Analog signal conditioning circuit and radar signal simulator system

Abstract

The invention provides an analog signal conditioning circuit and a radar signal simulator system, and the analog signal conditioning circuit comprises a signal receiving unit which is used for receiving a target signal; a down-conversion unit for down-converting the target signal from the first frequency range to a second frequency range through a down-conversion mixer; the analog transmission unit is used for dividing a target signal passing through the radio frequency cable into two target sub-signals; the up-conversion unit is used for carrying out up-conversion on the target sub-signal of which the signal strength is adjusted to a first frequency range through an up-conversion mixer; the signal transmitting unit is used for combining the two target sub-signals into one path of frequency mixing signal; wherein the input frequencies of local oscillation signals of the down-conversion mixer and each up-conversion mixer are all from the output frequencies of the correspondingly arranged phase-locked loops, and the reference frequencies of the plurality of phase-locked loops are all from the same reference source, so that micro-motion targets with different echo intensities and different distances are simulated; and the reliability of radar detection is improved.

Description

Technical Field

[0001] The present application belongs to the field of radar signal simulation technology, and specifically relates to an analog signal conditioning circuit and a radar signal simulator system. Background Art

[0002] With the rapid development of science and technology, radar microwave technology is being used more and more widely in the field of sensors. Millimeter wave radar is a sensor that can measure speed and distance. It can transmit electromagnetic waves, receive electromagnetic wave signals reflected back after encountering the target, and analyze the echo signals to detect the distance, speed and other information of the target. It is now widely used in military, medical, industrial and other technical fields.

[0003] The human body's breathing and heartbeat will cause tiny movements in parts such as the chest cavity. The chest cavity will rise and fall regularly when breathing, and the heartbeat will also produce weak but continuous vibrations. The micro-motion characteristics of the human body such as breathing and heartbeat can be monitored by radar equipment with high frequency and accuracy, such as millimeter-wave radar, so as to perform remote, non-contact vital signs monitoring of patients. In related technologies, radar simulation and testing are usually achieved through mechanical methods. Specifically, the electromagnetic wave signal emitted by the radar is reflected back along the original path by a motor-driven metal corner reflector, 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, and long-term use will reduce the accuracy and life of the system. As the system accuracy decreases, regular calibration and maintenance are required, which increases the cost and complexity of use.

[0004] Furthermore, since the structural dimensions of the metal corner reflector of the above-mentioned mechanical vibration radar target simulator are fixed, the signal strength of the radar echo is fixed during testing. However, simulated targets at different distances and with different scattering cross-sectional areas will produce echo signals of different intensities. For example, infants, children, adults, and patients have different radar scattering cross-sections and echo intensities. Therefore, the traditional method of simulating micro-motion targets through mechanical vibration will make it impossible for the radar target simulator to simulate radar echoes of different intensities, limiting the reliability and usage scenarios of the radar. Summary of the invention

[0005] The present application provides an analog signal conditioning circuit and a radar signal simulator system, which can simulate micro-motion targets of different echo intensities and different distances according to needs, thereby improving the accuracy and reliability of radar detection of micro-motion targets.

[0006] In order to solve the above technical problems, the present application provides an analog signal conditioning circuit, comprising:

[0007] A signal receiving unit, used for receiving 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 through a down-conversion mixer;

[0009] an analog transmission unit, configured to allow the target signal down-converted to the second frequency range to pass 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;

[0010] an up-conversion unit, comprising at least two up-conversion branches, each of which is provided with a digitally controlled attenuator for adjusting the signal strength of the target sub-signal, and an up-conversion mixer for up-converting the target sub-signal after adjusting the signal strength to the first frequency range;

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

[0012] The input frequencies of the local oscillator signals of the down-conversion mixer and each of the up-conversion mixers are derived from the output frequencies of corresponding phase-locked loops, and the reference frequencies of several phase-locked loops are derived from the same reference source.

[0013] As a further improvement of the present application, the phase-locked loop at least includes a first phase-locked loop connected to the down-conversion mixer, and a second phase-locked loop and a third phase-locked loop connected to 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 all connected to the reference crystal oscillator.

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

[0016] The low noise amplifier is used 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 includes a filter connected to the output end of the down-conversion mixer, and a first amplifier connected to the filter;

[0018] The filter is used to filter the target signal that is 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.

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

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

[0021] As a further improvement of the present application, the up-conversion branch at least includes a first up-conversion branch for transmitting the first target sub-signal, and a second up-conversion branch for transmitting the second target sub-signal;

[0022] The first up-conversion branch is provided with a first digitally controlled attenuator for adjusting the signal strength of the first target sub-signal, and a first up-conversion mixer for up-converting the first target sub-signal after adjusting the signal strength to the first frequency range;

[0023] The second up-conversion branch is provided with a second digitally controlled attenuator for adjusting the signal strength of the second target sub-signal, and a second up-conversion mixer for up-converting the second target sub-signal after adjusting the signal strength to the first frequency range.

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

[0025] The first input end of the second up-conversion mixer is connected to the second phase-locked loop, the second input end of the second up-conversion mixer is connected to the third phase-locked loop, and the output ends of the first up-conversion mixer and the second up-conversion mixer are both connected to the signal transmitting 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 digitally controlled attenuator and the power divider, and the second up-conversion branch is further provided with a third amplifier connected to the second digitally controlled attenuator and the power divider.

