CN116299439A - Ultra-wideband microwave photon imaging radar device - Google Patents

Ultra-wideband microwave photon imaging radar device Download PDF

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Publication number
CN116299439A
CN116299439A CN202310378533.2A CN202310378533A CN116299439A CN 116299439 A CN116299439 A CN 116299439A CN 202310378533 A CN202310378533 A CN 202310378533A CN 116299439 A CN116299439 A CN 116299439A
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optical
microwave photon
filter
respectively connected
ultra
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王党卫
王安乐
刘晓彤
张进
王亚兰
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Air Force Early Warning Academy
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Air Force Early Warning Academy
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/35—Details of non-pulse systems
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)

Abstract

The application relates to an ultra wideband microwave photon imaging radar device, comprising: indoor unit and off-premises station, wherein, the indoor unit includes: the microwave photon receiving and transmitting unit is respectively connected with the data processing module and the outdoor unit. The ultra-wideband microwave photon imaging radar device provided by the invention can generate radar emission waveforms with high frequency band and large bandwidth, stably works, and solves the problems of high cost and huge volume in the traditional electronic technology.

Description

Ultra-wideband microwave photon imaging radar device
Technical Field
The application relates to the field of microwave imaging radar, in particular to an ultra-wideband microwave photon imaging radar device.
Background
Microwave imaging radar plays an increasingly important role in military and civilian applications in its unique ability to provide ultra-long range target imaging throughout the day and under all-weather conditions. Currently, the optimal high-resolution microwave imaging radar based on the traditional microwave electronic technology is a Haystack ultra-wideband satellite imaging radar (HUSIR) proposed by the American Rankine laboratory, and the synthetic bandwidth is 8GHz and W frequency band. However, the high cost and bulk have prevented their use on space-based, on-board or unmanned aerial vehicle platforms. With the rapid development of intelligent recognition technology and accurate defense technology, the extraction of target quantitative information puts higher demands on high-resolution microwave imaging. Increasing bandwidth is an effective way to increase imaging resolution, but traditional electronics techniques have a bottleneck in generating large bandwidth radar waveforms.
The microwave photonics is used as an emerging crossing field combining a microwave electronic technology and an optical technology, and has the advantages of low phase noise, ultra-wideband, low loss, tunability and the like. The microwave photon radar can provide higher signal frequency, faster sampling and processing speed, wider signal and transmission bandwidth, lower reference source noise and transmission loss by taking advantage of electric fineness, flexibility and broadband and low-loss transmission of light, effectively breaks through various technical bottlenecks of a pure electronic system, has the advantages of low power consumption, light weight, small size, electromagnetic interference resistance and the like in combination, and provides an effective path for solving the dilemma of the microwave imaging radar.
In 2014, the university of italian telecommunications union research group reports an all-optical architecture radar for the first time, and on the basis of the all-optical architecture radar, a S, X dual-band microwave photon imaging radar is developed in 2016, and the radar can work simultaneously in dual bands, but the bandwidth is only 18MHz. In 2017, the national university of Qinghua completes a target imaging experiment based on an X-band bandwidth reaching a 4GHz system in a laboratory, and simultaneously, the institute of electronics in China and the university of Nanjing aerospace respectively realize radar emission waveforms with bandwidths reaching 600MHz and 8GHz based on different optical frequency doubling technologies, thereby completing high-precision resolution imaging verification of various targets. In the above schemes, the bandwidth of the transmitted signal is not larger than the bandwidth of the HUSIR. In the conventional radar frequency band, the ultra-wideband radar imaging and system construction based on the microwave photon technology are significant.
To sum up, the prior art has the following problems:
the traditional electronic technology has technical bottlenecks in the aspect of generating high-frequency band and large-bandwidth radar waveforms;
when the traditional electronic technology generates a radar waveform with high frequency band and large bandwidth, the cost is high and the volume is huge;
most of the existing microwave photon imaging radar systems are laboratory systems, stable and durable work is difficult, practicability is to be improved, and key components are high in cost.
