Target Simulator for Calibrating an Active Environmental Detection System

Abstract

The present invention relates to a target simulator for calibrating an active environmental detection system. A method for calibrating a target simulator of an active environmental detection system includes: calibrating a complete signal path including a first signal path and a second signal path by determining a first deviation between a first value of at least one signal parameter and a first reference value of the at least one signal parameter; calibrating one of the first signal path and the second signal path by determining a second deviation between a second value of the at least one signal parameter and a second reference value of the at least one signal parameter; and calibrating the other of the first signal path and the second signal path by compensating the first deviation with the second deviation.

Description

Technical Field

[0001] The present invention relates to the development and testing of active environment detection systems. Background Art

[0002] An environment detection system should be understood to mean a computer system equipped with sensor technology that can independently detect objects in its environment. Especially in the automotive industry, there is currently a trend towards automation, in the course of which vehicles are increasingly equipped with environment detection systems. However, such systems are also used in other fields, such as robotics, traffic monitoring or airspace monitoring. A distinction is made between passive and active systems, where passive systems are configured purely as signal receivers and active systems independently emit signals in order to use the echo signals reflected by them to detect objects. Traditional active environment detection systems are typically based on ultrasonic waves, radio waves (radar) or lasers (lidar).

[0003] Many active environment detection systems are provided for safety-critical tasks, such as the control of autonomous vehicles, such that correct functionality must be ensured before their production begins. In order to be able to test active environment detection systems safely and in a reproducible manner, target simulators exist on the market. These are test benches or components of test benches that simulate the operation of an active environment detection system in a normal environment via artificially generated echoes, with the active environment detection system being placed in or in front of the target simulator as a test piece. The target simulator includes: a receiving device in a first signal path for registering wireless signals generated by the test piece in order to detect objects in the environment; a transmitting device in a second signal path for generating a delayed echo signal; and a simulator device for controlling the transmitting device.

[0004] The basic function of the simulator device is to specify the time delay and signal characteristics of the simulated echo signal. The signal characteristics are defined by a set of parameters that can particularly include one or more of the following parameters: amplitude, frequency, phase, pulse width. Each of the aforementioned parameters can also be represented in multiple instances in the signal characteristics in order to describe the simulated echo signal as a superposition of multiple wave packets. Each parameter can be specified as an absolute value or a relative value. For example, the amplitude can also be predetermined as a scaling factor for the amplitude of the signal received at the receiving device, and the frequency can be predetermined as a frequency shift of the frequency of the signal received at the receiving device. The simulator device can also be configured to directly transmit parameters not predetermined by the signal characteristics from the signal received at the receiving device to the echo signal generated by the transmitting device. For example, the simulator device can be configured to specifically scale down the signal received at the receiving device by a scaling factor predetermined in the signal characteristics and transmit the received signal without modification other than the scaling via the transmitting device.

[0005] The signal characteristics of the transmitting device can be determined by the simulator device in various ways with different complexities. In the simplest case, the signal characteristics can be determined statically in advance. The signal characteristics can be selected from a predefined selection of signal characteristics or follow a predefined time curve. The signal characteristics can also be determined in advance by a complex computer simulation of the environment of the active environmental detection system, such that the signal generated by the transmitting device simulates the echo signal from a virtual object in the environment. The target simulator can also include more than one receiving device and more than one transmitting device to simultaneously simulate the echo signals from multiple objects. The transmitting device can be installed statically, or the transmitting device can be installed to be movable to simulate the echo signal from a moving object.

[0006] An example of such a target simulator is the radar target simulator DARTS provided by dSPACE GmbH for radar systems. In the radar target simulator, the receiving device is configured as a first antenna for receiving radar signals from a test piece designed as a radar system, and the transmitting device is designed as a second antenna for generating radar signals to simulate the radar echo of the radar signals received at the first antenna. In the lidar target simulator for lidar systems, the receiving device is designed as a light detector for receiving laser signals from a test piece designed as a lidar system, and the transmitting device is designed as a light source component for generating optical signals to simulate the light reflection of the laser signals received at the light detector.

