Radar target simulation and multi-range simulation using PMCW radar

Abstract

The present invention relates to a method for testing a vehicle radar, comprising obtaining a binary phase code of a transmitter in a radar DUT, obtaining an expected field of view and an expected angular resolution of the transmitter to determine a target angle of a simulated radar target; calculating a far-field phase of a radar signal for each of the target angles using a binary phase state of a transmit array to determine a resulting phase symbol stream; calculating an excess round-trip time delay for each simulated delay between the radar DUT and the simulated radar target, and each setup delay between the radar DUT and each simulator receiver; time-shifting the resulting phase symbol stream by the excess round-trip time delay; subtracting the time-shifted resulting phase symbol stream from the resulting phase symbol stream to obtain a difference phase symbol stream; modulating a radar signal transmitted by the radar DUT using the difference phase symbol stream; and simulating an echo signal at the target angle in response to the modulated radar signal.

Description

Background Art

[0001] Millimeter wave (mmWave) automotive radar is a key technology for advanced driver assistance systems (ADAS) and planned autonomous driving systems. Millimeter waves are generated by oscillations at frequencies in the spectrum between 30 gigahertz (GHz) and 300 GHz. For example, millimeter wave automotive radar is used in ADAS to warn of front and rear collisions, thereby enabling adaptive cruise control and autonomous parking and ultimately autonomous driving on streets and highways. The advantage of millimeter wave automotive radar over other sensor systems is that it can operate in most types of weather and can operate in both light and darkness. The adaptability of millimeter wave automotive radar reduces costs to the extent that millimeter wave automotive radar can now be deployed in large quantities. Therefore, millimeter wave automotive radar is now widely used for long-range, medium-range and short-range environmental sensing in ADAS. In addition, it is possible that millimeter wave automotive radar systems will be widely used in autonomous driving systems currently under development.

[0002] Conventional automotive millimeter-wave radar systems typically have multiple radio frequency (RF) transmitters and multiple RF receivers, where the RF transmitters can be used to improve the spatial resolution of the radar or enable transmitter beam scanning. The actual driving environments in which automotive radars can be deployed may vary greatly, and many such driving environments may be relatively complex. For example, the actual driving environment may contain many objects, and some objects encountered in the actual driving environment have complex reflection, diffraction, and multiple reflection characteristics that affect the return signal. The direct consequence of not correctly sensing and / or interpreting the return signal may be the triggering of erroneous warnings or inappropriate reactions, or the failure to trigger warnings or reactions that should be triggered, which in turn may lead to a collision.

[0003] In recent years, developers testing autonomous vehicles in real-world driving environments have reported a series of accidents, highlighting the importance of thoroughly testing the vehicle's radar and onboard drive controllers. Road testing can be problematic and very expensive. So-called driverless road testing is permitted in only a few locations worldwide, though it is controversial where it is permitted. Almost all such locations require a human in the driver's seat to prevent the autonomous vehicle's artificial intelligence (AI) system from making serious errors. Furthermore, much of the early data was questionable because (safety) drivers often actively took the steering wheel at some point during critical performance periods, either out of instinct or boredom. Nowadays, a passenger often rides with the driver in the car to help monitor the driver's actions and record other observations.

[0004] To avoid such accidents, automotive radars can be tested in various driving scenarios. The test environment for automotive radars can include a scenario simulator that simulates the return signals from multiple objects or targets to different radar sensors or radar devices under test (DUT) on the vehicle (multi-target return signals) in a driving scenario. This makes it possible to simulate a wide variety of driving scenarios without the need for a safety driver or local government permission. Although single-target simulation is well established, multi-target simulation is still in its infancy. Most demonstrators today show up to three corner prism antennas sliding back and forth, each connected to an expensive arbitrary waveform generator (AWG). This cannot be extended to more targets due to the cost of the equipment and the dynamically changing angles of arrival (AoA) that represent driving scenarios, which quickly lead to problems with operating the corner prisms without mutual obstruction or even collisions between antennas.

[0005] Currently, frequency-modulated continuous wave (FMCW) radars make up almost 100 percent of the automotive radar market. However, phase-modulated continuous wave (PMCW) is expected to be the next (third) generation of automotive radar technology, offering perceived advantages in interference immunity and finer range resolution. Specifically, interference immunity is achieved through code orthogonality, similar to that found in phase-modulated code division multiple access (CDMA) technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The exemplary embodiments are best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that the various features are not necessarily drawn to scale. In fact, the dimensions may be arbitrarily increased or decreased for clarity of discussion. Where applicable and practical, the same reference numerals refer to the same elements.

[0007] Figure 1A is a simplified block diagram illustrating a system for testing vehicle radar according to a representative embodiment.

[0008] Figure 1B is a diagram showing a typical embodiment of the present invention. Figure 1A A simplified block diagram of a modulated reflectometer device (MRD) in a system for testing vehicle radar.

[0009] Figure 1C is a diagram showing a typical embodiment of the present invention. Figure 1A A simplified block diagram of a modulated reflectometer device (MRD) in a system for testing vehicle radar.

[0010] Figure 2A is a simplified flow chart illustrating a general method for simulating target range for a PMCW radar signal, according to a representative embodiment.

[0011] Figure 2Bis a simplified block diagram illustrating an apparatus for acquiring a quadrature binary phase code (phase code) of a PMCW radar signal for each of a plurality of radar transmitters of a device under test (DUT).

[0012] Figure 3 Determination of a reflected simulated radar signal from a simulated target after correction for phase differences is shown according to a representative embodiment.

[0013] Figure 4 is a graph showing simulator correlation results regarding delay as a function of azimuth angle relative to a simulation target, according to a representative embodiment.

[0014] Figure 5 is a graph illustrating a phase symbol stream of a PMCW signal having pulses subdivided into two substreams corresponding to simulated targets at different distances, according to a representative embodiment.

[0015] Figure 6A is a simplified block diagram illustrating an MRD including direct digital synthesis (DDS) according to a representative embodiment.

[0016] Figure 6B is a graph showing illustrative tone snapshots of a radar signal undergoing DDS processing according to a representative embodiment. DETAILED DESCRIPTION

[0017] In the following detailed description, for the purpose of explanation and not limitation, representative embodiments of the disclosure details are set forth to provide a comprehensive understanding of the embodiments according to the present teachings. Descriptions of known systems, equipment, materials, operating methods, and manufacturing methods may be omitted to avoid blurring the description of the representative embodiments. Nevertheless, systems, equipment, materials, and methods within the scope of knowledge of those of ordinary skill in the art are also within the scope of the present teachings and can be used according to the representative embodiments. It should be understood that the terms used herein are only used to describe specific embodiments and are not intended to be restrictive. The defined terms are appended to the technical and scientific meanings of the defined terms that are generally understood and accepted in the technical field of the present teachings.

[0018] It will be understood that although the terms first, second, third, etc. may be used to describe various elements or components in this article, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Therefore, without departing from the teachings of this disclosure, the first element or component discussed below may be referred to as the second element or component.

[0019] The terms used herein are only used to describe specific embodiments and are not intended to be restrictive. As used in this specification and the appended claims, the singular forms "a, an" and "the" of the terms are intended to include both singular and plural forms, unless the context clearly provides otherwise. In addition, when used in this specification, the terms "include" and / or "comprise" and / or similar terms clearly define the existence of the features, elements and / or parts, but do not exclude the existence or addition of one or more other features, elements, parts and / or their groups. As used herein, the term "and / or" includes any and all combinations of the items listed in one or more associations.

