A microwave photon multi-band radar transmitting device and system

Abstract

The present invention discloses a microwave photon multi-band radar transmitting device and system, which includes: a laser, an optical frequency conversion module, a first optical coupler, a first photodetector and a bandpass electric filter. The optical frequency conversion module performs phase modulation and filtering on the original carrier output by the laser to obtain p pairs of bandwidth nB 1 The first optical coupler divides the optical signal output by the optical frequency conversion module into two paths, one path is input to the first photodetector, and the other path is output to the radar receiving device as a reference optical signal; the first photodetector converts p pairs of bandwidth nB 1 The optical sideband pairs are converted into RF signals, including: 2p‑1 with a bandwidth of 2nB 1 characteristic frequency band; a passband electric filter filters out radio frequency signals of M different frequency bands, where M is an integer greater than or equal to 2, and outputs the radio frequency signals of each frequency band from independent channels, thereby simultaneously obtaining broadband radar transmission signals of multiple frequency bands.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a microwave photon multi-band radar transmitting device and system. Background Art

[0002] Radar is an extremely important weapon and equipment in military warfare. It is mainly responsible for the detection, imaging, identification, tracking, and guidance of targets. It has the characteristics of all-day and all-weather, and can obtain battlefield information in real time. With the development of radar technology and equipment in various countries around the world, the weapons and equipment and combat tactics to deal with existing radars have also made great progress. The development of equipment and tactics such as low-altitude penetration, high-altitude attacks, rapid strikes, false targets, small arms, stealth equipment, electronic countermeasures, and battlefield environments have brought huge threats to existing radars. This requires existing radars to have a larger range of action, faster response speed, higher recognition accuracy, wider working frequency bands, and more operating modes to deal with these threats. Traditional radars using electronic technology require an independent hardware system to achieve a certain function or a certain frequency band. In order to achieve multi-functional or multi-band functions, the commonly used method is based on the upgrade and combination of various existing single-function radars, which inevitably causes problems such as large radar size, complex structure, and difficult maintenance that limit the use of scenarios. Summary of the invention

[0003] The embodiments of the present invention provide a microwave photon multi-band radar transmitting device and system, which can simultaneously obtain broadband radar transmission signals of multiple frequency bands, which is beneficial to improving the problem of excessive radar size while enriching radar functions.

[0004] In a first aspect, an embodiment of the present invention provides a microwave photon multi-band radar transmitting device, including:

[0005] A laser, used for outputting a continuous optical signal as an original carrier;

[0006] The optical frequency conversion module is used to perform phase modulation and filtering on the original carrier to obtain p pairs of bandwidth nB 1 The optical sideband pair, where p is an integer greater than or equal to 2, nB 1 is greater than zero, the optical sideband whose frequency after phase modulation is closest to the original carrier frequency is the m-th order optical sideband, and the p pairs of optical sideband pairs include: the m-th order to the m+p-1-th order optical sidebands generated after the phase modulation;

[0007] A first optical coupler, used to divide the optical signal output by the optical frequency conversion module into two paths, one path is input into the first photodetector, and the other path is output as a reference optical signal to the radar receiving device;

[0008] The first photodetector is used to convert the p pairs of bandwidth to nB 1 The optical sideband pair is converted into a radio frequency signal, the radio frequency signal includes: 2p-1 bandwidth is 2nB 1 characteristic frequency bands; and

[0009] The bandpass electric filter is used to filter out radio frequency signals of M different frequency bands from the 2p-1 characteristic frequency bands, and output the radio frequency signals of each frequency band from independent channels to transmit them to the transmitting antenna of the corresponding frequency band, wherein M is an integer greater than or equal to 2.

[0010] Furthermore, the optical frequency conversion module comprises:

[0011] The first phase modulator is connected to the laser and is used to modulate the original carrier output by the laser through a first modulation signal input by a first microwave signal source of an external device, wherein the bandwidth of the first modulation signal is B 1 ;

[0012] A dual-bandpass optical filter connected to the output end of the first phase modulator, used for filtering the optical signal after the first modulation to filter out the n-th order optical sideband pair therein;

[0013] A second phase modulator is connected to the output end of the dual-bandpass optical filter and is used to phase modulate the optical signal filtered out by the dual-bandpass optical filter through a second modulation signal input by an external second microwave signal source;

[0014] The bandpass optical filter is connected to the output end of the second phase modulator and is used to filter the optical signal obtained after the second modulation to filter out the p pairs of optical signals with a bandwidth of nB. 1 The light sideband pair.

[0015] Furthermore, the optical frequency conversion module further includes:

[0016] a first optical amplifier, connected between the dual-bandpass optical filter and the second phase modulator, and configured to amplify the optical signal filtered out by the dual-bandpass optical filter;

[0017] The second optical amplifier is connected between the bandpass optical filter and the first optical coupler, and is used to amplify the optical signal filtered out by the bandpass optical filter.

