Analog signal conditioning circuit and radar signal simulator system

Abstract

The application provides a kind of analog signal conditioning circuit and radar signal simulator system, wherein the analog signal conditioning circuit includes signal receiving unit, for receiving target signal;Down conversion unit, for by down conversion mixer, target signal is down converted from first frequency range to second frequency range;Analog transmission unit, for the target signal through radio frequency cable is divided into two target sub signals;Up conversion unit, for by up conversion mixer, target sub signal after adjusting signal intensity is up converted to first frequency range;Signal transmitting unit, for two target sub signals are combined into one mixed signal;Wherein the input frequency of the local oscillator signal of down conversion mixer and each up conversion mixer is derived from the output frequency of the corresponding set phase-locked loop, and the reference frequency of several phase-locked loops is derived from the same reference source, so that different echo intensity and different distance of micro-motion target are simulated, and the reliability of radar detection is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radar signal simulation, and particularly relates to a simulation signal conditioning circuit and a radar signal simulator system. BACKGROUND

[0002] With the rapid development of science and technology, radar microwave technology is increasingly widely used in the field of sensors. Millimeter wave radar is a kind of sensor capable of measuring speed and distance. Specifically, it can emit electromagnetic waves, receive the electromagnetic wave signals reflected back after encountering a target, and analyze the echo signals to detect the distance and speed of the target. It is widely used in military, medical, industrial and other technical fields.

[0003] The breathing and heartbeat of the human body can cause slight movements of the chest and other parts. The chest will rise and fall regularly during breathing, and the heartbeat will also produce weak but continuous vibrations. The breathing and heartbeat of the human body can be monitored by radar devices such as millimeter wave radar, which have high frequency and accuracy, so as to remotely and non-contactly monitor the vital signs of patients. In related technologies, the simulation and testing of radar are usually realized by a mechanical method. Specifically, the electromagnetic wave signals emitted by the radar are reflected back to the original path by a metal corner reflector driven by a motor, and the movement of the metal corner reflector is used to simulate the moving target to be detected. However, the main disadvantage of this method is that mechanical vibration will cause wear and aging. Long-term use will reduce the accuracy and service life of the system. As the accuracy of the system decreases, regular calibration and maintenance are required, which increases the cost and complexity of use.

[0004] Furthermore, the radar target simulator of the above-mentioned mechanical vibration method has a fixed structure size of the metal corner reflector. The signal strength of the radar echo is fixed and unchanged during testing. Different distances and different sizes of scattering cross-sections of the simulated target will produce different intensity of echo signals. For example, the radar scattering cross-sections of infants, children, adults and patients are different, and the echo intensity is different. Therefore, the traditional mechanical vibration simulation of the micro-motion target will make the radar target simulator unable to simulate radar echoes of different intensities, resulting in limited reliability and use scenarios of the radar. SUMMARY

[0005] The application provides a simulation signal conditioning circuit and a radar signal simulator system, which can simulate micro-motion targets of different echo intensities and different distances according to requirements, and improve the accuracy and reliability of radar detection of micro-motion targets.

[0006] To solve the above technical problems, the application provides a simulation signal conditioning circuit, which comprises:

[0007] A signal receiving unit is configured to receive a target signal.

[0008] a down-conversion unit, configured to down-convert the target signal from a first frequency range to a second frequency range by a down-conversion mixer;

[0009] an analog transmission unit, configured to pass the target signal down-converted to the second frequency range through a radio frequency cable with a preset length, and divide the target signal passed through the radio frequency cable into at least two target sub-signals;

[0010] an up-conversion unit, comprising at least two up-conversion branches, each of the up-conversion branches is provided with a digital control attenuator for adjusting the signal intensity of the target sub-signals, and an up-conversion mixer for up-converting the target sub-signals with adjusted signal intensity to the first frequency range;

[0011] a signal transmission unit, configured to combine the at least two target sub-signals up-converted to the first frequency range into one mixed signal, and transmit the mixed signal to a radar to be tested;

[0012] wherein the input frequency of the local oscillator signal of the down-conversion mixer and each of the up-conversion mixers is derived from the output frequency of a corresponding phase-locked loop, and the reference frequency of a plurality of the phase-locked loops is derived from a same reference source.

[0013] As a further improvement of the present application, the phase-locked loops comprise at least a first phase-locked loop connected with the down-conversion mixer, and a second phase-locked loop and a third phase-locked loop connected with a plurality of the up-conversion mixers;

[0014] The reference source is a reference crystal oscillator, and the first phase-locked loop, the second phase-locked loop and the third phase-locked loop are connected with the reference crystal oscillator.

[0015] As a further improvement of the present application, the down-conversion unit further comprises a low-noise amplifier connected with the signal receiving unit, a first input end of the down-conversion mixer is connected with the low-noise amplifier, and a second input end of the down-conversion mixer is connected with the first phase-locked loop;

[0016] The low-noise amplifier is configured to amplify the target signal, and transmit the amplified target signal to the down-conversion mixer, so that the down-conversion mixer down-converts the target signal from a first frequency range to a second frequency range.

[0017] As a further improvement of the present application, the down-conversion unit further comprises a filter connected with an output end of the down-conversion mixer, and a first amplifier connected with the filter;

[0018] The filter is configured to filter the target signal down-converted to the second frequency range, and the first amplifier is configured to amplify the filtered target signal and transmit the amplified target signal to the analog transmission unit.

[0019] As a further improvement of the present application, the analog transmission unit comprises at least one radio frequency cable and a power divider connected to the radio frequency cable.

[0020] The radio frequency cable is connected to the down-conversion unit and configured to simulate a target distance of a preset length, and the power divider is configured to divide the target signal passing through the radio frequency cable into at least a first target sub-signal and a second target sub-signal with equal power.

[0021] As a further improvement of the present application, the up-conversion branch comprises at least a first up-conversion branch configured to transmit the first target sub-signal and a second up-conversion branch configured to transmit the second target sub-signal.

[0022] The first up-conversion branch is provided with a first digital attenuator configured to adjust the signal intensity of the first target sub-signal, and a first up-conversion mixer configured to up-convert the first target sub-signal with adjusted signal intensity to the first frequency range.

[0023] The second up-conversion branch is provided with a second digital attenuator configured to adjust the signal intensity of the second target sub-signal, and a second up-conversion mixer configured to up-convert the second target sub-signal with adjusted signal intensity to the first frequency range.

