Device and method

Abstract

A device for light detection and ranging, wherein the device includes circuitry configured to: emit one or more optical beams to a scene; receive one or more reflected optical beams from the scene; switch between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein: in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; and in the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.

Description

[0001] Sony Semiconductor Solutions Corporation

[0002] DEVICE AND METHOD

[0003] TECHNICAL FIELD

[0004] The present disclosure generally pertains to a device and method for light detection and ranging.

[0005] TECHNICAL BACKGROUND A LiDAR (“Light Detection And Ranging”) system or device is typically designed for a specific use case, which especially include required distance resolution and maximally resolvable distance, e.g., an automotive long-range front LiDAR may want to cover up to hundreds of meters of distance at a distance resolution of tens of centimeters, while a short-range front LiDAR for a parking assistant use case may only want to cover several meters but at a centimeter distance resolution.

[0006] Furthermore, there exist several LiDAR use cases for a specific application, which have not to be covered at the same time. For example, for the mentioned automotive application the long-range front LiDAR use case will never operate at the same time as a short-range front LiDAR for parking assistance use case. In another application scenario, e.g. 3D (“three-dimensional”) scanning, a user may want to start with a coarser reconstruction by using a long-range mode and eventually refine the model details by switching to a more short-range, but more accurate, mode. However, to cover these different use cases, it would be needed to design and add individual LiDAR systems or devices for each use case, which is costly and makes the system more complex and more difficult to integrate.

[0007] Although there exist techniques for LiDAR devices, it is generally desirable to improve the existing techniques.

[0008] SUMMARY

[0009] According to a first aspect, the disclosure provides a device for light detection and ranging, comprising circuitry configured to:

[0010] emit one or more optical beams to a scene;

[0011] receive one or more reflected optical beams from the scene;

[0012] switch between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein:

[0013] in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; andSony Semiconductor Solutions Corporation

[0014] in the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.

[0015] According to a second aspect, the disclosure provides a method for light detection and ranging, comprising:

[0016] emitting one or more optical beams to a scene;

[0017] receiving one or more reflected optical beams from the scene;

[0018] switching between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein:

[0019] in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; and

[0020] in the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.

[0021] Further aspects are set forth in the dependent claims, the drawings and the following description.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Embodiments are explained by way of example with respect to the accompanying drawings, in which:

[0024] Fig. 1 schematically illustrates in a block diagram an embodiment of a device;

[0025] Fig. 2A schematically illustrates an embodiment of a frequency modulation in the CFMCW mode and the PRCM mode;

[0026] Fig. 2B schematically illustrates an embodiment of a frequency modulation in the CFMCW mode and the PRCM mode;

[0027] Fig. 3 schematically illustrates in a block diagram an embodiment of a transceiver frontend; and Fig. 4 schematically illustrates in a flow diagram an embodiment of a method.

[0028] DETAILED DESCRIPTION OF EMBODIMENTS

[0029] Before a detailed description of the embodiments under reference of Fig. 1 is given, general explanations are made.

[0030] As mentioned in the outset, there exist several LiDAR use cases for a specific application, which have not to be covered at the same time.Sony Semiconductor Solutions Corporation

[0031] However, to cover these different use cases, individual LiDAR systems or devices would need to be designed and added for each use case, which is costly and makes the system more complex and more difficult to integrate.

[0032] It has been recognized that there exist several application fields where a single LiDAR for different non-simultaneous use cases may be desirable in terms of cost, overall system or device complexity and integrability.

[0033] Furthermore, it has been recognized that many applications require a seamless transition between the use cases, requiring an automatic, scenario dependent and fast switching between the LiDAR device’s operation modes.

[0034] Coded Frequency Modulated Continuous Wave (CFMCW) modulation combines conventional FMCW with an additional Pseudo Random Code Modulation (PRCM) signal. Since in CFMCW FMCW and PRCM fulfill very different tasks, there exists a certain degree of freedom in designing the system parameters for either of the two combined technologies.

[0035] It has been recognized that it is possible to switch between CFMCW operation and pure PRCM operation, for example, by switching the laser operation mode between chirp operation (CFMCW mode) and constant carrier operation (PRCM mode), i.e., switching on and off the FMCW part of CFMCW. This gives the possibility to support at least two LiDAR modes for different (non-simultaneous) use cases.

[0036] It has further been recognized that it is possible to design a single set of system parameters for CFMCW and PRCM operation modes which can cover two uses cases. This allows for fast (or even seamless) switching between two operation modes at the cost of very little control logic and / or memory in some embodiments.

[0037] If more flexibility for the parameter design of the modes is required and / or more than two modes shall be supported, one may also design several system parameter sets. However, this may increase the system complexity (e.g., amount of control logic and memory) in some embodiments and may also reduce the transition speed between operation modes.