[0020] Unless otherwise specified, when an element or component is referred to as being “connected to,” “coupled to,” or “adjacent to” another element or component, it will be understood that the element or component may be directly connected or coupled to the other element or component, or that intervening elements or components may be present. In other words, these and similar terms encompass situations where one or more intermediate elements or components may be employed to connect two elements or components. However, when an element or component is referred to as being “directly connected to” another element or component, this only encompasses situations where the two elements or components are connected to each other without any intermediate or intervening elements or components.

[0021] The present disclosure is therefore intended to illustrate one or more of the advantages specifically noted below, through its various aspects, embodiments, and / or specific features or subcomponents. For purposes of explanation and not limitation, example embodiments disclosing specific details are set forth to provide a thorough understanding of embodiments according to the present teachings. However, other embodiments consistent with the present disclosure that depart from the specific details disclosed herein are still within the scope of the appended claims. In addition, descriptions of well-known devices and methods may be omitted so as not to obscure the description of the example embodiments. Such methods and devices are within the scope of the present disclosure.

[0022] According to various embodiments, a target simulation system is capable of simulating target return signals in response to simultaneous PMCW radar signal transmissions from multiple transmitters of a radar DUT. PMCW radars use CDMA technology to mitigate interference from other vehicles also deploying radars. Therefore, the different phase codes of the PMCW radar signal are orthogonal to each other, allowing for more focused signal processing to suppress interference. Phase codes can completely replace the FM chirp used in FMCW radars. In this case, CDMA itself performs the ranging function, and the IQ modulator of the FMCW radar system can be replaced with a binary phase modulator, using, for example, a unique phase code available from the radar DUT vendor. Typically, the simulated delay corresponding to the simulated radar target is determined by modulating a carrier signal with the difference between a set delay code waveform and a simulated delay code waveform. In this manner, the DUT receiver receives a code stream corresponding to the desired simulated delay. Furthermore, in the embodiments of the FMCW radar signal or PMCW radar signal disclosed herein, more than one target can be simulated per illuminator, assuming that these targets share the same angle of arrival (AoA) relative to the radar DUT.

[0023] Figure 1A is a simplified block diagram illustrating a system 100 for testing a vehicle radar according to a representative embodiment. As will be appreciated by those of ordinary skill in the art having the benefit of this disclosure, one possible vehicle radar is an automotive radar used in various capacities in current and emerging automotive applications. However, it is emphasized that the presently described system 100 for testing a vehicle radar is not limited to automotive radar systems and can be applied to other types of vehicles, including buses, motorcycles, electric bicycles (e.g., scooters), and other vehicles that can employ vehicle radar systems.

[0024] Reference Figure 1A , the system 100 is arranged to test a radar device under test (DUT) 102 and includes a plurality of re-illuminators 106. Each re-illuminator 106 includes at least one re-illuminator antenna 108 and at least one modulated reflectance device (MRD) 110. As described more fully herein, there is one re-illuminator for each simulated target. In an embodiment, in addition to the re-illuminators 106, the system 100 may further include a diffractive optical element (DOE), as described in U.S. Provisional Patent Application No. 62 / 889,267 filed by Gregory S. Lee on August 20, 2019, the entire contents of which are incorporated herein by reference. The system 100 is configured to receive a PMCW radar signal (or FMCW radar signal) from a radar DUT 102 having a plurality of radar transmitters and corresponding transmit antennas.

[0025] System 100 also includes a computer 112, which includes a controller 114. The controller 114 described herein may include a memory 116 for storing instructions and a combination of an illustrative processor 118 for executing instructions to implement the processing described herein. A database 120 may store information to be used for target simulation, including parameters of various predetermined scenarios and specific DUT 102, such as code and field of view (FOV). The controller 114 may be housed in or linked to a workstation, such as another component of the computer 112 or one or more computing devices, a display / monitor, and one or more input devices (e.g., keyboard, joystick, and mouse) in the form of an independent computing system, a client computer of a server system, a desktop, or a tablet computer. The term "controller" broadly encompasses all structural configurations of a dedicated motherboard or a dedicated integrated circuit for controlling the various principles described in this disclosure, as understood in the art of this disclosure and as exemplarily described in this disclosure. The structural configuration of a controller may include, but is not limited to, one or more processors, one or more computer-usable / computer-readable storage media, one or more operating systems, one or more application modules, one or more peripheral device controllers, one or more slots, and one or more ports.

[0026] In addition, although the computer 112 and / or controller 114 are shown as networked components, two such components can be integrated into a single system. For example, the computer 112 and / or controller 114 can be integrated with a display (not shown) and / or with the system 100. On the other hand, the networked components of the computer 112 and / or controller 114 can also be spatially distributed, such as by being distributed in different rooms or different buildings, in which case the networked components can be connected via a data connection. In yet another embodiment, one or more components of the components of the computer 112 and / or controller 114 are not connected to other components via a data connection, but rather manually provide input or output, such as through a memory stick or other form of memory. In yet another embodiment, the functions described herein can be performed based on the functions of the elements of the computer 112 and / or controller 114 but outside the system 100.

[0027] The computer 112 and / or the controller 114 may be implemented as a processing unit. In various embodiments, the processing unit may include one or more computer processors (e.g., processor 118), digital signal processors (DSPs), field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), or combinations thereof, using any combination of hardware, software, firmware, hard-wired logic circuitry, or combinations thereof. The computer 112 and / or the controller 114 may include its own processing memory (e.g., memory 116) to store computer readable code (e.g., software, software modules) capable of performing the various functions described herein. For example, the processing memory may store code that can be executed by the processing unit (e.g., a computer processor) to perform some or all aspects of the methods described herein (including those described below with reference to the accompanying drawings). Figure 2A The software instructions / computer-readable code for performing the various steps of the method described herein are generally executed to cause the processing unit of the computer 112 and / or the controller 114 to simulate the return signal reflected from the simulated radar target in response to the PMCW signal transmitted by the radar DUT 102. The memory (and database) as described herein can be RAM, ROM, flash memory, electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disk, removable disk, magnetic tape, compact disk read-only memory (CD-ROM), digital versatile disk (DVD), registers, hard disk, removable disk, magnetic tape, floppy disk, Blu-ray disc or universal serial bus (USB) drive, or any other form of storage medium known in the art that is tangible and non-transitory computer-readable storage medium (e.g., as compared to a transient propagating signal). Without departing from the scope of the present teachings, the memory can be volatile or non-volatile, secure and / or encrypted, unsecure and / or unencrypted.

[0028] Although the various components of system 100 are described in greater detail below in conjunction with representative embodiments, a brief description of the functionality of system 100 is currently presented.

[0029] In operation, radar DUT 102 emits a radar signal (illustratively, a millimeter-wave signal) that is focused on a corresponding one of antennas 108 of MRD 110, which, as described more fully below, are advantageously relatively high-gain antennas. For example, system 100 may include a diffractive optical element (DOE), such as described in the aforementioned U.S. Provisional Patent Application No. 62 / 889,267. The emitted radar signal is incident on a first side of the DOE, which diffracts the signal from radar DUT 102 to focus on a corresponding one of antennas 108. In this manner, the DOE diffracts the incident wave at a specific angle relative to a second side of the DOE, and each diffracted wave is focused on a corresponding one of antennas 108. Of course, system 100 may include other devices for focusing the radar signal on corresponding ones of antennas 108 of MRD 110 without departing from the scope of the present teachings. In particular, a respective focal point (alternatively, focus point) at each of antennas 108 represents a target simulated by system 100 .

