Asymmetric frequency division multiplexing for radar systems

Abstract

This document describes techniques and systems for asymmetric frequency division multiplexing (FDM) for radar systems. In some examples, a radar system includes multiple transmitters, multiple receivers, multiple polyphase shifters, and a processor. The transmitters can transmit electromagnetic (EM) signals in an FDM scheme. The receivers can receive EM signals reflected by one or more objects that include multiple channels. The polyphase shifters can introduce at least four potential phase shifts. The processor can control the polyphase shifters to introduce phase shifts that are asymmetrically spaced in the frequency spectrum. The processor can use residual estimation and subtraction to determine potential detections of the objects. In this way, the described asymmetric FDM for radar systems can support many simultaneous MIMO channels, increase the dynamic range of the radar system, resolve Doppler ambiguities, and provide an efficient processing scheme.

Description

Background Technology

[0001] Radar systems transmit and receive electromagnetic (EM) signals for object detection and tracking. In automotive applications, radar systems provide information about the vehicle's environment and can play a crucial role in advanced driver assistance systems (ADAS). Highly automated systems typically require high-resolution radar data in terms of range, Doppler, and angular dimensions. A popular approach to achieving improved angular dimensions is multiple-input multiple-output (MIMO) radar technology, which provides a relatively large virtual array with reduced angular ambiguity, capable of forming a virtual array larger than the physical aperture. However, depending on the waveform, MIMO technology can lead to reduced dynamic range and / or insufficient range or Doppler coverage, among other issues. Summary of the Invention

[0002] This document describes techniques and systems for asymmetric frequency division multiplexing (FDM) for radar systems. In some examples, radar systems mounted on vehicles include multiple transmitters, multiple receivers, multiple phase shifters, and a processor. The transmitters can transmit electromagnetic (EM) signals in an FDM scheme. The receivers can receive EM signals, including multiple channels, reflected by one or more objects. The phase shifters can introduce at least four potential phase shifts into the transmitted or received EM signals. The phase shifters are operatively connected to either the transmitter or the receiver. The processor can control the phase shifters to introduce phase shifts asymmetrically spaced in the spectrum. The processor can use residual estimation and subtraction to determine the potential detection of objects. In this way, the described asymmetric FDM for radar systems can support many simultaneous MIMO channels, increase the dynamic range of the radar system, resolve Doppler ambiguity, and provide an efficient processing scheme.

[0003] This document also describes the methods performed by the systems summarized above and other configurations of the radar systems described herein, as well as the apparatus for performing these methods.

[0004] This invention provides a simplified concept related to enabling asymmetric FDM technology in radar systems, which is further described in the detailed description and accompanying drawings. This invention is not intended to identify essential features of the claimed subject matter, nor is it intended to define the scope of the claimed subject matter. Attached Figure Description

[0005] This document describes in detail one or more aspects of asymmetric FDM for radar systems with reference to the following figures. The same numbers are generally used throughout the figures to refer to similar features and components:

[0006] Figure 1 An example environment in which a radar system can use asymmetric FDM according to the technology of this disclosure is shown;

[0007] Figure 2 An example configuration of a radar system using asymmetric FDM within a vehicle, according to the technology of this disclosure, is shown;

[0008] Figure 3 , Figure 4-1 as well as Figure 4-2 An example conceptual diagram of a radar system using asymmetric FDM is shown;

[0009] Figure 5 An example graphical representation of waveforms in a radar system using asymmetric FDM is shown;

[0010] Figure 6 An example method for determining the Doppler frequency of an object using an asymmetric FDM via a multiphase shifter is shown; and

[0011] Figures 7-1 to 7-7 The Doppler spectrum from a radar system that uses asymmetric FDM to determine the detection associated with an object is shown. Detailed Implementation

[0012] Overview

[0013] Radar systems can be configured as an important sensing technology used by vehicle-based systems to acquire information about their surroundings. For example, vehicle-based systems can use radar systems to detect objects in or near the road and take necessary actions (e.g., reduce speed, change lanes) to avoid collisions.