[0007] Both radar systems and lidar systems generally require periodic recalibration after delivery because the components installed in the two signal paths change their electrical behavior with continued use. This problem concerns environmental detection systems and target simulators in the same way because both types of radar systems or lidar systems include a first signal path with a receiving device and a second signal path with a transmitting device. The signal paths are just used in a different order. When the environmental detection system first controls the transmitting device to evaluate subsequent echo signals via the receiving device, the target simulator first uses the receiving device to generate echo signals via the transmitting device. In both types of systems, the basic technical equipment of the two transmission paths is similar. Currently, each recalibration of the target simulator requires the disassembly of the target simulator and its relocation or a site visit by a technical service provider. For the operator, both of these result in high costs and long downtimes for the target simulator. Summary of the Invention

[0008] In an exemplary embodiment, the present invention provides a method for calibrating a target simulator of an active environmental detection system. The method includes: controlling, by a simulator device, a transmitting device to generate an electromagnetic test signal having predefined signal characteristics; reflecting the test signal to a receiving device via a reference reflector installed at a predefined spatial position relative to the receiving device and the transmitting device; measuring a first value of at least one signal parameter corresponding to the reflected test signal received at the receiving device; calibrating a complete signal path including a first signal path and a second signal path by determining a first deviation between the first value of the at least one signal parameter and a first reference value of the at least one signal parameter, wherein the first signal path includes the receiving device and the second signal path includes the transmitting device; installing a pre-calibrated calibration device at a predefined spatial position relative to the receiving device or the transmitting device, wherein: the pre-calibrated calibration device is configured to generate an electromagnetic calibration signal for the first path having predefined signal characteristics and transmit the electromagnetic calibration signal for the first path to the receiving device; or the simulator device is configured to control the transmitting device to generate an electromagnetic calibration signal for the second path having predefined signal characteristics, and the pre-calibrated calibration device is configured to receive the electromagnetic calibration signal for the second path from the transmitting device; measuring a second value of at least one signal parameter corresponding to the electromagnetic calibration signal for the first path or the electromagnetic calibration signal for the second path; calibrating one of the first signal path and the second signal path by determining a second deviation between the second value of the at least one signal parameter and a second reference value of the at least one signal parameter; and calibrating the other of the first signal path and the second signal path by compensating the first deviation with the second deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Embodiments of the present invention will be described in more detail below based on exemplary drawings. The present invention is not limited to the exemplary embodiments. In the embodiments of the present invention, all features described and / or illustrated herein can be used alone or in different combinations. By reading the following detailed description with reference to the drawings, the features and advantages of various embodiments of the present invention will become apparent, and the drawings are illustrated as follows:

[0010] Figure 1 A target simulator designed as a radar target simulator in normal operation is drawn;

[0011] Figure 2 Calibration of the complete signal path of a radar target simulator via a reference reflector is drawn;

[0012] Figure 3 Calibration of the first signal path of a radar target simulator via a calibration device designed as a radar transmitter is drawn; and

[0013] Figure 4 Drawn as Figure 3Alternative of the embodiment, calibration of the second signal path of the radar target simulator via a calibration device designed as a radar receiver. Detailed Description

[0014] Exemplary embodiments of the present invention simplify the calibration of a target simulator of an active environmental detection system.

[0015] In an exemplary embodiment of the present invention, calibration is performed using a well - defined reference reflector and a calibration device. First, the complete signal path including a first signal path with a receiving device and a second signal path with a transmitting device is calibrated via the reference reflector. To this end, the simulator device controls the transmitting device in such a way that the transmitting device generates a test signal with predefined signal characteristics provided for calibrating the complete signal path. The test signal is reflected by the reference reflector to the receiving device, which is mounted at a predefined spatial position relative to the receiving device and the transmitting device. The reflected test signal received at the receiving device is measured, i.e., after the reflected test signal is received at the receiving device, the simulator device determines at least one signal parameter value of the test signal provided for calibration.

[0016] Subsequently, a first deviation of the signal parameter determined in the reflected test signal from a first reference value of the signal parameter is determined. By determining the first deviation, the entire signal path is calibrated, but the individual signal paths are not yet calibrated. In other words, it is known what error the first signal path and the second signal path together impart to the signal parameter, but the specific contribution of the first signal path and the second signal path to the error is unknown. Given a target simulator, since the first and second signal paths are used independently of each other (the signal generated by the transmitting device is not a real echo but an artificially generated one), this is not sufficient; rather, both signal paths need to be calibrated.

