Target simulator for a radar sensor

Abstract

The invention relates to a target simulator for a radar sensor, the target simulator having a receiving module for receiving radar signals in the form of radar radiation, a modification module for modifying the received radar signals and a transmitting module for transmitting the modified radar signals in the form of radar radiation, characterised in that the modification module has at least one radar chip for generating a first conversion signal and at least one second radar chip for generating a second conversion signal, wherein the modification module is configured to mix the first conversion signal with the received radar signals and thus generate radar signals with a reduced frequency, to process the radar signals with a reduced frequency so that processed radar signals are created, and to mix the second conversion signal with the processed radar signals and thus generate the modified radar signals.

Description

[0001] SMS, Smart Microwave Sensors GmbH Legal File:

[0002] In the Waashainen 1 2485-0076 PCT-1

[0003] 38108 Braunschweig

[0004] Germany Date:

[0005] November 25, 2025

[0006] Target simulator for a radar sensor

[0007] The invention relates to a target simulator for a radar sensor, wherein the target simulator comprises a receiver module for receiving radar signals in the form of radar radiation, a modification module for modifying the received radar signals and a transmitter module for emitting the modified radar signals in the form of radar radiation.

[0008] Radar sensors are used today in many technical fields, such as traffic monitoring. Radar sensors can be statically positioned along a traffic route, for example at an intersection, to monitor a section of that route and, for instance, control traffic lights at the intersection. Radar sensors can also be positioned on a vehicle, such as a car or truck, to monitor a portion of the vehicle's surroundings. Such radar sensors are used, for example, for distance warnings.

[0009] Radar sensors typically emit a radar signal in the form of radar radiation, which is reflected by an object, such as a road user. A portion of the reflected radar radiation is reflected back towards the radar sensor and detected. This requires at least one, preferably several, antennas to detect the reflected radar radiation. Today, radar radiation is often emitted as so-called FMCW radar (frequency modulated continuous wave radar). Unlike pulsed radar, which emits radar pulses, the radar sensor in FMCW transmits continuously, though not at a constant frequency. Often, the radar signals are emitted as successive frequency ramps. Each frequency ramp begins at a starting frequency and has a slope that measures the rate of change of the frequency.The frequency of the radar radiation changes and, for example, increases. This is common, but not necessary. In principle, decreasing frequency ramps are also possible. Every frequency ramp ends at a target frequency after a certain ramp duration.

[0010] Reflected radar radiation takes a certain amount of time to travel to the object and back to the radar sensor, a time that depends on the object's distance from the sensor. Comparing the transmitted and received frequency ramps yields a measurable frequency difference, which is proportional to the known slope of the frequency ramp multiplied by the time delay between the radar sensor and the reflecting object. This time delay is determined by the duration the radar radiation took to travel from the sensor to the object and back. Since the radar propagation speed is known, the object's distance can be calculated.

[0011] When the object is moving and a radial component of the movement is directed towards or away from the radar sensor, a frequency shift is added to the time offset, caused by the Doppler shift. These relationships have long been known to those skilled in the art and have been successfully applied for a long time.

[0012] To check or calibrate a radar sensor, one can aim it at an object or target moving at a known distance and speed. However, this is complex and practically impossible, especially for objects moving at large distances and / or high speeds. Radar sensors are also used, for example, for air traffic control or for large-scale monitoring of maritime shipping areas. Target simulators are therefore known from the prior art. For instance, US 11,822,769 B2 discloses a target simulator that emits signals simulating different targets with varying radial velocities and distances from the sensor.The target simulator is a so-called "handheld" device, meaning a device that does not need to be set up in a stationary position, but can be held in the hand by the user and then pointed at the sensor that is to be checked.

[0013] Alternatively, the sensor to be calibrated is pointed at the target simulator. In both cases, the radar radiation emitted by the sensor also reaches the target simulator. The target simulator has a receiver module and is therefore able to receive the incoming radar signals. The target simulator modifies the received signals as desired and sends the modified radar signals back to the radar sensor being calibrated. Modifications that the target simulator can achieve include, for example, a time delay in the return of otherwise unchanged radar signals to simulate a more distant target. Another modification is, for example, a constant frequency shift to simulate a moving target. The frequency shift corresponds to a Doppler shift caused by the object's movement.Preferably, target simulators can also amplify the radar signals to a greater or lesser degree, thus simulating larger and smaller targets. The various modifications can also be performed simultaneously. These are not only advantageous embodiments of target simulators from the prior art, but also advantageous embodiments of target simulators according to the invention.

