Radar system, method for operating a radar system, radar receiver, central unit and method for operating the same

Abstract

The invention relates to a radar system (100) and a method for operating a radar system (100). Furthermore, the invention relates to a radar receiver (70) and a central unit (10) of such a radar system (100). In addition, the invention relates to a method for operating a radar receiver (70) and a method for operating a central unit (10). It is intended that a radar echo signal received by the radar system (100) is converted into a different frequency range by means of an optical mixer. In contrast to electronic mixers, optical mixing of the radar echo signal has the advantage of reduced power consumption and space requirements.

Description

[0001] The invention relates to a radar system and a method for operating a radar system. Furthermore, the invention relates to a radar receiver and a central processing unit of such a radar system. In addition, the invention relates to a method for operating a radar receiver and a method for operating a central processing unit.

[0002] For automated driving, the safest possible environmental perception is essential. In modern vehicles, the vehicle's surroundings are captured using environmental sensors such as radar, LiDAR, and cameras. The primary goal is a comprehensive 360° 3D mapping of the environment, enabling the detection of as many static and dynamic objects as possible within the vehicle's vicinity. LiDAR technology, in particular, is well-suited for redundant, robust environmental perception, as this type of sensor can be used precisely for environmental detection, distance measurement, and object classification. However, these sensors are expensive and complex to design.Particularly problematic is 360° 3D environmental mapping using LiDAR technology, as it requires either numerous small individual sensors, typically operating with many individual light sources and detector elements, or expensive large sensors to ensure such comprehensive environmental coverage. Furthermore, LiDAR systems are known to be susceptible to weather conditions such as rain, fog, or direct sunlight. This weather dependency, in particular, makes reliable environmental mapping with LiDAR systems difficult.

[0003] Radar sensors have been established in the automotive sector for years and deliver reliable and fail-safe data in all weather conditions. Even poor visibility, such as rain, fog, snow, dust, and darkness, hardly affects their detection reliability. However, their resolution—unlike LiDAR sensors—is more limited. Radar systems installed in modern vehicles typically achieve a resolution of up to approximately 5° (degrees). However, to meet the requirements for Level 4 and / or 5 automated driving with safe driving functions, radar sensors would need to deliver three-dimensional images with a fine resolution in the range of 0.1° (degrees) and even finer, with high insensitivity to interference from their surroundings. This cannot be achieved with conventional radar technology, as the resolution of existing systems is too low.

[0004] Current developments in photonic radar systems rely on the cointegration of electronic and photonic components in a single semiconductor. The generation of the FMCW signal, as well as all signal processing and evaluation, is performed by a central station. The transmit and receive modules consist of an electronically and photonically cointegrated chip (so-called "EPIC chip"). Silicon photonics technology is used for this cointegration. This enables the monolithic integration of photonic components, high-frequency electronics, and digital electronics together on a single chip ("electronic-photonic cointegration").

[0005] An example of a photonic radar system is disclosed in document DE 10 2017 221 257 A1. In this system, GHz signals are transmitted using an optical carrier signal in the THz frequency range. The signal to be transmitted is modulated onto an optical carrier signal generated by the central station at, for example, 1 / 8 of the radar frequency and sent to the antenna chips via optical fiber. The antenna chips then undergo an eightfold frequency amplification, allowing the radiation to be emitted from them in its original form. Signal detection occurs accordingly in reverse.

[0006] In photonic radar systems, downconversion of signals in the GHz range to the sub-GHz range is necessary. Unlike RF band detection, optical frequencies oscillate too rapidly to directly measure and electronically process the electric field. Therefore, in conventional radar systems, downconversion of the radar echo signal is performed using dedicated electronic circuits (mixers). However, electronic mixers increase power consumption and the required chip area.

[0007] The invention is based on the objective of developing a radar system and a method for operating a radar system that requires less power consumption and less space.

[0008] The problem according to the invention is solved by a radar system and a method for operating a radar system according to the independent claims. Preferred embodiments are the subject of the respective dependent claims.

[0009] A first aspect concerns a (photonic) radar system. The radar system comprises at least one radar transmitter, at least one radar receiver, and a central unit, which is coupled to the (at least one) radar transmitter and the (at least one) radar receiver via at least one (optical) waveguide. Preferably, the central unit is coupled to the radar transmitter via a first waveguide and to the radar receiver via a second waveguide. Additionally or alternatively, the radar transmitter and the radar receiver are coupled to the central unit via the same waveguide. Preferably, an optical fiber, for example, a glass fiber, is used as the waveguide.

[0010] The central unit comprises a signal generator configured to produce an electrical radar ramp signal and an optical transmitter unit configured to provide an optical radar carrier signal and an optical radar driver signal based on the electrical radar ramp signal generated by the signal generator. Preferably, the optical radar carrier signal and the optical radar driver signal are coupled into one or more waveguides as (independent) individual signals. In another embodiment, the optical radar driver signal is superimposed onto the optical radar carrier signal. In other words, the optical transmitter unit is preferably configured to modulate the electrical radar ramp signal generated by the signal generator onto the optical radar carrier signal as an optical radar ramp signal.The radar ramp signal causes the frequency of the radar carrier signal to be varied within a specific frequency range (frequency-modulated radar, FMCW). Consequently, the optical radar signal is preferably a superposition of the optical radar carrier signal and the optical radar ramp signal. The optical radar carrier signal is preferably an unmodulated continuous wave signal. The frequency of the optical radar carrier signal is preferably in the THz range. The frequency of the radar ramp signal is preferably in the GHz range. The optical transmitter unit is further configured to couple the optical radar carrier signal and the optical radar driver signal into the at least one waveguide. In other words, the central unit provides an optical radar driver signal, containing a predefinable or predetermined radar ramp signal, which is transmitted via the waveguide to the radar transmitter and radar receiver units.The optical transmitter unit preferably comprises a laser diode and / or a modulator, in particular an optical modulator. The use of a modulator has the advantage that the laser diode itself does not need to be modulated, but only needs to provide the optical carrier signal in CW (Continuous Wave) mode. This allows the use of a cost-effective laser diode. The laser diode is preferably configured to emit light with a wavelength of at least 1000 nm to at most 1800 nm, preferably at least 1200 nm to at most 1600 nm, and particularly preferably 1310 nm and / or 1550 nm. The signal generator is preferably configured to generate the radar ramp signal as an electrical radar ramp signal and to provide the electrical radar ramp signal to the optical transmitter unit.

[0011] The radar transmitter unit comprises an optical receiver and a radar transmitter. The optical receiver of the radar transmitter unit is configured to receive the optical radar driver signal coupled into the waveguide (by the optical transmitter of the central unit) and convert it into an electrical radar driver signal. Preferably, the optical receiver of the radar transmitter unit is configured to receive the optical radar carrier signal coupled into the waveguide (by the optical transmitter of the central unit). The optical receiver is further configured to provide the (converted) electrical radar driver signal to the radar transmitter (for driving it). In other words, the radar transmitter is enabled to be driven by the electrical radar driver signal to transmit a frequency signal containing the radar ramp signal (generated in the central unit).The optical receiver is preferably a photodiode. Photodiodes are well suited to converting the optical radar driver signal into an electrical radar driver signal.

