Radar signal receiving and forwarding interference method based on electro-optic phase modulation

Abstract

The invention provides a radar signal receiving and forwarding interference method based on electro-optic phase modulation. The method comprises the steps that a device is built; carrier waves emitted by a continuous wave laser are split by an optical fiber beam splitter and then are respectively input into a first phase modulator and a second phase modulator; received radar signals are divided into two paths, one path is input into the first phase modulator, and the other path is input into the second phase modulator after phase modulation of the adjustable electrical phase shifter; a modulation signal output by the first phase modulator is input into the high-speed optical switch, a regulation and control signal controls the high-speed optical switch to be switched between on and off, and intermittent sampling modulation is achieved; a modulation signal output by the second phase modulator is input into the adjustable light phase shifter, and the adjustable light phase shifter carries out phase modulation on the modulation signal; output signals of the high-speed optical switch and the adjustable optical phase shifter are input into the balanced photoelectric detector through the 90-degree optical bridge for photoelectric conversion, and radar interference signals are generated. According to the invention, the regularity of electronic interference of traditional intermittent sampling is broken.

Description

Technical Field

[0001] The present invention relates to the fields of electronic jamming and radar technology, and particularly to a radar signal receiving and forwarding jamming method based on electro-optic phase modulation. Background Art

[0002] To balance the operating range and resolution, radars mostly adopt the LFM signal (linear frequency modulation signal of radar) with pulse compression system. The interference effect of traditional non-coherent interference signals on pulse compression radars is greatly reduced. Coherent interference mostly uses digital radio frequency storage to achieve. However, digital radio frequency storage requires a relatively complex hardware architecture, and its instantaneous operating bandwidth is limited by the electronic bottleneck problem. Microwave photonics technology has technical advantages such as large bandwidth, low transmission loss, and anti-electromagnetic interference. Based on microwave photonics methods, the interference system can directly perform analog domain modulation on the intercepted radar signal in the optical domain, avoiding the complex analog-to-digital and digital-to-analog conversion processes, and breaking through the bandwidth limitation of traditional electronic jammers. The intermittent sampling and forwarding interference based on microwave photonics does not need to collect complete radar pulse signals and has the potential to counter radar systems with waveform agility, frequency agility, etc. In addition, due to the range-Doppler coupling effect of the LFM pulse compression system radar, it can form the interference effect of leading false target strings. Currently, some photon-assisted intermittent sampling methods have been proposed. Intermittent sampling can be generated by the bias port of a Mach-Zehnder modulator to generate false target strings. However, the Mach-Zehnder modulator is prone to the phenomenon of working point shift during long-term operation, resulting in system instability, and the false target center generated by the interference signal is the strongest, gradually weakening at equal intervals along both sides, with too strong regularity and being easily identified by the radar system. Summary of the Invention

[0003] Aiming at the defects existing in the prior art, the present invention provides a radar signal receiving and forwarding jamming method based on electro-optic phase modulation.

[0004] To achieve the above technical objectives, the technical solutions adopted by the present invention are as follows: The present invention provides a radar signal receiving and forwarding jamming method based on electro-optic phase modulation, including: Building a radar signal receiving and forwarding jamming device based on electro-optic phase modulation; The carrier wave emitted by the continuous wave laser is split by an optical fiber splitter and then input into the first phase modulator and the second phase modulator respectively; The received radar signal is divided into two paths. One path is input into the first phase modulator, and the other path is input into the second phase modulator after being phase-modulated by an adjustable electrical phase shifter; The modulation signal output by the first phase modulator is input into a high-speed optical switch, and the control signal controls the high-speed optical switch to switch between on and off to achieve intermittent sampling modulation; The modulated signal output by the second phase modulator is input into the tunable optical phase shifter, and the tunable optical phase shifter performs phase modulation on the modulated signal; The output signals of the high-speed optical switch and the tunable optical phase shifter are input into the balanced photodetector through a 90° optical bridge for optoelectronic conversion to generate a radar jamming signal.