[0024] As a further improvement of the present application, a first input end of the first up-conversion mixer is connected to the first digital attenuator, and a second input end of the first up-conversion mixer is connected to the second phase-locked loop.

[0025] A first input end of the second up-conversion mixer is connected to the second digital attenuator, and a second input end of the second up-conversion mixer is connected to the third phase-locked loop. The output ends of the first up-conversion mixer and the second up-conversion mixer are connected to the signal transmission unit.

[0026] As a further improvement of the present application, the first up-conversion branch is further provided with a second amplifier connected to the first digital attenuator and the power divider, and the second up-conversion branch is further provided with a third amplifier connected to the second digital attenuator and the power divider.

[0027] As a further improvement of the present application, the signal transmission unit comprises a combiner connected to a plurality of up-conversion branches, and a transmitting antenna connected to the combiner.

[0028] The combiner is used to combine at least two target sub-signals up-converted to the first frequency range into one mixed signal, and the transmitting antenna is used to transmit the mixed signal to the radar to be tested.

[0029] As a further improvement of the present application, a band-pass filter is further arranged between the combiner and the transmitting antenna, and the band-pass filter is used to filter out the spurious signals in the mixed signal, so that the transmitting antenna transmits the filtered mixed signal to the radar to be tested.

[0030] As a further improvement of the present application, the present application further provides a radar signal simulator system, which comprises:

[0031] The host computer is in bidirectional communication connection with the microcontroller, the input and output device in bidirectional communication connection with the microcontroller, and the analog signal conditioning circuit.

[0032] Compared with the prior art, the analog signal conditioning circuit and the radar signal simulator system provided by the present application can make the Doppler frequencies of the first up-conversion branch and the second up-conversion branch close to 0 Hz, because the reference sources of the down-conversion mixer, the first up-conversion mixer and the second up-conversion mixer are all the same active crystal oscillator. By adjusting the input frequencies of the local oscillator signals of the down-conversion mixer, the first up-conversion mixer and the second up-conversion mixer, the Doppler frequencies of the first up-conversion branch and the second up-conversion branch can be adjusted, so as to independently control the frequency changes of the respective up-conversion branches, realize the microsecond-level frequency switching time, and realize the frequency switching range of 0.01 Hz to several hundred kHz.

[0033] The first up-conversion branch and the second up-conversion branch are correspondingly provided with the first digital attenuator and the second digital attenuator, which can control the echo intensity of the respective up-conversion branches, that is, the size of the radar scattering cross section. By changing the length of the external radio frequency cable, micro-motion targets at different distances can be simulated, without the need to move the radar target simulator or the position of the radar to be tested. Only the radio frequency cable with the corresponding length needs to be replaced according to the simulated distance, which is simple and convenient. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0035] Figure 1 The functional module diagram of the analog signal conditioning circuit provided by the embodiment of the present application.

[0036] Figure 2 The structure schematic diagram of each unit in the analog signal conditioning circuit provided by the embodiment of the present application.

[0037] Figure 3 The structure schematic diagram of the analog signal conditioning circuit provided by the embodiment of the present application.

[0038] Figure 4 The structure schematic diagram of the reference crystal oscillator in the analog signal conditioning circuit provided by the embodiment of the present application.

[0039] Figure 5 The structure schematic diagram of the analog signal conditioning circuit provided by the embodiment of the present application with a micro-motion target added.

[0040] Figure 6 The structure schematic diagram of the frequency multiplier in the analog signal conditioning circuit provided by the embodiment of the present application.

[0041] Figure 7 The structure schematic diagram of the radar signal simulator system provided by the embodiment of the present application.

[0042] Explanation of reference signs:

[0043] 1-analog signal conditioning circuit; 2-host computer; 3-microcontroller; 4-input and output device;

[0044] 10-signal receiving unit; 11-receiving antenna;

[0045] 20-down-conversion unit; 21-low-noise amplifier; 22-down-conversion mixer; 23-filter; 24-first amplifier;

[0046] 30-analog transmission unit; 31-radio frequency cable; 32-power divider;

[0047] 40-up-conversion unit; 41-first up-conversion branch; 42-second amplifier; 43-first digital control attenuator; 44-first up-conversion mixer; 45-second up-conversion branch; 46-third amplifier; 47-second digital control attenuator; 48-second up-conversion mixer;

[0048] 50-signal transmitting unit; 51-combiner; 52-band-pass filter; 53-transmitting antenna;

[0049] 60-reference source; 61-first phase-locked loop; 62-second phase-locked loop; 63-third phase-locked loop. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the embodiments of the present application are further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present application, and are not used to limit the embodiments of the present application.

[0051] In the description of the embodiments of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0052] In order to make the description of the present disclosure more detailed and complete, the following describes the embodiments of the present application with respect to the embodiments and specific embodiments of the present application; but this is not the only form of implementation or use of the specific embodiments of the present application. The embodiments include the features of the specific embodiments and the method steps and their order used to construct and operate the specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences.

[0053] With the rapid development of science and technology, radar microwave technology is increasingly widely used in the field of sensors. Millimeter wave radar is a sensor that can measure speed and distance. Specifically, it can emit electromagnetic waves, receive the reflected electromagnetic wave signals after encountering targets, and analyze the echo signals to detect the distance, speed, etc. of the targets. It is widely used in military, medical, industrial, etc. technical fields.

[0054] The breathing and heartbeat of the human body can cause slight movements of the chest and other parts. The chest will regularly fluctuate when breathing, and the heartbeat will also produce weak but continuous vibrations. The breathing and heartbeat of the human body can be monitored by radar devices such as millimeter wave radar with high frequency and accuracy, so as to remotely and non-contactly monitor the vital signs of the patient. In addition, during sleep, accurate monitoring of breathing and heartbeat can help analyze sleep quality and diagnose sleep-related diseases such as sleep apnea syndrome.

[0055] In practical applications, when the radar waves emitted by millimeter-level radar illuminate the human body, they will generate the Doppler effect when interacting with moving targets. The speed changes of human breathing and heartbeat will cause corresponding frequency shifts in the reflected radar waves. By detecting the regular changes in this frequency shift, the frequency characteristics corresponding to breathing and heartbeat can be distinguished. By monitoring and simulating them, the required breathing and heartbeat-related information can be extracted.

[0056] This millimeter-scale radar, capable of detecting minute movements such as breathing and heartbeat, needs to be developed and mass-produced using a radar target simulator to simulate and test targets of different distances and sizes with different RCS (Radar Cross Section).