[0038] It has been recognized that a single LiDAR device can be designed, operated and switched in a multi-mode fashion to cover at least two non-simultaneous use cases for a specific application. Furthermore, a control loop has been recognized to switch between the modes (or at least two use cases), based on the obtained system outputs (distance and / or radial velocity and / or amplitude) and / or further external control inputs.Sony Semiconductor Solutions Corporation

[0039] Hence, some embodiments pertain to a device for light detection and ranging, wherein the device includes circuitry configured to:

[0040] emit one or more optical beams to a scene;

[0041] receive one or more reflected optical beams from the scene;

[0042] switch between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein:

[0043] in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; and

[0044] in the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.

[0045] The circuitry includes typical optical components such as optical circuits, in particular integrated optical circuits, and typical electronic components configured to achieve the functions as described herein.

[0046] The electronic components may include electronic drivers for driving a laser and one or more actuators, one or more ADCs, one or more DACs, actuators for moving optical parts, photodetectors (e.g., a balanced detector) and the like configured to achieve the functions as described herein. The electronic components may include electronic circuits - such as one or signal generation circuits, one or more processors (e.g., a digital signal processor (“DSP”)) and the like - configured to achieve the functions as described herein. The functionality of the electronic circuitry may be implemented by hardware and / or software.

[0047] The optical components may include one or more light sources such as a laser (e.g., semiconductor laser), lenses, mirrors, optical filters, irises, optical fibers, optical waveguides, a splitter, circulators, optical amplifiers, electro-optical modulators, phase modulators, optical mixers (e.g., a coupler or an optical hybrid), interferometers (e.g., Mach-Zehnder interferometer), a diffractive optical element, a metasurface and the like configured to achieve the functions as described herein.

[0048] An emitted optical beam has a wavelength in a wavelength range corresponding to the ultraviolet spectrum (e.g., UVA ranging from 315 to 380 nanometers) or the visible spectrum (380-780 nanometers) or the infrared spectrum (780 to 3000 nanometers).

[0049] In some embodiments, the circuitry is configured to process the one or more received reflected optical beams to obtain a distance estimation and a velocity estimation for each of the one or more received reflected optical beams.Sony Semiconductor Solutions Corporation

[0050] Generally, the processing of the one or more received reflected optical beams may include optical and electrical signal processing, which will be discussed in more detail under reference of Fig. 1 and Fig. 3 below.

[0051] The modulation of an emitted optical beam according to the individual code signal in each of the CFMCW mode and the PRCM mode may be in amplitude and / or phase and / or frequency.

[0052] In the CFMCW mode and the PRCM mode, the modulation according to the individual code signal may be introduced, for instance, by guiding the output of a laser or an optical waveguide through an electro-optical modulator which is driven according to the respective individual code signal.

[0053] Each individual code signal may include a Gold code or Kasami code or Zadoff-Chu code.

[0054] Each individual code signal may include a cyclic prefix.

[0055] The frequency chirp signal includes an up-ramp during which the frequency is increased and a down-ramp during which the frequency is decreased. The frequency chirp signal may be a triangular chirp signal.

[0056] Each individual code signal may include one or more code repetitions.

[0057] In the CFMCW mode, each individual code signal may include one or more code repetitions in a ramp. In the CFMCW mode, each individual code signal may include a different code for each up-ramp and down ramp.

[0058] In the CFMCW mode, the modulation of an emitted optical beam according to the frequency chirp signal may be introduced, for example, by using a laser that is driven with an electric chirp signal such that the laser emits a continuous wave which frequency changes in accordance with the electric chirp signal.

[0059] For the PRCM mode, the electric chirp signal is switched, for example, to an electric signal which keeps the output frequency of the laser constant.

[0060] Accordingly, a LiDAR device is provided which allows fast and seamless switching between the CFMCW mode and the PRCM mode to cover different non-simultaneous use cases with the suitable operation mode.

[0061] In some embodiments, the circuitry is configured to use a common set of main system parameters in the PRCM mode and in the CFMCW mode.

[0062] In some embodiments, the common set of main system parameters are the individual code signals, a measurement time, a sample rate and a data block size for Fast-Fourier Transform.Sony Semiconductor Solutions Corporation

[0063] There are further system parameters, which may be important to consider for different design cases, e.g., modulation bandwidth of the frequency chirp signal, for example, if the measurement time is fixed but the distance resolution shall be adjusted.

[0064] It has further been recognized that it is important to identify when to switch between the operation modes, i.e., to identify the different use cases.

[0065] Hence, in some embodiments, the circuitry is configured to switch between the CFMCW mode and the PRCM mode based on information obtained from processing the one or more reflected optical beams.

[0066] In some embodiments, the estimated distances and / or radial velocities and / or amplitude related measurements may be used to control the switching process.

[0067] For the amplitude related measurements, it can be made use of the correlation peak amplitude, which is related to reflectivity of a target for a given distance. The switching of the modes may thus be, for instance, decided based on target reflectivity.

