RU2306578C1 - Method for determining electromagnetic signal source position - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: method involves determining center coordinates and estimating its location zone radius by applying statistical treatment (with mean and standard deviation being calculated) to mobile telephone positioning data in cases of communication disturbance caused by noise.

EFFECT: high accuracy in fixing cellular radiotelephone communication error sources.

4 dwg

Description

The invention relates to radio-technical means for determining the location of sources of electromagnetic signals, in particular emitters of both natural and interference jammers that disrupt the operation of electronic communications.

Known methods for determining the location of emitters of interference, such as lightning strikes, which are carried out by multi-point lightning systems. The structure of the latter includes geographically spaced receivers of a pulsed electromagnetic signal of a lightning discharge (atmosphere), analyzers of the form of the atmosphere as a function of time or direction finders [1] and special communication lines between them and the data processing center.

As an analogue of the invention, we take the differential-ranging method - the so-called TOA (TOA-Time-Of-Amval - arrival time) - a method for determining the location of lightning strikes [2], which are sources of interference. This method is based on determining the difference in the moments of time of receiving a pulsed atmospheric signal in at least three pairs of receiving points. This method consists in the fact that in each of the points a super-long-wave electromagnetic signal of the atmosphere is received by an omnidirectional electric antenna; amplify this signal in a wide frequency band; determine the time point of its reception. For each pair of receiving points, the difference in the times of reception of this signal by the receiving points is determined; this difference determines the difference in distances from these two points to the place of lightning strike; determine a hyperbolic positional line passing through the place of lightning strike; determine the place of atmospheric radiation as the intersection of two (at least two) hyperbolic positional lines. The atmospheric intake moment is considered the first of the atmospheric intake times at one of the receiving points.

The disadvantage of the analogue is the need to create a cumbersome expensive system of specialized reception points for determining the moments of time of reception of the atmosphere, as well as the creation of specialized communication lines and processing centers for the analysis of the received data.

The closest to the claimed technical solution adopted as a prototype is the TOA method for positioning mobile phones used in mobile cellular communication systems.

When positioning mobile phones, the following operations are carried out: determine the times of receiving the signal of the transmitter of the mobile phone in three (or more) base stations of the cellular communication network, the clocks of which are synchronized with each other; these data are transmitted to the localization center of mobile phones [3], in which the hyperbolic position lines of the position of the transmitter of the mobile phone are calculated by the difference in the moments of time of arrival of the signal at the base stations.

The disadvantage of the prototype is that it can establish the location of mobile phones, the operation of which is disturbed by interference, but does not directly establish the location of the source of interference to cellular communications.

The aim of the invention is to expand the functionality of the prototype method by providing the ability to determine the location of sources of electromagnetic signals that interfere with the cellular communication.

This goal is achieved by the fact that in the known method for determining the location of sources of electromagnetic signals, including

determination of time points for receiving a signal of a mobile phone transmitter in three (or more) base stations of a cellular communication network;

calculating the differences in the times of reception of this signal by base stations;

determination of hyperbolic positional lines corresponding to differences in the times of reception of this signal by base stations;

calculating the coordinates of the intersection point of these position lines,

according to the invention

fix time instants T of communication failures of any pair of cellular network subscribers and process them;

carry out the positioning of each of the two subscribers, between which communication was broken at time T;

fix the results of positioning X, Y of mobile phones, the communication with which was broken at time T;

form an array of current data T, X, Y, entering in it a point in time T and Cartesian coordinates X, Y of the subscriber’s position at time T, if the removal dRk = ((X-Xk) ² + (Y-Yk) ² ) ^{1 / 2} points (X, Y) from points (Xk, Yk) previously entered into the array of current data does not exceed Rmax for each k = 1,2, ... i-1; (if dRk> Rmax, then the values of T, X, Y are not taken into account. Rmax = 100 km from the weather data);

groups of values (T, X, Y) are numbered by indices i = 1, 2, 3, ... in the order of receipt of these groups of current data;

upon reaching a predetermined number n of fixed communication failures, the next group of values (T, X, Y) is assigned the number i = 1, the numbers of all other groups of values (T, X, Y) are increased by one, and the group of values (T _{n + 2} , X _{n + 2} , Y _{n + 2} ) are excluded from the array of current data;