[0018] Furthermore, the bandwidth of the bandpass optical filter satisfies the following conditions:

[0019] 2(p-1)f 2 -2(nf 1 -mf 2 )+nB 1 <Bf <2pf 2 -2(nf 1 -mf 2 )-nB 1

[0020] Among them, B f represents the bandwidth of the bandpass optical filter, f 1 is the center frequency of the first modulation signal, f 2 is the center frequency of the second modulation signal.

[0021] Furthermore, p is equal to 2, and there are three characteristic frequency bands, and the center frequencies of the three characteristic frequency bands are respectively:

[0022] f 2 -2(nf 1 -mf 2 ), 2|nf 1 -mf 2 |, 2f 2 -2(nf 1 -mf 2 ).

[0023] Furthermore, the above-mentioned radar transmitting device also includes: a power amplifier, the input end of the power amplifier is connected to the output end of the bandpass electric filter, and is used to power amplify the radio frequency signals of each frequency band output by the bandpass electric filter, and the output end of the power amplifier is used to connect to the transmitting antenna of the corresponding frequency band.

[0024] In a second aspect, an embodiment of the present invention provides a microwave photon multi-band radar system, comprising: M transmitting antennas, M receiving antennas, a radar receiving device, and the radar transmitting device provided in the first aspect above;

[0025] The radar transmitting device is connected to the M transmitting antennas respectively, and the frequency bands of the M radio frequency signals output by the radar transmitting device correspond one-to-one to the transmitting frequency bands of the M transmitting antennas;

[0026] The radar receiving device is connected to the M receiving antennas respectively, and the receiving frequency bands of the M receiving antennas correspond one-to-one to the transmitting frequency bands of the M transmitting antennas.

[0027] Further, M is equal to 2.

[0028] Furthermore, the radar receiving device includes: an optical delay line, an electrical coupler, a first low noise amplifier, a Mach-Zehnder modulator, a bias point controller, a second optical coupler, a second photodetector, an intermediate frequency filter, and a signal processor for extracting target information from a received signal.

[0029] The optical delay line is respectively connected to the Mach-Zehnder modulator and the first optical coupler in the radar transmitting device;

[0030] The Mach-Zehnder modulator is also respectively connected to the output end of the bias point controller, the input end of the second optical coupler and the output end of the first low-noise amplifier, the input end of the first low-noise amplifier is connected to the output end of the electrical coupler, the input end of the electrical coupler is connected to the M receiving antennas, the first output end of the second optical coupler is connected to the signal processor via the second photodetector and the intermediate frequency filter in sequence, and the second output end of the second optical coupler is connected to the input end of the bias point controller.

[0031] Furthermore, the radar receiving device further includes: a second low-noise amplifier, an input end of the second low-noise amplifier is connected to the second photodetector, and an output end of the second low-noise amplifier is connected to the intermediate frequency filter.

[0032] The microwave photon multi-band radar transmitting device and system provided in the embodiment of the present invention performs phase modulation and filtering on the original carrier through the optical frequency conversion module to obtain p pairs of bandwidth nB 1 The optical sideband pair, where p is an integer greater than or equal to 2, nB 1 The optical sideband with the frequency closest to the original carrier frequency after phase modulation is the m-th order optical sideband, and the p pairs of optical sidebands include: the m-th to m+p-1-th order optical sidebands generated after phase modulation, and then the first photodetector is used to convert the p pairs of optical sidebands with a bandwidth of nB 1 The optical sideband pairs are converted into radio frequency signals, and the bandpass electric filter filters out M (M is an integer greater than or equal to 2) radio frequency signals of different frequency bands from 2p-1 characteristic frequency bands, and outputs the radio frequency signals of each frequency band from independent channels to be transmitted to the transmitting antenna of the corresponding frequency band for transmission. In this way, broadband radar transmission signals of multiple frequency bands can be obtained at the same time, which is conducive to enriching the radar functions while improving the problem of excessive radar size. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 A schematic diagram of the structure of a radar transmitting device provided by a first aspect of an embodiment of the present invention is shown;

[0035] Figure 2A schematic diagram of a spectrum of an optical signal emitted by a laser in an embodiment of the present invention is shown;

[0036] Figure 3 A schematic diagram of the structure of an optical frequency conversion module in an embodiment of the present invention is shown;

[0037] Figure 4 A schematic diagram of the spectrum of the optical signal selected by the dual-bandpass optical filter in an embodiment of the present invention is shown;

[0038] Figure 5 A schematic diagram of the spectrum of an optical signal selected by a bandpass optical filter in an embodiment of the present invention is shown;

[0039] Figure 6 A schematic diagram showing the spectrum of the radio frequency signal output by the first photodetector in an embodiment of the present invention is shown;

[0040] Figure 7 A schematic diagram of the structure of a radar system provided by a second aspect of an embodiment of the present invention is shown;

[0041] Figure 8 The spectrum diagram of radar transmission signals with center frequencies of 11.5003 GHz and 15.6426 GHz generated by the radar transmitting device in the embodiment of the present invention is shown;

[0042] Fig. 9 The normalized power spectrum of the intermediate frequency signal obtained after the radar receiving device in the embodiment of the present invention performs de-skewing processing on the echo signal is shown. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure. Herein, the term "plurality" includes two or more than two.