[0068] In embodiments with further different internal or external sensors (e.g., radar or IMU (“Inertial Measurement Unit”)), it is also possible to additionally or alternatively use data from all or a subset of these sensors.

[0069] External sensors like radar or IMU may provide another (i.e. their own) distance / velocity estimation and / or other sensor information, e.g., IMU provides acceleration.

[0070] Thus, in some embodiments, the circuitry is configured to switch between the PRCM mode and the CFMCW mode using information of a measurement from an external device.

[0071] In some embodiments, the circuitry is configured to switch between the PRCM mode and the CFMCW mode based on a selection of a user.

[0072] Which information is used to control the switching process may depend on the application and corresponding use cases and may be implemented in several ways.

[0073] For example, for the above-mentioned automotive application, the main distinction between the long-range and short-range use case may be the estimated radial velocities (Doppler frequencies), since the long-range use case may be used for high-speed scenarios (e.g., Autobahn / highway) and the short-range for low-speed scenarios (e.g., parking assistance). For the 3D scanning example, a possible distinction between the large-scale mode and the high-resolution mode may be the estimated average distance in a certain focal area of the 3D scanner, i.e., the distance to the object of interest triggers switching between the modes.Sony Semiconductor Solutions Corporation

[0074] Furthermore, switching the operation mode between CFMCW mode and PRCM mode is independent of the number of LiDAR channels, i.e., this is also valid in case there is only a single channel.

[0075] Generally, the switching concept between CFMCW and PRCM may also be applicable for radar, instead of LiDAR.

[0076] Hence, in some embodiments, the circuitry is configured to switch, based on the distance estimation and / or the velocity estimation and / or amplitude related measurements, between the CFMCW mode and the PRCM mode.

[0077] Generally, at least one distance estimation and / or at least one velocity estimation may indicate a condition to switch between the CFMCW mode and PRCM mode.

[0078] In some embodiments, the circuitry is configured to switch from the PRCM mode to the CFMCW mode when the distance estimation is below a first distance threshold.

[0079] In some embodiments, the circuitry is configured to switch from the CFMCW mode to the PRCM mode when the distance estimation is above a second distance threshold.

[0080] In some embodiments, the circuitry is configured to switch from the PRCM mode to the CFMCW mode when the velocity estimation is below a first velocity threshold.

[0081] In some embodiments, the circuitry is configured to switch from the CFMCW mode to the PRCM mode when the velocity estimation is above a second velocity threshold.

[0082] In some embodiments, the circuitry is configured to switch between the PRCM mode and the CFMCW mode when a certain condition is fulfilled for a preset time.

[0083] The certain condition may be a crossing of a distance threshold or a velocity threshold in either direction by the distance estimation or the velocity estimation, respectively.

[0084] In some embodiments, the circuitry is configured to receive one or more distance thresholds and one or more velocity thresholds from an external application that uses the distance estimations and the velocity estimations.

[0085] Some embodiments pertain to a method for light detection and ranging, wherein the method includes:

[0086] emitting one or more optical beams to a scene;

[0087] receiving one or more reflected optical beams from the scene;

[0088] switching between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein:Sony Semiconductor Solutions Corporation

[0089] in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; and

[0090] in the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.

[0091] The method may be performed by the device as described herein.

[0092] The methods as described herein are also implemented in some embodiments at least in parts as a computer program causing a computer and / or a processor to perform the method, when being carried out on the computer and / or processor. In some embodiments, also a non-transitory computer-readable recording medium is provided that stores therein a computer program product, which, when executed by a processor, such as the processor described above, causes the methods described herein to be performed.

[0093] Returning to Fig. 1, there is schematically illustrated in a block diagram an embodiment of a device 20, which is discussed in the following.

[0094] In this embodiment, the idea is to design a single device, use a single main system parameter set and cover different use cases by switching between the CFMCW mode and the PRCM mode. Fig. 1 shows a top-level architecture embodiment for a switchable multi-mode CFMCW and PRCM based LiDAR device 20. The top-level architecture in Fig. 1 shows the case where the CFMCW mode and the PRCM mode share common main system parameters and only a minimum of control logic is required to switch between the two operation modes. A more complex device and operation may cover more use cases and may be achieved by providing different sets of the main system parameters for the different modes and for the different use cases.

[0095] Generally, in the following for Fig. 1 and Fig. 3, solid arrows indicate optical signals, dotted arrows indicate analog electrical signals, and dashed arrows indicate digital electric signals. The device 20 includes a code generation unit 21, a digital-to-analog converter (“DAC”) unit 22, a modulation unit 23, a FMCW controller 24, a light generator unit 25, a transceiver frontend 26, an analog-to-digital converter (“ADC”) unit 27, a pre-processing unit 28, a data processing unit 29 and a mode controller 40.