[0014] A disadvantage is that such target simulators are expensive and complex. The invention therefore aims to further develop a target simulator of the type described above in such a way that it can be manufactured more easily and cost-effectively.The invention solves the stated problem by a target simulator according to the preamble of claim 1, which is characterized in that the modification module comprises at least one radar chip for generating a first conversion signal and at least one second radar chip for generating a second conversion signal, wherein the modification module is configured to mix the first conversion signal with the received radar signals to generate radar signals with a reduced frequency, to process the radar signals with the reduced frequency to produce processed radar signals, and to mix the second conversion signal with the processed radar signals to generate the modified radar signals. The modification module preferably comprises a first mixer for mixing the received radar signal with the first conversion signal.The modification module preferably includes a second mixer for mixing the processed radar signal with the second conversion signal.

[0015] A radar chip is preferably a "radar IC," i.e., a radar integrated circuit. It preferably includes a signal generator, preferably a PLL-based signal generator (PLL: phase-locked loop). This signal generator is capable of generating a radar signal, preferably a mmWave signal, i.e., a signal with a wavelength in the millimeter range. The signal generator is particularly preferably a digital signal generator. In addition to the signal generator, a radar chip has at least one antenna output through which the signals generated by the signal generator can be transferred to a transmitting antenna connected to the antenna output and thus transmitted. The transmitting antenna is preferably not part of the radar chip.

[0016] According to the invention, the received radar signals are mixed with the first conversion signal in the modification module. The radar signals have a frequency preferably between 24 GHz and 81 GHz, particularly between 60 GHz and 64 GHz, or between 76 GHz and 81 GHz, particularly 76 GHz or 77 GHz. Alternatively, the radar radiation has a frequency of 120 GHz or 240 GHz. This is referred to as the fundamental frequency of the radar radiation. The fundamental frequency can be modulated in the case of frequency-modulated radar radiation, with the difference between the starting frequency and the target frequency being several orders of magnitude smaller and, for example, a few MHz or a few GHz. Preferably, the difference is between 50 MHz and 5 GHz. This difference is also referred to as the bandwidth of the signal.The first conversion signal preferably has a fundamental frequency that is also several GHz and preferably corresponds to the fundamental frequency of the received radar signals. By mixing the received radar signals with the first conversion signal, the signals are "down-converted," a process often described in the prior art as "down conversion." This mixing results in radar signals with a reduced frequency, whose fundamental frequency is, for example, in the range of 10 GHz to 20 GHz. In this frequency range, the signals can be processed much more easily and with significantly less expensive components. It is important that this range is large enough to encompass the bandwidth of the radar signal.

[0017] For the present invention, it is not necessary for the radar signals to be in the form of FMCW or continuous wave (CW) radar signals. The radar signals can also be pulsed radar signals. The modified radar signals correspond to the radar signals in this respect. If the radar signals are in the form of FMCW or CW signals, the modified radar signals are also in the form of FMCW or CW signals, even if the frequency and / or amplitude have been changed. If the radar signals are pulsed signals, then the modified radar signals are also pulsed signals, with the frequency and / or amplitude also being changed.

[0018] According to the invention, the first conversion signal is generated by a radar chip. A radar chip is capable of generating radar signals and preferably has at least one transmit signal output. This allows the generated signals, also known as local oscillator (LO) signals, to be transferred to a transmitting antenna, preferably to several transmitting antennas, and then transmitted. In a target simulator described here, the radar signal generated by the radar chip at the transmit signal output is not fed to an antenna, but is used as the first conversion signal and fed to a mixer. The frequency of the first conversion signal differs from that of the radar signals. Preferably, the frequency of the first conversion signal is selected such that the reduced-frequency radar signals are in the range of 10 GHz. Preferably, the reduced-frequency radar signals have a fundamental frequency of 10 GHz.

[0019] After the received radar signals have been down-converted in this way, so that they are referred to as reduced-frequency radar signals, they are processed to produce modified radar signals. The modified radar signals also have a reduced frequency compared to the received radar signals. Preferably, the modification module includes, for example, a high-frequency transmission line through which the reduced-frequency radar signals are passed to delay the signals relative to the received radar signals. This is preferably done via two media converters and a fiber optic cable connection. A first media converter converts the high-frequency signal into light. The signal thus converted then travels through a fiber optic line and is converted back into a high-frequency signal. This method is preferably used because it is a cost-effective way to achieve long delays.The delay can range from a few meters to several kilometers.