[0012] The radar receiving unit comprises a radar receiver and an optical modulation unit configured to provide an optical radar response signal, which includes an optical radar echo signal generated based on a radar echo signal received by the radar receiver and preferably the optical radar driver signal, and to couple this signal into the waveguide. In other words, the radar echo to the frequency signal transmitted by the radar transmitter according to the radar ramp signal is received by the radar receiver and provided to the optical modulation unit as an electrical radar echo signal. The radar echo signal is a time-shifted copy of the optical radar driver signal, dependent on the distance to the target. The optical modulation unit is thus configured to convert the received electrical radar echo signal into an optical radar echo signal and to couple this into the waveguide as an optical radar response signal.The optical modulation unit is preferably configured to convert the received electrical radar echo signal into an optical radar echo signal and to modulate it onto the optical radar driver signal received by the central processing unit via the waveguide in order to generate the optical radar response signal, which is transmitted to the central processing unit via the waveguide. In other words, the optical radar response signal to be coupled into the waveguide can comprise (only) the optical radar echo signal or already the radar echo signal modulated onto the optical radar carrier signal. Thus, in the first case, the radar receivers can be manufactured and provided in a compact design with small dimensions. This saves installation space and costs. In the second case, parts of the signal processing can already be offloaded from the central processing unit to the radar receivers.This can be particularly advantageous for both distributed radar systems with a large number of radar transmitting and receiving units, each communicating with the central unit via waveguides, since the central unit then receives pre-processed signals from the radar receiving units.

[0013] The central unit further comprises a central optical receiver unit configured to receive the optical radar response signal coupled into the waveguide, and an evaluation unit configured to evaluate the received optical radar response signal and output radar information derived therefrom. Preferably, the evaluation unit is configured to perform a frequency analysis by means of a Fourier transform and thereby determine both a (time-of-flight-based) range coordinate of the target(s) and its Doppler frequency (relative velocity). For example, the range coordinate of the target(s) can be determined in the receiver channel of the central unit by cross-correlation of the radar response signal with the radar driver signal. The Doppler frequency shift is preferably also calculated by a correlation filter and / or a correlation filter bank.If two or more receivers are positioned spatially offset from each other, directional information about the incoming wave can be determined by evaluating the differences in their travel time. Preferably, the radar information derived from the optical radar response signal is output to a driver assistance system and / or an automated driving system.

[0014] According to the invention, signal transmission between the central unit and a radar transmitter or radar receiver is optical. This is made possible by the co-integration of optical and electrical components for generating and receiving a radar echo signal. The radar driver signal is generated centrally in the central unit and transmitted optically to a radar transmitter or radar receiver. Unlike electrical transmission, optical transmission of the radar driver signal results in low signal attenuation, which makes it possible to supply a large number of radar transmitters and radar receivers with a single radar driver signal.Furthermore, in contrast to electrical lines, phase rigidity (coherence) of the radar driver signal is achieved through optical signal transmission, which enables a particularly simple realization of a distributed radar system with a large number of radar transmitting units and radar receiving units.

[0015] Furthermore, (optical) waveguides are significantly lighter than comparable electrical conductors and less susceptible to external interference, such as electromagnetic fields. The centralized optical generation of the radar driver signal in the central processing unit allows for the compact design and deployment of radar transmitters and receivers. This saves space and reduces costs. Additionally, the complexity of individual radar transmitters and receivers is reduced, making them simple and inexpensive to manufacture and quick and easy to replace in case of a defect.

[0016] According to the invention, the central processing unit and / or the radar receiver unit comprises an optical mixer configured to convert the optical radar echo signal into a different frequency range. In other words, optical mixers can be implemented in the radar system in various ways, namely on the radar receiver unit and / or on the central processing unit. In one implementation, the optical radar echo signal is up- or down-converted in the optical domain of the radar receiver unit, i.e., the frequency of the optical radar echo signal is increased or decreased. In this case, the radar response signal coupled into the waveguide has already been converted into a different frequency range. In an alternative implementation, the optical mixing is performed only by an optical mixer on the central processing unit.In this case, the optical radar response signal coupled into the waveguide is received at its original frequency by the central optical receiver of the central processing unit (CPU). There, the frequency of the optical radar response signal (or the optical radar echo signal contained within it) is up- or down-converted in the optical domain, i.e., the frequency of the optical radar echo signal is increased or decreased. In another implementation, the optical radar echo signal is converted into a different frequency range by an optical mixer on both the radar receiver and the CPU.

[0017] Preferably, the optical radar echo signal is downconverted, meaning the signal frequency is reduced. Downconversion (mixing) in radar systems serves to convert the typically high-frequency radar signal information, usually in the gigahertz range (radio frequency, RF), into a lower sub-gigahertz range (intermediate frequency, IF). While conventional radar systems perform this downconversion in the electrical domain using electronic mixers, optical mixing of the radar echo signal offers several advantages, such as reduced power consumption and space requirements, since no dedicated electronic mixer is needed. Furthermore, an optical implementation of the mixing offers greater flexibility with regard to variable RF carrier frequencies and occupied RF bandwidth compared to purely electronic solutions.

[0018] Unlike RF band detection, optical frequencies oscillate too rapidly to directly measure and electronically process the electric field. Instead, optical photons are preferably detected by absorbing their energy. However, this only captures the magnitude, not the phase, of the electric field. Therefore, the primary purpose of the optical mixer is to convert the radar echo signal from the optical band into an electronically acceptable frequency range, such as a lower-frequency sub-gigahertz range (intermediate frequency, IF), using heterodyne detection. The envelope of the electric field, and in particular the envelope of the radar echo signal, is preferably determined from its magnitude.

[0019] In a preferred embodiment, the optical mixer comprises one or a plurality of optoelectronic components. The optoelectronic component(s) preferably relate to optoelectronic detectors. Examples of optoelectronic detectors include a photoresistor, a photodiode (also a solar cell), and a phototransistor, but also integrated circuits such as CCD sensors. Preferably, the optical mixer comprises one or a plurality of photodiodes. Photodiodes are well-suited as optical mixers because frequency conversion can be easily implemented when converting the optical signal into an electrical signal, if the optical radar driver signal is applied to the photodiode as an auxiliary frequency in the sense of a local oscillator (LO).A local oscillator (LO) is the common term for an oscillator that generates an auxiliary frequency used to modify the transmit or receive frequency via a mixer, thus creating an intermediate frequency (IF). In this context, the optical radar driver signal is used as the auxiliary frequency to convert the radar echo signal to the intermediate frequency. Preferably, the (original) optical radar driver signal is used as the local oscillator. In other words, not just any additional auxiliary frequency is generated and provided to the optical mixer, but rather the optical radar driver signal coupled into the waveguide by the central processing unit. Using the optical radar driver signal as the auxiliary frequency for the optical mixer allows for frequency conversion to the IF range and the determination of the distance to a scanned object based on the frequency.Therefore, no additional local oscillator needs to be used and the (original) radar driver signal can be used immediately to determine the radar information, for example the distance of a scanned object.

[0020] In a further preferred embodiment, the plurality of optoelectronic components comprises a first pair of balanced photodiodes. A pair of balanced photodiodes can be realized by connecting the cathode of one photodiode to the anode of the other. This has the advantage that the direct current (DC) component of the two photodiodes cancels each other out. In other words, balanced photodiodes exhibit intrinsic DC suppression, which simplifies signal processing.