[0044] In a first aspect, an embodiment of the present invention provides a microwave photon multi-band radar transmitting device, such as Figure 1 As shown, the radar transmitting device 10 includes: a laser 101 , an optical frequency operation module 102 (OFOM), a first optical coupler 103 , a first photodetector 104 and a bandpass electric filter 105 .

[0045] The laser 101 is used to output a continuous optical signal as the original carrier. The laser 101 is a single-frequency laser, and its output frequency is denoted as f 0 ,like Figure 2 shown.

[0046] The optical frequency conversion module 102 is used to perform phase modulation and filtering on the original carrier to obtain p pairs of bandwidth nB 1 Where p is an integer greater than or equal to 2, nB 1 Greater than zero. The frequency after phase modulation is closest to the original carrier frequency f 0 The optical sideband is an m-th order optical sideband, and the p pairs of optical sideband pairs include: the m-th order to the m+p-1-th order optical sidebands generated after the phase modulation.

[0047] In some examples, such as Figure 3 As shown, the optical frequency conversion module 102 may include: a first phase modulator 1021, a dual-bandpass optical filter 1022, a second phase modulator 1024, and a bandpass optical filter 1025. The laser 101 is connected to the signal input end of the first phase modulator 1021 by means of an optical waveguide connection. The signal output end of the first phase modulator 1021 is connected to the input end of the dual-bandpass optical filter 1022 by means of an optical waveguide connection. The output end of the dual-bandpass optical filter 1022 is connected to the signal input end of the second phase modulator 1024, and the signal output end of the second phase modulator 1024 is connected to the input end of the bandpass optical filter 1025 by means of an optical waveguide connection.

[0048] In addition, the first phase modulator 1021 is connected to the first microwave signal source 12 by means of a radio frequency waveguide connection. The first microwave signal source 12 provides the first phase modulator 1021 with a first modulation signal. For example, the first modulation signal may be a low-frequency narrowband signal, and the center frequency and bandwidth of the low-frequency narrowband signal are respectively f 1 and B 1 .f 1 and B 1 It can be determined according to the needs of the actual application scenario.

[0049] The second phase modulator 1024 is connected to the second microwave signal source 13 by means of a radio frequency waveguide. The second microwave signal source 13 provides a second modulation signal to the second phase modulator 1024. For example, the second modulation signal may be another single frequency signal, and the frequency of the single frequency signal is denoted as f 2 .f 2 It can be determined according to the needs of the actual application scenario.

[0050] When used specifically, the laser 101 outputs an optical signal, that is, an original carrier, which enters the first phase modulator 1021. The first phase modulator 1021 performs phase modulation on the original carrier through the first modulation signal. The modulated optical signal is as follows: Figure 4 For the sake of distinction, this phase modulation is called the first modulation.

[0051] like Figure 4As shown, the optical signal after the first modulation enters the dual-bandpass optical filter 1022, and is filtered by the dual-bandpass optical filter 1022 to filter out the optical sideband pair of the required order. The order of the optical sideband pair is n, and the center frequency of the optical signal filtered by the dual-bandpass optical filter 1022 is f 0 ±nf 1 , bandwidth is nB 1 It should be noted that the specific order to be filtered out, i.e., the value of n, can be determined according to the needs of the actual application scenario, and this embodiment does not limit this. The dual-bandpass optical filter 1022 of the corresponding working frequency band is selected according to the required order of the optical sideband pair. In some examples, n can be an order with a relatively high signal-to-noise ratio in the optical signal obtained by the first modulation. For example, a signal-to-noise ratio threshold can be predetermined, and a first-order optical sideband pair can be selected from the optical sideband pairs that are higher than the signal-to-noise ratio threshold.

[0052] The optical signal filtered out by the dual-bandpass optical filter 1022 enters the second phase modulator 1024. The second phase modulator 1024 performs phase modulation on the optical signal through the second modulation signal. The modulated optical signal is as follows: Figure 5 For the sake of distinction, this phase modulation is called the second modulation.

[0053] like Figure 5 As shown, the bandpass optical filter 1025 performs filtering processing on the optical signal obtained after the second modulation, and filters out the above-mentioned p pairs of optical signals with a bandwidth of nB. 1 For example, p pairs of optical sidebands include: the mth to m+p-1th order optical sidebands generated after the second modulation, and the center frequencies are respectively expressed as: f 0 +nf 1 -(m+p-1)f 2 , ..., f 0 +nf 1 -(m+1)f 2 , f 0 -nf 1 +(m+1)f 2 , ..., f 0 -nf 1 +(m+p-1)f 2 .