[0057] In related technologies, radar simulation and testing are usually achieved through mechanical means. Specifically, a motor drives a metal corner reflector to reflect the electromagnetic wave signal emitted by the radar back along its original path. The movement of the metal corner reflector is used to simulate the moving target to be detected. However, the main drawback of this method is that mechanical vibration will cause wear and aging. Long-term use will reduce the accuracy and lifespan of the system. As the accuracy of the system decreases, regular calibration and maintenance are required, which increases the cost and complexity of use.

[0058] Furthermore, in radar target simulators using the aforementioned mechanical vibration method, the structural dimensions of the metal corner reflector are fixed, resulting in a constant signal strength of the radar echo during testing. Simulated targets at different distances and with different scattering cross-sections will produce echo signals of varying intensities. For example, infants, children, adults, and patients produce different radar scattering cross-sections and echo intensities. Therefore, the traditional method of simulating micro-moving targets using mechanical vibration makes it impossible for radar target simulators to simulate radar echoes of varying intensities, thus limiting the reliability of radar detection and making it unsuitable for a wider range of applications.

[0059] In view of this, please refer to Figures 1-7 This application provides an analog signal conditioning circuit and a radar signal simulator system, which can simulate micro-moving targets with different echo intensities and distances according to requirements, thereby improving the accuracy and reliability of radar detection of micro-moving targets.

[0060] It is understood that in the embodiments of this application, "or" describes the relationship between related objects, indicating that there can be two relationships. For example, A or B can mean: A exists alone, or B exists alone, where A and B can be singular or plural.

[0061] The term "connection" in the present application describes the connection relationship between two objects, which can represent two connection relationships, for example, A and B are connected, which can represent two cases that A is directly connected with B and A is connected with B through C.

[0062] In the embodiments of the present application, "exemplary", "in some embodiments", "in another embodiment" and the like are used to represent an example, illustration or description. Any embodiment or design scheme described as "exemplary" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the word "exemplary" is intended to present the concept in a specific manner.

[0063] The "antenna" in the embodiments of the present application can include any suitable configuration, structure and / or arrangement of one or more antenna elements, components, units, assemblies and / or arrays. In some examples, the antenna can implement the transmitting and receiving functions using separate transmitting and receiving antenna elements.

[0064] It should be noted that the terms "first", "second" and the like used in the embodiments of the present application are only used for the purpose of distinguishing description, and cannot be understood as indicating or implying relative importance, nor can it be understood as indicating or implying sequence. The equal to involved in the embodiments of the present application can be used with greater than, which is applicable to the technical scheme adopted when greater than, or can be used with less than, which is applicable to the technical scheme adopted when less than. It should be noted that when equal to is used with greater than, it is not used with less than; when equal to is used with less than, it is not used with greater than.

[0065] Please refer to Figure 1 The functional module diagram of the analog signal conditioning circuit provided by the embodiments of the present application can be observed that the analog signal conditioning circuit provided by the embodiments of the present application includes a signal receiving unit 10, a frequency down conversion unit 20, an analog transmission unit 30, a frequency up conversion unit 40 and a signal transmitting unit 50.

[0066] In the embodiments of the present application, the signal receiving unit 10 is used to receive a target signal, the frequency down conversion unit 20 is connected with the signal receiving unit 10, and is used to convert the target signal from a first frequency range to a second frequency range through a frequency down conversion mixer 22, the analog transmission unit 30 is connected with the frequency down conversion unit 20, and is used to make the target signal converted to the second frequency range pass through a radio frequency cable 31 of a preset length, and divide the target signal passing through the radio frequency cable 31 into at least two target sub-signals.

[0067] Further, the up-conversion unit 40 is connected with the analog transmission unit 30, and the up-conversion unit 40 comprises at least two up-conversion branches, each of which is provided with a digital attenuator for adjusting the signal strength of the target sub-signal, and an up-conversion mixer for up-converting the target sub-signal with adjusted signal strength to a first frequency range; the signal transmitting unit 50 is connected with the up-conversion unit 40, for mixing at least two target sub-signals up-converted to the first frequency range into one mixed signal, and transmitting the mixed signal to the radar under test.

[0068] In the embodiments of the present application, the radar under test is used to transmit electromagnetic wave signals, and the signal receiving unit 10 is used to receive the electromagnetic wave signals transmitted by the radar under test, that is, Figure 1 The target signal received by the signal receiving unit 10 is the electromagnetic wave signal transmitted by the radar under test.

[0069] Further, the down-conversion unit 20 down-converts the received target signal from the first frequency range to a second frequency range, usually down-converts the target signal in the millimeter wave frequency range to a lower second frequency range, such as down-converts the target signal in the frequency range of 30GHz~300GHz to an intermediate frequency range below 10GHz, so as to facilitate the subsequent circuit part to further process it, of course, the specific frequency range of the first frequency range and the second frequency range is not limited herein.

[0070] Please refer to Figure 2 The structure schematic diagram of each unit in the analog signal conditioning circuit provided by the embodiments of the present application is shown in the figure, when the down-conversion unit 20 processes the received target signal, the target signal enters the analog transmission unit 30 connected with the down-conversion unit 20, and the analog transmission unit 30 is provided with a radio frequency cable 31 with a preset length, the target signal in the second frequency range usually has different propagation time in the radio frequency cable 31 with different lengths, so that different distances of the micro-motion target can be simulated by setting the radio frequency cable 31 with different lengths; when it is needed to simulate the micro-motion target with different distances, the length of the radio frequency cable 31 can be directly changed.

[0071] For example, when it is needed to simulate the micro-motion target with different distances of 1 meter, 2 meters, 3 meters, etc., the length of the radio frequency cable 31 can be replaced by the above-mentioned 1 meter, 2 meters, 3 meters, respectively, compared with the position of the traditional mobile radar target simulator or the radar under test, this way of replacing the radio frequency cable 31 is more simple and convenient; therefore, the actual length of the radio frequency cable 31 is not limited herein, and the technical personnel in the field can adjust it according to the actual simulation distance requirement.

[0072] As an optional implementation, when the micro-motion characteristics such as breathing and heartbeat of the human body need to be monitored, because the frequencies of breathing and heartbeat are different, the frequency of breathing is about 1 Hz to 2 Hz, and the frequency of heartbeat is about 0.1 Hz to 0.3 Hz, therefore, the target signal passing through the radio frequency cable 31 can be divided into at least two target sub-signals according to the difference between the breathing frequency and the heartbeat frequency, one target sub-signal corresponding to the breathing frequency represents the breathing micro-motion characteristics of the micro-motion target, and the other target sub-signal corresponding to the heartbeat frequency represents the heartbeat micro-motion characteristics of the micro-motion target.

