RU2374655C2 - Method of determination of accidental antenna parametres - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: method involves action of electromagnetic emission of additional transmitter with frequency f_∂ on accidental antenna emitting signal with frequency f_c, analysis of frequencies of intermodulation products of accidental antenna emission; by means of measuring receiver unknown frequency f_c of signal emitted by accidental antenna is determined; calculation is performed for minimum possible value of additional transmitter frequency: and maximum possible value of additional transmitter frequency: by means of sweep-frequency generator connected to additional transmitter frequency of external action on accidental antenna is changed within limits f_∂.min. : f_∂.max and by means of terminal device connected to measuring receiver levels of power flow density Π₀ and Π_i or of electric field intensity E₀ and E_i are measured correspondingly at frequencies f_c and f_j of signals in measuring receiver location; relative levels of intermodulation products of accidental antenna emission are calculated according to formulae.

EFFECT: increase of accuracy and validity of results of determination of accidental antenna parametres pertaining to all channels of confidential information leakage which is possible in it.

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Description

The invention relates to techniques for radio measurements and can be used to determine the parameters of radio systems, combined by the term "random antennas" (SA).

The presence of antennas (transmitting, receiving, receiving and transmitting) is a characteristic feature of any radio system and any radio channel. At the same time, an antenna is understood to be any radio engineering device designed to convert (both direct and reverse) electromagnetic (EM) energy of coupled waves into the energy of freely propagating EM waves (radio waves).

EMs include emitters of EM waves (sources of EM fields) that do not correspond either to traditional antenna construction schemes or to the conditions in which it is customary to determine their performance. According to [1-2], CAs are structurally included in the output cascades of transmitters and input cascades of receivers, are placed randomly in randomly inhomogeneous environments, are a combination of stationary and mobile-based modules, and are simply not available explicitly, for example, if about EM radiation of computer elements. Specific features of SA are the uncertainty of their geometric (number, size, spatial arrangement, orientation of elements, etc.) and electrical (radiation levels, number of radiation and reception channels, operating frequencies, etc.) characteristics. The task of experimental determination of the parameters of real multichannel SA is currently important for solving a number of applied problems related to ensuring electromagnetic compatibility and environmental safety of radio equipment for various purposes, protecting confidential information (CI) from leakage through EM channels in infocommunication networks [ 2-3], etc.

Known methods for determining the parameters of electronic means characterizing their mutual electromagnetic compatibility [4-8]. These methods include well-known methods for determining intermodulation (IM) characteristics [4-5], as well as the proposal to use IM channels for covert communication between subscribers using reflective surfaces with controlled parameters [8]. The methodological apparatus for assessing the effectiveness of non-linear radio communications and radio suppression is described in [9].

The closest in technical essence is a method for determining the levels of spurious EM emissions of the IM-type field [5, p.63-66, Fig.3.7] (prototype of the invention), including the following basic operations:

- the impact on the control transmitter with a frequency f _with EM radiation of an additional transmitter with a frequency f _∂ ;

- calibration and adjustment of the elements of the measuring path;

- calculation of the frequencies of the IM components f _u2 = | f _c ± f _∂ | second order; f _u3 = 2f _c ± f _∂ ; f _u3 = 2f _∂ ± f _{c of the} third order, and also, if necessary, of an arbitrary order f _i = | mf _c ± nf _∂ |, where m = 1; 2; 3 ...; n is 1; 2; 3 ...;

- measurement of power levels P _s (or voltage U _c ) of the signal generated at a frequency f _{with a} controlled transmitter at the input of the measuring receiver;

- measurement of power levels P _i (or voltage U _i ) of the IM components created at frequencies f _i at the input of the measuring receiver during the joint operation of the controlled and additional transmitters;

- calculation of the relative levels χ _them for signals (or recalculation for EM fields) for all IM components f _i = f _u2 ; f _u3 , ... | mf _c ± nf _∂ | taking into account the results of calibration and adjustment of the elements of the measuring path.

The main disadvantage of the prototype method is the impossibility of simultaneously identifying and evaluating with its help all possible channels of leakage of CI in SA arising from IM effects. In addition, the relative levels of the IM components of EM χ by _their emissions are determined here indirectly: by converting the values of power levels P _s and P _i (or voltages U _c and U _i ) at the frequencies f _s and f _{i of the} signals at the input of the measuring receiver, while it is preferable, from the point of view of reducing the measurement error, is a direct method for determining χ _them . Furthermore, in actual parser audio frequency f _c, audio block diagram of a controlled transmitter and its parameters are not known beforehand, and to connect and calibrate some elements of the measuring path, including measuring receiver directly to the CA (without which it is impossible to determine the values of χ _them via prototype method) is impossible.