[0054] For example, Figure 5 The center frequency is f 0 +nf 1 -mf 2 The optical sideband is the center frequency f 0 +nf 1 The mth-order optical sideband is formed by modulating the optical sideband of 0-nf 1 +mf 2 The optical sideband is the center frequency f 0 -nf 1 The m-th order optical sideband is formed by modulating the optical sideband of the original carrier frequency f. These two optical sidebands constitute the m-th order optical sideband pair. In this paper, the m-th order optical sideband pair refers to the optical sideband closest to the original carrier frequency f. 0 It should be noted that, depending on the values ​​of various parameters, f 0 +nf 1 -mf 2 、f 0 -nf 1 +mf 2 May be less than the original carrier frequency f 0 , or, it may be greater than the original carrier frequency f 0 . And when f 0 +nf 1 -mf 2 Greater than the original carrier frequency f 0 When f 0 -nf 1 +mf 2 Less than the original carrier frequency f 0 , on the contrary, when f 0 +nf 1 -mf 2 Less than the original carrier frequency f 0 When f 0 -nf 1 +mf 2 Greater than the original carrier frequency f 0 .

[0055] The center frequency is f 0 +nf 1 -(m+1)f 2 The optical sideband is the center frequency f 0 +nf 1 The m+1th order optical sideband is formed by modulating the optical sideband of 0 -nf 1 +(m+1)f 2 The optical sideband is the center frequency f 0 -nf 1 The m+1th order optical sideband is formed by modulating the optical sideband, and these two optical sidebands constitute the m+1th order optical sideband pair.

[0056] In some examples, the bandwidth required to filter out p pairs more accurately is nB 1 The optical sideband pair, the bandwidth B of the bandpass optical filter 1025 f The following conditions need to be met:

[0057] 2(p-1)f 2 -2(nf 1 -mf 2 )+nB 1 <B f <2pf 2 -2(nf 1 -mf 2 )-nB 1 .

[0058] For example, if two pairs of optical sidebands are filtered out (p=2), the bandwidth B of the bandpass optical filter 1025 is f Need to meet:

[0059] 2f 2 -2(nf 1 -mf 2 )+nB 1 <B f <4f 2 -2(nf 1 -mf 2 )-nB 1

[0060] At this time, the two pairs of optical sidebands filtered out are the mth order and m+1th order optical sidebands generated after the second phase modulation, which are respectively 0 The center frequencies of the two pairs of optical sidebands filtered out are: 0 +nf 1 -(m+1)f 2 , and f 0 -nf 1 +(m+1)f 2 , and the bandwidth of each optical sideband is nB 1 .

[0061] For another example, if three pairs of optical sidebands are filtered out (p=3), the bandwidth B of the bandpass optical filter 1025 is f Need to meet:

[0062] 4f 2 -2(nf 1 -mf 2 )+nB 1 <B f <6f 2 -2(nf 1 -mf 2 )-nB 1

[0063] At this time, the three pairs of optical sidebands filtered out are the mth order, m+1th order, and m+2th order optical sidebands generated after the second phase modulation. The center frequencies of the three pairs of optical sidebands filtered out are: f 0 +nf 1 -(m+2)f 2 , f 0 +nf 1 -(m+1)f 2 , f 0 -nf 1 +(m+1)f 2 and f 0 -nf 1 +(m+2)f 2 , and the bandwidth of each optical sideband is nB 1 .

[0064] It should be noted that the specific number of optical sideband pairs that need to be filtered out can be determined according to the needs of the actual application scenario, so as to configure the bandpass optical filter 1025 of the corresponding bandwidth. By increasing the number of pairs of optical sidebands filtered out, broadband radar transmission signals of more frequency bands can be generated simultaneously, which is conducive to further enriching the functions of the radar system.

[0065] Furthermore, in order to ensure signal strength, the optical frequency conversion module 102 further includes: a first optical amplifier 1023 and a second optical amplifier 1026. The first optical amplifier 1023 is connected between the dual-bandpass optical filter 1022 and the second phase modulator 1024, and is used to amplify the optical signal filtered by the dual-bandpass optical filter 1022. Specifically, the dual-bandpass optical filter 1022 is connected to the first optical amplifier 1023 by means of an optical waveguide connection, and the first optical amplifier 1023 is connected to the second phase modulator 1024 by means of an optical waveguide connection.

[0066] The second optical amplifier 1026 is connected between the bandpass optical filter 1025 and the first optical coupler 103, and is used to amplify the optical signal filtered by the bandpass optical filter 1025. Specifically, the bandpass optical filter 1025 is connected to the second optical amplifier 1026 by an optical waveguide connection, and the optical signal amplified by the second optical amplifier 1026 enters the first optical coupler 103.

[0067] For example, both the first optical amplifier 1023 and the second optical amplifier 1026 may be erbium-doped fiber amplifiers. Of course, other optical amplifiers may also be used, and this embodiment does not limit this.

