Method for determining target information of a target object based on an alternating transmission of up-chirp signals and down-chirp signals, as well as sensor system and vehicle

Abstract

The invention relates to a method for determining target information of a sensor system (2) which has transmitting elements (3) and receiving elements (4), wherein - in a transmission process (44), each transmission element transmits a first chirp signal (36) having a temporally increasing frequency and a second chirp signal (37) having a temporally decreasing frequency, - reception signals (39) based on the transmitted first or second chirp signals (36, 37) are received by the reception elements (4), - a first received signal sequence (40) is formed from such received signals which are based on the first chirp signals (36), - a second received signal sequence (41) is formed from such received signals which are based on the second chirp signals (37), - a first frequency spectrum is generated on the basis of the first received signal sequence (40) and a second frequency spectrum is generated on the basis of the second received signal sequence (41), and - the target information is determined depending on the first and second frequency spectrum. Furthermore, the invention relates to a sensor system (2) and a vehicle (1).

Description

[0001] The invention relates to a method for determining at least one item of target information of a target object of a sensor system, wherein the sensor system has a plurality of transmitting elements and a plurality of receiving elements.

[0002] Furthermore, the invention relates to a sensor system and a vehicle with a corresponding sensor system.

[0003] For example, JP 5247069 B2 discloses an exemplary radar device. Here, a received signal can be subjected to pulse compression, and a distance to a target can be calculated from a signal generated by the pulse compression. The relative distance to the target, the relative speed to the target, and a relative acceleration are calculated from a difference in the distance to the target based on the intensity of a signal generated by the different recompression.

[0004] Furthermore, US 2018 / 0 203 105 A1 discloses a method for determining distances and relative speeds of objects using radar. The determination can be made using ramp-like frequency-modulated transmission signals.

[0005] An object of the present invention is to increase the resolution of a sensor system, in particular for environmental detection, and at the same time to simplify the corresponding signal processing.

[0006] This problem is solved by a method, a sensor system, and a vehicle according to the independent patent claims. Useful further developments arise from the dependent patent claims.

[0007] One aspect of the invention relates to a method for determining at least one item of target information of a target object of a sensor system, wherein the sensor system has a plurality of transmitting elements and a plurality of receiving elements, wherein - in particular, in a transmission process, each transmission element of the plurality of transmission elements transmits a first chirp signal, which has a temporally increasing frequency, and a second chirp signal, which has a temporally decreasing frequency, into an environment of the sensor system, - in particular, with at least some of the receiving elements, reception signals based on the transmitted first and second chirp signals of the plurality of transmitting elements are received, - in particular, a first received signal sequence is formed from such received signals of the received received signals (which are based on the first chirp signals of the plurality of transmitting elements, - in particular, a second received signal sequence is formed from such received signals of the received received signals which are based on the second chirp signals of the plurality of transmitting elements, - in particular, a first frequency spectrum is generated on the basis of the first received signal sequence and a second frequency spectrum is generated on the basis of the second received signal sequence, and - in particular depending on the first and second frequency spectrum, the at least one target information is determined.

[0008] The proposed method can be used to improve a sensor system for environmental detection, in particular by increasing the triggering capability of the sensor system. At the same time, the proposed method offers a further advantage in that signal processing with regard to target detection and / or environmental detection can be carried out more simply, i.e., with minimal computational effort. By transmitting a respective first chirp signal and a respective second chirp signal by each transmitting element, one or more signal processing steps, which are carried out after receiving received signals, can be carried out more simply and, in particular, less complexly. By transmitting the two chirp signals, a transmit signal can be designed, which has a positive effect on the triggering capability of the sensor system while simultaneously simplifying signal processing.Today's sensor systems, which feature high resolution and distance, suffer from the problem that a significant amount of signal processing is required for target association. This can be remedied with the help of the proposed method.

[0009] High-resolution radar sensors, such as sensor systems, are indispensable today, for example, for automated driving. High resolution is required in all measurable dimensions, such as distance, speed, azimuth angle, and elevation angle. The proposed method can be used to achieve this, as it not only provides high resolution but also simplifies data and signal processing, reducing computational effort. Above all, the proposed method can be used to create a modulation method without range migration for distributed, high-resolution radar sensors.

[0010] The proposed method avoids or reduces the effects of range migration and the associated association problems. This reduces the risk of false associations, i.e., incorrect target detection. Furthermore, computational complexity can be minimized. Furthermore, the proposed method offers the advantage of avoiding or eliminating migration effects due to large equipment requirements. Furthermore, the requirements regarding frequency modulation of the oscillator can be reduced because, for example, frequency jumps are no longer present in the transmitted signal. Likewise, the present invention can reduce the computational effort in signal processing. This also allows energy savings for signal processing to be achieved.

[0011] In particular, the present method can be applied or used for sensor systems such as radar systems, lidar systems, camera systems, and satellite communication systems. For example, radar sensors today are often operated based on the principle of rapid chirp modulation. In this case, either up chirps or only down chirps are used. The present invention is also advantageous here, since the proposed method allows for the use of an advantageous combination of the two modulation methods.

[0012] The proposed method enables easier target detection of one or more target objects, such as a radar target, within a sensor system. This allows, above all, environmental detection with the sensor system to be improved and made more effective.

[0013] A transmission process is a transmission cycle, such as a MIMO cycle. During this transmission process, all transmission elements or at least a plurality of transmission elements can emit or transmit signals. During the transmission process, each or a plurality of transmission elements can emit a first chirp signal and a second chirp signal. In other words, each transmission element transmits both a first chirp signal and a second chirp signal per transmission process. The first chirp signal can be an up-chirp signal and the second chirp signal a down-chirp signal. Furthermore, the first chirp signal can be a positive chirp signal and the second chirp signal can be a negative chirp signal. For example, the first chirp signal has a rising frequency ramp and the second chirp signal a falling frequency ramp.The chirp signals emitted during the transmission process can, for example, be reflected or re-radiated by one or more target objects in the environment, so that corresponding received signals can be received by the receiving elements. Some of these received signals can be based on the first chirp signals, while others can be based on the second chirp signals.

[0014] For example, the first received signal sequence and the second received signal sequence can be generated or modified with the help of an electronic evaluation unit of the sensor system. The first and second received signal sequences are a combination or a bundling of received signals that are based either on the first chirp signals or on the second chirp signals.

[0015] The received signals assigned or allocated to the first and second received signal sequences can then be used to generate the first and second frequency spectra by converting them into the spectral range or into a spectrum. These frequency spectra can be used on the system side, for example, with the evaluation unit of the sensor system, to determine or ascertain at least one piece of target information or several pieces of target information regarding target objects, such as radar targets.

