Method for concealing electromagnetic channels leaking speech signals in sound-amplifying equipment

FIELD: technology for generating artificial interference for concealing electromagnetic channels leaking speech information.

SUBSTANCE: in accordance to invention, method includes generation, amplification and emission of concealing noise signal, and also substantial changes and additions, namely: noise signal is amplified in mode B or AB, pulse automatic-compensating stabilization of power amplifier powering voltage is utilized, stabilized voltage is filtered by upper frequencies filter, lower limiting frequency is higher than upper frequency of audible spectrum, but lower than frequency of pulse stabilizer.

EFFECT: increased efficiency of method while power for concealed equipment is delivered by industrial alternating-current network.

2 dwg

 

The technical field.

The invention relates to the field of artificial noise for masking electromagnetic leakage channels of voice information.

The level of technology.

It is known that the value of economic, political, scientific and technical information exceed the value of material objects. It is therefore extremely urgent protection from unauthorized leaks of information from the state, defense, scientific-technical and business content.

In addition to organizational measures, prescribing the staff rules, to protect the content information apply sophisticated technical means. In particular, to reduce the leakage of information on acoustic and radio channels, a telephone network, a circuit used equipment, etc. applied special schemes masking information signals, reducing the possibility of unauthorized listening. For example, "a Device to counter unauthorized work wired portable devices and informative disturbances in the mains LGS-220" (passport TU-6379-005-31056649-2002, laboratory PCA certificate gasteromycete of the Russian Federation No. 742 dated 07 April 2003); Rotkiewicz Century, Ratkevich P. "Technique measurements at the radio", M: Communications, 1969, str-381.

In operation Horev AA "Methods and tools for searching the electronic devices intercept information", M: the defense Ministry, p.24 presents examples of network bookmarks that are installed in electrical outlets, extension cords, equipment powered by AC or directly in the power line. Bookmarks are used for retrieval of verbal information. Equipment gain of verbal information should be protected by the channel leak power. Without protective measures amplifying equipment makes a reaction in the network in accordance with the amplified signal, which allows their separation from the network, i.e. the possibility of information leakage. Use power strips and equivalents network in this frequency range is almost not impair the electrical signals. Network filters on the audio frequencies are very bulky and provide a relatively low attenuation (of the order of 5-10 dB) in the range of 100-10000 Hz, which is clearly not enough.

Other information security technical means is the creation of artificial interference in the electromagnetic channels of information leakage generators masking signal power exceeds the rated power of the electromagnetic signals of information leakage. This significantly reduces the possibility of detecting and receiving information.

The present invention is an improvement in this direction. Conventional structural diagram of the masking device is shown, for example, in the book of Ratkevich Century, Ratkevich P. "Technique measurements at the radio", M: Communications, 1969 (str-461, RIS). It contains the generator of the noise signal, the output signal which after amplification is supplied to the load, which is usually the radiating antenna. And both the generator and the amplifier noise signal fed from industrial AC current through the rectifier with a smoothing filter is a lowpass filter. It is usually performed on an L-C elements (figure 1).

The described method is most similar to the claimed most essential features, so it is selected as a prototype.

Method of masking electromagnetic leakage speech signal amplification equipment - prototype provides the following operations. Generate the masking signal and, if necessary, amplify it, and radiate in the air, for example, raising them to the antenna. And both the generator and the amplifier noise signal is fed through a rectifier from industrial AC.

The method is as follows. After connecting the rectifier to the industrial network AC voltage is rectified by the rectifier is then filtered by the filter power filter lowpass charges the filter capacitor of the power supply and is supplied to the generator of the noise signal, which starts to generate noise is ignal. This signal, amplified by the amplifier is also connected to the filter capacitor of the power of the rectifier energizes the load (antenna), which emits in the ether powerful electromagnetic noise signal, the mask spurious, unwanted electromagnetic radiation masked the sound amplification equipment, noise which is the claimed method. The power output of the noise signal must substantially exceed the power of the electromagnetic signal leakage of the masked speech signals.

The method can be effective in cases of power masked equipment from independent power sources. They prevent or significantly reduce electromagnetic information leakage through the airwaves.

However, when the power of the masked equipment from industrial AC leaks not only air, but also through the specified industrial AC.

The mechanisms of formation of these leak paths can be followed.

The change in current consumption, especially high power amplifiers, in accordance with the voice information causes a corresponding change in the AC. Because of this, of course, specified speech information can be extracted from the AC (outside protected areas) for unauthorized eavesdropping.