calculate the average values Xj and Yj of the coordinates of the points (Xi, Yi), which are numbered by the index j = 1, 2, 3, ... in the order that these calculations are performed Xj = (Σ ⁿ _{i + 1} , Xi) / n, Yj = ( Σ ^m _{i + 1} Yi) / n;

determining the center of the location zone of the interference source as a point (Xj, Yj);

for each point (Xi, Yi) calculate its distance Ri = ((Xi-Xj) ² + (Yi-YJ) ² ) ^1/2 from the point (Xj, Yj). If it exceeds Rmax, then the numbers Xi and Yi are excluded from consideration and replaced by the numbers Xj and Yj;

give a root-mean-square estimate of the radius Rj = ((Σ ⁿ _{i + 1} Ri ² ) / n) ^{l / 2 of} the location zone of the interference source.

New in the proposed method for determining the location of sources of electromagnetic signals in comparison with the prototype are additional operations for fixing the time instants of communication disruption and fixing the location of subscribers with whom communication was disrupted at these moments, and processing of this data, which allows to establish the center and radius of the affected area of the cellular communication system .

The drawing shows an example of the ratio of the places of lightning strikes (x) of the positioning results (o) of subscribers with whom communication was broken due to a thunderstorm, as well as the radius r max, the center (Xj, Yj) and the radius Rj of the communication failure region.

Sources of electromagnetic waves are divided by their origin into natural and man-made. Of the natural sources of radiation, thunderstorm foci are of most interest. A thunderstorm hearth is a dangerous natural phenomenon - an area within which discharges of atmospheric electricity occur. It takes up a lot of space and time.

Its large extent in space allows you not to require high accuracy in determining the boundaries of a thunderstorm. Its great length in time - the duration of a thunderstorm - allows you to accumulate a lot of factual material about the nucleation, movement and attenuation of a thunderstorm during a thunderstorm and process this material in a natural time scale.

The fact that there was a discharge of atmospheric electricity is judged by its consequences:

acoustic signal (thunder),

light signal (flash of lightning),

electrical (lightning strike),

electromagnetic signal (atmospherics).

The last two of these consequences are fraught with danger to humans, and their manifestations are detrimental to the national economy.

A lightning strike causes a forest fire, incapacitates power lines. A lightning strike on an aircraft leads to severe emergency consequences. The atmospheric electromagnetic pulse disrupts the operation of electronic equipment. Therefore, the location of lightning centers and tracking their movement is necessary for civil aviation, the forest protection service from fires and the protection of power lines from lightning damage.

Currently, the location of lightning strikes, forming a thunderstorm, is carried out by multi-point lightning location systems. The latter includes geographically spaced receivers of a pulsed electromagnetic signal of a lightning discharge (atmosphere), analyzers of the form of the atmosphere as a function of time or direction finders, as well as special communication lines between them and data processing centers.

It is of interest to create such lightning location systems for which neither the creation of a system for receiving atmospheres or direction finders, nor specialized communication lines, nor the construction of special data processing centers would be required.

The solution to this problem becomes possible by using the standard means of the rapidly developing mobile cellular communication systems that provide their subscribers with a wide range of diverse services.

The concept of a thunderstorm source is formed on the basis of an analysis of the aggregate information about the places and time instants of a certain number of lightning strikes. The concept of a thunderstorm is intuitively clear. But let us give a formal definition: a thunderstorm center is a closed region of three-dimensional space, the surface of the earth - the time within which discharges of atmospheric electricity occur.

Powerful discharges of atmospheric electricity near the mobile phone violate the synchronism of the mobile phone with the nearest cellular base station. This circumstance allows us to judge that within the cell or outside it, but close to it, a lightning strike occurred, and when exactly. The fact and moment of communication failure between a pair of subscribers is always fixed by regular means of cellular communication.

Positioning of subscribers between whom communication was interrupted for a while, i.e. location of the ends of the broken communication line can also be fixed by the cellular communication system [3].

The accumulation of this information during a thunderstorm and their statistical processing makes it possible to clarify the location of a thunderstorm source that caused disruptions in cellular communications.

Therefore, instead of information about the place and moment of a lightning strike, you can use information about the location of subscribers whose communication was disrupted due to a thunderstorm, and about the time of a communication failure.