[0073] Of course, the target signal can also be divided into three target sub-signals according to actual monitoring requirements, for example, on the basis of monitoring the frequencies of breathing and heartbeat, other micro-motion characteristics such as pulse signals are monitored, and the above setting modes are all feasible, and in principle, the corresponding adjustment can be made according to the number of micro-motion characteristics of the micro-motion target, and the present application does not make further limitation.

[0074] Further, the above two target sub-signals further enter the up-conversion unit 40, and at least two up-conversion branches corresponding to the two target sub-signals are arranged in the up-conversion unit 40, so that the two target sub-signals enter the corresponding one of the up-conversion branches for gain adjustment of the signals.

[0075] Specifically, taking one target sub-signal corresponding to the signal representing the breathing micro-motion characteristics of the micro-motion target and the other target sub-signal corresponding to the signal representing the heartbeat micro-motion characteristics of the micro-motion target as an example, because the analog transmission unit 30 divides the target signal passing through the radio frequency cable 31 into two target sub-signals, two up-conversion branches are arranged in the up-conversion unit 40, so that the two target sub-signals enter the corresponding up-conversion branches.

[0076] In the embodiment of the present application, a digital attenuator capable of adjusting the signal strength of the target sub-signal and an up-conversion mixer connected with the digital attenuator and capable of up-converting the target sub-signal with the adjusted signal strength to the first frequency range are arranged in each up-conversion branch.

[0077] For the convenience of description, the signal representing the breathing of the micro-motion target is referred to as a breathing signal, the up-conversion branch into which the breathing signal enters is referred to as a breathing branch, the signal representing the heartbeat of the micro-motion target is referred to as a heartbeat signal, and the up-conversion branch into which the heartbeat signal enters is referred to as a heartbeat branch, that is, the breathing branch and the heartbeat branch are both provided with corresponding digital attenuators and up-conversion mixers.

[0078] It can be understood that the digital attenuator is a common electronic device which can be used to adjust the strength of the signal in the circuit to meet different transmission requirements; and in the embodiment of the present application, the signal strength of the breathing signal can be adjusted through the digital attenuator arranged in the breathing branch, and the signal strength of the heartbeat signal can be adjusted through the digital attenuator arranged in the heartbeat branch, so as to ensure that the breathing signal and the heartbeat signal are within a suitable range.

[0079] That is, the signal strength of the breathing signal can be adjusted through the digital attenuator, so as to adjust the echo signal strength of the breathing branch, that is, the radar cross section (RCS) of the breathing signal, and the signal strength of the heartbeat signal can also be adjusted, so as to adjust the echo of the heartbeat branch, that is, the radar cross section (RCS) of the heartbeat signal. The principle and steps of how the digital attenuator adjusts the signal strength of the breathing signal and the heartbeat signal are not described in detail.

[0080] Further, the present application is arranged in the breathing branch and the heartbeat branch with an up-conversion mixer connected with the digital attenuator, through which the target sub-signal after adjusting the signal strength can be up-converted in the first frequency range.

[0081] Specifically, the breathing signal after adjusting the signal strength is up-converted to the first frequency range through the up-conversion mixer arranged in the breathing branch, and the heartbeat signal after adjusting the signal strength is up-converted to the first frequency range through the up-conversion mixer arranged in the heartbeat branch, such as the down-conversion mixer 22 arranged in the down-conversion unit 20 which down-converts the target signal with a frequency of 30GHz~300GHz to an intermediate frequency range below 10GHz, and after a series of signal conditioning, the breathing signal or the heartbeat signal in the intermediate frequency range below 10GHz is up-converted to the initial frequency range of 30GHz~300GHz through the up-conversion mixer arranged in the up-conversion unit 40. Of course, the specific frequency range of the first frequency range and the second frequency range is not limited further, and can be adjusted according to the actual simulation requirements.

[0082] As an optional implementation, please continue to refer to Figure 2 The present application also provides a signal transmitting unit 50 connected with the up-conversion unit 40, which is used to combine the at least two target sub-signals up-converted to the first frequency range into one mixed signal, that is, to combine the breathing signal up-converted to the first frequency range and the heartbeat signal up-converted to the first frequency range into one mixed signal, and then to send the mixed signal to the radar to be tested, so as to complete the simulation of the breathing and heartbeat micro-motion target.

[0083] It needs to be explained that, since the frequency of breathing is 1Hz~2Hz, the frequency of heartbeat is about 0.1Hz~0.3Hz, the frequency of breathing is different from the frequency range of heartbeat, therefore, the breathing signal and the heartbeat signal can be combined into one mixed signal, when the mixed signal is extracted through the corresponding signal algorithm, the breathing signal and the heartbeat signal will not interfere with each other, the frequency components corresponding to the breathing and the heartbeat can be accurately found, and then the breathing frequency and the heartbeat frequency are separated through filtering, peak detection and other further operations, so as to realize the simulation of the breathing and the heartbeat micro-motion target.

[0084] In the embodiments of the present application, please refer to Figure 4 In the simulation signal conditioning circuit provided by the embodiments of the present application, the Doppler frequency of the breathing branch is obtained by the difference between the input frequency F2 of the local oscillator (LO) of the up-conversion mixer 44 of the breathing branch and the input frequency F1 of the local oscillator (LO) of the down-conversion mixer 22 in the down-conversion unit 20, that is, the Doppler frequency offset1=F2-F1 corresponding to the breathing branch.

[0085] Specifically, when F1=F2, offset1=0Hz, which means that there is no moving target in the radar echo corresponding to the breathing branch, at this time, the Doppler frequency offset1 corresponding to the breathing branch is 0Hz; when F2>F1, offset1>0Hz, which means that there is a positive moving target in the radar echo corresponding to the breathing branch, at this time, the Doppler frequency offset1 corresponding to the breathing branch is positive; when F2<F1, offset1<0Hz, which means that there is a negative moving target in the radar echo corresponding to the breathing branch, at this time, the Doppler frequency offset1 corresponding to the breathing branch is negative, so the adjustment of the Doppler frequency offset1 of the moving target corresponding to the breathing branch can be realized by controlling the difference between the input frequency F2 of the local oscillator (LO) of the up-conversion mixer 44 and the input frequency F1 of the local oscillator (LO) of the down-conversion mixer 22 in the down-conversion unit 20.

