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DE-102024210816-A1 - Photonic radar system with central digital downconversion

DE102024210816A1DE 102024210816 A1DE102024210816 A1DE 102024210816A1DE-102024210816-A1

Abstract

A radar system according to the invention comprises a central unit (Z), at least one radar transmitter (S-1, S-2, S-3, Sn) and at least one radar receiver (E-1, E-2, E-3, En), each comprising optical and electrical components. The central unit (Z) is configured to perform a down-conversion of a radar echo signal received by the at least one radar receiver (E-1, E-2, E-3, En).

Inventors

  • Pascal Marcel Seiler
  • Markus Robert
  • Andreas Noack
  • Thomas Gisder
  • Marc-Michael Meinecke
  • Heiko Gustav Kurz
  • Paniz Adibpour

Assignees

  • VOLKSWAGEN AKTIENGESELLSCHAFT

Dates

Publication Date
20260513
Application Date
20241111

Claims (11)

  1. Radar system comprising a central unit (Z), at least one radar transmitter (S-1, S-2, S-3, Sn) and at least one radar receiver (E-1, E-2, E-3, En), each comprising optical and electrical components, characterized in that the central unit (Z) is configured to perform a down-conversion of a radar echo signal received by the at least one radar receiver (E-1, E-2, E-3, En).
  2. radar system after Claim 1 , wherein the central unit (Z) is configured to send a first optical output signal to the at least one radar transmitting unit (S-1, S-2, S-3, Sn) and to send a second optical output signal to the at least one radar receiving unit (E-1, E-2, E-3, En) and to receive an optical input signal from the at least one radar receiving unit (E-1, E-2, E-3, En) which includes the radar echo signal.
  3. radar system after Claim 2 , wherein the first optical output signal is designed as a carrier signal modulated with a radar driver signal and the second optical output signal is designed as an unmodulated continuous wave signal.
  4. radar system after Claim 3 , wherein the optical input signal received in the central unit (Z) from the at least one radar receiving unit (E-1, E-2, E-3, En) comprises a radar echo signal modulated onto the unmodulated continuous wave signal, which is based on a radar signal originally emitted by the at least one radar transmitting unit (S-1, S-2, S-3, Sn).
  5. Radar system according to one of the preceding claims, wherein the radar transmitting units and the radar receiving units are each integrated into a common unit.
  6. Central unit (Z) for use in a radar system according to one of the Claims 1 until 5 , wherein the central unit (Z) for down-conversion of the received radar echo signal comprises a digital mixer (26) which converts the radar echo signal into a lower frequency signal by means of a local oscillator.
  7. Central processing unit (CPU) according to Claim 6 , wherein this comprises a first optical source (10) for generating the first optical output signal and a second optical source (11) for generating the second optical output signal.
  8. Central processing unit (CPU) according to Claim 6 , wherein this comprises a common optical source for generating the first optical output signal and the second optical output signal, and wherein a beam splitter is connected downstream of the optical source and one partial beam is used to generate the first optical output signal and a second partial beam is used to generate the second optical output signal.
  9. Radar receiving unit (E-1, E-2, E-3, En) for use in a radar system according to one of the Claims 1 until 5 , wherein the radar receiving unit (E-1, E-2, E-3, En) comprises an optical modulation unit (41) configured to modulate the radar echo signal onto the unmodulated continuous wave signal,
  10. Method for operating a radar system in which a central unit (Z), at least one radar transmitting unit (S-1, S-2, S-3, S-n) and/or at least one radar receiving unit (E-1, E-2, E-3, E-n) each comprise optical and electrical components, in which a digital down-conversion of a radar echo signal received from the at least one radar receiving unit (E-1, E-2, E-3, E-n) takes place in the central unit (Z).
  11. vehicle equipped with a radar system following one of the Claims 1 until 5 exhibits.

Description

The present invention relates to a radar system that can be operated, for example, in a vehicle. The present invention further relates to a central unit and a radar receiver unit of such a radar system. The invention also relates to a method for operating such a radar system. For driver assistance systems and safety systems in fully automated driving, the safest possible environmental perception is essential. This is achieved by capturing the environment using sensors such as radar, lidar, and camera sensors integrated into the vehicle. Based on the acquired sensor data, an environmental model can then be created using a suitable machine learning model. Perception modules can be used for this purpose, enabling the recognition of learned objects in the environment and forwarding this information to a planning module. The planning module can then take the recognized objects into account for trajectory planning and safe vehicle control. Particularly important here is a comprehensive 360° 3D capture, which allows for the complete 360-degree recording of all static and dynamic objects and the creation of the highest possible resolution 3D models of the environment. While lidar-based systems are capable of precise distance measurement and can also be used for classification, they are expensive and complex to build. Furthermore, lidar systems are susceptible to weather conditions such as rain, fog, or direct sunlight. Radar sensors, on the other hand, deliver reliable and fail-safe data in all weather conditions. Even poor visibility conditions like rain, fog, snow, dust, and darkness hardly affect their accuracy. However, their resolution is currently limited. For example, radar sensors currently used in series production in the automotive sector have a resolution of approximately 2°. This is insufficient to meet the requirements for Levels 4 and 5 of automated driving with safe driving functions, as these require radar sensors to provide three-dimensional images with a high resolution of 0.1° and below, with high insensitivity to interference from their surroundings. This cannot be achieved with conventional radar technology because the resolution of such systems is too low. Currently under development are so-called photonic radar systems, in which driver signals in the GHz range can be distributed to a multitude of radar sensors using an optical carrier signal in the THz frequency range. This allows for the co-integration of electronic and photonic components on a single semiconductor substrate, enabling extremely compact form factors for individual radar sensors and, consequently, arrays with numerous such radar sensors integrated into the vehicle. During the processing of the radar echo signals received by the radar sensors, the high-frequency radar signal information is downconverted in the individual sensor units. The radio frequency (RF) signal received from the antenna, typically in the gigahertz range, is converted into a lower intermediate frequency (IF) signal, typically in the sub-gigahertz range. In the DE 10 2017 221 257 A1 A radar system is disclosed in which signal transmission between a central unit and a radar transmitter or radar receiver is implemented optically. For this purpose, a radar driver signal is optically generated in the central unit and transmitted via at least one optical fiber to at least one radar receiver and/or at least one radar transmitter. In the radar transmitter, the radar driver signal is then converted into an electrical radar driver signal and used to drive a radar transmitter. A radar echo signal received by a radar receiver is mixed with the electrical radar driver signal in a mixer of the radar receiver. The mixed signal is then modulated onto the optical driver signal by means of a modulation unit, coupled into the optical fiber, and transmitted back to the central unit. In the central unit, the modulated optical signal is received and evaluated by means of an evaluation unit. The result is then provided as radar information. In contrast to this prior art, one object of the invention is to provide an improved radar system and an improved method for operating a radar system. This problem is solved by the independent claims. Preferred embodiments of the invention are the subject of the dependent claims. The invention is based on the realization that the electronics required in each individual sensor unit for downmixing the received radar echo signal into a lower frequency IF range can be avoided, thus eliminating the need for the Power consumption and the required chip area in the sensor units can be reduced if the mixing is performed digitally in a central unit, hereinafter also referred to as the backend. This allows for a significant simplification of the radar receiver units in the frontend. The radar system according to the invention therefore comprises a central unit, at least one radar transmitter unit and at least one radar receiver unit, each comprising opti