[0096] The light generator unit 25 generates one or more optical signals. For example, the light generator unit 25 may include one or more lasers for generating the one or more optical signals. The light generator unit 25 may include a single laser for generating an optical signal and may further include a waveguide to generate multiple copies of the optical signal.Sony Semiconductor Solutions Corporation

[0097] In the CFMCW mode, the FMCW controller 24 applies an electric chirp signal to the laser of the light generator unit 25 such that, for example, the electrical current through the laser is modulated such that the frequency of the emitted optical signal changes over time, for instance, according to a triangular chirp signal including an up-ramp during which the frequency increase linearly over time and a down-ramp during which the frequency decreases linearly over time. Thus, in the CFMCW mode, each of the one or more optical signals generated by the light generator unit 25 is modulated with a frequency chirp signal, for example, the frequency chirp signal is a triangular chirp signal as discussed above.

[0098] In a case in which the mode controller 40 instructs to switch between the CFMCW mode and the PRCM mode, the laser needs to be switched between “FMCW chirp” mode and “PRCM constant carrier” mode, i.e., setting the chirp bandwidth to a certain value or to zero, respectively.

[0099] In any of the operation modes, the code generation unit 21 generates one or more digital individual code signals SCode,m(n) which are supplied to the DAC unit 22 to generate analog individual code signals SCode,m(t) to drive one or more electro-optical modulators of the modulation unit 23 with a respective individual code signal SCode,m(t).

[0100] In the PRCM mode, the light generator unit 25 supplies each of one or more optical signals ELO,Tx,m(t) to one of the one or more electro-optical modulators of the modulation unit 23. The one or more optical signals ET.O Tx m(t) are constant carrier signals, i.e. frequency stable.

[0101] In the CFMCW mode, the one or more optical signals ELO,Tx,m(t) are modulated with a frequency chirp signal as discussed above.

[0102] Then, in the PRCM mode, the modulation unit 23 outputs code modulated optical signals Emod,m(t) to the transceiver frontend 26 which then emits via some optics one or more code modulated optical beams EAir,m(t) to a scene 30.

[0103] In the CFMCW mode, the modulation unit 23 outputs code modulated and frequency chirped optical signals Emod,m(t) to the transceiver frontend 26 which then emits via an optics section one or more code modulated and frequency chirped optical beams EAir,m(t) to the scene 30. The optics section may be adjusted to use two different zoom settings to account for different distance ranges in the two different operation modes or two different optics may be switched to account for the different distance ranges in the different operation modes.Sony Semiconductor Solutions Corporation

[0104] The transceiver frontend 26 then receives the reflected optical beams via the optics section and performs some optical processing (see Fig. 3 below) and photodetection with one or more photodetectors to output one or more electrical signals.

[0105] In the CFMCW mode, the light generator unit 25 supplies one or more optical signals ELO,Rx(t) to the transceiver frontend, wherein each is modulated with a frequency chirp signal, as discussed above. The frequency chirp signal is the same as for the one or more optical signals ELO,Tx,m(t) or frequency offset.

[0106] In the PRCM mode, the light generator unit 25 one or more optical signals ELO,Rx(t) to the transceiver frontend, wherein each is a constant carrier signal, as discussed above.

[0107] The transceiver frontend 26 processing includes optically mixing of the one or more received reflected optical beams with the one of the one or more optical signals ELO,Rx(t).

[0108] Thus, in the CFMCW mode, the one or more electrical signals are electrical beat signals and include the code modulation.

[0109] Thus, in the PRCM mode, the one or more electrical signals only include the code modulation. Generally, the transceiver frontend 26 allows different implementations and variations, for example, the electrical signals may be electrically combined or the received reflected optical beams may be optically combined after or before the optical mixing with the one or more optical signals ELO,Rx(t). In the case of optically combining before the optical mixing, only one optical signal ELO,Rx(t) is needed, since only one optical mixer is needed. Moreover, in the case of optically combining, only one photodetector (e.g., balanced detector) is needed.

[0110] The ADC unit 27 performs analog-to-digital conversion of the one or more electrical signals to digitize the analog receiver signals. In the case of electrical combining of the one or more electric signals in the transceiver frontend 26 is performed before output, only one ADC is needed. Moreover, only one ADC is needed in the case of optically combining. In the case that not electrical combining of the one or more electric signals in the transceiver frontend 26 is performed before output, a number of ADCs corresponding to the number of the one or more emitted (and received) optical beams is provided.

[0111] The digital pre-processing unit 28 performs some calibration and signal format conversion steps corresponding to the implemented architecture. These steps are common for either of theSony Semiconductor Solutions Corporation

[0112] CFMCW mode and the PRCM mode and do not require any switching or parameter adjustment (e.g., when FMCW and PRCM parameters are designed to match the two operation modes). Finally, the data processing unit 29 performs correlation-based LiDAR channel detection and crosstalk reduction and outputs a distance estimation dest and a (radial) velocity estimation vest Even though this is used for the CFMCW mode and the PRCM mode, the exact detector algorithm may slightly differ between the two modes. Thus, the data processing unit 29 typically requires a switching between the modes.

