WO2020024602A1

WO2020024602A1 - Gsm mobile phone signal blocking method and system

Info

Publication number: WO2020024602A1
Application number: PCT/CN2019/080323
Authority: WO
Inventors: 曹永福; 张宏亮; 邵雪平; 周亚良
Original assignee: 浙江三维通信科技有限公司
Priority date: 2018-07-26
Filing date: 2019-03-29
Publication date: 2020-02-06
Also published as: CN108737015B; CN108737015A

Abstract

Disclosed are a GSM mobile phone signal blocking method and system. Blocking is achieved by interfering with an uplink frequency of a mobile phone. The method comprises: by using a characteristic that an uplink signal transmitted by a mobile phone has at least one uplink time slot time period, detecting and identifying, within the uplink time slot time period, whether the strength of the uplink signal has reached a set level threshold, and accordingly determining whether the transmitting mobile phone is located within a shielded region; and if it is determined that the mobile phone is located within the shielded region, transmitting a blocking interference signal in the same time slot, and causing the strength of the interference signal to be greater than the strength of the uplink signal transmitted by the mobile phone, so as to interfere with receiving performed by a base station, such that communication of the mobile phone is interrupted. A GSM mobile phone signal blocking system comprises an uplink receiving antenna, a filter, a power detection comparator, an interference transmitter, and an uplink interference antenna. Using the method and system of the invention to block a GSM mobile phone signal does not affect other users in a region, and transmission is not performed when no mobile phone is in use, thereby reducing wastage and wireless signal pollution.

Description

Method and system for shielding GSM mobile phone signal

Technical field

The invention relates to the shielding field of mobile communication, and mainly relates to a shielding method and system for a GSM mobile phone signal.

Background technique

For the shielding of GSM mobile phones, most of them use the interference downstream frequency to achieve shielding. Common examples are frequency sweeping shields, white noise interference shields, frequency sweeping shields or white noise interference shields and fixed frequency types. A combined fixed-frequency type jammer formed by the combination of jammers. When targeting strong base station signals, it is usually to select several frequency points to strengthen interference at the strongest nearby base stations, that is, N-point frequency type interference. Take the signal of the same frequency band as an example. There are two operators' base stations. For example, one operator's base station is close and the signal is strong, and the other operator's base station is far away and the signal is weak. For a base station with a weak signal, because the shielding is set according to the strongest base station, the shielding at this time is too strong for a weak signal base station, that is, the shielding area is large, resulting in a weak signal. The shielding area covered by the base station operator exceeds the requirements, causing communication difficulties for users outside the requirements of the shielding area, which leads to user complaints.

The patent with publication number CN103607254B discloses a self-interference shield, which is applicable to mobile phones of various standards including GSM. The technology adopted is: a local transceiver antenna receives and stores the downlink air signal, and sends the signal in accordance with certain rules. Signal and make it larger than the original signal to achieve effective shielding. However, this technology has the following problems: In view of the characteristics of GSM, the BCCH carrier is continuously transmitted, and the TCH carrier is transmitted on demand. Therefore, the shielding of the BCCH carrier by this patented technology is complete. It is not guaranteed that the TCH carrier can obtain the user transmission time slot, that is, the shield is normal when the TCH carrier is received and transmitted, and when the TCH carrier is not transmitted, the shield is not transmitted. At this time, the shield is not transmitted because the TCH carrier does not transmit. The shielding of the carrier is invalid, so the shielding of the TCH carrier is missing.

Summary of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art, and to shield the GSM mobile phone signal by implementing interference on the uplink signal of the GSM mobile phone. Since there is no downlink signal interference, a clean shielding area can be achieved without affecting other users; In addition, when no mobile phone is used, it will not transmit, reducing waste and reducing wireless signal pollution.

The object of the present invention is achieved by the following technical solutions. A method for shielding a GSM mobile phone signal. The method includes the following steps:

(1) Monitor all uplink frequencies in the shielded area and capture the uplink signals of the GSM mobile phone;

(2) Utilize the characteristic that the uplink signal transmitted by the mobile phone has at least one uplink time slot period, and detect and identify whether the uplink signal strength reaches the set power level threshold during the uplink time slot period, and determine whether the transmitting mobile phone is based on this Located in a shielded area;

(3) For a mobile phone determined to be located in a shielded area, a shielded interference signal of a simultaneous slot is transmitted, so that the strength of the interference signal is greater than the strength of the uplink signal transmitted by the mobile phone to interfere with the reception of the base station, thereby interrupting the communication of the mobile phone.

