RU2455659C2 - Method of detecting double-loop parametric scatterers - Google Patents

Method of detecting double-loop parametric scatterers Download PDF

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RU2455659C2
RU2455659C2 RU2010136607/07A RU2010136607A RU2455659C2 RU 2455659 C2 RU2455659 C2 RU 2455659C2 RU 2010136607/07 A RU2010136607/07 A RU 2010136607/07A RU 2010136607 A RU2010136607 A RU 2010136607A RU 2455659 C2 RU2455659 C2 RU 2455659C2
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frequency
radio
pulse
signal
pulses
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RU2010136607A (en
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Николай Юрьевич Бабанов (RU)
Николай Юрьевич Бабанов
Александр Сергеевич Корсаков (RU)
Александр Сергеевич Корсаков
Сергей Викторович Ларцов (RU)
Сергей Викторович Ларцов
Иван Сергеевич Ларцов (RU)
Иван Сергеевич Ларцов
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Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Нижегородский государственный технический университет им. Р.Е. Алексеева" (НГТУ)
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Abstract

FIELD: physics.
SUBSTANCE: when detecting double-loop parametric scatterers with parametric excitation frequencies f1 and f2 in order to facilitate application of coherent integration in a receiver, a probing signal is emitted, said signal consisting of a sequence of radio pulses of a pumping signal at frequency f=f2+f1 and a binary sequence of radio pulses of a synchronisation signal at frequency f2, which is encoded according to a defined law, and a binary sequence of radio pulses at frequency f1, which is encoded according to the same law, is used, wherein opposite symbols of the binary sequence correspond to pulses having opposite current phases. Under the effect of these radio-frequency pulses, combinatorial nonlinear noise at frequency of the received signal f1 may appear on the noise nonlinear scatterers. In order to compensate for this noise, a compensating radio pulse is emitted after the synchronising radio pulse at the same frequency and with duration equal to the overlap time of the synchronising radio pulse and the pumping radio pulse.
EFFECT: compensation for nonlinear combinatorial noise.
3 dwg