[0113] However, since this is fully digital and the CFMCW mode and PRCM mode share a lot of common functional blocks (e.g., correlation, FFT, etc.), this is an uncritical part to switch and adjust for different operation modes. Typically, it is sufficient for the CFMCW mode to add an additional FMCW based algorithm to obtain the final distance and velocity estimates.

[0114] Then, the mode controller 40 obtains the distance estimation dest and a (radial) velocity estimation vest

[0115] Finally, the obtained distance and / or radial velocity estimates can be used as input for the mode controller 40 for closing the control loop for the mode switching. Based on these estimates and / or other inputs the mode controller 40 may automatically switch the modes (or give indication when to switch between the operation modes).

[0116] If the operation modes require a higher degree of design freedom between the CFMCW mode and PRCM mode and / or more than two operation modes shall be supported, additional control logic and / or memory for system parameter settings are required. For example, if the sampling rate changes between operation modes, the code generation unit 21, the DAC unit 22, the ADC unit 27 and the pre-processing unit 28 may need additional control logic and / or to be initialized with new parameter settings from additional memory. Especially, the code generator unit 21, the pre-processing unit 28 and the data processing unit 29 may require parameter adjustments, e.g., code length, code repetition rate, FFT size, filter coefficients, etc.

[0117] This may increase complexity, memory and speed of switching between the operation modes, however, allows a higher degree of control of the operation modes.

[0118] Application Example:

[0119] PRCM has a limited distance resolution, since the required on-air bandwidth has to be resolved by the receiver.Sony Semiconductor Solutions Corporation

[0120] FMCW can resolve very fine distances at a moderate receiver bandwidth. But FMCW’s computational complexity increases very fast if the maximal distance is increased, while keeping its high distance resolution.

[0121] Thus, a good combination of modes is to use the PRCM mode for long range use cases, typically requiring at most moderate distance resolution, and CFMCW mode for short / medium range use cases, typically requiring much higher distance resolutions.

[0122] Since PRCM and FMCW have very different tasks in CFMCW, they exhibit some degree of freedom to design the respective system parameters. By exploiting this degree of freedom one can for example design the FMCW system parameters such that they have high resolution and accuracy at shorter distance and the PRCM parameters to have lower resolution and accuracy at larger distance. This would allow a switchable device architecture, with a long-range PRCM mode and a short / medium range CFMCW mode, switching the two modes in their sweet-spot operation.

[0123] This allows to use a single LiDAR device (with a single set of common main system parameters) to cover two different use cases by just switching between operation modes.

[0124] For example, it could be used for automotive use cases, where one and the same LiDAR device is used during driving as long-range LiDAR and during parking as short-range parking assistant LiDAR.

[0125] For a joint parameter design for both modes, one needs to connect the two modes via common parameter relations. One example is to define a common ratio between the maximally resolvable distance and the distance resolution (e.g., 500) for both modes, which allows to jointly design the system parameters based on the requirements and this relation.

[0126] An example of the main system requirements and parameters is the following:

[0127] Long range PRCM mode: 300 meters maximum distance, 60 centimeters distance resolution, maximum velocity 200 kilometers per hour.

[0128] Short range CFMCW mode: 10 meters maximum distance, 2 centimeters distance resolution, maximum velocity 30 kilometers per hour.

[0129] Corresponding common main system parameters:

[0130] Code: code repetition 4, code length 8191, cyclic prefix length 2048.

[0131] Measurement time: ca. 88.5 ps.

[0132] FFT size: 16k = 2A14 = 16384.Sony Semiconductor Solutions Corporation

[0133] Sample rate: 1.57 GHz.

[0134] The switching between the two modes may be done based on the estimated velocities of static objects.

[0135] In PRCM mode, static object will have velocities typically well beyond 30 kilometers per hour. In CFMCW mode, static objects will typically be below 30 kilometers per hour, e.g., for parking assistance the car will typically move either very slowly or even stop completely. Based on this, a threshold is defined for switching from short-range to long-range mode (e.g., 50 kilometers per hour) and vice versa (e.g., 20 kilometers per hour). The switching is performed if the estimated velocities cross either threshold for a certain time. In other words, if the velocity estimation is above or below the respective threshold for a certain amount of time such that the mode does not switch immediately to reduce fluctuation of the mode. For example, the velocity estimation may be above or below the respective threshold for a few seconds before the mode is switched.

[0136] Similarly, in the PRCM mode the objects will typically have a higher distance to each other, since the velocities are higher, while in the CFMCW mode the shorter distances are present. However, even at higher velocities some distances may be short for a certain time period.

[0137] Thus, a threshold is defined when to switch from the from short-range to long-range mode (e.g., 20 meters) and vice versa (e.g., 5 meters).

