RU2818300C1 - Method of protecting radio transmitters from direction finding - Google Patents

Abstract

FIELD: modulation methods and devices.

SUBSTANCE: invention relates to methods of protecting radio transmitters (RT) from detection of their location by direction-finding devices (DFD). Disclosed method consists in matched fast-variable quasi-coherent emission of signals by several RTs, which are controlled by a controller and create, in combination, a variable nonlinear structure of the wave front near the DFD. Main difference of the proposed method is that all connected radio transmitting stations continuously transmit information on one common carrier frequency, and the controller over the local area network randomly addresses transmitted frames to each of the stations, which, when receiving frames, perform carrier modulation at different times.

EFFECT: reducing the probability of determining the coordinates of the RT due to the fact that the DFD is not able to determine the actual positions of radiation sources in a short time.

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Description

The invention relates to methods for protecting radio transmitters (RP) from detection of their location by direction-finding devices (DF), and consists of coordinated, rapidly variable quasi-coherent emission of signals by several RF, controlled by a controller and collectively creating a changing nonlinear structure of the wave front near the PU.

The achieved technical result of the proposed invention is to reduce the probability of determining the coordinates of the RP due to the fact that the PU is not able to determine the actual positions of the radiation sources in a short time.

There are various ways to combat PU.

A passive method is known, which uses a displacement of the guidance point of an anti-radar missile away from the suppressed radar station (radar). This shift is ensured through the use of additional radiation sources (ADS) and various types of re-reflectors [1]. There is also a known method that uses several (N) additional radiation sources made in the form of transmitters with antennas [2]. Such transmitters can be coherent or incoherent. Various active methods for protecting radars are known [3-10]. There is a known method of protecting radars from anti-radar missiles [11], chosen as a prototype and consisting in the fact that N DIIs are used to protect the radars. In this case, the DIIs are located from the protected radar station at distances not less than the damage radius and not greater than the line-of-sight distance of the protected radar. Control of the time and frequency parameters of the DII must be provided by the leading radar. In this case, the period of emission of distracting signals of the DII must be less than the constant of the control loop of the PU.

The total signal received by the PU creates the illusion of a certain phase center, the location of which is different from the location of the protected radar.

The purpose of the present invention is to protect short-wave RP from their direction finding using PU (installed, for example, on unmanned aerial vehicles (UAVs)).

The technical result to which this invention is aimed is the creation of a method for protecting short-wave radio transmitting stations (RPS) from reconnaissance UAVs with on-board direction finders (direction finding devices) installed on them due to the coordinated quasi-coherent emission of signals simultaneously by several RPs controlled via a local area network (LAN). ) using a controller and collectively creating a changing nonlinear structure of the wave front near the launcher, which is not able to determine the actual positions of the radiation sources in a short time. As a result, the likelihood of determining their coordinates will be sharply reduced.

The essence of the claimed invention is that a method is proposed for protecting the radar from direction finding, which consists in the fact that information is transmitted at one frequency alternately by several radios, which are spaced apart and located relative to each other at a distance of at least 3-5 km. At the same time, the claimed method differs from the known one in that instead of distracting signal sources, the RPs themselves are used, controlled by a controller via a LAN.

To expand the range of local radio LANs operating in the ultra-short wave (VHF) frequency range (for example, Wi-Fi), one of the LAN nodes is connected to a short-wave radio transmitting station (RSS), as shown in Figure 1.

Shortwave RPS.

LAN node.

Subscribers of LAN-2 nodes exchange information, and part of the information enters the short-wave radio transmitter of the RPS-1 station, which can be easily direction-finded.

Several RPSs can be connected to the LAN, as shown in Fig. 2.

Connected RPSs operate in different frequency ranges so as not to interfere with each other's transmissions. Such RPS are also easy to find and their coordinates are determined.

The main difference of the proposed method is that all connected RPSs continuously transmit information on one common carrier frequency.

The system works as follows:

Subscribers to a LAN (or radio LAN) communicate with each other directly over the LAN. Part of the information in the form of frames to be transmitted through the RPS is sent by subscribers to the root node containing the control controller-3. Controller-3 randomly addresses incoming frames in turn to each of the RPSs, which transmits them on the air. The functions of the controller can be assumed by any of the network nodes, including those nodes that are directly located on the RPS. The controller periodically checks the readiness of the RPS for transmission over the network and, if it is not ready, excludes it from the frame addressing cycle. The cycle for checking the readiness of the RPS does not exceed 1 second. It is believed that during the specified time interval the probability of loss of readiness of the ready-to-work RPS is very small. Since Controller-3 is constantly informed about the readiness of the RPS to receive and transmit information, it immediately sends a frame (or group of frames) to the next RPS, and then waits for it to confirm the end of the transmission of the frames it has received. After receiving confirmation, the controller randomly selects the next RPS and addresses the frame to it for transmission. For example, with a frame length of 1 kilobyte and a transfer rate of 10 megabits per second, the transmission time of one frame is 0.8 milliseconds. This is the minimum possible time between the transmission of two adjacent frames. In a particular case, a LAN can consist only of nodes directly connected to the RPS. The controller node synchronizes the operation of the RP over the network and maintains equality of the carrier frequencies of the RP.

It should be noted that during the absence of useful information transmission (no carrier modulation), stations may not stop transmitting the carrier.

LITERATURE:

Nebabin V. G., Kuznetsov I. B. Protection of radar from PRR. Foreign radio electronics, 1991, 4, pp. 67-81.

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Claims (1)

A method for protecting short-wave radio transmitting stations from direction finding, using radio transmitting stations (RPS), spaced apart relative to each other in space and connected to a local communication network containing one or more control controllers, characterized in that they carry out coordinated quasi-coherent emission of signals at the same carrier frequency by several simultaneously radio transmitting stations controlled over a local area network (LAN) using a controller configured to synchronize the operation of the RPS over the LAN and maintain equality of their carrier frequencies, periodically check the readiness of the RPS for transmission and, in the absence of such readiness, exclude it from the addressing cycle transmitted frames, while the controller randomly addresses the transmitted frames of useful information to each of the RPSs, which, upon receiving frames of useful information, simultaneously modulate the carrier, and during the absence of transmission of useful information, the RPSs continue to transmit an unmodulated signal at the carrier frequency, thereby creating the totality of the changing nonlinear structure of the wave front near the direction-finding device.

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