Disclosure of Invention
To solve the above technical problems or at least partially solve the above technical problems, the present application provides an ultra wideband microwave photon imaging radar apparatus.
In a first aspect, the present application provides an ultra wideband microwave photon imaging radar apparatus comprising: indoor unit and off-premises station, wherein, the indoor unit includes: the microwave photon receiving and transmitting unit is respectively connected with the data processing module and the outdoor unit; the data processing module comprises: the system comprises a memory and a data acquisition and central control system, wherein the data acquisition and central control system is respectively connected with the memory and the microwave photon receiving and transmitting unit.
Preferably, the microwave photon transceiver unit comprises: the device comprises a DDS signal generator, a frequency divider, a radio frequency transmission matching device, a laser, a first frequency conversion module, an optical combination filter amplification module, a first optical coupler, an adjustable optical delay line, a second photoelectric detector and an intermediate frequency electric filter, wherein the DDS signal generator is respectively connected with the frequency divider, the radio frequency transmission matching device and a data acquisition and central control system in a data processing module, the frequency divider is connected with the data acquisition and central control system, the first frequency conversion module is respectively connected with the radio frequency transmission matching device, the laser and the optical combination filter amplification module, the first optical coupler is respectively connected with an outdoor unit, the adjustable optical delay line and the optical combination filter amplification module, the adjustable optical delay line is connected with the outdoor unit, the second photoelectric detector is respectively connected with the outdoor unit and the intermediate frequency electric filter, and the intermediate frequency electric filter is connected with the data acquisition and central control system.
Preferably, the microwave photon transceiver unit further comprises: the first power supply module is respectively connected with the DDS signal generator, the frequency divider, the radio frequency transmission matching device, the laser, the first frequency conversion module, the optical combination filtering amplification module and the first optical coupler.
Preferably, the outdoor unit includes: the device comprises a first optical amplifier, a first photoelectric detector, a second frequency conversion module, an electric filter, a low-noise amplifier, a power amplifier, a receiving antenna and a transmitting antenna, wherein the first optical amplifier is respectively connected with a tunable optical delay line in a microwave photon receiving and transmitting unit and the second frequency conversion module, the second frequency conversion module is respectively connected with a second photoelectric detector in the microwave photon receiving and transmitting unit and the low-noise amplifier, the first photoelectric detector is respectively connected with a first optical coupler in the microwave photon receiving and transmitting unit and the electric filter, the power amplifier is respectively connected with the electric filter and the transmitting antenna, and the low-noise amplifier is connected with the receiving antenna.
Preferably, the outdoor unit further includes: the second power supply module is respectively connected with the first optical amplifier, the first photoelectric detector, the second frequency conversion module, the electric filter, the low noise amplifier, the power amplifier, the receiving antenna and the transmitting antenna.
Preferably, the first frequency conversion module includes: the optical coupler comprises a Mach-Zehnder modulator, an optical coupler and an electric control bias point controller, wherein the electric control bias point controller is respectively connected with the Mach-Zehnder modulator and the optical coupler, and the Mach-Zehnder modulator is connected with the optical coupler.
Preferably, the second frequency conversion module includes: the optical coupler comprises a Mach-Zehnder modulator, an optical coupler and an electric control bias point controller, wherein the electric control bias point controller is respectively connected with the Mach-Zehnder modulator and the optical coupler, and the Mach-Zehnder modulator is connected with the optical coupler.
Preferably, the second frequency conversion module includes: a phase modulator and a tunable optical filter, wherein the phase modulator and the tunable optical filter are connected.
Preferably, the optical combination filtering amplification module includes: the optical amplifier is respectively connected with the double-band-pass optical filter and the band-pass optical filter.