[0021] In a further preferred embodiment, the plurality of optoelectronic components comprises at least a second pair of balanced photodiodes, which is configured as a receiver coherent with the first pair of balanced photodiodes. The optical mixer preferably includes an optical splitter configured to divide the optical radar echo signal into at least two phase-shifted parts and to direct each part of the optical radar echo signal to the pairs of balanced photodiodes. In other words, one part of the two parts of the optical radar echo signal has a phase shift relative to the other part of the optical radar echo signal, so that each pair of balanced photodiodes receives phase-shifted parts of the optical radar echo signal.Understandably, the phase-shifted components are preferably divided again so that a corresponding portion of the optical radar echo signal is provided for each photodiode of the two pairs of balanced photodiodes. By designing the receivers as coherent units and irradiating phase-shifted components of the radar echo signal, signal processing of the radar echo signal with a division into in-phase and quadrature components (I&Q method - in-phase and quadrature method) is possible. This allows the phase information, which preferably includes the phase of the optical radar carrier signal, to be preserved during demodulation of the (high-frequency) radar response signal, for example, to distinguish moving from stationary objects.

[0022] In a further preferred embodiment, the central unit also includes an optical splitter and / or an optical switch. The optical splitter and / or the optical switch are preferably configured to direct the optical radar driver signal, or a portion thereof, to the optical mixer of the central unit. In this case, the optical radar driver signal serves as an auxiliary frequency required for the optical mixer to convert the optical radar echo signal into the intermediate frequency (IF) range. In other words, in this embodiment, the central unit is configured to perform the optical mixing of the radar echo signal. Transmission of the optical radar driver signal from the central unit to the radar receiver is no longer necessary. However, the optical radar driver signal must still be transmitted to the radar transmitter.

[0023] In a further preferred embodiment, the radar receiver unit also includes an optical splitter and / or an optical switch and a further optical modulation unit. The further optical modulation unit is preferably configured to convert the radar echo signal received by the radar receiver into an optical radar echo signal and to provide the optical radar echo signal to the optical mixer. The optical splitter and / or the optical switch of the radar receiver unit are preferably configured to direct the optical radar carrier signal transmitted via the waveguide, or a portion thereof, to the optical mixer of the radar receiver unit and / or to the optical modulation unit. The optical mixer is preferably further configured to electrically supply the optically converted (to a different frequency range) radar echo signal to the optical modulation unit.The optical radar driver signal received by the radar receiver is preferably routed to the optical mixer. In this case, the optical radar driver signal serves as an auxiliary frequency required for the optical mixer to convert the optical radar echo signal into the intermediate frequency (IF) range. In other words, the radar receiver in this configuration is designed to perform the optical mixing of the radar echo signal. Consequently, the radar response signal coupled into the waveguide already includes the radar echo signal converted into the intermediate frequency (IF) range. Therefore, no mixing of the radar echo signal is required on the central processing unit (CPU), thus reducing the complexity of the CPU.

[0024] In a further preferred embodiment, the radar system comprises at least one additional radar transmitter unit, particularly of essentially identical construction, and at least one additional radar receiver unit, particularly of essentially identical construction, each coupled to the central unit via the at least one and / or one additional waveguide. Thus, the radar system preferably comprises a plurality of radar transmitter units, particularly of essentially identical construction, and a plurality of radar receiver units, particularly of essentially identical construction. In other words, the radar system is preferably designed as a distributed radar system. If two or more radar receivers are arranged spatially offset from one another, directional information of the incoming wave can also be determined by evaluating the time-of-flight differences.In other words, the evaluation unit is preferably also configured to determine directional information regarding the target(s) by evaluating the time-of-flight differences. Furthermore, by distributing the radar transmitters and receivers over a large area on the vehicle surface, for example in the form of EPIC chips, and by coherent signal processing of the individual antennas, the resolution can be refined to the desired range of 0.1° (degrees). The maximum distance between the individual radar receivers (antennas) is crucial for the resolution of the radar system. More precisely, it refers to the aperture defined by the radar transmitters and receivers. For example, a resolution of 0.1° (degrees) can be achieved with a distance of 1 m to 1.5 m between two radar receivers on the vehicle surface.If additional radar transmitters and receivers are arranged between the two radar receivers, this does not change the resolution of the radar system, but it does improve signal processing, since this allows the influence of other (undesired) effects contained in the radar echo signal to be factored out. Preferably, the additional radar transmitters and receivers are arranged at a predetermined minimum distance from the radar transmitters and receivers. Preferably, the minimum distance between the antennas is chosen such that a resolution of at least 0.1 degrees is achieved. For example, the minimum distance between at least two of the radar receivers is between 1 m and 1.5 m, preferably between 1.1 m and 1.4 m, and particularly preferably between 1.2 m and 1.3 m.

[0025] In a further preferred embodiment, the radar system also includes at least one line designed for transmitting electrical signals, which is coupled via the central unit to the radar transmitter and / or the radar receiver. The combination of optical lines and additional electrical lines between the central unit and the radar transmitter and / or the radar receiver enables signal transmission using two different transmission technologies, allowing the advantages of both technologies to be exploited, for example, to mitigate the disadvantages of the other. Furthermore, this provides redundant signal transmission. Overall, this increases the reliability of the radar system. Consequently, a more fail-safe radar system is achieved, which is particularly advantageous for autonomous driving.Alternatively, the line designed for transmitting electrical signals preferably serves as a communication interface between the central unit and the radar transmitting and receiving units, for example for parameterization.

[0026] Another aspect of the invention relates to a method for operating a radar system. The radar system is preferably the radar system described above. The advantages achieved with the radar system can be achieved analogously with the method. The disclosed combinations of features of the radar system are transferable to the method by analogy. Therefore, a repetitive description of the features and advantages is omitted.

[0027] According to one process step, an electrical radar ramp signal is generated by a central unit, in particular the central unit mentioned above.

[0028] In a further step of the process, an optical radar carrier signal and an optical radar driver signal are provided by the central unit. The optical radar driver signal is based on the generated electrical radar ramp signal.

[0029] Furthermore, the optical radar carrier signal and the optical radar driver signal are coupled into a waveguide through the central unit.

[0030] In a further process step, the optical radar driver signal coupled into the waveguide is received by a radar transmitter unit and converted by it into an electrical radar driver signal.

[0031] In one step of the process, a radar transmitter of the radar transmission unit is driven by the electrical radar driver signal.

[0032] Furthermore, a radar echo signal, in particular the radar echo signal of the signal emitted by the radar transmitter according to the electrical radar driver signal, is received by a radar receiver of a radar receiving unit.

[0033] In a further process step, an optical radar response signal, which includes an optical radar echo signal generated based on the received radar echo signal, is provided by the radar receiver unit and coupled into the waveguide by it.

[0034] The optical radar response signal coupled into the waveguide is received and evaluated by the central unit.

[0035] Furthermore, the central unit outputs radar information derived from the radar response signal.

[0036] Furthermore, the optical radar echo signal is converted into a different frequency range by an optical mixer in the central unit and / or the radar receiver unit.