[0014] Radar systems typically include at least two antennas to transmit and receive radar (e.g., EM) signals. Many vehicle-based systems require high resolution in terms of range, Doppler frequency, and angle. These systems also require the accurate differentiation of multiple targets with similar Doppler frequencies. These requirements are often addressed by including more antenna channels in the radar system. For example, some automotive radar systems operate as MIMO radars to increase the number of channels and improve angular resolution. A MIMO radar system with three transmit channels and four receive channels can form a virtual array (also known as a "synthetic array") of twelve channels. Utilizing the additional channels, MIMO radar systems can operate with improved angular resolution, relying on a flexible physical layout that is inexpensive and may require fewer hardware components than traditional non-MIMO radar systems.

[0015] MIMO radar systems typically use orthogonal waveforms to transmit and receive independent orthogonal EM signals, and to identify or separate different channels. Radar systems can implement orthogonal waveforms in various ways, including using time-division multiplexing (TDM), FDM, and code-division multiplexing (CDM) techniques. However, each orthogonal waveform technique has its associated advantages and disadvantages.

[0016] For example, FDM technology typically places signals from the transmit channel into different frequency bands by adding a frequency offset to the transmitted signal. Such techniques generally operate in the fast time (range) domain, introducing range-dependent phase shifts between channels and reducing range coverage. Due to the increased intermediate frequency bandwidth, FDM technology may also require a higher sampling rate.

[0017] CDM (Chip-Device Modeling) technology enables simultaneous transmission and operation in both the fast time domain (e.g., within the chirp and range domains) and the slow time domain (e.g., chirp-to-chirp, Doppler domain). CDM typically recovers a signal matching the current encoding by suppressing energy from other encoded signals. The distributed EM energy left from the suppressed signal is generally considered residual energy or noise and limits the dynamic range of the radar system. A smaller dynamic range limits the radar system's ability to distinguish between smaller and larger objects.

[0018] Some TDM techniques do not support simultaneous transmission. Instead, individual transmitters transmit sequentially, resulting in less interference between transmission channels and achieving maximum orthogonality. However, such techniques typically cannot provide the signal-to-noise ratio advantage achieved with simultaneous transmission techniques (e.g., FDM and CDM) and may lead to Doppler blurring between channels.

[0019] Previous techniques (including those described above) typically do not provide sufficient differentiation between channels (e.g., Doppler blurring, target mixing) and may have reduced Doppler coverage, gain, and dynamic range. Furthermore, these techniques often require computationally expensive processing to support a large number of MIMO channels.

[0020] In contrast, this document describes techniques and systems for providing radar systems that utilize FDM and coding techniques to achieve simultaneous transmission and provide multiple MIMO channels. This document also describes efficient processing techniques to provide improved dynamic range. In this way, when using more MIMO channels, the described techniques and systems support simultaneous transmission from multiple transmitters with accurate recovery and increased dynamic range.

[0021] For example, a radar system for a vehicle includes multiple transmitters, multiple receivers, multiple phase shifters, and a processor. The transmitters can transmit EM signals in an FDM scheme. The receivers can receive EM signals, including multiple channels, reflected from one or more objects. The phase shifters can introduce multiple potential phase shifts into the transmitted or received EM signals. The processor can control the phase shifters to introduce asymmetric phase shifts. The processor can use incoherent integration and residual extraction on the received EM signals to determine potential object detection. In this way, simultaneous transmission from multiple transmitters is supported, with accurate recovery and increased dynamic range.

[0022] This example is just one illustration of the techniques and systems used in a radar system employing asymmetric FDM. Other examples and implementations are described in this document.

[0023] Operating environment

[0024] Figure 1 An example environment 100 in which the radar system 104 can use asymmetric FDM according to the technology of this disclosure is shown. In the depicted environment 100, the radar system 104 is mounted to or integrated into a vehicle 102 traveling on a road 106. Within a field of view 108, the radar system 104 can detect one or more objects 110 in the vicinity of the vehicle 102.