[0016] In one embodiment, it is provided that in the transmission process, a first chirp signal is alternately transmitted by a transmission element of the plurality of transmission elements and a second chirp signal is transmitted by a transmission element of the plurality of transmission elements.

[0017] This allows a first chirp signal to be transmitted alternately, followed by a second chirp signal, or first a second chirp signal followed by a first chirp signal. In other words, signals can be transmitted alternately with an increasing frequency ramp or with a decreasing frequency ramp during the transmission process. The transmission process continues, in particular, until all or selected transmission elements have transmitted both their first chirp signal and their second chirp signal. Thus, for example, a first transmission element can transmit a first chirp signal. Subsequently, a second transmission element can transmit a second chirp signal. Subsequently, the first transmission element can in turn transmit the second chirp signal, and subsequently the second transmission element can transmit the first chirp signal.Thus, the transmission process can be described by the following transmission type: first chirp signal - second chirp signal; first chirp signal; second chirp signal.

[0018] In other words, signal processing can be simplified by alternately transmitting rapidly modulated frequency ramps in the sequence - "Up Chirp", "Down Chirp", "Up Chirp", "Down Chirp", ...

[0019] Thus, the present invention does not use up-chirp modulation or down-chirp modulation to transmit signals by means of ramp modulations, as is the case with current radar sensors, but rather alternates the transmission of up-chirp signals and down-chirp signals, which in turn can be taken into account in the subsequent evaluation.

[0020] In one embodiment, it is provided that, during the transmission process, a first chirp signal is first alternately transmitted by each transmitting element of the plurality of transmitting elements, and then, during the transmission process, a respective second chirp signal is alternately transmitted by each transmitting element of the plurality of transmitting elements. In other words, a respective second chirp signal can first be transmitted by all transmitting elements or the selected transmitting elements of each transmitting element of the plurality of transmitting elements. In other words, the first chirp signals of all transmitting elements or all selected transmitting elements are transmitted first. Thus, the transmission or up-chirp signals are transmitted first.For example, as soon as all or all selected transmitting elements have transmitted their first chirp signal, all transmitting elements or all selected transmitting elements can immediately transmit their second chirp signal within the transmission process. Thus, after all up-chirp signals from all transmitting elements have been transmitted, all down-chirp signals from the transmitting elements are then transmitted.

[0021] In one embodiment, it is further provided that, depending on a predetermined transmission sequence of each transmission element of the plurality of transmission elements, a first or second chirp signal is transmitted during the transmission process. For example, a corresponding numbering or position number can be assigned or associated with each transmission element of the respective transmission elements. The transmission sequence, i.e., a transmission sequence, can be used to determine the order in which the individual transmission elements transmit or emit a signal. For example, it can be determined at which position in the sequence each transmission element transmits.Thus, for example, a transmission time can be determined for each transmitting element so that the respective transmitting elements can be instructed or controlled accordingly to transmit their first chirp signal or their second chirp signal as required.

[0022] In one embodiment, it is further provided that in a first half of the transmission process, a first or second chirp signal is transmitted by each transmission element of the plurality of transmission elements depending on the predetermined transmission sequence, and in a second half of the transmission process, a first or second chirp signal is transmitted by each transmission element of the plurality of transmission elements in a transmission sequence that is inverse to the predetermined transmission sequence. To explain this pictorially, for example, in the first half of the transmission process, i.e., in the first time range of the transmission process, transmission elements 1 to 4 can transmit their signals. Immediately following the first half of the transmission process, transmission elements 4 to 1 can transmit their signals in the second half of the transmission process, i.e., in the second time window of the transmission process.In other words, the transmitting element that last transmitted a signal in the first half of the transmission process transmits a signal first in the second half. In other words, the order of the transmitting elements that transmitted first in the first half of the transmission process can transmit a signal in reverse, or mirrored, order in the second half of the transmission process.

[0023] For example, the respective first chirp signals can be transmitted in the first half of the transmission process, and the respective second chirp signals can be transmitted in the second half of the transmission process.

[0024] In one embodiment, the first frequency spectrum is generated by means of a Fourier transformation of the first received signal sequence, and the second frequency spectrum is generated by means of a Fourier transformation of the second received signal sequence. In other words, the received signals assigned to the respective sequences can be transformed into the Fourier spectrum, resulting in the two different frequency spectra. Thus, a spectrum can be formed or generated for both up-chirp signals and down-chirp signals.

[0025] A frequency spectrum, also called a spectrum, can be used to specify the various frequencies of signals. A frequency spectrum can be calculated from the underlying signals by applying the Fourier transform.

[0026] The Fourier transform, more precisely the continuous Fourier transform, is a mathematical method from the field of Fourier analysis with which aperiodic signals can be decomposed into a continuous spectrum.

[0027] In one embodiment, the first and second frequency spectra each have a distance-dependent and a speed-dependent component. Since the frequency spectra are based on the received signals, which in turn can contain radar information or target information, they have, for example, a distance-dependent phase term, such as the distance-dependent component, and a Doppler-dependent phase term, such as the speed-dependent component, for determining target information. These components can be used later to determine the desired information regarding the target object.

[0028] In one embodiment, the first frequency spectrum is multiplied by the second frequency spectrum, whereby the speed-dependent components compensate for each other, with a result of the multiplied frequency spectra being taken into account when determining the target information. In other words, a product of the two individual spectra can be formed using a mathematical operation, such as multiplication. Due to the two different chirp signals, the speed-dependent component of the two frequency spectra can differ in sign. Thus, this speed-dependent component can be canceled out or eliminated when the two spectra are multiplied.The resulting result thus represents information or a signal that is dependent solely on the Doppler frequency, i.e., the speed-dependent component. This means that the target information, which can be determined based on this result, can be determined more easily and with less computational effort. This significantly simplifies the signal processing that can subsequently be performed, for example, with regard to environment detection.

[0029] In one embodiment, it is provided that distance information, angle information, and / or speed information relating to the target object is provided along with the target information. Thus, a distance to the target object, a speed of the target object, an azimuth angle, and / or an elevation angle relative to the target object can be determined in a simple manner, in particular with significantly lower computational requirements, and can be made available, in particular, for environmental detection or target detection. This is particularly advantageous for the use of the sensor system in the automotive sector, since the target information can be made available, for example, to a driver assistance system or another autonomous vehicle system.