[0030] Again, each radar signal is incident on a corresponding one of the antennas 108 of the re-illuminator 106. The radar signal incident on antenna 108 is provided to a corresponding one of the MRDs 110. As described more fully herein, pulse code modulation of the incident signal is implemented in each MRD 110 based on input from controller 114 and advantageously simulates the target's range from radar DUT 102, the target's velocity relative to radar DUT 102, or both. Furthermore, and again as described more fully herein, azimuth and elevation are simulated by antenna 108, which may illustratively be a mechanical gimbal, or a combination of a mechanical gimbal and electronic simulation. The re-illuminated signal provided by MRD 110 is incident on radar DUT 102. Computer 112 receives the signal from radar DUT 102 for further analysis of the radar DUT 102's accuracy.

[0031] Figure 1B Based on representative implementation plans Figure 1A Aspects of the MRD 110 described in conjunction with the representative embodiment may be common to the MRD and delay electronics described above, although they may not be repeated again.

[0032] The MRD 110 is connected to the re-irradiation antenna 108 and may therefore be one of the re-irradiation antennas described above. Of course, in practice, there may be more than one MRD 110, and therefore more than one re-irradiation antenna 108, in the system (e.g., Figure 1A). In certain representative embodiments, the re-illumination antenna 108 is a horn selected for the wavelength of the signal received from the radar DUT 102. The re-illumination antenna 108 can have variable gain and can be coupled to a beamforming element (such as a lens) to adjust the degrees of freedom of the AoA, as described above. A horn or similar antenna for the re-illumination antenna 108 is not required, and other types of antennas, such as a patch antenna or patch antenna array (described below), can be incorporated without departing from the scope of the present teachings.

[0033] MRD 110 includes a circulator 402 connected to a mixer 403. Mixer 403 is an in-phase (I) and quadrature (Q) mixer (IQ mixer) or an IQ modulator. For reasons described below, the mixer is advantageously a single-sideband (SSB) IQ mixer with standard 90° phasing of the RF signal, resulting in an output of an upper sideband (USB) or lower sideband (LSB), thereby rejecting the LSB or USB, respectively. Alternatively, IQ mixer 403 can be adapted for binary phase modulation (BPM), quadrature phase modulation (QPM), 8-phase modulation, 16-QAM, etc. As discussed below, the modulation is selected to provide a desired approximation of the difference phase symbol. In particular, the amplitude approximation can be performed by IQ mixer 403 using techniques within the knowledge of a person of ordinary skill in the art.

[0034] The output of IQ mixer 403 is provided to variable gain amplifier (VGA) 404, which includes a gain control input 405. As described above, gain control input 405 of VGA 404 is connected to computer 112. Specifically, VGA 404 enables appropriate simulation of the re-illumination signal received from DUT 102 at re-illumination antenna 108. For example, when a DOE is involved, as described above, the incident signal from radar DUT 102 on the DOE is split between multiple focal points at re-illumination antenna 108. As such, once diffracted by the DOE, the power of the signal is split, and thus the power of each radar signal diffracted to the multiple focal points at re-illumination antenna 108 is reduced compared to the output power of the radar signal from radar DUT 102. Furthermore, as described above, the portion of the signal diffracted from the focal points on the side of the DOE facing re-illumination antenna 108 (and therefore the power) depends on the orientation of re-illumination antenna 108 relative to the one or more focal points at re-illumination antenna 108. As such, the power of the signal incident on the re-illumination antenna 108 may not be sufficient to be re-emitted back to the radar DUT 102 and therefore used for accurate testing. Furthermore, the power of the re-illumination signal from the re-illumination antenna 108 is an indication of the simulated distance between the simulated target and the radar DUT 102. As such, the gain provided by the VGA 404 is selected at the gain control input 405 based on the power of the radar signal incident on the re-illumination antenna 108 and the desired simulated distance of the target being simulated.

[0035] In particular, power is used to simulate a consistent radar cross section (RCS). For example, the RCS can be stored in a lookup table in the database 120. To this end, for a given range r, it is known that the return signal is proportional to the RCS and reduces to 1 / r. 4 Vehicles are often quoted as 10 dBsm, which is a measure of area in radar, meaning 10 dB relative to one square meter (sm), or simply 10 square meters. Many objects have been tabulated (people, cyclists, buildings, etc.), and it has not been possible to calculate those objects using ray tracing techniques. Through this teaching, the focus is on providing the radar DUT 102 with a distance r (obeying the well-known 1 / r 4The return signal strength is commensurate with the acceptable value of the RCS of a particular object (radar attenuation law). According to a representative embodiment, the signal strength (and therefore power) is adjusted by adjusting the strength of the I / Q drive signals from the computer 112 to the MRD of each embodiment, where a weaker I / Q drive signal provides a relatively weaker simulated signal. In particular, in certain representative embodiments, the computer 112 pre-calculates a consistent return signal provided to a single focal point at the radar DUT 102, and the controller 114 then adjusts the strength of the I and Q drives to achieve that SSB strength. Alternatively, and advantageously, the gain of the VGA 404 can be adjusted to control the return SSB strength.

[0036] When the vehicle radar is an FMCW device, the MRD 110 is used to electronically simulate the range / speed. To do this, the FMCW radar system uses a chirped waveform whereby the correlation of the original transmit (Tx) waveform from the radar DUT 102 with the receive (Rx) echo waveform reveals the target range. For example, at a chirp rate of ±k sw In an upchirp / downchirp system (measured in Hz / second), a target at distance d and zero relative velocity relative to the host vehicle will induce a frequency shift (δf) given by equation (1), where c is the speed of light and the factor of 2 is due to the round-trip propagation of the signal from the radar DUT 102:

[0037] δf=–(±2k sw d / c) Equation (1)

[0038] The sign of the shift depends on which part of the waveform is being processed (upchirp vs. downchirp). In contrast, the Doppler shift due to relative velocity appears as a "common-mode" frequency shift; for example, a net upshift on both halves of the waveform indicates that the radar DUT is getting closer to the target. Correlation is performed in the DUT's IF / baseband processor; bandwidths of several MHz are typical.

[0039] The most commonly deployed FMCW variations use either repeated up-chirps or repeated down-chirs, but not both (with an intervening dead time). Thus, the range to the target is determined as in the previous paragraph, now without the sign issue. Relative velocity is determined by measuring the phase shift between successive frame IF correlation signals, where a frame is a term for one period of the waveform. In many FMCW radar applications, the frame repetition rate is typically several kHz.