Description

The invention relates to methods for detecting parametric scatterers.
Known for the [Radio complex search markers, patent RU 2108596 C1] a method for detecting parametric scatterers. The method allows to solve the problem of detecting objects, in particular, people marked with passive non-linear marker responders, which are used parametric scatterers of three types, including dual-circuit parametric scatterers. The method consists in the fact that a double-circuit parametric scatterer with parametric generation frequencies f 1 and f 2 is previously placed on the search object. The region of space in which the search object can be located is irradiated with a probing signal at a frequency f = f 1 + f 2 , a signal scattered by the marker at one of the frequencies of parametric generation f 1 or f 2 is received. If the detection threshold is exceeded, a decision is made about the presence of a search object in the detection zone.
This method has a significant drawback, namely a lack of efficiency, because either it is not possible to use a pulsed probe signal, or coherent reception of the scattered signal is not provided. This is due to the fact that upon excitation of each radio pulse scattered by the signal marker at the frequency of parametric generation, two equally probable phase values differing by π are possible [P. Gorbachev. Signal conditioning by a system of passive subharmonic diffusers. // Radio engineering and electronics, 1995, t 40, N11, p. 1606-1610.]. As a result, the signal scattered at the frequency of parametric generation is not coherent, even with a coherent probe signal.
Also known is a method for detecting bypass parametric scatterers according to [Non-linear passive marker - parametric scatterer, patent RU 2336538 C2]. The method consists in the fact that a double-circuit parametric diffuser with parametric generation frequencies f 1 and f 2 is previously placed on the search object, namely on a life jacket. The region of space in which the search object can be located is irradiated with a probing signal at a frequency f = f 1 + f 2 , a signal scattered by the marker is received at one of the frequencies of the parametric generation of the contours of a dual-circuit parametric scatterer f 1 or f 2 . If the detection threshold is exceeded, a decision is made about the presence of a search object in the detection zone.
The method does not allow the use of coherent signal accumulation in the receiver, since the phase of the generated signal at the frequency of parametric generation is random.
These disadvantages are overcome in the method for detecting single-circuit or dual-circuit parametric scatterers, known from [Lartsov SV. A probe signal for detecting parametric diffusers. // Radio Engineering, 2000, N5, pp. 8-12]. The method allows to solve the problem of detecting objects marked with passive nonlinear responder markers, which are used as dual-circuit parametric scatterers.
This method was chosen as a prototype and consists in the fact that a double-circuit parametric scatterer with parametric generation frequencies f 1 and f 2 is preliminarily placed on the search object, the region of space in which the search object can be located is irradiated by a probing signal, which forms as a result of parametric generation on the parametric diffuser a sequence of packets of narrowband coherent radio pulses of a scattered signal, with each packet corresponding to a code word, and each radio pulse a packet and corresponds to the symbol of the selected coding law, which is a binary sequence, the elements of which correspond, differing by π, to the values of the phase of high-frequency filling of radio pulses, for this the probing signal includes a sequence of packs of narrow-band coherent rectangular radio pulses of a pump signal with a frequency of high-frequency filling f = f 1 + f 2 and pulse duration τ, in addition, the probe signal includes a sequence of narrow-band coherent synchronizing radio pulses with a high-frequency filling frequency f 1 and a radio pulse duration of τ 1 , while τ 1 is significantly less than τ, the high-frequency filling phase of the synchronizing radio pulse corresponds to the current ordinal symbol of the selected manipulation law, and the leading edge of the synchronizing pulse coincides with the leading edge of the pump pulse or is ahead of it by time not exceeding τ 1 , and a sequence of narrow-band coherent radio pulses of a scattered signal with a high-frequency filling frequency equal to at the frequency of parametric generation of the parametric scatterer f 2 , in this case, coherent accumulation is performed according to an algorithm that provides the maximum level of coherent accumulation corresponding to the selected manipulation law, when the detection threshold is exceeded, a decision is made about the presence of a search object in the detection zone
The prototype method allows coherent signal accumulation in the receiving device, however, when detecting double-circuit parametric scatterers, combinational interference may occur due to the simultaneous interaction of the radio pulses of the probe signal and synchronizing radio pulses with interfering nonlinear scatterers, which can be equipment with electronic components. Due to nonlinear scattering, such objects can cause Raman noise at frequencies of Raman nonlinear products. One of these frequencies is the frequency f 2 = ff 1 , which is equal to the frequency of the received signal. The specified coherent interference will have a duration equal to the time of overlapping of the radio pulses of the probe signal and the synchronizing radio pulses τ 2 .
