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Disclosed is a method of protecting the reading device for data medium in form of a card from unauthorised evaluation or copying of magnetically encoded data which are recorded on the reading device for the data medium in form of a card. A magnetic interference field is generated using an interference field coil. The arrangement of at least one interference field coil is such that an authorised magnetic reading head when reading magnetically encoded data on the data medium in form of a card is also under the effect of the interference field of the interference field coil. An output or resultant signal of the authorised magnetic reading head formed by the useful signal of the data medium in form of a card and the effect of the interference field is detected. The effect of the interference field of the interference field coil on the output or resultant signal of the authorised magnetic reading head is compensated for or filtered, or the useful signal is selectively filtered off from the output or resultant signal of the authorised magnetic reading head. |
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Method for information protection in distributed random antenna Distributed random antenna protection device has N interference generators (3) connected to the distributed random antenna through corresponding interface devices (2), and M nonlinear elements (4), where M is less than or equal to N, which are included in the distributed random antenna, wherein each of the M interface devices is connected to the corresponding nonlinear element, through which under the effect of M<N interferences, random integrated-differential frequency conversion of information signals and interference emitted by the distributed random antenna is carried out. |
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Method for information protection of random antenna Method for information protection of a random antenna using a system of jamming emitters involves placing M transponders of the information signal emitted by the random antenna between the random antenna and fixed intercepting equipment. The transponders are connected to amplitude and angular modulators which are connected to M jamming generators which perform stochastic amplitude and angular modulation of the information signals emitted by the random antenna. The fixed intercepting equipment includes N information signal receivers and a computer circuit for processing received signals. |
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Method is carried out by reduction of probability of recognising transmitted data in a communication line. The method to protect information in a communication line against leakage due to external electromagnetic radiation and noise consists in the fact that digital signals transfer along a communication line is terminated. Then this line is complemented with an additional line, and masking signals are sent synchronously together with the transfer along the secured line along this additional line. Besides, amplitude and frequency-time parameters of masking signals are selected so that the picture of external electromagnetic radiations and noise from both lines as a whole that occurs in environment in process of data transfer, is identical for each pulse of transmission. |
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System for transmitting information using random signals Invention relates to information transmission with spectrum broadening and can be used in communication systems. The proposed information transmission system using random signals has an information source, multiplexer, delay line, random signal generator, broadband amplifier, communication channel, high-frequency amplifier, first multiplier, tapped delay line, first integrator, second and third multipliers, first generator of a copy of autocorrelation function of random signal, corresponding to information character "1", second generator of a copy of autocorrelation function of random signal, corresponding to information character "0", second integrator, third integrator, subtractor, decision device and information recipient. |
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Device for protection of user's telephone set against non-authorised acoustic control In device for protection of a user's telephone set against not authorised acoustic control the block (1) connected to a user's telephone line controlling the state of a telephone set with two outputs "handset is free" and "handset is busy", the noise generator, the block of light indication, the block (2) of detection in a telephone line of special signals of guidance, the block (3) of detection of galvanic connection of devices of non-authorised acoustic control, mounted on a telephone line in front of the block (1) controls of a state of a telephone set, and filters (4) system of the inferior frequencies and filters-terminators of the small amplitudes, disposed before a protected telephone set, and also the signals (8) adder, the block (7) of correction of voltage level in a telephone line, the noise generator consists of the block (5) generating "white noise" and the block (6) generating high-frequency noise-like signal, and the indication block (9) in addition contains the block of sound indication. |
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Generator of speech-like noise signal In accordance to the invention, a masking signal should be generated, which simultaneously masks analog signal and speech signal in digital form. Speech-like signal is created on basis of original signal being masked by means of modulation of zero intersection moments of masked signal by a noise signal. To modulate zero intersection moments of speech signal, the speech signal is clipped, and then resulting clipped signal is integrated, transforming it to saw-tooth signal, resulting saw-tooth signal is summed with noise signal, and after that resulting total signal is clipped. To increase masking effect (to exclude pauses, connected to pauses in speech being masked) resulting noise-like signal is summed with second speech-like signal, to generate which noise signal is clipped (which does not have pauses), and then zero intersection points of clipped noise signal are modulated with speech signal. To mask speech signal in digital form, resulting speech masking signal is added to an identical signal converted to digital form. |
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Method for creating a speech-like masking signal Speech-like signal is composed of original signal being masked by modulation with noise signal of moments when signal being masked crosses zero. Modulation of zero crossing moments of speech signal may be performed by phase modulation of speech signal by noise signal. Modulation of zero crossing moments of speech signal may also be performed in accordance to a different algorithm - speech signal is clipped, resulting clipped signal is integrated, resulting saw-shaped signal is added to noise signal, after that resulting digital signal is clipped. For masking speech signal in digital form, resulting masking signal is added to the same signal converted to digital form. Modulating signal is a noise signal. Control listening indicates that resulting signal is unintelligible, although it preserves the speech-like form. |
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Method and device for pulse overlap compensation in digital-modulation signals Proposed method for pulse overlap compensation in digital modulation signal includes reception of first pulse train for producing first train of modulated pulses, demodulation of first modulated pulse train to produce first demodulated pulse train, addition of first demodulated pulse train to first pulse train to produce first error pulse train, modulation of first error pulse train to produce first modulated error pulse train, and addition of first modulated error pulse train to first modulated pulse train to produce compensated pulse train. |
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Method for secret transfer of information In accordance to method, original chaotic determined signal is generated by first chaos generator, transferred via communication channels, received and divided onto two identical signals, while first signal affects second generator with possible production of signal, synchronized to original signal, subtracted from which is second signal, producing useful digital signal, and generation of signal is realized by modulating parameters of chaotic signal by useful one, and second identical signal affects third generator, identical to second one in terms of control parameters, while first and second generators are picked with possible setup of generalized chaotic synchronization mode. |
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Method includes independent emission of each useful signal and broadband masking signal in range of frequencies of whole group of useful signals, their adding and following suppression of masking signal during receipt, while broadband masking signal has value of bearing frequency, divisible by value, reverse relatively to duration of one element of useful digital information and structure, periodical in time, while suppression of masking signal during receipt is performed in accordance to compensation method with delay. |
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Method for protection of speech data signal, transferred along communication lines Transferred signal is concealed via adding noises to communication line in speech frequency range with linear addition of speech data signal with noise signal of higher level. Concealment is removed via adaptive filtration of received signal with compensation of noise component and separation of data component. Addition of noises to communication line is performed from the side of sensor. Noise signal during addition of noises and adaptive filtration is formed of a sum of counts of several noise series with nonevent sizes via their random querying. At the beginning of each communication session a signal is sent to side of receiver, characterizing order of querying of series, and starting signal, providing for synchronism of noises addition and filtering processes. All operations are performed by means of microprocessors, mounted on both sides of communication line, dependently of loaded software providing for change of direction of transmission and protection of speech data signal. Invention allows to simplify protection while providing for absolute confidentiality of transmitted data. |
Another patent 2513124.