[0005] Furthermore, the radar signal receiving and forwarding jamming device based on electro-optic phase modulation includes a continuous-wave laser, a phase modulator, a high-speed optical switch, a tunable optical phase shifter, a 90° optical bridge, a balanced photodetector, an optical fiber splitter, a tunable electrical phase shifter, an antenna, and a signal generating device; The carrier wave generated by the continuous-wave laser is split by the optical fiber splitter and then injected into the input ports of the first phase modulator and the second phase modulator respectively; the radar signal received by the antenna is divided into two paths, one path is input into the RF input port of the first phase modulator, and the other path is input into the RF input port of the second phase modulator after passing through the tunable electrical phase shifter; the optical signal output by the first phase modulator passes through the high-speed optical switch and then is input into the balanced photodetector through the 90° optical bridge; the optical signal output by the second phase modulator passes through the tunable optical phase shifter and then is input into the balanced photodetector through the 90° optical bridge; the balanced photodetector performs optoelectronic conversion on the received optical signal and outputs a radar jamming signal; A signal generating device is connected to the high-speed optical switch for generating a control signal for intermittent sampling.

[0006] Furthermore, the signal generating device includes a vector signal generator, a function signal generator, an analog signal source, and an arbitrary signal generator.

[0007] Furthermore, a DC bias source is connected to both the tunable optical phase shifter and the tunable electrical phase shifter.

[0008] Furthermore, a spectrum analyzer is further included, and the spectrum analyzer is connected to the balanced photodetector for observing the spectral characteristics of the radar jamming signal.

[0009] Furthermore, a power amplification device is further included, and the power amplification device is connected to the balanced photodetector for boosting the power of the radar jamming signal.

[0010] Furthermore, the continuous-wave laser generates a carrier wave with a working wavelength of 1550 nm.

[0011] Furthermore, the control signal is a rectangular pulse train.

[0012] Furthermore, when the phase shift amount of the tunable electrical phase shifter is 90° and the phase shift amount of the tunable optical phase shifter is 0°, the generated false targets are symmetrically distributed and the amplitudes decrease in sequence; When the phase shift amount of the adjustable electrical phase shifter is 90° and the phase shift amount of the adjustable optical phase shifter is 90°, the generated false targets are asymmetrically distributed.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are as follows: A radar signal receiving and forwarding interference method based on electro-optic phase modulation provided by the present invention receives a radar signal through two parallel phase modulators, performs optical modulation and then outputs it. One path of the modulated signal is intermittently sampled by a high-speed optical switch; the phase shift amount of the other path of the modulated signal is adjusted by an adjustable electrical phase shifter. By adjusting the phase shift amount of the signal, the generated false target signal can be affected, and the distribution of the false target signal can be changed, so that the generated radar interference signal is in a symmetric distribution state or an asymmetric distribution state, breaking the regularity of traditional intermittent sampling electronic interference.

[0014] A radar signal receiving and forwarding interference method based on electro-optic phase modulation provided by the present invention has the advantages of large signal processing bandwidth, flexible adjustable interference distribution, and no need for analog-to-digital and digital-to-analog conversion, and has broad application prospects. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0016] Figure 1 Schematic diagram of a radar signal receiving and forwarding interference device based on electro-optic phase modulation provided for an embodiment; Figure 2 Schematic diagram of the time domain and frequency domain of an LFM radar signal provided for an embodiment, where Figure 2 (a) is the time domain diagram of the LFM radar signal, Figure 2 (b) is the frequency domain diagram of the LFM radar signal; Figure 3 Schematic diagram of a sampling pulse output by a vector signal generator provided for an embodiment; Figure 4 Interference effect diagram of a radar interference signal provided for an embodiment, where Figure 4 (a) is the interference effect diagram when the phase shift amount of the adjustable electrical phase shifter 5 is 90° and the phase shift amount of the adjustable optical phase shifter 6 is 0°; Figure 4 (b) is the interference effect diagram when the phase shift amount of the adjustable electrical phase shifter 5 is 90° and the phase shift amount of the adjustable optical phase shifter 6 is 90°.