The disadvantage of the prototype is eliminated in the proposed method for the detection of dual-circuit parametric scatterers, which consists in the fact that a double-circuit parametric diffuser with parametric generation frequencies f 1 and f 2 is preliminarily placed on the search object, the region of the space in which the search object can be located is irradiated with a probe signal as a result of parametric generation on a parametric scatterer, a sequence of packets of narrow-band coherent radio pulses scattering each packet corresponds to a codeword, and each radio pulse of the packet corresponds to a symbol of the selected coding law, which is a binary sequence, the elements of which correspond, differing by π, to the phase values of the high-frequency filling of the radio pulses, for this the probing signal includes a sequence of packets of narrow-band coherent rectangular radio pulses of the pump signal with a high-frequency filling frequency f = f 1 + f 2 and pulse duration τ, in addition, the probe the signal includes a sequence of narrow-band coherent synchronizing radio pulses with a high-frequency filling frequency f 1 and a radio pulse duration of τ 1 , while τ 1 is significantly less than τ, the high-frequency phase of the synchronizing radio pulse filling corresponds to the current ordinal symbol of the selected manipulation law, and the leading edge of the synchronizing pulse coincides with the leading edge pump pulse or ahead of it by a time not exceeding τ 1 , and a sequence of narrow-band of coherent radio pulses of a scattered signal with a high-frequency filling frequency equal to the frequency of parametric generation of a parametric scatterer f 2 , while coherent accumulation is performed according to an algorithm that provides the maximum level of coherent accumulation corresponding to the chosen law of manipulation, when the detection threshold is exceeded, a decision is made whether there is a search object in the detection zone wherein, after the synchronizing radio pulse, a compensating radio pulse having such the same as for the synchronizing radio pulse, the amplitude and frequency of the high-frequency filling and the duration τ 2 equal to the overlap time of the synchronizing radio pulse and the pumping pulse, while the high-frequency filling phase of the compensating radio pulse is π different from the high-frequency filling phase of the synchronizing radio pulse.
The essence of the invention lies in the fact that non-linear Raman interference arising on non-linear scatterers of various nature is compensated, for which, after a synchronizing radio pulse, a compensating radio pulse with the same amplitude, high-frequency filling frequency, duration equal to the duration of the specified non-linear noise, and phase different on π. As a result, two interfering radio pulses with identical amplitudes, high-frequency filling frequency, duration, and phases differing by π will be present at the receiver input. Such signals will be mutually compensated in an optimal filter configured to receive one radio pulse, but with a duration longer than the exposure time of both jamming radio pulses.
The proposed detection method can be implemented in a search system, the block diagram of which is shown in Fig. 1, where 1, 2 are sinusoidal signal generators, 3 are high-frequency keys, 4 is a phase-pulse modulator, 5 is a clock pulse generator, 6 is a shaper 7, 8 - amplifiers of radio pulses, 9, 10 - radiating antennas, 11 - parametric scatterer, 12 - receiving antenna, 13 - high-frequency amplifier, 14 - analog-to-digital converter, 15 - signal processor, 16 - indicator.
The output of the sinusoidal signal generator 1 is connected to the signal input 1 of the high-frequency key 3. The output of the sinusoidal signal generator 2 is connected to the signal input 1 of the phase-pulse modulator 4. The output of the clock pulse generator 5 is connected to the input of the shaper 6. The output 1 of the shaper 6 is connected to the control input 2 high-frequency key 3. The output 2 of the shaper 6 is connected to the control input 2 of the phase-pulse modulator 4. The output 3 of the shaper 6 is connected to the clock input 2 of the signal processor 15. The output is high the frequency key 3 is connected to the input of the amplifier of the radio pulses 7. The output of the phase-pulse modulator 4 is connected to the input of the amplifier of the radio pulses 8. The outputs of the amplifiers of the radio pulses 7, 8 are connected to the inputs of the emitting antennas 9, 10, respectively. Antennas 9, 10, 12 are directed in the direction of the parametric diffuser 11. The output of the receiving antenna 12 is connected to the input of the high-frequency amplifier 13. The output of the high-frequency amplifier 13 is connected to the input of the analog-to-digital converter 14. The output of the analog-to-digital converter 14 is connected to the input of the signal processor 15. The output of the signal processor 15 is connected to the input of the indicator 16.
The system operates as follows.
A double-circuit parametric scatterer with parametric generation frequencies f 1 and f 2 is previously placed on the search object.
The generator 1 of the sinusoidal signal generates at its output a continuous sinusoidal signal at the frequency of the probing signal f, which is fed to the signal input 1 of the high-frequency switch 3.
The generator 2 of the sinusoidal signal generates at its output a continuous sinusoidal signal at a frequency f 1 , which is fed to the signal input 1 of the phase-pulse modulator 4.
The clock generator 5 generates at its output a reference pulse sequence of short video pulses, the waveform of which is shown in figure 2 curve 1.
The reference pulse sequence from the output of the clock generator 5 is fed to the input of the shaper 6.
At the output 1 of the shaper 6, the sequence of envelopes of the radio pulses of the pump signal shown in Fig. 2 is shown and fed to input 2 of the high-frequency key 3. All video pulses have the same polarity, the repetition period is T. The curve 2 shown in Fig. 2, the sequence of video pulses corresponds to one packet of 3 video pulses.
At the output 2 of the shaper 6, a sequence of envelopes of synchronizing and compensating radio pulses with a repetition period T, shown in Fig. 2, curve 3 is formed and fed to input 2 of a phase-pulse modulator 4, and the sequence of envelopes of synchronizing and compensating radio pulses is formed synchronous to the reference pulse sequence and is encoding sequence. In Fig.2, curve 3 presents the generated packet of video pulses corresponding to the code word of a particular coding law. The binary Barker sequence of 3 characters “1”, “1”, “0” is selected as the code word of a certain coding law. Binary symbols correspond to different polarity of the first video pulses. The second video pulse always has a polarity opposite to the first. The duration of the second video pulse is shorter than the duration of the first one and corresponds to the overlap time of the first synchronizing video pulse and the video pulse of the envelope of the radio pulse of the pump signal.
