Radar system, method for operating a radar system, radar reception unit, 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). The invention further relates to a radar receiving unit (70) and a central unit (10) of such a radar system (100). The invention further relates to a method for operating a radar receiving unit (70) and to a method for operating a central unit (10). According to the invention, a radar echo signal received by the radar system (100) is converted into another frequency range by means of the optical mixer. Optical mixing of radar echo signals has the advantage of reduced power consumption and space requirements compared to electronic mixers.

Description

Technical Field

[0001] This invention relates to a radar system and a method for operating the radar system. Furthermore, this invention relates to a radar receiving unit and a central unit of such a radar system. Additionally, this invention relates to a method for operating a radar receiving unit and a method for operating a central unit. Background Technology

[0002] For autonomous driving of motor vehicles, reliable environmental perception is crucial. Modern vehicles utilize environmental sensors such as radar, LiDAR, and cameras to acquire the vehicle's environment. The focus is on comprehensive 360°-3D environmental acquisition, capturing as many static and dynamic objects as possible within the vehicle's environment. LiDAR technology, in particular, is well-suited for redundant and robust environmental acquisition because this sensor type can be accurately used for environmental acquisition, distance measurement, and object classification. However, this type of sensor is cost-intensive and structurally complex. In particular, 360°-3D environmental acquisition using LiDAR technology is problematic because it requires either many small individual sensors (which typically operate with multiple individual light source and detector elements) or expensive large sensors to ensure this comprehensive environmental acquisition. Furthermore, LiDAR systems are known to be susceptible to weather conditions such as rain, fog, or direct sunlight. This weather dependence, in particular, makes reliable environmental acquisition using LiDAR systems difficult.

[0003] Radar sensors have been established in the automotive industry for many years, providing reliable and trouble-free data in all weather conditions. Even in poor visibility conditions such as rain, fog, snow, dust, and darkness, their perception reliability remains virtually unaffected. However, their resolution—compared to LiDAR sensors—is severely limited. Radar installed in modern vehicles typically achieves a resolution of up to about 5° (angle). However, to meet the requirements of Level 4 and / or Level 5 autonomous driving with safe driving functions, radar sensors must provide three-dimensional images with fine resolution within a 0.1° (angle) range, and even more finely, with greater insensitivity to interference from their surroundings. This cannot be achieved using conventional radar technology due to the excessively low resolution of existing systems.

[0004] Current developments in photonic radar systems focus on the co-integration of electronic and photonic components within a single semiconductor. The generation of the FMCW signal, as well as the entire signal processing and evaluation, is performed by a central station. The transmitting and receiving modules consist of an electro-photonic co-integrated chip (the so-called "EPIC chip"). For this co-integration, silicon photonics technology is used. This technology enables the monolithic integration of photonic structural elements, high-frequency electronic devices, and digital electronic devices onto a single chip ("electro-photonic co-integration").

[0005] An example of a photonic radar system is disclosed in document DE 10 2017 221 257 A1. Here, a GHz signal is transmitted using an optical carrier signal in the THz frequency range. The signal to be transmitted is modulated onto the optical carrier signal generated by a central station at, for example, 1 / 8 of the radar frequency, and transmitted to an antenna chip via optical fiber. On the antenna chip, the frequency is amplified by eight times, allowing radiation to be emitted from the antenna chip in its original form. Signal detection is then performed accordingly on the reverse path.

[0006] In photonic radar systems, signals in the GHz range need to be down-mixed to the sub-GHz range. Compared to HF band detection, optical frequency oscillations are too fast for direct measurement and electronic processing of the electric field. Therefore, in traditional radar systems, down-mixing of radar echo signals is performed using dedicated electronic circuitry (mixers). However, electronic mixers increase power consumption and require a larger chip area. Summary of the Invention

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

[0008] The objective according to the invention is achieved by the radar system according to the invention and the method for operating the radar system.

[0009] The first aspect relates to a (photonic) radar system. The radar system includes at least one radar transmitting unit, at least one radar receiving unit, and a central unit coupled to both the radar transmitting unit and the radar receiving unit via at least one (optical) waveguide. Preferably, the central unit is coupled to the radar transmitting unit via a first waveguide and to the radar receiving unit via a second waveguide. Alternatively or additionally, the radar transmitting unit and the radar receiving unit are coupled to the central unit via the same waveguide. Preferably, optical fiber (e.g., glass fiber) is used as the waveguide.

[0010] The central unit includes a signal generator for generating an electric radar ramp signal and an optical transmission unit configured to provide an optical radar carrier signal and an optical radar drive signal based on the electric radar ramp signal generated by the signal generator. The optical radar carrier signal and the optical radar drive signal are preferably coupled as (independent) single signals to one or more waveguides. In another embodiment, the optical radar drive signal is applied to the optical radar carrier signal. In other words, the optical transmission unit is preferably configured to modulate the electric 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 vary within a specific frequency range (frequency-modulated radar, FMCW). Therefore, 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 transmission unit is also configured to couple the optical radar carrier signal and the optical radar drive signal to at least one waveguide. In other words, the central unit provides an optical radar drive signal containing a preset or pre-defined radar ramp signal, which is transmitted via a waveguide to the radar transmitting unit and the radar receiving unit. The optical transmitting unit preferably includes a laser diode and / or a modulator, particularly an optical modulator. Using a modulator has the advantage that the laser diode itself does not need to be modulated, but only needs to provide an optical carrier signal in CW (Continuous Wave) operation. This allows the use of cost-effective laser diodes. 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, particularly preferably 1310 nm and / or 1550 nm. The signal generator is preferably configured to generate a radar ramp signal as an electric radar ramp signal and provide the electric radar ramp signal to the optical transmitting unit.

[0011] The radar transmitting unit includes an optical receiving unit and a radar transmitter. The optical receiving unit of the radar transmitting unit is configured to receive an optical radar drive signal coupled into the waveguide (by the optical transmitting unit of the central unit) and convert it into an electric radar drive signal. Preferably, the optical receiving unit of the radar transmitting unit is configured to receive an optical radar carrier signal coupled into the waveguide (by the optical transmitting unit of the central unit). The optical receiving unit is also configured to provide the (converted) electric radar drive signal to the radar transmitter (to drive the radar transmitter). In other words, the radar transmitter can be manipulated using the electric radar drive signal to emit a frequency signal having a radar ramp signal (generated in the central unit). The optical receiving unit is preferably a photodiode. Photodiodes are well-suited for converting optical radar drive signals into electric radar drive signals.