[0086] Similarly, since the Doppler frequency of the heartbeat branch is obtained by the difference between the input frequency F3 of the local oscillator (LO) of the up-conversion mixer 48 of the heartbeat branch and the input frequency F1 of the local oscillator (LO) of the down-conversion mixer 22 in the down-conversion unit 20, that is, the Doppler frequency offset2=F3-F1 corresponding to the heartbeat branch.

[0087] Specifically, when F1=F3, offset2=0Hz, indicating that there is no any moving micro-motion target in the radar echo corresponding to the heartbeat branch, at this time the Doppler frequency offset2 corresponding to the breathing branch is 0Hz; when F3>F1, offset2>0Hz, indicating that there is a positive constantly-approaching micro-motion target in the radar echo corresponding to the heartbeat branch, at this time the Doppler frequency offset2 corresponding to the heartbeat branch is positive; when F3<F1, offset2<0Hz, indicating that there is a negative constantly-approaching micro-motion target in the radar echo corresponding to the heartbeat branch, at this time the Doppler frequency offset2 corresponding to the heartbeat branch is negative, so that the difference between the input frequency F3 of the local oscillator (LO) of the up-conversion mixer 48 and the input frequency F1 of the local oscillator (LO) of the down-conversion mixer 22 in the down-conversion unit 20 can realize the adjustment of the Doppler frequency offset2 of the micro-motion target corresponding to the heartbeat branch.

[0088] In the embodiment of the present application, the down-conversion mixer 22 and the at least two up-conversion mixers are all provided with corresponding phase-locked loops, and the input frequencies of the local oscillators of the down-conversion mixer 22 and the up-conversion mixers are all derived from the output frequencies of the corresponding phase-locked loops, and the plurality of phase-locked loops are all connected with the same reference source 60, so that the references of the plurality of phase-locked loops are all derived from the reference source 60.

[0089] The phase-locked loop is a feedback control system capable of realizing phase synchronization, which can make the frequency and phase of the output signal consistent with or maintain a specific relationship with the reference signal, and the same-source setting mode of such phase-locked loop can make the values of the Doppler frequencies offset1 and offset2 as small as 0.01HZ, infinitely approaching 0Hz or even equal to 0Hz, so as to simulate the micro-motion target with very low frequency or even simulate the static target.

[0090] It can be understood that by adjusting the input frequency F1 of the local oscillator signal LO of the down-conversion mixer 22, the input frequency F2 of the local oscillator signal LO of the up-conversion mixer 44 in the heartbeat branch, and the input frequency F3 of the local oscillator signal LO of the up-conversion mixer 48 of the respiration branch, the adjustment of the Doppler frequencies offset1 and offset2 corresponding to the respiration branch and the heartbeat branch can be realized, and the same source of the plurality of phase-locked loops can make offset1 and offset2 infinitely close to 0Hz, thereby realizing the adjustable Doppler frequency and realizing the transformation of the respective Doppler frequencies of the respiration branch and the heartbeat branch; the corresponding setting of the numerical control attenuator can independently control the size of the radar scattering cross section corresponding to the respiration branch and the heartbeat branch, and realize the adjustment of the respective echo signal strength; and by switching the RF cable 31 of different lengths, the micro-motion target at different distances can be simulated, without the need to move the radar target simulator or the position of the radar to be tested, and the operation is simple and convenient. That is, the analog signal conditioning circuit provided by the present application can simulate micro-motion targets of different echo strengths and different distances according to the needs, effectively improving the accuracy and reliability of radar monitoring.

[0091] In an optional embodiment, please continue to refer to Figure 4 The phase-locked loop provided by the present application includes a first phase-locked loop 61 connected with the down-conversion mixer 22, a second phase-locked loop 62 and a third phase-locked loop 63 connected with at least two up-conversion mixers. Specifically, the second phase-locked loop 62 is connected with the up-conversion mixer arranged in the respiration branch, and the third phase-locked loop 63 is connected with the up-conversion mixer arranged in the heartbeat branch.

[0092] Preferably, the reference source 60 is set as an active crystal oscillator. The active crystal oscillator usually contains an oscillation circuit inside, does not need an external oscillation circuit to drive, and can directly output a stable clock signal. The output signal frequency of the active crystal oscillator has high precision and good stability, and is usually used in electronic devices that require high-precision clocks. In the present application, the first phase-locked loop 61, the second phase-locked loop 62, and the third phase-locked loop 63 are all connected with the active crystal oscillator. By setting the first phase-locked loop 61, the second phase-locked loop 62, and the third phase-locked loop 63 to have the same structure and the same reference source, i.e., the same active crystal oscillator, the same source design of the first phase-locked loop 61, the second phase-locked loop 62, and the third phase-locked loop 63 is realized.

[0093] At this time, the input frequency of the local oscillator signal LO of the downconverter mixer 22 is derived from the output frequency F1 of the first phase-locked loop 61, the input frequency of the local oscillator signal LO of the upconverter mixer 44 in the respiratory branch is derived from the output frequency F2 of the second phase-locked loop 62, and the input frequency of the local oscillator signal LO of the upconverter mixer 48 in the heartbeat branch is derived from the output frequency F3 of the third phase-locked loop 63. This ensures that the Doppler frequencies offset1 and offset2 are infinitely close to 0Hz, thereby simulating a very low-frequency micro-movement target and realizing frequency switching of different ranges in the respiratory branch and the heartbeat branch.

[0094] As an optional implementation method, please refer to Figure 3 This is a schematic diagram of the analog signal conditioning circuit provided in the embodiment of this application. The signal receiving unit 10 provided in this application is provided with a receiving antenna 11, which receives the target signal sent by the radar under test. The downconversion unit 20 is also provided with a low noise amplifier 21 connected to the receiving antenna 11. This application connects the first input terminal of the downconversion mixer 22 to the low noise amplifier 21 and the second input terminal of the downconversion mixer 22 to the first phase-locked loop 61. The target signal is amplified by the low noise amplifier 21 and transmitted to the downconversion mixer 22. The downconversion mixer 22 downconverts the target signal from the first frequency range to the second frequency range.

[0095] Furthermore, the downconversion unit 20 provided in this application also includes a filter 23 connected to the output terminal of the downconversion mixer 22, and a first amplifier 24 connected to the filter 23. When the target signal is transmitted to the downconversion unit 22, it will first be filtered by the filter 23 to downconvert the target signal to the second frequency range, and then the filtered target signal will be amplified by the first amplifier 24 and transmitted to the analog transmission unit 30.

