Method for over-the-air radar test system having modulation change detection

Abstract

To provide a test system required for verifying that an automotive radar system provides an intended function.SOLUTION: A radar modulation parameter detection system 420, 600 includes: an antenna 610 configured to receive a radar signal 602 from a radar under test (RUT) 601; a power detector 620 configured to determine a temporal power level profile of the received radar signal; and a processing circuit 640, the processing circuit 640 being configured to obtain a record including at least two different radar modulation schemes, and the radar modulation parameter detection system 420, 600 being configured to output a radar test system control signal determined on the basis of a current modulation scheme of the RUT 601.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates generally to automotive radar systems, and more particularly to testing methods, software, and apparatus for verifying the functionality of automotive radar systems. Aspects of this disclosure relate to methods, apparatus, and systems for detecting modulation changes by a radar transmitter under test and adapting one or more operations of a radar test system in response thereto. [Background technology]

[0002] Today's vehicles, such as cars and trucks, may use multiple radars to provide awareness of the vehicle's surroundings, which is used in applications such as adaptive cruise control, emergency braking, and other comfort and safety features. Radar systems measure characteristics such as distance, speed, and radar cross section (RCS) of one or more objects around the vehicle. Some more advanced radar systems also measure the azimuth and / or height of nearby objects. Objects may be stationary, such as road signs, or moving, such as other road users, including pedestrians, cyclists, and other vehicles.

[0003] It is necessary to verify that automotive radar systems provide the intended functionality. For this purpose, reliable and at the same time space-efficient and low-cost test systems are required. Summary of the Invention

[0004] A radar modulation parameter detection system is disclosed that can automatically detect which modulation parameters are used by a radar under test in an efficient and reliable manner. The system includes an antenna or at least one antenna port configured to receive radar signals from a radar under test (RUT) and a power detector configured to determine a temporal power level profile of the received radar signal (i.e., a profile of how radar signal power varies over time, such as when radar signal power starts and stops). The system also includes processing circuitry configured to obtain a recording including at least two different radar modulation schemes, each radar modulation scheme in the recording associated with a respective radar modulation parameter and a respective temporal power level profile data input. The processing circuitry is configured to identify a current modulation scheme used by the RUT from among the at least two different radar modulation schemes in the recording based on a comparison between the determined temporal power level profile of the received radar signal and the temporal power level profile data input in the recording. In this manner, the radar modulation parameter detection system can output a radar test system control signal determined based on the current modulation scheme of the RUT. Essentially, the radar modulation parameter detection system uses the temporal power profile of the radar transmission as a key to finding the correct input in the recording. Once the correct inputs are found during recording, the radar modulation parameters can be read out. This system is extremely reliable and cost-effective. Advanced versions can also predict future changes in radar modulation parameters, meaning the radar target simulator system can be preemptively reconfigured to adapt to future changes in radar modulation parameters. The radar modulation parameters determined in this manner can include any of the radar signal bandwidth, chirp length, chirp period, chirp slope, chirp center frequency, antenna configuration, antenna activation pattern, and antenna transmission pattern.The proposed radar modulation parameter detection system is versatile in that the records can contain any type of data, which can then be indexed using the temporal power level profile.

[0005] According to an embodiment, the record also describes a repeating time series of the modulation scheme of the RUT. In this case, the processing circuitry can be configured to determine a future modulation scheme of the RUT based on the identified current modulation scheme of the RUT and the repeating time series of the modulation scheme of the RUT, and the radar modulation parameter detection system is configured to output data indicative of the future modulation scheme of the RUT. In this manner, future changes in modulation parameters can be proactively determined, which is advantageous. One way to describe this type of repeating time series of modulation schemes is to add a pointer to the record entry that points to the next record entry in the time series. Thus, once the current modulation scheme is identified, for example, by its temporal power level profile, the next modulation scheme can be found in an efficient manner by following the pointer that indicates the next record entry. The repeating time series of the modulation scheme of the RUT can be determined based on a recursive analysis of a series of detected modulation schemes of the RUT, as described in more detail below.

[0006] According to an aspect, the processing circuitry is configured to detect the onset and / or cessation of transmission by the RUT based on the determined temporal power level profile of the received radar signal, and the radar modulation parameter detection system is configured to output a trigger signal indicative of the onset and / or cessation of transmission by the RUT. The trigger signal can be used, for example, to control various operations of the radar target simulator system. The trigger signal can also be used to control other auxiliary systems or collect data.

[0007] According to an aspect, the temporal power level profile of the received radar signal and the temporal power level profile data entry during the recording include a frame time period measured from the start of radar signal transmission to the cessation of radar signal transmission, the start and cessation of radar signal transmission being detected, for example, using a power threshold, and the frame time period being detected using a timer or clock. Using the frame time period in this manner has been shown to be a simple and reliable method for identifying the correct data entry during the recording and reliably deriving the current radar modulation parameters.

[0008] According to an aspect, the temporal power level profile of the received radar signal and the recorded temporal power level profile data input include at least one power threshold and a series of times at which the received radar signal exceeds the power threshold. This is a simple and reliable method for determining the temporal power profile data. Methods for robust configuration of the power threshold are also described in detail herein.

[0009] According to an aspect, the processing circuitry is configured to identify the current modulation scheme used by the RUT by using comparison metrics including a time period of the temporal power level profile of the received radar signal and / or a power level of the temporal power level profile of the received radar signal and / or an amplitude pattern of the temporal power level profile of the received radar signal. These comparison metrics tolerate the presence of noise and other impairments; i.e., the output of the power detector does not need to be perfect to identify the correct set of radar modulation parameters being recorded. System stability is thus enhanced, particularly in the presence of noise and other impairments. The comparison between the determined temporal power level profile of the received radar signal and the temporal power level profile data input being recorded preferably includes rising edge and / or falling edge threshold detection.

[0010] According to an aspect, the radar modulation parameter detection system also includes a modulation scheme detection subsystem configured to identify radar modulation parameters in the radar modulation scheme. The processing circuitry can be configured to populate the record in an automatic manner with the identified radar modulation parameters, which is advantageous if the radar modulation parameters used by the RUT are unknown or partially unknown.

[0011] According to an embodiment, the record includes at least two different sets of modulation schemes, each set including at least one modulation scheme, and the processing circuitry is configured to select which set to use based on an external input signal associated with the RUT. In this manner, external factors that influence the selection of a modulation scheme by the RUT can be taken into account. The external input signal can include, for example, any of a CAN, bus signal, Ethernet signal, or FlexRay bus signal, and the external input signal can indicate vehicle speed or yaw rate of vehicle 100.