At the output 3 of the shaper 6, a short short video pulse is formed and arrives at the synchronizing input 2 of the signal processor 15, which coincides with the leading edge of the video pulse of the pump envelope.
At the output of the high-frequency key 3, a sequence of radio pulses of the pump signal with a high-frequency filling frequency f is shown, curve 4 shown in FIG. 2, which is amplified by the radio pulse amplifier 7 and emitted by the antenna 9. All radio pulses have the same initial phase. In figure 2, curve 4 presents one pack of radio pulses.
At the output of the phase-pulse modulator 4, a sequence of synchronizing and compensating radio pulses is formed with a high-frequency filling frequency f 1 shown in FIG. 2, curve 5, which is amplified by amplifiers of the radio pulses 8 and radiated by the antenna 10. The sequence of radio pulses shown in figure 2, curve 5, corresponds to one pack of radio pulses, which, in turn, corresponds to the Barker binary sequence of 3 characters “1”, “1”, “0”. Different symbols correspond to phases of high-frequency filling of radio pulses that differ by π.
A two-parameter scatterer 11 forms a sequence of narrow-band coherent radio pulses of a scattered signal with a high-frequency filling frequency f 2 = ff 1 , each radio pulse of which corresponds to a symbol of the selected coding law, which is a binary sequence whose symbols correspond to π values of the phase of high-frequency filling of radio pulses represented by 2, curve 6. A certain coding law is a binary Barker sequence of 3- x characters "1", "1", "0".
Figure 2 curve 7 presents the sequence generated from the interference nonlinear scatterers at a frequency of high-frequency filling f 2 . The sequence consists of paired radio pulses with equal amplitude and duration, but with opposite phases of high-frequency filling. The total duration of the interference sequence is less than τ.
The sequence of narrow-band coherent radio pulses of the scattered signal from the dual-circuit parametric scatterer 11 is received by the receiving antenna 12, passes through a high-frequency amplifier 13 and is fed to the input of an analog-to-digital converter 14.
After digitization in the analog-to-digital converter 14, the sequence of narrow-band coherent radio pulses of the scattered signal is processed in the signal processor 15, while the coherent accumulation is performed according to an algorithm that provides the maximum level of coherent accumulation of the received signal corresponding to the selected manipulation law, when the detection threshold is exceeded, a decision is made whether the detection area of the search object, which is displayed on the indicator 16.
The signal processor 15 operates in accordance with the algorithm presented in Fig. 3, where 17 is a splitter, 18, 20 are inverters, 19 is a delay line for a time equal to the pulse repetition period T, 21 is a delay line for a time equal to two repetition periods pulses 2T, 22 - adder, 23 - optimal filter for a radio pulse, with duration τ, 24 - threshold device, 25 - range determination unit.
The signal processor 15 operates as follows. Using a splitter 17, inverters 18 and 20, delay lines 19, 21 and the adder 22, the optimal coherent addition of the input signal in the form of a Barker sequence of 3 elements is performed. Next, the signal passes through an optimal filter 23 tuned to a radio pulse with a duration of τ, where it is detected and from the output 2 of the optimal filter 23 is fed to the signal input 1 of the threshold device 24. The detection threshold value is input to the input 2 of the threshold device 24. When the signal exceeds the detection threshold of the detection threshold, a decision is made about the presence of a search object in the detection zone and the detection signal from the output of the threshold device 24 is sent to the indicator. At the same time, the moment of the maximum signal of the detection result from the output 1 of the optimal filter 23 is compared with the moment of arrival of the reference short video pulse from the output 3 of the driver 6. The distance to the search object, which is indicated on the indicator, is determined by the time difference between the maximum of the signal of the result of the detection and the reference short video pulse.
Paired radio pulses of the sequence generated from the interference of nonlinear scatterers at a frequency of high-frequency filling f 2 are mutually compensated in the optimal filter 23.
As generators of the sinusoidal signal 1, 2 can be used standard generators G4-164. Pulse-phase modulator 4 can be implemented according to [S.A.Drobov, S.I. Bychkov Radio transmitting devices // Sov. Radio, M. 1968, pp. 299-335]. Amplitude modulator 3 can be implemented according to [S.A.Drobov, S.I. Bychkov Radio transmitting devices // Sov. Radio, M. 1968, pp. 240-277]. As the generator of clock pulses 5 can be used a standard generator G5-28, shaper 6 can be implemented according to [V.G. Gusev, Yu.M. Gusev Electronics // M. Higher School, 1991, 2nd edition revised and supplemented , pp. 489-585]. As amplifiers of radio pulses 7, 8, amplifiers from a standard generator G4-128 can be used. As the radiating antennas 9, 10 and the receiving antenna 12 can be used antennas P6-33. A dual-circuit or single-circuit parametric diffuser can be made on the basis of the patent [Non-linear passive marker - parametric diffuser, patent RU 2336538 C2].
As a high-frequency amplifier 13, a standard low-noise amplifier MAX 2640 can be used. As an analog-to-digital converter 14, an ZET 230 ADC can be used. As a signal processor 15, a signal processor TMS 320C 2000 can be used. As an indicator 16, a computer can be used like Pentium 4.
Thus, the proposed technical solution for the detection of dual-circuit parametric scatterers allows for the mutual compensation of nonlinear interference arising from interfering nonlinear scatterers.