[0030] In one embodiment, at least one further transmission process is carried out immediately after the transmission process, wherein in the further transmission process, each transmission element of the plurality of transmission elements transmits a first chirp signal and a second chirp signal into the environment of the sensor system, wherein received signals relating to the further transmission process are taken into account when forming the first and second received signal sequences. In other words, several transmission processes carried out immediately one after the other in time can be used to carry out the most accurate and error-minimized target detection or environmental detection possible. The received signals respectively emitted back or reflected back to the receiving elements can be assigned to or selected from the two received signal segments, depending on which chirp signal they are based on.

[0031] For reliable environmental detection, for example, continuous, immediate transmission processes can be carried out one after the other in order to be able to better detect moving objects, for example.

[0032] In one embodiment, the transmission of the first and second chirp signals is carried out based on a multiple-input / multiple-output method. Thus, the transmission process can be referred to as a MIMO cycle. In other words, each transmitting antenna can emit both an up chirp and a down chirp within a MIMO cycle.

[0033] A further aspect of the invention relates to a sensor system for environmental detection, which comprises a plurality of transmitting elements, a plurality of receiving elements, and at least one electronic evaluation unit. The sensor system is designed to carry out a method according to the preceding aspects or an advantageous development thereof. In particular, a method of the aforementioned aspect can be carried out or implemented with the aid of the sensor system just described.

[0034] In particular, a transmitting device and a receiving device can be integrated on a single semiconductor chip, for example, in a CMOS, SiM-CMOS, Bi-CMOS, hybrid Bi-CMOS, or with processes on photonic-electronic co-integrated chips. Thus, for example, with the aid of the invention, a radar sensor device or the sensor system can be mass-produced using standardized semiconductor processes.

[0035] In particular, the sensor system can be used to perform frequency conversion of a terahertz carrier signal into the gigahertz frequency range after optical signal transmission and, conversely, reception of gigahertz signals with modulation on terahertz carrier signal.

[0036] In particular, the proposed sensor system can be used in motor vehicles. In particular, the sensor system can be used, for example, in at least partially autonomously operated motor vehicles, especially in fully autonomously operated motor vehicles. Such automated driving requires reliable environmental perception, which can be achieved by the sensor system. The environment can be detected using sensors such as radar, lidar, and cameras. These could be examples of the application area of the radar sensor device. The sensor system can perform a holistic 360-degree three-dimensional detection of the environment, so that all static and dynamic objects can be detected.

[0037] The sensor system can be used as an alternative to Lidar, since Lidar in particular plays a key role in redundant, robust environment detection, as this type of sensor can measure distances and angles more precisely in environment detection and can also be used for classification.

[0038] In particular, the sensor system can be used in at least partially autonomous vehicles, but especially in fully autonomous vehicles. However, to enable such automated driving, reliable environmental perception is essential. The environment is recorded using sensors such as radar, lidar, or cameras. A holistic 360-degree three-dimensional recording of the environment is particularly important so that all static and dynamic objects can be detected. The sensor system can be used for this purpose. In particular, lidar plays a key role in redundant, robust environment detection, as this type of sensor can measure distances more precisely in environment detection and can also be used for classification. However, these lidar sensors are cost-intensive and their construction complex.360-degree three-dimensional environment detection is particularly problematic, as it requires either many smaller individual sensors, which typically operate with many individual light sources and detector elements, or large lidar sensors. Furthermore, lidar sensors are susceptible to weather influences such as rain, fog, or direct sunlight. This sensor system can remedy this.

[0039] Radar sensors and radar sensor devices are also established in automotive engineering and provide reliable and fail-safe data in all weather conditions. Even poor visibility conditions, such as rain, fog, snow, dust, or darkness, barely affect their detection reliability. However, according to the state of the art, their resolution is currently limited; in particular, series-produced radars in use are only designed with an angular resolution of approximately 2 degrees. To meet the requirements for increased automation in automotive engineering with safe driving functions, radar sensor devices are designed to provide three-dimensional images with a high angular resolution in the range of 0.1 degrees and below, with high immunity to disturbances from their surroundings.This cannot be achieved with conventional radar technology according to the state of the art, as the resolution of such systems is too low. The sensor system according to the invention advantageously intervenes precisely in this area.

[0040] The sensor system can be designed as a photonic radar sensor device, which achieves an increase in resolution by cointegrating electronic and photonic components into a single semiconductor chip. The tracking of an FMCW signal as well as all signal processing and evaluation are performed at the central station. Each transmit and receive module has an electronic-photonic cointegrated chip, a so-called EPIC chip. Silicon photonics technology is used for the cointegration. This enables the monolithic integration of photonic components, radio-frequency electronics, and digital electronics on a single chip. The technical innovation of such a system lies in the signal transmission of gigahertz signals using the optical carrier signal in the terahertz frequency range.A central station, which can also be referred to as a central electronic processing unit, generates an optical carrier frequency in terahertz. The transmitted signal is modulated at one-eighth the radar frequency and sent via the optical fiber to the antenna chips. Frequency multiplication occurs there, allowing the radar radiation to be emitted by the antenna chips. Signal detection occurs in the opposite direction. All data is processed at the central station.

[0041] However, such a design is very complex in the implementation of gigahertz electronics at the chip level. In particular, the on-chip frequency multiplication following detection by a photodiode is technically challenging and poses a significant challenge with regard to gigahertz signal generation with a high signal-to-noise ratio and the lowest possible jitter. The gigahertz signal must be extensively stabilized in subsequent steps. Furthermore, gigahertz electronics are cost-intensive. Furthermore, high performance requirements are placed on the optical carrier, especially the laser, since a high level of optical power is required to generate a high-precision gigahertz signal, making single-phase loops difficult to implement for a radar array with many distributed radar semiconductor chips.In particular, two photonic-electronic semiconductor chips are still required for each transmit and receive channel, which leads to additional costs. The above-mentioned problems are at least partially, and in particular completely, solved by the sensor system according to the invention.

[0042] In particular, the invention utilizes an optical interface to couple the radiation of the laser device, which can also be configured as a CW laser, into a photonic semiconductor. This can be the optical transmission signal or a carrier signal of the CW laser.

[0043] The generation of the FMCW signal, as well as all signal processing and evaluation, are carried out by a central station, for example, the computer. Each transmit and receive module consists of an electronic-photonic cointegrated chip (so-called "EPIC chip"), and silicon photonics technology is used for cointegration. This enables the monolithic integration of photonic components, radio-frequency electronics, and digital electronics on a single chip ("electronic-photonic cointegration"). The technical innovation of such a system lies in the signal transmission of GHz signals using an optical carrier signal in the THz frequency range. A central station generates an optical carrier frequency (THz). The signal to be transmitted is modulated onto this frequency at 1 / 8 of the radar frequency and sent to the antenna chips via optical fiber.The frequency is multiplied eightfold on these, allowing the radar radiation to be emitted by the antenna chips. Signal detection occurs in the opposite direction. All data is processed at the central station.

