RU2495527C1 - Jamming method and device - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: resultant interfering signal is generated in a given region and eigen coordinates are measured. Composition of the orbital group of the global navigation satellite system used in the region and the number of properly functioning satellites are determined, while simultaneously receiving signals with navigation messages transmitted by the properly functioning satellites for all users of the global navigation satellite system in the region. The received messages are stored; navigation messages therein are distorted, after which a resultant interfering signal is generated in form of a plurality of signals with distorted navigation messages; the resultant interfering signal is synchronised with signals of navigation messages of satellites of the global navigation satellite system; the resultant interfering signal is emitted with power higher than that of legitimate signals of the satellites of the global navigation satellite system, wherein during prolonged operation, stored navigation messages are periodically updated.

EFFECT: concealed distortion of navigation parameters for radio navigators of a group of users located in a spatially limited but known region.

2 cl, 12 dwg

Description

The inventive object relates to radio engineering and is intended to create artificial interference, in particular to distort the navigation field to a group of users in a given area.

A known method of creating simulated interference (see. Paly A.I. Electronic warfare. (Means and methods of suppressing and protecting electronic systems). - M.: Military Publishing, 1981, p. 50-55).

An analogous method includes receiving a signal from a radio source at a frequency f _s , delaying a received signal for a time Δt _s , generating a carrier wave f _n at the frequency of the received signal, generating a jamming signal by modulating the carrier wave with a delayed received signal, amplifying the output jamming signal and its radiation.

The analogue allows you to create effective interference to digital communication networks operating in simplex (at the same frequency of reception and transmission) mode. The advantages of the method include a lower average interference power and power consumption of the transmitter. However, the analogue method has a significant drawback: there is no possibility of creating effective interference with the radio navigators of the user group of the global navigation satellite system (GNSS).

The formation of a sufficiently powerful barrage interference (in the emission spectrum of GNSS satellites) will lead to the fact that the latter will be detected by users upon the inoperability of the navigation system. In addition, this approach will require significantly higher energy costs.

The closest in technical essence to the claimed is a method of radio suppression of communication channels according to the patent of the Russian Federation No. 2229198, IPC Н04К 3/00, publ. 05/20/2004, bull. Number 14.

The prototype method includes the simultaneous reception in a given area of the signals of all users, the formation of the carrier oscillation from the condition

$$f_n={\overline{f}}_c-\Delta f_i,$$

- среднее значение частоты группового спектра базовой станции, формируют суммарный помеховый сигнал путем модулирования несущего колебания принятыми сигналами.where Δf _i is the separation between the i-th frequency of the base station and the i-th frequency of the mobile subscriber of the duplex communication channel, i = 1, 2, ..., N, N is the number of frequency channels in the standard of a cellular communication system, $${\overline{f}}_c$$

- the average value of the frequency of the group spectrum of the base station, form the total interference signal by modulating the carrier wave with the received signals.

The prototype method provides suppression of a group of channels of subscribers with unknown numbers located in a spatially limited but well-known area, with the involvement of the minimum material and energy resources. By the nature of the impact, the method provides the formation of imitating (misinforming) interference, which serve to introduce false information into suppressed means (see Paly A.I. Electronic warfare: (Means and methods of suppressing and protecting electronic systems). - M.: Military Publishing, 1981 pg. 10-11); Vladimirov V.I. The methodology of designing complexes of REP and their components. - Voronezh, VVIURE, pp. 40-46). The method can significantly reduce the average interference power and power consumption of the transmitter. However, the prototype method also has a disadvantage associated with the lack of the ability to create effective interference with the radio navigators of a group of GNSS users located in a spatially limited but known area.

The aim of this invention is to develop a method for creating intentional interference, providing a hidden distortion of navigation parameters for radio navigators of a group of GNSS users located in a spatially limited, but known area.

This goal is achieved by the fact that in the known method of creating deliberate interference, including the formation in a given area of all users of the total interference signal, measure the coordinates of their own location. Next, determine the composition of the GNSS orbital group used in the area, and the numbers of operable satellites from among them. At the same time, they receive navigation messages transmitted by operable satellites for all GNSS users in a given area. Remember the received messages. The navigation messages are distorted in them, after which a total interference signal is formed in the form of a set of signals with distorted navigation messages. The total interfering signal is synchronized with the signals of navigation messages of GNSS satellites, the total interfering signal with a power exceeding the power of the legitimate signals of GNSS satellites is emitted, and during long-term operation, previously stored navigation messages are periodically updated.

Navigation messages are distorted by delaying them at different time intervals.

