RU2608338C1 - Signals processing device in ground and space forward-scattering radar system - Google Patents

Abstract

FIELD: radars.

SUBSTANCE: invention relates to radars and can be used for processing signals when detecting stealth targets in ground and space forward-scattering radar systems (RS). Simplified design of antenna feeder units and reduced weight and dimensions is achieved due to that different antennae are not required for reception of direct and scattered signals, neither multi-frequency transceiving modules, nor high-sensitive receivers. Higher stealthiness of the proposed forward-scattering RS is achieved by using as the sounding continuous signal the one with digital modulation, the width of spectrum of which considerably exceeds the range of possible Doppler frequency shifts when reflecting from detected targets. To achieve the specified technical result in a device containing a transmitting position of a transmitter and an antenna, a receiving position, which includes a receiving antenna, N receivers, N units for measuring the Doppler frequency with connected outputs to N inputs of the unit for determining bearing, the output of which is the output of the device, there is at the receiving position between each receiver and the unit for measuring the Doppler frequency a signals processing device including series-connected: a demodulator, a coherent accumulator, a direct signal generator and a subtractor, as well as a delay line, the input of which is connected to the output of the receiver, and the output – to the second input of the subtractor, herewith the transmitting position is located in space, emits a continuous signal with digital modulation and generates one “wide” beam covering the entire zone of scanning, and on the ground receiving position there are N partial beams.

EFFECT: technical result of the proposed invention is reduction of cost of a ground and space forward-scattering RS as a whole not requiring launching new satellites while simplifying the design of antenna feeder units, reducing weight and overall dimensions and the increase of the forward-scattering RS stealthiness.

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Description

The invention relates to radar and can be used to process signals in solving the problem of detecting inconspicuous targets in ground-space translucent radar systems (radar).

Currently, the share of unmanned aerial vehicles (UAVs) is significantly increasing in the aviation sector. Modern subtle BILA can be made using stealth technology, have a supersonic maximum speed and a practical ceiling of about 20 km. Unlike many aircraft, UAVs, as a rule, have significantly smaller sizes and, consequently, a smaller effective scattering area, which makes them difficult to detect with monostatic radars. The use of radar "in the light" can reduce the required energy potential of the radar needed to detect such targets. In the case of the use of ground-space clearance radars, the UAV detection height restriction inherent to the clearance radar with transmitting and receiving ground and air-based positions, respectively, is removed [1].

It is relevant to use existing spacecraft (SC) for various purposes (GPS / GLONASS, telecommunication, etc.) as transmitting posts of the translucent multi-position ground-space radar. Such a configuration can significantly reduce the material costs associated with the launch of new satellites, and ensure the secrecy of the operation of such a system, because only the receiving part of the luminal radar is designed.

When creating a transparent radar, it is necessary to ensure the selection of a weak signal scattered by the target and a strong direct signal of the transmitting position. The specific method of signal selection depends on many factors, among which the type of the probing signal, the configuration of the antenna system of the receiving position and the sensitivity of the receiver should be noted.

Known ground-based space radar [2, 3], containing a space-based or air-based transmitter, the carrier of which is a satellite or flight-lifting means, and spaced radar receiving devices located on cell towers. To select the scattered signal, the spatial selection method is applied by using additional narrowly targeted antennas oriented to a given area. The disadvantages of such an illuminated radar include the need to use additional antennas and higher requirements for the energy potential necessary to detect subtle targets, for example targets made using stealth technology.

A similar version of a bistatic ground-space radar with a group of ground-based receivers was considered in [4]. The same authors in [5] proposed a variant of a ground-space radar that implements the principle of radar "in the light". To extract the scattered signal, highly sensitive receivers are used in combination with the method of temporary signal selection.

Another translucent ground-space radar complex is known [6], where space-based natural or artificial noise sources are used as the transmitting position, and the receiving station is ground-based. Provides spatial and temporal selection of direct and scattered signals.

The disadvantages of analogues [4, 5, 6] include the need to use highly sensitive receivers and additional antennas for receiving a scattered signal.

The closest analogue of the proposed device (prototype) is the ground-space translucent radar [7], shown in FIG. 1, consisting of a receiver located on a space carrier and a ground transmitting position. The transmitting position comprises a multi-frequency transmitter 1 and a transmitting antenna 2 connected in series, forming N partial rays and emitting a continuous quasi-harmonic probe signal, which is the sum of signals having different carrier frequencies.

The composition of the receiving position includes a broadband receiving antenna 3, receiving channels, the number of which is equal to the number of partial channels of the transmitting position, as well as a bearing detecting unit 8. Each channel of the receiving position, multichannel in frequency, consists of a series-connected high-pass bandpass filter 4, receiver 5, device 6 for notching the direct signal of the transmitter and passive interference and the unit 7 for measuring Doppler frequency. Moreover, the outputs of the blocks 7 measuring the Doppler frequency of each channel are connected to the inputs of the block 8 of the determination of the bearing. At the receiving position, one “wide” beam is formed, which should overlap the area of space irradiated by all the rays of the transmitter.