[0017] To this end, a pre - calibrated, in particular pre - adjusted, calibration device is then installed in or in front of the target simulator, and the first signal path or the second signal path is calibrated via this calibration device. If the calibration device is provided for calibrating the first signal path, the calibration device is configured to generate an electromagnetic calibration signal with predefined signal characteristics and is mounted at a predefined spatial position relative to the receiving device such that the calibration signal is received by the receiving device. If the calibration device is provided for calibrating the second signal path, the calibration device is configured to receive and measure an electromagnetic calibration signal with predefined signal characteristics from the transmitting device, and the simulator device is configured to control the transmitting device to generate the calibration signal.

[0018] Measure the signal parameter to be calibrated in the calibration signal and subsequently determine a second deviation of the signal parameter measured in the calibration signal from a second reference value. According to an embodiment of the calibration device as a signal transmitter or a signal receiver, thus calibrate the first signal path or the second signal path.

[0019] Using the information now available, it is also possible, without further measurement, to calibrate the signal path that remains uncalibrated after the second deviation has been determined. For this purpose, it is only necessary to subtract the error contributed by the signal path that has already been calibrated from the total error determined via the reference reflector. Thus, the calibration of the signal path that remains uncalibrated after the second deviation has been determined is carried out by simply compensating the first deviation with the second deviation.

[0020] Preferably, the reference reflector is a three-sided mirror or a triangular prism, but other designs of the reference reflector for implementing the method according to the invention are also possible, such as a metal sphere for a radar target simulator or a plane mirror for a lidar target simulator. A well-defined reference reflector is understood to mean that the reference reflector is standardized in terms of its structural design such that the radiation of the reference reflector with a well-defined electromagnetic signal at a well-defined solid angle and from a well-defined distance produces a well-defined echo signal by the reference reflector.

[0021] In an embodiment, the target simulator advantageously includes a first holding device for mounting the calibration device and a second holding device for mounting the reference reflector. The holding devices are advantageously configured and mounted in or in front of the target simulator in such a way that they enforce correct installation in the respective specified spatial positions and correct alignment of the reference reflector or the calibration device. For this purpose, the holding devices can be installed, for example, in a closed or open test chamber of the target simulator and can be configured, for example, to lock, tighten, insert or support the reference reflector or the calibration device.

[0022] Exemplary embodiments of the method significantly reduce the cost and time overhead for calibrating the target simulator of an active environmental detection system. The user of the target simulator can perform it independently on-site with little effort, provided that a pre-calibrated calibration device is available to them, for example, if required, the pre-calibrated calibration device can be sent to them.

[0023] In an exemplary embodiment, some measurement processes and calculation steps for calibrating a target simulator are performed by a calibration device, thereby performing data exchange between the calibration device and the simulator device. For example, such data exchange can be performed in the following ways: via a bus connection automatically configured when the calibration device is attached, via a wired data connection (e.g., a Universal Serial Bus (USB) cable or an Ethernet cable); a radio connection, such as a Wireless Local Area Network (WLAN) or a Bluetooth connection; or also manually, for example, via an interface for PC (Personal Computer) connection at the simulator device and the calibration device.

[0024] The calibration device can preferably be configured as a pre-adjusted transmitter for generating an electromagnetic signal, that is, for calibrating a first signal path that is configured to generate a well-defined calibration signal. In this embodiment, all measurement and calculation steps of the exemplary embodiment for performing the method can be integrated into the simulator device. This embodiment enables a pre-adjusted calibration device to be provided to each user as an accessory, and multiple pre-adjusted calibration devices can be stored so that the user can periodically replace his calibration device with a newly adjusted one.

[0025] Advantageously, the target simulator is adjusted before first use, wherein a first reference value and a second reference value are measured at the adjusted target simulator. The determination of the first deviation and the second deviation is advantageously automated and functionally integrated into the simulator device. For this purpose, the first reference value and the second reference value are advantageously stored in a storage medium (e.g., a memory) readable by the simulator device, and the simulator device reads the first reference value from the storage medium to determine the first deviation, and reads the second reference value from the storage medium to determine the second deviation.