In the case of electromagnetic radiation of technogenic origin, the situation is similar to that that arises when atmospheric radiation is emitted by a thunderstorm. In both cases, electromagnetic radiation interferes with the operation of electronic equipment.

Fixing the places of disruption of electronic equipment allows you to identify the area of influence of the source of electromagnetic interference, in this case of technogenic origin, for example, the jammer. These violations can be no less serious than those generated by a thunderstorm.

Determining the center and radius of the interference source by the same rules as the center and radius of the thunderstorm, we determine the center and radius of the zone within which the desired technogenic source of electromagnetic radiation is located.

A mobile phone is always connected to several base stations closest to it so as not to lose contact with them when moving from one cell to another. As a result, the location of the mobile phone with which the network is in communication is always known in the computing center of the cellular network. To ensure the operation of the transmitter, tacit remote activation of a mobile phone can be performed [3].

The fact of communication failure is used as an indicator that there has been interference radiation.

Regular means of cellular communication is recorded as the fact of a communication failure for some time, and the moment of communication failure between a pair of subscribers. In addition, the positioning of each of the subscribers between whom communication was interrupted, i.e. location of the ends of the broken communication line. This information is always available from the cellular dispatch service.

Therefore, instead of information about the place and moment of emission of interference, you can use information about the location of pairs of subscribers, the cellular communication between which was disturbed by the interference, and about the moment of communication failure between this pair of subscribers. The admissibility of such a replacement is justified experimentally.

The proposed method includes the following sequence of operations:

1. Fix the time moment T of the synchronism violation in the operation of the cellular communication line of any pair of subscribers.

2. Positioning of these subscribers is carried out (if the subscriber is outside the intended boundaries of the zone of search for the source of interference, then the result of positioning of this subscriber is ignored, that is, not used in any way).

3. The time moment T and the Cartesian coordinates X, Y of the positioning of the subscribers (subscriber) at the moment T are entered into the current data array if the distances dRk = ((X-Xk) ² + (Y-Yk) ² ) ^1/2 points (X , Y) from the points (Xk, Yk) previously entered and the array of current data do not exceed Rmax for each k = 1, 2, ... i-1. The groups of values (T, X, Y) are numbered by the index i = 1, 2, 3, ... in the order of entering these groups into the array of current data; (if dRk> Rmax, then the values of T, X, Y are not taken into account).

4. Upon reaching a certain predetermined number n of fixed synchronization violations, the next group of values (T, X, Y) is assigned the number i = 1, all other numbers of the values T, X, Y are increased by one, and the group of values (T _{n + 2} , X _{n + 2} , Y _{n + 2} ) are excluded from the array of current data.

5. Calculate the average values Xj, Yj of the coordinates of the points (Xi, Yi), which are numbered by the index j = 1, 2, 3, ... in the order that these calculations are performed Xj = (Σ ⁿ _{i + 1} Xi) / n, Yj = (Σ ⁿ _{i + 1} Yi) / n, and determine the center of the zone of location of the interference source as a point (Xj, Yj).

6. For each point (Xi, Yi) calculate its distance Ri = ((Xi-Xj) ² + (Yi-Yj) ² ) ^1/2 from the point (Xj, Yj), and if it exceeds Rmax, then the numbers Xi and Yi are excluded from the consideration and replaced by the numbers Xj and Yj.

7. A root mean square estimate is given of the radius of the area where the source of interference is located Rj = ((Σ ⁿ _{i + 1} Ri ² ) / n) ^1/2 .

An example of the implementation of the proposed method for locating a source of interference to a cellular communication is the location of a thunderstorm source as a natural source of interference to a cellular communication.

During the thunderstorm season of 2004, the operation of the MTS cellular mobile communication system in thunderstorms was monitored in the Moscow Region. It was believed that communication disruptions were caused by disruptions in the operation of mobile phones, and not between the base stations, because these stations are equipped with more powerful transmitting and more protected from interference jamming equipment than a mobile phone, and it is possible to find a workaround bypassing the damaged area.

It was found that a powerful thunderstorm center, creating a stream of atmospheres with a density of at least 3 imp. / Min, causes a violation of the synchronism of the mobile phone with the cellular communication point after each lightning strike, which is visually recorded.