[0037] Another aspect of the invention relates to a radar receiving unit for use in the radar system described above. The radar receiving unit is preferably the radar receiving unit described above. The radar receiving unit comprises a radar receiver and an optical modulation unit configured to provide an optical radar response signal, which includes an optical radar echo signal generated based on a radar echo signal received by the radar receiver, and to couple this signal into a waveguide. The radar receiving unit further comprises an optical mixer configured to convert the optical radar echo signal into a different frequency range. The advantages achieved with the radar system can be achieved analogously with the radar receiving unit. The combinations of features of the radar system disclosed with respect to the radar receiving unit are analogously transferable to the radar receiving unit.Therefore, a repetitive description of the features and advantages is omitted.

[0038] Another aspect of the invention relates to a central unit for use in the radar system described above. The central unit is preferably the one mentioned above. The central unit comprises a central optical receiver configured to receive the optical radar response signal coupled into the waveguide, an optical mixer configured to convert the received optical radar response signal into a different frequency range, and an evaluation unit configured to evaluate the received optical radar response signal and output radar information derived therefrom. The advantages achieved with the radar system can be achieved analogously with the central unit. The combinations of features of the radar system disclosed with respect to the central unit are analogously transferable to the central unit. Therefore, a repetitive description of the features and advantages is omitted.

[0039] In a preferred embodiment of the invention, the central unit further comprises a signal generator configured to generate an electrical radar ramp signal and an optical transmitter unit configured to provide an optical radar carrier signal and an optical radar driver signal based on the electrical radar ramp signal generated by the signal generator and to couple these into the at least one waveguide.

[0040] Another aspect of the invention relates to a method for operating the radar receiver unit. The advantages achieved with the radar receiver unit can be achieved analogously with the method. The combinations of features disclosed with respect to the radar receiver unit are transferable to the method by analogy. Therefore, a repetitive description of the features and advantages is omitted.

[0041] According to this method, a radar echo signal is received by the radar receiver, and an optical radar response signal, which comprises an optical radar echo signal generated based on the received radar echo signal, is provided and converted into a different frequency range. Furthermore, the optical radar response signal (converted to the other frequency range) is coupled into a waveguide.

[0042] Another aspect of the invention relates to a method for operating the central processing unit. The advantages achieved with the central processing unit can be achieved analogously with the method. The combinations of features disclosed with respect to the central processing unit are analogously transferable to the method. Therefore, a repetitive description of the features and advantages is omitted.

[0043] In this process, the optical radar response signal coupled into the waveguide is received by the central processing unit (CPU), converted into a different frequency range, and evaluated. Finally, radar information derived from the optical radar response signal is output by the CPU.

[0044] In a preferred embodiment of the invention, an electrical radar ramp signal is generated. Furthermore, an optical radar carrier signal and an optical radar driver signal based on the generated electrical radar ramp signal are provided and coupled into at least one waveguide.

[0045] The individual process steps of the methods according to the invention are preferably configured as one or more processes that run on one or more processors in one or more electronic computing devices and are generated during the execution of one or more computer programs. The computing devices are preferably configured to cooperate with other components in order to realize the functionalities described herein. Likewise, the radar system or individual components, in particular the central processing unit, are preferably configured as central (single-unit) or decentralized (multi-unit) components.

[0046] The individual components of the radar system, in particular the evaluation unit of the central processing unit, are preferably configured, at least partially, as one or more processes running on one or more processors in one or more electronic computing devices and generated during the execution of one or more computer programs. The computing devices are preferably configured to cooperate with other components to implement the functionalities described herein. The instructions of the computer programs are also preferably stored in a memory, such as a RAM element. However, the computer programs can also be stored in a non-volatile storage medium, such as a CD-ROM, flash memory, or the like.

[0047] It is also apparent to those skilled in the art that the functionalities of several computers (data processing devices) can be combined or combined in a single device, or that the functionality of a particular data processing device can be distributed across a multitude of devices in order to carry out the steps of the methods according to the invention without deviating from the methods according to the invention.

[0048] Another aspect of the invention relates to a computer program comprising instructions which, when the program is executed by a computer, cause it to perform at least one of the methods according to the invention.

[0049] The central processing unit and / or the radar receiver preferably also include further electrical and / or optical components. Examples include transimpedance amplifiers and other amplifier devices used to amplify electrical signals, and / or electrical modulators that can be used in signal processing.

[0050] The present invention can be used, in particular, in a motor vehicle for environmental sensing. Exemplary applications include driver assistance systems such as parking assistants, adaptive cruise control, and the like, as well as automatic and / or autonomous driving and the like. In principle, however, the invention can also be used in all fields where radar systems are employed, such as aircraft radar systems, ship radar systems, container terminals, warehouse robot logistics, rail vehicles, military technology, and the like.

[0051] Further preferred embodiments of the invention result from the other features mentioned in the dependent claims.

[0052] Unless otherwise stated in individual cases, the various embodiments of the invention mentioned in this application can be advantageously combined with one another.

[0053] The invention is explained below using exemplary embodiments with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of a radar system according to one embodiment, Fig. 2 a schematic representation of a radar receiver unit according to a first embodiment, Fig. 3 a schematic representation of a radar receiver unit according to a second embodiment, Fig. 4 a schematic representation of a radar receiver unit according to a third embodiment, Fig. 5 a schematic representation of a procedure for operating a radar system according to an implementation form and Fig. 6a-c schematic representations of a motor vehicle with a distributed radar system according to one embodiment.

[0054] Detailed embodiments are now described, illustrated by way of example in the accompanying drawings. The effects and features of these embodiments are described with reference to the accompanying drawings. In the drawings, identical reference numerals denote identical elements, and redundant descriptions are avoided. The present disclosure can be implemented in various forms and is not to be understood as being limited only to the embodiments shown here. Rather, these embodiments are examples to ensure that this disclosure is thorough and complete and fully conveys the aspects and features of the present disclosure to the person skilled in the art.

[0055] Methods, elements, and techniques that are not necessary for a person skilled in the art to fully understand the aspects and features of this disclosure are therefore not described where applicable. In the drawings, the relative sizes of elements, layers, and areas may be exaggerated for clarity.

[0056] As used herein, the term “and / or” includes all combinations of one or more of the elements listed. Furthermore, the use of “may” in the description of embodiments of the present disclosure refers to “one or more embodiments of the present disclosure.” In the following description of embodiments, singular terms may also include the plural unless the context clearly indicates otherwise.

[0057] Although the terms "first" and "second" are used to describe different elements, these elements should not be restricted by these terms. These terms are used only to distinguish one element from another. For example, a first element may be called a second element, and likewise a second element may be called a first element, without this deviating from the scope of the present disclosure. Expressions such as "at least one of," when placed before a list of elements, modify the entire list and not just the individual elements of the list.

[0058] Terms such as "essentially", "approximately", and similar expressions are used as approximations, not as degrees, and are intended to account for the inherent variations in measured or calculated values ​​that are recognized by those skilled in the art. When the term "essentially" is used in conjunction with a characteristic that can be expressed by a numerical value, the term "essentially" means a range of at least + / - 5% of the value centered on that value.

[0059] Fig. Figure 1 shows a schematic representation of a radar system 100 according to one embodiment. For clarity, optical connections and photonic components are generally represented by dashed lines in the figures. The radar system 100 comprises at least one radar transmitter 50, at least one radar receiver 70, a central unit 10, and at least one waveguide 12, which couples the central unit 10 to the radar transmitter 50 and the radar receiver 70. In preferred embodiments, the radar system 100 comprises a plurality of radar transmitters 50, 50', a plurality of radar receivers 70, 70', and a plurality of waveguides 12, 12', as shown in Figure 1. Fig. As indicated in Figure 1, a distributed radar system 100 is present, in which all radar transmitting units 50, 50' are preferably driven centrally by a driver signal provided by the central unit 10. Because the signal transmission is optical via the waveguides 12, 12', it is phase-locked, meaning that no unwanted phase-shifted driver signals reach the radar transmitting units 50, 50' and the radar receiving units 70, 70'.