[0044] The principle of electronic-photonic cointegration in a single chip, with silicon-on-insulator regions for the photonic components and bulk silicon regions for the electronic circuits, is a globally unique technology. Especially at high data rates, it enables high signal quality with low parasitic interference. The connection of the RF circuits for the radar antennas, including the frequency multiplier, to the optical transceiver can be implemented without additional wire or flip-chip bonding. Furthermore, chips can be optically and electrically tested at the wafer level, enabling a high yield in the subsequent module design. This technology enables extremely compact form factors and thus has significant relevance for the application of optical technologies based on silicon photonics in the automotive industry.

[0045] The hurdle to the productive use of optical fibers lies in the lack of scalability of currently available technologies. This scalability to large volumes is made possible by the technology for highly integrated manufacturing of electronic photonic integrated circuits. The result is a significant reduction in assembly costs and a more efficient cost structure. The development of data center solutions has resulted in comprehensive libraries of electronic and photonic components for data transmission at high bandwidths, which will be utilized in this project.

[0046] In an embodiment of the further aspect, it is provided that the sensor system has a control device which is designed to control the individual transmission elements of the plurality of transmission elements such that the individual transmission elements alternately transmit the respective first chirp signal or second chirp signal.

[0047] A further aspect of the invention relates to a vehicle with a sensor system according to the preceding aspect or an advantageous further development.

[0048] For example, the vehicle may be manually operated, partially autonomous, or fully autonomous. In other words, the vehicle may be a highly automated vehicle.

[0049] In particular, the vehicle may be a motor vehicle, such as a passenger car or a truck.

[0050] In an embodiment of the further aspect, it is provided that the plurality of transmitting elements and / or the plurality of receiving elements are arranged distributed and spaced apart from one another on the vehicle. This allows for the most efficient detection of the vehicle's surroundings. The distributed arrangement of the individual antenna elements on the vehicle allows, in particular, 360-degree detection of the surroundings.

[0051] The transmitting and receiving elements can be configured as antenna elements. These can specifically form an antenna array comprising multiple antenna elements.

[0052] For example, the antenna elements of the antenna array can be configured in a sparse array configuration. In particular, the antenna elements of the antenna array can be arranged on the vehicle in a sparsely populated or weakly populated configuration.

[0053] Embodiments of individual aspects of the invention are to be considered advantageous embodiments of other aspects. In particular, the respective embodiments of individual aspects can be considered advantageous embodiments of all other aspects. This also applies in reverse.

[0054] Advantageous embodiments of the method(s) are to be regarded as advantageous embodiments of the sensor system and the vehicle. The sensor system and the vehicle have specific features that enable implementation of the method or an advantageous embodiment thereof.

[0055] For use cases or application situations that may arise during the method and which are not explicitly described here, it may be provided that, in accordance with the method, an error message and / or a request to enter user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0056] The invention also includes further developments of the sensor system according to the invention and the vehicle according to the invention that have features already described in connection with the further developments of the methods according to the invention. For this reason, the corresponding further developments of the sensor system according to the invention and the vehicle according to the invention are not described again here.

[0057] The invention also includes combinations of the features of the described embodiments.

[0058] Exemplary embodiments of the invention are described below. Shown are: Fig. 1 a schematic representation of a vehicle with a sensor system which has antenna elements of an antenna array arranged distributed on the vehicle; Fig. 2 a schematic representation of a block diagram of the sensor system from Fig. 1; Fig. 3 a schematic representation of another embodiment of the radar system from Fig. 1; Fig. 4 a sequence of different alternating transmitted up chirps and down chirps; Fig. 5 a schematic representation of the first chirp signals transmitted; Fig. 6 a schematic representation of the emitted second chirp signals; Fig. 7 an exemplary transmission scheme for transmitting different chirp signals by several transmitting elements; Fig.8 shows an exemplary chirp sequence, where here always a neighboring pair of the transmitted first and second chirp signals of a transmitting element T x4 and T x5 is shown; and Fig. 9 shows a further schematic section of the chirp sequence, where here, as a pair with respect to the two chirp sequences, a transmitting element T x3 and T x6 is considered.

[0059] The exemplary embodiments explained below are preferred exemplary embodiments of the invention. In the exemplary embodiments, the described components each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described exemplary embodiments can also be supplemented by further features of the invention already described.

[0060] In the figures, functionally identical elements are provided with the same reference numerals.

[0061] The Fig. Figure 1 shows various schematic views (front view, rear view, side view) of a vehicle 1, which may be a motor vehicle. The vehicle 1 includes, for example, a sensor system 2.

[0062] The sensor system 2 can, for example, be a radar system or an environmental sensor system of the vehicle 1. For this purpose, the sensor system 2 can be communicatively networked with one or more driver assistance systems or other vehicle systems. For example, the sensor system 2 can be a radar sensor or a lidar sensor or another type of sensor, particularly for vehicles. In addition to the use of the sensor system 2 in the vehicle 1, it can also be used in systems external to the vehicle.

[0063] For example, the sensor system 2 has at least one antenna array or multiple antenna arrays. The antenna array can in turn be formed from a plurality of antenna elements, such as transmitting elements 3 and / or receiving elements 4. The antenna elements can be arranged at a distance from one another on the vehicle 1, particularly for 360-degree surroundings detection.

[0064] The Fig. Figure 2 shows a conceivable embodiment of the sensor system 2. The sensor system 2 can comprise at least one radar sensor device 5 and a central electronic computing device 6. For example, the radar sensor device 5 and the central electronic computing device 6 can be separate and physically distinct units. The radar sensor device 5 can, for example, comprise the at least one antenna array. Otherwise, the antenna array can function as the radar sensor device 5.

[0065] The central electronic computing device 6 is a central processing unit. For example, the central electronic computing device 6 can generate an electrical control signal with which a laser device 7 can be actuated or controlled. The laser device 7 can be a CW laser, for example. With the help of the laser device 7, an optical transmission signal or a carrier signal 8 can be generated. The optical transmission signal 8 can in particular be referred to as an optical carrier signal in the terahertz frequency range. The central electronic computing device 6 can, for example, generate the optical carrier frequency. The signal to be transmitted is modulated onto this optical carrier frequency with one eighth of a radar frequency and transmitted, for example, to the radar sensor device 5. In this way, an eightfold frequency increase can take place.Again, with the aid of the radar sensor device 5, signals in the gigahertz frequency range can be received and transmitted to the central electronic computing device 6.