[0040] A known method introduces the concept of receiving the transmitted signal from the radar DUT at one or more probe points and then applying balanced phase modulation to the received signal before returning the signal to the radar DUT. Because phase modulation is another form of frequency modulation, the balanced phase modulation of this known system causes double-sideband (DSB) modulation of the original signal, thereby suppressing the original swept carrier. Balanced phase modulation is relatively easy to implement because one can simply switch between turning on an open load and a short load. If the modulation frequency is δf*, and the time-correlated frequency of the original signal is f(t), then due to the relatively slow chirp rate, the time-correlated frequency of the return signal is f(t) ± δf*. Equation (2) is obtained from Equation (1) using the target distance d em Distance d from the setting su The setup distance is the physical distance between the radar DUT 102 and the antenna 108 of one of the re-illuminators 106 , which is derived instead of d:

[0041] δf*=2k sw (d em -d su ) / c Equation (2)

[0042] Due to DSB modulation, for the em,j Each intentionally created target j at a distance d em,j ±2d su,j Create a double false target at d su,j is the setup distance to probe j, where the sign of the “ghosting equation” depends on the sign of the chirp slope. The method herein also suppresses such ghost targets.

[0043] Once amplified / attenuated at circulator 402, MRD 110 provides an amplified / attenuated SSB signal that is returned to circulator 402 and re-emitted out of re-illumination antenna 108. Specifically, in the representative embodiment of SSB MRD 110, reducing the strength of the modulated I and Q drive signals will reduce the output tone strength and, therefore, the RCS. In practice, this approach likely cannot achieve more than 15dB to 20dB of dynamic range using modulated drive alone. However, VGA 404 makes up for the shortfall in achieving the desired RCS dynamic range, and variable gain of 10dB to 50dB can be readily achieved through a combination of variable attenuators and amplifier bias adjustments.

[0044] Figure 1C Based on representative implementation plans Figure 1AAspects of the MRD 110 described in conjunction with the representative embodiment may be common to the MRD and delay electronics described above, although they may not be repeated again.

[0045] The MRD 110 is connected to the re-irradiation antenna 108. Of course, in practice, there may be more than one MRD 110, and therefore more than one re-irradiation antenna 108, in the system (e.g., Figure 1A ). In certain representative embodiments, the re-illumination antenna 108 is a horn selected for the wavelength of the signal received from the radar DUT 102. The re-illumination antenna 108 can have variable gain and can be coupled to a beamforming element (such as a lens) to adjust the degrees of freedom of the AoA, as described above. A horn or similar antenna for the re-illumination antenna 108 is not required, and other types of antennas, such as a patch antenna or patch antenna array (described below), can be incorporated without departing from the scope of the present teachings.

[0046] MRD 110 comprises a circulator 402 connected to a binary switch 406 and thus provides only an in-phase (I) output, which is advantageously single-sideband for the reasons described above. Because IQ mixer 403 is replaced by a binary switch, amplitude modulation is performed. To this end, the binary switch provides an output of either "1" or "0". This results in jitter of 1 / 2 above and below the DC average value. As will be appreciated, compared to true binary phase modulation (using Figure 1B Compared to the IQ mixer 403), this has a 6dB worse sideband conversion efficiency and does not fully suppress the carrier. Figure 1C MRD 110 and Figure 1B The conversion efficiency deficit can be easily compensated by more gain from amplifier 404.

[0047] The output of binary switch 406 is provided to VGA 404, which includes a gain control input 405. As described above, gain control input 405 of VGA 404 is connected to computer 112. Specifically, VGA 404 enables appropriate simulation of the re-irradiation signal received from DUT 102 at re-irradiation antenna 108. For example, when a DOE is involved, as described above, the incident signal from radar DUT 102 on the DOE is split between multiple focal points at re-irradiation antenna 108. As such, once diffracted by the DOE, the power of the signal is split, and thus the power of each radar signal diffracted to the multiple focal points at re-irradiation antenna 108 is reduced compared to the output power of the radar signal from radar DUT 102. Furthermore, as described above, the portion of the signal diffracted from the focal points on the side of the DOE facing re-irradiation antenna 108 (and therefore the power) depends on the orientation of re-irradiation antenna 108 relative to the one or more focal points at re-irradiation antenna 108. As such, the power of the signal incident on the re-illumination antenna 108 may not be sufficient to be re-emitted back to the radar DUT 102 and therefore used for accurate testing. Furthermore, the power of the re-illumination signal from the re-illumination antenna 108 is an indication of the simulated distance between the simulated target and the radar DUT 102. As such, the gain provided by the VGA 404 is selected at the gain control input 405 based on the power of the radar signal incident on the re-illumination antenna 108 and the desired simulated distance of the target being simulated.

[0048] Figure 2A is a simplified flow chart illustrating a general method for simulating target range of a PMCW radar signal according to a representative embodiment. For example, the method can be implemented on the system 100 discussed above. In an embodiment, Figure 2A The operations indicated by blocks S211 through S217 are pre-calculated, meaning they are performed prior to field testing (e.g., actual operation) of the radar DUT 102. In contrast, the operations indicated by block S218 occur during field testing of the radar DUT 102, which includes active (field) modulation of the MRD 110. The results of the operations indicated by blocks S211 through S217 may be stored in the database 120, e.g., for access during field testing.

[0049] Reference Figure 2AIn block S211, the orthogonal binary phase code (phase code), also known as the binary phase symbol, of the PMCW radar signal of each of the multiple radar transmitters of DUT 102 is acquired. A PMCW radar signal is a carrier signal that is binary phase-modulated across the chirp bandwidth according to the phase code. Due to the phase encoding, each PMCW radar signal (and each corresponding radar transmitter of DUT 102) has a unique signature. DUT 102 can use the phase code to separate the individual target echo signal streams corresponding to the multiple radar transmitters. Therefore, acquiring the phase code enables pre-calculation. Since testing may be performed in collaboration with the DUT manufacturer, the phase code can be acquired from the DUT manufacturer prior to testing. For example, the phase code of the radar transmitter can be provided along with DUT 102 on a transportable computer-readable medium within the DUT itself, or separately using a portable memory device (such as a compact disc, DVD, USB drive, or any other form of storage media known in the art), or downloaded from a database server via a network. Alternatively, the phase code can be determined empirically, for example, by continuously turning off all but one radar transmitter in the DUT 102 and observing the PMCW radar signal of the one radar transmitter that is operating. Regardless of how it is obtained, the phase code can be stored in the database 120, for example, for later use.

[0050] In block S212, a desired field of view (FOV) and angular resolution are obtained for each of the plurality of radar transmitters of the radar DUT 102. Again, this information can be obtained from the DUT manufacturer or can be determined empirically and stored, for example, in the database 120. The target angle or angle of arrival to be tested is determined based on the desired FOV using a step size corresponding to the desired angular resolution. The FOV and angular resolution of the radar transmitter can be used to prepare a list of potential target angles for pre-test calculations.

[0051] Since PMCW is a binary phase, there are 2 #Tx There are four possible binary phase combinations (code states), where #Tx is the total number of transmit antennas in the radar DUT 102 corresponding to the radar transmitter. Thus, for example, when there are two transmit antennas (#Tx=2), there will be four possible code states. The code state indicates the number of degrees of freedom of the transmitted PMCW radar signal. Typically, in digital beamforming, the "phasing" of the antennas used to gather AoA information is done in baseband processing rather than at the DUT RF transmitter, and the two #TxThe code states are used for encoding and multiplexing / demultiplexing purposes. For this purpose, a single phase code may be sufficient to prevent interference, but as discussed above, having a separate phase code for each (radar transmitter) allows the radar DUT 102 to distinguish between its own transmit streams when performing multiple-input and multiple-output (MIMO) processing.