[0026] Advantageously, the target simulator independently performs the step of calibrating the complete signal path via a reference reflector to establish the calibration requirement for the target simulator, without the need for the user of the target simulator to initialize this step. For this purpose, the test bench can be configured to automatically determine the first deviation by generating a test signal after a defined time has passed and / or when a fixed event occurs (e.g., after the target simulator has been put into use or stopped being used); compare the first deviation with a threshold, and notify the user of the calibration requirement if the first deviation exceeds the threshold. After reporting the calibration requirement, the user can correctly attach the calibration device to implement the remaining method steps for calibrating the target simulator.

[0027] For the fully automatic determination of calibration requirements, a reference reflector can be permanently installed in the target simulator. In order to thereby minimize the echo signals of the unwanted reference reflector during the operating operation of the target simulator, the signal characteristics of the test signals stored in the simulator device can predetermine test signals of very high intensity, which intensity is substantially higher than the maximum intensity of the signals generated by the transmitting device expected during the normal operation of the target simulator. The reference reflector can then be configured to be correspondingly less or weakly reflective, such that its echo signals sound only faintly during the operating operation, weakly enough to be ignored as background noise.

[0028] Since the signal propagation time of the complete signal path is clearly defined and known, the simulator device can also be configured (in particular programmed) to deliberately ignore the echo signals generated by the reference reflector during the operating operation. However, this embodiment can be error-prone because in some cases, if the signals generated by the test piece (simultaneously with the echo signals) randomly arrive at the receiving device, this may lead to the ignoring of that signal.

[0029] In another embodiment of the target simulator, the reference reflector is configured to be deactivatable for the normal operation of the target simulator. For this purpose, the holding device of the reference reflector can be equipped with a mechanism that allows the removal, hiding, tilting or moving of the reference reflector. The target simulator can also be configured to only optionally perform the full automatic calibration of the complete signal path, as long as the reference reflector is installed according to the method described and not deactivated. For example, the simulation device can be configured to cyclically generate test signals, but only perform the calibration of the complete signal path and the determination of the calibration requirements when the receiving device receives the reflected test signals.

[0030] In yet another embodiment, the target simulator is configured to independently and fully automatically perform the determination of the calibration requirements, as described above, but is also configured to, after the determination of the calibration requirements, electrically mask, tilt or move the reference reflector, for example via an electrically operated mechanism, to fully automatically deactivate the reference reflector so as to prepare the target simulator for normal operation without the reference reflector.

[0031] Figure 1 The illustration of shows a radar target simulator 2 in normal operation. The radar target simulator 2 includes a simulator device 4 and a test chamber 16 that houses an environmental detection system as a test piece 14, which environmental detection system is configured to generate a radar signal 22, receive an echo signal 20 of the radar signal 22, and detect its environment using the echo signal, for example to locate an object or determine its speed.

[0032] The test chamber 16 includes a first antenna 10 as a receiving device and a second antenna 12 as a transmitting device. The first antenna 10 is configured to receive the radar signal 22 of the test piece 14, and the second antenna 12 is used to generate a radar signal so as to simulate the echo signal 20 of the radar signal 22 received at the first antenna 10.

[0033] The first antenna 10 is part of a first signal path 6, and the second antenna 12 is part of a second signal path 8. These two signal paths also respectively include signal lines to the simulator device 4 and electronic components for signal processing, preparation, and forwarding.

[0034] The central computer 18 is connected to the simulator device 4. The central computer 18 performs a simulation in which a virtual instance of the test piece 14 interacts with other virtual objects in a virtual environment and provides the spatial positions of the other virtual objects relative to the test piece 14 to the simulator device 4. The simulator device 4 includes a processor that, in response to receiving the radar signal 22 at the first antenna 10, predetermines the propagation time and signal characteristics of the virtual radar echo of the radar signal reflected by the virtual object. The simulator device 4 is also configured to control the second antenna 12 in such a way that it generates an echo signal 20 having the predetermined signal characteristics of the virtual radar echo and received from the test piece 14 just after a predetermined propagation time has elapsed.