[0012] According to an embodiment, the radar modulation parameter detection system is further configured to output a lock signal upon successful identification of the current modulation scheme of the RUT among at least two different radar modulation schemes, which lock signal can be used to identify valid radar test data and distinguish valid data from unreliable data obtained without lock, i.e., from unreliable data obtained using incorrect radar modulation parameters. In association with the above advantages, a method, a radar test system, a radar target emulator, and a computer program product are also disclosed herein.

[0013] In general, all terms used in the claims may be interpreted according to their ordinary meaning in the art unless specifically defined otherwise herein. Elements, devices, components, means, steps, and the like should be broadly interpreted as referring to at least one instance of the element, device, component, means, step, or the like, unless specifically stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless specifically stated otherwise. Further features and advantages of the present invention will become apparent upon studying the appended claims and the following description. Those skilled in the art will recognize that different features of the present invention can be combined to create embodiments other than those described below without departing from the scope of the present invention. [Brief explanation of the drawings]

[0014] A more particular description of aspects of the disclosure, cited by way of example, will now be set forth with reference to the accompanying drawings, in which:

[0015] [Figure 1] FIG. 1 shows a vehicle having an automotive radar system. [Figures 2A-2C] 2A-2C show schematic diagrams of some examples of radar waveform modulation schemes. [Figure 2D-2E] 2D-2E show schematic diagrams of some examples of radar waveform modulation schemes. [Figure 3] FIG. 3 provides some examples of modulation parameters for an exemplary radar waveform. [Figure 4] Figure 4 shows an example of a radar test system in use. [Figure 5] FIG. 5 shows modulation detection for a radar controlled by an external input signal. [Figure 6] FIG. 6 illustrates the detection and prediction of modulation parameters. [Figure 7A-7C] 7A-7C show some examples of temporal power level profiles. [Figure 8A-8B] 8A-8B show some examples of recordings that include radar modulation schemes. [Figure 9]FIG. 9 shows a schematic example of determining a temporal power level profile. [Figure 10] FIG. 10 illustrates the process for determining and verifying the threshold. [Figure 11] FIG. 11 shows a histogram of noise and signal samples for adjusting the initial threshold. [Figure 12] FIG. 12 illustrates a process for determining multiple thresholds. [Figure 13] FIG. 13 shows a schematic diagram of the frequency-based backscatter generation principle. [Figure 14] FIG. 14 shows a schematic diagram of the frequency-based backscatter generation principle. [Figure 15] FIG. 15 shows the time alignment between the mixer IF signal and the change in modulation scheme. [Figure 16] FIG. 16 illustrates schematically an exemplary method for testing and evaluating the response of an automotive radar system. [Figure 17] FIG. 17 is a schematic diagram of an exemplary computer system. [Figure 18] FIG. 18 illustrates an exemplary computer program product. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present disclosure will be described in more detail below with reference to the accompanying drawings, in which exemplary embodiments are shown. However, this disclosure may be embodied in many different forms and should not be construed as being limited to the embodiments set forth below. Rather, these embodiments are provided for the sake of thoroughness and completeness. Like reference words refer to like elements throughout the specification. The aspects set forth below represent the necessary information to enable one skilled in the art to practice this disclosure.

[0017] Automotive radars are used to enhance vehicle safety and comfort. They provide an accurate awareness of the vehicle's surroundings, which is used by safety features for life-saving decisions. Radars can measure the range, speed, angle (both azimuth and elevation), and RCS (radar cross section) of objects in the environment around the vehicle. Objects can be stationary (such as road signs and other traffic infrastructure) or moving (such as other road users). Radars send radio waves into the environment using one or more transmitter (TX) antennas. The transmitted signals are often set at high frequencies around 24 GHz or 77 GHz. The radar signals interact with one or more objects in the environment, and the echo signals (often referred to as radar signal backscatter) are received by the radar receiver (RX) antenna. The received signals are processed by the radar after downconversion and analog-to-digital conversion. When processing the received signals, signals from all receiver channels are processed and compared to estimate the range, speed, RCS, and angle of the target relative to the radar transmitter.

[0018] Radar is expected to provide high-quality data, however, like most sensors, radar has physical and technical limitations that impair its performance.

[0019] To be able to evaluate, test, and verify the performance of automotive radars, it is necessary to adequately test them in scenarios that are as close to reality as possible. Using radar target simulator (RTS) technology, target recognition can be virtually generated for the radar under test (RUT) over the air (OTA). RTS systems are typically active devices that operate in or near the same frequency band as the radar and are typically housed in an anechoic chamber. Most RTS systems for automotive radars create a virtual target distance recognition by receiving the radar signal and delaying it according to the expected distance. Another type of RTS system operates in the frequency domain; instead of delaying the radar signal, they apply a frequency shift that represents the delay to the radar transmission signal. Such RTS technology requires information about the radar signal modulation to accurately create a target frequency recognition for the radar under test (RUT).

[0020] An example of a frequency domain RTS system is described in WO2017 / 069695A1. At least some aspects of the technology disclosed herein are applicable in this type of RTS and may find use in other radar testing applications, as described in more detail below.

[0021] Automotive radars are used in a number of safety applications with different requirements. A radar system may be required to detect targets at greater distances in some applications, such as high-speed driving, while the same radar system may need to measure target range or speed at shorter distances with higher resolution when used in other applications, such as low-speed driving. The versatile functionality of such radars requires different modulation parameters; that is, radar systems emit different types of waveforms depending on the operating scenario.

[0022] Frequency-modulated continuous wave (FMCW) radar signals represent a well-known type of radar signaling used by many automotive radars. FMCW signals include multiple frequency sweeps, or chirps, typically grouped into frames, with each frame being a transmission with a well-defined start and pause in transmission. FMCW signals can be adapted to have various bandwidths, frequency sweep durations or chirp lengths, sweep or chirp periods, chirp slopes, number of sweeps per frame, chirp center frequencies, etc., depending on the operational scenario and conditions placed on the radar system. Some radar systems also use different antenna configurations or antenna beam patterns to illuminate long- and short-range targets, as shown in FIG. 1. The configuration parameters of radar transmissions will be referred to herein as radar modulation parameters. Consequently, bandwidth, frequency sweep duration or chirp length, sweep period or chirp period, chirp slope, number of chirps per frame, chirp center frequency, antenna configuration, transmit antenna activation, and transmit pattern are all examples of radar modulation parameters. FIG. 3 shows some examples of radar modulation parameters.