Most of the existing technologies use the interference of the downlink frequency of the GSM mobile phone to achieve shielding, and the present invention subverts the interference of the uplink frequency of the GSM mobile phone to achieve the purpose of shielding. Since the interference is directed to a single mobile phone, only when it detects that there is a GSM mobile phone transmitting in the shielding area, the shielding interference of the simultaneous slot is transmitted. By using the feature that the uplink signal transmitted by the mobile phone has at least one uplink time slot period, since the power of the GSM uplink time slot is basically constant throughout the length of the time slot, it is only necessary to detect the power of the previous part of the time slot. Think of it as the power level of the time slot, and identify whether the mobile phone is located in the shielded area based on this. For the mobile phone that is determined to be in the shielded area, the time slot interference is transmitted during the remaining time of the time slot to interfere with the base station reception. So as to achieve the purpose of shielding mobile phones. Since the GSM base station allocates independent uplink time slots for each mobile phone user, as far as the GSM base station is concerned, the interference implemented by the present invention during the uplink time slot period will not affect the normal communication of other mobile phone users. The invention realizes no unnecessary emission and effectively reduces energy waste and pollution.

It should also be noted that the traditional shielding technology mostly uses the method of shielding the downlink signal to shield the GSM mobile phone. For the base station using the radio frequency hopping technology, it is necessary to shield all TCH carriers participating in frequency hopping at the same time, and the TCH carrier participating Frequency hopping has a large number of frequency points, generally as many as 10 or more, so it needs to consume a lot of power. The technology provided by the present invention is not affected by this. Because this technology monitors all uplink signals in the entire shielded area, the system can implement capture regardless of whether the base station uses radio frequency hopping technology. For radio frequency hopping, this technology is only related to the number of real-time time slots transmitted by mobile phone users in the shielded area. For example, if two time slots are transmitted at the same time, only the frequency points corresponding to these two time slots are sent. The next time slot can track the other two frequency points corresponding to the respective frequency hopping sequences in real time according to the detection of the mobile phone's transmission signal, but the number of required transmission frequency points is still two, that is, two real-time TCH carriers, so there is no need to consume a lot of Power, reducing energy waste and communication interference to normal users.

The present invention can be further defined and improved by the following technical solutions:

As a technical solution, before transmitting the shielding interference signal of the time slot, it is necessary to discriminate the uplink signal transmitted by the mobile phone from other shielding interference signals in the shielding area; if the mobile phone signal is determined, further detect and identify the strength of the uplink signal. Whether the set power level threshold is reached; if it is judged to be other shielding interference signals, the next action is suspended. For a large shielding range, it is usually necessary to arrange multiple shields in the shielded area so that the entire area has a good shielding effect. Therefore, the uplink signals transmitted by mobile phones in the shielded area and other shields in the shielded area need to be arranged. The transmitted interference signals are screened. If it is judged to be a mobile phone signal, further shield interference signals of the time slot will be transmitted; if it is judged to be other shield interference signals, the next shield emission will be stopped.

As a technical solution, the uplink time slot period transmitted by the mobile phone includes an identification detection period and a shielding transmission period; the identification detection period is used to detect whether the strength of the uplink signal reaches a set power level threshold, If the strength exceeds the set power level threshold, the shielding interference signal of the time slot is transmitted during the shielding transmission period, and the strength of the interference signal is greater than the strength of the uplink signal transmitted by the mobile phone to interfere with the reception of the base station, thereby interrupting the communication of the mobile phone. For the case where the shielding area is small, a single shield can cover the entire shielding area, that is, there is only a single shielding transmitting signal in the entire shielding area, so there is no need to determine whether other shielding equipment has sent shielding transmitting signals. In this case, It is only necessary to determine whether it is located in a shielded area by using the uplink signal strength transmitted by the mobile phone and shield it.