[0060] The central unit 10 comprises a signal generator 18 configured to generate an electrical radar ramp signal and an optical transmitter unit 20a configured to provide an optical radar carrier signal and an optical radar driver signal based on the electrical radar ramp signal generated by the signal generator 18. Preferably, the optical radar carrier signal (mean optical path in Fig. 1) and the optical radar driver signal (upper optical path in Fig. 1) as (independent) individual signals coupled into the waveguide(s) 12, 12'. The frequency of the optical radar carrier signal is preferably in the THz range. The frequency of the radar ramp signal is preferably in the GHz range. The optical transmitting unit 20a is further configured to couple the optical radar carrier signal and the optical radar driver signal into the at least one waveguide 12, 12' in order to transmit them via the at least one waveguide 12, 12' to the radar transmitting and / or radar receiving units 50, 50', 70, 70'. Understandably, for a (pure) radar transmitting unit 50, 50', it is sufficient if this unit—unlike in Fig. Figure 1 shows the radar receiving (only) the optical radar driver signal. Receiving the optical radar carrier signal by the radar transmitting unit 50, 50' is preferably not strictly necessary.

[0061] The central unit 10 further comprises an evaluation unit 14 and preferably at least one control interface 16, which is connected to the evaluation unit 14 and is configured to control the signal generator 18 such that the signal generator 18 generates a desired radar ramp signal. The signal generator 18 is preferably an analog signal generator and / or a digital signal generator. The signal generator 18 is preferably configured to generate the radar ramp signal as an electrical radar ramp signal and to provide the electrical radar ramp signal to the optical transmitter unit 20a. Although Fig. Figure 1 represents two control interfaces 16; however, the number of control interfaces 16 shown is arbitrary, and the present disclosure is not limited to this. Preferably, one or more than two control interfaces 16 are used. The control interface 16 essentially serves for controlling and / or exchanging signals with the individual electronic and photonic components and is therefore electronically connected to them. Communication for parameterization, diagnostics, and the like between the central unit 10 and the radar receiver 70 is preferably optical and / or electrical.

[0062] The optical transmitter unit 20a preferably comprises a light source, for example a laser diode 22, and / or a modulator, in particular an optical modulator 20. The use of an optical modulator 20 has the advantage that the laser diode 22 itself does not need to be modulated, but only needs to provide the optical radar carrier signal in CW mode. This allows the use of a cost-effective laser diode 22. The laser diode 22 is electrically connected to the control interface 16 for control purposes. Preferably, the optical modulator 20 is configured to change a material property of the waveguide 12 to modulate the optical wave. Preferably, the refractive index and / or the absorption properties of the waveguide 12 are changed.Preferably, the optical modulator 20 is configured to change the material properties of the waveguide 12 by means of charge carriers (current), by means of electric fields (voltage), by means of temperature (heating electrodes) and / or by means of mechanical modification.

[0063] To generate the optical radar carrier signal (mean optical path in Fig. 1) and the optical radar driver signal (upper optical path in Fig. 1) As (independent) individual signals, the optical transmitting unit 20a further preferably comprises an optical divider 26 or an optical switch 26, which is configured to transmit the optical radar carrier signal generated by the laser diode 22 in CW operation via a first optical path to the optical modulator 20 and / or via a second optical path (the middle optical path in Fig. 1) to the waveguide 12, 12'. Alternatively, the central unit 10 comprises two laser diodes 22, each of which shines into one of the two optical paths. In this case, no optical divider 26 or optical switch 26 is required.

[0064] The optical transmitter unit 20a preferably also comprises an optical control unit 24, preferably in the first and / or the second optical path, and / or a further optical divider 28 or optical switch 28 in the first and / or the second optical path. The optical control units 24 are electrically connected to the control interface 16 and are connected in the optical paths between the optical modulator 20 and a (first) optical output (not shown) of the optical transmitter unit 20a or between the optical divider 26 or the optical switch 26 and a (second) optical output (not shown) of the optical transmitter unit 20a. The optical control units 24 are each configured to monitor the amplitude, phase, and / or polarization of the respective passing optical signal and to examine it for (undesired) differences or deviations.In other words, the optical control units 24 each ensure that the output optical signals are correct, as desired. The additional optical dividers 28 or optical switches 28 essentially serve the purpose of controlling the output of the respective optical signals, in particular, in the case of a plurality of radar transmitter units 50, 50' and / or a plurality of radar receiver units 70, 70', to control the correct distribution of the respective optical signals. Preferably, the additional optical dividers 28 or optical switches 28 are connected in the respective optical path between the optical control unit 24 and the optical output (not shown) of the optical transmitter unit 20a.

[0065] The central unit 10 further comprises a central optical receiver 30 configured to receive an optical radar response signal coupled into the waveguide 12. The central optical receiver 30 is configured to convert the optical radar response signal into an electrical radar response signal. Preferably, the optical receiver 30 comprises at least one photodiode. The evaluation unit 14 is configured to evaluate the received optical radar response signal and output radar information derived therefrom (not shown). For this purpose, the evaluation unit 14 is electrically connected to the central optical receiver 30. Preferably, the evaluation unit 14 is configured to perform a frequency analysis by means of a Fourier transform, to determine a (time-of-flight-based) range coordinate of the target(s) and / or its / their Doppler frequency (relative velocity).Preferably, the radar information derived from the optical radar response signal is output to a driver assistance system and / or an automatic driving system.

[0066] The central processing unit 10 preferably comprises an amplifier 32, a signal processing unit 34, an analog-to-digital converter (ADC), and / or a preprocessing unit 38. The amplifier 32 is preferably interposed between the optical receiver 30 and the evaluation unit 14. The signal processing unit 34 is preferably interposed between the optical receiver 30, particularly downstream of the amplifier 32, and the evaluation unit 14. The ADC 36 is preferably interposed between the optical receiver 30, particularly downstream of the signal processing unit 34, and the evaluation unit 14. The preprocessing unit 38 is preferably interposed between the optical receiver 30, particularly downstream of the ADC 36, and the evaluation unit 14. The amplifier 32 is preferably configured to amplify the electrical radar response signal.Examples of amplifiers 32 are transimpedance amplifiers (TIA) and variable-gain amplifiers (VGA). The signal processing unit 34 is preferably configured to process the amplitude and / or phase of the electronic radar response signal and / or to filter the electronic radar response signal. The preprocessing unit 38 is preferably configured to perform a fast Fourier transform (FFT).