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

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

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

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

[0031] A host computer, a microcontroller connected to the host computer in two-way communication, an input / output device connected to the microcontroller in two-way communication, and the analog signal conditioning circuit described above.

[0032] Compared with the prior art, the analog signal conditioning circuit and radar signal simulator system provided by the present application, since 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, the Doppler frequency of the first up-conversion branch and the second up-conversion branch can be made close to 0 Hz. By adjusting the input frequency of the local oscillator signal of the down-conversion mixer, the input frequency of the local oscillator signal of the first up-conversion mixer and the input frequency of the local oscillator signal of the second up-conversion mixer, the Doppler frequency of the first up-conversion branch and the second up-conversion branch can be adjusted, thereby independently controlling the frequency changes of each up-conversion branch, achieving a frequency switching time of microseconds, and achieving a 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 a first digitally controlled attenuator and a second digitally controlled attenuator, which can control the echo intensity of each up-conversion branch or the size of the radar scattering cross section; by changing the length of the external RF cable, micro-motion targets at different distances can be simulated without moving the radar target simulator or the position of the radar to be tested. It is only necessary to replace the RF cable of the corresponding length according to the simulated distance. The operation is simple, convenient and fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 A functional module diagram of an analog signal conditioning circuit provided in an embodiment of the present application;

[0036] Figure 2 A schematic diagram of the structure of each unit in the analog signal conditioning circuit provided in an embodiment of the present application;

[0037] Figure 3 A schematic diagram of the structure of an analog signal conditioning circuit provided in an embodiment of the present application;

[0038] Figure 4 A schematic diagram of the structure of a reference crystal oscillator in an analog signal conditioning circuit provided in an embodiment of the present application;

[0039] Figure 5 A schematic diagram of a structure in which a micro-motion target is added to the analog signal conditioning circuit provided in an embodiment of the present application;

[0040] Figure 6 A schematic diagram of the structure of a frequency multiplier in an analog signal conditioning circuit provided in an embodiment of the present application;

[0041] Figure 7 A schematic diagram of the structure of a radar signal simulator system provided in an embodiment of the present application;

[0042] Description of reference numerals:

[0043] 1-Analog signal conditioning circuit; 2-Host computer; 3-Microcontroller; 4-Input and output devices;

[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-RF cable; 32-power divider;

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

[0048] 50-signal transmitting unit; 51-combiner; 52-bandpass 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 solution and advantages of the embodiment of the present application more clear, the embodiment of the present application is further described in detail below in conjunction with the drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the embodiment of the present application and are not used to limit the embodiment of the present application.

[0051] In the description of the embodiments of the present application, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise clearly and specifically limited. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0052] In order to make the description of the disclosed content more detailed and complete, the following is an illustrative description of the implementation methods and specific embodiments of the embodiments of the present application; however, this is not the only form of implementing or using the specific embodiments of the embodiments of the present application. The implementation methods cover the features of multiple specific embodiments and the method steps and sequences used to construct and operate these specific embodiments. However, other specific embodiments can also be used to achieve the same or equal functions and step sequences.

[0053] With the rapid development of science and technology, radar microwave technology is being used more and more widely in the field of sensors. Millimeter wave radar is a sensor that can measure speed and distance. It can transmit electromagnetic waves, receive electromagnetic wave signals reflected back after encountering the target, and analyze the echo signals to detect the distance, speed and other information of the target. It is now widely used in military, medical, industrial and other technical fields.

[0054] The human body's breathing and heartbeat will cause tiny movements in parts such as the chest cavity. The chest cavity will rise and fall regularly when breathing, and the heartbeat will also produce weak but continuous vibrations. The micro-motion characteristics of the human body, such as breathing and heartbeat, can be monitored through millimeter-wave radar and other radar equipment with high frequency and accuracy, so as to perform remote, non-contact vital signs monitoring of patients. Accurate monitoring of breathing and heartbeat during sleep 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 the millimeter-level radar hit the human body, a Doppler effect will occur when interacting with moving targets. The speed changes of the human body's breathing and heartbeat movements will cause the reflected radar waves to have a corresponding frequency shift. 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-level radar that can detect micro-motion features such as breathing and heartbeat needs to be developed and tested in mass production through a radar target simulator, so as to simulate and test simulated targets of different distances and different RCS (Radar Cross Section) sizes.

[0057] In related technologies, radar simulation and testing is 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 the original path, 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, and long-term use will reduce the accuracy and life of the system. As the system accuracy decreases, regular calibration and maintenance are required, which increases the cost and complexity of use.

[0058] Furthermore, since the structural dimensions of the metal corner reflector of the above-mentioned mechanical vibration radar target simulator are fixed, the signal strength of the radar echo is fixed during testing. Simulated targets at different distances and with different scattering cross-sectional areas will produce echo signals of different intensities. For example, infants, children, adults, and patients have different radar scattering cross-sections and echo intensities. Therefore, the traditional mechanical vibration method of simulating micro-motion targets will make it impossible for the radar target simulator to simulate radar echoes of different intensities, resulting in limited reliability of radar detection and inability to be applied to more usage scenarios.