[0035] Figure 2 The illustration shows the calibration of the complete signal path of the target simulator 2 via the reference reflector 24. The reference reflector is a three - mirror, and its structural design, positioning, and spatial alignment are precisely specified in the test chamber 16. The test chamber 16 includes a first holding device for the reference reflector 24, which enforces the correct positioning and alignment of the reference reflector 24. The complete signal path includes the first signal path 6, the second signal path 8, and the signal path from the second antenna 12 to the reference reflector 24 and back to the first antenna 10.

[0036] To calibrate the complete signal path, the simulator device 4 controls the second antenna 12 so as to generate a test signal 26 having signal characteristics predefined for the test signal. The signal characteristics are defined by one or more signal parameters, and at least one signal parameter is provided for calibration. If the goal of the calibration process is, for example, amplitude calibration, then the simulator device 4 then controls the second antenna 12 so as to generate a test signal 26 having a predefined amplitude. The reference reflector 24 reflects the test signal 26 to the first antenna 10. The simulator device 4 measures in the test signal 26 received at the first antenna 10 the parameter provided for calibration and determines a first deviation of the measured value of the parameter from a first reference value. The first reference value is stored in the storage medium of the simulator device 4 and is sourced from measurements performed after the initial adjustment of the target simulator 2 and before its first commissioning.

[0037] The target simulator 2 compares the first deviation with a threshold value stored in the same storage medium. If the first deviation exceeds the threshold value, the simulator device 4 reports the calibration requirement, for example, via a light-emitting display or a status report at the operator interface.

[0038] To calibrate the first signal path and the second signal path, the user of the target simulator 2 installs the calibration device 28 at the second holding device in the test chamber 16, as Figure 3 shown in the illustration. The second holding device forces the calibration device 28 to be installed at a predetermined spatial position in the measurement chamber 16.

[0039] The calibration device 28 is configured to generate a calibration signal 30 having predefined signal characteristics and transmit the signal 30 to the first antenna 10. The simulator device 4 measures the signal parameters to be calibrated in the calibration signal 30 and determines a second deviation of the measured signal parameters based on a second reference value of the signal parameters. Similar to the first reference value, the second reference value is stored in the storage medium and is sourced from measurements performed after the initial adjustment of the target simulator, before its first operation, and via the calibrated or adjusted calibration device 28.

[0040] To implement this method, the calibration device 28 is at least calibrated, preferably adjusted, so as to be able to determine a second deviation in the calibration signal 30 compared to the measured value of the parameter. Therefore, to implement this method, it is necessary to ensure the existence of a pre-calibrated calibration device 28.

[0041] The target simulator 4 calculates the error of the first signal path 6 from the second deviation and automatically stores this error in the storage medium for consideration in future measurements of the radar signal 22. The first signal path 6 is thus calibrated and adjusted. After determining the second deviation, since the error of the complete signal path can be derived from the first deviation, the second signal path 8 can also be calibrated in a simple manner. The error of the second signal path 8 is caused by the difference between the error of the complete signal path and the error of the first signal path 6. In this way, the target simulator compensates the first deviation using the second deviation, calculates the error of the second signal path 8, and stores the error of the second signal path in the storage medium for consideration when determining the signal characteristics of the echo signal 20 in the future. The second signal path 8 is thus also calibrated and adjusted.

[0042] In the simplest case, compensating the first deviation using the second deviation is a simple difference calculation. However, additional influencing variables, such as known errors or scaling factors in the generation of the calibration signal 30, can also be considered in the compensation to account for the different signal strengths of the reflected test signal 26 and the calibration signal 30.

[0043] Figure 4 The illustration of Figure 3 shows the alternative embodiment shown. The calibration device 28 is configured as a radar receiver instead of a radar transmitter, and the calibration signal 30 is generated by the simulator device 4 by controlling the second antenna 12. The pre-calibrated calibration device 28 measures the parameter to be calibrated in the calibration signal 30 received from the second antenna 12 and determines the second deviation of the measured parameter from the second reference value in order to determine the error of the second signal path 8, thereby calibrating the second signal path. By compensating the first deviation with the second deviation and then calibrating the first signal path 6 as described above. After sending the relevant information from the calibration device 28 to the simulator device 4, all the calculation steps for calibrating the second signal path can be performed in the calibration device 28 or in the simulator device 4.