[0096] Specifically, this application provides at least one radio frequency cable 31 of a preset length in the analog transmission unit 30, and a power divider 32 for equally dividing the target signal is provided after the radio frequency cable 31. During this transmission process, the radio frequency cable 31 can ensure the integrity of the target signal during transmission. By connecting the radio frequency cable 31 to the first amplifier 24, the amplified target signal passes through the radio frequency cable 31 of the preset length, thereby simulating the target distance of the preset length. When different target distances need to be simulated, the radio frequency cable 31 of different lengths can be replaced as needed, which is very simple and quick.

[0097] Further, the power divider 32, also called power distributor, in the embodiment of the present application, the target signal transmitted through the radio frequency cable 31 is further transmitted to the power divider 32, and the power divider 32 divides the target signal into at least two target sub-signals with equal power.

[0098] In one specific embodiment provided by the present application, the power divider 32 divides the target signal in the second frequency range into a first target sub-signal representing a breathing signal and a second target sub-signal representing a heartbeat signal, and the power of the first target sub-signal is equal to that of the second target sub-signal.

[0099] As an optional implementation, the at least two up-conversion branches in the up-conversion unit 40 correspond to a first up-conversion branch 41 for transmitting the first target sub-signal and a second up-conversion branch 45 for transmitting the second target sub-signal, that is, the first up-conversion branch 41 corresponds to a breathing branch for transmitting a breathing signal, and the second up-conversion branch 45 corresponds to a heartbeat branch for transmitting a heartbeat signal.

[0100] Specifically, the first up-conversion branch 41 is provided with a first digital control attenuator 43 for adjusting the signal strength of the first target sub-signal, and a first up-conversion mixer 44 for up-converting the first target sub-signal with adjusted signal strength to the first frequency range, the first input end of the first up-conversion mixer 44 is connected with the first digital control attenuator 43, and the second input end of the first up-conversion mixer 44 is connected with the second phase-locked loop 62.

[0101] Similarly, the second up-conversion branch 45 is provided with a second digital control attenuator 47 for adjusting the signal strength of the second target sub-signal, and a second up-conversion mixer 48 for up-converting the second target sub-signal with adjusted signal strength to the first frequency range, the first input end of the second up-conversion mixer 48 is connected with the second digital control attenuator 47, and the second input end of the second up-conversion mixer 48 is connected with the third phase-locked loop 63.

[0102] Further, the output end of the first up-conversion mixer 44 and the output end of the second up-conversion mixer 48 are both connected with the signal transmitting unit 50.

[0103] In the embodiment of the present application, the down-conversion mixer 22 is connected with the first phase-locked loop 61, the first up-conversion mixer 44 is connected with the second phase-locked loop 62, the second up-conversion mixer 48 is connected with the third phase-locked loop 63, and the reference sources of the first phase-locked loop 61, the second phase-locked loop 62 and the third phase-locked loop 63 are all from an active crystal oscillator, and the first phase-locked loop 61, the second phase-locked loop 62 and the third phase-locked loop 63 are further set to have the same structure, so that the homologous design of the down-conversion mixer 22, the first up-conversion mixer 44 and the second up-conversion mixer 48 is realized.

[0104] By adjusting the input frequency F1 of the local oscillator signal of the down-conversion mixer 22, the input frequency F2 of the local oscillator signal of the first up-conversion mixer 44 and the input frequency F3 of the local oscillator signal of the second up-conversion mixer 48, the Doppler frequencies offset1 and offset2 of the first up-conversion branch 41 and the second up-conversion branch 45 can be adjusted.

[0105] Corresponding adjustments are made, so that the frequency changes of the respective up-conversion branches are independently controlled, the frequency switching time of the microsecond level is realized, and the frequency switching range of 0.01 Hz to several hundred kHz is realized.

[0106] In an optional embodiment, the first up-conversion branch 41 is further provided with a second amplifier 42 connected with the first digital controlled attenuator 43 and the power divider 32, and the second up-conversion branch 45 is further provided with a third amplifier 46 connected with the second digital controlled attenuator 47 and the power divider 32; the implementation principle of the second amplifier 42 and the third amplifier 46 is not described in detail herein.

[0107] As an optional implementation, the signal transmitting unit 50 further comprises a combiner 51 connected with the above-mentioned several up-conversion branches, and at least two target sub-signals up-converted to the first frequency range are combined into one mixed signal through the combiner 51.

[0108] Specifically, the output end of the first up-conversion mixer 44 and the output end of the second up-conversion mixer 48 are both connected with the combiner 51 of the signal transmitting unit 50, and the first target sub-signal and the second target sub-signal are combined into one mixed signal through the combiner 51, and then the mixed signal is transmitted to the radar to be tested through the transmitting antenna 53, so that the target signal transmitted by the radar to be tested is received through the receiving antenna 11, the target signal is processed through the analog signal processing circuit provided by the present application, and then the processed mixed signal is transmitted to the radar to be tested through the transmitting antenna 53, so that the radar target simulation with breathing, heartbeat and other micro-motion characteristics is realized.

[0109] Preferably, a band-pass filter 52 is further arranged between the combiner 51 and the transmitting antenna 53, and the mixed stray signals are filtered out through the band-pass filter 52, and the useful mixed signals in the first frequency range are reserved, so that the transmitting antenna 53 transmits the filtered mixed signals to the radar to be tested.

[0110] Please refer to Figure 6 The structure schematic diagram of the frequency multiplier in the analog signal conditioning circuit provided by the embodiment of the present application is shown in FIG. 6. The internal structures of the down-conversion mixer 22, the first up-conversion mixer 44 and the second up-conversion mixer 48 are usually integrated with a mixer circuit, a local oscillator LO frequency multiplier and an amplification circuit. The frequency of the given local oscillator signal LO can be less than 32 GHz, and the first phase-locked loop 61, the second phase-locked loop 62 and the third phase-locked loop 63 can be selected and adapted based on this.

[0111] It can be understood that there are different frequency bands of millimeter-level radars on the market, such as 24 GHz, 60 GHz, 77 GHz and 120 GHz. In order to adapt the analog signal conditioning circuit provided by the present application to the test of radars with different frequency bands, it is only necessary to replace the receiving antenna 11, the low-noise amplifier 21, the down-conversion mixer 22, the first up-conversion mixer 44, the second up-conversion mixer 48, the combiner 51, the band-pass filter 52 and the transmitting antenna 53 in the circuit with corresponding devices of the same frequency band, and the present application will not make too much repetition and description on this.