[0025] Radar system 104 can detect one or more objects 110 in the vicinity of vehicle 102. Although shown as a car, vehicle 102 can represent other types of motorized vehicles (e.g., cars, automobiles, motorcycles, buses, tractors, semi-trailers), non-motorized vehicles (e.g., bicycles), rail vehicles (e.g., trains), water vehicles (e.g., boats), and aircraft (e.g., airplanes). Typically, manufacturers can mount radar system 104 to any mobile platform, including mobile machinery or robotic equipment.

[0026] In the depicted implementation, radar system 104 is mounted on the front of vehicle 102 and illuminates object 110. Radar system 104 can detect object 110 from any external surface of vehicle 102. For example, vehicle manufacturers can integrate radar system 104 into bumpers, side mirrors, headlights, taillights, or any other internal or external location where object 110 needs to be detected. In some cases, vehicle 102 includes multiple radar systems 104, such as a first radar system 104 and a second radar system 104 providing a larger field of view 108. Generally, vehicle manufacturers can design the placement of radar systems 104 to provide a specific field of view 108 encompassing a region of interest. Example fields of view 108 include 360-degree fields of view, one or more 180-degree fields of view, one or more 90-degree fields of view, etc., which can overlap or be combined to form a field of view 108 of a specific size.

[0027] Object 110 is made of one or more materials that reflect radar or EM signals. Depending on the application, object 110 may represent a target of interest. In some cases, object 110 may be a moving object (e.g., another vehicle) or a stationary object (e.g., a roadside sign, road obstacle, debris). Depending on the application, object 110 may represent a target of interest, which vehicle 102 can use to safely navigate on road 106.

[0028] Radar system 104 emits EM radiation by transmitting EM signals or waveforms via antenna elements. For example, in environment 100, radar system 104 can detect and track object 110 by transmitting and receiving one or more EM signals. For example, radar system 104 can transmit EM signals between 100 and 400 GHz, between 4 and 100 GHz, or between approximately 70 and 80 GHz.

[0029] Radar system 104 may be a MIMO radar system capable of matching reflected EM signals to a corresponding object 110. Radar system 104 may include a transmitter 112 for transmitting EM signals. Radar system 104 may also include a reflective version of a receiver 114 for receiving EM signals. Transmitter 112 includes one or more components, including an antenna or antenna element, for transmitting EM signals. Receiver 114 includes one or more components, including an antenna or antenna element, for detecting reflected EM signals. Transmitter 112 and receiver 114 may be integrated together on the same integrated circuit (e.g., a transceiver integrated circuit) or separately on different integrated circuits. In other implementations, radar system 104 does not include separate antennas, but transmitter 112 and receiver 114 each include one or more antenna elements.

[0030] The radar system 104 may also include a polyphase shifter 116. The polyphase shifter 116 is associated with and operatively connected to either the transmitter 112 or the receiver 114. In some applications, the polyphase shifter 116 may apply a phase shift to one or more signal pulses of an EM signal transmitted by the transmitter 112. In other implementations, the polyphase shifter 116 may apply a phase shift to one or more signal pulses of a reflected EM signal received by the receiver 114.

[0031] The radar system 104 also includes one or more processors 118 (e.g., energy processing units) and a computer-readable storage medium (CRM) 120. The processor 118 may be a microprocessor or a system-on-a-chip. The processor 118 can execute instructions stored in the CRM 120. For example, the processor 118 can process EM energy received by the receiver 114 and use a spectrum analysis module 122 and an incoherent integrator 124 to determine the position of the object 110 relative to the radar system 104. The processor 118 can also detect various characteristics of the object 110 (e.g., range, target angle, rate of change of range, velocity). The processor 118 may include instructions or be configured to control the transmitter 112, the receiver 114, or the multiphase shifter 116. The processor 118 is also capable of generating radar data for at least one vehicle system. For example, the processor 118 can control the autonomous or semi-autonomous driving system of the vehicle 102 based on the processed EM energy from the receiver 114.