[0138] The switching is performed if the measured distances cross either threshold for a certain time. Fig. 2A schematically illustrates an embodiment of a frequency modulation 10 in the CFMCW mode and the PRCM mode, which is discussed in the following.

[0139] For CFMCW operation either a FMCW chirp signal is generated by a single laser and distributed to each modulator or multiple lasers generate the chirp for each modulator individually. To properly receive the signal, the signal should be evaluated in a valid region, i.e., starting from where the latest possible reflection returns to the receiver until the end of the transmitted ramp. Furthermore, since the code needs to preserve its cyclic conditions for optimal correlation properties, for each code a cyclic prefix (“CP”) is included per ramp. The CP’s minimum length corresponds to the return time of the latest possible reflection.

[0140] In the left graph, a suitable transmission format for the CFMCW mode is shown.

[0141] In the right graph, a suitable transmission format for the PRCM mode is shown.

[0142] A difference between the CFMCW mode and the PRCM mode is that the FMCW carrier is a frequency chirp signal for the CFMCW mode and a constant carrier for the PRCM mode.Sony Semiconductor Solutions Corporation

[0143] Fig. 2B schematically illustrates an embodiment of a frequency modulation 11 in the CFMCW mode and the PRCM mode, which is discussed in the following.

[0144] The embodiment of Fig. 2B is basically the same as the embodiment of Fig. 2A, however, in the embodiment of Fig. 2B multiple code repetitions are included in the individual code signal. Fig. 3 schematically illustrates in a block diagram an embodiment of the transceiver frontend 26 of Fig. 1, which is discussed in the following.

[0145] The transceiver frontend 26 is shown for the case of multiple optical beams to be emitted to the scene 30.

[0146] The transceiver frontend 26 includes a plurality of optical amplifiers 60, a plurality of circulators 61, an optics section 62, a plurality of optical mixers 63 and a plurality of balanced detectors 64. Each of the optical signals Emod,m(t) - either only code modulated (PRCM mode) or code modulated and frequency chirped (CFMCW mode) - is optically amplified by a different optical amplifier 60 to generate the optical signal which is guided through a circulator 61. The

[0147]

[0148] output of the circulator 61 is then emitted via the optics section 62 as an optical beam EAir,m(t) that is modulated according to the individual code signal ECode,m(t) (PRCM mode) or modulated according to the individual code signal ECode,m(t) (CFMCW mode) and a frequency chirp signal.

[0149] The optical amplifiers 60 are generally optional and using them may depend on the distance requirements.

[0150] The emitted optical beam EAir,m(t) may be at least partially reflected in the scene 30 and that part may return to the transceiver frontend 26 and may be received via the optics section 62 which images the reflected optical beam on the respective circulator 61 associated with the emitted optical beam EAir,m(t).

[0151] The transceiver frontend 26 uses a single monostatic optic block (as the optics section 62), i.e., the emitted and received optical beams go through the same optics and are split in transmit and receive path, for example, by the circulator 61.

[0152] Alternatively, the transceiver frontend 26 may use a bistatic optic setup, i.e., dedicated optic transmits the optical beams, and another one receives the reflected optical beams. Such a bistatic optical setup requires a proper calibration of the spatial offset between the two optics but obviates the need for a circulator to split the transmitted and received beams.Sony Semiconductor Solutions Corporation

[0153] Each reflected optical beam then propagates through the circulator 61 which then outputs a received reflected optical beam ERx'.m(t). Each of the received reflected optical beams E Rx m(t) - output by a different circulator 61 - is then optically mixed with the optical signal ELO,Rx(t) in the respective optical mixer 63.

[0154] The optical mixer 63 mixes the received beam with the optical signal ELO,Rx(t), resulting in a code modulated optical signal Emix m(t) for each channel at the receiver.

[0155] In the PRCM mode, Emix,m(t) is only code modulated.

[0156] In the CFMCW mode, Emix (t) is an optical code modulated beat signal. Depending on the realization of the optical mixing, i.e. whether the optical signal ELO,Rx(t) is modulated according to the same frequency chirp signal as ELO,Tx,m(t) or frequency offset, the receiver architecture may correspond to a zero-IF or a low-IF receiver structure, respectively.

[0157] In case the optical mixing is realized, for example with an optical hybrid, the architecture corresponds to a zero-IF receiver, i.e., the same frequency chirp signal is used at the optical mixer 63 and at the modulation unit 23.

[0158] If, for example, a 50 / 50 Coupler is used, the architecture corresponds to a low-IF receiver, i.e., the respective frequency chirp signal has a frequency offset with respect to the frequency chirp signal used at the modulation unit 23.

[0159] The respective optical mixer 63 outputs an optical signal Emjx.m(t) which is detected by a balanced detector 64.

[0160] Hence, each of the balanced detectors 64 outputs an electrical signal which includes the code modulation in the PRCM mode and, in the case of the CFMCW mode, the electrical signal is an electrical beat signals and includes the code modulation.