[0023] Automotive radar systems sometimes use several different radar modulation parameters to improve detection accuracy and reliability. Several sweep parameters can be used in FMCW-based systems, for example, within a frame or in different frames. Different antennas can also be used within a frame in a pattern; for example, a first transmit antenna can be active only during the first chirp transmission, and a second transmit antenna can be active only during the second chirp transmission. Switching between transmit antennas can be done in a repeating pattern within a frame or between frames.

[0024] Some examples of radar transmit waveforms are given in Figures 2A-E. Each waveform is described by a corresponding set of radar modulation parameters plotted using a frequency-time graph.

[0025] Figure 2A shows an example of an FMCW waveform containing two different frames of chirps with the same bandwidth but different chirp slopes, lengths, and periods. The transmit antennas have a transmit pattern where the first transmit antenna is active during chirps 1, 3, 5, and the second transmit antenna is active during chirps 2, 4, 6, and so on.

[0026] FIG. 2B shows another example of an FMCW waveform in which the center frequency is shifted between each two chirps.

[0027] 2C shows two FMCW frames with different bandwidths, different chirp slopes, and different chirp periods, which can be relevant, for example, for long-range and short-range detection, where larger bandwidths are needed for high-resolution detection by radar at short ranges.

[0028] Figure 2D shows the modulation characteristics of an FMCW waveform that includes a frame with two long chirps, commonly referred to as slow chirps, followed by a frame of a short chirp known as a fast chirp, with each frame transmitted by a different set of transmit antennas.

[0029] FIG. 2E shows an FMCW waveform with a variable center frequency within a frame.

[0030] FIG. 1 shows a vehicle 100 with a front radar 110 and multiple corner radars 120. The front radar 110 is configured to generate a short-range beam 140 and a long-range beam 150, which have different detection characteristics and exhibit different radar modulation parameters. A target (in this case, a pedestrian 130) is detected by the short-range beam 140, but not by the long-range beam 150, in this example. As a result, the RTS should ideally generate a return signal only when the short-range beam 140 is used, and should not generate a return signal when the long-range beam 150 is used. The objective of the system disclosed herein is not only to detect when a change in radar modulation parameters occurs, but also to predict what such a change will be and to associate the correct set of radar modulation parameters with the detection of a change in radar operation.

[0031] For a type of radar target simulator (RTS) known as a frequency-domain (modulation-based) RTS, the modulation scheme and parameters of the radar under test (RUT) must be known because the simulated target is represented using a target frequency signature that depends on radar modulation parameters such as FMCW chirp information (see Figure 3).

[0032] FIG. 13 shows an example of how a frequency-domain RTS can emulate a target that causes reflected radar backscatter with a delay T (seconds), as shown in graph 1300. It is desirable to emulate backscatter with a delay T. This can be achieved using a design such as that in schematic 1410 shown in FIG. 14. A receive antenna 200 receives the transmitted radar signal from the RUT, whereby optional amplification 202 is applied. A digital signal processor (DSP) determines a target signature to be applied to the received signal to emulate a target such as the target with delay T. The target signature is input to a mixer 204, which adjusts the frequency of the received radar signal. This target signature is an approximation of the frequency difference between the radar transmitted signal and what would be observed if that signal were reflected by a target with delay T.

[0033] In this way, once the radar modulation parameters are known, the frequency domain RTS can calculate the frequency signature of the simulated target. However, any change in the radar modulation parameters will cause a change in the frequency representation of the target, i.e., the input to mixer 204 to make the target appear at the correct range (and correct speed and / or angle). Consider, for example, the case in graph 1300 with a higher slope chirp, which would result in a higher frequency IF signal input to the mixer to emulate the same target at delay T.

[0034] Therefore, for radars with varying modulation parameters, the RTS preferably adapts the calculation of the frequency signature applied to the mixer depending on which modulation parameters the radar is currently using. Both the detection of changes in the radar modulation and the adaptation of the target frequency signature should occur in real time during the test.

[0035] This is shown in FIG. 15, where the RTS has two sets of modulation parameters, which can also be referred to as "modulation schemes" (Scheme A and Scheme B). The RTS switches between them in a repeating pattern. The input to the mixer also switches between two frequency signatures in time alignment with the modulation changes of the RUT. Thus, when the RUT changes modulation schemes to generate the near and far beams described in connection with FIG. 1, for example, the emulated target will be at the same range, speed, and / or angle.

[0036] Most automotive radars vary their modulation in a pattern. Therefore, the modulation changes are periodic in some way. According to certain aspects of the present disclosure, modulation parameter changes are predicted based on observation of the current modulation parameters (modulation scheme). With prior knowledge of the radar modulation pattern and the current modulation parameters, the next modulation parameters can be predicted. This prediction is used by the RTS to generate the desired frequency signature of a simulated target in real time. FIG. 4 shows an example RTS system 400 during testing of a RUT. Radar modulation parameters, as described above, are required for signal generation in a frequency-based RTS system. Signal generation includes, for example, generating an input signal to the mixer 204 described in connection with FIG. 14.

[0037] This information can be provided by the radar designer / manufacturer, according to a first example, or it can be obtained by using a spectrum analyzer with transient measurement capabilities (i.e., a measurement device such as an oscilloscope or spectrum analyzer with the ability to perform time-frequency measurements of high-frequency signals).

[0038] In this disclosure, a third example of measuring radar modulation parameters is provided. Radar signal measurements are here performed in an over-the-air configuration, as shown in Figure 5. This method can be used in a separate system for analyzing radar modulation, or it can be integrated with the RTS as a subsystem that provides radar parameters during the initial stages of RTS operation.

[0039] Referring to FIG. 5, the RUT should be placed in front of this signal measurement system 500, which includes the following elements: an antenna 510 in the frequency band of the RUT for receiving the signal emitted by the radar; an amplifier 520 for optionally amplifying the signal received from the radar; a mixer 530 for downconverting the radar RF frequency to baseband or IF; a frequency synthesizer 540 for generating a center frequency in the mixer; Analog-to-Digital Converter (ADC) 550, which converts the downconverted radar signal to digital; A digital signal processor (DSP) 560 that processes the radar signal to extract radar modulation parameters such as modulation bandwidth, chirp slope, chirp time, and chirp period.