[0032] The spectrum analysis module 122 allows multiple channels in the received EM signal to resolve Doppler ambiguity between the received EM signals. Specifically, the spectrum analysis module 122 can estimate and remove residuals from targets detected in the Doppler spectrum of the received EM signal. In this way, the spectrum analysis module 122 can suppress residuals close to the noise floor and improve the detection dynamic range of the radar system 104. This document is about Figures 6 to 7-7 The operation and functions of the spectrum analysis module 122 are described in more detail. The radar system 104 may implement the spectrum analysis module 122 as instructions executed by the processor 118 in the form of CRM 120, hardware, software, or a combination thereof.

[0033] The incoherent integrator 124 can process the EM energy received by the receiver 114 to identify the object 110 (e.g., from a detected target) and resolve Doppler ambiguity associated with the object 110 within the field of view 108 of the radar system 104. The incoherent integrator 124 can use a ring-shift and summation scheme to reject aliased detections and resolve Doppler ambiguity, as discussed in... Figures 6 to 7-7As described in more detail. The radar system 104 can implement the incoherent integrator 124 as a CRM 120, hardware, software, or a combination thereof, as instructions executed by the processor 118.

[0034] The described radar system 104 facilitates simultaneous transmission of multiple transmitter channels in a MIMO radar system with a multiphase shifter 116. The described aspects of asymmetric FDM support simultaneous transmission by multiple transmitters 112 with accurate recovery and no Doppler ambiguity. Accurate recovery is possible because interference between channels is prevented (e.g., avoided), and Doppler ambiguity is resolved to reject aliasing detection.

[0035] As an example environment Figure 1 The diagram illustrates a vehicle 102 traveling on a road 106. A radar system 104 detects an object 110 in front of the vehicle 102. The radar system 104 may define a coordinate system with an x-axis (e.g., in the forward direction along the road 106) and a y-axis (e.g., perpendicular to the x-axis and along the surface of the road 106), and in some cases, further define a z-axis (e.g., perpendicular to the xy-plane defined by the x-axis and y-axis). A transmitter 112 of the radar system 104 may emit an EM signal in front of the vehicle 102. The object 110 may reflect the emitted EM signal as a reflected EM signal. A receiver 114 may detect the reflected EM signal.

[0036] Vehicle 102 may also include at least one vehicle system, such as a driver assistance system, autonomous driving system, or semi-autonomous driving system, that relies on data from radar system 104. Radar system 104 may include an interface that interfaces with the vehicle system that relies on the data. For example, processor 118 outputs a signal based on EM energy received by receiver 114 via this interface.

[0037] Typically, automotive systems use radar data provided by radar system 104 to perform functions. For example, a driver assistance system may provide blind spot monitoring and generate an alert indicating a potential collision with object 110 detected by radar system 104. In such implementations, radar data from radar system 104 indicates when changing lanes is safe or unsafe. An autonomous driving system may move vehicle 102 to a specific location on road 106 while avoiding a collision with object 110 detected by radar system 104. The radar data provided by radar system 104 can provide information about the distance to and position of object 110, enabling the autonomous driving system to perform emergency braking, lane changes, or adjust the speed of vehicle 102.

[0038] Radar system 104 operates using efficient processing techniques to provide improved dynamic range. In this way, when using more MIMO channels, radar system 104 can support simultaneous transmission from multiple transmitters with accurate recovery and increased dynamic range.

[0039] Figure 2 An example configuration of a radar system using asymmetric FDM within a vehicle 102 according to the technology of this disclosure is shown. The vehicle 102 may include a driving system 206, including an autonomous driving system 208 or a semi-autonomous driving system 210, which uses radar data from the radar system 104 to control the vehicle 102. (See also: Regarding...) Figure 1 As described, the vehicle 102 may include a radar system 104.

