH in the community is the medium and advance condition for realizing mobile phone communication. If the mobile phone cannot find the BCH in the community, there will be no network name and signal strength indication on the light screen LCD, that is, the mobile phone will be in no network, no In the state of network access, the mobile phone cannot realize the function of calling or called, that is, the mobile phone signal is equivalent to being blocked.

        It can be seen from the above analysis that if there is no network in a certain area within the coverage area of the mobile network signal and the mobile phone cannot access the network, the BCH manpower in the area should be destroyed. If the frequency is artificially transmitted in this specific area If the signal has the same downlink frequency as the BCH in the cell, and the signal field is stronger than that of BCH, the mobile phone in the area cannot receive the BCH signal, so that the mobile phone in the area cannot access the network. The mobile phone signal jammer is manufactured according to this principle of.

        Since there are many channels in any frequency band of mobile communication, and each channel can be used as BCH, which channel is used as BCH in a cell is completely determined by MSC according to the distribution of channels in the entire network. Generally, in order to prevent mutual crosstalk between channels with similar frequencies, the frequencies between channels in the same cell should be quite different. The same channel and adjacent channels cannot be used within a cell. Among the several channels allocated in each cell, one of the channels is designated as BCH, and the rest are traffic channels. Due to the non-fixation of BCH, the situation where the masker is used is different. In addition, there may be more than two BCHs under the network in the adjacent area of the cell. Therefore, when using the signal masker for interference, it should be used in this area. It can interfere with all channels of the mobile communication network that may appear in the network, that is, all frequency signals in the GSM, DCS, PHS, CDMA, SCDMA, WCDMA, TDS-CDMA frequency bands should be transmitted, so as to achieve interference to all mobile phone signals. The shielding of the signal received by the mobile phone is realized, and the connection between the mobile phone and the base station is cut off.

        In order for the mobile phone signal jammer to interfere with the mobile network, it must be ensured that the signal field strength emitted by the jammer should be great.

        Because of the field strength of the mobile signal BCH in the interference area, the size of the effective area of the interference is different in different locations where the same jammer is used. Generally, the closer to the base station, the stronger the field strength of the local BCH, and the smaller the area where the scrambler can achieve effective interference. Generally, the interference radius can only reach a few tenths of a meter to a few meters; The radius of the jammer to achieve effective interference is larger, which can reach more than ten meters to several tens of meters. Therefore, the size of the local BCH field strength should be fully considered before using the jammer, and then the position, quantity and combination of the jammer should be determined according to the size of the interference area. The relationship between the signal field strength E sent by the base station and the jammer interference radius r The curve is shown in the figure:

cell phone jammer

        Obviously, the farther the jammer is from the base station, the weaker the field strength and the larger the interference radius, and vice versa. The jammer loses its jamming ability if it is too close to the base station.

        When the same shield is used outdoors, the interference range will be doubled compared to when it is used indoors. If the interference range is within 200m”, generally a shield can be installed and hung in the middle of the indoor wall, 1~1.8 meters away from the ground; if it is greater than 200m3 , Generally, two or more sets should be set up and placed on the front and rear walls; if the interference space is outdoors and larger than 10o0m, multiple sets should be used, and the effect of cellular distribution is better.

        Since the frequency band used by the mobile phone is dedicated, the transmission frequency of the mobile phone signal jammer completely falls within the working frequency band of the mobile phone stipulated by the state, so it has no effect on other electronic equipment such as TV and radio, and the mobile phone jammer only interferes with the transmission of the base station received by the mobile phone. The BCH sent out makes the mobile phone unable to establish contact with the base station, so it does not have any effect on the mobile phone, and the signal field strength it sends out is stronger than BCH, but through testing, it is far stronger than the electromagnetic radiation field strength generated when the mobile phone is talking It is much weaker, so it will not cause harm to the human body and can be used for a long time with confidence.

        It is worth noting that the anti-interference ability of CDMA mobile phones is much stronger than that of GSM mobile phones, so the effective shielding distance of mobile phone signal blockers for CDMA mobile phones is smaller, but the difference is not about 2~4 meters, so in some particularly important places , If necessary, the number of mobile phone signal jammers in the interference area should be increased to ensure the shielding effect of CDMA mobile phones.


        Introduction to the Principles of Mobile Communication,the working principle of the mobile phone is as follows: within a certain frequency range, the mobile phone and the base station are connected by radio waves to complete the transmission of data and sound with a certain baud rate and modulation method.

        Introduction to the principle of mobile phone signal jammer (shielding device), according to the above communication principle, the jammer scans from the low-end frequency of the forward channel to the high-end frequency at a certain speed during the working process. The scanning speed can cause garbled interference in the message signal received by the mobile phone, and the mobile phone cannot detect the normal data sent from the base station, so that the mobile phone cannot establish a connection with the base station. The mobile phone manifests as the phenomenon of searching the network, no signal, no service system, etc.

Scope of application

        Cell phone signal jammer is also known as: jammer, cell phone jammer, signal jammer, cell phone signal jammer, cell phone signal blocker, cell phone isolator, cell phone cutoff, mobile communication signal jammer, cell phone signal jammer, cell phone jammer device, signal jammer, cell phone blocker, signal blocker, cell phone signal isolator, signal isolator, cell phone signal blocker, radio signal blocker.

        It uses frequency multiplication, frequency division, frequency hopping filtering and other technologies to analyze the required shielding frequency for the uplink and downlink channels of the mobile phone system; customizes a spherical shielding space according to the power of the shield, and automatically forms a shielding magnetic field within the specified range. Make mobile phones (including PHS- PHS-GSM-China Unicom, China Mobile, CDMA-China Telecom) disabled in this space. When the jammer is in working state, it can disable the function of sending and receiving signals of mobile phones within a specified range, and cannot dial out or dial in, so as to achieve the purpose of mandatory disabling.

        Can be used in: various examination rooms, conference rooms, gas stations, oil depots, churches, hospitals, courts, military centers, libraries, theaters and other places. However, in densely populated areas such as schools, it is forbidden to set up radio stations with excessive electromagnetic radiation, and mobile phone signal jammers are not allowed to be used without authorization.

The management method of mobile phone blocker

        The use and management of mobile phone jammers involves the business scope of two departments: radio management and confidentiality management. The two departments should issue a normative document as soon as possible on the basis of full consultation, which can not only ensure the security of secret information but also meet the technical requirements of national radio transmission equipment. Standardize the development, production, sales and use of mobile phone jammer equipment. Better safeguard the interests of national information security, safeguard the order of national communications, and safeguard the rights and interests of the masses in communications consumption.

        Guangdong Amplitec Tech Development Co.,Ltd is a professional mobile phone signal jammer manufacturer, providing outdoor signal shielding solutions and outdoor large-scale engineering shielding solutions free of charge.

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