Preferably, the optical combination filtering amplification module includes: the optical amplifier is respectively connected with the band-stop optical filter and the band-pass optical filter.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
the ultra-wideband microwave photon imaging radar device provided by the invention can generate radar emission waveforms with high frequency band and large bandwidth, stably works, and solves the problems of high cost and huge volume in the traditional electronic technology.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
Fig. 1 is a schematic diagram of an ultra wideband microwave photon imaging radar device according to an embodiment of the present application;
fig. 2 is a schematic diagram of an ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
Fig. 3 is a schematic diagram of a first embodiment of a frequency conversion module of an ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
Fig. 4 is a schematic diagram of a second embodiment of a frequency conversion module of an ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
Fig. 5 is a schematic diagram of a first embodiment of an optical combination filter amplifying module of an ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
Fig. 6 is a schematic diagram of a second embodiment of an optical combination filter amplifying module of an ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
Fig. 7 is a ±3-order sideband spectrogram output by the optical combination filtering amplification module during an experiment of the ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
Fig. 8 is a spectrum diagram of a transmission signal generated by a transmitter of an ultra-wideband microwave photon imaging radar system during an experiment of the ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
Fig. 9 is a signal spectrum diagram of an ultra-wideband microwave photon imaging radar system receiver after mixing during an experiment of the ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.
Fig. 1 is a schematic diagram of an ultra-wideband microwave photon imaging radar device according to an embodiment of the present application.
As shown in fig. 1, the invention provides an ultra-wideband microwave photon imaging radar device, which comprises an indoor unit and an outdoor unit, wherein the indoor unit mainly comprises a microwave photon receiving and transmitting unit and a data processing module.
The microwave photon receiving and transmitting unit mainly comprises a first power supply module, a DDS (direct digital frequency synthesis) signal generator, a frequency divider, a laser, a radio frequency transmission matching device, a first frequency conversion module, an optical combination filter amplifier, a first optical coupler, an adjustable optical delay line, a second photoelectric detector and an intermediate frequency electric filter. The data processing module mainly comprises a data acquisition and central control system and a memory. The outdoor unit mainly comprises a power supply module, a first photoelectric detector, an electric filter, a power amplifier, a transmitting antenna, a first optical amplifier, a second frequency conversion module, a low noise amplifier and a receiving antenna.
In the microwave photon receiving and transmitting unit, a first power supply module is used for providing power supplies required by a laser, a DDS signal generator and an optical combination filtering and amplifying module; the DDS signal generator is divided into three paths, one path is used as a modulation signal of the first frequency conversion module, the other path is used as a reference signal, and the other path generates a clock signal through a frequency divider, wherein the reference signal and the clock signal are both input to the data acquisition and central control system; the laser generates a single-frequency continuous optical signal as a carrier wave of the frequency conversion module; the radio frequency transmission matching device is used for realizing matching transmission of radio frequency signals between the DDS output and the modulator; the first frequency conversion module is used for completing up-conversion of signals; the optical combination filtering and amplifying module is used for completing the filtering of the required optical edge band and the amplifying of the optical signal after the filtering; the first optical coupler divides an input optical signal into two paths, one path of the optical signal is sent to the first photoelectric detector, and the other path of the optical signal is sent to the optical adjustable delay line to serve as a local oscillation signal of the receiving end; the tunable optical delay line completes the delay of the broadband optical local oscillation signal; the second photoelectric detector completes photoelectric conversion of the intermediate frequency signal after down-conversion; the intermediate frequency electric filter completes the filtering of the intermediate frequency signal.
And the data processing module completes the quantized acquisition processing of the electric signal after the echo signal is subjected to down-conversion.
In the outdoor unit, the power module provides power required by the power amplifier, the first optical amplifier and the low noise amplifier; the transmitting antenna and the receiving antenna respectively complete the transmission of radio frequency signals and the reception of echo signals; the first photoelectric detector converts an input optical sideband signal into an electric signal; the electric filter filters the electric signal and filters unnecessary stray signals; the power amplifier amplifies the electric signal to reach the power suitable for transmitting; the low noise amplifier completes the amplification of echo signals; the second frequency conversion module is used for completing the down conversion of the received signal; the first optical amplifier amplifies an input optical signal to a constant power.