[0012] The radar receiving unit includes a radar receiver and an optical modulation unit configured to provide and couple an optical radar response signal into a waveguide. The optical radar response signal includes an optical radar echo signal generated based on a radar echo signal received via the radar receiver and, preferably, an optical radar drive signal. In other words, the radar receiver receives the radar echo against a frequency signal emitted by the radar transmitter according to a radar ramp signal and provides it as an electrical radar echo signal to the optical modulation unit. The radar echo signal is a time-off copy of the optical radar drive signal, depending on the target distance. Therefore, the optical modulation unit is configured to convert the received electrical radar echo signal into an optical radar echo signal and couple it 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 modulate it onto the optical radar drive signal received by the central unit via the waveguide to generate an optical radar response signal transmitted via the waveguide to the central unit. In other words, the optical radar response signal to be coupled into the waveguide may (only) include the optical radar echo signal, or it may already include the radar echo signal modulated onto the optical radar carrier signal. In the first case, the radar receiver unit can therefore be manufactured and supplied in a compact form with a small size. This saves structural space and cost. In the second case, the signal processing portion has been extended from the central unit to the radar receiver unit. This can be particularly advantageous for distributed radar systems with a large number of radar transmitters and receivers (which communicate with the central unit via waveguides respectively), since the central unit then receives the pre-processed signal from the radar receiver unit.

[0013] The central unit also includes a central optical receiving unit for receiving the optical radar response signal coupled to the waveguide, and an evaluation unit configured to evaluate the received optical radar response signal and output radar information derived therefrom. The evaluation unit is preferably configured to perform frequency analysis via Fourier transform, and thus determine the (time-based) range coordinates and Doppler frequencies (relative velocities) of one or more targets. For example, in the receiving channel of the central unit, the range coordinates of the targets can be determined by cross-correlating the radar response signal with the radar drive 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 constructed spatially offset from each other, the direction information of the incident wave can also be determined by evaluating the propagation time difference. The radar information derived from the optical radar response signal is preferably output to a driver assistance system and / or an autonomous driving system.

[0014] According to the present invention, signal transmission from the central unit and the radar transmitting unit or radar receiving unit is performed optically. This is achieved through the co-integration of optical and electrical components for generating and receiving radar echo signals. The generation of radar drive signals is centrally performed in the central unit, and transmission to the radar transmitting unit or radar receiving unit is performed optically. Compared with electrical transmission, less signal attenuation occurs in the optical transmission of radar drive signals, enabling the joint supply of radar drive signals to a large number of radar transmitting units and radar receiving units. Furthermore, compared with electrical circuits, the phase-locked loop (coherence) of the radar drive signals is achieved through optical signal transmission, which makes it particularly easy to implement a distributed radar system with multiple radar transmitting units and radar receiving units.

[0015] Furthermore, (optical) waveguides are significantly lighter than corresponding electrical circuits and less sensitive to external interference (such as electromagnetic fields). By centrally generating radar drive signals optically in a central unit, radar transmitting and receiving units can be manufactured and provided in a compact structure with a small size. This saves structural space and cost. Moreover, the complexity of individual radar transmitting or receiving units is reduced, allowing them to be manufactured simply and economically, and to be easily and quickly replaced in case of failure.

[0016] According to the invention, the central unit and / or radar receiving unit further include an optical mixer configured to convert the optical radar echo signal to another frequency range. In other words, the optical mixer can be implemented in various ways in the radar system, i.e., on the radar receiving unit and / or the central unit. In one implementation, the optical radar echo signal is up-mixed or down-mixed in the optical domain at the radar receiving unit, i.e., the frequency of the optical radar echo signal is increased or decreased. In the mentioned case, the radar response signal coupled to the waveguide has already been converted to another frequency range. In an alternative implementation, optical mixing is performed only by an optical mixer on the central unit. In this case, the optical radar response signal coupled to the waveguide is received at its original frequency by the central optical receiving unit of the central unit, and there, the frequency of the optical radar response signal (or the optical radar echo signal contained therein) is up-mixed 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 to another frequency range by optical mixers on the radar receiving unit and the central unit, respectively.

[0017] Preferably, the optical radar echo signal is down-mixed, meaning the signal frequency is reduced. In radar systems, down-mixing is used to convert the most common high-frequency radar signal information (typically in the gigahertz range, radio frequency, RF) to a lower sub-gigahertz range (intermediate frequency, IF). Conventional radar systems implement this down-mixing in the electrical domain using electronic mixers, while optical mixing of the radar echo signal offers various advantages, such as reduced power consumption and space requirements, as no dedicated electronic mixer is needed. Furthermore, compared to purely electronic solutions, the optical implementation of mixing offers increased flexibility relative to variable RF carrier frequencies and occupied RF bandwidth.

[0018] Compared to HF band detection, optical frequency oscillations are too rapid for direct measurement and electronic processing of the electric field. Instead, photons are preferably acquired by absorbing photon energy. However, this only yields the magnitude of the electric field, not its phase. Therefore, the primary purpose of an optical mixer is to convert the radar echo signal from the optical band to an electronically acceptable frequency range, such as the lower sub-gigahertz range (IF), using heterodyne mixing (differential detection). The envelope, particularly the envelope of the radar echo signal, is preferably determined based on the magnitude of the electric field.

[0019] In a preferred design, the optical mixer comprises one or more optoelectronic components. These optoelectronic components preferably relate to photodetectors. Examples of photodetectors are photoresistors, photodiodes (also solar cells), and phototransistors, but also integrated circuits such as CCD sensors. The optical mixer preferably comprises one or more photodiodes. Photodiodes are well-suited for use in optical mixers because frequency conversion can be easily achieved by directing the optical radar drive signal as an auxiliary frequency (LO) onto the photodiode when converting an optical signal into an electrical signal. A local oscillator or local oscillator (LO) is typically the name for an oscillator that generates an auxiliary frequency used by the mixer to change the transmit or receive frequency, thus resulting in an intermediate frequency (IF). In this context, the optical radar drive signal is used as an auxiliary frequency to convert the radar echo signal to the IF. Preferably, the (original) optical radar drive signal is used as the local oscillator. In other words, instead of generating an additional auxiliary frequency and supplying it to the optical mixer, the optical radar drive signal is coupled to the waveguide by the central unit. Using the optical radar drive signal as an auxiliary frequency for the optical mixer allows for frequency conversion to the IF range and correlation between the frequency and the distance to the scanned object. In this respect, there is no need to use an additional local oscillator, and the (raw) radar drive signal can be used immediately to determine radar information, such as the distance to the scanned object.

[0020] In another preferred design, the multiple optoelectronic components include a first pair of balanced photodiodes. A pair of balanced photodiodes can be achieved by connecting the cathode of one photodiode to the anode of another. This has the advantage that the DC-direct current components of the two photodiodes cancel each other out. In other words, the balanced photodiodes have inherent DC suppression, thereby simplifying signal processing.

