RU2183914C1 - Device for protecting cellular radiophone against unauthorized hearing in remote information access mode - Google Patents

Abstract

FIELD: means for protection against commercial and industrial espionage. SUBSTANCE: device has series-connected auxiliary antenna and cellular-radiophone radiation detector, as well as series-connected auxiliary microphone, amplifier, amplitude detector, controlled noise generator, and masking loudspeaker. Auxiliary antenna is mounted for receiving cellular-radiophone radiation as working signal when setting radio transmission mode. Output of radiophone radiation loudspeaker is connected to starting input of noise generator. Auxiliary microphone is installed for responding to voice signals listened to by unauthorized persons; masking loudspeaker is mounted for conveying acoustic noise to cellular-radiophone microphone when dropping it in device casing and switching under effect of gravity force of power supply switch. Invention is characterized firstly in that acoustic noise generation is made impossible in absence of attempts to listen to secret talks and secondly in that noise generator is controlled to ensure that generated acoustic noise level is proportional to voice signal level. Device incorporates provision for purposeful starting and adaptation to level of masked voice signals. EFFECT: enhanced effectiveness of protection, improved comfort for conferee. 4 cl, 1 dwg

Description

 The invention relates to techniques for countering commercial and industrial espionage.

 Known devices for preventing unauthorized listening to conversations in rooms with telephones connected to the subscriber line, based on switching bodies, designed to break or short-circuit the line at rest (DE 1487453 A, 01/16/1969; EP 0365741 A2, 05/02/1990; RU 2145153 C1, 01/27/2000).

 Such devices, when implemented, require substantial modernization of existing telephone systems.

 Devices for the exclusion of listening are also known, based on the use of jammers that impede dialing from an external telephone connected in parallel or interfere with the perception of speech signals on it (FR 2655224 A1, 05/31/1991; RU 92006880 A, 01/20/1995).

 Closest to the proposed one is a protective device, the main functional unit of which is a controlled interference generator that transmits an interference signal to a subscriber telephone line to actually block another person’s subscriber (RU 14794 U1, 08.27.2000).

 A disadvantage of the known device, selected as the closest analogue, is associated with the formation of acoustic noise only in the final section of the telephone communication channel, namely in the subscriber’s handset, which determines the possibility of simple interference filtering. In addition, in the known device, the control of the generator is limited only by its excitation and shutdown, which does not allow to coordinate the protection characteristics with the current environmental conditions.

 The objective of the invention is to increase the effectiveness of protection, as well as ensuring its targeted start-up and adaptation to the level of masked speech signals, i.e., creating comfort for negotiators by eliminating acoustic noise in the absence of attempts to listen to and adjust the level of acoustic noise depending on the volume of speech in indoors.

 The problem is solved in that in the device for protecting a cell phone from unauthorized listening in the mode of remote information access, containing sequentially connected controlled noise generator of a sound range and a masking speaker, as well as a power source connected to the supply circuits of electronic nodes through a switch, sequentially connected an auxiliary antenna and a radio emission detector of a cell phone, as well as an auxiliary microphone connected in series, a separator and an amplitude detector, while all the components of the device are located in a common casing, which has a cavity for installing a cell phone with switching under the influence of its gravity switch of the power source, an auxiliary antenna is installed with the possibility of receiving radiation of a cell phone as a working signal when it is introduced to the radio transmission mode, the outputs of the radio emission detector of the cell phone and the amplitude detector are connected respectively to the start and control inputs of the interference generator, ogatelny microphone is installed to sense the subject of unauthorized interception of voice signals, and masking speaker - to guide the acoustic noise generated in the cellular phone microphone when it is lowered into the cavity of the device housing.

 Partial essential features of the invention contribute to the solution of the problem.

 The interference generator is configured to generate “pink” noise in the frequency range 300 Hz - 4.5 kHz.

 A shunt electronic key is installed at the starting input of the interference generator, excluding the excitation of the generator in the absence of a signal from the radio emission detector of the cell phone.

 The masking speaker is configured to emit acoustic noise with an intensity proportional to the signal level from the auxiliary microphone, but not less than 5 times this level.

 Note that noise simulators controlled by the detection of speech activity (RU 2151430 C1, 06/20/2000) have become widespread in the cellular telephone technology. However, in known technical solutions, such control is used to improve the sound quality in the receiver. To detect speech in a received speech signal when operating in the presence of noise, the speech activity detector uses an energy estimate. In the absence of speech, the signal is attenuated and the low-pass filtering white noise (i.e. comfort noise) of the appropriate level is introduced. This comfort noise mimics the typical spectral characteristics of a car or other background noise. Thanks to this, the "twist" is smoothed out, and the sound is made more natural. When the presence of a speech signal is detected by the speech activity detector, the synthesized speech signal is processed without attenuation. Thus, the increase in comfort at the point of not transmitting, but receiving speech signals, i.e. the technical result is achieved different than in the proposed method.

 The drawing shows a functional diagram of the proposed device.

 The proposed device that protects the cell phone 1 from unauthorized listening in the mode of remote information access and, thereby, prevents listening to confidential conversations in the premises with the cell phone 1, contains sequentially connected auxiliary microphone 2, amplifier 3, amplitude detector 4, controllable noise generator 5 sound range and a masking speaker 6. In addition, the device includes sequentially connected auxiliary antenna 7 and a radio detector 8 cell phone, the output of which is connected to the starting input of the interference generator 5.

