RU2363106C1 - Method of local suppression of mobile communication - Google Patents

Abstract

FIELD: communication devices.

SUBSTANCE: invention relates to radio engineering and more specifically to methods of upsetting normal operation (suppressing) radio-electronic devices, particularly mobile telephones, by generating artificial noise and suppressing data flow in GSM standard wireless networks. The technical outcome is achieved by simplifying settings and preventing system self-excitation. For this purpose, in a working or communication establishing mobile telephone in which there is reception of a signal, there is measurement of carrier frequency and time slot of the received signal. A narrow-band suppression signal is generated and beamed on the corresponding duplex frequency receiving channel of a mobile telephone at time instants set for the given telephone for receiving from a base station in accordance with a previously measured time slot. The method enables blocking the mobile telephone of a subscriber located inside the blocking zone only, and only during transmission of a signal from a base station to that subscriber, which prevents communication establishment by the subscriber in the given zone. The mobile telephone receives all general information and therefore remains in service in the network. Impossibility of establishing communication guarantees call failure, that is, no calls and silence.

EFFECT: higher quality of local suppression of mobile communication.

1 dwg

Description

The invention relates to the field of radio engineering, and in particular to methods of disrupting the normal operation (suppression) of electronic devices, in particular mobile phones, by creating artificial interference and suppressing information flows in GSM radio networks.

It is known that the use of a mobile phone is undesirable inside some rooms, in particular in meeting rooms and meeting rooms, in rooms and buildings of law enforcement agencies. The use of a mobile phone is prohibited inside many state institutions and sensitive enterprises working with state secrets. Silence is also necessary in museums, concert halls, churches and classrooms. Therefore, in the field of information security, a new task has appeared - detecting the operation of a mobile phone in a protected area and blocking its work in order to prevent unauthorized transmission of information.

A known method of local suppression of mobile communication, including amplification of the received broadband signal of a mobile phone and its re-emission with phase manipulation according to the law of a low-frequency pseudo-random sequence, in which phase manipulation is performed with the received and amplified signal in real time, and the spectrum of the re-emitted signal is kept within frequency bands of a mobile phone. At the same time, the broadband signal of the mobile phone is received by a narrowly directed antenna from the protected local area, and the signal is re-emitted in any part of the base station zone receiving the signal from the specified mobile phone (RF Application No. 2003127794, published 03.10.2005).

A disadvantage of the known technical solution is the reception of a broadband signal from mobile phones, its modulation (distortion), amplification and re-emission at the same frequencies, that is, from a mobile phone (MT) to a base station (BS). This method of local suppression of mobile communications is difficult to configure, and systems operating in this way are prone to self-excitation. In addition, the influence of the suppression signal is produced on the receiver of the base station (BS) in the entire frequency band, which leads to disruption of cellular communications not only in the local zone, but also in the surrounding areas. Therefore, the known method, using only a narrow antenna, cannot suppress cellular communications while taking into account the characteristics of radio wave propagation in urban conditions

The technical result that this invention is directed to is to improve the quality of the method for local suppression of mobile communications by simplifying the configuration and eliminating self-excitation of the system.

The specified technical result is achieved due to the fact that in the method of local suppression of cellular communication, including receiving a signal from a working or communicating mobile phone, the carrier frequency and the time slot of the received signal are measured, a narrow-band suppression signal is generated and emitted on the corresponding duplex receiving frequency channel mobile phone at times allocated to this phone for reception from the base station in accordance with the previously measured time slot, while The carrier frequency is produced for 250-300 μs with the time slot fixed, the narrow-band suppression signal at the carrier frequency of the corresponding duplex channel is formed of 102 radio pulses with a duration of 280-300 μs each and a repetition period of 4.615 μs, the spectral width of the narrow-band suppression signal being 20 dB level is 6 kHz.

To explain the implementation of the proposed method, a block diagram of a device that implements a method for local suppression of cellular communications is shown.