Claims (1)

  1. A method for detecting double-circuit parametric scatterers, which consists in the fact that a double-circuit parametric diffuser with parametric generation frequencies f 1 and f 2 is preliminarily placed on the search object, the region of space in which the search object can be located is irradiated with a probe signal, which forms as a result of parametric generation on a parametric scatterer, a sequence of packets of narrow-band coherent radio pulses of a scattered signal, each packet corresponding to the code word, and each radio pulse of the packet corresponds to a symbol of the selected coding law, which is a binary sequence, the elements of which correspond to different π values of the phase of the high-frequency filling of the radio pulses, for this the probing signal includes a sequence of packets of narrow-band coherent rectangular radio pulses of a pump signal with a high-frequency filling frequency f = f 1 + f 2 and pulse duration τ, in addition, the probing signal includes a sequence of narrow of coherent synchronizing radio pulses with a high-frequency filling frequency f 1 and a radio pulse duration of τ 1 , with τ 1 being significantly shorter than τ, the high-frequency filling phase of the synchronizing radio pulse corresponds to the current ordinal symbol of the selected manipulation law, and the leading edge of the synchronizing pulse coincides with or is ahead of the leading edge of the pump pulse it at the time, not exceeding τ 1, and receives a sequence of narrow-band coherent radio pulses scattered signal pilots at the high-frequency equal to the frequency of the parametric generation parametric diffuser f 2, wherein the produced coherent accumulation by the algorithm provides the maximum level of the coherent accumulation corresponding to the selected law manipulation when exceeding the detection threshold decision on the presence in the zone of detection of the search object, characterized in that after the synchronizing radio pulse, a compensating radio pulse is emitted having the same as that of the synchronizing radio Pulse amplitude and frequency of the high-frequency, and duration τ 2 equal overlap time synchronizing radio impulse radio pulse and the pump, wherein the phase compensating the high-frequency radio pulse differs by π from the phase of the high-frequency synchronizing radio pulse.
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US4757315A (en) * 1986-02-20 1988-07-12 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method and apparatus for measuring distance
RU94036233A (en) * 1994-09-28 1996-07-20 С.А. Бахарев Device for detecting and direction finding of low-frequency hydroacoustic radiations
RU2145424C1 (en) * 1999-06-21 2000-02-10 Воронежское конструкторское бюро антенно-фидерных устройств Method of detection of object ( versions )
EP1640745A3 (en) * 2004-09-24 2007-10-03 Meta System S.p.A. Obstacle detection method and system, particularly for systems for assisting the parking of vehicles
RU2336538C2 (en) * 2006-06-28 2008-10-20 Сергей Викторович Ларцов Non-linear passive marker-parameter diffuser
WO2010034933A1 (en) * 2008-09-23 2010-04-01 Universite Paris 13 System and method for detecting at least one object having a marker

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4757315A (en) * 1986-02-20 1988-07-12 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method and apparatus for measuring distance
RU94036233A (en) * 1994-09-28 1996-07-20 С.А. Бахарев Device for detecting and direction finding of low-frequency hydroacoustic radiations
RU2145424C1 (en) * 1999-06-21 2000-02-10 Воронежское конструкторское бюро антенно-фидерных устройств Method of detection of object ( versions )
EP1640745A3 (en) * 2004-09-24 2007-10-03 Meta System S.p.A. Obstacle detection method and system, particularly for systems for assisting the parking of vehicles
RU2336538C2 (en) * 2006-06-28 2008-10-20 Сергей Викторович Ларцов Non-linear passive marker-parameter diffuser
WO2010034933A1 (en) * 2008-09-23 2010-04-01 Universite Paris 13 System and method for detecting at least one object having a marker

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ЛАРЦОВ С.И. Зондирующий сигнал для обнаружения параметрических рассеивателей. - Радиотехника, 2000, №5, с.8-12. *

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