[0017] Attached figure labels: Continuous wave laser 1, antenna 2, first phase modulator 3, second phase modulator 4, adjustable electrical phase shifter 5, adjustable optical phase shifter 6, first DC bias source 7, second DC bias source 8, high-speed optical switch 9, signal generating device 10, 90° optical bridge 11, balanced photodetector 12. Detailed implementation mode

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0019] In one embodiment, a radar signal receiving and forwarding interference method based on electro-optic phase modulation is provided, including: Construct a radar signal receiving and forwarding interference device based on electro-optic phase modulation; The carrier wave emitted by the continuous wave laser 1 is split by an optical fiber splitter and then input into the first phase modulator 3 and the second phase modulator 4 respectively; The received radar signal is divided into two paths. One path is input into the first phase modulator 3, and the other path is input into the second phase modulator 4 after being phase-modulated by the adjustable electrical phase shifter 5; The modulation signal output by the first phase modulator 3 is input into the high-speed optical switch 9, and the control signal controls the high-speed optical switch 9 to switch between on and off to achieve intermittent sampling modulation; The modulation signal output by the second phase modulator 4 is input into the adjustable optical phase shifter 6, and the adjustable optical phase shifter 6 performs phase modulation on the modulation signal; The output signals of the high-speed optical switch 9 and the adjustable optical phase shifter 6 are input into the balanced photodetector 12 through the 90° optical bridge 11 for photoelectric conversion to generate a radar interference signal.

[0020] When the phase shift amount of the adjustable electrical phase shifter 5 is 90° and the phase shift amount of the adjustable optical phase shifter 6 is 0°, the generated false targets are symmetrically distributed and the amplitudes decrease in turn; When the phase shift amount of the adjustable electrical phase shifter 5 is 90° and the phase shift amount of the adjustable optical phase shifter 6 is 90°, the generated false targets are asymmetrically distributed.

[0021] Referring to Figure 1 , the radar signal receiving and forwarding interference device based on electro-optic phase modulation includes a continuous wave laser 1, a phase modulator, a high-speed optical switch 9, an adjustable optical phase shifter 6, a 90° optical bridge 11, a balanced photodetector 12, an optical fiber splitter, an adjustable electrical phase shifter 5, an antenna 2, and a signal generating device 10; The carrier wave generated by the continuous wave laser 1 is split by an optical fiber splitter and then injected into the input ports of the first phase modulator 3 and the second phase modulator 4 respectively; the radar signal received by the antenna 2 is divided into two paths, one path is input into the RF input port of the first phase modulator 3, and the other path is input into the RF input port of the second phase modulator 4 after passing through the adjustable electrical phase shifter 5; the optical signal output by the first phase modulator 3 passes through the high-speed optical switch 9 and then is input into the balanced photodetector 12 through the 90° optical bridge 11; the optical signal output by the second phase modulator 4 passes through the adjustable optical phase shifter 6 and then is input into the balanced photodetector 12 through the 90° optical bridge 11; the balanced photodetector 12 performs optoelectronic conversion on the received optical signal and outputs a radar interference signal; A signal generating device 10 is connected to the high-speed optical switch 9 for generating a control signal for intermittent sampling.

[0022] DC bias sources are connected to both the adjustable optical phase shifter 6 and the adjustable electrical phase shifter 5. Specifically, in this embodiment, the adjustable optical phase shifter 6 is connected to the second DC bias source 8, and the adjustable electrical phase shifter 5 is connected to the first DC bias source 7; by controlling the phase shift amounts of the adjustable optical phase shifter 6 and the adjustable electrical phase shifter 5 through the DC bias sources, precise adjustment of the phase can be achieved.

[0023] The signal generating device 10 includes a vector signal generator, a function signal generator, an analog signal source, and an arbitrary signal generator.

[0024] In one embodiment, the control signal generated by the signal generating device 10 is a rectangular pulse train.

[0025] In one embodiment, a radar signal receiving and forwarding interference device based on electro-optic phase modulation includes a continuous wave laser 1, a phase modulator, a high-speed optical switch 9, an adjustable optical phase shifter 6, a 90° optical bridge 11, a balanced photodetector 12, an optical fiber splitter, an adjustable electrical phase shifter 5, an antenna 2, and a signal generating device 10; The carrier wave generated by the continuous wave laser 1 is split by an optical fiber splitter and then injected into the input ports of the first phase modulator 3 and the second phase modulator 4 respectively; the radar signal received by the antenna 2 is divided into two paths, one path is input into the RF input port of the first phase modulator 3, and the other path is input into the RF input port of the second phase modulator 4 after passing through the adjustable electrical phase shifter 5; the optical signal output by the first phase modulator 3 passes through the high-speed optical switch 9 and then is input into the balanced photodetector 12 through the 90° optical bridge 11; the optical signal output by the second phase modulator 4 passes through the adjustable optical phase shifter 6 and then is input into the balanced photodetector 12 through the 90° optical bridge 11; the balanced photodetector 12 performs optoelectronic conversion on the received optical signal and outputs a radar interference signal; A signal generating device 10 is connected to the high-speed optical switch 9 for generating a control signal for intermittent sampling; It further includes a spectrum analyzer, which is connected to the balanced photodetector 12 and is used to observe the spectral characteristics of the radar interference signal.