[0020] Preferably, the maximum delay is 300 m.

[0021] Alternatively or additionally, the radar signal is amplified at a reduced frequency. The modification module therefore preferably includes an amplifier whose gain factor is preferably adjustable.

[0022] The processed radar signals are then mixed with the second conversion signal. According to the invention, the second conversion signal originates from at least one second radar chip and is preferably a local area (LO) signal. It has a fundamental frequency of several GHz. By mixing ("up-conversion") the processed radar signals with the second conversion signal in the second mixer of the modification module, the resulting modified radar signals again have the same or a similar fundamental frequency in the radar range as the received radar signals, i.e., several GHz, preferably between 76 GHz and 81 GHz. Preferably, the fundamental frequency of the modified radar signals is identical to the fundamental frequency of the received radar signals. This is particularly true if the target simulator is not intended to simulate a Doppler shift.Otherwise, there is a constant frequency offset between the fundamental frequency of the received radar signals and that of the modified radar signals, which is, for example, less than 2 GHz and which simulates a Doppler shift and thus a moving target.

[0023] Preferably, the fundamental frequency of the two conversion signals is identical. Alternatively, the fundamental frequency of the two conversion signals is different. Particularly preferably, the two conversion signals have a constant frequency offset.

[0024] Preferably, the modified radar signals correspond to the received radar signals with a constant frequency offset, a fixed time delay, and attenuation of the signal gain. Particularly preferably, the target simulator has an input device through which a distance and radial velocity of the target to be simulated can be entered. This distance is converted into the time delay, and the radial velocity into the constant frequency offset, and preferably, along with a desired attenuation and / or gain, are passed to the modification module.

[0025] Preferably, the first conversion signal is a first sequence of frequency ramps. These ramps have a first starting frequency, a first target frequency, and a first slope. This ensures that the duration of each individual frequency ramp is uniquely determined. Preferably, the second conversion signal is a second sequence of frequency ramps. These ramps have a second starting frequency, a second target frequency, and a second slope. This ensures that the duration of each individual frequency ramp is also uniquely determined. In both the first and second sequences of frequency ramps, all frequency ramps are identical. This is particularly relevant if the target simulator is not intended to simulate a Doppler shift.

[0026] Otherwise, the first and second frequency ramps exhibit a constant frequency offset, which is, for example, less than 2 GHz and simulates a Doppler shift and thus a moving target. In this case, the bandwidth of the first and second frequency ramps, as well as their respective durations and therefore their slopes, are identical.

[0027] By mixing ("down-converting") the received radar signals with the first conversion signal, the reduced-frequency radar signals become a sequence of frequency ramps, even if the received radar signals do not contain any frequency ramps. When mixing the signals with the respective conversion signals, the ramp characteristics of the conversion signals are transferred and, if applicable, superimposed on any existing ramp characteristics of the received or processed radar signals.

[0028] Preferably, the modification module is configured to mix the first conversion signal with the received radar signals such that the reduced-frequency radar signals are a sequence of frequency ramps, and to mix the second conversion signal with the processed radar signals such that the modified radar signals do not contain frequency ramps, provided that the received radar signals also do not contain frequency ramps. This can be achieved particularly easily if the first sequence of frequency ramps and the second sequence of frequency ramps simultaneously assume their respective starting and target frequencies, i.e., are synchronized, and their slopes do not differ in sign.

[0029] Advantageously, the modification module is configured, in the event that the received radar signals are a sequence of frequency ramps, to mix the first conversion signal with the received radar signals in such a way that the radar signals with reduced frequency are a sequence of frequency ramps, and to mix the second conversion signal with the processed radar signals in such a way that the modified radar signals are a sequence of frequency ramps which correspond to the frequency ramps of the received radar signals with respect to the start frequency, the target frequency and the slope.

[0030] The target simulator does not require, nor does it possess, information about the type of radar signal being received. It does not need information about the precise frequency, slope, or timing of the radar signal. The first and second conversion signals within the target simulator are synchronized. This means there is a controlled frequency offset between the two conversion signals. This frequency offset can be 0 Hz if the target simulator is intended to simulate a static target, i.e., one that is not moving relative to the sensor being calibrated. Alternatively, a fixed frequency offset, for example, 50 kHz, can be used between the two conversion signals if the target simulator is intended to simulate a target moving at a constant speed relative to the sensor being calibrated.