[0059] In view of this, please refer to Figure 1-Figure 7 The embodiment of the present application provides an analog signal conditioning circuit and a radar signal simulator system, which can simulate micro-motion targets of different echo intensities and different distances according to needs, thereby improving the accuracy and reliability of radar detection of micro-motion targets.

[0060] It can be understood that in the embodiments of the present application, "or" describes the association relationship of associated objects, indicating that two relationships may exist. For example, A or B can represent: A exists alone, and B exists alone, where A and B can be singular or plural.

[0061] The term "connection" involved in this application describes the connection relationship between two objects and can represent two connection relationships. For example, the connection between A and B can represent two situations: A is directly connected to B, and A is connected through C and B.

[0062] In the embodiments of the present application, "exemplary", "in some embodiments", "in another embodiment", etc. are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present concepts in a concrete way.

[0063] In embodiments of the present application, an "antenna" may include any suitable configuration, structure and / or arrangement of one or more antenna elements, components, units, assemblies and / or arrays. In some examples, an antenna may use separate transmit and receive antenna elements to implement transmit and receive functions.

[0064] It should be pointed out that the words "first", "second" and the like involved in the embodiments of the present application are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order. The words "equal to" involved in the embodiments of the present application can be used in conjunction with "greater than", and are applicable to the technical solutions adopted when "greater than" is used, and can also be used in conjunction with "less than", and are applicable to the technical solutions adopted when "less than" is used. It should be noted that when "equal to" is used in conjunction with "greater than", it cannot be used in conjunction with "less than"; when "equal to" is used in conjunction with "less than", it cannot be used in conjunction with "greater than".

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

[0066] In an embodiment of the present application, a signal receiving unit 10 is used to receive a target signal, a down-conversion unit 20 is connected to the signal receiving unit 10, and is used to down-convert the target signal from a first frequency range to a second frequency range through a down-conversion mixer 22, and an analog transmission unit 30 is connected to the down-conversion unit 20, and is used to allow the target signal down-converted to the second frequency range to 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] Furthermore, the up-conversion unit 40 is connected to the analog transmission unit 30, and the up-conversion unit 40 includes at least two up-conversion branches, each of which is provided with a digitally controlled attenuator for adjusting the signal strength of the target sub-signal, and an up-conversion mixer for up-converting the target sub-signal after adjusting the signal strength to the first frequency range; the signal transmitting unit 50 is connected to the up-conversion unit 40, and is used to combine at least two target sub-signals up-converted to the first frequency range into one mixed signal, and send the mixed signal to the radar to be tested.

[0068] In the embodiment of the present application, the radar to be tested 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 to be tested, that is, Figure 1 The target signal received by the signal receiving unit 10 is an electromagnetic wave signal emitted by the radar to be tested.

[0069] Furthermore, the down-conversion unit 20 down-converts the received target signal from the first frequency range to the second frequency range, usually down-converting the target signal in the millimeter wave frequency band to a lower second frequency range, such as down-converting the target signal in the frequency range of 30GHz to 300GHz to an intermediate frequency range below 10GHz, so as to facilitate further processing by subsequent circuit parts. Of course, the present application does not further limit the specific frequency ranges of the above-mentioned first frequency range and the second frequency range.

[0070] Please refer to Figure 2 , is a structural schematic diagram of each unit in the analog signal conditioning circuit provided in an embodiment of the present application. After the down-conversion unit 20 performs down-conversion processing on the received target signal, the target signal enters the analog transmission unit 30 connected to the down-conversion unit 20. The analog transmission unit 30 is provided with a radio frequency cable 31 of a preset length. The propagation time of the target signal in the second frequency range in the radio frequency cables 31 of different lengths is usually different. Therefore, the micro-motion targets at different distances can be simulated by setting radio frequency cables 31 of different lengths; when it is necessary to simulate micro-motion targets at different distances, the length of the radio frequency cable 31 can be directly changed.

[0071] For example, when it is necessary to simulate micro-motion targets at different distances such as 1 meter, 2 meters, and 3 meters, it is only necessary to change the length of the RF cable 31 to the above-mentioned 1 meter, 2 meters, and 3 meters. Compared with the position of traditional mobile radar target simulators or the radar to be tested, this method of replacing the RF cable 31 is simpler to operate and more convenient and quick; therefore, the present application does not impose further restrictions on the actual length of the RF cable 31, and technical personnel in this field can make corresponding adjustments according to the actual simulation distance requirements.

[0072] As an optional implementation, when it is necessary to monitor micro-motion characteristics such as human breathing and heartbeat, since the frequencies of breathing and heartbeat are different, usually the breathing frequency is about 1Hz to 2Hz, and the heartbeat frequency is about 0.1Hz to 0.3Hz, 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, so that one of the target sub-signals 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 needs. For example, on the basis of the above-mentioned breathing and heartbeat frequency monitoring, other micro-motion features such as pulse signals can be added for monitoring. The above settings are all feasible. In principle, corresponding adjustments can be made based on the specific number of micro-motion features of the micro-motion target. This application does not impose any further restrictions on this.