[0021] In another preferred design, the plurality of optoelectronic components include at least a second pair of balanced photodiodes designed as coherent receivers with the first pair of balanced photodiodes. The optical mixer preferably has an optical splitter configured to divide the optical radar echo signal into at least two mutually phase-shifted portions, and to direct a portion of the optical radar echo signal to each pair of balanced photodiodes, respectively. In other words, one portion of the two portions of the optical radar echo signal is phase-shifted from the other portion, such that each pair of balanced photodiodes receives the mutually phase-shifted portion of the optical radar echo signal. Understandably, the mutually phase-shifted portions are preferably re-divided, thus providing a corresponding portion of the optical radar echo signal for each of the two pairs of balanced photodiodes. By designing itself as a coherent receiver and receiving the phase-shifted portion of the radar echo signal, signal processing can be performed on the radar echo signal, wherein it is divided into in-phase and quadrature components (I&Q method, in-phase & quadrature method). Thus, phase information (preferably including the phase of the optical radar carrier signal) can be obtained from the demodulation of the (high-frequency) radar response signal, for example, so that moving objects and non-moving objects can be distinguished.

[0022] In another preferred design, the central unit further includes an optical splitter and / or an optical switch. The optical splitter and / or optical switch are preferably configured to direct the optical radar drive signal, or a portion thereof, to an optical mixer in the central unit. In this case, the optical radar drive signal serves as an auxiliary frequency required to convert the optical radar echo signal to the intermediate frequency range (IF range) via the optical mixer. In other words, in this design, the central unit is configured to perform optical mixing of the radar echo signal. Here, it is (no longer) necessary to transmit the optical radar drive signal from the central unit to the radar receiving unit. However, the optical radar drive signal must still be transmitted to the radar transmitting unit.

[0023] In another preferred design, the radar receiving unit further includes an optical splitter and / or optical switch and an additional optical modulation unit. This additional optical modulation unit is preferably configured to convert the radar echo signal received via the radar receiver into an optical radar echo signal and provide this optical radar echo signal to an optical mixer. The optical splitter and / or optical switch of the radar receiving unit is preferably configured to guide an optical radar carrier signal, or a portion thereof, transmitted via a waveguide to the optical mixer and / or optical modulation unit of the radar receiving unit. The optical mixer is preferably further configured to provide the optically converted (to another frequency range) radar echo signal electrically to the optical modulation unit. The optical radar drive signal received by the radar receiving unit is preferably guided to the optical mixer. In this case, the optical radar drive signal serves as an auxiliary frequency required for converting the optical radar echo signal to the intermediate frequency range (IF range) via the optical mixer. In other words, in this design, the radar receiving unit is configured to perform optical mixing of the radar echo signal. Therefore, the radar response signal coupled into the waveguide already includes the radar echo signal converted to the intermediate frequency range (IF range). Thus, there is no need for mixing the radar echo signal in the central element, thereby reducing the complexity of the central element.

[0024] In another preferred design, the radar system further includes at least one additional, particularly substantially identical, radar transmitting unit and at least one additional, particularly substantially identical, radar receiving unit, each coupled to the central unit via at least one and / or additional waveguides. Therefore, the radar system preferably includes multiple, particularly substantially identical, radar transmitting units and multiple, particularly substantially identical, radar receiving units. 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 each other, the direction information of the incident wave can also be determined by evaluating the propagation time difference. In other words, the evaluation unit is preferably also configured to determine the direction information about one or more targets by evaluating the propagation time difference. Furthermore, by distributing the radar transmitting and receiving units (e.g., in the form of EPIC chips) over a large area on the vehicle surface and performing coherent signal processing on each antenna, the resolution can be refined to a desired range of 0.1° (angle). For the resolution of the radar system, the maximum distance between the individual radar receivers (antennas) is crucial. More precisely, this refers to the aperture created by the radar transmitting and receiving units. For example, a resolution of 0.1° (angle) can be achieved when the distance between two radar receivers on the vehicle surface is 1m to 1.5m. Arranging additional radar transmitting and receiving units between the two radar receivers does not change the resolution of the radar system, but improves signal processing because it allows the calculation of additional (undesired) effects contained in the radar echo signal. The additional radar transmitting and receiving units are preferably arranged at a predetermined minimum distance from the radar transmitting and receiving units. Preferably, the minimum distance between the antennas is selected such that a resolution of at least 0.1° (angle) is achieved. For example, the minimum distance between at least two of the radar receivers is between 1m and 1.5m, preferably between 1.1m and 1.4m, and particularly preferably between 1.2m and 1.3m.

[0025] In another preferred design, the radar system further includes at least one line for transmitting electrical signals, which is coupled to a radar transmitting unit and / or a radar receiving unit via a central unit. The combination of optical and additional electrical lines between the central unit and the radar transmitting and / or receiving units enables signal transmission using two different transmission technologies, thereby fully utilizing the advantages of both technologies to, for example, compensate for the disadvantages of the corresponding other technology. Furthermore, this provides redundant signal transmission. Overall, this improves the reliability of the radar system. Therefore, a more fault-tolerant radar system is achieved, which is particularly advantageous for autonomous driving. Alternatively, the line for transmitting electrical signals is preferably used as a communication interface between the central unit and one or more 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 one described above. The advantages achieved using the radar system can be similarly achieved using this method. The feature combinations of the disclosed radar system can be similarly applied to this method. Therefore, repeated descriptions of features and advantages are omitted.

[0027] According to a method step, an electric radar ramp signal is generated through a central unit (especially the aforementioned central unit).

[0028] In another step of the method, an optical radar carrier signal and an optical radar drive signal are provided via a central unit. The optical radar drive signal is based on the generated electronic radar ramp signal.

[0029] In addition, the optical radar carrier signal and the optical radar drive signal are coupled into the waveguide through the central unit.

[0030] In another step of the method, an optical radar drive signal coupled to the waveguide is received by a radar transmitting unit, and then converted into an electric radar drive signal by the radar transmitting unit.

[0031] In one step of the method, the radar transmitter of the radar transmitting unit is driven using an electric radar driving signal.

[0032] In addition, the radar receiver of the radar receiving unit receives radar echo signals, especially radar echo signals emitted by the radar transmitter based on the electric radar drive signal.

[0033] In another method step, an optical radar response signal is provided by a radar receiving unit and coupled into a waveguide by the radar receiving unit, the optical radar response signal including an optical radar echo signal generated based on a received radar echo signal.

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

[0035] In addition, radar information derived from radar response signals is output through the central unit.

[0036] In addition, the optical radar echo signal is converted to another frequency range by an optical mixer in the central unit and / or radar receiving unit.

[0037] Another aspect of the invention relates to a radar receiving unit for use in the aforementioned radar system. The radar receiving unit is preferably the aforementioned radar receiving unit. The radar receiving unit includes a radar receiver and an optical modulation unit configured to provide an optical radar response signal and couple it into a waveguide, the optical radar response signal including an optical radar echo signal generated based on a radar echo signal received by the radar receiver. The radar receiving unit also includes an optical mixer configured to convert the optical radar echo signal to another frequency range. The advantages achieved using this radar system can be achieved in a similar manner using the radar receiving unit. The characteristic combinations of the radar system disclosed regarding the radar receiving unit can be similarly applied to this radar receiving unit. Therefore, repeated descriptions of features and advantages are omitted.