[0040] The DSP unit 560 executes algorithms for processing the signals received from the RUT. These algorithms use time-spectral analysis of the received signals, such as a spectrogram or wavelet transform, to obtain the time evolution of the radar signal's spectrum. A spectrogram is a 3D plane where the x-axis is time, the y-axis is frequency, and the z-axis is magnitude / power. A radar signal appears as a "sawtooth" shaped waveform in the time-frequency plane, corresponding to a train of chirps, e.g., for FMCW radar. The range of the signal in the frequency domain reflects the bandwidth of the radar modulation. The periodicity of the chirps in the "sawtooth" curve can be used, for example, to extract the chirp period. The slope of the teeth in the "sawtooth" waveform is also a measure of the chirp slope.

[0041] Observing modulation parameters over successive frames makes it possible to identify whether the modulation parameter changes repeat in a pattern, and if so, to identify that pattern, i.e., a repeating time sequence of modulation schemes. For example, if the third frame of a chirp has the same parameters (e.g., slope, chirp period, etc.) as the first, and the fourth frame is similar to the second measured frame, and this sequence repeats, then the radar signal of the RUT can be assumed to follow a pattern involving two frame types or two alternating modulation schemes.

[0042] Some automotive radars vary their modulation depending on the ego-vehicle speed or yaw rate. In this case, the RUT can be triggered by a message on its communication bus (CAN, Ethernet, FlexRay, etc.), so that the RUT's modulation parameters change due to the ego-vehicle's movement while the RUT is measuring. Here, a different set of modulation schemes and their patterns is identified for each case where the modulation varies with ego-vehicle speed. For example, the RUT might use one set of three modulation schemes for ego-vehicle speeds below 60 kph and another set of four modulation schemes when the vehicle is driven above 60 kph. All sets of modulation schemes and patterns are saved in the record and used by the RTS to switch between modulation schemes when testing the RUT.

[0043] The modulation parameter detection system 420 in FIG. 4 identifies the current radar modulation parameters of the RUT and also predicts future modulation parameters (i.e., the RUT's next modulation scheme in time). This is done in real time based on previously known / measured modulation patterns and modulation parameters in the recordings. As in FIG. 4, the system works in conjunction with the frequency-based RTS 430 to generate an appropriate frequency signature of the target, which adapts according to the radar modulation parameters as they vary over time. Thus, the modulation parameter detection system provides timing of modulation parameter changes in the form of a trigger signal and an indication of the current or future modulation scheme from the recordings.

[0044] 6 shows a schematic of a radar modulation parameter detection system that receives radar signals over the air and detects radar parameters currently being used by the RUT. The system may also output data indicative of the RUT's future modulation schemes to be emitted at later locations in time.

[0045] The system consists of the following hardware components: an antenna 610 in the frequency band of the RUT; an RF power detector 620 in the same frequency band as the radar signal; ADC630 to convert the detector signal to digital; DSP 640 includes processing circuitry for processing the radar signal received through the RF power detector.

[0046] Algorithms executing in DSP 640 enable the modulation change detection system to provide information about when the next state in the modulation pattern begins and / or when the current state in the modulation pattern ends, and which modulation parameters correspond to the current and / or future states, e.g., which frame type is next. The system does this by determining a temporal power level profile of the received radar signal based on the output from power detector 620 and using this power level profile to find the correct entry in the record for the different modulation schemes associated with the RUT (i.e., the modulation scheme of the RUT). Each entry in the record is associated with a predetermined temporal power level profile comprising a frame duration, a chirp length pattern, a chirp period pattern, an average power level, a power level transition pattern, etc. The processing circuitry of the DSP can thus identify the current modulation scheme of the RUT 601 from among at least two different radar modulation schemes in the record based on a comparison between the determined temporal power level profile of the received radar signal and the temporal power level profile data entries in the record.

[0047] 7A shows a first example in which one modulation scheme has a temporal power level profile over time periods T1 through T4, and another modulation scheme has a temporal power level profile over time periods T2 through T3. The two schemes can be distinguished from each other in this case based on the frame period, which is then used to index into the recording to find the modulation parameters for each scheme. Thus, the system uses the temporal power level profile of the radar signal transmitted by the RUT to determine the modulation parameters used by the RUT in an efficient manner with very low latency.

[0048] Figure 7B shows an example where two modulation schemes have the same frame duration and therefore cannot be distinguished using frame duration alone. In this case, other aspects of the temporal power level profile can be used to index into the recording to find the correct set of modulation parameters. In the example of Figure 7B, the average power of the radar signal is used instead of the frame duration.

[0049] The temporal power level profile may also include multiple thresholds to distinguish the presence of each modulation scheme and associated crossing times, as shown in Figure 7C. This may be due to the activity of the transmit antennas of the RUT. Because these transmit antennas are differently positioned with respect to the antenna 610 connected to the detector 620, different levels may appear in the power level profile of the signal received from each alternate antenna, for example.

[0050] The power level profile may include any number of data items related to the output of a power detector in combination with a timer or clock, such as the integral over the power level, the peak power level, and the total radar signal energy obtained as the power level variation over the frame period.

[0051] Each entry in the record includes modulation parameters and can be identified using a temporal power level profile determined based on the output of power detector 620. The record can also describe a repeating time sequence of modulation schemes used by RUT 601. That is, the record entries can be connected to form a state machine as shown in Figures 8A and 8B. In this case, the processing circuitry of DSP 640 can be configured to determine future modulation schemes for RUT 601 based on the identified current modulation scheme of RUT 601 and the repeating (time) sequence of modulation schemes.

[0052] 8B shows an example of modulation schemes of the RUT that can correspond to different ego speeds. In this case, either set is used by the radar depending on the ego speed. The radar modulation parameter detection system uses a record with all sets of modulation schemes and compares the power level profile of the received radar signal with the temporal power level profiles of all data entries in the record to identify the current modulation scheme of the RUT and therefore which ego speed mode A or B the radar is in.

[0053] Alternatively, an external signal corresponding to the vehicle speed can, for example, limit the recording to a set of modulation types, so that the radar modulation parameter detection system compares only the selected set with the temporal power level profile of the received radar signal.

[0054] If the state machine is more complex than a simple repeating pattern, it may be required to observe multiple modulation scheme changes to locate the correct position in the state machine, i.e., in the time series of modulation schemes. One way to solve this problem is to form multiple hypotheses for each possible starting state in the state machine, and discard those hypotheses that cannot be true over time as more currently used modulation schemes are identified.