[0067] The radar transmitter 50 comprises an optical receiver (not shown) and a radar transmitter (not shown). The optical receiver of the radar transmitter 50 is configured to receive the optical radar driver signal coupled into the waveguide 12 (by the optical transmitter 20a of the central unit 10) and convert it into an electrical radar driver signal. This is preferably done by means of a photodiode. The optical receiver is further configured to provide the (converted) electrical radar driver signal to the radar transmitter (for driving it). For this purpose, the optical receiver is electrically connected to the radar transmitter. In other words, the radar transmitter is enabled to be driven by the electrical radar driver signal in order to transmit a frequency signal with the radar ramp signal (generated in the central unit 10).The frequency signals emitted by the radar transmitter are preferably in the frequency range of 24.05 GHz to 26.65 GHz (according to the radio approval standards for automotive radars ETSI EN 302 858 and ETSI EN 302 288) and / or from 76 GHz to 81 GHz (according to the radio approval standards for automotive radars ETSI EN 301 091 and ETSI EN 302 264).

[0068] According to the invention, the radar driver signal is generated optically and centrally in the central unit 10. Signal transmission between the central unit 10 and the radar transmitter 50, and between the central unit 10 and the radar receiver 70, is also optical. This is made possible by the co-integration of optical and electrical components for generating and receiving a radar echo signal. In contrast to electrical transmission, optical transmission of the radar driver signal results in low signal attenuation, which makes it possible to supply a large number of radar transmitters 50, 50' and radar receivers 70, 70' with a single radar driver signal.Furthermore, in contrast to electrical lines, phase rigidity of the radar driver signal is achieved through optical signal transmission, which enables a particularly simple realization of a distributed radar system 100 with a large number of radar transmitting units 50, 50' and radar receiving units 70, 70'.

[0069] Furthermore, waveguides 12 are significantly lighter than comparable electrical conductors and less susceptible to external interference, such as electromagnetic fields. The centralized optical generation of the radar driver signal in the central unit 10 allows the radar transmitter units 50, 50' and the radar receiver units 70, 70' to be manufactured and provided in a compact design with small dimensions. This saves installation space and costs. Moreover, the complexity of the individual radar transmitter units 50, 50' and individual radar receiver units 70, 70' is reduced, making them easy and inexpensive to manufacture and quick and easy to replace in case of a defect.

[0070] According to the invention, the central unit 10 and / or the radar receiver 70 comprise an optical mixer configured to convert the optical radar echo signal into a different frequency range. In other words, optical mixers can be implemented in the radar system 100 in various ways, namely on the radar receiver 70 and / or on the central unit 10. In one implementation, the optical radar echo signal is up- or down-converted in the optical domain of the radar receiver 70, i.e., the frequency of the optical radar echo signal is increased or decreased. In this case, the radar response signal coupled into the waveguide 12 has already been converted into a different frequency range (see Figure 1). Fig. 4) In an alternative implementation, optical mixing is performed by an optical mixer on the central processing unit 10 (see below). Fig. 2 and Fig. 3) In this case, the optical radar response signal coupled into the waveguide 12 is received with its unchanged frequency by the central optical receiver 30 of the central unit 10, and (only) there is the frequency of the optical radar response signal (or the optical radar echo signal contained therein) up- or down-mixed in the optical domain, i.e., the frequency of the optical radar echo signal is increased or decreased. In another implementation, the optical radar echo signal is converted into a different frequency range by an optical mixer on both the radar receiver 70 and the central unit 10. Preferably, the optical radar echo signal is down-mixed, i.e., the frequency of the signal is reduced. Down-mixing (mixing, downconversion) is used in radar systems 100 to convert the usually common high-frequency radar signal information, typically in the gigahertz range.The radar echo signal is converted from radio frequency (RF) to a lower-frequency sub-gigahertz range (intermediate frequency, IF). In other words, after optical detection, the radar echo signal is optically-to-electrically converted and down-converted to a lower-frequency IF range. While conventional radar systems perform this down-conversion in the electrical domain using electronic mixers, optical mixing of the radar echo signal offers several advantages, such as reduced power consumption and space requirements, as no dedicated electronic mixer is needed. Furthermore, optical mixing provides greater flexibility with regard to variable RF carrier frequencies and occupied RF bandwidth compared to purely electronic solutions.

[0071] Preferably, the optical mixer of the central unit 10 and / or the radar receiver 70 comprises one or a plurality of photodiodes. Photodiodes are well suited as optical mixers because frequency conversion can be easily implemented when converting the optical signal into an electrical signal if the optical radar driver signal is applied to the photodiode as an auxiliary frequency, acting as a local oscillator (LO), to generate an intermediate frequency (IF). Therefore, the optical radar driver signal is preferably used as the auxiliary frequency to convert the radar echo signal to the intermediate frequency. Preferably, the photodiode of the optical receiver 30 can be used directly as the optical mixer.

[0072] With regard to the Fig. 2 to 4 now describe three embodiments of the in Fig. The radar receiver unit 70 shown in section 1 is explained in more detail. Fig. Figure 2 shows a schematic representation of a radar receiver unit 70 according to a first embodiment. Fig. Figure 3 shows a schematic representation of a radar receiver unit 70 according to a second embodiment. Fig. Figure 4 shows a schematic representation of a radar receiver unit 70 according to a third embodiment.

[0073] The first two embodiments of the radar receiver 70 are not capable of converting a received radar echo signal (optically) into a different frequency range, for example, by downmixing it. In these embodiments, the central unit 10 includes an optical mixer configured to convert the received radar echo signal into a different frequency range. The radar receiver 70 according to the third embodiment, however, includes its own optical mixer configured to convert a received radar echo signal into a different frequency range. Therefore, an optical mixer on the central unit 10 is not strictly necessary in this embodiment (but is possible).

[0074] As in Fig. As shown in Figure 2, the radar receiving unit 70 according to the first embodiment comprises a radar receiver 72 and an optical modulation unit 80, which is configured to provide an optical radar response signal comprising a radar echo signal received via the radar receiver 72 and the optical radar carrier signal coupled in via the waveguide 12 by the central unit 10, and to couple this signal into the waveguide 12. In other words, the radar echo to the frequency signal transmitted by the radar transmitter according to the radar ramp signal is received by the radar receiver 72 and provided as an electrical radar echo signal to the optical modulation unit 80.The optical modulation unit 80 is configured to modulate the received radar echo signal onto the optical radar carrier signal received by the central unit 10 via the waveguide 12 in order to generate the optical radar response signal, which is transmitted to the central unit 10 via the waveguide 12. Preferably, the received (electrical) radar echo signal is amplified (with respect to its amplitude) by a low-noise amplifier 74 and a further amplifier 76 of the radar receiver 70 and fed to a signal processing unit 78 of the radar receiver 70. The signal processing unit 78 is preferably configured to process the amplitude and / or the phase of the electronic radar echo signal and / or to filter the electronic radar echo signal and then provide it to the optical modulation unit 80.The radar receiver 70 preferably further comprises an optical control unit 82 in each of an optical input path and an optical output path. The optical control units 82 are each configured to monitor the amplitude, phase, and / or polarization of the respective optical signal and to examine it for (undesired) differences or deviations. In other words, the optical control units 82 ensure that the optical signals are correct, as desired. For controlling the electronic and photonic components, the radar receiver 70 comprises two control interfaces 84. Although... Fig. Figure 2 represents two control interfaces 84. The number of control interfaces 84 shown is arbitrary, and the present disclosure is not limited to this. Preferably, one or more than two control interfaces 84 are used. The control interface 84 essentially serves to control and / or exchange signals with the individual electronic and photonic components and is therefore electronically connected to them. In preferred embodiments, the control interface 84 is further configured for the electronic and / or photonic exchange of signals with the central processing unit 10.