[0040] The vehicle may also include one or more sensors 202, one or more communication devices 204, and a driving system 206. Sensors 202 may include position sensors, cameras, lidar systems, or combinations thereof. For example, a position sensor may include a positioning system capable of determining the position of vehicle 102. A camera system may be mounted on or near the front of vehicle 102. The camera system may capture photographic images or videos of road 106. In other implementations, a portion of the camera system may be mounted in a rearview mirror of vehicle 102 to have a field of view of road 106. In yet another implementation, the camera system may project a field of view from any external surface of vehicle 102. For example, a vehicle manufacturer may integrate at least a portion of the camera system into a side mirror, bumper, roof, or any other internal or external location where the field of view includes road 106. The lidar system may use electromagnetic signals to detect objects 110 (e.g., other vehicles) on road 106. Data from the lidar system may be provided as input to a spectrum analysis module 122 or an incoherent integrator 124. For example, a lidar system can determine the speed of a vehicle in front of vehicle 102 or the speed of a nearby vehicle traveling in the same direction as vehicle 102.

[0041] Communication device 204 may be an RF transceiver for transmitting and receiving radio frequency (RF) signals. The transceiver may include one or more transmitters and receivers, which may be integrated together on the same integrated circuit (e.g., a transceiver integrated circuit) or separately on different integrated circuits. Communication device 204 may be used to communicate with: remote computing devices (e.g., servers or computing systems providing navigation information or area speed limit information), nearby structures (e.g., construction zone traffic signs, traffic lights, school zone traffic signs), or nearby vehicles. For example, vehicle 102 may use communication device 204 to wirelessly exchange information with nearby vehicles using vehicle-to-vehicle (V2V) communication. Vehicle 102 may use V2V communication to obtain the speed, position, and heading of nearby vehicles. Similarly, vehicle 102 may use communication device 204 to wirelessly receive information from nearby traffic signs or structures indicating temporary speed limits, traffic congestion, or other traffic-related information.

[0042] The communication device 204 may include a sensor interface and a driving system interface. The sensor interface and the driving system interface may transmit data between the radar system 104 and the driving system 206 via the communication bus of the vehicle 102, for example.

[0043] The vehicle 102 also includes at least one driving system 206, such as an autonomous driving system 208 or a semi-autonomous driving system 210, which relies on data from the radar system 104 to control the operation of the vehicle 102 (e.g., setting a driving speed or avoiding object 110). Typically, the driving system 206 uses data provided by the radar system 104 and / or sensors 202 to control the vehicle 102 and perform specific functions. For example, the semi-autonomous driving system 210 may provide adaptive cruise control and dynamically adjust the speed of the vehicle 102 based on the presence of object 110 in front of it. In this example, data from the radar system 104 may identify object 110 and its speed relative to the vehicle 102.

[0044] The autonomous driving system 208 can navigate the vehicle 102 to a specific destination while avoiding objects 110 identified by the radar system 104. Data about the object 110 provided by the radar system 104 can provide information about the position and / or speed of the object 110, enabling the autonomous driving system 208 to adjust the speed of the vehicle 102.

[0045] Example configuration

[0046] Figure 3An example concept diagram 300 of a radar system 302 using asymmetric FDM is shown. For example, radar system 302 could be... Figure 1 and Figure 2 Radar system 104. Conceptual diagram 300 illustrates the components of radar system 302 as different components, but some or all of them can be combined into a smaller subset of different components.

[0047] In the depicted implementation, radar system 302 includes a plurality of transmitters 304 (shown as antenna elements in this example) configured to transmit corresponding EM signals. Radar system 302 uses the transmitted EM signals to detect any object 110 in the vicinity of vehicle 102 and within field of view 108. In some implementations, transmitters 304 may transmit linear frequency modulated signals (e.g., chirped signals). In other implementations, transmitters 304 may transmit phase-modulated continuous wave (PMCW) signals or pulsed signals (e.g., unmodulated signals). The transmitted EM signals can be any feasible signals for a radar system. Radar system 302 also includes a plurality of receivers 306 (shown as antenna elements in this example) configured to receive reflected EM signals reflected by object 110.