[0055] FIG. 9 illustrates a system 900 for determining the frame start and end triggers, frame length from the temporal power level profile of the received signal, and corresponding modulation scheme from the input being recorded, as an example of the above.

[0056] The algorithm includes at least the following steps: 1. A threshold is found to detect where a radar signal is present as opposed to where no radar signal is present (ie, where there is only noise between two frames, for example). 2. The detector output is compared to a threshold to find where the radar signal begins and / or ends based on the corresponding rising or falling edges. 3. A trigger signal is reported indicating the start of a frame / chirp by looking for a rising edge (from absence to presence of radar signal). 4. A trigger signal is reported indicating the end of a frame / chirp by looking for a falling edge (from the presence of a radar signal to its absence). The falling edge for the end of a frame can only be found after a certain time, i.e., the frame length, has elapsed. 5. The length of the current frame is found by comparing the time difference between the rising and falling edges corresponding to the start and end of the frame respectively. 6. The current chirp length is found from the chirp rising and falling edges. 7. The current chirp period is found from two consecutive chirp rising edges. 8. The frame length, chirp length, or chirp period of the current frame is compared to the recorded temporal power delay profile data input or modulation parameters (which are shown here as look-up tables (LUTs)) to identify the current state of the radar modulation pattern. Using the modulation pattern, the system can predict the next expected modulation parameters. 9. The following modulation parameters (modulation method) and trigger (synchronization signal) are sent to the RTS and used to generate a target signature corresponding to the radar modulation parameters. 10. If the vehicle speed changes the radar modulation during the test, the modulation change detection system will identify it using the same algorithm and predict the next modulation parameters based on the radar modulation pattern corresponding to the new vehicle speed.

[0057] A threshold is required to identify whether a radar signal is present or not, i.e., to determine the characteristics of the temporal power level profile. Having a good threshold is key for the modulation change detection algorithm to function properly. The antenna detector placement may not be sufficient for the radar power to be received by the system. In this case, a good threshold cannot be found. Finding a reliable threshold is possible given a good signal-to-noise ratio (SNR). The SNR is significantly affected by the placement of the detector antenna. This can be identified by looking at the threshold, as explained below.

[0058] In this invention, we propose an algorithm that uses statistical information from one or more detector signals to find the best possible threshold and verify whether the SNR is good enough for the modulation change detection algorithm to function fully. Figures 10 and 11 both show examples of how threshold configurations can be verified. 1. The digital signal processor receives samples of the detector signal coming from the ADC, such as the temporal power level profile mentioned above. The number of samples acquired (i.e. the period of this signal) is arranged so that all modulation patterns and interframe intervals (noise) occur several times, in order to have better statistics. 2. A histogram of the signal levels across all acquired samples is created. This histogram provides an empirical estimate of the distribution of radar signal and noise magnitudes, which may appear as two or more distinct peaks with a valley in between, depending on how the signal and noise levels are distinguished. More than two peaks in this distribution of samples can be due, for example, to frames from different transmit antennas, or different center frequencies received by the detector at different signal strength levels. The idea is to find the valley as the threshold. 3. The threshold level is where there is a zero crossing in the derivative of the histogram. 4. If there are no direct zero crossings, one can find the points in the derivative of the histogram where a positive value appears next to a negative value. A threshold can then be achieved by taking the average of these two points as the potential zero crossing point. The Early Raid Gate method can also be used to set the threshold. 5. From this initial threshold, a percentile of the left tail of the signal distribution and a percentile of the right tail of the noise-only distribution identify an interval. This interval is a measure of how good the SNR is. If the length of this interval is very small, it means that the signal and noise levels are not well distinguished. The signal-to-noise ratio determined in this way may not be considered sufficient for the modulation detection algorithm to operate at the initial threshold. Here, a change in configuration, for example in the position of the detector antenna, may help alleviate the problem, and repeating this process may lead to a better SNR for finding the threshold. 6. If the SRN is deemed sufficient to improve the initial threshold, the mean value between the two percentiles of the last step is used as the new threshold.

[0059] In summary, aspects of the present teachings relate to a radar modulation parameter detection system 400 in which a temporal power level profile is determined based, at least in part, on a comparison between the output of a power detector 62 and a threshold, as shown in FIGS. 10 and 11 and as described above. The processing circuitry 640 can be configured to determine the threshold based, for example, on a histogram of output samples from the power detector. According to certain aspects, the processing circuitry 640 is also configured to determine a signal-to-noise (SNR) ratio based on the histogram. The system can issue a notification if the SNR is too low so that mitigating action can be taken to improve the SNR. The system can also be configured to display the SNR during testing and / or record the SNR during testing to facilitate further analysis of the data.

[0060] If a radar has a varying bandwidth, center frequency, or transmit antenna, such changes will manifest as a fluctuation in the level of the detector's output signal. For example, radar signals coming from different transmit antennas of the RUT will be received at the detector with different strengths. Similarly, a change in center frequency will result in different levels in the detector's output signal. Thus, such changes will be reflected in the temporal power level profile of the radar signal received by the detector. These different levels in the detector's output signal will produce multiple valleys and peaks in the histogram of the detector's output signal. Here, a modulation change detection system can identify different types of frames by using more than one threshold. If such changes occur within a frame, it is possible to use a single threshold to identify the start of the frame and, with knowledge of the change pattern, predict the time when a change in center frequency or a switch between RUT transmit antennas will occur.

[0061] The threshold finding algorithm described above can be used to find multiple thresholds. In such a case, instead of finding one valley by looking for a zero crossing of the derivative of the histogram of the detector's output, it is necessary to find n-1 zero crossings, where n is the number of frames of different types in the overall radar modulation.

[0062] In the case of radars with multiple transmit antennas, they may switch between them. If a detector antenna is placed in front of the radar, signals from all of the radar's transmit antennas may not be received well enough. This can be addressed by using two or more detectors with their detector antennas geometrically spaced in front of the RUT transmit antenna. The combination of detector outputs can be used in various ways to improve threshold finding or modulation change detection algorithms. For example, they can be combined by simply summing them together to have a stronger signal, or by combining (summing) scaled versions of each detector's output. This gives the modulation change detection system a reliable signal to work with thanks to spatial diversity.