[0052] In block S213, the phase of the PMCW signal is calculated for the binary phase state of the transmit array at each target angle to determine a time sequence and a resulting phase symbol stream. That is, the 2 phase states for the DUT transmit array are determined for each target angle determined in block S212. #Tx The phase (and optionally the amplitude) of the transmitted PMCW radar signal for each of the code states is shown in Figure 1. The phase is angle-dependent in the far field (far-field phase). In particular, a first code state (180°, 180°, ... 180°) produces the same far-field wave as the opposite second code state (0°, 0°, ... 0°), but with a global 180° phase shift that is independent of the target azimuth and elevation. In fact, for each state, there is another state that is exactly 180° offset from it. Therefore, in an embodiment, only 2 phases can be performed for each angle. #Tx-1 unique calculation, and the other 2 can be determined by simply performing a global -180° phase shift of the calculated far-field phase distribution. #Tx-1 This is half the number of possible code states, which is typically greater than half the number of transmitters.

[0053] In block S214, at least the phase determined in block S213 is stored in memory as a resulting phase symbol stream. The resulting amplitude may also be stored, but this is optional since subsequent determinations do not depend on the amplitude. The resulting phase (and amplitude) may be stored, for example, in database 120.

[0054] In block S215, the excess round trip time delay (t 过量 This identifies the difference in round trip time delay between the resulting symbol stream being within the setup time delay and the resulting phase symbol stream being within the simulated time delay. Determining the excess round trip time delay with respect to the simulated target relies on the physical setup delay (d ) based on the actual distance between the radar DUT 102 and the MRD 110 corresponding to the simulated target. su ), and the expected simulated delay (d em ), as discussed above. Given this information, the excess round-trip time delay (t 过量 ), where c is the speed of light:

[0055] t过量 =2(d em -d su ) / c Equation (3)

[0056] In block S216, each resulting phase symbol stream is time-shifted by the corresponding excess round-trip time delay t determined in block S215. 过量 , and the time-shifted resulting phase symbol stream is subtracted from the unshifted resulting phase symbol stream determined in block S213 to provide a difference phase symbol stream, modulo 360 degrees. The difference phase symbol stream effectively provides a corrected version of the unshifted resulting phase symbol stream that appears to be reflected from the simulated target and the desired distance.

[0057] In block S217, the difference phase symbol stream is approximated by a positive number of bits, since, for example, using phase quantization, there is no cost-effective infinite phase accuracy. That is, in practice, the unshifted resulting phase symbol stream does not need to be corrected to an infinite number of bits. Therefore, a representative number of bits, such as 1, 2, or 3 bits, can be selected to approximate the difference phase symbol stream.

[0058] As mentioned above, in an embodiment, the operations indicated by blocks S211 to S217 are pre-calculated, and the operations indicated by block S218 are performed during field testing of radar DUT 102. Specifically, in block S218, the IQ mixer 403 of MRD 110 is driven by the approximate difference phase symbol stream determined in block S217 to provide an IQ modulation phase. The IQ modulation phase is added to the received resultant phase at the re-illumination antenna 108, and the resultant stream is approximately reconstructed at a later simulated delay time. Thus, the known PMWC radar signal (the resultant phase symbol stream) at the set point of MRD 110 is changed to indicate the PMWC radar signal at the simulated target point.

[0059] Figure 2B 2 is a simplified block diagram illustrating an apparatus 230 for acquiring a quadrature binary phase code (phase code) of a PMCW radar signal for each of a plurality of radar transmitters of a device under test (DUT). Various aspects of the apparatus 230 are the same as those of the various representative embodiments described herein, and details of these aspects may not be repeated.

[0060] As described above, the phase code at block S211 may be obtained directly from the DUT manufacturer. However, the apparatus 230 may be provided without providing the phase code. Specifically, a multi-channel BPSK receiver having multiple inputs is connected to a plurality of near-field probes 234_...234_n. Specifically, according to a representative embodiment, the DUT (not shown) has a plurality of transmit antennas 236_1...236_n, where n is an integer. The corresponding near-field probe 234_x is disposed in front of a corresponding one of the transmit antennas 236_x and is disposed between the antenna 236_x and the corresponding re-irradiation antenna 108 (see, e.g., Figure 1A Each of the plurality of near-field probes 234_...234_n provides a sample of the output of a corresponding one of the plurality of transmit antennas 236_1...236_n to the BPSK receiver 232 for collecting a phase code for each of the plurality of transmit antennas 236_1...236_n. Once the phase code is determined, the method 200 continues at block 212 as described above.

[0061] In particular, if the phase code is not too long (e.g., repeating every frame), a single probe can be scanned across n transmit subarrays, perhaps blocking n-1 unsampled subarrays at any spatial sampling location to improve discrimination. However, when the code repetition length extends over many frames, a parallel probing arrangement as shown must be used to ensure proper time alignment with the various Tx codes.

[0062] Figure 3 Determination of a reflected simulated radar signal from a simulated target after correction for phase differences is shown according to a representative embodiment.

[0063] Reference Figure 3 , the first line 301 shows the resulting vectors representing voltage phasors, which indicate the phase and amplitude of the round-trip delay over time for the actual and simulated delays of the resulting phase symbol stream of the PMWC signal at one far-field angle. The first set of three vectors reflects the set delay time of the resulting phase symbol stream measured at the MRD 110, and the second set of three vectors reflects the expected simulated delay time of the resulting phase symbol stream determined at the MRD 110. The set delay time is the round-trip delay inherent in the physical distance between the radar DUT 102 and the MRD 110. The simulated delay time is the round-trip delay that would result from the simulated distance between the radar DUT 102 and the location of the simulated target. The vectors in the first line 301 indicate the resulting phase symbol stream as a function of the far-field angle. The resulting vectors have different lengths (amplitudes), which may be caused by some code states causing constructive interference in a given angular direction and other code states causing destructive interference in the same direction.

[0064] The second line 302 shows a digital phase representation of the resulting phase symbol stream corresponding to the vector shown in the first line 301. The phases at the set delay times shown in the second line 302 are 47 degrees, 315 degrees, and 95 degrees, while the corresponding phases at the desired simulated delay times shown in the third line 303 are 83 degrees, 190 degrees, and 270 degrees. In particular, these phases are in the same direction as the vector, but are aligned with the simulated time delay rather than the set time delay.

[0065] The third line 303 shows the phase shifted from the excess round trip time delay, as seen above. Figure 2A As discussed in blocks S215 and S216 of FIG. A fourth line 304 shows a difference phase symbol stream modulo 360 degrees, which is determined by subtracting the resulting phase symbol stream from the time-shifted resulting phase symbol stream to obtain a difference phase symbol stream. The phase differences in fourth line 304 are 36 degrees, 235 degrees, and 175 degrees modulo 360, respectively. Regarding the 235-degree phase difference, the actual difference is -125 degrees, which translates to 235 degrees per modulo 360 operation.