At the receiving position, frequency selection of the direct and scattered signals is provided. Thus, in the prototype device [7], the disadvantages of the analogues [4, 5, 6] are overcome.

In systems [1, 7] using a continuous quasi-harmonic probe signal, the spectra of the direct and scattered signals are spaced along the frequency axis. Due to this, the use of a notch filter allows the direct signal to be suppressed to its own noise level, as shown in FIG. 2, where 1 are the spectral components of the direct signal, 2 are the spectral components of the signal scattered by the target, 3 is the amplitude-frequency characteristic of the notch filter, F ₀ is the center frequency of the direct signal, F _dC is the target Doppler frequency.

Existing navigation and telecommunication satellites emit a continuous signal with digital phase modulation, digital amplitude-phase modulation, digital frequency modulation, the width of the spectrum of which significantly exceeds the Doppler frequency shift of the signal scattered by the air target, and therefore the use of a notch filter does not allow suppressing the direct signal, without suppressing the scattered signal, as The spectral components of the direct and scattered signals will almost completely overlap. In FIG. Figure 3 illustrates this situation, where 1 is the spectral components of the direct signal, 2 are the spectral components of the signal scattered by the target.

The first disadvantage of the prototype is the need to launch special satellites, which increases the cost of the system as a whole. The second disadvantage is that the method of frequency selection of signals used in the prototype is designed only for a continuous quasi-harmonic probe signal, and the signals of existing spacecraft, being continuous, have digital modulation and are not quasi-harmonic. In addition, in the prototype, it is necessary to use a multi-frequency transmitter and multi-frequency antennas, which complicates the design of the antenna-feeder nodes and increases the overall dimensions.

The technical result of the invention is to reduce the cost of the ground-space luminaire radar as a whole, which does not require the launch of new satellites, while simplifying the design of antenna-feeder nodes, reducing the overall dimensions and increasing the secrecy of the luminal radar.

Simplification of the design of antenna-feeder nodes and reduction of overall dimensions is achieved by the fact that various antennas are not required for receiving direct and scattered signals, multi-frequency transceiver modules, and highly sensitive receivers.

Increasing the secrecy of the proposed translucent radar is achieved by using as a probing continuous signal with digital modulation, the width of the spectrum of which significantly exceeds the range of possible Doppler frequency shifts when reflected from detected targets.

To achieve the specified technical result in a device containing a transmitting position as part of a transmitter and an antenna, a receiving position, which includes a receiving antenna, N receivers, N Doppler frequency measuring units with connected outputs to N inputs of the bearing detection unit, the output of which is the output of the device , introduced at the receiving position between each receiver and the unit for measuring the Doppler frequency signal processing device containing a serially connected demodulator, coherent opitel, direct signal generator and subtraction unit, as well as a delay line, the input of which is connected to the output of the receiver, and the output - to the second input of the subtraction unit, and the transmitting position is in space, emits a continuous signal with digital modulation and forms one "wide" beam , covering the entire field of view, and at the ground receiving position formed N partial rays.

In FIG. 4 shows a functional diagram of the inventive device, where the following notation:

1 - transmitter;

2 - antenna transmitting position;

3 - antenna receiving position;

5 - receiver;

7 - unit for measuring Doppler frequency;

8 - bearing detection unit;

9 - signal processing device;

10 - demodulator;

11 - coherent drive;

12 - direct signal generator;

13 - block subtraction;

14 - delay line.

The proposed device consists of a ground receiving position, relative to which the primary parameters are measured, and a transmitting position, which is used as an existing spacecraft operating in the normal mode. The transmitting position contains the transmitter 1 and the antenna of the transmitting position 2. The receiving ground position consists of antenna 3, receiving channels, the number of which is equal to the number of partial rays of the receiving position, and bearing detecting unit 8. Each receiving channel consists of a receiver 5 and a signal processing device connected in series 9. The signal processing device 9 consists of a demodulator 10, a coherent drive 11, a direct signal generator 12, a subtraction unit 13, while the output of the receiver 5 is also connected to the input of the delay line 14, the output d which is connected to the second input 13 of the subtractor. The output of the unit 7 for measuring the Doppler frequency of each channel of the receiving position is connected to the corresponding input of the unit 8 for determining the bearing.

The inventive device operates as follows.

As the transmitting position, consisting of the transmitter 1 and antenna 2 of the transmitting position, the existing spacecraft is used, on which one "wide" beam of the radiation pattern is formed. At the ground receiving position, N partial beams of the radiation pattern at one frequency are formed. The direct signal and the signal scattered by the target are received simultaneously by several partial beams in space and the total oscillation arrives at the input of the receiving channels. The total signal corresponds to one target.