[0068] The first optical coupler 103 plays a beam splitting role, and is used to split the optical signal output by the optical frequency conversion module 102, for example, the optical signal amplified by the second optical amplifier 1026, into two paths, one of which is input into the first photodetector 104, and the other is output as a reference optical signal to the radar receiving device 20.

[0069] The first photodetector 104 is connected to one of the output ends of the first optical coupler 103 by means of an optical waveguide, and is used to convert p to nB. 1 The optical sideband pair is converted into a radio frequency signal, the radio frequency signal includes: 2p-1 bandwidth is 2nB 1 Specifically, the first photodetector 104 converts the p pairs of optical sidebands into radio frequency signals using the beat frequency principle to obtain 3p-2 different characteristic frequency bands, where the bandwidth is 2nB. 1 There are 2p-1 characteristic frequency bands, and the center frequencies are: f 2 -2(nf 1 -mf 2 ),2|nf 1 -mf 2 |, 2f 2 -2(nf 1 -mf 2 ), ..., (2p-2)f 2 -2(nf 1 -mf 2 ); there are p-1 signals with bandwidth 0, and their center frequencies are: f 2 ,2f 2 ,……,(p-1)f 2 .

[0070] For example, Figure 6 As shown, if p=2, the input optical signal includes two pairs of optical sidebands, namely the mth order and m+1th order optical sidebands. After the first photodetector 104 beats the signal, four different frequency bands are generated, and the center frequencies are f 2 -2(nf 1 -mf 2 ), 2|nf 1 -mf 2 |, f 2 , 2f 2 -2(nf 1 -mf 2 ), the bandwidth is 2nB 1 ,2nB 1 ,0,2nB 1 Therefore, there are three characteristic frequency bands, and the center frequencies of the three characteristic frequency bands are: 2 -2(nf 1 -mf2 ), 2|nf 1 -mf 2 |, 2f 2 -2(nf 1 -mf 2 ).

[0071] Similarly, if p=3, that is, the input optical signal includes three pairs of optical sideband pairs, namely the mth order, m+1th order and m+2th order optical sideband pairs, after the first photodetector 104 beats, 7 different frequency bands will be obtained, among which the bandwidth is 2nB 1 There are five characteristic frequency bands, namely, f 2 -2(nf 1 -mf 2 ),2|nf 1 -mf 2 |,2f 2 -2(nf 1 -mf 2 ),3f 2 -2(nf 1 -mf 2 ), 4f 2 -2(nf 1 -mf 2 ) There are two frequency bands with bandwidth of 0, namely f 2 and 2f 2 .

[0072] Bandwidth is 2nB 1 The characteristic frequency band is also the alternative signal frequency band of the radar transmission. It can also be seen that the center frequency of the generated broadband radar transmission signal is the same as the center frequency f of the first modulation signal mentioned above. 1 , the center frequency f of the second modulation signal 2 The bandwidth of the generated broadband radar transmission signal is related to the bandwidth B of the first modulation signal. 1 Related to the order n of the optical sideband pair selected using the dual-bandpass optical filter 1022.

[0073] Therefore, the center frequency f of the first modulated signal output by the first microwave signal source 12 can be determined according to the center frequency and bandwidth of the required radar transmission signal. 1 , the center frequency f of the second microwave signal source 13 2 , the order n of the optical sideband pair selected by the dual-bandpass optical filter 1022 and the bandwidth of the bandpass optical filter 1025. By adjusting the bandwidth of the first modulated signal output by the first microwave signal source 12 and the order n of the optical sideband pair selected by the dual-bandpass optical filter 1022, the bandwidth of the radar transmission signal can be tunable.

[0074] Furthermore, the bandpass electric filter 105 is connected to the first photodetector 104 by means of a radio frequency waveguide connection. The radio frequency signal output by the first photodetector 104 enters the bandpass electric filter 105, and the bandpass electric filter 105 filters out radio frequency signals of M different frequency bands from the above 2p-1 characteristic frequency bands, and outputs the radio frequency signals of each frequency band from independent channels to be transmitted to the transmitting antenna 11 of the corresponding frequency band for transmission. Wherein, M is an integer greater than or equal to 2.

[0075] That is to say, the above-mentioned bandpass electric filter 105 is a multi-channel bandpass electric filter 105. The specific number of channels can be determined according to the number of frequency bands required for the radar transmission signal, and the working band of each channel corresponds to a characteristic frequency band that needs to be filtered out. Taking p=2, the number of characteristic frequency bands is 3, and M=2 as an example, a dual-channel bandpass electric filter 105 can be used at this time. For example, the two frequency bands with the highest and second highest signal-to-noise ratios can be selected from these three characteristic frequency bands to realize the transmission signal of the microwave photon dual-band radar. It should be noted that Figure 6 The height of the signal shown in does not represent the size of the signal-to-noise ratio, and is selected specifically according to the signal-to-noise ratio of each characteristic frequency band. For example, the center frequencies of the required dual-band radar transmission signals are 9 GHz and 13 GHz, respectively, so the operating frequency band of one channel of the dual-channel bandpass electric filter 105 can be 8-10 GHz, and the operating frequency band of the other channel can be 12-14 GHz.