The implementation method of the ultra-wideband microwave photon imaging radar provided by the application comprises the following steps:
1. composition of the composition
The schematic diagram of the ultra-wideband microwave photon imaging radar device is shown in fig. 2, and the device can be divided into a transmitter and a receiver according to the function implementation. Wherein the transmitter comprises: the device comprises a laser, a first frequency conversion module, a DDS signal generator, a radio frequency transmission matching device, an optical combination filter amplifier, a first optical coupler, a first photoelectric detector, an electric filter, a power amplifier and a transmitting antenna; the receiver comprises a receiving antenna, a low-noise amplifier, an adjustable optical delay line, a first optical amplifier, a second frequency conversion module, a receiving antenna, a low-noise amplifier, a second photoelectric detector, an intermediate frequency electric filter and a data processing module. It should be noted that the radio frequency transmission matching device may be attached to the modulator in the first frequency conversion module, the DDS, or a radio frequency line connected to both, depending on the specific implementation, to achieve matching transmission of the radio frequency signal between the DDS output and the modulator. The radio frequency transmission matching device shown in fig. 2 is attached to a radio frequency line where the modulator is connected to the DDS, and the other two modes are not shown in the figure.
In a first implementation, the first frequency conversion module and the second frequency conversion module each use a structure as shown in fig. 3. The frequency conversion module shown in fig. 3 includes a mach-zehnder modulator, an optical coupler, and an electrically controlled bias point controller.
In a second implementation, the first frequency conversion module uses the structure shown in fig. 3, and the second frequency conversion module uses the structure shown in fig. 4. The frequency conversion module shown in fig. 4 includes a phase modulator, a tunable optical filter. Compared with the frequency conversion module in fig. 3, the frequency conversion module in fig. 4 has the advantages that an electric control bias point controller is not needed, and signals are more stable.
Based on any implementation method, the optical combination filter amplifying module of the transmitter may have a structure as shown in fig. 5 or a structure as shown in fig. 6.
The optical combiner filter amplification module of fig. 5 includes a dual bandpass optical filter, an optical amplifier, and a bandpass filter. It is specifically noted that: the minimum bandwidth that laboratory current dual band-pass optical filter can set up is 10GHz, and out-of-band rejection ratio is 40dB, along with the development of future state of the art, when dual band-pass optical filter's bandwidth is littleer, out-of-band rejection ratio is higher, can only adopt a dual band-pass optical filter.
The optical combiner filter amplification module of fig. 6 includes a band reject filter, an optical amplifier, and a bandpass filter.
Preferably, the optical filter used in the system is any one of a fiber grating or a programmable optical filter or other optical filter. In particular, in order to achieve miniaturization of the system, the optical filter can be used for replacing a programmable optical filter (25 ten thousand yuan) by customizing a device (2000 yuan) with a specific specification, so that not only can the miniaturization of the system be achieved, but also the cost can be greatly reduced.
Furthermore, in order to realize the integration of the system, by combining the photoelectric hybrid integration technology, a laser, an electro-optical modulator, an optical filter, a photoelectric detector, a radio frequency amplifier and an electric signal source can be partially or completely integrated into one module or chip, so that the system has smaller volume and is used on an air-based, satellite-borne or unmanned plane platform.
2. Connection relation and connection mode
In the transmitter, the output port of the laser is connected with the optical input port of the modulator (mach-zehnder modulator in fig. 3 or phase modulator in fig. 4) in the first frequency conversion module in an optical waveguide connection mode, the output port of the DDS signal generator is connected with the radio frequency input port of the modulator in the first frequency conversion module in an radio frequency waveguide connection mode, the optical output port of the frequency conversion module is connected with the input port of the optical combination filter amplification module in an optical waveguide connection mode, the output port of the optical combination filter amplification module is connected with the input port of the first optical coupler in an optical waveguide connection mode, one of the output ports of the first optical coupler is connected with the optical input port of the first photoelectric detector in an optical waveguide connection mode, the radio frequency output port of the first photoelectric detector is connected with the input port of the electric filter in an radio frequency waveguide connection mode, and the output port of the electric filter is connected with the interface of the transmitting antenna in an radio frequency waveguide connection mode.