[0038] Another aspect of the invention relates to a central unit for use in the aforementioned radar system. This central unit is preferably the aforementioned central unit. The central unit includes: a central optical receiving unit configured to receive an optical radar response signal coupled to a waveguide; an optical mixer configured to convert the received optical radar response signal to another frequency range; and an evaluation unit configured to evaluate the received optical radar response signal and output radar information derived therefrom. The advantages achieved using this radar system can be achieved in a similar manner using the central unit. The feature combinations of the radar system disclosed with respect to the central unit can be similarly applied to this central unit. Therefore, repeated descriptions of features and advantages are omitted.

[0039] In a preferred embodiment of the present invention, the central unit further includes a signal generator for generating an electric radar ramp signal and an optical transmission unit configured to provide an optical radar carrier signal and an optical radar drive signal based on the electric radar ramp signal generated by the signal generator and couple them into at least one waveguide.

[0040] Another aspect of the invention relates to a method for operating a radar receiving unit. The advantages achieved using the radar receiving unit can be achieved in a similar manner using this method. The combinations of features disclosed regarding the radar receiving unit can be similarly applied to this method. Therefore, repeated descriptions of features and advantages are omitted.

[0041] According to this method, a radar receiving unit receives radar echo signals and provides an optical radar response signal, which is then converted to another frequency range. The optical radar response signal includes an optical radar echo signal generated based on the received radar echo signals. Furthermore, the optical radar response signal (converted to a different frequency range) is coupled into a waveguide.

[0042] Another aspect of the invention relates to a method for operating a central unit. The advantages achieved using the central unit can be achieved in a similar manner using this method. The feature combinations disclosed regarding the central unit can be similarly applied to this method. Therefore, repeated descriptions of features and advantages are omitted.

[0043] In this method, an optical radar response signal coupled to a waveguide is received by a central unit, converted to another frequency range, and evaluated. Finally, radar information derived from the optical radar response signal is output by the central unit.

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

[0045] The various method steps of the method according to the invention are also preferably configured as one or more processes, which run on one or more processors in one or more electronic computing devices and are generated during the implementation of one or more computer programs. The computing devices are preferably configured to cooperate with other components to achieve the functionality described herein. Similarly, the various components of the radar system, especially the central unit, are preferably configured as central (one-piece) or distributed (multi-piece) components.

[0046] The various components of the radar system, particularly the evaluation unit of the central unit, are preferably at least partially configured as one or more processes, which run on one or more processors in one or more electronic computing devices and are generated during the implementation of one or more computer programs. The computing devices are preferably configured to cooperate with other components to achieve the functionality described herein. The instructions for the computer programs are also preferably stored in memory, such as RAM elements. However, the computer programs may also be stored in non-volatile storage media, such as CD-ROMs, flash memory, etc.

[0047] Those skilled in the art will also understand that the functionality of multiple computers (data processing devices) can be combined or combined in a single device, or the functionality of a particular data processing device can be distributed across multiple devices in order to implement the steps of the method according to the invention without departing from the method according to the invention.

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

[0049] The central unit and / or radar receiving unit preferably also includes additional electrical and / or optical components. Examples include transimpedance amplifiers and other amplification devices used in amplifying electrical signals, and / or electrical modulators that may be used in signal processing.

[0050] This invention is particularly applicable to environmental acquisition in motor vehicles. Exemplary applications include driver assistance systems (e.g., parking assistance systems, adaptive cruise control, etc.) and automated and / or autonomous driving. However, in principle, this invention can also be used in all fields where radar systems are used, such as aircraft radar systems, ship radar systems, shipping container terminals, warehouse robotic logistics, rail vehicles, military technology, etc.

[0051] The various embodiments of the invention mentioned in this application can be advantageously combined with each other, unless otherwise stated in individual cases. Attached Figure Description

[0052] The invention will now be explained in the embodiments with reference to the accompanying drawings. Wherein: Figure 1 A schematic diagram of a radar system according to one embodiment is shown. Figure 2 A schematic diagram of a radar receiving unit according to a first embodiment is shown. Figure 3 A schematic diagram of a radar receiving unit according to a second embodiment is shown. Figure 4 A schematic diagram of a radar receiving unit according to a third embodiment is shown. Figure 5 A schematic diagram of a method for operating a radar system according to an execution form is shown, and Figure 6a -c shows a schematic diagram of a motor vehicle with a distributed radar system according to one embodiment. Detailed Implementation

[0053] Detailed embodiments, exemplarily presented in the accompanying drawings, will now be described. The effects and features of these embodiments are described with reference to the drawings. In the drawings, the same reference numerals denote the same elements, and redundant descriptions are omitted. This disclosure may be implemented in various forms and should not be construed as being limited to the embodiments presented herein. Rather, these embodiments are examples so that this disclosure is thorough and complete, and fully conveys to those skilled in the art the aspects and features of this disclosure.

[0054] Therefore, methods, elements, and techniques that are not essential for a full understanding of the aspects and features of this disclosure may not be described. In the accompanying drawings, the relative dimensions of elements, layers, and regions may be exaggerated for illustrative purposes.

[0055] As used herein, the term “and / or” includes all combinations of one or more of the listed elements. Furthermore, the use of “may” in describing embodiments of this disclosure means “one or more embodiments of this disclosure.” In the following description of embodiments, singular terms may also include plural terms unless explicitly stated in the context.

[0056] Although the terms "first" and "second" are used to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Thus, for example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The expression "at least one," when it appears before a list of elements, modifies the entire list, not just a single element of the list.

[0057] Terms such as “basically” and “approximately” are used as approximate terms rather than descriptions of degree, and inherent biases in measurements or calculations should be taken into account as recognized by those skilled in the art. When the term “basically” is used in conjunction with a feature that can be expressed numerically, the term “basically” means a range of at least + / - 5% of the value centered on that value.

[0058] Figure 1 A schematic diagram of a radar system 100 according to one embodiment is shown. For clarity, optical connections and photonic components are generally represented by dashed lines. The radar system 100 includes at least one radar transmitting unit 50, at least one radar receiving unit 70, a central unit 10, and at least one waveguide 12 coupling the central unit 10 to the radar transmitting unit 50 and the radar receiving unit 70. In a preferred design, the radar system 100 includes a plurality of radar transmitting units 50, 50', a plurality of radar receiving units 70, 70', and a plurality of waveguides 12, 12', as shown in... Figure 1 As shown in the diagram. In this case, there is a distributed radar system 100, in which all radar transmitting units 50, 50' are preferably centrally driven by a drive signal provided by a central unit 10. Since the signal transmission is carried out optically via waveguides 12, 12', the signal transmission is phase-locked, that is, no drive signal that undesirably changes phase reaches the radar transmitting units 50, 50' and the radar receiving units 70, 70'.