[0076] In some examples, in order to ensure that the radar transmission signal has sufficient power, the radar transmitting device 10 provided in this embodiment also includes: a power amplifier 106. The input end of the power amplifier 106 is connected to the output end of the above-mentioned bandpass electric filter 105 through a radio frequency waveguide connection method, and the output end of the power amplifier 106 is used to connect to the transmitting antenna 11 corresponding to each frequency band through a radio frequency waveguide connection method. At this time, the radio frequency signals of each frequency band output by the bandpass electric filter 105 are sent to the power amplifier 106, which is amplified by the power amplifier 106 and then transmitted to the corresponding transmitting antenna 11 for transmission. It should be noted that Figure 1 The number of transmitting antennas 11 shown in the figure is for illustration only and is not intended to be limiting, and can be set according to actual needs.

[0077] The radar transmitting device 10 provided in the embodiment of the present invention can obtain broadband radar transmission signals of multiple frequency bands at the same time based on the filtered optical sideband pairs by reasonably setting the bandwidth of the bandpass optical filter 1025. For example, by setting the bandpass optical filter 1025 to filter out two pairs of optical sideband pairs, broadband radar transmission signals of two frequency bands can be obtained at the same time, which is beneficial to improve the problems of large size, complex structure and difficult maintenance of the radar while enriching the radar function.

[0078] Moreover, compared to a method of generating radar transmission signals of different frequencies by switching parameters (this method can only generate a radar transmission signal of one frequency band at the same time, and the transmission signals of different frequency bands generated at different times are not completely coherent), in the radar transmitting device 10 provided in an embodiment of the present invention, radar transmission signals of multiple frequency bands generated simultaneously are derived from the same optical signal, and radar transmission signals of different frequency bands can be completely coherent, thereby improving the detection distance and positioning accuracy of the radar system.

[0079] In addition, unlike the method of using the optical frequency comb output by the mode-locked laser 101 to provide a reconfigurable waveform for the radar transmission signal and provide an ultra-low jitter narrow pulse for the optical analog-to-digital conversion of the receiver, this method is limited by the interval of the optical frequency comb and cannot generate a large bandwidth signal. Its bandwidth is only in the order of hundreds of megahertz, and it is impossible to achieve higher precision detection. The technical solution provided by the embodiment of the present invention can effectively increase the bandwidth of the radar transmission signal through the frequency doubling technology, which is conducive to achieving higher precision detection. For example, the bandwidth can reach the order of GHz, and the radar distance resolution can reach the order of centimeters. It can be understood that the radar distance resolution refers to the minimum distinguishable distance between two adjacent point targets in the same direction. The larger the bandwidth of the radar transmission signal, the better the radar distance resolution.

[0080] In a second aspect, an embodiment of the present invention further provides a microwave photon multi-band radar system, such as Figure 7 As shown, the system includes: M transmitting antennas 11, M receiving antennas 21, a radar receiving device 20, and the radar transmitting device 10 provided in the first aspect above. It should be noted that, Figure 7 The number of antenna pairs shown in the figure is for illustration only and is not intended to be limiting. It should be set according to actual needs.

[0081] The radar transmitting device 10 is connected to the M transmitting antennas 11 respectively, and the frequency bands of the M radio frequency signals output by the radar transmitting device 10 correspond one-to-one to the transmitting frequency bands of the M transmitting antennas 11. The radar receiving device 20 is connected to the M receiving antennas 21 respectively, and the receiving frequency bands of the M receiving antennas 21 correspond one-to-one to the transmitting frequency bands of the M transmitting antennas 11.

[0082] For example, when the radar transmitting device 10 generates radar transmitting signals of two frequency bands, M is equal to 2. At this time, two groups of antennas need to be configured, one group including a transmitting antenna 11 and a receiving antenna 21.

[0083] The radar receiving device 20 is adapted to the radar transmitting device 10, and is used to process the target echo signals received by the M receiving antennas 21 to obtain the detected target information. In some examples, the radar receiving device 20 may adopt a de-slanted receiving module based on microwave photon technology, or may adopt other applicable receiving modules, which is not limited in this embodiment.

[0084] Specifically, the above-mentioned de-skewed receiving module includes: an optical delay line 201, an electrical coupler 202, a first low noise amplifier 203, a Mach-Zehnder modulator 204, a bias point controller 205, a second optical coupler 206, a second photodetector 207, an intermediate frequency filter 208 and a signal processor 209.