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

[0075] Specifically, one of the target sub-signals corresponds to the signal representing the respiratory micro-motion characteristics of the micro-motion target, and the other target sub-signal corresponds to the signal representing the heartbeat micro-motion characteristics of the micro-motion target. Since the analog transmission unit 30 divides the target signal passing through the RF cable 31 into two target sub-signals, two up-conversion branches are correspondingly arranged in the up-conversion unit 40 to allow the two target sub-signals to enter the corresponding up-conversion branches.

[0076] In an embodiment of the present application, each up-conversion branch is provided with a digitally controlled attenuator capable of adjusting the signal strength of the target sub-signal, and an up-conversion mixer connected to the digitally controlled attenuator capable of up-converting the target sub-signal after adjusting the signal strength to the first frequency range.

[0077] For the sake of convenience of description, the signal representing the breathing of the micro-motion target is called the breathing signal, the up-conversion branch into which the breathing signal enters is called the breathing branch, the signal representing the heartbeat of the micro-motion target is called the heartbeat signal, and the up-conversion branch into which the heartbeat signal enters is called the heartbeat branch. That is, corresponding digitally controlled attenuators and up-conversion mixers are provided in both the breathing branch and the heartbeat branch.

[0078] It can be understood that the digitally controlled 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 by the digitally controlled attenuator set in the breathing branch, and the signal strength of the heartbeat signal can be adjusted accordingly by the digitally controlled attenuator set in the heartbeat branch, thereby ensuring that the breathing signal and the heartbeat signal are within an appropriate range.

[0079] That is to say, the signal strength of the breathing signal can be adjusted by the digitally controlled attenuator, thereby adjusting the echo signal strength of the breathing branch, that is, the radar cross section (RCS) of the breathing signal. Similarly, the signal strength of the heartbeat signal can also be adjusted, thereby adjusting the echo size of the heartbeat branch, that is, the radar cross section (RCS) of the heartbeat signal. The present application does not elaborate on the principles and steps of how the digitally controlled attenuator adjusts the signal strength of the breathing signal and the heartbeat signal.

[0080] Furthermore, the present application also provides an up-conversion mixer connected to the digitally controlled attenuator in the respiratory branch and the heartbeat branch, through which the target sub-signal with adjusted signal strength can be up-converted within the first frequency range.

[0081] Specifically, the breathing signal after adjusting the signal strength is up-converted to the first frequency range by the up-conversion mixer set in the breathing branch, and the heartbeat signal after adjusting the signal strength is up-converted to the first frequency range by the up-conversion mixer set in the heartbeat branch, such as the down-conversion mixer 22 set in the down-conversion unit 20 down-converts the target signal of 30GHz to 300GHz to the intermediate frequency range below 10GHz, and after a series of signal conditioning, the breathing signal or heartbeat signal in the intermediate frequency range below 10GHz is up-converted to the initial frequency range of 30GHz to 300GHz by the up-conversion mixer set in the up-conversion unit 40. Of course, the present application does not impose further restrictions on the specific frequency ranges of the first frequency range and the second frequency range, and can be adjusted accordingly according to actual simulation requirements.

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

[0083] It should be noted that since the breathing frequency is 1Hz~2Hz and the heartbeat frequency is about 0.1Hz~0.3Hz, the breathing frequency is different from the frequency range of the heartbeat. Therefore, the breathing signal and the heartbeat signal can be combined into a mixed signal. When the mixed signal is subsequently extracted through the corresponding signal algorithm, there will be no interference between the breathing signal and the heartbeat signal. The frequency components corresponding to breathing and heartbeat can be accurately found, and then further operations such as filtering and peak detection can be performed to separate the breathing frequency and heartbeat frequency, thereby realizing the simulation of breathing and heartbeat micro-motion targets.

[0084] In the embodiments of this application, please refer to Figure 4 , is a schematic diagram of the structure of the reference crystal oscillator in the analog signal conditioning circuit provided in an embodiment of the present application. The Doppler frequency of the respiratory branch is obtained by the difference between the input frequency F2 of the local oscillator signal (Local Oscillator, LO) of the up-conversion mixer 44 of the respiratory branch and the input frequency F1 of the local oscillator signal LO of the down-conversion mixer 22 in the down-conversion unit 20, that is, the Doppler frequency offset1 corresponding to the respiratory branch is F2-F1.

[0085] Specifically, when F1=F2, offset1=0Hz, indicating that there is no moving target in the radar echo corresponding to the breathing branch, and the Doppler frequency offset1 corresponding to the breathing branch is 0Hz at this time; when F2>F1, offset1>0Hz, indicating that the radar echo corresponding to the breathing branch has a micro-moving target that is approaching in the forward direction, and the Doppler frequency offset1 corresponding to the breathing branch is a positive number; when F2<F1, offset1<0Hz, indicating that the radar echo corresponding to the breathing branch has a micro-moving target that is approaching in the reverse direction, and the Doppler frequency offset1 corresponding to the breathing branch is a negative number. In this way, the Doppler frequency offset1 of the micro-moving target corresponding to the breathing branch can be adjusted by controlling the difference between the input frequency F2 of the local oscillator signal (Local Oscillator, LO) of the up-conversion mixer 44 and the input frequency F1 of the local oscillator signal 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 signal (LO) of the up-conversion mixer 48 of the heartbeat branch and the input frequency F1 of the local oscillator signal LO of the down-conversion mixer 22 in the down-conversion unit 20, the Doppler frequency corresponding to the heartbeat branch is offset2 = F3-F1.