[0063] Some radars may not follow a periodic pattern in their modulation parameter variations. This may reduce interference from other radars by using a form of randomness. In this case, the radar modulation pattern cannot be predicted based on the previous sweep / frame. However, other systems can be used to measure sweep parameters, such as chirp slope, from a small number of observations during a sweep or chirp. To calculate the slope of a sweep / chirp, methods such as an instantaneous frequency measurement receiver can be deployed. Here, the phase of the received signal relative to its delayed version is calculated. With knowledge of the fixed delay, the frequency of the signal can be calculated by dividing the delay by the phase and multiplying it by 2pi. Thus, using two samples of a signal with a known time between them during a chirp, we can estimate the bandwidth between the samples and, consequently, the chirp slope. Another way to identify the frequency of a signal is to use a group of filters that provide values ​​equivalent to matching the signal to the most relevant filter.

[0064] In summary, a radar modulation parameter detection system 420, 600 has been described. The system includes an antenna 610 or at least one antenna port configured to receive a radar signal 602 from a radar under test (RUT) 601. The type of antenna 610 may vary between implementations. Some implementations of the radar modulation parameter detection system may include only an antenna port to which different types of antennas can be connected to perform various types of tests and performance characterizations involving different RUTs. Antenna arrays and single antennas are possible.

[0065] The system includes a power detector 620, shown schematically in FIG. 6, configured to determine a temporal power level profile of a received radar signal. A power detector is generally some form of device or system that determines the power or magnitude of a signal as a function of time. A power detector may be implemented in hardware or a combination of hardware and software. For example, a system including an ADC and processing circuitry that performs an integration operation or absolute value function can be viewed as a power detector, as a diode-based pure hardware detector, and as a so-called root-mean-square (RMS) power detector that utilizes the nonlinear characteristics of MOSFET transistors to achieve RMS conversion. The term "temporal power level profile" should be broadly interpreted herein to mean some form of power level pattern as a function of time. Examples of temporal power level profiles include, for example, a radar frame period measured as the time period with significant output from the power detector, the average power level of the received radar signal, the amplitude pattern of the received radar signal, etc. Example temporal power delay profiles were discussed above in connection with FIGS. 7A-C.

[0066] The radar modulation parameter detection systems 420, 600 described herein also include a processing circuit 640 configured to obtain a record including at least two different radar modulation schemes, each radar modulation scheme in the record being associated with a respective radar modulation parameter and a respective temporal power level profile data input. In other words, the processing circuit has access to information regarding radar modulation schemes that may be used by the RUT at a given time. Each such modulation scheme is associated with several types of radar modulation parameters. As described above, it is these radar modulation parameters that can be used by the RUT to emulate a target, i.e., to configure a radar return transmission. A typical processing circuit of the type that can be used to implement the radar modulation parameter detection system herein is also described below in connection with FIG. 17.

[0067] The processing circuitry 640 is configured to identify the current modulation scheme of the RUT 601 from among at least two different radar modulation schemes based on a comparison between the determined temporal power level profile of the received radar signal and the temporal power level profile data entries in the recording. This means that the system checks to see which temporal power level profile data entries in the recording match the temporal power level profile detected by the power detector and uses the matching data entries to find the current radar modulation scheme. Thus, the system uses a simple and robust power detector to obtain a temporal power "fingerprint" of the current transmission and then converts this fingerprint into modulation parameters via the recording. Another way to look at this is that certain features of the temporal power level profile of the received radar signal (e.g., frame length) are used as a key to identify the correct radar modulation parameters in the recording.

[0068] The actual record can be configured in a variety of different ways. Manual configuration is one option, in which an operator enters the radar modulation schemes that can be used by a given radar system into a file, along with some type of temporal power level profile data entry for each modulation scheme. FIG. 4 shows a system for deployment of a radar target simulator (RTS) with a RUT 400, having a number of different components. A key component is a radar modulation parameter detection system 420 that detects changes in the modulation parameters of the RUT and notifies the rest of the system of these changes. Another component that may be advantageous to include in the target simulator is a modulation scheme detection subsystem 410 configured to identify radar modulation parameters in the radar modulation scheme. The processing circuitry can be configured to update the record with the identified radar modulation parameters. In this way, the record can be updated even if the modulation scheme of the RUT is unknown, which is advantageous. This functionality can also be used separately for automatic construction of records used by the radar modulation parameter detection system.

[0069] The radar modulation parameter detection system 420, 600 outputs at least one radar test system control signal determined based on the current modulation scheme of the RUT 601. This control signal should also be broadly interpreted to encompass not only a trigger signal but also a complete report of the modulation parameters used, statistics of the modulation parameters used, etc. Radar modulation parameters that can be obtained by the system in this manner include any of the radar signal bandwidth, chirp length, chirp period, chirp slope, chirp center frequency, antenna configuration, antenna activation pattern, and antenna transmission pattern.

[0070] Another way to describe the radar modulation parameter detection system is where processing circuitry 640 is configured to obtain a record including at least two different radar modulation schemes, where each radar modulation scheme in the record is associated with a respective radar modulation parameter and a respective temporal power level profile data entry, and processing circuitry 640 is configured to identify a current modulation scheme of the RUT 601 from among the at least two different radar modulation schemes in the record based on a one-to-one mapping between the determined temporal power level profile of the received radar signal and the temporal power level profile data entry in the record.

[0071] The record can also be used to describe a repeating time sequence of modulation schemes for the RUT 601. In this case, the processing circuit 640 can be configured to determine a future modulation scheme for the RUT 601 based on the RUT's 601's identified current modulation scheme and the repeating time sequence of modulation schemes, where the radar modulation parameter detection system 420, 600 is configured to output data indicative of the RUT's 601's future modulation scheme. This means that the record can include an indication of the order of the RUT's different schemes, allowing a radar test system that knows the order to identify where the RUT is in the order and predict which modulation scheme will be used in the future. For example, suppose the record contains three different modulation schemes A, B, and C with three corresponding temporal power level profiles, such as different frame lengths or different power levels. Further, suppose the record includes information indicating that the order used by the RUT is {A, A, B, A, C} in a repeating manner. In this case, the processing circuitry can use the output from the power detector, along with the information in the recording, to identify where in the sequence the RUT is currently located in a manner that synchronizes the action by the RTS with the point in the recording. Once this synchronization is achieved, the RTS can actively vary the modulation parameters, thus enabling radar testing of radar systems whose modulation parameters vary over time. The processing circuitry is optionally configured to determine the repeating time sequence of the modulation schemes of the RUT 601 based on a recursive analysis of the sequence of the detected modulation schemes of the RUT. One such method of recursive analysis is to perform a frequency analysis of the sequence of the detected modulation schemes and identify recurring patterns therein from their fundamental frequencies. Correlation analysis using increasing blocks of the detected modulation schemes can also be used. Methods of determining the repeating time sequence in a series of samples are generally known and will therefore not be described in further detail here.