[0161] Fig. 4 schematically illustrates in a flow diagram an embodiment of a method.

[0162] At 101, one or more optical beams are emitted to a scene, as discussed herein.

[0163] At 102, one or more reflected optical beams are received from the scene, as discussed herein. At 103, the one or more received reflected optical beams are processed to obtain a distance estimation and a velocity estimation for each of the one or more received reflected optical beams, as discussed herein.Sony Semiconductor Solutions Corporation

[0164] At 104, it is switched, based on a distance estimation or a velocity estimation, between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, as discussed herein.

[0165] It should be recognized that the embodiments describe methods with an exemplary ordering of method steps. The specific ordering of method steps is however given for illustrative purposes only and should not be construed as binding.

[0166] In so far as the embodiments of the disclosure described above are implemented, at least in part, using software-controlled data processing apparatus, it will be appreciated that a computer program providing such software control and a transmission, storage or other medium by which such a computer program is provided are envisaged as aspects of the present disclosure.

[0167] Note that the present technology can also be configured as described below.

[0168] (1) A device for light detection and ranging, wherein the device includes circuitry configured to:

[0169] emit one or more optical beams to a scene;

[0170] receive one or more reflected optical beams from the scene;

[0171] switch between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein:

[0172] in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; and

[0173] in the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.

[0174] (2) The device of (1), wherein the circuitry is configured to process the one or more received reflected optical beams to obtain a distance estimation and a velocity estimation for each of the one or more received reflected optical beams.

[0175] (3) The device of (2), wherein the circuitry is configured to switch between the CFMCW mode and the PRCM mode based on information obtained from processing the one or more reflected optical beams.

[0176] (4) The device of (2) or (3), wherein the circuitry is configured to switch, based on the distance estimation and / or the velocity estimation and / or amplitude related measurements, between the CFMCW mode and the PRCM mode.

[0177] (5) The device of (4), wherein the circuitry is configured to switch from the PRCM mode to the CFMCW mode when the distance estimation is below a first distance threshold.Sony Semiconductor Solutions Corporation

[0178] (6) The device of (4) or (5), wherein the circuitry is configured to switch from the CFMCW mode to the PRCM mode when the distance estimation is above a second distance threshold. (7) The device of any one of (4) to (6), wherein the circuitry is configured to switch from the PRCM mode to the CFMCW mode when the velocity estimation is below a first velocity threshold.

[0179] (8) The device of any one of (4) to (7), wherein the circuitry is configured to switch from the CFMCW mode to the PRCM mode when the velocity estimation is above a second velocity threshold.

[0180] (9) The device of any one of (4) to (8), wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode when a certain condition is fulfilled for a preset time. (10) The device of any one of (4) to (9), wherein the circuitry is configured to receive one or more distance thresholds and one or more velocity thresholds from an external application that uses the distance estimations and the velocity estimations.

[0181] (11) The device of any one of (1) to (10), wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode using information of a measurement from an external device.

[0182] (12) The device of any one of (1) to (11), wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode based on a selection of a user.

[0183] (13) The device of any one of (1) to (12), wherein the circuitry is configured to use a common set of main system parameters in the PRCM mode and in the CFMCW mode.

[0184] (14) The device of (13), wherein the common set of main system parameters are the individual code signals, a measurement time, a sample rate and a data block size for Fast-Fourier Transform.

[0185] (15) A method for light detection and ranging, wherein the method includes:

[0186] emitting one or more optical beams to a scene;

[0187] receiving one or more reflected optical beams from the scene;

[0188] switching between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein:

[0189] in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; and

[0190] in the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.Sony Semiconductor Solutions Corporation

[0191] (16) The method of (15), including processing the one or more received reflected optical beams to obtain a distance estimation and a velocity estimation for each of the one or more received reflected optical beams.

[0192] (17) The method of (16), including switching between the CFMCW mode and the PRCM mode based on information obtained from processing the one or more reflected optical beams. (18) The method of any one of (16), including switching, based on the distance estimation or the velocity estimation, between the CFMCW mode and the PRCM mode.

[0193] (19) The method of (18), including switching from the PRCM mode to the CFMCW mode when the distance estimation is below a first distance threshold.

[0194] (20) The method of (18) or (19), including switching from the CFMCW mode to the PRCM mode when the distance estimation is above a second distance threshold.

[0195] (21) The method of any one of (18) to (20), including switching from the PRCM mode to the CFMCW mode when the velocity estimation is below a first velocity threshold.

[0196] (22) The method of any one of (18) to (21), including switching from the CFMCW mode to the PRCM mode when the velocity estimation is above a second velocity threshold.

[0197] (23) The method of any one of (18) to (22), including switching between the PRCM mode and the CFMCW mode when a certain condition is fulfilled for a preset time.