As a technical solution, when there are other shielded interference signals in the shielded area, the identification and detection period is also used to distinguish the uplink signals transmitted by the mobile phone from other shielded interference signals in the shielded area, and determine the uplink signals transmitted by the mobile phone. Further check whether the uplink signal strength reaches the set power level threshold. For uplink signal strength exceeding the set level threshold, the shield interference signal of the time slot is transmitted during the shield transmission period, and the strength of the interference signal is greater than that of the mobile phone. The strength of the uplink signal to interfere with the reception of the base station, thereby interrupting the communication of the mobile phone.

As a technical solution, in the shielding area, the transmission frequencies of the shielding interference signals that are adjacent to each other are different. For multiple shields transmitting the same frequency interference signal to work together to expand the shielding area, there may be the following problems: multiple shields have detected the interference of the same mobile phone at the same time and transmitted shielding interference signals. These same frequency signals may arrive due to There is a time difference at the receiving antenna, which becomes similar in power and opposite in phase, and is superimposed on each other to cancel it out. As a result, the shielded transmission signal received by the base station is not strong enough to cause shielding failure. Therefore, when setting, the frequency of the signal transmitted by the shield should be different from that of the nearby equipment, that is, the interference signals that are transmitted are grouped. The adjacent signals are physically adjacent, and their respective interference signals have different transmission frequencies. Here, the physical neighbor refers to The installation position is adjacent. By setting it in this way, the receiver ’s anti-phase superposition at the receiver, which transmits the same frequency interference signal when the same mobile phone is detected at the same time, will cause the cancellation problem; the same can also prevent the shield Shielded emission detection and reception are cancelled out due to the inverse superposition caused by the same frequency.

As a technical solution, the uplink time slot training method is adopted: before transmitting the shielding interference signal of the time slot, the uplink time slot boundary and the time slot length of the uplink carrier of the mobile phone are obtained, and the time slot boundary includes a time slot start boundary and The time slot end boundary, the uplink time slot boundary, and the time slot length constitute an uplink time slot period. In order to accurately obtain the time slot boundary, the uplink time slot training method can be used to obtain the time slot boundary and the time slot duration of the uplink carrier of the mobile phone. The time slot boundary here includes the time slot start boundary and time slot end boundary. Specially, when there is only one mobile phone that needs to be shielded in the shielded area, the shield is not turned on, and only the uplink signal is received. After receiving one or more timeslot signals completely, the uplink timeslot boundary of the carrier is obtained, that is, After obtaining the training base station 1, after the mobile phone transmits the uplink signal again, it passes the time slot starting boundary to synchronize with the time slot training base station 1 and then starts the power level discrimination of the time slot and turns on the shield to implement interference after reaching the power level. The starting boundary of training base station 1 with non-aligned time slots is discarded. For the case that there may be multiple mobile phones that need to be shielded in the shielded area, these mobile phones may be connected to different base stations, resulting in the uplink time slot of these mobile phones. The boundaries may not be completely aligned, that is, there is a certain offset, see Figure 1 for details. For the case where the time slot boundaries are not aligned, another uplink time slot training needs to be started to obtain the time slot boundary of another base station (such as training a base station) 2) The method is the same as above, and so on, and then the same starting boundary is synchronized through synchronization before entering the next shielded emission, so that it can filter out some random radio frequency interference of the uplink frequency that is not transmitted by the mobile phone (because only the alignment has been trained (The base station 1 to the base station M can only enter the shielding discrimination start procedure for the radio frequency signal at the start time slot boundary) to reduce the impact of the shielded emission transmitted by the random radio frequency interference of the non-mobile phone's uplink frequency and the corresponding misjudgment. Reduce interference to the base station.

As an preference, in the uplink time slot training method, the mobile phones corresponding to each base station are sequentially shielded. Base station 1 is trained based on time slots, and the base station slot cycle cycle is trained by using time slots. First, all mobile phones under one base station are shielded, and then Then find the time slot training period of the mobile phone corresponding to another base station, and repeat all the mobile phones in the shielding area under all different base stations in this order. It should be noted that in general, when transmitting interference is shielded, unless the transmitting antenna is far away from the shield, the uplink receiving circuit of the mobile phone in the same frequency band has a large blocking interference; therefore, when shielding the transmitting interference, it is also considered to turn off the reception of the mobile phone's uplink signal. This results in a time discontinuity in the receiving circuit and adversely affects the reception processing, such as affecting the reading of the uplink time slot boundary during shielded transmission interference; the uplink signal transmitted between all mobile phones under a base station is The time slots are aligned, that is, after the shielded transmission is turned off, it is just the beginning of the next time slot; therefore, the present invention can shield all the mobile phones in the shielded range of the same base station without omission. The base station 1 is trained based on time slots. The present invention uses the time slots to train the base station time slot cycle. First, all mobile phones under this base station are shielded, that is, after blocking for a period of time, all mobile phones are disconnected from the network, and then received for a period of time to verify Whether the mobile phones in the shielded area are offline, that is, the mobile phone that is not aligned with the base station time slot training cycle transmits an uplink signal; then find the mobile phone corresponding to the base station time slot training cycle. Repeating this can block all All phones in the masker area under different base stations.