[0026] By connecting a spectrum analyzer or an oscilloscope, observe the time-domain waveform and spectral characteristics of the radar interference signal, and observe the interference effect of the radar interference signal on the radar through matched filtering processing.

[0027] In one embodiment, the radar signal receiving and forwarding interference device based on electro-optic phase modulation further includes a power amplification device, which is connected to the balanced photodetector 12 and is used to increase the power of the radar interference signal.

[0028] By accessing the power amplification device, amplify the generated radar interference signal, so that the radar interference signal has a greater power, can cover the real target echo signal, and enables the radar interference signal to better achieve the interference effect.

[0029] In one embodiment, the continuous wave laser 1 generates a carrier wave with a working wavelength of 1550 nm.

[0030] In one embodiment, the carrier wave with a working wavelength of 1550 nm generated by the continuous wave laser 1 is split by an optical fiber splitter and then input into the first phase modulator 3 and the second phase modulator 4 respectively; Refer to Figure 2 , the carrier frequency of the LFM radar signal received by the antenna 2 is 10 GHz, the bandwidth is 100 MHz, and the pulse width is 10 μs. The LFM radar signal is divided into two paths. One path is input into the first phase modulator 3, and the other path is phase-modulated by the adjustable electrical phase shifter 5 and then input into the second phase modulator 4. The first DC bias source 7 controls the phase shift amount of the adjustable electrical phase shifter 5 to be 90°; The modulation signal output by the first phase modulator 3 is input into the vector signal generator. Refer to Figure 3 , the vector signal generator generates a rectangular pulse train, the pulse duty cycle is 50%, the frequency is 1 MHz, and the low level is the turn-off voltage of the high-speed optical switch 9 V OFF , the high level is the turn-on voltage of the high-speed optical switch 9 V ON , the rectangular pulse train controls the high-speed optical switch 9 to switch between on and off, realizing the intermittent sampling of the modulation signal output by the first phase modulator 3; The modulation signal output by the second phase modulator 4 is input into the adjustable optical phase shifter 6. The adjustable optical phase shifter 6 performs phase modulation on the modulation signal. The second DC bias source 8 controls the phase shift amount of the adjustable optical phase shifter 6 to be 0°; The output signals of the high-speed optical switch 9 and the adjustable optical phase shifter 6 are input into the balanced photodetector 12 with a responsivity of 0.7 A / W through the 90° optical bridge 11 to complete photoelectric conversion and generate a radar interference signal.

[0031] The radar interference signal output by the balanced optoelectronic detector 12 is subjected to matched filtering, that is, the radar interference signal is cross-correlated with the input LFM radar signal, so as to observe the interference effect of the generated radar interference signal.

[0032] In one embodiment, in order to verify the influence of the phase shift amounts of the tunable electrical phase shifter 5 and the tunable optical phase shifter 6 on the false target distribution, while keeping all other parameters unchanged, the first DC bias source 7 is adjusted so that the phase shift amount of the tunable electrical phase shifter 5 is and the second DC bias source 8 is adjusted so that the phase shift amount of the tunable optical phase shifter 6 is The above process is repeated to observe the interference effect of the output radar interference signal.

[0033] Referring to Figure 4 Figure 4 shows the interference effect of the radar interference signal. Figure 4 (a) shows the interference effect when the phase shift amount of the tunable electrical phase shifter 5 is 90° and the phase shift amount of the tunable optical phase shifter 6 is 0°; Figure 4 (b) shows the interference effect when the phase shift amount of the tunable electrical phase shifter 5 is 90° and the phase shift amount of the tunable optical phase shifter 6 is 90°. It can be seen from Figure 4 that as the phase shift amounts of the tunable electrical phase shifter 5 and the tunable optical phase shifter 6 change, the number of false targets changes continuously, and the string of false targets with a highly symmetric distribution becomes several groups of asymmetrically distributed false targets, breaking the regularity of the original interference and showing a good interference effect.