[0044] The target simulator 2 shown in the figure is configured as a radar target simulator only as an example. All the method steps described with reference to the accompanying drawings can be similarly applied to a lidar target simulator. In a lidar target simulator, the first antenna 10 would instead be configured as a light detector; the second antenna 12 is configured as a light source, such as a photodiode, a matrix of photodiodes, or a laser component; the reference reflector 24 is configured as a suitable reflector for the light source, such as a mirror, a white surface, or a prism; the calibration device 28 is configured as a pre-calibrated light source or a pre-calibrated light detector; and the test piece 14 is configured as a lidar system.

[0045] Although the embodiments of the present invention have been illustrated and described in detail in the drawings and the foregoing description, such illustration and description shall be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications can be made by those of ordinary skill in the art within the scope of the appended claims. In particular, the present invention encompasses other embodiments having any combination of features from different embodiments described above and below. Additionally, the statements made herein characterizing the present invention refer to embodiments of the present invention and not necessarily to all embodiments.

[0046] The terms used in the claims shall be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the articles "a" or "the" in introducing an element shall not be construed as excluding a plurality of elements. Similarly, the recitation "or" shall be construed as inclusive, such that the recitation "A or B" does not exclude "A and B", unless it is clear from the context or the foregoing description that only one of A and B is intended to be recited. In addition, the recitation "at least one of A, B, and C" shall be construed as one or more of the group of elements consisting of A, B, and C, and shall not be construed as requiring each of the recited elements A, B, and C, whether A, B, and C are related as a class or otherwise. Further, the recitation "A, B, and / or C" or "at least one of A, B, or C" shall be construed to include any single entity of the recited elements, such as A, any subset of the recited elements (e.g., A and B), or the entire list of elements A, B, and C.

Claims

1. A method for calibrating a target simulator of an active environmental detection system, comprising: The simulator device controls the transmitting device to generate an electromagnetic test signal having predefined signal characteristics; The test signal is reflected to the receiving device via a reference reflector installed at a predefined spatial position relative to the receiving device and the transmitting device; Measure a first value of at least one signal parameter corresponding to the reflected test signal received at the receiving device; Calibrate the complete signal path including the first signal path and the second signal path by determining a first deviation between the first value of the at least one signal parameter and a first reference value of the at least one signal parameter, where the first signal path includes the receiving device and the second signal path includes the transmitting device; Install a pre-calibrated calibration device at a predefined spatial position relative to the receiving device or the transmitting device, where: The pre-calibrated calibration device is configured to generate an electromagnetic calibration signal for the first signal path having predefined signal characteristics and transmit the electromagnetic calibration signal for the first signal path to the receiving device; or The simulator device is configured to control the transmitting device to generate an electromagnetic calibration signal for the second signal path having predefined signal characteristics, and the pre-calibrated calibration device is configured to receive the electromagnetic calibration signal for the second signal path from the transmitting device; Measure a second value of the at least one signal parameter corresponding to the electromagnetic calibration signal for the first signal path or the electromagnetic calibration signal for the second signal path; Calibrate one of the first signal path and the second signal path by determining a second deviation between the second value of the at least one signal parameter and a second reference value of the at least one signal parameter; And Calibrate the other of the first signal path and the second signal path by compensating the first deviation with the second deviation.

2. The method according to claim 1, further comprising: Adjust the target simulator and measure the first reference value and the second reference value at the adjusted target simulator; 3. The method according to claim 1, further comprising: Store the first reference value and the second reference value in a memory readable by the simulator device; Read the first reference value via the simulator device to determine the first deviation; And Read the second reference value via the simulator device to determine the second deviation.

4. The method according to claim 1, further comprising: Automatically determine the first deviation after putting the target simulator into operation or taking the target simulator out of operation; Automatically compare the first deviation with a threshold; And Based on the first deviation exceeding the threshold, report the need to calibrate the target simulator.

5. The method according to claim 1, wherein: The target simulator is a radar target simulator for a radar system, The receiving device is a first antenna for receiving radar signals from a test piece configured as a radar system, and The transmitting device is a second antenna for generating radar echoes to simulate the radar signals received at the first antenna.