Preferably, the center frequency of the transmitted interference signal of the time slot is offset by a certain amount from the center frequency of the carrier signal of the GSM mobile phone. For example, the center frequency of the interference signal of the transmitted time slot is the center frequency offset of the GSM mobile phone carrier signal + 60kHz, or + 67kHz, or + 74kHz, or -60kHz, or -67kHz, or -74kHz.

Preferably, the uplink signal of the GSM mobile phone can be obtained by adding a diversity receiving antenna and a diversity receiving technology of a diversity receiving circuit. The use of diversity technology can effectively reduce the poor reception caused by the fast fading effect of the GSM uplink signal to increase the stability of the reception.

The invention also provides a GSM mobile phone signal shielding system corresponding to the above method, which mainly includes an uplink receiving antenna, a filter, a power detection comparator, an interference transmitter, and an uplink interference antenna; and the uplink signal of the GSM mobile phone in the shielding area. Captured by the uplink receiving antenna, filtered by the filter, and then transmitted to the power detection comparator, and detects whether the uplink signal strength reaches the set power level threshold during the uplink time slot period, and determines the mobile phone that transmits the uplink signal. Whether it is located in a shielded area; For a mobile phone determined to be located in a shielded area, the power detection comparator sends a signal to the interference transmitter to notify the interstitial interference signal whose emission strength is greater than the uplink signal strength of the mobile phone to shield the mobile phone.

As a technical solution, the filter includes a carrier filter module, which is used to filter the uplink signal of the mobile phone; the signal in the shielded area is captured by the uplink receiving antenna, filtered by the carrier filter module, and transmitted to the power detection. The comparator discriminates whether the signal is a mobile phone signal, and for a mobile phone signal, detects whether the signal strength reaches a set power level threshold, and determines whether the mobile phone transmitting the uplink signal is located in a shielded area. For a mobile phone located in a shielded area, the power detection comparator sends a signal to an interference transmitter to notify it to transmit a slot interference signal to shield the mobile phone.

As another technical solution, the filter further includes a shielding interference signal filtering module, and the shielding interference signal filtering module is configured to filter signals transmitted by other shields in the shielding system; the signals in the shielding area are transmitted through an uplink receiving antenna. After capture, they are filtered by the carrier filter module and the shielded interference signal filter module and then sent to the power detection comparator to identify whether the signal is a mobile phone signal. For those that are judged to be mobile phone signals, check whether the signal strength reaches the set power level threshold. , And use this to determine whether the mobile phone transmitting the uplink signal is located in the shielded area; for the mobile phone determined to be located in the shielded area, the power detection comparator sends a signal to the interference transmitter to notify it to transmit the slot interference signal to shield the mobile phone.

In the above two technical solutions, the power detection comparator can be identified by the difference between the signal characteristics of the mobile phone signal and the signal characteristics of other shields in the shielded area, such as the different characteristics of the frequency spectrum, center frequency, etc .; The difference in the output power of the filter is used to detect and discriminate. Because the power of the shielded transmission signal is within the corresponding shielded filter band set according to the characteristics of the shielded signal, when other shields transmit shielded interference signals, but no mobile phone transmits signals. In comparison, the detected power of the carrier filter is basically the same as the detected power after the shielding filter, so if the power obtained by the shielding filter is basically the same, it is considered to be the signal emitted by the shield; otherwise, if the mobile phone The power of the transmitted GSM signal is distributed within the GSM carrier bandwidth. The shielding filter only has a part of the power because the GSM carrier filter has only a part of the bandwidth. That is, the power obtained by the GSM filter is much larger. Signal, according to the above differences, so as to identify the shield Transmitting signals between each other to prevent lifting shield and multiple self-excited.