The listed new set of essential features due to the fact that the total interference signal is synchronized with the navigation messages of GNSS satellites, and the modulating interference voltage is formed as a group signal consisting of distorted navigation messages of operable satellites, which allows to achieve the purpose of the invention: to provide hidden distortion of navigation parameters for radio navigators user groups located in a spatially limited but well-known area.

The inventive method is illustrated by drawings, in which

figure 1 shows the use of the claimed objects:

a) territory without distortion of the navigation field;

b) territory with a distortion of the navigation field;

figure 2 illustrates the structure transmitted by GNSS satellites messages:

a) the structure of the transmitted frame;

b) the structure of the transmitted subframe;

figure 3 shows a generalized distortion algorithm of the navigation field;

figure 4 shows a structural diagram of a device for creating intentional interference;

figure 5 shows an embodiment of the device used during practical tests.

One of the promising directions for solving the problem of the information blockade of GNSS users in a spatially limited area is the formation of imitation interference. Their use provides stealth effects on radio navigators and does not require significant energy and material costs. Using the proposed method distort navigation messages in a certain area, the parameters of which differ from the true ones. As a result of this, it will be impossible for outsiders to determine the true coordinates of the objects in the given territory. Outside the coverage area of the claimed objects, the navigation field remains legitimate.

Suppose that it is necessary for buildings No. 2 and No. 3 (see figa) to change the coordinates to close, but incorrect, while maintaining the true coordinates of building No. 1.

In the absence of distortion of the navigation field, each of these structures has its own coordinates.

As a result of the impact of the claimed objects on the navigation receivers, the latter will show the coordinates specified by the operator. On figb it is shown that the radio navigators located in the shaded area (the zone of accessibility of imitation interference) will work correctly, but at the same time fix false (specified by the operator) coordinates.

It is known that GNSS-based navigation systems have a very complex time-frequency structure of airborne interfaces (see Shebshaevich V.S. et al. Network Satellite Radio Navigation Systems. - M.: Radio and Communications, 1993).

GNSS navigation messages contain operational and non-operational navigation information (see figure 2). The operational information refers to the satellite from which the navigation radio signal is transmitted, and consists of the spacecraft ephemeris (predicted coordinates and satellite motion parameters at a fixed point in time).

Non-operational information contains the almanac of the system (a set of approximate satellite data) used to calculate the approximate location of the satellite, time of its appearance above the horizon, elevation and azimuth. The almanac is used by the receiver to capture satellite signals, as well as in the planning process of observation sessions. The almanac contains data on the state of all the spacecraft of the system (state almanac), the shift of the time scale of each satellite relative to the time scale of the system (phase almanac), approximate parameters of the orbits of all the satellites of the system (almanac of orbits), etc.

Unlike the almanac, ephemeris have much higher accuracy, and they are used in a navigation solution. Each spacecraft transmits only its own ephemeris. Their life time is several hours, while the relevance of the almanac is 2-3 months.

At any point on the Earth (except for the polar regions), signals from 8-10 KA can be simultaneously received (out of 32). The BPSK KA signals are modulated by individual SRPs called rangefinder codes. Therefore, to measure the phase difference of the signals, it is first necessary to remove the a priori known modulation of the SRP, to take into account the Doppler frequency shift and the signal delay during its propagation.

The structural division of the navigation information of the satellite of the GPS system is carried out on pages, frames, subframes and words (see Fig. 2a, b). Pages consist of 25 frames, and its transfer takes 750 s (12.5 min). One frame is transmitted for 30 s and contains 1,500 bits of information. Each subframe contains 10 words of 30 bits. The first word of each subframe contains the preamble, and the second is the system time. In the first three subframes, operational information is transmitted: data on the clock correction parameters and data of the spacecraft ephemeris.

Under these conditions, the optimized interference effect involves determining your own location, the composition of the GNSS orbital group available in this region, determining the numbers of satellites on behalf of which the interference signal will be generated, determining the coordinates of a point in space or on the earth’s surface where GNSS users are supposed to be , recalculation of the coordinates of this point in the navigation messages of the spacecraft, entering synchronism with operable GNSS spacecraft, the formation and emission of an interfering signal and in the form of navigation messages on behalf of the GNSS satellite (see figure 3).