[0085] The optical delay line 201 is connected to the Mach-Zehnder modulator 204 and the first optical coupler 103 in the radar transmitting device 10 respectively by means of an optical waveguide connection. The Mach-Zehnder modulator 204 is connected to the output end of the bias point controller 205 and the output end of the first low noise amplifier 203 respectively by means of a radio frequency waveguide connection, and is connected to the input end of the second optical coupler 206 by means of an optical waveguide connection. The input end of the first low noise amplifier 203 is connected to the output end of the electric coupler 202 by means of a radio frequency waveguide connection. Each input end of the electric coupler 202 is connected to the M receiving antennas 21 in a one-to-one correspondence by means of a radio frequency waveguide connection. The first output end of the second optical coupler 206 is connected to the signal processor 209 in sequence via the second photodetector 207 and the intermediate frequency filter 208. The first output end of the second optical coupler 206 is connected to the second photodetector 207 through an optical waveguide connection, the second photodetector 207 is connected to the intermediate frequency filter 208 through a radio frequency waveguide connection, and the output interface of the intermediate frequency filter 208 is connected to the signal processor 209 through a radio frequency waveguide connection. The second output end of the second optical coupler 206 is connected to the input end of the bias point controller 205 through an optical waveguide connection.

[0086] In specific use, the target echo signals of the target object are received by M receiving antennas 21 respectively, and the M target echo signals enter the first low noise amplifier 203 after being coupled by the electrical coupler 202, and the amplified signal is used as the modulation signal of the Mach-Zehnder modulator 204.

[0087] One of the optical signals outputted by the first optical coupler 103 in the radar transmitting device 10 is delayed by the optical delay line 201 and then injected into the Mach-Zehnder modulator 204 as a reference optical signal.

[0088] The reference optical signal modulated by the Mach-Zehnder modulator 204 is divided into two paths through the second optical coupler 206, wherein the first optical signal is input into the second photodetector 207, and the second optical signal enters the bias point controller 205, so that the bias point controller 205 provides a bias voltage for the Mach-Zehnder modulator 204 according to the second optical signal, so that the Mach-Zehnder modulator 204 works in an orthogonal state.

[0089] The second photodetector 207 beats the optical signal modulated by the Mach-Zehnder modulator 204 to obtain an intermediate frequency electrical signal carrying target information. The intermediate frequency electrical signal is filtered by the intermediate frequency filter 208 and enters the signal processor 209. The signal processor 209 is an analog-to-digital converter and a digital signal processor, which is used to process the received intermediate frequency electrical signal and extract the target information therefrom. The specific process can refer to the relevant technology and will not be described in detail here.

[0090] In some examples, the de-skewing receiving module may further include: a second low noise amplifier (not shown) disposed between the intermediate frequency filter 208 and the second photodetector 207. The second low noise amplifier may be connected to the second photodetector 207 and the intermediate frequency filter 208 respectively by means of a radio frequency waveguide connection, so that the intermediate frequency electrical signal output by the second photodetector 207 is amplified by the second low noise amplifier and then enters the intermediate frequency filter 208 for filtering, so as to improve the signal strength and facilitate the extraction of target information.

[0091] In addition, in order to verify the effect of the technical solution of the present invention, the inventor also conducted an experimental verification using a dual-band as an example. In the experiment, the first microwave signal source 12 generates a center frequency f 1 The second microwave signal source 13 generates a linear frequency modulation signal with a center frequency of 17.85 GHz, a bandwidth of 300 MHz, and a period of 50 μs. 2 The signal is 27.1429 GHz. If n is 5 and m is 3, the first photodetector 104 beats the frequency to obtain signals with center frequencies of 11.5003 GHz, 15.6426 GHz, 27.1429 GHz, and 38.6432 GHz, and the bandwidths are 3 GHz, 3 GHz, 0, and 3 GHz, respectively. The linear frequency modulation signals of 11.5003 GHz (X band) and 15.6426 GHz (Ku band) are filtered out by the bandpass filter 105 as radar transmission signals, such as Figure 8 It should be noted that the frequency ranges of the internationally specified frequency bands are: X-band: 8-12 GHz, Ku-band: 12-18 GHz.

[0092] In the experiment, the detection target is a pair of corner reflectors 70 cm away from the two transmitting antennas 11, and the distance between the two corner reflectors is set to 5.5 cm. The normalized power spectrum of the intermediate frequency signal obtained after the received target echo signal is de-slanted is as follows: Fig. 9 As shown, Fig. 9The frequencies corresponding to the two peaks differ by 0.024MHz, which means that the distance between the two corner reflectors is 5.99cm. It should be noted that the distance between the corner reflectors measured here (5.99cm) is slightly larger than the actual distance (5.5cm), which may be due to the inconsistency between the center of electromagnetic wave scattering and the center of mass of the corner reflectors.