[0072] According to an aspect, the processing circuit 640 is configured to detect the start and / or cessation of transmission by the RUT based on the determined temporal power level profile of the received radar signal. The radar modulation parameter detection system 420, 600 can also be configured to output a trigger signal that indicates the start and / or cessation of transmission by the RUT 601. The trigger signal can be used to control various operations of the RTS, such as initiating retransmissions or activating other functions. An example of this trigger signal can be seen in FIG. 4.

[0073] The received radar signal temporal power level profile and recorded temporal power level profile data input typically includes a frame time period measured from the onset of radar signal transmission to the cessation of radar signal transmission, as described above. The onset and cessation of radar signal transmission can be detected using power thresholds, and the frame time period can be determined using a timer or clock. Methods for configuring the thresholds were described above in connection with FIGS. 10 and 11.

[0074] The temporal power level profile of the received radar signal and the recorded temporal power level profile data input can include one or more power thresholds and a set of times at which the received radar signal crosses the threshold. This allows for defining more advanced power level profiles based on more than one power threshold. The temporal power level profile can include a first threshold indicating the start and pause of radar frame transmission, for example, along with a central portion of the frame containing a higher signal power transmission. As mentioned above, different power levels can also indicate a change in the transmit antenna of the RUT, because signals from different radar antennas to the antenna of the radar modulation parameter detection system 420, 600 are often associated with different levels of attenuation.

[0075] According to one aspect, the processing circuit 640 is configured to identify the current modulation scheme being used by the RUT 601 using comparison metrics including the time period of the temporal power level profile of the received radar signal and / or the power level of the temporal power level profile of the received radar signal and / or the amplitude pattern of the temporal power level profile of the received radar signal. Thus, the radar modulation parameter detection system looks at the output from the power detector and compares this output to different inputs in the recording using the time period and / or power level. The comparison between the determined temporal power level profile of the received radar signal and the temporal power level profile data inputs in the recording can include rising edge and / or falling edge threshold detection, as described above.

[0076] The record can further include at least two different sets of modulation schemes, where each set includes at least one modulation scheme, and the processing circuit can be configured to select which set to use based on an external input signal associated with the RUT. The external input signal can include, for example, a Controller Area Network (CAN) bus signal, an Ethernet signal, or a FlexRay bus signal. The external input signal can indicate, for example, the vehicle speed or yaw rate of the vehicle 100. Thus, the radar modulation parameter detection system can be configured to listen for the same signal as the RUT and look for a modulation scheme in the corresponding set of modulation schemes based on the external signal. In this way, the RTS can adapt its retransmissions in response to a change in the operating state of the RUT even before the change in operating state is triggered. Advantageously, the RTS can adapt its retransmission radar modulation parameters in response to, for example, a change in speed, in time alignment with the transmission by the RTS. In the broader case, the radar modulation parameter detection system does not use any external signal to identify the current set of modulation schemes, but rather uses the record to identify whether the RUT is switching to a different set of modulation schemes. If there is no longer any match between the temporal power level profile of the received signal in one set and the temporal power level profile data input, the system will look at all other sets in the record to find a match.

[0077] The radar modulation parameter detection system 400 can also be configured to output a lock signal if it successfully identifies the current modulation scheme of the RUT 601 among at least two different radar modulation schemes. This lock signal can be used to tag the output data from the RTS, thereby indicating validly obtained test results and distinguishing these valid results from invalid test data obtained without radar modulation scheme lock.

[0078] 16 illustrates a computer-implemented method, which also summarizes what has been described herein, that is implemented by a radar modulation parameter detection system 420, 600 (i.e., a system according to the description herein). The method includes receiving a radar signal 602 from a radar under test (RUT) 601 via an antenna 610 (S1); determining a temporal power level profile of the received radar signal via a power detector 620 (S2); obtaining a record (S3) including at least two different radar modulation schemes (each radar modulation scheme in the record is associated with a respective radar modulation parameter and a respective temporal power level profile data entry) via a processing circuit 640; identifying (S4) a current modulation scheme being used by the RUT 601 from among the at least two different radar modulation schemes in the record based on a comparison between the determined temporal power level profile of the received radar signal and the temporal power level profile data entry in the record; and outputting (S5) a radar test system control signal by a radar modulation parameter detection system 420, 600, determined based on the current modulation scheme of the RUT 601.

[0079] 17 illustrates components of a control unit 1700 according to an embodiment of the subject matter described herein, in relation to a number of functional units. This control unit may be included in the devices and systems described above. Processing circuitry 1710, which may be distributed across multiple units, may be implemented using any combination of one or more suitable central processing units (CPUs), multiprocessors, microcontrollers, digital signal processors (DSPs), etc., capable of executing software instructions stored in a computer program product, e.g., in the form of a storage medium 1730. Processing circuitry 1710 may further be implemented as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0080] In particular, processing circuitry 1710 is configured to cause control unit 1700 to perform a set of operations or steps, such as the method described in connection with FIG. 16 and elsewhere therein.

[0081] For example, storage medium 1730 can store a set of operations, and processing circuit 1710 can be configured to retrieve the set of operations from storage medium 1730 to cause control unit 1700 to perform the set of operations. The set of operations can be provided as a set of executable instructions. Accordingly, processing circuit 1710 is configured to thereby perform the methods disclosed herein. The control unit includes processing circuit 1710, an interface 1720 coupled to processing circuit 1710, and memory 1730 coupled to processing circuit 1710, the memory including machine-readable computer program instructions that, when executed by the processing circuit, cause the control unit to perform the methods described above in connection with FIG. 16 .

[0082] Storage medium 1730 may also include a non-removable storage medium, which may be, for example, any one or combination of magnetic memory, optical memory, solid-state memory, or remotely attached memory.

[0083] The control unit 1700 may further include an interface 1720 for communication with at least one external device. Accordingly, the interface 1720 may include one or more transmitters and receivers, including analog and digital components, and a suitable number of ports for wireline or wireless communication.