[0112] Of course, the above-mentioned simulation is only the simulation of different micro-motion characteristics of the same micro-motion target. Taking breathing and heartbeat as examples, that is, the simulation is the simulation of the micro-motion characteristics of the breathing and heartbeat of the same person. However, the simulation of different micro-motion characteristics of a second micro-motion target can also be extended on this basis.

[0113] Specifically, please refer to Figure 5 The structure schematic diagram of the analog signal conditioning circuit provided by the embodiment of the present application is shown in FIG. 7. Two power dividers 32 are further added at the output end of the above-mentioned power divider 32. The output end of the power divider 32 is normally connected with one of the power dividers 32, and the output end of the power divider 32 is connected with the other power divider 32 through a second radio frequency cable 31. A corresponding up-conversion unit 40 is arranged after the second radio frequency cable 31. Finally, a combiner 51 is further added to synthesize the different micro-motion characteristics of the two micro-motion targets, and the synthesized signals are transmitted to the radar to be tested through the transmitting antenna 53.

[0114] The second segment of the radio frequency cable 31 has the same effect as the first segment of the radio frequency cable 31, and can increase an additional second micro-motion target on the basis of the distance of the first micro-motion target. The distance of the simulated second micro-motion target is slightly farther than the distance of the first micro-motion target, and the specific distance depends on the length of the second segment of the radio frequency cable 31.

[0115] On this basis, a third or even a fourth micro-motion target can be simulated, but it should be noted that the input frequency of the local oscillator signal of the up-conversion mixer and each down-conversion mixer 22 in each micro-motion target must come from the same reference crystal oscillator, which is known to those skilled in the art.

[0116] Based on the above-mentioned analog signal conditioning circuit, the application further provides a radar simulation system, which comprises a host computer 2, a microcontroller 3, an input and output device 4, and the above-mentioned analog signal conditioning circuit 1.

[0117] As an optional embodiment, the host computer 2 and the microcontroller 3 are bidirectionally connected in communication, the input and output device 4 is bidirectionally connected in communication with the microcontroller 3, and the microcontroller 3 is bidirectionally connected in communication with the analog signal conditioning circuit 1 provided by the application.

[0118] Specifically, the radar simulation system provided by the application can receive the target signal sent by the radar to be tested through the receiving antenna 11, process the target signal through the analog signal conditioning circuit 1 provided in the radar simulation system, and send the processed signal to the radar to be tested through the transmitting antenna 53.

[0119] In the embodiment of the application, the microcontroller 3 is bidirectionally connected in communication with the analog signal conditioning circuit 1 provided by the application, and each phase-locked loop structure in the analog signal conditioning circuit 1 is the same type and is provided with a corresponding phase-locked loop chip. Therefore, the register state value of each phase-locked loop chip can be adjusted through the microcontroller 3, thereby realizing the simulation of different target states.

[0120] In an optional embodiment, the input and output device 4 can be in the form of a touch display screen, which can not only display the state of the current radar simulation system, but also enable the R&D personnel to input the test parameters that need to be simulated through the touch display screen. The touch display screen transmits the input test parameters to the microcontroller 3 through the serial port, and the microcontroller 3 translates the test parameters into register values and writes them into the corresponding phase-locked loop chip provided in the analog signal conditioning circuit 1, thereby adjusting the register state value of each phase-locked loop chip and realizing the simulation of different target states.

[0121] Of course, the microcontroller 3 also reads the register state value of the phase-locked loop chip provided in the analog signal conditioning circuit 1, and sends it to the touch display screen through the serial port, so as to facilitate the monitoring of the current radar simulation system by the researchers.

[0122] For example, the host computer 2 can be connected to the controller through a network port. The host computer 2 is a GUI (Graphical User Interface) software installed on a PC (Personal Computer). The operation mode of the GUI is similar to that of the touch display screen. On the one hand, the GUI can display the state of the current radar simulation system. On the other hand, the researchers can input the test parameters required for simulation through the operation mode of the mouse and keyboard. The GUI transmits the new test parameters to the microcontroller 3 through the network port. The microcontroller 3 translates the test parameters into register values and writes them into the corresponding phase-locked loop chip provided in the analog signal conditioning circuit 1, so as to adjust the register state value of each phase-locked loop chip and realize simulation of different target states.

[0123] Of course, the GUI also reads the register state value of the phase-locked loop chip provided in the analog signal conditioning circuit 1, and sends it to the touch display screen through the network port, so as to facilitate the monitoring of the current radar simulation system by the researchers.

[0124] As an optional embodiment, the PC host computer 2 further includes a series of API (Application Programming Interface) software libraries. By calling the API software library, the radar target simulation system can be integrated into the corresponding test system, so as to facilitate further system integration by the researchers. The calling of the API software library has been applied in the related art, and therefore will not be described further.

[0125] For other details of the radar signal simulator system for realizing the above technical solutions, reference can be made to the description of the analog signal conditioning circuit provided in the above application embodiments, which will not be described further.

[0126] The simulation signal conditioning circuit and the radar signal simulator system provided by the application can make the Doppler frequencies of the first up-conversion branch and the second up-conversion branch close to 0Hz, and can adjust the Doppler frequencies of the first up-conversion branch and the second up-conversion branch by adjusting the input frequencies of the local oscillator signals of the down-conversion mixer, the first up-conversion mixer and the second up-conversion mixer, thereby independently controlling the frequency variation of each up-conversion branch, realizing the microsecond-level frequency switching time, and realizing the frequency switching range of 0.01Hz to several hundred kHz.

[0127] The first up-conversion branch and the second up-conversion branch are correspondingly provided with the first digital attenuator and the second digital attenuator, which can control the echo intensity of each up-conversion branch, that is, the radar scattering cross section size; by changing the length of the external radio frequency cable, the micro-motion target at different distances can be simulated, without moving the radar target simulator or the position of the radar to be tested, and only the radio frequency cable with the corresponding length needs to be replaced according to the simulated distance, which is simple and convenient.

[0128] Further, the corresponding extension branch can be added on the basis of one micro-motion target, so as to realize the simulation of different micro-motion characteristics of two or more micro-motion targets; and the traditional mechanical vibration method needs to add two motors and two metal corner reflectors, which doubles the complexity of building, and the application does not need to increase additional system debugging work, reduces the test complexity and test cost.