As a technical solution, the carrier filter module and the shielded interference signal filter module have different working center frequencies and different bandwidths. Preferably, the bandwidth of the carrier filter module is 200 kHz, and the bandwidth of the shielded interference signal filter module is 20 kHz.

Preferably, the center frequency of the interference signal transmitted by the uplink interference transmitter is offset by a certain amount from the center frequency of the carrier signal. The decision frequency of the corresponding receiving circuit corresponding to the modulation change corresponding to the symbol transition is as close as possible to increase the disturbance to the anti-interference circuit of the mobile phone decoding to increase the shielding power efficiency. For example, the center frequency of the interference signal transmitted by the uplink interference transmitter is the center frequency offset of the carrier signal + 60kHz, or + 67kHz, or + 74kHz, or -60kHz, or -67kHz, or -74kHz.

In summary, the present invention utilizes the characteristic that the uplink signal transmitted by a GSM mobile phone has at least one uplink time slot period. After identifying and determining that the mobile phone is located in a shielded area, it transmits an interference signal with the same time slot as the uplink signal to achieve GSM The shielding of mobile phone communication, the interference implemented in this uplink time slot will not affect the normal communication of other users, and achieves no unnecessary emissions, effectively reducing energy waste and pollution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of differences in uplink transmission time slots corresponding to GSM mobile phones of different base stations;

FIG. 2 is a schematic diagram of a time slot shielding principle of the present invention in Embodiment 1. FIG.

FIG. 3 is a schematic diagram of time slot allocation in Embodiment 1; FIG.

4 is a schematic structural diagram of a shielding system according to the present invention in Embodiment 2;

5 is a schematic structural diagram of another shielding system according to the present invention in Embodiment 3;

6 is a logic diagram of the working principle of the power detection comparator in Embodiment 3;

FIG. 7 is a schematic diagram of the position of the working bandwidth and the center frequency of the carrier filter module and the shield interference signal filter module when the shielded transmission slot interference signal is a positive frequency in Embodiment 3.

detailed description

Example 1

The present invention will be described in detail below with reference to the drawings and embodiments. As shown in FIG. 2, the present invention discloses a method for shielding a GSM mobile phone signal. The method includes the following steps:

(3) For a mobile phone determined to be located in a shielded area, a shielded interference signal of a slot is emitted, so that the strength of the interference signal is greater than the strength of the uplink signal transmitted by the mobile phone to interfere with the reception of the base station, thereby interrupting the mobile phone communication.

Most of the existing technologies use the interference of the downlink frequency of the GSM mobile phone to achieve shielding, and the present invention subverts the interference of the uplink frequency of the GSM mobile phone to achieve the purpose of shielding. Since the interference is directed to a single mobile phone, only when it detects that there is a GSM mobile phone transmitting in the shielding area, the shielding interference of the simultaneous slot is transmitted. By using the feature that the uplink signal transmitted by the mobile phone has at least one uplink time slot period, since the power of the GSM uplink time slot is basically constant throughout the length of the time slot, it is only necessary to detect the power of the previous part of the time slot. Think of it as the power level of the time slot, and identify whether the mobile phone is located in the shielded area based on this. For the mobile phone that is located in the shielded area after discrimination, the slot interference is transmitted during the remaining time of the slot length to interfere with the base station reception. So as to achieve the purpose of shielding mobile phones. Since the GSM base station allocates independent uplink time slots for each mobile phone user, as far as the GSM base station is concerned, the interference implemented by the present invention during the uplink time slot period will not affect the normal communication of other mobile phone users. The invention realizes no unnecessary emission and effectively reduces energy waste and pollution.