 The auxiliary antenna 7 is installed with the possibility of receiving as a working signal the radiation of the cell phone 1 when it is entered into the radio transmission mode.

 All components of the device are placed in a common casing, which has a cavity for installing a cell phone 1 with switching under the influence of its gravity switch 9 of the power source 10 electronic nodes.

 The auxiliary microphone 2 is installed with the ability to perceive speech signals subjected to unauthorized listening, and the masking speaker 6 with the ability to direct the generated acoustic noise into the microphone of the cell phone 1 when it is lowered into the cavity of the device casing.

 The jammer 5 in a particular case is synthesized with the possibility of generating "pink" noise in the frequency range 300 Hz -4.5 kHz.

 A shunt electronic key (not shown) is installed at the start input of the interference generator 5, which excludes the excitation of the generator 5 in the absence of a signal from the radio emission detector 8 of the cellphone 1.

 The masking speaker 6 is configured to emit acoustic noise with an intensity proportional to the signal level from the auxiliary microphone 2, but not less than 5 times this level.

 Position 11 in the drawing marked the cell phone of the attacker, with which an attempt is made to listen to confidential negotiations.

 Protection against listening is implemented by the proposed device as follows.

 Currently, for the implementation of industrial and commercial espionage, unauthorized wiretapping of negotiations conducted in the premises with the help of telephones installed there, is widely used, including with cellular communications. Moreover, listening can be performed even when the subscriber’s handset is not picked up and the cell phone is not turned on, for example, by sending high-frequency vibrations to the telephone’s microphone, where they are modulated by the participants in the negotiations.

 In this case, to prevent unauthorized listening to conversations before they begin, cell phone 1 is inserted into the cavity of the casing of the protective device. In this case, under the weight of the cell phone 1, the switch 9 is activated and its contacts are closed, through which the electronic components of the device receive power from the power source 10.

 If during the confidential negotiations in the premises the intruder uses the cellular telephone 11 to enter the radio transmission mode, the antenna of the cellular telephone 1 begins to emit radio waves that are received by the auxiliary antenna 7 and detected by the detector 8. The signal from the output of the detector 8 affects the starting input of the interference generator 5 , providing the beginning of the functioning of this unit and the entire protective device as a whole.

 With the start of the protective device, interference generator 5 generates a “pink” noise in the frequency range 300 Hz - 4.5 kHz. These electrical disturbances are applied to a masking speaker 6 performing electro-acoustic conversion. The generated acoustic noise from the speaker 6 is transmitted to the microphone of the cell phone 1, which also receives the speech signals of the negotiators. At an average volume of negotiations, the level of acoustic noise at the entrance of the voice path, as already indicated, is at least 5 times higher than the level of the speech signal. Of course, the emission of acoustic noise does not interfere with the normal call of a cell phone 1.

 Important features of the invention are, firstly, the exclusion of the formation of acoustic noise in the absence of attempts to listen to confidential conversations, and secondly, the control of the noise generator in order to ensure proportionality of the level of generated acoustic noise to the level of the speech signal. In other words, in this technical solution, when detecting listening attempts, there is an automatic tracking of the generated acoustic noise by the volume of negotiations.

 The level of interference generated by the generator 5 and, as a consequence, the level of acoustic noise directly at the microphone of the cell phone 1 is controlled by means of an auxiliary microphone 2, which senses ongoing negotiations in the room, and an amplitude detector 4, which selects the envelope of the speech signal used to control the noise generator 5.

 Thus, all attempts to unauthorized listening to conversations through the cell phone 1 used in the remote access mode are unsuccessful. At the same time, the exclusion of acoustic noise in the absence of listening attempts and the regulation of the level of acoustic noise in the presence of such attempts depending on the volume of speech provides comfort for negotiators. If the negotiations are quiet, then the noise level is quite low. When the volume of negotiations increases, the noise level also increases. As a result, the ratio of the speech signal / acoustic noise from the beginning to the end of the negotiations remains unchanged, which is very beneficial for the overall tone of the participants in the negotiations.

Claims (4)

 1. Device for protecting a cell phone from unauthorized listening in the mode of remote information access, containing sequentially connected controlled noise generator of a sound range and a masking speaker, as well as a power source connected to the supply circuits of electronic nodes through a switch, characterized in that it is introduced in series included auxiliary antenna and a radio emission detector of a cell phone, as well as sequentially connected auxiliary microphone, amplifier and an amplitude detector, while all the components of the device are located in a common casing, which has a cavity for installing a cell phone with switching under the influence of its gravity switch of the power source, an auxiliary antenna is installed with the possibility of receiving radiation from a cell phone as a working signal when it is put into operation radio transmissions, the outputs of the radio emission detector of the cell phone and the amplitude detector are connected respectively to the start and control inputs of the interference generator, auxiliary th microphone is installed to sense the subject of unauthorized interception of voice signals, and masking speaker - to guide the acoustic noise generated in the cellular phone microphone when it is lowered into the cavity of the device housing.  2. The device according to p. 1, characterized in that the interference generator is configured to generate "pink" noise in the frequency range 300 Hz - 4.5 kHz.  3. The device according to claim 1 or 2, characterized in that a bypass electronic key is installed at the start input of the interference generator, excluding the excitation of the generator in the absence of a signal from the radio emission detector of the cell phone.  4. The device according to claim 1, characterized in that the masking speaker is configured to emit acoustic noise with an intensity proportional to the signal level from the auxiliary microphone, but not less than 5 times this level.