[0075] Since the radar response signal coupled into the waveguide 12 by the radar receiver unit 70 according to the first embodiment comprises the received radar echo signal and the optical radar carrier signal, but not the optical radar driver signal, the optical transmitter unit 20a of the central unit 10 for this embodiment of the radar receiver unit 70 preferably comprises a further optical splitter 29 or optical divider 29 in the first optical path (see Fig. 1), which are configured to direct the optical radar driver signal via the first optical path to the optical output (not shown) and / or to the central optical receiving unit 30.

[0076] With regard to Fig. Section 3 explains in more detail the radar receiver 70 according to the second embodiment. A description of the radar receiver 70 according to the first embodiment, already given in Section 3, is omitted. Fig. The two described features are omitted. Only the differences are explained in more detail below.

[0077] The radar receiving unit 70 according to the second embodiment further comprises a combiner 86 and a second optical input path (middle optical input path in Fig. 3) furthermore, to receive the radar driver signal coupled into the waveguide 12 by the central unit 10 and to direct it to the combiner 86. An optical control unit 82 is preferably provided in the second optical input path.

[0078] The combiner 86 is arranged in the optical output path between the optical modulation unit 80 and the output of the optical output path, in particular upstream of the optical control unit 82. The combiner 86 is configured to combine the optical radar response signal generated by the optical modulation unit 80 with the optical radar driver signal and to couple this combination into the waveguide 12.

[0079] Since the radar response signal coupled into the waveguide 12 by the radar receiver 70 according to the second embodiment comprises the received radar echo signal, the optical radar carrier signal and the optical radar driver signal, no optical divider 29 or optical switch 29 is required in the first optical path of the central unit 10 to convert the radar response signal to a different frequency range by the optical mixer on the central unit 10.

[0080] With regard to Fig. Section 4 explains in more detail the radar receiver 70 according to the third embodiment. A description of the radar receiver 70 according to the second embodiment, already given in Section 4, is omitted. Fig. The three described features are omitted. Only the differences are explained in more detail below.

[0081] The radar receiver 70 according to the third embodiment further comprises an optical splitter 88 and / or an optical switch 88, an optical receiver 90, and a further optical modulation unit 92. The further optical modulation unit 92 is preferably configured to convert the radar echo signal received via the radar receiver 72 into an optical radar echo signal and to provide the optical radar echo signal to the optical receiver 90 (via the combiner 86). The optical splitter 88 and / or the optical switch 88 of the radar receiver 70 are preferably configured to direct the optical radar carrier signal transmitted via the waveguide 12, or a portion thereof, to the optical receiver 90 of the radar receiver 70 and / or to the optical modulation unit 80. Preferably, the optical radar carrier signal is directed from the optical splitter 88 and / or the optical switch 88 to the further optical modulation unit 92.

[0082] The optical receiver 90 preferably comprises a photodiode used as an optical mixer. The optical mixer is preferably further configured to provide the optically converted (to a different frequency range) radar echo signal to the optical modulation unit 80. The converted radar echo signal is then available to the optical modulation unit 80 as an electrical signal. The optical radar driver signal received by the radar receiver 70 is preferably routed to the optical mixer. In this case, the optical radar driver signal serves as an auxiliary frequency required for the optical mixer to convert the optical radar echo signal into the intermediate frequency (IF) range. In other words, the radar receiver 70 in this configuration is designed to perform the optical mixing of the radar echo signal.Consequently, the radar response signal coupled into the waveguide 12 already includes the radar echo signal converted into the intermediate frequency (IF) range. Therefore, no mixing of the radar echo signal is required on the central processing unit 10, thus reducing the complexity of the central processing unit 10.

[0083] Fig. Figure 5 shows a schematic representation of a method for operating a radar system 100, in particular the one above, according to an implementation form.

[0084] In a first process step 102, an electrical radar ramp signal is generated by a central unit 10.

[0085] According to a second process step 104, an optical radar carrier signal and an optical radar driver signal based on the generated electrical radar ramp signal are provided by the central unit 10.

[0086] Furthermore, the optical radar driver signal and the optical radar driver signal are coupled into a waveguide 12 by the central unit 10 (third process step 106).

[0087] In a fourth process step 108, the optical radar driver signal coupled into the waveguide 12 is received by a radar transmitter unit 50 and converted by this unit into an electrical radar driver signal.

[0088] According to a fifth process step 110, a radar transmitter of the radar transmitting unit 50 is driven by the electrical radar driver signal.

[0089] Furthermore, a radar echo signal is received by a radar receiver 72 of a radar receiving unit 70 (sixth process step 112).

[0090] In a seventh process step 114, an optical radar response signal, which includes an optical radar echo signal generated on the basis of the received radar echo signal, is provided by the radar receiver unit 70 and coupled into the waveguide 12 by it.

[0091] According to an eighth process step 116, the optical radar response signal coupled into the waveguide 12 is received by the central unit 10 and evaluated by it.

[0092] Furthermore, radar information derived from the radar response signal is output by the central unit 10 (ninth process step 118).

[0093] Furthermore, the optical radar echo signal is converted into a different frequency range by an optical mixer of the central unit 10 and / or the radar receiver unit 70.

[0094] The Fig. Figures 6a-c show various schematic representations of a motor vehicle with a distributed radar system 100 according to one embodiment. Fig. Figure 6a shows the motor vehicle in a frontal view, Fig. 6b shows the motor vehicle in a rear view and Fig. Figure 6c shows the motor vehicle in a side view.

[0095] The distributed radar system 100 comprises a multitude of radar transmitting units 50, 50' and a multitude of radar receiving units 70, 70', which are distributed along various side surfaces of the vehicle. In other words, the Fig. 6a-c describes a possible integration of the (photonic) radar system 100 into a motor vehicle. For example, the windshield, rear window and / or bumper can be used for integration into the front and / or rear of the vehicle, and the vehicle floor, roof and / or B-pillar for integration on the sides of the vehicle.

[0096] Among other things, the following advantages result: co-integration of EPIC processes (EPIC - electronic-photonic integrated circuit) in SiGe, SiN, CMOS, hybrid-BiCMOS processes and similar materials, cost savings, reduced installation space, increased flexibility with respect to variable RF carrier frequency and RF bandwidth compared to electronic solutions and the like.Furthermore, simple hardware-based signal generation with low noise and low phase noise, a large range of unique distance measurements and thus avoidance of over-range, unambiguous recognition of the transmitter's own signal at the receiver through coding, the possibility of simultaneous transmission of multiple measurement signals from multiple transmitting antennas and unambiguous recovery at the receiver, reduced computational effort in signal processing, energy savings for signal processing, and / or use in electronic-photonic, photonic, and electronic semiconductor circuits for use in photonic radar systems are possible. The methods described herein can be applied to LiDAR, camera, and satellite communication systems in both civilian and military applications. Reference symbol list 10 Central processing unit 12, 12' waveguide 14 evaluation units 16 Control interface 18 Signal generator 20a optical transmitter unit 20 optical modulators 22 Laser diode 24 optical control unit 26 optical divider / optical switch 28 optical dividers / optical switches 29 optical divider / optical switch 30 central optical receiving units 32 amplifiers 34 Signal processing unit 36 ADC converters 38 Pre-processing unit 50 radar transmitter units 50' additional radar transmitter unit 70 Radar receiver unit 70' additional radar receiver unit 72 radar receivers 74 low-noise amplifier 76 amplifiers 78 Signal processing unit 80 optical modulation units 82 optical control unit 84 Control interface 86 Combinator 88 optical divider / optical switch 90 optical receiving unit 92 additional optical modulation units 100 radar systems 102 First procedure step - Generating radar ramp signal 104 Second procedure step - Providing optical radar driver signal 106 Third process step - Coupling optical radar driver signal 108 Fourth process step - Receiving and converting radar driver signal 110 fifth process step - driving radar transmitter 112 sixth procedure step - Receiving radar echo signal 114 Seventh procedure step - Providing and coupling radar response signal 116 Eighth procedural step - Receiving and evaluating 118 Ninth procedural step - Output radar information QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 221 257 A1