[0059] The central unit 10 includes a signal generator 18 for generating an electric radar ramp signal and an optical transmission unit 20a. The optical transmission unit is configured to provide an optical radar carrier signal and an optical radar drive signal based on the electric radar ramp signal generated by the signal generator 18. Preferably, the optical radar carrier signal ( Figure 1(the intermediate optical path in the middle) and the optical radar drive signal ( Figure 1 The optical radar carrier signal (the upper optical path in the image) is coupled as a (separate) single signal to one or more waveguides 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 also configured to couple the optical radar carrier signal and the optical radar drive signal to at least one waveguide 12, 12' so as to transmit them via at least one waveguide 12, 12' to radar transmitting units 50, 50' and / or radar receiving units 70, 70'. It is understood that for (pure) radar transmitting units 50, 50', it is sufficient that their - with Figure 1 The difference is that only the optical radar drive signal is received. Reception of the optical radar carrier signal through radar transmitting units 50, 50' is preferably not mandatory.

[0060] The central unit 10 also includes an evaluation unit 14 and preferably at least one control interface 16 connected to the evaluation unit 14 and configured to operate a 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 an electric radar ramp signal and provide this electric radar ramp signal to the optical transmitting unit 20a. Although Figure 1 Two control interfaces 16 are presented, but the number of control interfaces 16 shown is arbitrary, and this disclosure is not limited thereto. Instead, it is preferable to use only one or more control interfaces 16. The control interfaces 16 are primarily used for manipulating and / or exchanging signals with various electronic and photonic components, and thus for electronic connection with them. Communication between the central unit 10 and the radar receiving unit 70 for purposes such as parameterization and diagnostics is preferably conducted optically and / or electrically.

[0061] The optical transmitting unit 20a preferably includes a light source (e.g., a laser diode 22) and / or a modulator (especially an optical modulator 20). Using an optical modulator 20 has the advantage that the laser diode 22 itself does not need to be modulated, but only needs to provide an optical radar carrier signal during CW operation. This allows the use of a cost-effective laser diode 22. To control the laser diode 22, it is electrically connected to the control interface 16. The optical modulator 20 is preferably configured to change the material properties of the waveguide 12 to modulate the optical wave. Preferably, the refractive index and / or absorption characteristics of the waveguide 12 are changed. The optical modulator 20 is preferably configured to change the material properties of the waveguide 12 by means of charge carriers (current), by means of an electric field (voltage), by means of temperature (heating electrodes), and / or by means of mechanical deformation.

[0062] In order to transmit the optical radar carrier signal ( Figure 1 (the intermediate optical path in the middle) and the optical radar drive signal ( Figure 1 The upper optical path in the optical transmission unit 20a generates a (independent) single signal. The optical transmission unit 20a also preferably includes an optical splitter 26 or an optical switch 26, configured to guide the optical radar carrier signal generated by the laser diode 22 during CW operation to the optical modulator 20 via a first optical path and / or via a second optical path. Figure 1 The intermediate optical path in the middle is guided to waveguides 12, 12'. Alternatively, the central unit 10 includes two laser diodes 22, each of which is directed into one of the two optical paths. In this case, the optical splitter 26 or optical switch 26 is not required.

[0063] The optical transmitting unit 20a also preferably includes an optical control unit 24 (preferably located in the first and / or second optical path), and / or additional optical splitters 28 or optical switches 28 located in the first and / or second optical paths. The optical control unit 24 is electrically connected to the control interface 16 and is connected in the optical path between the optical modulator 20 and the (first) optical output (not shown) of the optical transmitting unit 20a, or between the optical splitter 26 or optical switch 26 and the (second) optical output (not shown) of the optical transmitting unit 20a. The optical control unit 24 is configured to control the amplitude, phase, and / or polarization of the respective transmitted optical signals and to check for (undesired) differences or deviations. In other words, the optical control unit 24 ensures that the output optical signals are as desired, i.e., correct. The additional optical splitters 28 or optical switches 28 are primarily used for controlling the output of the respective optical signals, especially in the case of multiple radar transmitting units 50, 50' and / or multiple radar receiving units 70, 70', for controlling the correct distribution of the respective optical signals. Preferably, an additional optical splitter 28 or optical switch 28 is connected in the corresponding optical path between the optical control unit 24 and the optical output terminal (not shown) of the optical transmitting unit 20a.

[0064] The central unit 10 also includes a central optical receiving unit 30 for receiving optical radar response signals coupled to the waveguide 12. The central optical receiving unit 30 is configured to convert the optical radar response signals into electromagnetic radar response signals. The optical receiving unit 30 preferably includes at least one photodiode. The evaluation unit 14 is configured to evaluate the received optical radar response signals and output radar information (not shown) derived therefrom. For this purpose, the evaluation unit 14 is electrically connected to the central optical receiving unit 30. The evaluation unit 14 is preferably configured to perform frequency analysis via Fourier transform to determine the (time-based) range coordinates and / or Doppler frequencies (relative velocities) of one or more targets. The radar information derived from the optical radar response signals is preferably output to a driver assistance system and / or an autonomous driving system.

[0065] The central unit 10 preferably further includes an amplifier 32, a signal processing unit 34, an ADC converter 36 (ADC-to-digital converter), and / or a preprocessing unit 38. The amplifier 32 is preferably connected between the optical receiving unit 30 and the evaluation unit 14. The signal processing unit 34 is preferably connected between the optical receiving unit 30 (especially after the amplifier 32) and the evaluation unit 14. The ADC converter 36 is preferably connected between the optical receiving unit 30 (especially after the signal processing unit 34) and the evaluation unit 14. The preprocessing unit 38 is preferably connected between the optical receiving unit 30 (especially after the ADC converter 36) and the evaluation unit 14. The amplifier 32 is preferably configured to amplify the electronic radar response signal. Examples of the amplifier 32 are a transimpedance amplifier (TIA) and a voltage-controlled amplifier (VGA). The signal processing unit 34 is preferably configured to process the amplitude and / or phase of the electronic radar response signal and / or filter the electronic radar response signal. The preprocessing unit 38 is preferably configured to perform a Fast Fourier Transform (FFT).

[0066] The radar transmitting unit 50 includes an optical receiving unit (not shown) and a radar transmitter (not shown). The optical receiving unit of the radar transmitting unit 50 is configured to receive an optical radar drive signal coupled to the waveguide 12 (via the optical transmitting unit 20a of the central unit 10) and convert it into an electrical radar drive signal. This is preferably done using a photodiode. The optical receiving unit is also configured to provide the (converted) electrical radar drive signal to the radar transmitter (to drive the radar transmitter). For this purpose, the optical receiving unit is electrically connected to the radar transmitter. In other words, the radar transmitter can be manipulated using the electrical radar drive signal to emit a frequency signal carrying a radar ramp signal (generated in the central unit 10). The frequency signal emitted by the radar transmitter is preferably in the frequency range of 24.05 GHz to 26.65 GHz (according to the radio certification standards for automotive radar ETSI EN 302 858 and ETSI EN 302 288) and / or in the frequency range of 76 GHz to 81 GHz (according to the radio certification standards for automotive radar ETSI EN 301 091 and ETSI EN 302 264).