[0048] Radar system 302 includes a processor and a CRM, the processor and CRM can be respectively Figure 1 and Figure 2 The processor 118 and CRM 120 are included. The CRM includes instructions that, when executed by the processor, cause the processor to control the transmitter 304 or the phase shifter 308. For example, the processor can use the spectrum analysis module 122 to control the phase shift applied to or introduced into the transmitted EM.

[0049] In the example shown, radar system 302 includes a voltage-controlled oscillator (VCO) 312 operatively coupled to transmitter 304. VCO 312 provides a base or reference signal for the EM signal transmitted by transmitter 304. Multiple phase shifters 308 are associated with and coupled to transmitter 304 and VCO 312, respectively. In the depicted implementation, phase shifters 308 are operatively coupled to each transmitter 304. In other implementations, phase shifters 308 may be operatively coupled to fewer than each transmitter 304.

[0050] The multiphase shifter 308 can control the phase shift applied to or introduced into one or more EM signal pulses emitted by the transmitter 304. Each multiphase shifter 308 has multiple potential output stages (e.g., 4 stages, 8 stages, 16 stages, 32 stages, 64 stages, 128 stages, or 256 stages). For example, a processor can provide a multiphase control signal 310 to the multiphase shifter 308 to control or set the phase stage of each multiphase shifter 308. The multiphase control signal 310 can be a multi-bit signal (e.g., 6-bit, 8-bit, 12-bit, 16-bit, 24-bit, or 32-bit), thereby allowing the multiphase shifter 308 to have more than two phase stages. For example, a six-bit multiphase shifter 308 has up to 64 potential phase stages. The increased number of potential phase stages provides greater flexibility in the FDM coding scheme applied by the radar system 302 than that offered by binary phase shifters. The polyphase control signal 310 can add a progressive phase modulation φ to the transmitted EM signal pulse, which causes the frequency or Doppler frequency of the reflected EM signal to be asymmetrically shifted by a frequency ω. c The offset frequency ω c Equals the product of 2, π, and phase modulation (e.g., ω). c =2πφ).

[0051] As described above, receiver 306 receives the reflected EM signal. Radar system 302 processes the received EM signal to make one or more determinations relating to object 110 within the field of view 108 of radar system 302. Receiver 306 is operatively coupled to a corresponding low-noise amplifier (LNA) 314. LNA 314 amplifies the received EM signal without significantly reducing the signal-to-noise ratio. LNA 314 is operatively coupled to a corresponding mixer 316, which is coupled to VCO 312. The output of VCO 312 is used as a reference signal and combined with the corresponding received EM signal in mixer 316. Radar system 302 passes the corresponding received EM signals through bandpass filter (BPF) 318 and analog-to-digital converter (ADC) 320 before analyzing them with digital signal processor (DSP) 322. DSP 322 can make one or more determinations relating to object 110, including resolving Doppler ambiguity. BPF 318 allows frequencies within a specific range of the received EM signal to pass through and rejects or attenuates frequencies outside that range. In other implementations, radar system 302 may use additional or different filters, including low-pass or high-pass filters. ADC 320 converts the analog EM signal into a digital signal. DSP 322 may use incoherent integrator 124 to resolve Doppler ambiguity and identify the Doppler frequencies associated with object 110. Although DSP 322 is shown as a component separate from the processor, radar system 302 may include a single processor that controls the transmission of EM signals and makes determinations based on the reception of EM signals.

[0052] Figure 4-1 and Figure 4-2 Further example concept diagrams 400 and 410 are shown for radar systems 402 and 412 using asymmetric FDM, respectively. For example, radar systems 402 and 412 could be... Figure 1 and Figure 2 Radar system 104. Conceptual diagrams 400 and 410 illustrate the components of radar systems 402 and 412 as different components, but some or all of them can be combined into a smaller subset of different components.