Violation of synchronism was evidenced by a characteristic short hissing listened to on a mobile phone and lasting less than a second, during which the synchronization restoration process is going on.

The distance r between the mobile phone with which the connection was lost and the place of the lightning strike was determined by the delay of the acoustic signal of the lightning discharge relative to the optical one, based on the ratio of 1 km - 3 sec. Differences of more than r max = 10 km between the places of lightning strikes and the location of the mobile phone, which was known, were not observed. These differences are smaller than the typical sizes of thunderstorm outbreaks, and neglect of these differences does not introduce a significant error in the location of thunder outbreaks (see drawing).

The sizes of thunderstorm outbreaks depend on their origin. Thunderstorms are either thermal or frontal. The overall dimensions of 2Rmax of thunderstorm foci of thermal origin reach several tens or a hundred kilometers. The length of thunderstorm foci of frontal origin reaches several hundred kilometers, and the diameter is also several tens or a hundred kilometers.

When implementing the proposed method for determining the location of interference sources, installation of additional equipment is not required in comparison with the standard equipment of mobile cellular communication.

The technical result of the proposed method in comparison with the prototype is to expand the functionality of mobile cellular communications by providing the ability to determine the location of interference sources, in particular lightning discharges, without additional costs for expensive equipment and, in addition, in highlighting the area of communication disruption.

Information sources

1. Mahotkin L.G., Astashenko A.I. Physical foundations of methods for direction finding of thunderclouds and their technical implementation // Proceedings of the State Civil Defense Organization, 1965, issue 177.

2. Casper P.W. The LPATS Time of Arrival Lightning Positioning System // Proc. 20-th Int. Conf. on Lightning Protection Sep 24-29 1994, Interlaken, Switzerland.

3. Ryzhikov S.S., Ryzhikov A.S. Overview of modern systems for positioning mobile phones // Special equipment, No. 6, 2001, p. 28-36.

Claims (1)

A method for determining the location of sources of electromagnetic signals, including determining the timing of reception of a signal from a mobile phone transmitter in three or more base stations of a cellular communication network, calculating differences in timing of reception of this signal by base stations, determining hyperbolic position lines corresponding to the calculated timing differences of receiving this signal by base stations, calculating the coordinates of the intersection point of these hyperbolic positional lines, characterized in that fix the time moments T of communication failures of any pair of subscribers of the mobile cellular communication network, carry out the positioning of each of the two subscribers between whom communication was lost at time T, record the results of positioning X, Y of mobile phones, the communication with which was broken at time T , form an array of current data T, X, Y, entering in it a point in time T and Cartesian coordinates X, Y of the positioning of these subscribers at time T, if the removal Rk = ((X-Xk) ² + (Y-Yk) ² ) ^1/2 point (X, Y) of points (Xk, Yk), previously listed in Assuming current data does not exceed Rmax for each k = 1, 2, ..., i-1, where Rmax = 100 km, groups of values (T, X, Y) are numbered by indices i = 1, 2, 3, .. .in the order of receipt of these groups of current data, upon reaching a predetermined number n of fixed communication failures, the next group of values (T, X, Y) is assigned the number i = 1, the numbers of all other groups of values (T, X, Y) are increased by one, and the group of values (T _{n + 1} , X _{n + 1} , Y _{n + 1} ) is excluded from the current data array, the average values of the coordinates Xj and Yj of the coordinates of the points (Xi, Yi) are calculated, which are numbered by the index j = 1, 2, 3, ... in the exercise of These calculations Xj = (Σ ⁿ _{i + 1} , Xi) / n, Yj = (Σ ⁿ _{i + 1} Yi) / n, determine the center of the zone of location of the interference source as a point (Xj, Yj), for each point (Xi, Yi) calculate its distance Ri = ((Xi-Xj) + (Yi-YJ) ² ) ^1/2 from the point (Xj, Yj), if it exceeds Rmax, then the numbers Xi and Yi are excluded from consideration and replaced by the numbers Xj and Yj, give a root mean square estimate of the radius Rj = ((Σ ⁿ _{i + 1} Ri ² / n) ^{1/2 of} the location zone of the interference source.