[0067] According to the present invention, the generation of radar drive signals is performed optically and centrally in the central unit 10. Signal transmission between the central unit 10 and the radar transmitting unit 50, and between the central unit 10 and the radar receiving unit 70, is also performed optically. This can be achieved by co-integrating optical and electrical components for generating and receiving radar echo signals. Compared to electrical transmission, less signal attenuation occurs in the optical transmission of radar drive signals, enabling the common supply of radar drive signals to a large number of radar transmitting units 50, 50' and radar receiving units 70, 70'. Furthermore, compared to electrical circuits, the phase-locked loop of the radar drive signals is achieved through optical signal transmission, which makes it particularly easy to implement a distributed radar system 100 having multiple radar transmitting units 50, 50' and radar receiving units 70, 70'.

[0068] Furthermore, waveguide 12 has a significantly smaller weight than the corresponding electrical circuitry and is less sensitive to external interference (such as electromagnetic fields). By centrally generating the radar drive signal optically in the central unit 10, radar transmitting units 50, 50' and radar receiving units 70, 70' can be manufactured and provided in a compact structure with a smaller size. This saves structural space and cost. Moreover, the complexity of a single radar transmitting unit 50, 50' or a single radar receiving unit 70, 70' is reduced, allowing it to be manufactured simply and economically, and to be easily and quickly replaced in case of failure.

[0069] According to the present invention, the central unit 10 and / or the radar receiving unit 70 includes an optical mixer configured to convert the optical radar echo signal to another frequency range. In other words, the optical mixer can be implemented in various ways in the radar system 100, i.e., on the radar receiving unit 70 and / or the central unit 10. In one implementation, the optical radar echo signal is up-mixed or down-mixed in the optical domain on the radar receiving unit 70, i.e., the frequency of the optical radar echo signal is increased or decreased. In the mentioned case, the radar response signal coupled to the waveguide 12 has already been converted to another frequency range (see [link to relevant documentation]). Figure 4 In an alternative implementation, optical mixing is performed via an optical mixer on the central unit 10 (see [link]). Figure 2 and Figure 3 In this case, the optical radar response signal coupled to waveguide 12 is received at its constant frequency by the central optical receiving unit 30 of the central unit 10, where the frequency of the optical radar response signal (or the optical radar echo signal contained therein) is up-mixed 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 to another frequency range by optical mixers at the radar receiving unit 70 and at the central unit 10, respectively. Preferably, the optical radar echo signal is down-mixed, i.e., the signal frequency is reduced. In the radar system 100, down-mixing is used to convert the most common high-frequency radar signal information (typically in the gigahertz range) to a lower frequency sub-gigahertz range (IF). In other words, after optical detection, the radar echo signal is photoelectrically converted and down-mixed to a lower frequency IF range. Traditional radar systems implement this down-mixing in the electrical domain using electronic mixers, while optical mixing of radar echo signals offers various advantages, such as reduced power consumption and space requirements, as it eliminates the need for dedicated electronic mixers. Furthermore, compared to purely electronic solutions, the optical implementation of mixing provides increased flexibility relative to variable RF carrier frequencies and occupied RF bandwidth.

[0070] The optical mixer of the central unit 10 and / or radar receiving unit 70 preferably includes one or more photodiodes. Photodiodes are well-suited for use as optical mixers because frequency conversion can be easily achieved when converting optical signals to electrical signals, as the optical radar drive signal is incident on the photodiode as an auxiliary frequency in the sense of a local oscillator (LO) to generate an intermediate frequency (IF). In this regard, it is preferable to use the optical radar drive signal as an auxiliary frequency to convert the radar echo signal to an intermediate frequency. The photodiode of the optical receiving unit 30 can preferably be used directly as an optical mixer.

[0071] refer to Figures 2 to 4 Now, let's explain in more detail. Figure 1 The radar receiving unit 70 is presented in three different implementations. Figure 2 A schematic diagram of a radar receiving unit 70 according to a first embodiment is shown. Figure 3 A schematic diagram of a radar receiving unit 70 according to a second embodiment is shown. Figure 4 A schematic diagram of a radar receiving unit 70 according to a third embodiment is shown.

[0072] The first two embodiments of the radar receiver unit 70 are unable to convert, for example, downmix the received radar echo signal (optically) to another frequency range. In these embodiments, the central unit 10 includes an optical mixer configured to convert the received radar echo signal to another frequency range. Conversely, the radar receiver unit 70 according to the third embodiment includes its own optical mixer configured to convert the received radar echo signal to another frequency range. In this respect, the optical mixer on the central unit 10 is not mandatory (but is possible) in this embodiment.

[0073] like Figure 2As shown, the radar receiving unit 70 according to the first embodiment includes a radar receiver 72 and an optical modulation unit 80. The optical modulation unit is configured to provide an optical radar response signal and couple it into a waveguide 12. The optical radar response signal includes a radar echo signal received via the radar receiver 72 and an optical radar carrier signal coupled to the central unit 10 via the waveguide 12. In other words, the radar receiver 72 receives the radar echo signal against a frequency signal emitted by the radar transmitter according to a radar ramp signal and provides it 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 to generate an optical radar response signal, which is transmitted to the central unit 10 via the waveguide 12. Preferably, the received (electric) radar echo signal is amplified by a low-noise amplifier 74 and an additional amplifier 76 (in terms of amplitude) of the radar receiving unit 70 and supplied to the signal processing unit 78 of the radar receiving unit 70. The signal processing unit 78 is preferably configured to process the amplitude and / or phase and / or filter the electronic radar echo signal, and then provide it to the optical modulation unit 80. The radar receiving unit 70 preferably also includes optical control units 82 in both the optical input and optical output paths. The optical control units 82 are configured to control the amplitude, phase, and / or polarization of the corresponding optical signals and check for (undesired) differences or deviations. In other words, the optical control units 82 ensure that the optical signals are as desired, i.e., correct. To manipulate the electronic and photonic components, the radar receiving unit 70 includes two control interfaces 84. Although... Figure 2 Two control interfaces 84 are presented, but the number of control interfaces 84 shown is arbitrary, and this disclosure is not limited thereto. Instead, it is preferable to use only one or more control interfaces 84. The control interfaces 84 are primarily used for manipulating and / or exchanging signals with the various electronic and photonic components, and thus for electronic connection with them. In a preferred design, the control interfaces 84 are also configured for exchanging electronic and / or photonic signals with the central unit 10.

[0074] Since the radar response signal coupled to the waveguide 12 via the radar receiving unit 70 according to the first embodiment includes the received radar echo signal and the optical radar carrier signal, but excludes the optical radar drive signal, for this embodiment of the radar receiving unit 70, the optical transmitting unit 20a of the central unit 10 preferably includes another optical splitter 29 or optical switch 29 in the first optical path (see...). Figure 1 It is configured to guide the optical radar drive signal to the optical output end (not shown) and / or the central optical receiving unit 30 via the first optical path.