[0053] Radar systems 402 and 412 include those targeting Figure 3The components depicted in radar system 302 are similar to those in other radar systems. For example, radar systems 402 and 412 include a transmitter 304, a receiver 306, a processor, a CRM, a polyphase shifter 308, a VCO 312, an LNA 314, a mixer 316, a BPF 318, an ADC 320, and a DSP 322. The polyphase shifter 308 is operatively coupled to the LNA 314 and mixer 316 in the receiver paths of radar systems 402 and 412 to asymmetrically shift the frequency, or Doppler frequency, of the reflected EM signal. Figure 4-1 In this configuration, the multiphase shifter 308 is operatively coupled to each receive channel and subsequently operatively coupled to a single down-conversion or analog-to-digital conversion channel. Figure 4-2 In this configuration, the polyphase shifter 308 is operatively coupled to each receive channel, and the receive channel or a subset of the polyphase shifters 308 is subsequently operatively coupled to a down-conversion or analog-to-digital conversion channel. As shown in conceptual diagram 410, for each down-conversion or analog-to-digital conversion channel, the radar system 412 includes two polyphase shifters 308 or receive channels. In other implementations, for each down-conversion or analog-to-digital conversion channel, the radar system 412 may include another number of polyphase shifters 308 or receive channels, thereby generating N receive groups, each with M receive channels.

[0054] The polyphase shifter 308 can also be operatively coupled between other components in the receiver path, including between receiver 306 and LNA 314. The polyphase shifter 308 is not operatively coupled to transmitter 304, but is associated with receiver 306 separately. The polyphase shifter 308 can introduce or apply an asymmetric phase shift to the received EM signal. Radar system 402 or 412 can combine (e.g., superimpose) the signals received by one or more receivers in receiver 306 before analog-to-digital conversion by ADC 320.

[0055] As described above, each multiphase shifter 308 has multiple potential output stages (e.g., 4, 8, 16, 32, 64, 128, or 256 stages). For example, processor 118 can provide multiphase control signals 310 to multiphase shifters 308 to control or set the phase stages of each multiphase shifter 308. The multiphase control signals 310 can be multi-bit signals (e.g., 6-bit, 8-bit, 12-bit, 16-bit, 24-bit, or 32-bit), thus giving multiphase shifters 308 more than two phase stages. The increased number of potential phase stages provides greater flexibility in the FDM encoding scheme applied by radar system 402 to the received EM signal than that offered by binary phase shifters. The multiphase control signals 310 can add a progressive phase modulation φ to the received EM signal pulse, causing the frequency or Doppler frequency of the reflected EM signal to be asymmetrically shifted by an offset frequency ω. c The offset frequency ω c Equals the product of 2, π, and phase modulation (e.g., ω). c =2πφ).

[0056] Figure 5 An example graphical representation 500 of waveforms in a radar system using asymmetric FDM is shown. For example, the radar system could be... Figure 1 and Figure 2 Radar system 104 Figure 3 Radar system 302, Figure 4-1 Radar system 402, or Figure 4-2 Radar system 412.

[0057] The graphical representation 500 shows the energy of the received EM signal on the y-axis and the corresponding Doppler frequency of the received EM signal on the x-axis. The received EM signal includes N channels 502, which in... Figure 5 The peaks are represented by triangular peaks corresponding to the actual detection or aliasing detection within each channel.

[0058] Radar system 104 applies asymmetric Doppler spectral spacing to the transmitted or received EM signals to provide a fully asymmetric waveform. Each channel 502 operates at a Doppler frequency 504 (D) in the Doppler spectrum. i (For example, Doppler frequencies 504-1, 504-2, 504-3, 504-(N-1), 504-N) are separated. For example, the first channel 502-1 and the second channel 502-2 are separated by the Doppler frequency 504-1 (D1). The asymmetric Doppler spectrum results in each Doppler frequency 504 having a unique value (e.g., D1≠D2≠D3≠D...). N-1 ≠D NIf the peaks from two different objects are mixed in the Doppler spectrum, only one channel 502 from each object is mixed, resulting in a signal-to-interference ratio of approximately N or an interference-to-signal ratio of 1 / N.