[0084] Processing circuitry 1710 controls the general operation of control unit 1700, for example, by sending data and control signals to interface 1720 and storage medium 1730, by receiving data and reports from interface 1720, and by retrieving data and instructions from storage medium 1730. Other components of the control node and associated functions are omitted so as not to obscure the components presented herein.

[0085] Figure 18 shows a computer readable medium 1810 carrying a computer program comprising program code means 1820 for performing the method shown in Figure 16 when the program product is run on a computer. The computer readable medium and the code means may together form a computer program product 1800.

Claims

1. In a radar modulation parameter detection system (420, 600) comprising an antenna (610) configured to receive a radar signal (602) from a radar under test (RUT) (601), a power detector (620) configured to determine a temporal power level profile of the received radar signal, and processing circuitry (640), the temporal power level profile being a power level pattern as a function of time, the processing circuitry (640) configured to obtain a recording including at least two different radar modulation schemes, each radar modulation scheme in the recording having a respective radar modulation parameter and a respective temporal power level profile. a processing circuit (640) configured to identify a current modulation scheme being used by the RUT (601) from at least two different radar modulation schemes in the recording based on a comparison between the determined temporal power level profile of the received radar signal and the recorded temporal power level profile data input; and the radar modulation parameter detection system (420, 600) configured to output a radar test system control signal determined based on the current modulation scheme of the RUT (601).

2. 2. The radar modulation parameter detection system (420, 600) of claim 1, wherein the radar modulation parameters include any of radar signal bandwidth, chirp length, chirp period, chirp slope, chirp center frequency, antenna configuration, antenna activation pattern, and antenna transmission pattern.

3. 3. The radar modulation parameter detection system (420, 600) of claim 1 or 2, wherein the record further describes a repeating time series of modulation schemes of the RUT (601), the processing circuit (640) is configured to determine a future modulation scheme of the RUT (601) based on the identified current modulation scheme of the RUT (601) and the repeating time series of modulation schemes of the RUT (601), and the radar modulation parameter detection system (420, 600) is configured to output data indicative of the future modulation scheme of the RUT (601).

4. A radar modulation parameter detection system (420, 600) according to any one of claims 1 to 3, wherein the processing circuit (640) is configured to detect the start and / or pause of transmission by the RUT based on the determined temporal power level profile of the received radar signal, and the radar modulation parameter detection system (420, 600) is configured to output a trigger signal indicating the start and / or pause of transmission by the RUT (601).

5. 5. The radar modulation parameter detection system (420, 600) of claim 1, wherein the received radar signal temporal power level profile and recorded temporal power level profile data input comprises a frame time period measured from the start of radar signal transmission to the cessation of radar signal transmission.

6. 6. The radar modulation parameter detection system (420, 600) of claim 5, wherein the onset and cessation of radar signal transmission are detected using a power threshold and the frame time period is detected using a timer or clock.

7. 7. A radar modulation parameter detection system (420, 600) as described in any one of claims 1 to 6, wherein the temporal power level profile of the received radar signal and the recorded temporal power level profile data input include at least one power threshold and a series of times at which the received radar signal exceeds the power threshold.

8. 8. The radar modulation parameter detection system of claim 1, wherein the processing circuitry is configured to identify a current modulation scheme used by the RUT using a comparison metric comprising a time period of the temporal power level profile of the received radar signal and / or a power level of the temporal power level profile of the received radar signal and / or an amplitude pattern of the temporal power level profile of the received radar signal.

9. 9. A radar modulation parameter detection system (420, 600) according to any one of claims 1 to 8, wherein the comparison between the determined temporal power level profile of the received radar signal and the recorded temporal power level profile data input comprises rising edge and / or falling edge threshold detection.

10. 10. The radar modulation parameter detection system (400) of claim 1, wherein the radar modulation parameter detection system (400) includes a modulation scheme detection subsystem (410) configured to identify radar modulation parameters in a radar modulation scheme, and wherein the processing circuitry is configured to update the record with the identified radar modulation parameters.

11. The radar modulation parameter detection system (400) of claim 3, wherein the processing circuitry is configured to determine a repeating time sequence of modulation schemes of the RUT (601) based on a recursive analysis of a series of detected modulation schemes of the RUT.

12. 12. The radar modulation parameter detection system (400) of claim 1, wherein the record includes at least two different sets of modulation schemes, each set including at least one modulation scheme, and the processing circuitry is configured to select which set to use based on an external input signal associated with the RUT.

13. 13. The radar modulation parameter detection system (400) of claim 12, wherein the external input signal comprises any of a controller area network (CAN), a bus signal, an Ethernet signal, or a FlexRay bus signal.

14. 14. The radar modulation parameter detection system (400) of claim 12 or 13, wherein the external input signal is indicative of a vehicle speed or a yaw rate of the vehicle (100).

15. 15. The radar modulation parameter detection system (400) of claim 1, configured to output a lock signal if the radar modulation parameter detection system (400) successfully identifies a current modulation scheme of the RUT (601) from among at least two different radar modulation schemes.

16. 16. The radar modulation parameter detection system (400) of claim 1, wherein the temporal power level profile is determined based at least in part on a comparison between an output of the power detector (620) and a threshold value, and the processing circuit (640) is configured to determine the threshold value based on a histogram of output samples from the power detector.

17. 17. The radar modulation parameter detection system of claim 16, wherein the processing circuitry is configured to determine a signal-to-noise (SNR) value based on the histogram.

18. A radar test system (400) comprising a radar modulation parameter detection system (400) according to any one of claims 1 to 17.

19. A computer-implemented method performed by a radar modulation parameter detection system (420, 600), the method comprising: receiving (S1) a radar signal (602) from a radar under test (RUT) (601) by an antenna (610); and determining (S2) a temporal power level profile of the received radar signal by a power detector (620); Including, A method wherein the temporal power level profile is a power level pattern as a function of time, obtaining (S3) by the processing circuitry (640) a record including at least two different radar modulation schemes, wherein each radar modulation scheme in the record is associated with a respective radar modulation parameter and a respective temporal power level profile data input; Identifying (S4), by the processing circuitry (640), a current modulation scheme being used by the RUT (601) from among at least two different radar modulation schemes in the record based on a comparison between the determined temporal power level profile of the received radar signal and the recorded temporal power level profile data input; and outputting (S5) a radar test system control signal determined based on the current modulation scheme of the RUT (601) by the radar modulation parameter detection system (420, 600); A method comprising:

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