[0093] It should also be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0094] In addition, the functional modules in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0095] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A microwave photon multi-band radar transmitting device, characterized in that: include: A laser, used for outputting a continuous optical signal as an original carrier; An optical frequency conversion module, used for performing phase modulation and filtering on the original carrier to obtain p pairs of optical sideband pairs with a bandwidth of nB1, wherein p is an integer greater than or equal to 2, nB1 is greater than zero, the optical sideband whose frequency is closest to the original carrier frequency after the phase modulation is the m-th order optical sideband, and the p pairs of optical sideband pairs include: the m-th order to the m+p-1-th order optical sidebands generated after the phase modulation; A first optical coupler, used to divide the optical signal output by the optical frequency conversion module into two paths, one path is input into the first photodetector, and the other path is output as a reference optical signal to the radar receiving device; The first photodetector is used to convert the p pairs of optical sidebands with a bandwidth of nB1 into radio frequency signals, wherein the radio frequency signals include: 2p-1 characteristic frequency bands with a bandwidth of 2nB1; and A bandpass electric filter, used to filter out radio frequency signals of M different frequency bands from the 2p-1 characteristic frequency bands, and output the radio frequency signals of each frequency band from independent channels to transmit them to the transmitting antenna of the corresponding frequency band, wherein M is an integer greater than or equal to 2; Wherein, the optical frequency conversion module comprises: A first phase modulator is connected to the laser and is used to modulate the original carrier output by the laser through a first modulation signal input by a first microwave signal source of an external device, wherein the bandwidth of the first modulation signal is B1; A dual-bandpass optical filter connected to the output end of the first phase modulator, used for filtering the optical signal after the first modulation to filter out the n-th order optical sideband pair therein; A second phase modulator is connected to the output end of the dual-bandpass optical filter and is used to phase modulate the optical signal filtered out by the dual-bandpass optical filter through a second modulation signal input by an external second microwave signal source; A bandpass optical filter is connected to the output end of the second phase modulator and is used to filter the optical signal obtained after the second modulation to filter out the p pairs of optical sidebands with a bandwidth of nB1.

2. The device according to claim 1, characterized in that The optical frequency conversion module also includes: a first optical amplifier, connected between the dual-bandpass optical filter and the second phase modulator, and configured to amplify the optical signal filtered out by the dual-bandpass optical filter; The second optical amplifier is connected between the bandpass optical filter and the first optical coupler, and is used to amplify the optical signal filtered out by the bandpass optical filter.

3. The device according to claim 1, characterized in that The bandwidth of the bandpass optical filter satisfies the following conditions: 2(p-1)f2-2(nf1-mf2)+nB1<B f <2pf2-2(nf1-mf2)-nB1 Among them, B f represents the bandwidth of the bandpass optical filter, f1 is the center frequency of the first modulation signal, and f2 is the center frequency of the second modulation signal.

4. The device according to claim 3, characterized in that p is equal to 2, and there are three characteristic frequency bands, and the center frequencies of the three characteristic frequency bands are: f2-2(nf1-mf2), 2|nf1-mf2|, 2f2-2(nf1-mf2).

5. The device according to claim 1, characterized in that Also includes: A power amplifier, the input end of the power amplifier is connected to the output end of the bandpass electric filter, and is used to power amplify the radio frequency signals of each frequency band output by the bandpass electric filter, and the output end of the power amplifier is used to connect to the transmitting antenna of the corresponding frequency band.

6. A microwave photon multi-band radar system, characterized in that: include: M transmitting antennas, M receiving antennas, a radar receiving device, and the radar transmitting device according to any one of claims 1 to 5; The radar transmitting device is connected to the M transmitting antennas respectively, and the frequency bands of the M radio frequency signals output by the radar transmitting device correspond one-to-one to the transmitting frequency bands of the M transmitting antennas; The radar receiving device is connected to the M receiving antennas respectively, and the receiving frequency bands of the M receiving antennas correspond one-to-one to the transmitting frequency bands of the M transmitting antennas.

7. The system according to claim 6, characterized in that M is equal to 2.

8. The system according to claim 6, characterized in that The radar receiving device comprises: an optical delay line, an electrical coupler, a first low noise amplifier, a Mach-Zehnder modulator, a bias point controller, a second optical coupler, a second photodetector, an intermediate frequency filter and a signal processor for extracting target information from a received signal. The optical delay line is respectively connected to the Mach-Zehnder modulator and the first optical coupler in the radar transmitting device; The Mach-Zehnder modulator is also respectively connected to the output end of the bias point controller, the input end of the second optical coupler and the output end of the first low-noise amplifier, the input end of the first low-noise amplifier is connected to the output end of the electrical coupler, the input end of the electrical coupler is connected to the M receiving antennas, the first output end of the second optical coupler is connected to the signal processor via the second photodetector and the intermediate frequency filter in sequence, and the second output end of the second optical coupler is connected to the input end of the bias point controller.

9. The system according to claim 8, characterized in that The radar receiving device further includes: a second low noise amplifier, an input end of the second low noise amplifier is connected to the second photodetector, and an output end of the second low noise amplifier is connected to the intermediate frequency filter.

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