[0034] Matters not covered by this invention are well-known technologies.

[0035] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0036] The above-described embodiments merely represent several implementation manners of this application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application should be subject to the appended claims.

[0037] ​The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A radar signal receiving and forwarding interference method based on electro-optical phase modulation, characterized in that: include: Build a radar signal receiving and forwarding jammer based on electro-optical phase modulation; The carrier wave emitted by the continuous wave laser is split by the optical fiber beam splitter and then input into the first phase modulator and the second phase modulator respectively; The received radar signal is divided into two paths, one path is input into the first phase modulator, and the other path is input into the second phase modulator after phase modulation by the adjustable electrical phase shifter; The modulation signal output by the first phase modulator is input into the high-speed optical switch, and the control signal controls the high-speed optical switch to switch between on and off to realize intermittent sampling modulation; The modulation signal output by the second phase modulator is input into the adjustable optical phase shifter, and the adjustable optical phase shifter performs phase modulation on the modulation signal; The output signals of the high-speed optical switch and the adjustable optical phase shifter are input into the balanced photodetector via a 90° optical bridge for photoelectric conversion to generate radar jamming signals.

2. A radar signal receiving and forwarding interference method based on electro-optical phase modulation as claimed in claim 1, characterized in that: The radar signal receiving and forwarding jamming device based on electro-optical phase modulation includes a continuous wave laser, a phase modulator, a high-speed optical switch, an adjustable optical phase shifter, a 90° optical bridge, a balanced photoelectric detector, an optical fiber beam splitter, an adjustable electrical phase shifter, an antenna, and a signal generating device; The carrier generated by the continuous wave laser is split by the optical fiber beam splitter and then injected into the input ports of the first phase modulator and the second phase modulator respectively; the radar signal received by the antenna is divided into two paths, one path is input into the RF input port of the first phase modulator, and the other path is input into the RF input port of the second phase modulator after passing through the adjustable electrical phase shifter; the optical signal output by the first phase modulator is input into the balanced photoelectric detector through the 90° optical bridge after passing through the high-speed optical switch; the optical signal output by the second phase modulator is input into the balanced photoelectric detector through the 90° optical bridge after passing through the adjustable optical phase shifter; the balanced photoelectric detector performs photoelectric conversion on the received optical signal and outputs a radar interference signal; The high-speed optical switch is connected with a signal generating device for generating a control signal for controlling intermittent sampling.

3. A radar signal receiving and forwarding interference method based on electro-optical phase modulation as claimed in claim 2, characterized in that: The signal generating device includes a vector signal generator, a function signal generator, an analog signal source, and an arbitrary signal generator.

4. A radar signal receiving and forwarding interference method based on electro-optical phase modulation as claimed in claim 2, characterized in that: The adjustable optical phase shifter and the adjustable electrical phase shifter are both connected with a direct current bias source.

5. The radar signal receiving and forwarding interference method based on electro-optical phase modulation as claimed in claim 2, characterized in that: It also includes a spectrum analyzer, which is connected to the balanced photoelectric detector and is used to observe the spectrum characteristics of the radar interference signal.

6. A radar signal receiving and forwarding interference method based on electro-optical phase modulation as claimed in claim 2, characterized in that: It also includes a power amplifier, which is connected to the balanced photoelectric detector and is used to increase the power of the radar interference signal.

7. A radar signal receiving and forwarding interference method based on electro-optical phase modulation as claimed in claim 2, characterized in that: The continuous wave laser generates a carrier wave with an operating wavelength of 1550 nm.

8. The radar signal receiving and forwarding interference method based on electro-optical phase modulation as claimed in claim 2 is characterized in that: The control signal is a rectangular pulse train.

9. The radar signal receiving and forwarding interference method based on electro-optical phase modulation as claimed in claim 1, characterized in that: When the phase shift of the adjustable electrical phase shifter is 90° and the phase shift of the adjustable optical phase shifter is 0°, the generated false targets are symmetrically distributed, and the amplitudes decrease successively; When the phase shift of the adjustable electrical phase shifter is 90° and the phase shift of the adjustable optical phase shifter is 90°, the generated false targets are distributed asymmetrically.

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