[0075] refer to Figure 3 The radar receiving unit 70 according to the second embodiment is explained in more detail. Details already provided are omitted. Figure 2 The description of the features described in the radar receiving unit 70 according to the first embodiment is as follows. The differences will be explained in more detail below.

[0076] According to the second embodiment, the radar receiving unit 70 also includes a combiner 86 and a second optical input path. Figure 3 The intermediate optical input path is used to receive the radar drive signal coupled to the waveguide 12 by the central unit 10 and guide it to the combiner 86. Preferably, an optical control unit 82 is provided in the second optical input path. The combiner 86 is arranged in the optical output path between the optical modulation unit 80 and the output of the optical output path, particularly before 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 drive signal and couple it into the waveguide 12.

[0077] Since the radar response signal coupled to the waveguide 12 via the radar receiving unit 70 according to the second embodiment includes the received radar echo signal, the optical radar carrier signal, and the optical radar drive signal, there is no need for the optical splitter 29 or optical switch 29 in the first optical path of the central unit 10 to convert the radar response signal to another frequency range via the optical mixer on the central unit 10.

[0078] refer to Figure 4 The radar receiving unit 70 according to the third embodiment is explained in more detail. Details already provided are omitted. Figure 3 The description of the features described in the radar receiving unit 70 according to the second embodiment is as follows. The differences will be explained in more detail below.

[0079] According to the third embodiment, the radar receiving unit 70 further includes an optical splitter 88 and / or an optical switch 88, an optical receiving unit 90, and an additional optical modulation unit 92. The additional 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 (via combiner 86) to the optical receiving unit 90. The optical splitter 88 and / or optical switch 88 of the radar receiving unit 70 is preferably configured to guide an optical radar carrier signal, or a portion thereof, transmitted via waveguide 12 to the optical receiving unit 90 and / or optical modulation unit 80 of the radar receiving unit 70. The optical radar carrier signal is preferably guided from the optical splitter 88 and / or optical switch 88 to the additional optical modulation unit 92.

[0080] The optical receiving unit 90 preferably includes a photodiode serving as an optical mixer. This optical mixer is preferably further configured to provide the radar echo signal, optically converted (to another frequency range), to the optical modulation unit 80. The converted radar echo signal is then provided to the optical modulation unit 80 as an electrical signal. The optical radar drive signal received by the radar receiving unit 70 is preferably directed to the optical mixer. In this case, the optical radar drive signal serves as an auxiliary frequency required to convert the optical radar echo signal to the intermediate frequency range (IF range) via the optical mixer. In other words, in this design, the radar receiving unit 70 is configured to perform optical mixing of the radar echo signal. Therefore, the radar response signal coupled to the waveguide 12 already includes the radar echo signal converted to the intermediate frequency range (IF range). Therefore, mixing of the radar echo signal on the central unit 10 is unnecessary, thereby reducing the complexity of the central unit 10.

[0081] Figure 5 A schematic diagram of a method for operating (especially the above-described) radar system 100 according to an execution form is shown.

[0082] In the first method step 102, an electric radar ramp signal is generated by the central unit 10.

[0083] According to step 104 of the second method, the central unit 10 provides an optical radar carrier signal and an optical radar drive signal based on the generated electric radar ramp signal.

[0084] In addition, the optical radar drive signal and the optical radar drive signal are coupled into the waveguide 12 through the central unit 10 (third method step 106).

[0085] In the fourth method step 108, the optical radar drive signal coupled to the waveguide 12 is received by the radar transmitting unit 50 and converted into an electric radar drive signal by the radar transmitting unit.

[0086] According to step 110 of the fifth method, the radar transmitter of the radar transmitting unit 50 is driven by the electric radar driving signal.

[0087] In addition, the radar receiver 72 of the radar receiver unit 70 is used to receive the radar echo signal (sixth method step 112).

[0088] In the seventh method step 114, an optical radar response signal is provided by the radar receiving unit 70 and coupled to the waveguide 12 by the radar receiving unit. The optical radar response signal includes an optical radar echo signal generated based on the received radar echo signal.

[0089] According to step 116 of the eighth method, the optical radar response signal coupled to the waveguide 12 is received by the central unit 10 and evaluated by the central unit.

[0090] In addition, radar information derived from the radar response signal is output through the central unit 10 (ninth method step 118).

[0091] In addition, the optical radar echo signal is converted to another frequency range by the optical mixer of the central unit 10 and / or the radar receiving unit 70.

[0092] Figure 6a -c shows various schematic diagrams of a motor vehicle with a distributed radar system 100 according to one embodiment. Figure 6a The motor vehicle is shown in a front view. Figure 6b The rear view shows the motor vehicle, and Figure 6c The motor vehicle is shown in a side view.

[0093] The distributed radar system 100 includes multiple radar transmitting units 50, 50' and multiple radar receiving units 70, 70', which are distributed along different sides of the vehicle. In other words, Figure 6a -c illustrates possible integration of the (photon) radar system 100 into a motor vehicle. For example, the windshield, rear windshield, and / or bumper can be integrated into the front and / or rear sides of the motor vehicle, and the vehicle floor, roof, and / or B-pillar can be integrated into the sides of the vehicle.

[0094] In particular, the following advantages are observed: co-integration of the EPIC (Electronic-Photonic Integrated Circuit) process in SiGe, SiN, CMOS, and hybrid BiCMOS processes, resulting in cost savings, reduced structural space, and greater flexibility compared to electronic solutions with increased variable RF carrier frequency and RF bandwidth. Furthermore, it enables simple hardware-based transmission signal generation with low noise and low phase noise; a larger, clearly defined range for distance measurement and thus avoidance of over-range; clear re-identification of the transmitted signal in the receiver through encoding; the possibility of simultaneous transmission of multiple measurement signals from multiple transmitting antennas and clear recovery in the receiver; less computational cost in signal processing; energy savings for signal processing; and / or use in photonic radar systems within electronic-photonic, photonic, and electronic semiconductor circuits. The methods described herein can be adapted for LiDAR systems, camera systems, and satellite communication systems in both civilian and military applications.