[0066] For example, the central electronic computing device 6 can be coupled to an optical input 10 and an optical output 11 of the radar sensor device 5 via at least one optical fiber 9. Thus, bidirectional signal transmission can occur between the central electronic computing device 6 and the radar sensor device 5.

[0067] For example, the central electronic computing device 6 can be referred to as an electronic evaluation unit.

[0068] The central electronic computing device 6 can further comprise an optical receiving unit 12, which is configured to receive an optical output signal 13 provided by the optical output 11 of the radar sensor device 5. Thus, the central electronic computing device 6 can be coupled to the radar sensor device 5 via an optical fiber or electronic interface, such as Ethernet. In particular, multiple radar sensor devices or antenna arrays can be coupled to the central electronic computing device 6. For example, the central electronic computing device 6 can comprise a processing unit 14 or a computing unit, with which the received optical output signal can be processed. Thus, signal acquisition and subsequent data processing of the received output signal 11 can be carried out.

[0069] In particular, the central electronic computing device 6 can have or provide all necessary control signals, data processing signals, modules and interfaces.

[0070] For example, the radar sensor device 5 can have, in addition to the optical input 10 and the optical output 11, at least one transmitting device 15 or transmitting antenna and at least one receiving device 16 or receiving antenna. Thus, the radar sensor device 5 has a receiving module and / or transmitting module. In particular, the transmitting device 15 and the receiving device 16 can be integrated on one and the same chip. It is also conceivable for them to be located on different semiconductor chips.

[0071] With the aid of the transmitting device 15, an electrical radar transmission signal 17, which is based on the optical transmission signal 8, can be transmitted into an environment 18 of the vehicle 1. Thus, a corresponding radar signal 17 can be transmitted depending on the optical transmission signal 8. If this signal 17 is reflected in the environment 18 by objects such as road users, roads, trees, or other objects, an electrical reception signal 19 corresponding to the electrical radar transmission signal 17 and reflected in the environment 18 can be received.

[0072] For example, the transmitting device 15 may have at least one antenna or one antenna unit or several antennas for transmitting.

[0073] For example, the transmitted radar transmission signal 17 or electrical transmission signal and the received reception signal 19 can be in the terahertz frequency range or gigahertz frequency range. Thus, with the aid of the sensor system 2, a frequency conversion of a terahertz carrier signal, in particular a transmission signal 8, into the gigahertz frequency range for transmission can be performed. Conversely, the reception of gigahertz signals can be performed with modulation onto the terahertz carrier signal. For example, the transmission device 15 can have at least one grating coupler and one photodiode for transmission. The reception device 16 can, for example, have two jitter couplers, a photodiode, and a modulator for reception.

[0074] Sensor system 2 can be modulated at 1 / 8 of the radar frequency and transmitted via optical fiber to the antenna chips or antenna elements, such as transmitting elements 3 and / or receiving elements 4. These undergo a frequency multiplication by eight, allowing the radar radiation to be emitted by the antenna chips. Signal detection can optionally be performed in the reverse direction. All data can be processed at the central station.

[0075] The Fig. 3 shows a further conceivable embodiment of the sensor system 2. Here, the sensor system also has the computing device 6, which in this embodiment can have a different configuration or equipment.

[0076] The sensor system 2 specifically comprises a plurality of transmitting-receiving units, such as the transmitting and receiving elements 3, 4, which can be arranged distributed on the vehicle 1, in particular for environmental detection.

[0077] The transceiver units or antenna elements can be used for both transmitting and receiving signals. Thus, the transceiver units are combined units for transmitting and receiving signals.

[0078] In particular, such a transmitting / receiving unit can be referred to as a transmitting and receiving module. This can be referred to or formed from an electronic-photonic co-integrated chip (so-called "EPIC chip"). The computing device 6, which can be referred to as the central processing unit, can also be formed from an electronic-photonic co-integrated chip. In particular, the computing device 6 is a physically and / or spatially separate unit from the transmitting / receiving units.

[0079] For example, the computing device 6 can have an optical unit or the laser device 7 or a laser. In particular, the optical unit can be designed as an optical source or as a CW laser. With the help of the optical unit, the optical transmission signal 8 or a carrier signal can be generated and thus provided. The optical transmission signal 8 can in particular be designed as an optical carrier signal in the terahertz frequency range. The computing device 6 can, for example, generate the optical carrier frequency. The signal to be transmitted can be modulated onto this optical carrier frequency with one-eighth of a radar frequency and transmitted, for example, to the transceiver units. In this way, frequency multiplication can take place. In turn, signals in the gigahertz frequency range can be received with the help of the transceiver units.

[0080] For example, the computing device 6 can be connected to a respective transmitting / receiving unit via a fiber optic cable 9, forming an optical transmission link. Signals, in particular optical signals, can be transmitted from the computing device 6 to the individual transmitting / receiving units via the fiber optic cable 9. In order to be able to send received signals from the transmitting / receiving units back to the computing device 6 for evaluation or signal processing, a respective transmitting / receiving unit can be optically coupled to the computing device 6 via an optical return channel 20.

[0081] The electrical transmission signal 17 can be transmitted, in particular into the surroundings 18, by at least one of the transmission / reception units. An electrical reception signal 19 corresponding to the electrical transmission signal 17 can also be received by the transmission / reception unit. For example, the transmission signal 17 can be reflected by an object in the surroundings 18 of the vehicle 1 and thus received as an electrical reception signal 19. The reception signal 19, which can be referred to as a radar signal, for example, can be transmitted or transferred to the computing device 6 for evaluation or signal processing. For this purpose, the electrical reception signal can be converted into an optical reception signal 21 by means of the transmission / reception unit. For example, this can be transmitted via the return channel 9 of the computing device. By means of an optical-electrical converter unit 22 orThe detector unit of the computing device 6 can convert the optical received signal 21 into an electrical signal 23. Unit 22 can be used, for example, for optical detection. For this purpose, the conversion can be performed, for example, via homodyne detection or heterodyne detection. Furthermore, unit 22 can perform a phase measurement and / or a phase length measurement.

[0082] Digitization can then again be performed via a digital interface 24. In particular, an analog-to-digital conversion can be performed here. For this purpose, the digital interface 24 can have an analog-to-digital converter. A processing unit 14 can be arranged downstream. This can be used, for example, for signal processing, particularly for a "low-level signal." For example, a Fast Fourier Transformation ("FFT") can be used for this purpose. The digitized, processed electrical signal 23 can then be made available to a CPU 25 of the computing device 6. In this case, radar information or environmental information contained in the electrical signal 23 can be evaluated or processed, respectively.Furthermore, an electrical return channel 26 can be provided, which provides feedback from at least one of the transmitting-receiving units to the computing device 6 and in particular to the digital interface 24.