The AOC is e, high-frequency noise on the power supply circuit can easily penetrate in the amplifier stages, where they are modulated speech signal, and then penetrate back into the mains supply and/or radiate out into the ether.

The prototype method is it does not mask the channels of information leakage through the industrial network power, formed by the above way, since the emitted broadcast electromagnetic masking noise signal mask only essential electromagnetic leakage channels.

The most obvious two ways to circumvent this:

a) feed protected from equipment leaks (masked equipment) only from Autonomous sources of power, i.e. without the use of a shared industrial network, but this is not always possible and expensive;

b) to enter into the food chain each masked equipment surge suppressing the speech signal that requires significant additional costs (see, for example, p.8, 11 C, d and e in the book Kostikova VG, Parfenova EM and Sakhnova VA "Sources of power electronic means. The system engineering and design". Textbook for high schools, 2nd ed., Moscow Hot line - Telecom, 2001). Network filters to suppress speech range require very large inductances. Practically they weaken the voice frequency is not more than 10 dB, which is obviously insufficient for IP is your information leakage. In particular, the network filter prototype for these purposes, useless.

The objective of the invention.

The task of the invention is to increase the efficiency of the method when the power is masked equipment from industrial AC.

The solution of the problem.

The problem is solved by the fact that in the known method of masking electromagnetic leakage channels of speech signals, sound equipment, including the generation, amplification and radiation masking electromagnetic noise signal power generator and amplifier noise signal from industrial AC made significant changes and additions, namely:

- amplification of the noise signal produced in mode b or AB,

- apply a pulse autocompensation stabilization voltage generator and amplifier noise signal,

- filter the stabilized voltage of the high-pass filter, the lower cutoff frequency above the upper frequency of the audible spectrum, but lower clock frequency switching regulator.

In addition, to improve the efficiency of the electromagnetic masking pulse autocompensation stabilizer is better not to escape.

In other words, inventive problem - introduction to industrial AC powerful noise current component - resolved two are inextricably related technical solutions: the creation of a powerful electric current, shape close to the generated noise signal, and finding a simple way of introducing it into industrial AC.

The first solution consists in the application of the regime In power amp noise signal. In this mode, the instantaneous amplitude passing through the current amplifier is almost directly proportional to the instantaneous amplitude of the amplified them a signal. Thus, in our case (the gain of the noise signal) of the power supply circuit of the amplifier will be current, identical to the amplified noise signal. Of course, in AV mode, this dependence is passing current from the amplified signal is mitigated somewhat. Note that in mode And it is absent at all.

The second solution is to connect the amplifier to an industrial AC current through pulse autocompensation the voltage regulator (see, for example, V.G. Kostikov, E.M. Parfenov, VA Shachnow "power electronic means. Schematic and design", textbook for universities): Hot line - TELECOM, 2001, p.10-19).

As is known, the voltage regulator consumes from the industrial network current, instantaneous value of which is proportional to the instantaneous values of current to its load. In our case, when the power of the noise signal through pulse autocompensation voltage stabilizer posledniye to consume commercial power supply current, corresponding in shape to the current of the amplified noise signal.

To avoid this circuit the current through the output filter regulator filter output voltage produced by the high-pass filter, the lower cutoff frequency above the upper frequency of the audible spectrum, but lower clock frequency switching regulator.

Thus, the proposed changes to the way the masking of speech signals has allowed a very simple means to enter into industrial AC powerful noise signal, a frequency which is close to the composition of the generated noise signal. The latter, as is well known, masks electromagnetic signals of all of the audible spectrum.

Disclosure of the invention.

The invention is illustrated by the two figures, which show examples of block diagrams of the method for masking speech signal (figure 1) and pulse autocompensating voltage of the power amplifier of the noise signal (figure 2).

In the figures, the following notation:

1 - industrial AC current 2 - voltage rectifier network 3 - smoothing filter (lowpass filter), 4 - noise signal generator, 5 - amp noise signal, 6 - emitter noise signal (e.g., antenna), 7 - sound amplifying equipment, 8 - pulse is lsny autocompensation biasing voltage, 9 - key cascade, 10 - pulse transformer, 11 - output rectifier, 12 a high - pass filter, 13 - source reference voltage, 14 - comparator 15 - pulse-width modulator 16 - power PWM signal, 17 - oscillator sawtooth signal.