6. The method according to claim 1, wherein: The target simulator is a lidar target simulator for a lidar system, The receiving device is a photodetector for receiving laser signals from a test piece configured as a lidar system, and The transmitting device is a light source component for generating optical signals to simulate the optical reflection of the laser signals received at the photodetector.

7. A target simulator for an active environmental detection system, the target simulator comprising: A first signal path having a receiving device for receiving an electromagnetic signal from a test piece configured as an environmental detection system; A second signal path having a transmitting device for generating an echo signal of an electromagnetic signal to simulate a signal received at the receiving device; An emulator device for specifying signal characteristics of an echo signal after the receiving device has received a signal and for controlling the transmitting device to generate an echo signal having the signal characteristics; A reference reflector for reflecting a test signal generated by the transmitting device; A first holding device for holding the reference reflector at a predetermined spatial position relative to the receiving device and the transmitting device such that the reference reflector is configured to reflect a test signal generated by the transmitting device to the receiving device; A pre-calibrated calibration device configured to: generate an electromagnetic calibration signal for the first signal path having predefined signal characteristics; or receive an electromagnetic calibration signal for the second signal path having predefined signal characteristics from the transmitting device and measure the electromagnetic calibration signal for the second signal path; And A second holding device for mounting the pre-calibrated calibration device at a predetermined spatial position relative to the receiving device for the receiving device to measure the electromagnetic calibration signal for the first signal path, or at a predetermined spatial position relative to the transmitting device for the pre-calibrated calibration device to measure the electromagnetic calibration signal for the second signal path; Wherein the emulator device is configured to: Control the transmitting device to generate a test signal, wherein the test signal has predetermined signal characteristics; Measure a first value of at least one signal parameter corresponding to the test signal reflected by the reference reflector to the receiving device; Calibrate a complete signal path including the first signal path and the second signal path by determining a first deviation of the first value of the at least one signal parameter from a first reference value of the at least one signal parameter; Obtain a second value of the at least one signal parameter, wherein obtaining the second value of the at least one signal parameter includes: measuring the at least one signal parameter corresponding to the electromagnetic calibration signal for the first signal path; or controlling the transmitting device to generate an electromagnetic calibration signal for the second signal path for the pre-calibrated calibration device to measure the at least one signal parameter corresponding to the electromagnetic calibration signal for the second signal path; Calibrate one of the first signal path and the second signal path by determining a second deviation of the second value of the at least one signal parameter from a second reference value of the at least one signal parameter; and Calibrate the other of the first signal path and the second signal path by compensating the first deviation with the second deviation.

8. The target simulator according to claim 7, wherein, By removing, obscuring, tilting or moving the reference reflector, the reference reflector can be deactivated for normal operation of the target emulator.

9. The target simulator according to claim 7, wherein, The reference reflector is permanently and immovably mounted in the target emulator.

10. The target simulator according to claim 9, wherein, The predetermined signal characteristics of the test signal have a significantly higher intensity relative to the signal generated by the transmitting device during normal operation of the target emulator; And The signal reflected by the reference reflector to the receiving device during normal operation has negligible intensity.

11. The target simulator according to claim 9, wherein, The simulator device is further configured to: automatically determine a first deviation after the target simulator is put into operation or taken out of operation; compare the first deviation with a threshold; and report the need for calibration based on the first deviation exceeding the threshold.

12. The target simulator according to claim 7, wherein, The simulator device is further configured to: determine the error of the first signal path and store it in a memory; determine the error of the second signal path and store it in a memory; take into account the error of the first signal path in future measurements to adjust the first signal path; and take into account the error of the second signal path in future measurements to adjust the second signal path.

13. The target simulator according to claim 7, wherein: The target simulator is a radar target simulator for a radar system, the receiving device is a first antenna for receiving radar signals from a test piece configured as a radar system, and the transmitting device is a second antenna for generating radar echoes to simulate the radar signals received at the first antenna.

14. The target simulator according to claim 7, wherein: The target simulator is a lidar target simulator for a lidar system, the receiving device is a photodetector for receiving laser signals from a test piece configured as a lidar system, and the transmitting device is a light source component for generating optical signals to simulate the optical reflection of the laser signals received at the photodetector.

Images