[0087] Specifically, when F1=F3, offset2=0Hz, indicating that there is no moving micro-motion target in the radar echo corresponding to the heartbeat branch, and the Doppler frequency offset2 corresponding to the respiratory branch is 0Hz at this time; when F3>F1, offset2>0Hz, indicating that the radar echo corresponding to the heartbeat branch has a micro-motion target approaching in the forward direction, and the Doppler frequency offset2 corresponding to the heartbeat branch is a positive number; when F3<F1, offset2<0Hz, indicating that the radar echo corresponding to the heartbeat branch has a micro-motion target approaching in the reverse direction, and the Doppler frequency offset2 corresponding to the heartbeat branch is a negative number. In this way, the Doppler frequency offset2 of the micro-motion target corresponding to the heartbeat branch can be adjusted by controlling the difference between the input frequency F3 of the local oscillator signal (Local Oscillator, LO) of the up-conversion mixer 48 and the input frequency F1 of the local oscillator signal LO of the down-conversion mixer 22 in the down-conversion unit 20.

[0088] In an embodiment of the present application, the down-conversion mixer 22 and at least two up-conversion mixers are provided with corresponding phase-locked loops, and the input frequencies of the local oscillator signals of the down-conversion mixer 22 and the up-conversion mixers are derived from the output frequencies of the correspondingly set phase-locked loops. Multiple phase-locked loops are connected to the same reference source 60, so that the reference sources of the multiple phase-locked loops are derived from the reference source 60.

[0089] A phase-locked loop is a feedback control system that can achieve phase synchronization, which can keep the frequency and phase of the output signal consistent with the reference signal or maintain a specific relationship. The homologous setting of the phase-locked loop can make the values ​​of Doppler frequency offset1 and offset2 as small as 0.01HZ, infinitely close to 0Hz or even equal to 0Hz, thereby simulating very low-frequency micro-motion targets or even stationary targets.

[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 in the respiratory branch, the Doppler frequencies offset1 and offset2 corresponding to the respiratory branch and the heartbeat branch can be adjusted, and the setting of multiple phase-locked loops with the same source can make offset1 and offset2 infinitely close to 0Hz, thereby achieving any adjustable Doppler frequency and realizing the respiratory branch and the heartbeat branch. The Doppler frequencies of the two branches are transformed; the sizes of the radar scattering cross sections corresponding to the respiratory branch and the heartbeat branch can be independently controlled by the corresponding numerically controlled attenuators, so as to adjust the strength of the echo signals of the two branches; and by switching the RF cables 31 of different lengths, the micro-motion targets at different distances can be simulated without moving the radar target simulator or the position of the radar to be tested, and the operation is simple, convenient and fast; that is to say, the analog signal conditioning circuit provided in the present application can simulate micro-motion targets at different distances and different echo intensities according to the needs, thereby effectively improving the accuracy and reliability of radar monitoring.

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

[0092] Preferably, the present application sets the reference source 60 as an active crystal oscillator. The active crystal oscillator usually includes an oscillation circuit inside, does not need an external oscillation circuit to drive, can directly output a stable clock signal, and the output signal has high frequency accuracy and good stability, and is usually used in electronic devices that require high-precision clocks. The present application sets the first phase-locked loop 61, the second phase-locked loop 62 and the third phase-locked loop 63 to be connected to 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 reference source is the same active crystal oscillator, the homologous design of the first phase-locked loop 61, the second phase-locked loop 62 and the third phase-locked loop 63 is achieved.

[0093] At this time, the input frequency of the local oscillator signal LO of the down-conversion 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 up-conversion mixer 44 set 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 up-conversion mixer 48 set in the heartbeat branch is derived from the output frequency F3 of the third phase-locked loop 63, ensuring that the Doppler frequencies offset1 and offset2 are infinitely close to 0Hz, thereby simulating micro-motion targets with very low frequencies and realizing frequency switching in different ranges of the respiratory branch and the heartbeat branch.

[0094] As an optional implementation, please refer to Figure 3 , is a structural schematic diagram of an analog signal conditioning circuit provided in an embodiment of the present application. A receiving antenna 11 is provided in the signal receiving unit 10 provided in the present application. The target signal sent by the radar to be tested is received by the receiving antenna 11. A low-noise amplifier 21 connected to the receiving antenna 11 is also provided in the down-conversion unit 20. The present application connects a first input end of a down-conversion mixer 22 to the low-noise amplifier 21, connects a second input end of the down-conversion mixer 22 to a first phase-locked loop 61, amplifies the target signal by the low-noise amplifier 21, transmits the amplified target signal to the down-conversion mixer 22, and down-converts the target signal from the first frequency range to the second frequency range by the down-conversion mixer 22.

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

[0096] Specifically, the present application provides at least one RF cable 31 of a preset length in the analog transmission unit 30, and a power divider 32 for equally dividing the target signal is also provided after the RF cable 31; during this transmission process, the RF cable 31 can ensure the integrity of the target signal during the transmission process, and the RF cable 31 is connected to the first amplifier 24 so that the amplified target signal passes through the RF cable 31 of the preset length, thereby simulating a target distance of the preset length. When different target distances need to be simulated, RF cables 31 of different lengths can be replaced according to needs, which is very simple and quick.