The method is as follows. After connecting the rectifier to the industrial network 1 voltage is rectified by the rectifier 2, and then stabilized pulse autocompensation stabilizer 8 is filtered by high-pass filter 12 and is supplied to the generator 4, which begins to generate a noise signal. This signal, amplified by the amplifier 5, is also connected to the output autocompensating stabilizer 8, stimulates the load (antenna) 6, which emits in the ether powerful electromagnetic noise signal, marking stray, unwanted electromagnetic radiation masked sound equipment, powered industrial network 1 alternating current through the rectifier 2 and the low pass filter 3. The power radiated electromagnetic noise signal must substantially exceed the capacity of the electromagnetic signal leakage of the masked information signals (speech signals).

As for the masking of speech signals in a circuit, it is due to the special mode of the amplifier 5 power and the noise signal, and the introduction of pulse autocompensating stabilizer 8 voltage between the rectifier 2 and the power amplifier 5. Next, it is explained in more detail.

Pulse autocompensation stabilizer 8 voltage works as follows. Voltage industrial network 1 alternating current is rectified by the rectifier 2, is fed to the input key cascade 9, passes through it in accordance with the PWM control signal received at a control input of the cascade 9, forms a voltage to a winding of the pulse transformer 10, which is fed to the rectifier regulator (output rectifier) 11, after which the terminals of the power amplifier 5 and the generator 4. The PWM control signal key cascade 9 is formed by comparing the output voltage of the pulse transformer 10 (respectively, the output voltage of the stabilizer 8) with the reference voltage source 13. The comparison produces a comparator 14, the input of which receives the comparison voltage. In case of equality of voltages output signal of the comparator 14 is connected to the PWM modulator 15, is equal to zero. Because the PWM modulator 15 is configured so that its output PWM signal is greater, the greater the signal at the output of the comparator 14, in the case of a zero signal at the output of the comparator 14 PWM signal at its output is missing. Only through the stabilizer 8 will be the current of the power amplifier 5 of the noise signal, the voltage at the output of pulse transformer 10 and the stabilizer is ora 8 will decrease, will have the proper voltage at the output of the comparator 14, is formed proportional to the PWM signal, the opening key cascade 9.

Because you selected the mode (or AB) operation of the power amplifier 5 of the noise signal, the instantaneous value of its current proportional to the amplified noise signal. I.e. opening and locking key cascade 9, is connected directly to the rectifier 2 industrial AC will also repeat the instantaneous value of the noise signal. Note that the filter 12 output rectifier is a high - pass filter, the lower cutoff frequency above the upper frequency of the audible spectrum - to save the current shape of the noise signal in industrial AC. However, this frequency must be lower than the clock frequency of the pulse voltage stabilizer for smoothing the shape of the rectified voltage.

Since the mode of the amplifier 5 to the power of the noise signal of the selected class B (or AB), the instantaneous amplitude of its commercial power supply 1 current amplitude proportional to the instantaneous amplitudes of the amplified them a signal, i.e. the power of the noise signal. In other words, in the industrial network 1 AC current flows, the spectral form which repeats the spectral shape of the generated noise signal.

Naturally, the flow of current such forms in industrial network 1 AC has the same masking effect on the signals of possible leakage of information, what produce electromagnetic signals radiated by the antenna to possible signals of information leakage through the airwaves.

Thus, the application of class b or AB amplifier power noise generator and power from industrial AC current through pulse autocompensation voltage regulator with a high-pass filter on the output is allowed to enter the powerful masking noise signal in industrial AC is extremely simple and cheap way.

Industrial applicability.

The claimed method is easy to implement known and long-established industry scheme and constructive means. Rectifiers, filters, generators and amplifiers are traditionally. Pulse autocompensation the stabilizer may be performed, for example, in accordance with the recommendations of the guidelines "power radio", Saint-Petersburg state Academy of aerospace instrumentation, Saint-Petersburg, 1995, p.27-32.

The applicant has fabricated and tested a device reproducing the claimed method. The test results showed that the protection of equipment from bore is mclonergan leakage of sound information along the food chain is increased by 2-3 times, depending on the power of amplified sound equipment of the speech signal.

The cost of changes and extra money was incomparably lower in comparison with the known solutions to this problem, and the efficiency is much higher.

Thus, in our opinion, the claimed method meets all the criteria of the invention - it is new, not obvious and industrially applicable.

Method of masking electromagnetic leakage channels of speech signals, sound equipment, powered industrial AC, including the generation, amplification and radiation of the masking noise signal, wherein the gain of the noise signal produced in mode b or AB, apply a pulse autocompensation the voltage of the power amplifier, while filtered stabilized voltage by the high-pass filter, the lower cutoff frequency above the upper frequency of the audible spectrum, but lower clock frequency switching regulator.



 

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