[0095] List of reference numerals 10 Central Unit 12,12' waveguide 14 Evaluation Units 16 Control Interface 18 Signal Generator 20a Optical Transmission Unit 20 Optical modulators 22 Laser Diodes 24 Optical Control Unit 26 Optical splitter / optical switch 28 Optical splitter / optical switch 29 Optical splitter / optical switch 30 Central optical receiving unit 32 Amplifier 34 Signal Processing Unit 36 ADC converter 38 Preprocessing Units 50 radar transmission units 50' Additional radar transmitting unit 70 Radar Receiving Unit 70' Additional radar receiving unit 72 Radar Receiver 74 Low-noise amplifier 76 Amplifier 78 Signal Processing Unit 80 Optical Modulation Unit 82 Optical Control Unit 84 Control Interface 86 combiner 88 Optical splitter / optical switch 90 Optical Receiving Unit 92. Additional optical modulation units 100 Radar System 102 First Method Step - Generating Radar Ramp Signal 104 Second Method Step - Providing Optical Radar Drive Signal 106 Third Method Step - Coupled Optical Radar Drive Signal 108 Fourth Method Step - Receiving and Converting Radar Drive Signals 110 Fifth Method Step - Driving the Radar Transmitter 112 Sixth Method Step - Receiving Radar Echo Signals 114 Seventh Method Step - Providing and Coupling Radar Response Signal 116 Eighth Method Step - Receiving and Evaluating 118 Ninth Method Step - Output Radar Information.

Claims

1. A radar system (100), comprising: - At least one radar transmitting unit (50) having an optical receiving unit and a radar transmitter, - At least one radar receiving unit (70), which has a radar receiver (72) and an optical modulation unit (80), and - A central unit (10), which is coupled to the radar transmitting unit (50) and the radar receiving unit (70) via at least one waveguide (12), in, The central unit (10) includes a signal generator (18) for generating an electric radar ramp signal and an optical transmission unit (20a). The optical transmission unit is configured to provide an optical radar carrier signal and an optical radar drive signal based on the electric radar ramp signal generated by the signal generator (18) and couple them into the at least one waveguide (12). The optical receiving unit of the radar transmitting unit (50) is configured to receive the optical radar driving signal coupled to the waveguide (12), convert it into an electric radar driving signal, and provide the electric radar driving signal to the radar transmitter. The optical modulation unit (80) of the radar receiving unit (70) is configured to provide an optical radar response signal and couple it into the waveguide (12). The optical radar response signal includes an optical radar echo signal generated based on the radar echo signal received via the radar receiver (72). The central unit (10) further includes a central optical receiving unit (30) for receiving optical radar response signals coupled to the waveguide (12) and an evaluation unit (14). The evaluation unit is configured to evaluate the received optical radar response signals and output radar information derived therefrom. The central unit (10) and / or the radar receiving unit (70) include an optical mixer configured to convert the optical radar echo signal to another frequency range.

2. The radar system (100) according to claim 1, wherein, The optical mixer includes one or more optoelectronic components.

3. The radar system (100) according to claim 2, wherein, The plurality of optoelectronic components include a first pair of balanced photodiodes.

4. The radar system (100) according to claim 3, wherein, The plurality of optoelectronic components include a second pair of balanced photodiodes designed as receivers coherent with the first pair of balanced photodiodes, wherein the optical mixer includes an optical splitter configured to split the optical radar echo signal into at least two mutually phase-shifted portions and to direct a portion of the optical radar echo signal to each of the pairs of balanced photodiodes.

5. The radar system (100) according to any one of the preceding claims, wherein, The central unit (10) further includes 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 drive signal or a portion thereof to the central unit (10) as an optical mixer.

6. The radar system (100) according to any one of the preceding claims, wherein, The radar receiving unit (70) further includes an optical splitter (88) and / or an optical switch (88) and an additional optical modulation unit (92), the additional optical modulation unit being 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. The optical splitter (88) and / or optical switch (88) of the radar receiving unit (70) are configured to guide the optical radar carrier signal or a portion thereof transmitted via the waveguide (12) to the optical mixer and / or the optical modulation unit (80) of the radar receiving unit (70), and The optical mixer is further configured to provide the optically converted radar echo signal to the optical modulation unit (80) in an electrical manner.

7. The radar system (100) according to any one of the preceding claims further includes: - At least one additional radar transmitting unit (50'), and - At least one additional radar receiving unit (70') is coupled to the central unit (10) via at least one and / or additional waveguides (12').

8. A method for operating a radar system (100), comprising the following steps: - The (102) electric radar ramp signal is generated through the central unit (10). - The central unit (10) provides (104) an optical radar carrier signal and an optical radar drive signal based on the generated electromagnetic radar ramp signal. - The optical radar carrier signal and the optical radar drive signal are coupled (106) to the waveguide (12) through the central unit (10). - The radar transmitting unit (50) receives the optical radar drive signal coupled to the waveguide (12) and converts it (108) into an electric radar drive signal. - The radar transmitter of the radar transmitting unit (50) is driven (110) using the aforementioned electric radar drive signal. - The radar receiver (72) of the radar receiving unit (70) receives the radar echo signal (112). - An optical radar response signal is provided by the radar receiving unit (70) and coupled (114) to the waveguide (12), the optical radar response signal including an optical radar echo signal generated based on the received radar echo signal. - The optical radar response signal coupled to the waveguide (12) is received and evaluated (116) by the central unit (10), and - Radar information derived from the radar response signal is output (118) by the central unit (10). The optical radar echo signal is converted to another frequency range by the optical mixer of the central unit (10) and / or the radar receiving unit (70).

9. A radar receiving unit (70) for use in a radar system (100) according to any one of claims 1 to 7, comprising: - Radar receiver (72), - An optical modulation unit (80) configured to provide an optical radar response signal and couple it into the waveguide (12), the optical radar response signal comprising an optical radar echo signal generated based on a radar echo signal received via the radar receiver (72), and - An optical mixer configured to convert the optical radar echo signal to another frequency range.

10. A 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) is provided for receiving the optical radar response signal coupled into the waveguide (12). - An optical mixer configured to convert the received optical radar response signal to another frequency range, and - Evaluation unit (14), which is configured to evaluate the optical radar response signal switched to another frequency range and output radar information derived therefrom.

11. The central unit (10) according to claim 10, further comprising: - A signal generator (18) is set up to generate the electromagnetic radar ramp signal, and - An optical transmitting unit (20a) is configured to provide an optical radar carrier signal and an optical radar drive signal based on an electric radar ramp signal generated by the signal generator (18) and couple them into the at least one waveguide (12).

12. A method for operating a radar receiving unit (70) according to claim 9, comprising the following steps: - Receive (112) radar echo signals using the radar receiving unit (70), and - Provide an optical radar response signal and convert (114) it to another frequency range and couple it into a waveguide (12), the optical radar response signal including an optical radar echo signal generated based on the received radar echo signal.

13. A method for operating a central unit (10) according to claim 10 or 11, comprising the following steps: - Receive (116) the optical radar response signal coupled into the waveguide (12) and convert it to another frequency range, and evaluate it. - Output (118) radar information derived from the optical radar response signal.

14. The method of claim 13, further comprising the step of: - Generates (102) electromagnetic radar ramp signal, - Based on the generated electromagnetic radar ramp signal, provide (104) optical radar carrier signal and optical radar drive signal, and - Couple (106) the optical radar carrier signal and the optical radar drive signal to at least one waveguide (12).

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