Consider in more detail the proposed method of creating intentional interference, which involves the following. At the preparatory stage, the boundaries of the area of distortion of the navigation field are determined. Next, determine the appropriate location of the source of optimized interference, taking into account the terrain, urban development, etc. Depending on the size of a given area, taking into account local conditions, the source of interference can be placed both on the earth's surface in the center of a given area or object, and on the roof of an object or neighboring building, on an unmanned aerial vehicle, helicopter, etc. Given the considerable size of a given area, it is advisable to place a deliberate jamming device on a flight-lifting device, for example, an Orlan-10 unmanned aerial vehicle (UAV) (see the All-Russian Aerospace Journal Vestnik Aviation and Cosmonautics; No. 3, 2010; http: //bla-orlan.ru). After that, the location coordinates of the jamming station are determined.

For the correct substitution of navigation parameters, it is further necessary to analyze the electronic environment (REO), to determine the composition of the GNSS orbital group. Information is collected about all the satellites that are currently “visible” in a given area. If the conditions for receiving spacecraft navigation messages are unsatisfactory (less than three spacecraft are observed), there is no need for further system operation. Otherwise (in the case of a satisfactory REO), the ephemeris of all the spacecraft and the almanac are administered. This operation takes about 15 minutes. The accepted value of the almanac is maintained until the end of the day according to international time and is used unchanged when the system is restarted. On its basis, the composition of the orbital constellation and satellite numbers are determined.

At the next stage, the coordinates of the point to be obtained by GNSS users located in a given area (regardless of their true location) are set. Removing a simulated point from a real one should not be so significant as not to arouse suspicion of users of the system.

It is known that radio navigators measure propagation delays of signals from each of the “visible” satellites, the coordinates of which are a priori known. These delays are the source data for determining the coordinates of the user. Knowing the coordinates that a GPS user should receive, they calculate signal delays for all “visible” satellites. As a result, all receivers receiving this total signal will receive the same navigation solution, regardless of their own location. By adjusting the mutual delays of the spacecraft signals, it is possible to control the navigation solution at the same time for all receivers located in a given area. Based on the results of the REO analysis (the composition of the orbital constellation and spacecraft numbers), the calculated necessary initial delays of the signals of each satellite, complete navigation messages are generated for all “visible” spacecraft. The latter is remembered and subsequently used in the formation of the total simulation interference signal.

At the final stage of formation of the total interfering signal, standard operations are performed: amplification and its radiation. It should be noted that the generated total interfering signal is emitted synchronously with the emissions of the legitimate GNSS constellation, which reduces the time it takes the user receiver to switch from a real navigation field to a substitute one. With similar characteristics of the navigation fields, the substitution is invisible to the user. Due to the fact that the creation of radio interference to GNSS subscribers is implemented in close proximity to them, the power of the interfering signal R _P can be fractions and units of watts.

During operation, the mutual delays of the spacecraft signals are adjusted. This operation is carried out by measuring the delay between the simulated and reference signals for each GNSS satellite. The latter is equivalent to measuring the distance over which the corresponding satellite actually moved during operation. According to the results of the analysis, the navigation messages used in further work are adjusted.

Analysis of the effectiveness of the proposed method compared with the classical approaches to solving the problem showed that its main advantages are:

the possibility of hidden distortion of navigation parameters for navigators of a group of GNSS users located in a spatially limited but well-known area;

full consistency of the structure of radio interference and legitimate GNSS signals;

minimum energy consumption for the creation of intentional interference;

structural and structural simplicity of the method.

Figure 4 shows the structural diagram of a device for creating intentional interference that implements the inventive method. The device contains receiving 7 and betraying 6 paths, series-connected reference oscillator 10 and amplifier 9, high-speed comparator 8, path for calculating pseudo-parameters of orbital constellation 2, N paths for generating signals from spacecraft 3.1-3.N, adder 4 and digital-to-analog converter 5. Calculation path the pseudo-parameters of the orbital constellation 2 is provided with an installation bus 1, the information input and the output synchronization bus of which are connected respectively to the output of the receiving path 7 and the group of control inputs high-speed comparator 8. The output of block 8 is connected to the synchronization inputs of N paths for generating the signals of KA 3.1-3N, adder 4, digital-to-analog converter 5 and the path for calculating pseudo-parameters of orbital grouping 2, the nth group of information outputs of which, where n = 1, 2, ... , N, is connected to the group of information inputs of the nth path of the formation of signals of spacecraft 3.n. The first and second groups of information outputs of paths 3.1-3.N are connected to the corresponding groups of information inputs of adder 4. The first and second groups of information outputs of block 4 are connected to the corresponding groups of information inputs of the digital-analog converter 5, the output of which is connected to the first information input of the transmitting path 6. The second information input of the transmitting path 6 is combined with the information input of the receiving path 7, the input of the high-speed comparator 8 and connected to the output of the amplifier 9.