[0083] In order to be able to carry out the most stable and low-noise environmental detection or detection of the sensor system 2, the optical transmission signal 8 can be adapted by means of frequency synthesis or gigahertz frequency synthesis. For this purpose, the computing device 6 can have a synthesis unit 27. For this purpose, the optical transmission signal 8 can be fed to or transmitted to the synthesis unit 27. For example, modulation can be carried out before the optical transmission signal 8 is made available to the synthesis unit 27. For this purpose, a modulator or modulation unit 28 can be provided. This can be designed, for example, as an arbitrary generator or arbitrary function generator (AWG). After the synthesis unit 27, for example, an optical control unit 29 and an optical switch orA distributor 30 may be provided in the computing device 6 in order to make appropriately processed signals from the synthesis unit 27 available to the transmitting / receiving units via the fiber optic cable 9. Furthermore, a control unit 31 may be controlled by the evaluation unit 25, in particular to monitor or control the generation of the optical transmission signal. Furthermore, a control unit or feedback loop 32 may be provided.

[0084] Furthermore, the computing device 6 is electrically connected to the transmitting / receiving units via an electrical transmission path 33. An electrical control signal 34 for controlling or driving the transmitting / receiving units or antenna elements can be transmitted via this electrical transmission path 33.

[0085] In particular, the computing device 6 serves to generate an optical carrier signal, the optical transmission signal 8, and feed it into a gigahertz frequency synthesis unit, e.g., the synthesis unit 27. The synthesized gigahertz signal can be transmitted in the optical spectral range via fiber, i.e., the fiber optic cable 9, to the transceiver units, so that, for example, a 77 gigahertz signal can be emitted or transmitted by the transceiver units. Signal detection, in turn, can be performed in the reverse direction. All data can be processed or processed in the computing device 6.

[0086] The configurations of the computing device 6 in Fig. 2 and Fig. 3 can be combined as desired.

[0087] To operate the sensor system 2 in such a way that it achieves high resolution and thus high detection capability while simultaneously requiring minimal signal processing and low computing power, the transmission of signals with the transmission elements 3 can be achieved by alternating signals. In this case, signals with an increasing frequency ramp and signals with a decreasing frequency ramp are transmitted alternately.

[0088] In the following, an exemplary embodiment will be explained how a modulation method without range migration can be created according to the invention for distributed high-resolution radar sensors, which may, for example, include sensor system 2. For this purpose, the method according to the invention can be advantageously used.

[0089] One component of the present invention may be that a “clever” arrangement of modulation areas of an exemplary transmission signal 35 (compare Fig.4). This transmission signal can be based on the composition of different transmitted partial signals of the different transmission elements 3. For this purpose, in one transmission process, i.e. in one MIMO cycle, a first chirp signal 36 can be generated by each transmission element 3, as shown in the Fig. 5 as an example, as well as a second chirp signal 37, which is shown in the Fig. 6 is shown as an example. In other words, each transmitting element 3 transmits an up chirp as well as a down chirp. As shown in the Fig. 5, the first chirp signals have 36 increasing frequency ramps. As shown in the Fig. 6, the second chirp signals have a falling or decreasing frequency ramp.

[0090] By appropriately controlling the transmitting elements 3, the first and second chirp signals 36, 37 can be transmitted in one transmission process in such a way that, for example, the transmission signal 35 results. As compared to the Fig. 5 and Fig. 6 indicates in the Fig. 4 the transmission signal 35 has correspondingly increasing and decreasing frequency ramps, which are formed from the chirp signals 36, 37.

[0091] In particular, the present invention can provide a modulation method which uses the Fig. 4 shown sequence with respect to the transmission signal 35.

[0092] In other words, a combination of alternating rapid-up chirps and rapid-down chirps can be achieved using the conceivable modulation method.

[0093] After all transmitting elements 3 have transmitted both their first chirp signal 36 and their second chirp signal 37 in the transmitting process, reception can be carried out using the receiving elements 4. The alternately transmitted first and second chirp signals 36, 37 can, for example, be directed in the environment 18 to a target object 38 (cf. Fig. 1), such as a radar target, then the corresponding reception signals 39 (compare Fig. 1) are received by at least some of the receiving elements 4 of a plurality of receiving elements. These received signals 39 can correspond either to the first chirp signals 36 or to the second chirp signals 37.

[0094] The received signals 39 can be selected or copied accordingly. In this case, received signals based on an up chirp can be assigned to a first received signal sequence 40 (see Fig. 4). Thus, up-chirp modulation can be performed here.

[0095] The reception signals 39, which are based on a down chirp, can be assigned to a second reception sequence 41 (see Fig. 4) are assigned or selected.

[0096] The received signals 39 of the first received signal sequence 40 can be described, for example, with the following formula: S(A)=(m,k,l)={S(u)⋅exp(jφR(dt(k,l))+jφD(vD,m))for odd0otherwise

[0097] In this formula, (φ R (dt(k,l))) represent a distance-dependent phase term, whereas (φ D (v D ,m)) represent a Doppler-dependent or velocity-dependent phase term.

[0098] The corresponding signal for the received signal 39 of the second received signal sequence 41 can be described with the following formula: S(B)=(m,k,l)={S(u)⋅exp(jφR(dt(k,l))+jφD(vD,m))for even 0 otherwise

[0099] As can be seen, the two previous formulas differ particularly in their signs. For example, the two received signals, the received signal sequences 40, 41, can each be separately transformed into the Fourier spectrum. In other words, a first frequency spectrum can be calculated or generated for the first received signal sequence 40 and a second frequency spectrum for the second received signal sequence 41. These two spectra can correspond to one another, so that these two spectra can be combined using a mathematical operation such as multiplication. In this case, a product of the two individual spectra, i.e. the first and second frequency spectrum, can be formed, for example in a processing step. From this, a relationship, in particular a formula, can be formed that is independent of the distance-dependent phase term, as can be seen in the following formula. S(tot)(m,k,l)=S(A)(m,k,l)⋅S(B)(m,k,l)

[0100] Using this formula, for example, a Doppler calculation can be performed with respect to the target object 38. Thus, target information regarding the target object 38 can be determined. By eliminating the distance-dependent phase term, the calculation can be performed more simply and with less computational effort, thus improving signal processing.

[0101] The transformation of the received signal sequences 40, 41 can be carried out, for example, by means of a Fourier transformation.