The solution to the problem is, firstly, to make the frequency f _{∂ a} variable value using the oscillating frequency generator (ramp oscillator) connected to an additional transmitter and, secondly, to determine the χ values from _them direct measurement of EM radiation levels at frequencies f _s and f _i .

The technical result of the invention is to increase the accuracy and reliability of the results of determining the parameters of SA related to all channels of leakage KI, potentially possible in it. An additional result is to increase the efficiency of the process of determining the parameters of SA due to the possibility of its automation.

The essence of the proposed method for determining the parameters of a random antenna, including exposure to a random antenna emitting a signal with a frequency f _s , electromagnetic radiation of an additional transmitter with a frequency f _∂ ; calibration of the elements of the measuring path; calculation of the frequencies of the intermodulation components of the radiation of a random antenna f _i = | mf _c ± nf _∂ | where m = 1; 2; 3 ...; n is 1; 2; 3 ...; measuring power levels P _c (or voltage U _c ) of a signal generated at a frequency f _{with a} random antenna at the input of the measuring receiver; measuring power levels P _i (or voltage U _i ) of the intermodulation radiation components of a random antenna generated at frequencies f _i at the input of the measuring receiver during the joint operation of the controlled and additional transmitters, and calculating the relative levels χ _them for all intermodulation radiation components of a random antenna with frequencies f _i = | mf _c ± nf _∂ | according to the formulas

where K _c and K _i are the transmission coefficients for the power of the measuring path, respectively, at frequencies f _c and f _i ; consists in the fact that using the measuring receiver determines the unknown frequency f _{c of the} signal emitted by a random antenna; the minimum possible value of the frequency of the additional transmitter is calculated:

f _∂.min = f _c -f _min ; if f _c > f _∂

f _∂.min = f _c + f _min ; if f _∂ > f _c

and the maximum possible value of the frequency of the additional transmitter:

f _∂.max = (f _max -mf _c ) / n;

using the oscillating frequency generator connected to an additional transmitter, the frequency of external influence on a random antenna is _changed within f _∂.min ÷ f _∂.max and using a terminal device connected to the measuring receiver, the power flux density levels P ₀ and P _i are measured (or electric field strengths E ₀ and E _i ), respectively, at the frequencies f _c and f _{i of the} signals at the location of the measuring receiver; the relative levels χ of _the intermodulation components of the radiation of a random antenna are calculated by the formulas

and calibration of the elements of the measuring path is not performed.

Figure 1 shows the structural diagram of the hardware implementation of the prototype - a known method for determining the levels of spurious emissions of the IM-type field (see [5], p.63, Fig.3.7), where 1 is an additional transmitter; 2 - directional coupler; 3 - controlled transmitter; 4 - filter; 5 - attenuator; 6 - measuring receiver; 7 - shielded camera.

Figure 2 shows the structural diagram of the implementation of the proposed method for determining the parameters of CA, where 1 is an additional transmitter; 2 - oscillating frequency generator; 3 - investigated SA; 4 - measuring receiver; 5 - terminal device.

The proposed method is as follows.

In the known prototype method, at the first stage, the selected frequency f _{c is} set at the controlled transmitter 3 (see FIG. 1); on additional transmitter 1, the frequency f _∂ with a given detuning Δf = f _c -f _∂ (the sign and values of the detuning Δf determine the values of the IM frequencies of the second order f _u2 and third order f _u3 ). The measuring receiver 6 is tuned to the frequency f _c and the measurement path is calibrated, including a directional coupler 2, a filter 4 and an attenuator 5 located in the shielded chamber 7 (the calibration result is the power transmission coefficient at the frequency f _{c of the} measuring path K _s ). Then turn on the monitored transmitter 3 and at a frequency f _c measure the power P _c (or voltage U ₀ ) of the signal at the input of the measuring receiver 6, after which the monitored transmitter 3 is turned off.

At the second stage, the frequencies of the second-order IM components are determined:

f _u2 = f _c + f _∂ = 2f _∂ + Δf; f _u2 = f _c -f _∂ = Δf; if f _c > f _∂ ;

f _u2 = f _c + f _∂ = 2f _c + Δf; f _u2 = f _∂ -f _c = Δf; if f _∂ > f _c ;

and frequencies of IM components of the third order:

f _u3 = 2f _c + f _∂ = 2f _∂ + f _c + Δf; f _u3 = 2f _c -f _∂ = f _c + Δf; if f _c > f _∂ ;

f _u3 = 2f _∂ + f _c = 2f _c + f _∂ + Δf; f _u3 = 2f _∂ -f _c = f _∂ + Δf; if f _∂ > f _c .