[0066] The fifth line 305 shows an approximation of the difference phase symbol stream to be used in the IQ mixer to the difference phase symbol stream used for delay simulation, as described above with reference to FIG. Figure 2A As discussed in block S217 of FIG. In the depicted example, two bits are used for the approximation, but other bits may be incorporated without departing from the scope of the present teachings. Using two two-bit approximations, each of the phase differences is approximated by the nearest multiple of 90 degrees, such that a 36-degree phase difference is approximated by zero degrees, a 235-degree phase difference is approximated by 270 degrees, and a 175-degree phase difference is approximated by 180 degrees. Similarly, for example, if a three-bit approximation is used, each of the phase differences would be approximated by the nearest multiple of 45 degrees.

[0067] The sixth line 306 shows a vector representing a voltage phasor, which indicates the phase and amplitude of the approximate difference phase symbol stream over time, corrected for the phase difference. In particular, the arrows indicating the approximate difference phase symbol stream in the sixth line 306 point in substantially the same direction as the arrows indicating the resulting phase symbol stream in the first line 301. Therefore, the two phase symbol streams are well correlated in phase, although the amplitudes may not necessarily match because amplitude correction has not yet been attempted. In the depicted example, the returned amplitude may be too small (as in the case of the second arrow in the sixth line 306) or too large (as in the case of the third arrow in the sixth line 306). However, because PMCW uses correlation over the symbol values of the entire pulse (where a pulse is the duration of a radar cycle, equivalent to one chirp or one frame in FMCW), the amplitude mismatch is secondary to the already prioritized phase mismatch. For example, replacing 0.5 with 1.0 at one symbol time and 2.0 with 1.0 at a later symbol time (representing a change in magnitude) occurs only slightly indirectly compared to replacing -1.0 with 1.0 at one symbol time and 1.0 with 1.0 at a later symbol time (representing a change in phase). In an embodiment, the magnitude of the vectors may be renormalized so that the expected correlation strength matches the actual target's correlation strength, as will be discussed presently.

[0068] Figure 4 Figure 2 is a graph showing simulator correlation results for delay as a function of azimuth relative to a simulated target, according to a representative embodiment. In the depicted example, the PMCW pulses have a code length of 1000. Furthermore, the correlation results are for a typical automotive radar DUT configuration with four receive antennas spaced λ / 2 apart and three transmit antennas spaced the same as the number of receive antennas multiplied by λ / 2 (2λ in this example). This is a so-called "virtual array" design commonly found in digital beamforming radars.

[0069] Reference Figure 4 For illustration purposes, trace 441 indicates a phase modulation of 0 bits (i.e., no correlation), trace 442 indicates a phase modulation of 1 bit, trace 443 indicates a phase modulation of 2 bits, and trace 444 indicates an infinite phase modulation. With zero bits of phase modulation, the correlation with the simulated target distance decreases from unity to approximately This is a well-known principle of PMCW (and CDMA), as shown by trace 441. If phase modulation is performed by precise differential phase (no infinite phase modulation), as shown by trace 444, a maximum correlation of about 75 percent to almost 90 percent is achieved. The reason the correlation is not 100 percent is because no amplitude correction is performed, which, as discussed above, reduces complexity, cost, and power, among other advantages.

[0070] Phase modulation performed with one bit (as shown by trace 442) provides a correlation of about 50 percent to about 75 percent. The one-bit phase modulation can be, for example, bi-phase modulation (BPM) or binary phase shift keying (BPSK) modulation. Phase modulation performed with two bits (as shown by trace 443) provides a correlation of about 70 percent to about 80 percent. The two-bit phase modulation can be, for example, quadratic phase modulation (QPM) or quadrature phase shift keying (QPSK) modulation. Generally, two-bit phase modulation is a good compromise because it enables the use of the IQ mixer 403 of the MRD 110 with minimal driver complexity and achieves simulation fidelity that is almost the same as that achieved by unlimited-bit phase modulation as shown by trace 444.

[0071] In an embodiment, the gain of VGA 404 can be increased slightly using gain control 445 to bring the average correlation back to unity. While radar cross section (RCS) tends to vary over a larger range anyway, some target angles will see slightly more correlation and slightly less correlation. When a flatter correlation is desired compared to target angles, the gain of VGA 404 can be adjusted based on the target AoA. Using Figure 4 The appropriate curve in the , where the VGA gain is adjusted to compensate. For example, if there is a 1 dB dip at 36 degrees, the gain is increased by 1 dB for that angle. In addition, potential false targets are still suppressed by about Phase modulation of the radar is used, as discussed in U.S. Provisional Patent Application No. 62 / 889,267. This includes setting the distance. In the case of radar, the setting as the reflection point has been effectively replaced by a virtual reflector at the simulation point.

[0072] The above disclosure relates to determining the round-trip delay based on the simulated distance to a single simulated target for each MRD 110. However, one MRD 110 can be used to simulate multiple targets at the same target angle. That is, in an embodiment, the simulated distance is determined from the radar DUT 102 to each of the multiple simulated targets that share the same target angle (AoA) but are at different simulated distances.

[0073] Figure 5is a graph illustrating a phase symbol stream of a PMCW signal provided at a given target angle, the PMCW signal having pulses subdivided into two substreams corresponding to two simulated targets at different distances from a radar DUT, according to a representative embodiment. That is, the PMCW signal includes a phase symbol stream 511 having an exemplary pulse 515, the pulse subdivided into a first substream 516 modulated to simulate the distance to a first simulated target at the target angle, and a second substream 517 modulated to simulate the distance to a second simulated target at the same target angle, where the distance to the second simulated target is greater than the distance to the first simulated target.

[0074] PMWC radars (and FMCW radars) essentially use correlation to acquire the measurement data of interest. For example, correlation can be performed using a multidimensional Fast Fourier Transform (FFT) technique, but other techniques may also be incorporated herein without departing from the scope of the present teachings. For a single target simulation distance at a given target angle, correlation is code suppressed at all distances except the simulation distance. For example, to simulate multiple targets at two different distances but at the same target angle, unsuppressed correlation is allowed at these two distances. Specifically, for a PMCW radar, this is achieved by splitting each pulse 515 of the phase symbol stream 511 into an interleaved first substream 516 and second substream 517, and performing phase correction on the first substream 516 for the first simulated target and on the second substream 517 for the second simulated target.

[0075] like Figure 5 As shown, the duty cycles of the first substream 516 and the second substream 517 do not need to be equal, so unequal fractions of pulses 515 can be used to simulate different return signal strengths (e.g., RCS) of the return signal to the radar DUT. Again, the VGA gain can be increased to account for only partial correlation of one or both of the first and second simulated targets. The process can be generalized to more than two simulated targets at different distances without departing from the scope of the present teachings.

[0076] Figure 6A is a simplified block diagram illustrating an MRD including direct digital synthesis (DDS) according to a representative embodiment. Figure 6B is a graph showing illustrative tone snapshots of an FMCW signal undergoing DDS processing according to a representative embodiment.

[0077] Reference Figure 6A , MRD 610 and Figure 1BThe MRD 110 shown in FIG is essentially the same as that shown in FIG, with the addition of a DDS 409 for implementing multi-tone modulation. In the depicted embodiment, the DDS 409 provides multiple frequency offset sidebands from the chirped carrier, which are used to simulate multiple target ranges for targets at the same target angle. Thus, for example, when the chirp rate is k sw When the desired bias frequency δf* is 2k sw (d em -d su ) / c, according to the above equation (1). Therefore, for em1 d em2 ,…d emi Multiple targets at, single sideband (SSB) modulation is at δf1*=2k sw (d em1 -d su ) / c、δf2*=2k sw (d em2 -d su ) / c and so on.