In the receiver, the other output port of the first optical coupler is connected with the input port of the adjustable optical delay line in an optical waveguide connection mode, the output port of the adjustable optical delay line is connected with the input port of the first optical amplifier in an optical waveguide connection mode, the output port of the optical amplifier is connected with the optical input port of the modulator in the second frequency conversion module in an optical waveguide connection mode, the interface of the receiving antenna is connected with the input port of the low noise amplifier in an RF waveguide connection mode, the output port of the low noise amplifier is connected with the RF input port of the modulator in the second frequency conversion module in an RF waveguide connection mode, the optical output port of the frequency conversion module is connected with the optical input port of the second photoelectric detector in an optical waveguide connection mode, the RF output port of the second photoelectric detector is connected with the input port of the intermediate frequency electric filter in an RF waveguide connection mode, and the output port of the intermediate frequency electric filter is connected with the interfaces of the data acquisition system and the central control system.
In the frequency conversion module shown in fig. 3, the output port of the mach-zehnder modulator is connected with the input port of the optical coupler in an optical waveguide connection mode, one output port of the optical coupler is used as an optical output port of the frequency conversion module, the other output port of the optical coupler is connected with the input port of the electric control bias point controller in an optical waveguide connection mode, and the output port of the electric control bias point controller is connected with the bias voltage input port of the mach-zehnder modulator.
In the frequency conversion module shown in fig. 4, the output port of the phase modulator is connected with the input port of the tunable optical filter in an optical waveguide connection manner, and the output port of the tunable optical filter is used as an optical output port of the frequency conversion module.
In the optical combination filter amplifying module shown in fig. 5, the output port of the dual-band optical filter is connected with the input port of the optical amplifier in an optical waveguide connection mode, and the output port of the optical amplifier is connected with the input port of the band-pass optical filter in an optical waveguide connection mode, and the output port of the band-pass optical filter is used as the optical output port of the frequency conversion module.
In the optical combination filter amplifying module shown in fig. 6, the output port of the band-stop optical filter is connected with the input port of the optical amplifier in an optical waveguide connection mode, the output port of the optical amplifier is connected with the input port of the band-pass optical filter in an optical waveguide connection mode, and the output port of the band-pass optical filter is used as the optical output port of the frequency conversion module.
3. Principle of
(1) Transmitter
In the transmitter, a laser outputs a single-frequency continuous optical signal as an original carrier wave to be input to an optical input port of a Mach-Zehnder modulator in a first frequency conversion module, and the frequency is recorded as f 0 . The DDS signal generator generates a center frequency f 1 Bandwidth of B 1 Is loaded to the radio frequency input port of the Mach-Zehnder modulator. The output of the Mach-Zehnder modulator enters the optical coupler, one path of the output is used as the output of the first frequency conversion module, and the other path of the output is used as the input of the electric control bias point controller. Further, by changing the output power of the DDS signal generator, the signal to noise ratio of the + -1-order optical sidebands is suppressed, the modulation index is equal to 3.8314, the signals output by the modulator only keep the odd-order optical sidebands of + -3-order or above, and the signal to noise ratio of the + -3-order optical sidebands is highest. Here, the modulation index=pi×dds is the output voltage of the radio frequency signal generated by the mach-zehnder modulator.
In order to obtain an + -3-order optical sideband, the output of the first frequency conversion module enters the optical combination filtering amplification module. If the optical combination filtering and amplifying module adopts the structure shown in fig. 5, firstly, inhibiting the + -1-order optical sidebands through the double-band optical filter, and then inhibiting the + -5-order and higher-order odd-order optical sidebands through the band-pass optical filter; if the optical combination filtering and amplifying module adopts the structure shown in fig. 6, the optical sideband of + -1 order is firstly inhibited by the band-stop optical filter, and then the optical sideband of + -5 order and higher odd order is inhibited by the band-pass optical filter.