From the receiver 5, the total signal is supplied to the demodulator 10 of the signal processing unit 9. Since the power of the scattered signal is several orders of magnitude lower than the power of the direct signal, the influence of the scattered signal during demodulation of the direct signal can be neglected. The obtained estimate of the sequence of information symbols allows coherent accumulation of the direct signal in the coherent storage device 11. With coherent accumulation of the direct signal and its compensation, it is necessary to provide Doppler frequency resolution between the direct signal and the scattered signal to exclude partial suppression of the scattered signal. For this, the direct signal accumulation interval is chosen so that its high correlation region is less than the required Doppler frequency resolution of the scattered signal. After coherent accumulation, the amplitude and initial phase are estimated. The received information about the direct signal is sufficient to synthesize its local copy in the direct signal generator 12, which is then subtracted from the delayed total signal in the subtraction unit 13. The delay line 14 provides a delay of the total signal by at least the size of the coherent accumulation interval of the direct signal. In block 7, the Doppler frequency measurement of each channel is determined by the Doppler frequency of the signal scattered by the target. The determination of the angular coordinates of the target in block 8 of the bearing is determined by comparing the amplitudes of the signals from the same target in different receiving channels.

Thus, the introduction of a known device containing a transmitting position in the composition of the transmitter and antenna, a receiving position, which includes a receiving antenna, N receivers, N Doppler frequency measuring units with connected outputs to N inputs of the bearing detection unit, the output of which is the output of the device connected in series to a demodulator, coherent storage device, direct signal generator, subtraction unit, and also a delay line at the receiving position between each receiver and the Doppler measurement unit frequency, the input of the delay line is connected to the output of the receiver, and the output is connected to the second input of the subtraction unit, and the transmitting position located on the existing spacecraft emits a continuous signal with digital modulation and forms one "wide" beam that covers the entire field of view, and the receiving the ground-based position forms N partial beams, which ensures the creation of a signal processing device in the ground-space luminal radar that does not require the launch of new satellites, while simplifying the design of antenna-feeder zlov, reduced weight and size, and an increase in luminal stealth radar.

Information sources

1. RF patent №2324951 "Terrestrial-space radar complex", publ. 05/20/2008, IPC G01S 13/06, Н04В 7/24, authors A.B. Blyakhman, A.V. Samarin.

2. Ksendzuk, A.V. Non-radiating radar system based on the reception of reflected signals from the GLONASS and GPS navigation systems [Text] / А.V. Ksendzuk, V.F. Fateev, S.A. Popov // Transactions of OJSC "IAC" Vympel ". Digest of articles. M .: Radio engineering, 2009 - No. 4 - S. 60-66.

3. RF patent No. 113022 “Terrestrial-space radar system”, publ. 01/27/2012, IPC G01S 13/06, authors V.F. Fateev, A.V. Xendzuk.

4. RF patent No. 109569 "Device for detecting air targets using signals from satellite radio navigation systems", publ. 10/20/2011, IPC G01S 5/02, G01S 13/56, authors V.V. Kiryushkin, D.A. Cherepanov, A.A. Disenov, S.S. Tkachenko.

5. Kiryushkin, V.V. Evaluation of the possibility of recording airborne signals of satellite navigation systems by modern and promising receivers [Text] / V.V. Kiryushkin, D.A. Cherepanov, N.M. Tikhomirov // Collection of reports of the XVII International Scientific and Technical Conference "Radar, Navigation, Communication" - NPF "SAKVOEE", Voronezh, 2011 - April 12-14 - Volume 3 - P. 2119-2124.

6. RF patent No. 2422849 "Radar complex", publ. 06/27/2011, IPC G01S 13/02, authors A.A. Antipenko, A.F. Dementiev, N.A. Dugin et al.

7. RF patent No. 2402034 "Radar method for determining the angular position of the target and a device for its implementation", publ. 10.20.2010, IPC G01S 3/72, authors A.B. Blyakhman, A.V. Samarin, A.G. Ryndyk, A.V. Myakinkov.

Claims (1)

A signal processing device in the ground-space translucent radar system containing a transmitting position as a part of a transmitter and an antenna, a receiving position, which includes a receiving antenna, N receivers, N Doppler frequency measuring units with connected outputs to N inputs of the bearing detection unit, the output of which is the output of the device, characterized in that the transmitting position is located in space, emits a continuous signal with digital modulation and forms one "wide" beam, covering the entire zones at the survey, and at the ground receiving position, N partial beams are formed, in addition, at the receiving position between each receiver and the Doppler frequency measuring unit, a series-connected demodulator, a coherent drive, a direct signal generator and a subtraction unit are additionally introduced, as well as a delay line, an input which is connected to the output of the receiver, and the output to the second input of the subtraction unit.

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