[0097] Furthermore, the power divider 32 (Power Divider) is also called a power distributor. In the embodiment of the present application, the target signal passing through the RF cable 31 will be further transmitted to the power divider 32, and then the target signal will be divided into at least two target sub-signals of equal power by the power divider 32.

[0098] In a specific embodiment provided in 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 with equal power, and the power of the first target sub-signal is equal to that of the second target sub-signal.

[0099] As an optional implementation, at least two up-conversion branches provided in the up-conversion unit 40 correspond to a first up-conversion branch 41 for transmitting a first target sub-signal, and a second up-conversion branch 45 for transmitting a 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 present application provides a first digitally controlled attenuator 43 for adjusting the signal strength of the first target sub-signal in the first up-conversion branch 41, and a first up-conversion mixer 44 for up-converting the first target sub-signal after adjusting the signal strength to a first frequency range. The first input end of the first up-conversion mixer 44 is connected to the first digitally controlled attenuator 43, and the second input end of the first up-conversion mixer 44 is connected to the second phase-locked loop 62.

[0101] Similarly, the second up-conversion branch 45 is provided with a second digitally controlled 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 after adjusting the signal strength to the first frequency range, and the first input end of the second up-conversion mixer 48 is connected to the second phase-locked loop 62, and the second input end of the second up-conversion mixer 48 is connected to the third phase-locked loop 63.

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

[0103] In the embodiment of the present application, the down-conversion mixer 22 is connected to the first phase-locked loop 61, the first up-conversion mixer 44 is connected to the second phase-locked loop 62, the second up-conversion mixer 48 is connected to 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 structures of the first phase-locked loop 61, the second phase-locked loop 62 and the third phase-locked loop 63 are further arranged to be the same, thereby realizing the homologous design of the down-conversion mixer 22, the first up-conversion mixer 44 and the second up-conversion mixer 48.

[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 accordingly, thereby independently controlling the frequency changes of each up-conversion branch, achieving a frequency switching time of microseconds, and achieving a frequency switching range of 0.01 Hz to several hundred kHz.

[0105] In an optional embodiment, the first up-conversion branch 41 is also provided with a second amplifier 42 connected to the first digitally controlled attenuator 43 and the power divider 32, and the second up-conversion branch 45 is also provided with a third amplifier 46 connected to the second digitally controlled attenuator 47 and the power divider 32; the present application does not elaborate on the implementation principles of the above-mentioned second amplifier 42 and third amplifier 46.

[0106] As an optional implementation, the signal transmitting unit 50 provided in the present application further includes a combiner 51 connected to the above-mentioned plurality of up-conversion branches, and the at least two target sub-signals up-converted to the first frequency range are combined into one mixed signal through the combiner 51.

[0107] 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 to the combiner 51 of the signal transmitting unit 50. The first target sub-signal and the second target sub-signal are combined into a mixed signal through the combiner 51, and then the mixed signal is sent to the radar under test through the transmitting antenna 53. In this way, the target signal sent by the radar under test is received by the receiving antenna 11, the target signal is conditioned by the analog signal conditioning circuit provided in the present application, and then the conditioned mixed signal is sent to the radar under test through the transmitting antenna 53, thereby realizing the simulation of radar targets with micro-motion characteristics such as breathing and heartbeat.

[0108] Preferably, the present application further provides a bandpass filter 52 between the combiner 51 and the transmitting antenna 53, through which the spurious signals after mixing are filtered out, and the useful mixed signals within the first frequency range are retained, so that the transmitting antenna 53 sends the filtered mixed signals to the radar to be tested.

[0109] Please refer to Figure 6 , which is a structural diagram of the frequency multiplier in the analog signal conditioning circuit provided in the embodiment of the present application, 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 amplifier circuit. The frequency of the local oscillator signal LO provided can usually be less than 32 GHz, based on which the first phase-locked loop 61, the second phase-locked loop 62 and the third phase-locked loop 63 can be selected to adapt.

[0110] It is understandable that the millimeter-level radars currently on the market have different frequency bands such as 24 GHz, 60 GHz, 77 GHz and 120 GHz. In order to make the analog signal conditioning circuit provided in this application adapt to the radar tests of these 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 bandpass filter 52 and the transmitting antenna 53 in the circuit with devices of the corresponding frequency band. This application will not go into details about this.

[0111] Of course, what is provided above is only the simulation of different micro-motion characteristics of the same micro-motion target. Taking breathing and heartbeat as an example, that is to say, the simulation is of the micro-motion characteristics of breathing and heartbeat of the same person. However, it can also be expanded on this basis to add the simulation of different micro-motion characteristics of a second micro-motion target.