[0102] By determining the product of the two individual spectra, the distance-dependent part in S (ges)(m,k,l), for example, are omitted from the processing step. Only the dependence on the Doppler frequency remains, simplifying the calculation of possible target information. From this, a distance, a speed, an azimuth angle, and / or an elevation angle relating to the target object can be determined.

[0103] This signal processing minimizes problems of range migration. All subsequent signal processing steps, such as determining angles, can now be performed more simply and computationally efficiently.

[0104] For example, in a further variant or embodiment, an up-down chirp-modulated chirp sequence 42 can again be considered to compensate for the distance-dependent phase term and thus to eliminate the problem of range migration.

[0105] In the Fig.Figure 7 illustrates an exemplary transmission scheme. Here, the transmitted chirp signals 36, 37 are shown as examples in a correspondingly sorted representation, such as the formation of the received signal sequences 40, 41. Here, a respective pulse index and a respective transmission element are identified by description 43. The respective number denotes a pulse index, and the respective letter denotes the respective transmission element. Two transmission processes 44, 55 are shown as examples. These represent, for example, a respective MIMO cycle. In area 46, for example, various factors within the MIMO cycle are shown. In area 47, various factors outside of a MIMO cycle can be shown. The respective designations 48 represent a reference sequence, which must be compensated in order to compensate for the distance-dependent phase term.

[0106] For example, an apparatus such as an antenna array consisting of K-transmit antennas, such as the transmitting elements 3, can be used to implement the transmission scheme shown. Each transmitting element 3 can emit both an up chirp and a down chirp within a MIMO cycle. Furthermore, within a MIMO cycle, each transmitting element 3 can thus emit two chirps within a transmission process 44, 55. The sequence of transmissions in the transmitting elements 3, thus mapping the first half of the MIMO cycle, is continued in a mirrored order in the second half of the MIMO cycle. The mirroring can affect both the chirp gradient and the transmission sequence of the transmitting elements 3.

[0107] Relevant indices and constants are listed below which are relevant for the following explanations. ◯ MIMO: Number of up and down chirps within a MIMO cycle ◯ Frame: Number of MIMO cycles within a transmission cycle ◯ K: Number of transmitting antennas ◯ m: MIMO Cycle Index m=1…Frame ◯ L ref : Index as reference to the first K chirps ▪ l ref = 1 ... K ol: Index to K chirps within a MIMO cycle lref=1…K

[0108] To compensate for the distance-dependent phase term, the received chirps, i.e., the received signals 39 emitted by the transmitting elements, can be pairwise correlated with the received chirps from the subsequent MIMO cycles. This is explained in the table below. MIMO cycle Series index Index pair MIMO 1 1 1 Iref reference index 2 2 I Index to 3 3 4 4 4 5 (4,5) 3 6 (3,6) 2 7 (2,7) 1 8 (1,8) MIMO 2 1 9 2 10 3 11 4 12 4 13 (4,13) 3 14 (3,14) 2 15 (2,15) 1 16 (1,16) MIMO 3 1 17 2 18 3 19 4 20 4 21 (4,21) 3 22 (3,22) 2 23 (2,23) 1 24 (1,24) In particular, the previous table shows a representation of the chirps related to each other for compensation of distance-dependent phase terms. The "Index Pair" column shows the chirps related to each other for compensation.

[0109] In the following, a definition of the up-chirps and down-chirps, i.e. the two chirp signals 36, 37, can be explained in more detail.

[0110] For example, up-chirps and down-chirps can be described with the following definition. s(tl)≈{sup(t,l)≈exp(−j2π((fD+fτ)t+θτ+lθD))sdown(t,l)≈exp(−j2π((fD+fτ)t+θτ+lθD))

[0111] The variables are explained below. fD=f02cvr θD=f02cvrT fτ=BT2cR0 θτ=f02cR0 f D Speed-dependent frequency component f τ Distance-dependent frequency component i D Speed-dependent phase shift i τ Distance-dependent phase shift f0 carrier frequency c speed of light v r Radial velocity of hypothetical targets B Bandwidth of frequency modulation T Frequency modulation time duration R0 Radial target distance

[0112] In particular, the exemplary approach proposed for compensating the distance-dependent phase term θ τ by appropriate referencing of related chirps (l ref, l), i.e. between a first and second chirp signal 36, 37, a reception signal sequence, such as the reception signal sequences 40, 41, is generated, which represents a continuous rotation of the speed-dependent term θ D allows.

[0113] The following is an example explanation for the case of a down chirp.

[0114] If s(t, l ref ) = Down-Chirp and l ref ∈ 1 ...K then calculate the reference chirp in MIMO cycle m according to l = m * MIMO - l ref + 1 and set both chirps according to Δs(t)=sup(t,l)sdown(t,lref) in relation to each other.

[0115] In the Fig. An example is shown in Figure 8, where, as an example, for l ref = 4 and l = 5 the following follows: Δs(t)=sup(t,l=5)sdown(t,lref=1)=exp(−j2π((fD+fτ)t+θτ+5θD))exp(−j2π((fD+fτ)t+θτ+4θD))

[0116] This can produce the following result through a mathematical operation: Δs(t)=exp(−j2π(2fτt+θD))

[0117] Thus, Δs(t) has the phase position at the beginning of a new sequence of signals without distance-dependent phase terms.

[0118] For example, if s(t, l ref ) = Up-Chirp and l ref ∈ 1... K then calculate the reference chirp in MIMO cycle m according to l = m * MIMO - l ref + 1 and set both chirps according to Δs(t)=sdown(t,l)sup(t,lref) in relation to each other.

[0119] In the Fig. 9 shows an example, where for example for l ref = 3 and l = 6 the following follows: Δs(t)=sdown(t,l)sup(t,l)=exp(−j2π((fD+fτ)t+θτ+6θD))exp(−j2π((fD+fτ)t+θτ+3θD))

[0120] This can produce the following result through a mathematical operation: Δs(t)=exp(−j2π(−2fτt+3θD))

[0121] Thus, Δs(t) has the phase position at the beginning of a new sequence of signals without distance-dependent phase terms.

[0122] Thus, Δs(t) now has a phase position that is 3θ D was filmed further.