The block diagram of a device for implementing the proposed method contains the following notation:

1 - antenna switch,

2 - power amplifier,

3 - pre-amplifier,

4 - transmitter frequency synthesizer,

5 - high-frequency splitter,

6 - the local oscillator of the receiver of the 1800 MHz range,

7 - 1800 MHz receiver,

8 - low-pass filter for the 1800 MHz range,

9 - amplifier limiter

10 - comparator,

11 - frequency divider by 2,

12 - the local oscillator of the receiver of the 900 MHz range,

13 - 900 MHz receiver,

14 - low-pass filter for the range of 900 MHz,

15 - amplifier limiter

16 - comparator

17 is a digital signal processor,

18 - dual-band transmit-receive antenna.

The method of local suppression of mobile communications is as follows.

The 18 900/1800 MHz dual-band receiving and transmitting antenna receives the emitted signal of the mobile phone. The signal received by the antenna 18 through the antenna switch 1 and the high-frequency splitter 5 is fed to the receivers 7 and 13 of the 900 and 1800 MHz bands, in which the signal is directly down-converted with subsequent filtering in low-pass filters 8 and 14. The frequencies of the local oscillators 6 are chosen equal to the center frequencies of the corresponding bands, so the passband of the low-pass filters is chosen equal to half the bandwidth - 17.5 MHz for the 900 MHz band and 37.5 MHz for the 1800 MHz band. Next, the filtered signal is amplified by a limiter-amplifier 15 for the 900 MHz range and a limiter-amplifier 9 for the 1800 MHz range, then it is compared with a comparator 10 or 16, and the frequency of the signal emitted by the mobile phone is calculated in the digital signal processor 17.

After completion of the calculation procedure, the digital signal processor 17 installs the frequency synthesizer of the transmitter 4 on the corresponding frequency channel of the transmitter of the base station (not shown) and turns on the power amplifier of the suppression signal at those times when the base station transmits information intended for this particular subscriber.

An example implementation of the method of suppressing mobile communications.

By the first pulse transmitted from the mobile phone to the base station, a mobile phone is detected. Then, within 300 μs (possibly in the range of 250-300 μs), the carrier frequency (frequency channel) is measured and the temporary position of this pulse (time slot) is recorded. With a time delay of 2885 Moscow time relative to the pulse transmitted by the mobile phone, an interference of 102 radio pulses with a pulse duration of 300 μs (possibly in the range of 280-300 μs), a repetition period of 4.615 μs, and a width of 4,615 μs are set on the carrier frequency of the corresponding duplex channel of the base station the interference spectrum at a level of 20 dB will be 6 kHz.

As a result, the mobile phone is deprived of the opportunity to receive from the base station the information necessary to establish communication.

When making another attempt to establish communication in the mode of the telephone entering the communication until the end of the impulse noise, the noise is turned off, and the above steps to detect a mobile phone are repeated. The blocking time for this communication mode is approximately 1 s. As a result of the implementation of this method of blocking, communication is not established, calls do not pass, but the mobile phone is constantly being serviced on the network, as it is able to freely receive general information from the base station.

If the mobile phone is in the already established communication mode, the sequence of actions of the method of suppressing mobile communication remains the same, only the blocking time for this mode is 15-20 s.

Thus, the inventive method allows you to block a mobile phone only to a subscriber located inside the blocking zone, and only at the time the base station transmits the signal to this subscriber, which does not allow him to enter into communication within a given zone. The mobile phone receives general information in full and therefore remains on service on the network. The impossibility of establishing a connection guarantees the failure of the call, that is, the absence of calls and silence.

Claims (1)

A method for locally suppressing cellular communication, including receiving a signal from a working or communicating mobile phone, characterized in that the carrier frequency and the time slot of the received signal are measured, a narrow-band suppression signal is generated and emitted on the corresponding duplex frequency channel for receiving the mobile phone at times assigned to this telephone for reception from the base station in accordance with the previously measured time slot, while the measurement of the carrier frequency is carried out for 25 0-300 μs with fixing the time slot, and the narrow-band suppression signal at the carrier frequency of the corresponding duplex channel is formed from 102 radio pulses with a duration of 280-300 μs each and a repetition period of 4.615 μs, the width of the spectrum of the narrow-band suppression signal at a level of 20 dB is 6 kHz .