[0112] For details, please refer to Figure 5 , which is a structural schematic diagram of adding a micro-motion target to the analog signal conditioning circuit provided in an embodiment of the present application, two more power dividers 32 can be added to the output end of the above-mentioned power divider 32, the output end of the power divider 32 and one of the power dividers 32 are normally connected, a second section of RF cable 31 is set between the output end of the power divider 32 and the other power divider 32, and a corresponding up-conversion unit 40 is set after the second section of RF cable 31, and finally a combiner 51 is added to synthesize the different micro-motion characteristics of the two micro-motion targets, and transmit them to the radar to be tested through the transmitting antenna 53.

[0113] The function is the same as that of the first section of RF cable 31. At this time, adding the second section of RF cable 31 can add an additional second micro-motion target based on the corresponding distance of the first micro-motion target. The distance of the simulated second micro-motion target will be slightly farther than the distance of the first micro-motion target. As for the specific distance, it depends on the length of the second section of RF cable 31.

[0114] On this basis, the simulation of different micro-motion characteristics of a third or even a fourth micro-motion target can be added. However, it should be noted that no matter how many micro-motion targets are added, the input frequency of the local oscillator signal of the up-conversion mixer and the several down-conversion mixers 22 set in each micro-motion target must be derived from the same reference crystal oscillator, as technical personnel in this field should know.

[0115] Based on the above analog signal conditioning circuit, the present application also provides a radar simulation system, which includes a host computer 2, a microcontroller 3, an input and output device 4 and the above analog signal conditioning circuit 1.

[0116] As an optional implementation, the present application connects the above-mentioned host computer 2 with the microcontroller 3 for bidirectional communication, the input and output device 4 is bidirectionally connected to the microcontroller 3 for bidirectional communication, and the microcontroller 3 is bidirectionally connected to the analog signal conditioning circuit 1 provided in the present application for bidirectional communication.

[0117] Specifically, the radar simulation system provided by the present 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 set in the radar simulation system, and send the processed signal to the radar to be tested through the transmitting antenna 53.

[0118] In the embodiment of the present application, since the microcontroller 3 is bidirectionally connected to the analog signal conditioning circuit 1 provided in the present application, and the phase-locked loop structures and types in the analog signal conditioning circuit 1 are the same and are all provided with corresponding phase-locked loop chips, the register state values ​​of each phase-locked loop chip can be adjusted through the microcontroller 3, thereby realizing the simulation of different target states.

[0119] In an optional embodiment, the input-output device 4 can be set to the form of a touch screen, which can not only display the current status of the radar simulation system, but also allow R&D personnel to input the test parameters that need to be simulated through the touch screen. The touch screen transmits the input test parameters to the microcontroller 3 through the serial port. The microcontroller 3 translates the test parameters into register values ​​and writes them into the corresponding phase-locked loop chip set in the analog signal conditioning circuit 1, thereby adjusting the register state values ​​of each phase-locked loop chip to achieve simulation of different target states.

[0120] Of course, the microcontroller 3 will also read the register status value of the phase-locked loop chip set in the analog signal conditioning circuit 1, and send it to the touch screen through the serial port, so as to facilitate R&D personnel to monitor the current radar simulation system.

[0121] Exemplarily, the host computer 2 and the controller can be connected through a network port. The host computer 2 here is a GUI (Graphical User Interface) software installed on a PC (Personal Computer). The operation method of the GUI is similar to that of a touch screen. On the one hand, the GUI can display the current status of the radar simulation system. On the other hand, R&D personnel can input the test parameters that need to be simulated through the operation of the mouse and keyboard. The GUI then 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 set in the analog signal conditioning circuit 1, thereby adjusting the register state values ​​of each phase-locked loop chip to achieve simulation of different target states.

[0122] Of course, the GUI will also read the register status value of the phase-locked loop chip set in the analog signal conditioning circuit 1, and send it to the touch screen through the network port, so as to facilitate R&D personnel to monitor the current radar simulation system.

[0123] As an optional implementation, the PC host computer 2 also 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, thereby facilitating further system integration by R&D personnel. As for the calling of the API software library, it has been applied in related technologies, so this application will not be further elaborated on this.

[0124] For other details about how the radar signal simulator system implements the above technical solution, please refer to the description of the analog signal conditioning circuit provided in the above application embodiment, which will not be repeated here.

[0125] The analog signal conditioning circuit and radar signal simulator system provided by the present application, since 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, the Doppler frequencies of the first up-conversion branch and the second up-conversion branch can be made close to 0 Hz. By adjusting the input frequency of the local oscillator signal of the down-conversion mixer, the input frequency of the local oscillator signal of the first up-conversion mixer and the input frequency of the local oscillator signal of the second up-conversion mixer, the Doppler frequencies of the first up-conversion branch and the second up-conversion branch can be adjusted, thereby independently controlling the frequency changes of each up-conversion branch, achieving a frequency switching time of microseconds, and achieving a frequency switching range of 0.01 Hz to several hundred kHz.

[0126] The first up-conversion branch and the second up-conversion branch are correspondingly provided with a first digitally controlled attenuator and a second digitally controlled attenuator, which can control the echo intensity of each up-conversion branch or the size of the radar scattering cross section; by changing the length of the external RF cable, micro-motion targets at different distances can be simulated without moving the radar target simulator or the position of the radar to be tested. It is only necessary to replace the RF cable of the corresponding length according to the simulated distance. The operation is simple, convenient and fast.