The output of the optical combination filtering and amplifying module enters a first optical coupler, one path of output enters a first photoelectric detector to finish the conversion from an optical signal to an electric signal, and the center frequency of the generated electric signal is 6f 1 Bandwidth of 6B 1 The generated electric signal enters the working range at a specific frequency f 2 ～f 3 To suppress unnecessary spurious signals to obtain a clean center frequency of 6f 1 Wherein f is 1 、f 2 、f 3 A certain relationship needs to be satisfied: f (f) 2 ≤6f 1 +3B 1 ，f 3 ≥6f 1 +3B 1 . Finally, the electric signal is amplified by a power amplifier and is transmitted out through a transmitting antenna; the other path of output enters an optical adjustable delay line and is used as a local oscillation signal of the receiver.
In summary, in the transmitter, through the first frequency conversion module and the optical combination filtering amplification module, the center frequency of the generated electric signal is 6 times of the center frequency of the electric signal generated by the original DDS, and the bandwidth is 6 times of the bandwidth of the original electric signal, which indicates that the system has the capability of generating a frequency-six wide spectrum signal, and overcomes the technical bottleneck of the traditional electronic technology in the aspect of generating a high-frequency-band and large-bandwidth radar waveform.
(2) Receiver with a receiver body
The output of the adjustable light delay line enters the optical amplifier, the optical amplifier adopts a constant power mode to amplify to a certain power, and the constant power mode is sent to the optical input port of the second frequency conversion module. And receiving a target echo signal received by the antenna, entering a low noise amplifier, and enabling the amplified signal to enter a radio frequency input port of a modulator in the second frequency conversion module. And the output optical signal of the second frequency conversion module is sent to the second photoelectric detector to generate an intermediate frequency signal carrying target information, and the intermediate frequency signal enters the intermediate frequency electric filter to complete the filtering and then enters the data processing module to complete the quantized acquisition processing of the electric signal. If the second frequency conversion module adopts the structure shown in fig. 3, the mach-zehnder modulator needs to be controlled to work in an orthogonal state; if the second frequency conversion module adopts the structure shown in fig. 4, a tunable optical filter is used to filter out all optical sidebands on one side of the modulated carrier wave, so as to realize optical deskew.
It should be noted that, in the receiver, the low-loss tunable optical delay line is used to delay the broadband optical local oscillation signal, and the detection of the targets in different distance ranges in space is matched by switching the extension lines with different lengths, so that the requirement of the mixing and miter-removing echo receiving process on the sampling rate of the analog-to-digital converter is reduced.
Examples
Taking an implementation method as an example, an experimental system is built, and the experimental data are combined to specifically explain:
the first frequency conversion module and the second frequency conversion module adopted by the ultra-wideband microwave photon imaging radar system in the experiment are both in the structure shown in fig. 3, and the optical combination filtering amplification module is in the structure shown in fig. 5.