At the frequencies of the IM components of the second order f _u2 and third order f _u3 , the measurement path is calibrated, including a directional coupler 2, filter 4 and attenuator 5 located in the shielded chamber 7 (the calibration result is the value of the power transfer coefficient by i -th frequency f _i where i = 1 ÷ 4, measuring path K _i ).

In the third stage include a controlled transmitter 3 at a frequency f _c and an additional transmitter 1 at a frequency f _∂ at the same time. The measuring receiver 6 is alternately tuned to the frequencies of the IM components f _i and each time the power P _i (or voltage U _i ) of the signal at the input of the measuring receiver 6 is measured, after which the relative levels of the IM components of the EM radiation χ _are calculated by the formulas

In relation to the conditions of the problem being solved - the study of the effectiveness of real SA - prototype method has the following disadvantages:

1. Any single value of the detuning Δf (any single value of the frequency of external influence on the SA (in the notation of the prototype is the frequency f _∂ )) is not enough to identify all possible channels of CI leakage into the SA arising from the IM effects.

2. The relative levels of the IM components of the EM radiation χ _they in the prototype are determined by recalculating the values of the power level P _s and P _i (or voltage U _c and U _i ) at the frequencies f _c and f _{i of the} signals at the input of the measuring receiver 6, taking into account the results preliminary calibration of the measuring path K _c , K _i , which is associated with an increase in the error in determining χ by _them (due to the influence of the measurement error of these values) in comparison with the determination of the value of χ by _them directly - according to the results of measuring the levels of EM radiation at frequencies f _c and f _i .

3. In the investigated SA it is fundamentally impossible to establish the necessary values of f _c ; connect and calibrate the elements of the measuring path (directional coupler, filter, attenuator); a measuring receiver connected directly to the CA, without which _they determine the value of χ using the prototype method is impossible.

Therefore, in this invention, it is proposed, firstly, to make the frequency f _{∂ a} variable that varies according to a previously known (linear) law and, secondly, to determine the values of χ by _them , according to the results of measuring the levels of electromagnetic radiation at frequencies f _c and f _i .

The proposed method for determining the parameters of the SA includes the impact on the SA emitting a signal with a frequency of f _c , EM radiation of an additional transmitter with a frequency of f _∂ ; calibration of the elements of the measuring path; calculation of the frequencies of the IM components of the radiation CA f _i = | mf _c ± nf _∂ |, where m = 1; 2; 3 ...; n is 1; 2; 3 ...; measuring power levels P _c (or voltage U _c ) of a signal generated at a frequency f _c CA at the input of the measuring receiver; measurement of power levels P _i (or voltage U _i ) of the IM components of SA radiation generated at frequencies f _i at the input of the measuring receiver during the joint operation of the controlled and additional transmitters and calculation of the relative levels χ _them for all IM components of SA radiation with frequencies f _i = | mf _c ± nf _∂ | according to the formulas

where K _with and K _i - the values of the transmission coefficients for the power of the measuring path, respectively, at frequencies f _c and f _i ; and differs from the prototype method in that an unknown frequency f _{c of the} signal emitted by the SA is determined using the measuring receiver; the minimum possible value of the frequency of the additional transmitter is calculated:

f _∂.min = f _c -f _min ; if f _c > f _∂

f _∂.min = f _c -f _min ; if f _∂ > f _c ,

and the maximum possible value of the frequency of the additional transmitter:

f _∂.max = (f _max -mf _c ) / n;

using the oscillating frequency generator connected to an additional transmitter, the frequency of external influence on the SA changes within f _∂.min ÷ f _∂.max and using the terminal device connected to the measuring receiver, the power flux density levels P ₀ and P _i are measured ( or electric field strengths E ₀ and E _i ), respectively, at the frequencies f _c and f _{i of the} signals at the location of the measuring receiver; the relative levels χ _{them of the} IM components of the radiation of a random antenna are calculated by the formulas

and calibration of the elements of the measuring path is not performed.

When implementing the proposed method at the first stage, using the measuring receiver 4 and the terminal device 5, the frequency f _{c of the} signal emitted by the CA 3 (see FIG. 2) is determined and, since the frequency band f _min ÷ f _{max of the} measuring receiver 4 is known, based on equalities

f _min = f _c -f _∂ ; if f _c > f _∂

f _min = f _∂ -f _c ; if f _∂ > f _c

determined by f _∂.min - the minimum possible value of the frequency of the additional transmitter 1:

f _∂.min = f _c -f _min ; if f _c > f _∂

f _∂.min = f _c -f _min ; if f _∂ > f _c

The maximum possible value of the frequency f _∂ is determined from the condition

f _max = mf _c + nf _∂ ,

whence follows

f _∂max = (f _max + mf _c ) / n.