[0078] Reference Figure 6B , vertically oriented arrows indicate discrete frequencies or tones. Tone 601 is the carrier of the suppressed FMCW radar signal (indicated by the dashed arrow). Tone 602 corresponds to the first sideband of the carrier used to simulate the first simulated target, and tone 603 corresponds to the second sideband of the carrier used to simulate the second simulated target. The time arrows indicate that the frequency tones 602 and 603 increase rigidly over time due to the upchirp of the carrier. The use of first and second sidebands reduces the correlation efficiency of the FMCW radar as the number of simulated targets increases. In particular, since the offset frequency is only a few MHz at most, the DDS 409 can be relatively inexpensive.

[0079] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

[0080] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude the inclusion of other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0081] Aspects of the present invention may be implemented as an apparatus, method, or computer program product. Thus, aspects of the present invention may take the form of a fully hardware implementation, a fully software implementation (including firmware, resident software, microcode, etc.), or an implementation combining software and hardware aspects, all of which may be collectively referred to herein as a "circuit," "module," or "system." Additionally, aspects of the present invention may take the form of a computer program product implemented in one or more computer-readable media having computer executable code implemented thereon.

[0082] The present invention includes the following embodiments:

[0083] 1. A method for simulating an echo signal reflected from a simulated radar target in response to a radar signal transmitted by a transmit array including a plurality of transmitters in a radar device under test (DUT), the method comprising:

[0084] Obtaining a desired field of view (FOV) and a desired angular resolution of the plurality of transmitters in the radar DUT to determine a target angle of the simulated radar target;

[0085] calculating a far-field phase of the radar signal for a binary phase state of the transmit array at each of the target angles to determine a resulting phase symbol stream;

[0086] calculating an excess round-trip time delay for each simulated delay between the radar DUT and each of the simulated radar targets and each setup delay between the physical distance between the radar DUT and each simulator receiver and the radar DUT;

[0087] time shifting the resulting phase symbol stream by the excess round-trip time delay;

[0088] subtracting the time-shifted resulting phase symbol stream from the resulting phase symbol stream to obtain a difference phase symbol stream;

[0089] modulating a radar signal transmitted by the radar DUT by a difference phase symbol stream for each of the target angles; and

[0090] The return signal is simulated at the target angle in response to the modulated radar signal.

[0091] 2. The method according to clause 1, further comprising:

[0092] The differential phase symbol stream is approximated, wherein modulating a radar signal transmitted by the radar DUT comprises modulating using the approximated differential phase symbol stream.

[0093] 3. The method of clause 2, wherein the difference phase symbol stream is approximated by two bits such that each of the phase differences is approximated by the nearest multiple of 90 degrees.

[0094] 4. The method of clause 2, wherein the difference phase symbol stream is approximated by three bits such that each of the phase differences is approximated by the nearest multiple of 45 degrees.

[0095] 5. The method of clause 1, wherein the radar signal is a phase modulated continuous wave (PMCW) radar signal.

[0096] 6. The method according to clause 5, further comprising:

[0097] Binary phase codes of the plurality of transmitters in the radar DUT are obtained, the binary phase codes enabling the plurality of transmitters to distinguish corresponding radar signals transmitted by the transmit array.

[0098] 7. The method according to clause 1, further comprising:

[0099] Prior to calculating the excess round trip time delay for each simulated delay and each setup delay, the far-field phase of the resulting phase symbol stream is stored.

[0100] 8. The method of clause 1, wherein the number of binary phase states of the transmit array is equal to two raised to the power of the number of transmitters in the transmit array.

[0101] 9. The method of clause 1, wherein each emulator receiver comprises a modulation reflection device (MRD).

[0102] 10. The method of clause 1, wherein the excess round trip time delay (t 过量 ) is calculated according to the following formula:

[0103] t 过量 =2(d em -d su ) / c,

[0104] Among them, d em is the simulation delay, d su is the setup delay, and c is the speed of light.

[0105] 11. The method of clause 1, wherein the number of transmitters is two and the number of binary phase states of the transmit array is four.

[0106] 12. A system for testing a vehicle radar including a radar device under test (DUT) comprising a transmit array, the transmit array including a plurality of transmitters, the system comprising:

[0107] a re-illumination element configured to receive radar signals transmitted by the plurality of transmitters and transmit simulated echo signals back to the radar DUT;

[0108] a controller configured to control the re-illumination element and perform a performance test on the vehicle radar, the controller comprising a processor and a memory storing instructions that, when executed by the processor, cause the processor to perform a method comprising:

[0109] Obtaining binary phase codes of the plurality of transmitters in the radar DUT;

[0110] Obtaining a desired field of view (FOV) and a desired angular resolution of the plurality of transmitters in the radar DUT to determine a target angle of the simulated radar target;

[0111] calculating a far-field phase of the radar signal for a binary phase state of the transmit array at each of the target angles to determine a resulting phase symbol stream;

[0112] calculating an excess round-trip time delay for each simulated delay between the radar DUT and each of the simulated radar targets and each setup delay between the physical distance between the radar DUT and each simulator receiver and the radar DUT;

[0113] time shifting the resulting phase symbol stream by the excess round-trip time delay;

[0114] subtracting the time-shifted resulting phase symbol stream from the resulting phase symbol stream to obtain a difference phase symbol stream;

[0115] causing a radar signal transmitted by the radar DUT to be modulated by a difference phase symbol stream for each of the target angles; and

[0116] The return signal is simulated at the target angle in response to the modulated radar signal.

[0117] 13. The system of clause 12, wherein the method performed by the processor further comprises:

[0118] The differential phase symbol stream is approximated, wherein modulating a radar signal transmitted by the radar DUT comprises modulating using the approximated differential phase symbol stream.

[0119] 14. The system of clause 12, further comprising:

[0120] A database stores far-field phases of the resulting phase symbol stream to be used by the processor to calculate the excess round-trip time delay for each simulated delay and each setup delay.

[0121] 15. The system of clause 12, wherein the radar signal is a phase modulated continuous wave (PMCW) radar signal.

[0122] 16. The system of clause 12, wherein the re-illumination element comprises at least one modulated reflective device (MRD), the at least one MRD comprising: an antenna; a circulator; an in-phase quadrature (IQ) mixer; and a variable gain amplifier (VGA).

[0123] 17. The system of clause 12, wherein the binary phase codes of the plurality of transmitters are obtained from a manufacturer of the radar DUT.

[0124] 18. A non-transitory computer-readable medium having software instructions stored thereon, the software instructions, when executed by a processor, causing the processor to perform a method for testing a vehicle radar of a radar device under test, the method comprising:

[0125] Obtaining binary phase codes of the plurality of transmitters in the radar DUT;

[0126] Obtaining a desired field of view (FOV) and a desired angular resolution of the plurality of transmitters in the radar DUT to determine a target angle of the simulated radar target;

[0127] calculating a far-field phase of the radar signal for a binary phase state of the transmit array at each of the target angles to determine a resulting phase symbol stream;

[0128] calculating an excess round-trip time delay for each simulated delay between the radar DUT and each of the simulated radar targets and each setup delay between the physical distance between the radar DUT and each simulator receiver and the radar DUT;

[0129] time shifting the resulting phase symbol stream by the excess round-trip time delay;

[0130] subtracting the time-shifted resulting phase symbol stream from the resulting phase symbol stream to obtain a difference phase symbol stream;

[0131] causing a radar signal transmitted by the radar DUT to be modulated by a difference phase symbol stream for each of the target angles; and

[0132] The return signal is simulated at the target angle in response to the modulated radar signal.