In order to verify that the ultra-wideband microwave photon imaging radar system can realize the generation of six-frequency-multiplication wide spectrum signals, a waveform generation and measurement experiment is carried out on a transmitter. Setting the central wavelength of a laser to 1549.91nm, setting the frequency of a DDS transmitting signal to 5.833GHz, and adjusting the output power of a DDS signal generator to enable the Mach-Zehnder modulator to be in a first-order sideband suppression state; the center wavelength of the dual-band optical filter is 1549.77 nm and 1550.05nm, the center wavelength and the bandwidth of the optical band optical filter are 1549.91nm and 40GHz respectively, and the output spectrum after combined filtering is shown in fig. 7. As can be seen from the test results, when the mach-zehnder modulator works in the states of carrier suppression and even-order sideband suppression, the third-order-carrier suppression ratio can reach 50dB, the third-order-first-order suppression ratio can reach 39dB under the action of the optical combination filter amplification module, and the spectrum can generate an electric signal with a better signal-to-noise ratio after being subjected to beat frequency by the first photoelectric detector, as shown in fig. 8. Fig. 8 (a) and (b) are signal frequency spectra of DDS output signal bandwidths corresponding to 1.66GHz and 166MHz, respectively. As can be seen from the experimental results, the center frequency of the system transmitting signal is 35GHz, which is consistent with the theoretical value, when the bandwidth of the DDS transmitting signal is 1.66GHz, the bandwidth of the generated transmitting signal is 9.88GHz (the bandwidth is larger than the bandwidth of HUSIR and the bandwidths in references [1] to [5 ]), the frequency spectrum amplitude fluctuates by +/-5 dB, and the waveform signal-to-noise ratio reaches 45dB; when the DDS transmitting signal bandwidth is 166MHz, the generated transmitting signal bandwidth is 0.98GHz, the frequency spectrum amplitude fluctuates by +/-2.5 dB, and the waveform signal-to-noise ratio reaches 35dB. The system has the capability of generating a frequency-six-multiplication wide spectrum signal by integrating the experimental results.
To verify the operational capabilities of the system, a self-closed loop experiment of the system has been completed. And directly loading the electric signal generated by the first photoelectric detector to a Mach-Zehnder modulator in a second frequency conversion module of the receiver, and realizing closed loop by the system. The frequency of the output signal after the frequency mixing of the receiver is proportional to the delay of the adjustable optical fiber delay line, so that by changing the delay of the adjustable optical fiber delay line, the second photoelectric detector outputs signals with different frequencies. Fig. 9 is a graph of the output signal after mixing by a receiver with varying fiber delay line length (delay time) when the transmitter transmits signal bandwidths of 10GHz and 100MHz, respectively. As can be seen from the experimental results, the frequency after the ultra wideband radar system receiver mixes the signal is proportional to the length (delay time) of the fiber delay line, and is consistent with the expected result.
The ultra-wideband microwave photon imaging radar device provided by the invention can generate radar emission waveforms with high frequency band and large bandwidth, stably works, and solves the problems of high cost and huge volume in the traditional electronic technology:
(1) In the transmitter, the center frequency of the generated electric signal is 6 times of the center frequency of the electric signal generated by the original DDS through the first frequency conversion module and the optical combination filtering amplification module, the bandwidth is 6 times of the bandwidth of the original electric signal, and the technical bottleneck of the traditional electronic technology in the aspect of generating the high-frequency-band and large-bandwidth radar waveform is overcome.
(2) In the receiver, the low-loss adjustable optical delay line is utilized to delay the broadband optical local oscillation signal, the detection of targets in different distance ranges in space is matched by switching the extension lines with different lengths, and the requirement of the mixing frequency to the sampling rate of the analog-to-digital converter in the process of obliquely receiving the echo is reduced.
(3) The optical filters used in the system can be used for replacing the programmable optical filter (25 ten thousand yuan) by customizing a device (2000 yuan) with a specific specification, so that the miniaturization of the system can be realized, and the cost can be greatly reduced.
(4) By combining the photoelectric hybrid integration technology, a laser, an electro-optical modulator, an optical filter, a photoelectric detector, a radio frequency amplifier and an electric signal source can be partially or completely integrated into one module or chip, so that the system has smaller volume and is used on an air-based, satellite-borne or unmanned plane platform.
It should be noted that in this document, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The ultra-wideband microwave photon imaging radar device is characterized by comprising an indoor unit and an outdoor unit, wherein the indoor unit comprises a data processing module and a microwave photon receiving and transmitting unit, the microwave photon receiving and transmitting unit is respectively connected with the data processing module and the outdoor unit, the data processing module comprises a memory and a data acquisition and central control system, and the data acquisition and central control system is respectively connected with the memory and the microwave photon receiving and transmitting unit.