[0123] The scheme described above can optionally be continued for all subsequent chirps, so that the resulting signal sequence allows for a coherent Doppler calculation. The following table shows the resulting rotation factors u of the newly determined signal sequence for three consecutive MIMO cycles. MIMO cycle Order of emitting Index of emitted chirps Index pair (lref, l) MIMO 1 1 1 Iref reference index 2 2 I Pair formation index 3 3 4 4 Rotation factor for θ o 4 5 (4,5) 1 3 6 (3,6) 3 2 7 (2,7) 5 1 8 (1,8) 7 MIMO 2 1 9 2 10 3 11 4 12 4 13 (4,13) 9 3 14 (3,14) 11 2 15 (2,15) 13 1 16 (1,16) 15 MIMO 3 1 17 2 18 3 19 4 20 4 21 (4,21) 17 3 22 (3,22) 19 2 23 (2,23) 21 1 24 (1,24) 23

[0124] For example, the following resulting signal sequence can be considered: Δs(t,u)=exp(−j2π(−2fτt+uθD))

[0125] Here, it can be shown that the uniqueness of the maximum measurable radial velocity comes at the expense of reducing the computational effort required for a coherent calculation of the range Doppler spectrum. Furthermore, a factor of 2, which also results from the difference calculation, must be taken into account when calculating the target distance.

[0126] In particular, the explanations show how target information of the target object 38 can be better determined with the sensor system 2, since according to the invention the sensor system 2 can be designed with higher resolution. This is based in particular on the alternating transmission of up chirps and down chirps, so that a distance-dependent phase term and thus a distance dependence can initially be excluded or disregarded in the signal processing or mathematical calculation. This allows the signal processing to be improved. List of reference symbols 1 vehicle 2 Sensor system 3 transmitting elements 4 receiving elements 5 Radar sensor device 6 central electronic computing device 7 Laser device 8 optical transmission signal 9 Fiber optic 10 optical input 11 optical output 12 Receiving unit 13 Output signal 14 Processing unit 15 Transmitter 16 Reception device 17 electrical transmission signal 18 Surroundings 19 electrical reception signal 20 return channel 21 optical reception signal 22 optical-electrical converter unit 23 electrical signal 24 digital interface 25 CPU 26 electrical return channel 27 Synthesis unit 28 Modulator 29 optical control unit 30 optical distributors 31 Control unit 32 a feedback loop 33 electrical transmission line 34 electrical control signal 35 transmission signal 36 first chirp signal 37 second chirp signal 38 Target object 39 reception signals 40 first received signal sequence 41 second received signal sequence 42 Chirp sequence 43 Description 44, 45 transmissions 46, 47, 48 Description QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] JP 5247069 B2

[0003] US 2018 / 0 203 105 A1

[0004]

Claims

[1] Method for determining at least one item of target information of a target object (38) of a sensor system (2), wherein the sensor system (2) has a plurality of transmitting elements (3) and a plurality of receiving elements (4), characterized by , that - in a transmission process (44), each transmission element of the plurality of transmission elements (3) transmits a first chirp signal (36), which has a temporally increasing frequency, and a second chirp signal (37), which has a temporally decreasing frequency, into an environment (18) of the sensor system (2), - with at least some of the receiving elements (4) receive signals (39) based on the transmitted first and second chirp signals (36, 37) of the plurality of transmitting elements (3), - a first received signal sequence (40) is formed from such received signals of the received received signals (39) which are based on the first chirp signals (36) of the plurality of transmitting elements (3), - a second received signal sequence (41) is formed from such received signals of the received received signals (39) which are based on the second chirp signals (37) of the plurality of transmitting elements (3), - a first frequency spectrum is generated on the basis of the first received signal sequence (40) and a second frequency spectrum is generated on the basis of the second received signal sequence (41), and - depending on the first and second frequency spectrum, at least one target information is determined. [2] Method according to claim 1, characterized by that in the transmission process (44) a first chirp signal (36) is transmitted alternately by a transmission element of the plurality of transmission elements (3) and a second chirp signal (37) is transmitted alternately by a transmission element of the plurality of transmission elements (3). [3] Method according to claim 1, characterized byin that in the transmission process (44) a respective first chirp signal (36) is first transmitted alternately by each transmission element of the plurality of transmission elements (3) and then in the transmission process (44) a respective second chirp signal (37) is transmitted alternately by each transmission element of the plurality of transmission elements (3). [4] Method according to one of the preceding claims, characterized by that, depending on a predetermined transmission sequence, each transmission element of the plurality of transmission elements (3) transmits a first or second chirp signal (36, 37) in the transmission process (44). [5] Method according to claim 4, characterized byin that in a first half of the transmission process (45) a first or second chirp signal (36, 37) is transmitted by each transmission element of the plurality of transmission elements (3) depending on the predetermined transmission sequence, and in a second half of the transmission process (44) a first or second chirp signal (36, 37) is transmitted by each transmission element of the plurality of transmission elements (3) in a transmission sequence inverse to the predetermined transmission sequence. [6] Method according to one of the preceding claims, characterized by that the first frequency spectrum is generated by means of a Fourier transformation of the first received signal sequence (40) and the second frequency spectrum is generated by means of a Fourier transformation of the second received signal sequence (41). [7] Method according to one of the preceding claims, characterized by that the first and second frequency spectrum each have a distance-dependent and a speed-dependent component. [8] Method according to claim 7, characterized by that the first frequency spectrum is multiplied by the second frequency spectrum, whereby the speed-dependent components compensate each other, wherein a result of the multiplied frequency spectra is taken into account in determining the target information. [9] Method according to one of the preceding claims, characterized by that the target information provides distance information, angle information and / or speed information concerning the target object. [10] Method according to one of the preceding claims, characterized bythat immediately after the transmission process (44) at least one further transmission process (45) is carried out, wherein in the further transmission process (45) each transmission element of the plurality of transmission elements (3) transmits a first chirp signal (36) and a second chirp signal (37) into the environment (18) of the sensor system (2), wherein reception signals (39) relating to the further transmission process (45) are taken into account when forming the first and second reception signal sequences (40, 41). [11] Method according to one of the preceding claims, characterized by that in the transmission process (44, 45) the transmission of the first and second chirp signals (36, 37) is carried out on the basis of a multiple-input-multiple-output method. [12] Sensor system (2) for environmental detection, which has a plurality of transmitting elements (3), a plurality of receiving elements (4) and at least one electronic computing device (6), wherein the sensor system (2) is designed to carry out a method according to one of the preceding claims. [13] Sensor system (2) according to claim 12, comprising a control device (49) which is designed to control the individual transmitting elements of the plurality of transmitting elements (3) such that the individual transmitting elements alternately transmit the respective first chirp signal (36) or second chirp signal (37). [14] Vehicle (1) with a sensor system (2) according to 12 or 13. [15] Vehicle (1) according to claim 14, wherein the plurality of transmitting elements (3) and / or the plurality of receiving elements (4) are arranged spaced apart from one another on the vehicle (1).

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