The operation of the device is as follows. At the preparatory stage, the boundaries of the area in which the distortion of navigation parameters (navigation field) will be implemented are determined. Depending on its size, as well as taking into account the terrain, the presence of industrial or other buildings, etc. determine the location of the device to create intentional interference (on the ground, the roof of buildings, UAVs, etc.). Then, along the bus 1 (see Fig. 4), a simulation task is introduced into the calculation path of the pseudo-parameters of the orbital group 2, which includes the start and end times of the device and the coordinates to be simulated.

At the same time, using the receiving path 7 and block 2, the GNSS spacecraft signals are received and the REO analysis is based on them: the number of operational GNSS spacecraft that are "visible" at a given time is determined and their numbers are determined. This information is isolated from the ephemeris of the spacecraft and almanac adopted using paths 7 and 2. Reception of the almanac is 15 minutes. Further, the values of the ephemeris and almanac are stored in the non-volatile memory of path 2. At the same time, the almanac is stored until the end of the current day (international time) and when the inventive device is turned on again, it is loaded from it. Ephemeris values are updated as information ages. If 1-2 spacecraft (unsatisfactory REO) are noted in the work, the proposed device does not need to work. In case of detection of three or more operational spacecraft, the device (paths 2 and 3) proceed to the formation of navigation messages on their behalf.

The functions of path 2 include the calculation of the necessary delays of navigation messages for all operational spacecraft. In addition, using blocks 2, 3, 8, and 10, the internal time of the device is synchronized with the time of the navigation system. As a result, from N 'groups of outputs of the path for calculating the pseudo-parameters of the orbital group 2, where N' is the current number of operational spacecraft, N '= 3, 4, ..., N, the corresponding initial data (spacecraft number, required delay of its signals, as well as almanacs and the corresponding ephemeris values) for each path of formation of the signals of the spacecraft 3.1-3.N '. On their basis, paths 3 form the required complete navigation messages. Each of the paths 3 is configured to work on behalf of a particular satellite, and as necessary, navigation messages are generated at its output. To set and adjust the delays between the signals of the satellites in paths 3 introduced feedback between the signals of the simulated satellite and the reference signal. The latter are the signals of the reference generator 10 and the high-speed comparator 8, which perform the function of a single time standard in the proposed device.

The navigation messages generated by paths 3 arrive at the corresponding input groups of the adder 4. Its function includes combining all generated navigation messages, which then go to the input of the digital-to-analog converter 5. Next, the analog total interference signal follows the input of the transmitting path 6. The functions of the latter include signal transfer to the carrier frequency L1 = 1575.42 MHz, amplification to the required level and radiation to the ether.

In order to increase the speed of the device, reduce the overall dimensions and power consumption, increase its reliability, it is advisable to implement blocks 2, 3, and 4 (see Fig. 5) on a digital processing processor DSP TMS320c6455 (see http://www.compel.ru) in conjunction with the Virtex XC4SX35 FPGA chip (blocks 1 and 5, 6) (see ibid.). In this case, all processing is performed digitally in a single specialized digital processor. A signal is supplied to the digital-to-analog converter, which fully corresponds to the structure of the simulated navigation field. Moreover, to synchronize the operation of the elements of the entire device, only one reference generator is sufficient. All necessary internal frequencies are realized using the operation of resampling the signals to the base reference frequency. Such a construction seriously reduces the cost of the hardware due to some complication of the software.

A mock device was made in accordance with the claimed method of the invention and its practical tests were carried out. The device is made in accordance with figure 5 and was placed on an Orlan-10 UAV. The Garmin Oregon 450 tourist navigator was used as a control subscriber terminal. Tests were carried out on medium-rough terrain. The latter showed that at a flight altitude of Orlan-10 2 km, a guaranteed distortion of the navigation field in the territory with a radius of 2.5 km is provided.

Claims (2)

1. The method of creating deliberate interference, which consists in the fact that in a given area they form a total interference signal, characterized in that they measure the coordinates of their own location, determine the composition of the orbital constellation of the global navigation satellite system (GNSS) used in this area, and the numbers of operable from their number of satellites, simultaneously receive signals with navigation messages transmitted by operable satellites for all GNSS users in a given area, remember received e messages distort navigation messages in them, after which they form a total interference signal in the form of a set of signals with distorted navigation messages, synchronize the total interference signal with the navigation messages of GNSS satellites, emit a total interference signal with a power exceeding the power of legitimate signals of GNSS satellites, during prolonged use periodically update previously stored navigation messages. 2. The method according to claim 1, characterized in that the navigation messages are distorted by delaying them at different time intervals.

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