2. The ultra-wideband microwave photon imaging radar apparatus of claim 1, wherein the microwave photon transceiver unit comprises: the device comprises a DDS signal generator, a frequency divider, a radio frequency transmission matching device, a laser, a first frequency conversion module, an optical combination filter amplification module, a first optical coupler, an adjustable optical delay line, a second photoelectric detector and an intermediate frequency electric filter, wherein the DDS signal generator is respectively connected with the frequency divider, the radio frequency transmission matching device and a data acquisition and central control system in a data processing module, the frequency divider is connected with the data acquisition and central control system, the first frequency conversion module is respectively connected with the radio frequency transmission matching device, the laser and the optical combination filter amplification module, the first optical coupler is respectively connected with an outdoor unit, the adjustable optical delay line and the optical combination filter amplification module, the adjustable optical delay line is connected with the outdoor unit, the second photoelectric detector is respectively connected with the outdoor unit and the intermediate frequency electric filter, and the intermediate frequency electric filter is connected with the data acquisition and central control system.
3. The ultra-wideband microwave photon imaging radar apparatus of claim 2, wherein the microwave photon transceiver unit further comprises: the first power supply module is respectively connected with the DDS signal generator, the frequency divider, the radio frequency transmission matching device, the laser, the first frequency conversion module, the optical combination filtering amplification module and the first optical coupler.
4. The ultra-wideband microwave photon imaging radar apparatus as claimed in claim 3, wherein the outdoor unit includes: the device comprises a first optical amplifier, a first photoelectric detector, a second frequency conversion module, an electric filter, a low-noise amplifier, a power amplifier, a receiving antenna and a transmitting antenna, wherein the first optical amplifier is respectively connected with a tunable optical delay line in a microwave photon receiving and transmitting unit and the second frequency conversion module, the second frequency conversion module is respectively connected with a second photoelectric detector in the microwave photon receiving and transmitting unit and the low-noise amplifier, the first photoelectric detector is respectively connected with a first optical coupler in the microwave photon receiving and transmitting unit and the electric filter, the power amplifier is respectively connected with the electric filter and the transmitting antenna, and the low-noise amplifier is connected with the receiving antenna.
5. The ultra-wideband microwave photon imaging radar apparatus as claimed in claim 4, wherein the outdoor unit further comprises: the second power supply module is respectively connected with the first optical amplifier, the first photoelectric detector, the second frequency conversion module, the electric filter, the low noise amplifier, the power amplifier, the receiving antenna and the transmitting antenna.
6. The ultra-wideband microwave photon imaging radar apparatus of claim 5, wherein the first frequency conversion module comprises: the optical coupler comprises a Mach-Zehnder modulator, an optical coupler and an electric control bias point controller, wherein the electric control bias point controller is respectively connected with the Mach-Zehnder modulator and the optical coupler, and the Mach-Zehnder modulator is connected with the optical coupler.
7. The ultra-wideband microwave photon imaging radar apparatus of claim 6, wherein the second frequency conversion module comprises: the optical coupler comprises a Mach-Zehnder modulator, an optical coupler and an electric control bias point controller, wherein the electric control bias point controller is respectively connected with the Mach-Zehnder modulator and the optical coupler, and the Mach-Zehnder modulator is connected with the optical coupler.
8. The ultra-wideband microwave photon imaging radar apparatus of claim 6, wherein the second frequency conversion module comprises: a phase modulator and a tunable optical filter, wherein the phase modulator and the tunable optical filter are connected.
9. The ultra-wideband microwave photonic image radar apparatus of claim 7 or 8, the optical combining filter amplification module comprising: the optical amplifier is respectively connected with the double-band-pass optical filter and the band-pass optical filter.
10. The ultra-wideband microwave photon imaging radar apparatus of claim 7 or 8, the optical combining filter amplification module comprising: the optical amplifier is respectively connected with the band-stop optical filter and the band-pass optical filter.
CN202310378533.2A 2023-04-04 2023-04-04 Ultra-wideband microwave photon imaging radar device Pending CN116299439A (en)

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