[0031] If the frequency of the received radar signals is F_received and the frequency of the first conversion signal is F_L01, then the frequency of the radar signals with reduced frequency after the first mixing is

[0032] F_mix1 = F_received - F_L01.

[0033] If the frequency of the second conversion signal is F_L02, then the frequency of the modified radar signals is

[0034] F_modified = F_mix1 + F_L02 = F_received + (F_L02-F_L01 ).

[0035] The difference (F_L02-F_L01) is the Doppler frequency added to the incoming radar signal. If both frequencies are synchronized, it is not necessary to know the exact frequencies, since the difference between them is known.

[0036] The two radar chips are preferably synchronized.

[0037] If conversion signals are frequency-synchronized, they could even

[0038] Modulating conversion signals with a slow FMCW ramp with the same frequency slope will achieve the same result as unmodulated conversion signals, since the frequency difference between the conversion signals is important.

[0039] Preferably, each radar chip has at least one signal generator for generating radar signals and at least one transmitting antenna output, wherein the signal generator is preferably a PLL-based signal generator.

[0040] Preferably, the target simulator has a local energy storage device for electrical energy, in particular a rechargeable battery. Preferably, the target simulator can be operated with a battery. Preferably, the target simulator is portable, i.e., it can be used handheld. This is also referred to as "handheld." It is preferably mountable on a tripod.

[0041] The target simulator has low energy consumption and can be battery-operated. With a built-in 40 Wh battery, it can operate for approximately 4 hours. It is also possible to power the device via USB and operate it continuously without batteries. The device weighs less than 1 kg and measures approximately 200 mm x 120 mm x 50 mm.

[0042] Preferably, the target simulator is equipped with an interface, preferably a wireless interface, for data communication. For example, it has a Bluetooth or WLAN interface. This makes it possible to transmit information about the target to be simulated, such as its distance and radial velocity, to the target simulator. Preferably, the actual distance between the radar source, whose radiation is received by the receiver module, is also transmitted to the target simulator.

[0043] In a preferred embodiment, the radar chips are prefabricated assemblies (off-the-shelve integrated circuits) used for the target simulator. These assemblies can be radar chips of the type used in the automotive industry and other industries to generate radar radiation. Preferably, the first and second radar chips are configured as "radar sensors on a chip," such that they additionally include at least one receiving antenna input. In some embodiments, such a radar sensor also includes at least one receiving antenna.

[0044] Preferably, the first radar chip and / or the second radar chip includes a microcontroller for controlling a user interface of the target simulator, remote control functions, power supply status and / or settings and information about the target to be simulated.

[0045] A chip according to the present invention is preferably a highly integrated, commercially available single- or multi-chip implementation containing the necessary electrical components for realizing a radar sensor and preferably also a radio link. A radar chip according to the present invention has at least one master clock or oscillator input for synchronizing all chip-internal timing circuits, at least one, preferably digital, PLL (phase-locked loop) signal generator for generating radar waveforms or for generating communication modulations, and at least one transmit signal output at the desired radar / communication radio frequency. Preferably, one or more master clock or oscillator outputs are also included to synchronize multiple chips.

[0046] Preferably, a radar chip has at least one receive signal input for signals of the desired radar / communication radio frequency, at least one down-conversion converter in the receive signal input path for frequency conversion of the received radar signal to a lower frequency, usually referred to as the intermediate or baseband frequency, and / or at least one intermediate or baseband signal chain after the down-conversion converter in which the intermediate or baseband signal is filtered and amplified. Preferably, a radar chip has at least one analog-to-digital converter (ADC) connected to the output of the intermediate or baseband signal chain to convert the received signal from the analog to the digital domain, one or more analog intermediate or baseband frequency signal outputs for external signal processing, and / or at least one general-purpose input / output for communication / control of electronic peripherals.

[0047] Preferably, a radar chip includes one or more digital-to-analog converters (DACs) for controlling electronic peripherals. Particularly preferably, all these elements of a radar chip, if present, are arranged on a single circuit board.

[0048] With the aid of the accompanying figures, some exemplary embodiments of the present invention are explained in more detail below. They show:

[0049] Figure 1 - a schematic view of the structure of a target simulator,

[0050] Figure 2 - a more detailed representation of a functional diagram of a

[0051] Target simulator.