Before transmitting the shielding interference signal of the time slot, the uplink time slot training method is used to obtain the uplink time slot boundary and the time slot length of the uplink carrier of the mobile phone. The time slot boundary includes a time slot start boundary and a time slot end boundary. The time slot boundary and the time slot length constitute the uplink time slot period. Specially, when there is only one mobile phone that needs to be shielded in the shielded area, the shield is not turned on, and only the uplink signal is received. After receiving one or more timeslot signals completely, the uplink timeslot boundary of the carrier is obtained. Train the base station 1, and then perform interference after starting the time slot level comparison after the mobile phone transmits the uplink signal again through the alignment recognition. For the case that there may be multiple mobile phones in the shielded area, because these mobile phones may access different base stations respectively, the boundaries of the uplink time slots of these mobile phones may not be perfectly aligned, that is, there is a certain offset; In the case where the slot boundaries are not aligned, another uplink slot training needs to be started to obtain the slot boundary of another base station, and the training base station 2 is obtained, and the slot start boundary alignment is correctly identified by synchronization before entering the next shielded transmission. , And so on, in this way, it can filter the interference of the shielded emissions transmitted by the radio frequency interference that is not aligned with the starting boundary of the base station to the shielded mobile phone's uplink time slot signal identification system.

It should be noted that in general, when transmitting interference is shielded, unless the transmitting antenna is far away from the shield, the uplink receiving circuit of the mobile phone in the same frequency band has a large blocking interference; therefore, when shielding the transmitting interference, it is also considered to turn off the reception of the mobile phone's uplink signal. This results in a time discontinuity in the receiving circuit and adversely affects the reception processing, such as affecting the reading of the uplink time slot boundary during shielded transmission interference; the uplink signal transmitted between all mobile phones under a base station is The time slots are aligned, that is, after the shielded transmission is turned off, it is just the beginning of the next time slot; therefore, the present invention can shield all the mobile phones in the shielded range of the same base station without omission. The base station 1 is trained based on time slots. The present invention uses the time slots to train the base station time slot cycle. First, all mobile phones under this base station are shielded, that is, after blocking for a period of time, all mobile phones are disconnected from the network, and then received for a period of time to verify Whether the mobile phones in the shielded area are offline, that is, the mobile phone that is not aligned with the base station time slot training cycle transmits an uplink signal; then find the mobile phone corresponding to the base station time slot training cycle. Repeating this can block all All phones in the masker area under different base stations. As shown in Figure 3, the uplink time slot period transmitted by the mobile phone includes a detection discrimination period and a shielded transmission period. The identification detection period is used to detect whether the uplink signal strength reaches a set power level threshold; the uplink signal strength exceeds the set power For the level threshold, the shielding interference signal of the time slot is transmitted during the shielding transmission period, and the strength of the interference signal is greater than the strength of the uplink signal transmitted by the mobile phone to interfere with the reception of the base station, thereby interrupting the communication of the mobile phone.

Example 2

As shown in FIG. 4, this embodiment discloses a GSM mobile phone signal shielding system, which mainly includes an uplink receiving antenna, a filter, a power detection comparator, an interference transmitter, and an uplink interference antenna; the filter here is a carrier filter module. . The uplink signal of the GSM mobile phone in the shielded area is captured by the uplink receiving antenna, filtered by the filter, and transmitted to the power detection comparator to detect and identify whether the uplink signal strength reaches the set power level threshold during the uplink time slot period. And use this to determine whether the mobile phone transmitting the uplink signal is located in the shielded area; for the mobile phone determined to be located in the shielded area, the power detection comparator sends a signal to the interference transmitter to notify the transmitter that its transmission strength is greater than the uplink signal strength of the mobile phone. Interfering with the signal to shield the phone.

Example 3

As shown in FIG. 5, the ellipse inside is a large shielding area. In this area, in addition to the shielding system (virtual frame part), there are shield 1, shield 2, shield 3, and Shielding device 4. Different from Embodiment 2, the filter in the shielding system includes a carrier filtering module and a shielding interference signal filtering module. The carrier filtering module is used to filter the uplink signal of the mobile phone, and the shielding interference signal filtering module is used to filter other signals in the shielding area. Interference signals emitted by the masker are filtered. The carrier filter module and the shielding interference signal filter module have different working center frequencies and different bandwidths.