At the second stage, using the oscillating frequency generator 2 connected to an additional transmitter 1, the frequency of external action on the CA 3 is _changed within f _∂.min ÷ f _∂.max . At the same time, using the terminal device 5 connected to the measuring receiver 4, the power flux density levels P ₀ and P _i (or electric field strength E ₀ and E _i ) are measured at the frequencies f _c and f _{i of the} signals at the location of the measuring receiver 4.

At the third stage, the relative levels of the IM components of EM radiation χ _{they are} calculated by the formulas

In contrast to the prototype, the proposed method, firstly, allows you to determine all the possible channels of CI leak in the SA, which can be detected in the strip

f _min ÷ f _{max of the} measuring receiver 4. Secondly, there is no need to calibrate the elements of the measuring path, because to determine χ _it uses the measured values of the power flux density P ₀ and P _i (or electric field strength E ₀ and E _i ) on frequencies f _c and f _i at the location of the measuring receiver 4, and not the power levels P ₀ and P _i (or voltage U ₀ and U _i ) of the signals in the measuring path of the receiver 4 (in the prototype, the receiver 6). Thirdly, the measuring receiver 4 and the terminal device 5 can be made in the form of a single device, for example, an analyzer of the frequency spectrum of a signal (manufactured by Rode & Schwarz and others) with a digital output. Fourthly, when the terminal device 5 is implemented in the form of a panoramic video indicator device, the result of the SA study can be obtained both in the form of a spectrogram - a graph of the frequency dependence of χ _im (f), and on all of its discrete points of interest χ _im (f _i ), which provides additional service amenities when interpreting the results.

The proposed method is universal, simple and effective, it is convenient for implementation and allows you to visually control the structure of the investigated EMP by visual analysis of spectrograms. Since the terminal device 5 may have a digital output for connecting a computer, the process of determining χ _them (f) and χ _them (f _i ) can be easily automated.

LITERATURE

1. Maslov O.N. Random antennas. // Telecommunications, 2006, No. 7, - S.12-15.

2. Kechiev L.N., Stepanov P.V. EMC and information security in telecommunication systems. M .: Publishing House "Technologies", 2005. - P.320.

3. Maslov ON, Shashenkov V.F. Information security: the aspect of electromagnetic compatibility and safety. // Bulletin of communication. 2005. No2. - S. 65-72.

4. Radio spectrum management and electromagnetic compatibility of radio systems. Ed. Bykhovsky M.A. M .: Eco-Trends, 2006 .-- 376 p.

5. Badalov A.L., Mikhailov A.S. Standards for the parameters of electromagnetic compatibility of RES. Directory. M .: Radio and communications, 1990 .-- 272 p.

6. Bubnov G.G., Nikulin S.M., Seryakov Yu.N. et al. Switching method for measuring PAR characteristics. M .: Radio and communications, 1988 .-- 120 p.

7. Voronin E.N., Shashenkov V.F. Microwave selective holography. M .: Radio and communications, 2003 .-- 535 p.

8. The method of radio communications and systems for its implementation. // Golovkov A.A., Volobuev A.G., Chaplygin A.A. et al. Patent RU 2271065 C1 of 06/09/2004, publ. 02/27/2006, bull. No. 6.

9. Aliev D.S., Avdeev V.B., Vaganov B.C., Vaganov M.S., Panychev S.N. Methodological apparatus for assessing the effectiveness of non-linear radio communications and radio suppression. // Telecommunications, No. 7, 2007. - S.35-40.

Claims (1)

A method for determining the parameters of a random antenna, including exposure to a random antenna emitting a signal with a frequency f _c , electromagnetic radiation of an additional transmitter with a frequency f _∂ , characterized in that an unknown frequency f _{c of the} signal is determined using a measuring receiver with a frequency band f _min ÷ f _max radiated by a random antenna; the minimum possible value of the frequency of the additional transmitter is calculated:
f _∂.min = f _c -f _min ; if f _c > f _∂ ;
f _∂.min = f _c + f _min ; if f _∂ > f _c ,
and the maximum possible value of the frequency of the additional transmitter:
f _∂.max = (f _max -mf _c ) / n,
where m = 1; 2; 3 ...; n is 1; 2: 3 ...; using the oscillating frequency generator connected to an additional transmitter, the frequency of external influence on a random antenna is _changed within f _∂.min ÷ f _∂.max and using a terminal device connected to the measuring receiver, the power flux density levels P ₀ and P _i are measured or electric field strengths E ₀ and E _i , respectively, at the frequencies f _c and f _{i of the} signals at the location of the measuring receiver; the relative levels χ of _the intermodulation components of the radiation of a random antenna are calculated by the formulas

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