[0129] Preferably, the application can also be applied to micro-motion targets of different millimeter wave frequency bands, and only the receiving antenna, the low-noise amplifier, the down-conversion mixer, the first up-conversion mixer, the second up-conversion mixer, the combiner, the band-pass filter and the transmitting antenna in the circuit need to be replaced with corresponding devices of the frequency band, so as to expand to the required millimeter wave frequency band; and the traditional mechanical vibration method needs to replace metal corner reflectors of different sizes to adapt to different millimeter wave frequency bands, which increases the complexity of structural design, and after replacement, recalibration and calibration are needed, which increases the test complexity.

[0130] In the embodiment of the application, through the setting of the simulation signal conditioning circuit, the system precision and service life limitations brought by the traditional mechanical vibration are eliminated, and the parameter configuration and information interaction can be performed in cooperation with the host computer, the microcontroller and the input and output devices, so as to simulate micro-motion targets with different echo intensities and different distances, and improve the reliability and accuracy of radar detection.

[0131] It can be understood that any combination of the technical features in the above embodiments can be made, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist, it should be considered that it is within the scope of the description.

[0132] The above embodiments are merely exemplary embodiments adopted for illustrating the principles of the embodiments of the present application, however, the embodiments of the present application are not limited thereto. Various modifications and improvements can be made by those of ordinary skill in the art without departing from the spirit and essence of the embodiments of the present application, and these modifications and improvements are also considered as the protection scope of the embodiments of the present application.

Claims

1. An analog signal conditioning circuit, characterized in that, include: The signal receiving unit is used to receive the target signal; A downconversion unit is used to downconvert the target signal from a first frequency range to a second frequency range via a downconversion mixer. An analog transmission unit is used to pass a target signal down-converted to the second frequency range through a radio frequency cable of a preset length, and to divide the target signal passing through the radio frequency cable into at least two target sub-signals; The upconversion unit includes at least two upconversion branches, each of which is provided with a digitally controlled attenuator for adjusting the signal strength of the target sub-signal, and an upconversion mixer for upconverting the target sub-signal with adjusted signal strength to the first frequency range. The signal transmitting unit is used to combine at least two target sub-signals up-converted to the first frequency range into a single mixed signal, and transmit the mixed signal to the radar under test; The input frequencies of the local oscillator signals of the down-conversion mixer and each of the up-conversion mixers are all derived from the output frequencies of the corresponding phase-locked loops, and the reference frequencies of the multiple phase-locked loops are all derived from the same reference source.

2. The analog signal conditioning circuit as described in claim 1, characterized in that, The phase-locked loop includes at least a first phase-locked loop connected to the down-converter mixer, and a second and a third phase-locked loop connected to a plurality of the up-converter mixers; The reference source is a reference crystal oscillator, and the first phase-locked loop, the second phase-locked loop, and the third phase-locked loop are all connected to the reference crystal oscillator.

3. The analog signal conditioning circuit as described in claim 2, characterized in that, The downconversion unit further includes a low-noise amplifier connected to the signal receiving unit, the first input terminal of the downconversion mixer is connected to the low-noise amplifier, and the second input terminal of the downconversion mixer is connected to the first phase-locked loop. The low-noise amplifier is used to amplify the target signal and transmit the amplified target signal to the downconversion mixer so that the downconversion mixer downconverts the target signal from the first frequency range to the second frequency range.

4. The analog signal conditioning circuit as described in claim 3, characterized in that, The downconversion unit further includes a filter connected to the output terminal of the downconversion mixer, and a first amplifier connected to the filter; The filter is used to filter the target signal down-converted to the second frequency range, and the first amplifier is used to amplify the filtered target signal and transmit it to the analog transmission unit.

5. The analog signal conditioning circuit as described in claim 2, characterized in that, The analog transmission unit includes at least one of the radio frequency cables and a power divider connected to the radio frequency cables; The radio frequency cable is connected to the downconversion unit to simulate a target distance of a preset length. The power divider is used to divide the target signal passing through the radio frequency cable into at least a first target sub-signal and a second target sub-signal with the same power as the first target sub-signal.

6. The analog signal conditioning circuit as described in claim 5, characterized in that, The upconversion branch includes at least a first upconversion branch for transmitting the first target sub-signal and a second upconversion branch for transmitting the second target sub-signal; The first upconversion branch is provided with a first numerically controlled attenuator for adjusting the signal strength of the first target sub-signal, and a first upconversion mixer for upconverting the first target sub-signal with adjusted signal strength to the first frequency range. The second upconversion branch is provided with a second numerically controlled attenuator for adjusting the signal strength of the second target sub-signal, and a second upconversion mixer for upconverting the second target sub-signal with adjusted signal strength to the first frequency range.

7. The analog signal conditioning circuit as described in claim 6, characterized in that, The first input terminal of the first upconverter mixer is connected to the first digitally controlled attenuator, and the second input terminal of the first upconverter mixer is connected to the second phase-locked loop. The first input terminal of the second upconversion mixer is connected to the second digitally controlled attenuator, the second input terminal of the second upconversion mixer is connected to the third phase-locked loop, and the output terminals of both the first upconversion mixer and the second upconversion mixer are connected to the signal transmitting unit.

8. The analog signal conditioning circuit as described in claim 6, characterized in that, The first upconversion branch is further provided with a second amplifier connected to the first digitally controlled attenuator and the power divider, and the second upconversion branch is further provided with a third amplifier connected to the second digitally controlled attenuator and the power divider.

9. The analog signal conditioning circuit as described in claim 1, characterized in that, The signal transmitting unit includes a combiner connected to a plurality of the up-conversion branches, and a transmitting antenna connected to the combiner; The combiner is used to combine at least two target sub-signals up-converted to the first frequency range into a single mixed signal, and the transmitting antenna is used to transmit the mixed signal to the radar under test.

10. The analog signal conditioning circuit as described in claim 9, characterized in that, A bandpass filter is also provided between the combiner and the transmitting antenna. The bandpass filter is used to filter out spurious signals in the mixed signal so that the transmitting antenna can send the filtered mixed signal to the radar under test.

11. A radar signal simulator system, characterized in that, It includes a host computer, a microcontroller bidirectionally connected to the host computer, an input / output device bidirectionally connected to the microcontroller, and an analog signal conditioning circuit as described in any one of claims 1-10.

Images