[0198] (24) The method of any one of (18) to (23), including receiving one or more distance thresholds and one or more velocity thresholds from an external application that uses the distance estimations and the velocity estimations.

[0199] (25) The method of any one of (15) to (24), wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode using information of a measurement from an external device.

[0200] (26) The method of any one of (15) to (25), wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode based on a selection of a user.

[0201] (27) The method of any one of (15) to (26), including using a common set of main system parameters in the PRCM mode and in the CFMCW mode.

[0202] (28) The method of (27), wherein the common set of main system parameters are the individual code signals, a measurement time, a sample rate and a data block size for Fast-Fourier Transform.

Claims

Sony Semiconductor Solutions CorporationCLAIMS1. A device for light detection and ranging, comprising circuitry configured to:emit one or more optical beams to a scene;receive one or more reflected optical beams from the scene;switch between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein:in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; andin the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.

2. The device of claim 1, wherein the circuitry is configured to process the one or more received reflected optical beams to obtain a distance estimation and a velocity estimation for each of the one or more received reflected optical beams.

3. The device of claim 2, wherein the circuitry is configured to switch between the CFMCW mode and the PRCM mode based on information obtained from processing the one or more reflected optical beams.

4. The device of claim 2, wherein the circuitry is configured to switch, based on the distance estimation and / or the velocity estimation and / or amplitude related measurements, between the CFMCW mode and the PRCM mode.

5. The device of claim 4, wherein the circuitry is configured to switch from the PRCM mode to the CFMCW mode when the distance estimation is below a first distance threshold.

6. The device of claim 4, wherein the circuitry is configured to switch from the CFMCW mode to the PRCM mode when the distance estimation is above a second distance threshold.

7. The device of claim 4, wherein the circuitry is configured to switch from the PRCM mode to the CFMCW mode when the velocity estimation is below a first velocity threshold.

8. The device of claim 4, wherein the circuitry is configured to switch from the CFMCW mode to the PRCM mode when the velocity estimation is above a second velocity threshold.

9. The device of claim 4, wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode when a certain condition is fulfilled for a preset time.Sony Semiconductor Solutions Corporation10. The device of claim 2, wherein the circuitry is configured to receive one or more distance thresholds and one or more velocity thresholds from an external application that uses the distance estimations and the velocity estimations.

11. The device of claim 1, wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode using information of a measurement from an external device.

12. The device of claim 1, wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode based on a selection of a user.

13. The device of claim 1, wherein the circuitry is configured to use a common set of main system parameters in the PRCM mode and in the CFMCW mode.

14. The device of claim 13, wherein the common set of main system parameters are the individual code signals, a measurement time, a sample rate and a data block size for Fast-Fourier Transform.

15. A method for light detection and ranging, comprising:emitting one or more optical beams to a scene;receiving one or more reflected optical beams from the scene;switching between a coded frequency modulated continuous wave mode, CFMCW mode, and a pseudo random code modulation mode, PRCM mode, wherein:in the PRCM mode, each of the one or more emitted optical beams is modulated with an individual code signal; andin the CFMCW mode, each of the one or more emitted optical beams is modulated with an individual code signal and a frequency chirp signal.

16. The method of claim 15, comprising processing the one or more received reflected optical beams to obtain a distance estimation and a velocity estimation for each of the one or more received reflected optical beams.

17. The method of claim 16, comprising switching between the CFMCW mode and the PRCM mode based on information obtained from processing the one or more reflected optical beams.

18. The method of claim 16, comprising switching, based on the distance estimation and / or the velocity estimation and / or amplitude related measurements, between the CFMCW mode and the PRCM mode.

19. The method of claim 18, comprising switching from the PRCM mode to the CFMCW mode when the distance estimation is below a first distance threshold.Sony Semiconductor Solutions Corporation20. The method of claim 18, comprising switching from the CFMCW mode to the PRCM mode when the distance estimation is above a second distance threshold.

21. The method of claim 18, comprising switching from the PRCM mode to the CFMCW mode when the velocity estimation is below a first velocity threshold.

22. The method of claim 18, comprising switching from the CFMCW mode to the PRCM mode when the velocity estimation is above a second velocity threshold.

23. The method of claim 18, comprising switching between the PRCM mode and the CFMCW mode when a certain condition is fulfilled for a preset time.

24. The method of claim 18, comprising receiving one or more distance thresholds and one or more velocity thresholds from an external application that uses the distance estimations and the velocity estimations.

25. The method of claim 15, wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode using information of a measurement from an external device.

26. The method of claim 15, wherein the circuitry is configured to switch between the PRCM mode and the CFMCW mode based on a selection of a user.

27. The method of claim 15, comprising using a common set of main system parameters in the PRCM mode and in the CFMCW mode.

28. The method of claim 27, wherein the common set of main system parameters are the individual code signals, a measurement time, a sample rate and a data block size for Fast-Fourier Transform.

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