[0052] Figure 1 schematically shows the structure of a target simulator according to an embodiment of the present invention. The target simulator has a receiver module 2, which is represented as an antenna and is configured to receive incoming radar radiation 4. The target simulator also has a modification module comprising a first radar chip 6 and a second radar chip 8. The first radar chip 6 and the second radar chip 8 are synchronized by means of a synchronization module 10. The first radar chip 6 is configured to generate a first conversion signal, which is mixed with the received radar signals in a first mixer 12. In a processing module 14, the radar signals generated in the first mixer 12 are processed at a reduced frequency, for example, by amplification.Additionally or alternatively, a high-frequency line is provided in the processing module 14, through which the signal is routed to create a time offset between the input of the incident radiation and the emission of the outgoing radiation 16. Processed radar signals are generated in the processing module 14 and then mixed in a second mixer 18 with time conversion signals generated in the second radar chip 8. The resulting modified radar signals are transmitted by a transmitter module 20.

[0053] Figure 2 shows a more detailed representation of the target simulator's structure. The first radar chip 6 and the second radar chip 8 are synchronized by the synchronization module. The target simulator includes the receiver module 2, which transmits received radar signals to the first mixer 12, where they are mixed with the first configuration signals from the first radar chip 6 to generate reduced-frequency radar signals. The target simulator also includes a calibration module 22, which calibrates the first conversion signals from the first radar chip 6 and the second conversion signals from the second radar chip 8. The reduced-frequency radar signals generated in the first mixer 12 are amplified in an amplifier 24. To achieve the time offset from the outgoing radiation, the target simulator, shown schematically in Figure 2, includes a high-frequency transmission line 26.

[0054] The processed radar signals thus generated are mixed in the second mixer 18 with the second conversion signals generated in the second radar chip 8. The resulting modified radar signals are transmitted by the transmitter module 20.

[0055] The target simulator includes an electrical circuit for changing the amplitude level of the received radar signal. The amplitude of the outgoing radiation 16 emitted via the transmitting antenna 20 is proportional to the radar cross-section of the target simulated by the target simulator. In the illustrated embodiment, the method for changing the radar signal amplitude is implemented using a standard, programmable digital step attenuator 28. The function of the digital step attenuator 28 is to reduce or attenuate the radar signal in discrete digital steps, preferably based on a value programmed via a user interface 30. The use of a digital step attenuator 28 is not the only method that can be chosen for controlling the radar signal level.Other commercially available electronic circuits implementing a variable voltage attenuator, a variable voltage amplifier, or even a digital step-down amplifier are also available to achieve the same function of the digital step-down attenuator and to enable controllable amplitude changes of the transmitted radar signal. Control of the adjustable attenuation is achieved via the connection to the first radar chip 6. A user can select a predefined attenuation value via the user interface 30 and a user display 32, whereupon the first radar chip 6 generates the necessary signals to control the digital step-down attenuator to the selected attenuation value.

[0056] The target simulator in Figure 2 has a user interface 30 for setting the target speed and the amplitude of the radar transmit signal, as well as for navigating menus and submenus. The user interface 30 has, for example, five tactile push-button switches, preferably with four of the switches arranged in a north, east, south, and west configuration, and the fifth switch located in the center of the four switches. The position of the switches allows for intuitive navigation through the menus and submenus, while the central switch allows the user to turn the device on and off by pressing and holding it, or, once the target simulator is on, to select menu items for changing values ​​by pressing and holding it briefly. The buttons of the user interface 30 are preferably monitored by the microprocessor of the first radar chip 6.When the user presses a key, the first radar chip 6 performs the corresponding action in the context of the current menu (e.g. menu navigation or value input) and sends appropriate commands to the user display 32 to update the displayed information.

[0057] The target simulator in Figure 2 features a two-line user display 32 for navigating the device's menu structure in standalone operation. The user display 32 can be transflective, backlit, or reflective. It allows the user to view and confirm device settings, such as target speed, relative amplitude, battery charge level, displayed units (e.g., m / s, km / h, or Hz), device software version, and other information. The user display 32 is preferably equipped with LED backlighting to ensure good readability even at night or in low-light conditions. The display's reflective properties allow for use in bright environments. The user display 32 is connected to the internal microprocessor of the first radar chip 6.The first radar chip 6 updates the user display 32 based on the current menu and the context of the key press.

[0058] The target simulator in Figure 2 features a remote control interface 34 for setting a target speed or Doppler frequency, the center frequency of the radar unit under test (RUT), and the adjustable step attenuator 28 via an external PC / laptop control using the PC / laptop's Universal Serial Bus. The remote control interface 34 is, for example, mechanically compatible with the standard Type C connector. The remote control interface 34 is particularly preferably compatible with a subset of the industry standard Standard Commands for Programmable Instruments (SCPI). The remote control interface 34 enables the user to automate the device settings for a radar sensor array, chamber, or end-of-line test environment.