In the case of a large shielding range, it is usually necessary to arrange multiple shields in the shielded area so that the entire area has a good shielding effect. In order to avoid the mutual lift of multiple shields, the shield interference from other shields is mistakenly interfered. The signal is regarded as the uplink signal transmitted by the mobile phone. Before transmitting the interference signal of the same frequency, it is necessary to discriminate the uplink signal transmitted by the mobile phone and the shielding interference signal sent by other shields. The signal in the shielded area is captured by the uplink receiving antenna, filtered by the carrier filter module and the shielded interference signal module in the filter, and then transmitted to the power detection comparator. The power detection comparator first identifies whether the signal is a mobile phone during the detection period. For signals that are judged to be mobile phone signals, it is then detected whether the power level of the uplink time slot reaches a set threshold, and to determine whether the mobile phone transmitting the uplink signal is located in a shielded area; For a mobile phone, the power detection comparator sends a signal to an interference transmitter to notify it to transmit a slot interference signal to shield the mobile phone, as shown in FIG. 6.

For multiple shields transmitting the same frequency interference signal to work together to expand the shielding area, there may be the following problems: multiple shields have detected the interference of the same mobile phone at the same time and transmitted shielding interference signals. These same frequency signals may arrive due to There is a time difference at the receiving antenna, which becomes similar in power and opposite in phase, and is superimposed on each other to cancel it out. As a result, the shielded transmission signal received by the base station is not strong enough to cause shielding failure. Therefore, when setting, the frequency of the signal transmitted by the shield should be different from that of the nearby equipment, that is, the interference signals that are transmitted are grouped. The adjacent signals are physically adjacent, and their respective interference signals have different transmission frequencies. Here, the physical neighbor refers to The installation position is adjacent. By setting it in this way, the receiver ’s anti-phase superposition at the receiver, which transmits the same frequency interference signal when the same mobile phone is detected at the same time, will cause the cancellation problem; the same can also prevent the shield Shielded emission detection and reception are cancelled out due to the inverse superposition caused by the same frequency.

As shown in FIG. 7, as a preference, the working bandwidth of the carrier filtering module is 200 kHz, and the working bandwidth of the shielding interference signal filtering module is 20 kHz. Preferably, the interference signal transmitted by the uplink interference transmitter is offset by a certain amount from the center frequency of the carrier signal. The frequency of the interference signal transmitted by the interference transmitter is the carrier center frequency offset + 60kHz, or + 67kHz, or + 74kHz, or -60kHz, or -67kHz, or -74kH.

The uplink reception here uses diversity reception technology, adding diversity reception antennas and diversity reception circuits. Using diversity technology can effectively reduce the poor reception caused by the fast fading effect of GSM uplink signals, and increase the stability of reception.

It can be understood that for those skilled in the art, equivalent replacements or changes to the technical solutions and inventive concepts of the present invention shall all fall within the protection scope of the claims attached to the present invention.

Claims

A method for shielding a GSM mobile phone signal, which is characterized in that the method includes the following steps:

(1) Monitor all uplink frequencies in the shielded area and capture the uplink signals of the GSM mobile phone;

(2) Utilize the characteristic that the uplink signal transmitted by the mobile phone has at least one uplink time slot period, and detect and identify whether the uplink signal strength reaches the set power level threshold during the uplink time slot period, and determine whether the transmitting mobile phone is based on this Located in a shielded area;