[0127] Furthermore, corresponding extension branches can be added on the basis of a micro-motion target to simulate different micro-motion characteristics of two or more micro-motion targets; while the traditional mechanical vibration method also requires the addition of two motors and two metal corner reflectors, which increases the complexity of the construction exponentially. The present application does not require additional system debugging work, and reduces the test complexity and test cost.

[0128] Preferably, it can also be applied to micro-motion targets in different millimeter-wave frequency bands. It only needs to replace the receiving antenna, low-noise amplifier, down-conversion mixer, first up-conversion mixer, second up-conversion mixer, combiner, bandpass filter and transmitting antenna in the circuit with devices of the corresponding frequency band, thereby expanding to the required millimeter-wave frequency band. In order to adapt to different millimeter-wave frequency bands, the traditional mechanical vibration method needs to replace metal corner reflectors of different sizes, which increases the complexity of the structural design, and requires recalibration and recalibration after replacement, which increases the complexity of the test.

[0129] In the embodiment of the present application, by setting up an analog signal conditioning circuit, the limitations of system accuracy and service life brought by traditional mechanical vibrations are eliminated. Parameter configuration and information interaction can also be performed in conjunction with a host computer, a microcontroller, and input and output devices, thereby simulating micro-motion targets of different echo intensities and different distances, thereby improving the reliability and accuracy of radar detection.

[0130] It can be understood that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0131] The above embodiments are merely exemplary embodiments used to illustrate the principles of the embodiments of the present application, but the embodiments of the present application are not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made 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: A signal receiving unit, used for receiving a target signal; A down-conversion unit, configured to down-convert the target signal from a first frequency range to a second frequency range through a down-conversion mixer; an analog transmission unit, configured to allow the target signal down-converted to the second frequency range to pass 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; an up-conversion unit, comprising at least two up-conversion branches, each of which is provided with a digitally controlled attenuator for adjusting the signal strength of the target sub-signal, and an up-conversion mixer for up-converting the target sub-signal after adjusting the signal strength to the first frequency range; A signal transmitting unit, configured to combine the at least two target sub-signals up-converted to the first frequency range into a mixed signal, and send the mixed signal to the radar to be tested; The input frequencies of the local oscillator signals of the down-conversion mixer and each of the up-conversion mixers are derived from the output frequencies of corresponding phase-locked loops, and the reference frequencies of several phase-locked loops are derived from the same reference source.

2. The analog signal conditioning circuit according to claim 1, characterized in that: The phase-locked loop at least comprises a first phase-locked loop connected to the down-conversion mixer, and a second phase-locked loop and a third phase-locked loop connected to a plurality of the up-conversion 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 according to claim 2, characterized in that: The down-conversion unit further comprises a low noise amplifier connected to the signal receiving unit, a first input end of the down-conversion mixer is connected to the low noise amplifier, and a second input end of the down-conversion 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 down-conversion mixer, so that the down-conversion mixer down-converts the target signal from a first frequency range to a second frequency range.

4. The analog signal conditioning circuit according to claim 3, characterized in that: The down-conversion unit further comprises a filter connected to the output end of the down-conversion mixer, and a first amplifier connected to the filter; The filter is used to filter the target signal that is 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 according to 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 cable; The RF cable is connected to the down-conversion unit to simulate a target distance of a preset length, and the power divider is used to divide the target signal passing through the RF cable into at least a first target sub-signal and a second target sub-signal with equal power as the first target sub-signal.

6. The analog signal conditioning circuit according to claim 5, characterized in that: The up-conversion branch at least includes a first up-conversion branch for transmitting the first target sub-signal, and a second up-conversion branch for transmitting the second target sub-signal; The first up-conversion branch is provided with a first digitally controlled attenuator for adjusting the signal strength of the first target sub-signal, and a first up-conversion mixer for up-converting the first target sub-signal after adjusting the signal strength to the first frequency range; The second up-conversion branch is provided with a second digitally controlled attenuator for adjusting the signal strength of the second target sub-signal, and a second up-conversion mixer for up-converting the second target sub-signal after adjusting the signal strength to the first frequency range.

7. The analog signal conditioning circuit according to claim 6, characterized in that: A first input end of the first up-conversion mixer is connected to the first digitally controlled attenuator, and a second input end of the first up-conversion mixer is connected to the second phase-locked loop; The first input end of the second up-conversion mixer is connected to the second phase-locked loop, the second input end of the second up-conversion mixer is connected to the third phase-locked loop, and the output ends of the first up-conversion mixer and the second up-conversion mixer are both connected to the signal transmitting unit.

8. The analog signal conditioning circuit according to claim 6, characterized in that: The first up-conversion branch is further provided with a second amplifier connected to the first digitally controlled attenuator and the power divider, and the second up-conversion 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 according to claim 1, characterized in that: The signal transmitting unit comprises 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 the at least two target sub-signals that are up-converted to the first frequency range into one mixed signal, and the transmitting antenna is used to send the mixed signal to the radar to be tested.

10. The analog signal conditioning circuit according to claim 9, characterized in that: A bandpass filter is also provided between the combiner and the transmitting antenna, and the bandpass filter is used to filter out spurious signals in the mixed signal, so that the transmitting antenna sends the filtered mixed signal to the radar to be tested.

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

Images