[0059] The target simulator in Figure 2 has a battery management system 36 that handles the charging of a battery 38. When possible, the battery management system 36 negotiates the input voltage and charging current with the externally supplied DC power source. Furthermore, the battery management system 36 monitors the state of charge of the battery 38 and provides this information to the microprocessor of the first radar chip 6 of the target simulator.

[0060] The target simulator in Figure 2 preferably has three rechargeable batteries 38 for field use and an external power connection for charging the batteries 38 or for directly powering the target simulator. The rechargeable batteries 38 are, for example, the widely used and commercially available 18650 lithium-ion battery cell. The batteries 38 are accessible via a small access panel and can be removed or replaced by the user as needed.

[0061] The target simulator in Figure 2 has internal non-volatile memory 40 in which the user can, for example, save up to three user presets. Each user preset stores target settings, such as target speed, relative amplitude, and expected radar sensor center frequency. The user preset menu can be accessed and saved via the user interface 30 and viewed by the user on the user display 32. After saving the current device settings to the selected user preset, the preset values ​​can be recalled from the internal non-volatile memory 40, even after the target simulator has been switched off and / or the battery 38 has been replaced.

[0062] Reference symbol list

[0063] 2 receiver modules

[0064] 4 incoming radar radiation

[0065] 6 first radar chip

[0066] 8 second radar chip

[0067] 10 Synchronization module

[0068] 12 first mixer

[0069] 14 Processing module

[0070] 16 outgoing radiation

[0071] 18 second mixer / /

[0072] 20 transmitter modules

[0073] 22 Calibration module

[0074] 24 amplifiers

[0075] 26 High-frequency line

[0076] 28 Step damping element

[0077] 30 User interface

[0078] 32" user display, remote control interface, battery management system, battery, non-volatile memory

Claims

in te il ec tua ä proper ty sms, smart microwave sensors GmbH lawyer's file: In the Waashainen 1 2485-0076 PCT-1 38108 Braunschweig Germany Date: November 25, 2025 Patent claims 1. Target simulator for a radar sensor, wherein the target simulator - a receiving module for receiving radar signals in the form of radar radiation, - a modification module for modifying the received radar signals and - a transmitting module for emitting the modified radar signals in the form of radar radiation, characterized in that the modification module comprises at least one radar chip for generating a first conversion signal and at least one second radar chip for generating a second conversion signal, wherein the modification module is configured, - to mix the first conversion signal with the received radar signals and thus generate radar signals with a reduced frequency and - to process the radar signals with a reduced frequency, so that processed radar signals are created and - to mix the second conversion signal with the processed radar signals to generate the modified radar signals.

2. Target simulator according to claim 1, characterized in that the modified radar signals correspond to the received radar signals with a constant frequency offset and a fixed time delay.

3. Target simulator according to one of the preceding claims, characterized in that the first conversion signal is a first sequence of frequency ramps and the second conversion signal is a second sequence of frequency ramps.

4. Target simulator according to claim 3, characterized in that the modification module is configured in the event that the received radar signals do not contain frequency ramps, - to mix the first conversion signal with the received radar signals in such a way that the radar signals with reduced frequency are a sequence of frequency ramps, and - to mix the second conversion signal with the processed radar signals in such a way that the modified radar signals do not contain any frequency ramps.

5. Target simulator according to claim 3, characterized in that the modification module is configured for the case where the received radar signals are a sequence of frequency ramps, - to mix the first conversion signal with the received radar signals in such a way that the radar signals with reduced frequency are a sequence of frequency ramps, and - to mix the second conversion signal with the processed radar signals in such a way that the modified radar signals are a sequence of frequency ramps which correspond to the frequency ramps of the received radar signals with respect to the start frequency, the target frequency and the slope.

6. Target simulator according to one of the preceding claims, characterized in that the first radar chip and the second radar chip are synchronized.

7. Target simulator according to one of the preceding claims, characterized in that each radar chip has at least one signal generator for generating radar signals and at least one transmitting antenna output, wherein the signal generator is preferably a PLL-based signal generator.

8. Target simulator according to one of the preceding claims, characterized in that the target simulator can be operated with a battery.

9. Target simulator according to one of the preceding claims, characterized in that the target simulator is portable and preferably usable as a handheld device.

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