(3) For a mobile phone determined to be located in a shielded area, a shielded interference signal of a simultaneous slot is transmitted, so that the strength of the interference signal is greater than the strength of the uplink signal transmitted by the mobile phone to interfere with the reception of the base station, thereby interrupting the mobile phone communication.
The method for shielding a GSM mobile phone signal according to claim 1, characterized in that before transmitting the shielding interference signal of the time slot, it is necessary to perform discrimination between the uplink signal transmitted by the mobile phone and other shielding interference signals in the shielding area; For mobile phone signals, it is further detected whether the uplink signal strength reaches a set power level threshold; for those that are determined to be other shielding interference signals, the next step is suspended.
The method for shielding a GSM mobile phone signal according to claim 1, wherein the uplink time slot period transmitted by the mobile phone includes an identification detection period and a shielding transmission period; and the identification detection period is used to detect and identify whether the uplink signal strength is When the set level threshold is reached, if the uplink signal strength exceeds the set power level threshold, the shield interference signal of the time slot is transmitted during the shield transmission period, and the strength of the interference signal is greater than the strength of the uplink signal transmitted by the mobile phone. Interfering with the reception of the base station, thus interrupting the communication of the mobile phone.
The method for shielding a GSM mobile phone signal according to claim 3, wherein when there are other shielding interference signals in the shielding area, the identification and detection period is further used to distinguish an uplink signal transmitted by the mobile phone from other shielding in the shielding area. Interference signals. For uplink signals determined to be transmitted by mobile phones, it is further detected whether the uplink signal strength reaches the set power level threshold. For uplink signal strength that exceeds the set level threshold, the shield interference of the simultaneous slot is transmitted during the shield transmission period. Signal, and the strength of the interference signal is greater than the strength of the uplink signal transmitted by the mobile phone to interfere with the reception of the base station, thereby interrupting the communication of the mobile phone.
The method for shielding a GSM mobile phone signal according to claim 2, characterized in that, in the shielding area, the transmission frequencies of the shielding interference signals adjacent to each other are different.
The method for shielding a GSM mobile phone signal according to claim 1, wherein an uplink time slot training method is adopted: before transmitting a shielding interference signal of a time slot, obtaining an uplink time slot boundary and a time slot length of a mobile phone uplink carrier, The time slot boundary includes a time slot start boundary and a time slot end boundary, and an uplink time slot boundary and a time slot length constitute an uplink time slot period.
The method for shielding a GSM mobile phone signal according to claim 6, characterized in that in the uplink time slot training method, the base station time slot cycle period is trained by using the time slot, and all mobile phones under one base station are completely shielded, and then the search is performed. The time slot training cycle of the mobile phone corresponding to the other base station, so that all the mobile phones in the shielding area under all the different base stations are sequentially shielded in this order.
The method for shielding a GSM mobile phone signal according to claim 1, characterized in that the center frequency of the interference signal of the transmitted time slot is offset by a certain amount from the center frequency of the GSM mobile phone carrier signal.
The method for shielding a GSM mobile phone signal according to any one of claims 1 to 8, wherein the uplink signal of the GSM mobile phone is obtained by a diversity receiving method.
A shielding system for a GSM mobile phone signal, which is characterized in that it mainly includes an uplink receiving antenna, a filter, a power detection comparator, an interference transmitter, and an uplink interference antenna; the uplink signal of the GSM mobile phone in the shielding area is captured by the uplink receiving antenna After being filtered by the filter, it is transmitted to the power detection comparator to detect and identify whether the uplink signal strength reaches the set power level threshold during the uplink time slot period, and determine whether the mobile phone transmitting the uplink signal is located in the shielded area; For a mobile phone determined to be located in a shielded area, the power detection comparator sends a signal to the interference transmitter to notify the side-slot interfering signal whose transmission strength is greater than the uplink signal strength transmitted by the mobile phone to shield the mobile phone.
The shielding system for a GSM mobile phone signal according to claim 10, wherein the filter comprises a carrier filter module, and the carrier filter module is configured to filter the uplink signal of the mobile phone; the signal in the shielding area is transmitted via an uplink receiving antenna; After capture, it is filtered by the carrier filter module and sent to the power detection comparator to identify whether the signal is a mobile phone signal. For those that are judged to be a mobile phone signal, detect whether the signal strength reaches a set power level threshold, and use this to determine whether to transmit the signal. Whether the mobile phone with the uplink signal is located in the shielded area; For the mobile phone determined to be located in the shielded area, the power detection comparator sends a signal to the interference transmitter to notify it to transmit the slot interference signal to shield the mobile phone.
The shielding system for a GSM mobile phone signal according to claim 11, wherein the filter further comprises a shielding interference signal filtering module, and the shielding interference signal filtering module is configured to implement signals transmitted by other shields in the shielding system. Filtering; the signals in the shielded area are captured by the uplink receiving antenna, filtered by the carrier filter module and the shielded interference signal filter module, and then transmitted to the power detection comparator to identify whether the signal is a mobile phone signal. Whether the signal strength reaches the set power level threshold and determine whether the mobile phone transmitting the uplink signal is located in the shielded area; for the mobile phone determined to be located in the shielded area, the power detection comparator sends a signal to the interference transmitter to notify it The mobile phone is shielded by transmitting a slot interference signal.
The shielding system for a GSM mobile phone signal according to claim 12, wherein the carrier center module and the shielding interference signal filtering module have different working center frequencies and bandwidths.
The shielding system for a GSM mobile phone signal according to claim 13, wherein the center frequency of the interference signal transmitted by the uplink interference transmitter is offset by a certain amount from the center frequency of the GSM mobile phone carrier signal.