[0005] Cited non-patent literature

[0000] ETSI EN 302 858

[0067] ETSI EN 302 288

[0067] ETSI EN 301 091

[0067] ETSI EN 302 264

[0067]

Claims

[1] Radar system (100), comprising: - at least one radar transmitting unit (50) with an optical receiving unit and a radar transmitter, - at least one radar receiving unit (70) with a radar receiver (72) and an optical modulation unit (80) and - a central unit (10) coupled to the radar transmitting unit (50) and the radar receiving unit (70) via at least one waveguide (12), wherein the central unit (10) comprises a signal generator (18) configured to generate an electrical radar ramp signal and an optical transmitting unit (20a) configured to provide an optical radar carrier signal and an optical radar driver signal based on the electrical radar ramp signal generated by the signal generator (18) and to couple these into the at least one waveguide (12), wherein the optical receiving unit of the radar transmitting unit (50) is configured to receive the optical radar driver signal coupled into the waveguide (12) and to convert it into an electrical radar driver signal and to provide the electrical radar driver signal to the radar transmitter, wherein the optical modulation unit (80) of the radar receiver unit (70) is configured to provide an optical radar response signal, which comprises an optical radar echo signal generated on the basis of a radar echo signal received via the radar receiver (72), and to couple this signal into the waveguide (12), wherein the central unit (10) further comprises a central optical receiver unit (30) configured to receive the optical radar response signal coupled into the waveguide (12) and an evaluation unit (14) configured to evaluate the received optical radar response signal and to output radar information derived therefrom, and wherein the central unit (10) and / or the radar receiving unit (70) comprises an optical mixer configured to convert the optical radar echo signal into a different frequency range. [2] Radar system (100) according to claim 1, wherein the optical mixer comprises one or a plurality of optoelectronic components. [3] Radar system (100) according to claim 2, wherein the plurality of optoelectronic components comprises a first pair of balanced photodiodes. [4] Radar system (100) according to claim 3, wherein the plurality of optoelectronic components comprises a second pair of balanced photodiodes, which is configured as a receiver coherent to the first pair of balanced photodiodes, wherein the optical mixer has an optical divider which is configured to divide the optical radar echo signal into at least two parts that are out of phase with each other and to direct each part of the optical radar echo signal to the pairs of balanced photodiodes. [5] Radar system (100) according to one of the preceding claims, wherein the central unit (10) further comprises an optical splitter (29) and / or an optical switch (29), wherein the optical splitter (29) and / or the optical switch (29) are configured to direct the optical radar driver signal or a part thereof to the optical mixer of the central unit (10). [6] Radar system (100) according to one of the preceding claims, wherein the radar receiver unit (70) further comprises an optical splitter (88) and / or an optical switch (88) and a further optical modulation unit (92) which is configured to convert the radar echo signal received via the radar receiver (72) into an optical radar echo signal and to provide the optical radar echo signal to the optical mixer, wherein the optical divider (88) and / or the optical switch (88) of the radar receiver (70) are configured to direct the optical radar carrier signal transmitted via the waveguide (12) or a part thereof to the optical mixer of the radar receiver (70) and / or to the optical modulation unit (80) and wherein the optical mixer is further configured to electrically supply the optically converted radar echo signal to the optical modulation unit (80). [7] Radar system (100) according to any one of the preceding claims, further comprising: - at least one additional radar transmitter unit (50') and - at least one further radar receiving unit (70'), each coupled to the central unit (10) via at least one and / or one further waveguide (12'). [8] Method for operating a radar system (100), comprising the steps: - Generating (102) an electrical radar ramp signal by a central unit (10), - Providing (104) an optical radar carrier signal and an optical radar driver signal based on the electrical radar ramp signal generated by the central unit (10), - Coupling (106) of the optical radar carrier signal and the optical radar driver signal into a waveguide (12) by the central unit (10), - Receiving and converting (108) the optical radar driver signal coupled into the waveguide (12) into an electrical radar driver signal by a radar transmitting unit (50), - Driving (110) a radar transmitter of the radar transmitting unit (50) with the electrical radar driver signal, - Receiving (112) a radar echo signal with a radar receiver (72) of a radar receiving unit (70), - Providing and coupling (114) an optical radar response signal, comprising an optical radar echo signal generated based on the received radar echo signal, into the waveguide (12) by the radar receiver unit (70), - Receiving and evaluating (116) the optical radar response signal coupled into the waveguide (12) by the central unit (10) and - Output (118) of radar information derived from the radar response signal by the central unit (10), wherein the optical radar echo signal is converted into a different frequency range by an optical mixer of the central unit (10) and / or the radar receiving unit (70). [9] Radar receiving unit (70) for use in a radar system (100) according to any one of claims 1 to 7, comprising: - a radar receiver (72), - an optical modulation unit (80) configured to provide an optical radar response signal comprising an optical radar echo signal generated based on a radar echo signal received via the radar receiver (72), and to couple this signal into the waveguide (12), and - an optical mixer designed to convert the optical radar echo signal into a different frequency range. [10] Central unit (10) for use in a radar system (100) according to any one of claims 1 to 7, comprising: - a central optical receiving unit (30) designed to receive the optical radar response signal coupled into the waveguide (12), - an optical mixer configured to convert the received optical radar response signal into a different frequency range, and - an evaluation unit (14) which is configured to evaluate the optical radar response signal converted into a different frequency range and to output radar information derived therefrom. [11] Central processing unit (10) according to claim 10, further comprising: - a signal generator (18) designed to generate an electrical radar ramp signal and - an optical transmitting unit (20a) configured to provide an optical radar carrier signal and an optical radar driver signal based on the electrical radar ramp signal generated by the signal generator (18) and to couple these into the at least one waveguide (12). [12] Method for operating a radar receiving unit (70) according to claim 9, comprising the steps: - Receiving (112) a radar echo signal with the radar receiving unit (70) and - Providing and converting (114) an optical radar response signal, comprising an optical radar echo signal generated on the basis of the received radar echo signal, into a different frequency range and coupling it into a waveguide (12). [13] Method for operating a central processing unit (10) according to claim 10 or 11, comprising the steps: - Receiving (116) and converting the optical radar response signal coupled into the waveguide (12) into a different frequency range and evaluating it, - Output (118) radar information derived from the optical radar response signal. [14] The method of claim 13, further comprising the steps of: - Generating (102) an electrical radar ramp signal, - Providing (104) an optical radar carrier signal and an optical radar driver signal based on the generated electrical radar ramp signal, and - Coupling (106) the optical radar carrier signal and the optical radar driver signal into at least one waveguide (12).

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