[0133] 19. The non-transitory computer-readable medium of clause 18, wherein the software instructions, when executed by the processor, further cause the processor to approximate the difference phase symbol stream, wherein a radar signal transmitted by the radar DUT is modulated using the approximated difference phase symbol stream.

[0134] 20. The non-transitory computer-readable medium of clause 19, wherein the excess round-trip time delay (t 过量 ) is calculated according to the following formula:

[0135] t 过量 =2(d em -d su ) / c,

[0136] Among them, d em is the simulation delay, d su is the setup delay, and c is the speed of light.

[0137] Although representative embodiments are disclosed herein, those skilled in the art will appreciate that many variations are possible based on the present teachings and are still within the scope of the appended claims. Therefore, the present invention is not to be limited except within the scope of the appended claims.

Claims

1. A method for simulating an echo signal reflected from a simulated radar target in response to a radar signal transmitted by a transmit array including a plurality of transmitters in a radar device under test (DUT), the method comprising: Obtaining a desired field of view (FOV) and a desired angular resolution of the plurality of transmitters in the DUT to determine a target angle of the simulated radar target; calculating a far-field phase of the radar signal for a binary phase state of the transmit array at each of the target angles to determine a resulting phase symbol stream; calculating an excess round-trip time delay for each simulated delay between the DUT and each of the simulated radar targets and each setup delay between the physical distance between the DUT and each simulator receiver and the DUT; time shifting the resulting phase symbol stream by the excess round-trip time delay; subtracting the time-shifted resulting phase symbol stream from the resulting phase symbol stream to obtain a difference phase symbol stream; modulating a radar signal transmitted by the DUT by a differential phase symbol stream for each of the target angles; and The return signal is simulated at the target angle in response to the modulated radar signal.

2. The method according to claim 1, further comprising: The differential phase symbol stream is approximated, wherein modulating the radar signal transmitted by the DUT comprises modulating using the approximated differential phase symbol stream.

3. The method according to claim 2, wherein: The difference phase symbol stream is approximated by two bits so that each of the phase differences is approximated by the nearest multiple of 90 degrees.

4. The method according to claim 2, wherein: The difference phase symbol stream is approximated by three bits so that each of the phase differences is approximated by the nearest multiple of 45 degrees.

5. The method according to claim 1, wherein The radar signal is a phase modulated continuous wave (PMCW) radar signal.

6. The method according to claim 5, further comprising: Binary phase codes of the plurality of transmitters in the DUT are obtained, the binary phase codes enabling the plurality of transmitters to distinguish corresponding radar signals transmitted by the transmit array.

7. The method according to claim 1, further comprising: Prior to calculating the excess round trip time delay for each simulated delay and each setup delay, the far-field phase of the resulting phase symbol stream is stored.

8. The method according to claim 1, wherein The number of binary phase states of the transmit array is equal to two raised to the power of the number of transmitters in the transmit array.

9. The method according to claim 1, wherein: Each emulator receiver comprises a modulation reflection device MRD.

10. The method according to claim 1, wherein The excess round trip time delay t 过量 It is calculated according to the following formula: t 过量 =2(d em -d su ) / c, Among them, d em is the simulation delay, d su is the setup delay, and c is the speed of light.

11. The method according to claim 1, wherein The number of transmitters is two, and the number of binary phase states of the transmit array is four.

12. A system for testing a vehicle radar including a radar device under test (DUT) comprising a transmit array, the transmit array comprising a plurality of transmitters, the system comprising: a re-illumination element configured to receive radar signals transmitted by the plurality of transmitters and transmit simulated echo signals back to the DUT; a controller configured to control the re-illumination element and perform a performance test on the vehicle radar, the controller comprising a processor and a memory storing instructions that, when executed by the processor, cause the processor to perform a method comprising: Obtaining binary phase codes of the plurality of transmitters in the DUT; Obtaining a desired field of view (FOV) and a desired angular resolution of the plurality of transmitters in the DUT to determine a target angle of a simulated radar target; calculating a far-field phase of the radar signal for a binary phase state of the transmit array at each of the target angles to determine a resulting phase symbol stream; calculating an excess round-trip time delay for each simulated delay between the DUT and each of the simulated radar targets and each setup delay between the physical distance between the DUT and each simulator receiver and the DUT; time shifting the resulting phase symbol stream by the excess round-trip time delay; subtracting the time-shifted resulting phase symbol stream from the resulting phase symbol stream to obtain a difference phase symbol stream; causing a radar signal transmitted by the DUT to be modulated by a differential phase symbol stream for each of the target angles; and The return signal is simulated at the target angle in response to the modulated radar signal.

13. The system of claim 12, the method performed by the processor further comprising: The differential phase symbol stream is approximated, wherein modulating the radar signal transmitted by the DUT comprises modulating using the approximated differential phase symbol stream.

14. The system of claim 12, further comprising: A database stores far-field phases of the resulting phase symbol stream to be used by the processor to calculate the excess round-trip time delay for each simulated delay and each setup delay.

15. The system according to claim 12, wherein: The radar signal is a phase modulated continuous wave (PMCW) radar signal.

16. The system of claim 12, wherein: The re-illumination element comprises at least one modulation reflective device (MRD), which comprises: an antenna; a circulator; an in-phase and quadrature IQ mixer; and a variable gain amplifier (VGA).

17. The system of claim 12, wherein: The binary phase codes of the plurality of transmitters are obtained from the manufacturer of the DUT.

18. A non-transitory computer-readable medium having software instructions stored thereon, the software instructions, when executed by a processor, causing the processor to perform a method for testing a vehicle radar of a radar device under test (DUT), the method comprising: Obtaining binary phase codes of multiple transmitters in the DUT; Obtaining a desired field of view (FOV) and a desired angular resolution of the plurality of transmitters in the DUT to determine a target angle of a simulated radar target; calculating a far-field phase of the radar signal for a binary phase state of the transmit array at each of the target angles to determine a resulting phase symbol stream; calculating an excess round-trip time delay for each simulated delay between the DUT and each of the simulated radar targets and each setup delay between the physical distance between the DUT and each simulator receiver and the DUT; time shifting the resulting phase symbol stream by the excess round-trip time delay; subtracting the time-shifted resulting phase symbol stream from the resulting phase symbol stream to obtain a difference phase symbol stream; causing a radar signal transmitted by the DUT to be modulated by a differential phase symbol stream for each of the target angles; and An echo signal is simulated at the target angle in response to the modulated radar signal.

19. The non-transitory computer-readable medium of claim 18, wherein: The software instructions, when executed by the processor, further cause the processor to approximate the difference phase symbol stream, wherein a radar signal transmitted by the DUT is modulated using the approximated difference phase symbol stream.

20. The non-transitory computer-readable medium of claim 19, wherein: The excess round trip time delay t 过量 It is calculated according to the following formula: t 过量 =2(d em -d su ) / c, Among them, d em is the simulation delay, d su is the setup delay, and c is the speed of light.

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