[0059] When cyclic shifting is applied to the channels, the asymmetric Doppler spectrum provides non-overlapping codes. Channel placement can be selected using a modular Golomb ruler or a random search. For example, the received EM signal may include four channels located in the spectrum at the product of twice π divided by 16 (2π / 16) and 0, 2, 5, and 6, or their cyclic shift equivalents. As another example, the received EM signal may include six channels located in the spectrum at the product of twice π divided by 64 (2π / 64) and 0, 16, 20, 33, 38, and 39, or their cyclic shift equivalents. In yet another example, the received EM signal may include eight channels located in the spectrum at the product of twice π divided by 64 (2π / 64) and 0, 4, 5, 17, 19, 25, 28, and 35, or their cyclic shift equivalents. In yet another example, the received EM signal may include twelve channels, which are located in the spectrum and are respectively the product of twice π divided by 256 (2π / 256) and 0, 17, 44, 67, 158, 161, 163, 167, 174, 199, 219, and 238, or their cyclically shifted equivalents. In yet another example, the received EM signal may include sixteen channels, which are located in the spectrum and are respectively the product of twice π divided by 512 (2π / 512) and 0, 1, 16, 30, 37, 40, 81, 92, 115, 123, 135, 219, 223, 236, 241, and 268, or their cyclically shifted equivalents. In yet another example, the received EM signal may include 24 channels, which are located in the spectrum as products of twice π divided by 1024 (2π / 1024) and 0, 9, 33, 37, 38, 97, 122, 129, 140, 142, 152, 191, 205, 208, 252, 278, 286, 326, 332, 353, 368, 384, 403, and 425, or their cyclically shifted equivalents. In yet another example, the received EM signal may include 32 channels, which are located in the spectrum as products of twice π divided by 2048 (2π / 2048) and 0, 7, 15, 26, 28, 57, 112, 118, 136, 176, 177, 181, 211, 214, 258, 309, 318, 341, 389, 403, 456, 476, 512, 528, 582, 628, 671, 696, 745, 762, 772, and 784, or their cyclically shifted equivalents.

[0060] When cyclic shifting is applied to the channels, the asymmetric Doppler spectrum provides non-overlapping codes. Channel placement can be selected using a modular Gronhurst or a random search. For example, the received EM signal may include four channels located in the spectrum at the product of twice π divided by 16 (2π / 16) and 0, 2, 5, and 6, or their cyclic shift equivalents. As another example, the received EM signal may include six channels located in the spectrum at the product of twice π divided by 64 (2π / 64) and 0, 2, 20, 33, 38, and 39, or their cyclic shift equivalents. In yet another example, the received EM signal may include eight channels located in the spectrum at the product of twice π divided by 64 (2π / 64) and 0, 4, 5, 17, 19, 25, 28, and 35, or their cyclic shift equivalents. In yet another example, the received EM signal may include twelve channels, which are located in the spectrum and are respectively the product of twice π divided by 256 (2π / 256) and 0, 17, 44, 67, 158, 161, 163, 167, 174, 199, 219, and 238, or their cyclically shifted equivalents. In yet another example, the received EM signal may include sixteen channels, which are located in the spectrum and are respectively the product of twice π divided by 512 (2π / 512) and 0, 1, 16, 30, 37, 40, 81, 92, 115, 123, 135, 219, 223, 236, 241, and 268, or their cyclically shifted equivalents. As yet another example, the received EM signal may include 24 channels, which are located in the spectrum as products of twice π divided by 1024 (2π / 1024) and 0, 9, 33, 37, 38, 97, 122, 129, 140, 142, 152, 191, 205, 208, 252, 278, 286, 326, 332, 353, 368, 384, 403, and 425, or their cyclically shifted equivalents. In yet another example, the received EM signal may include 32 channels, which are located in the spectrum as products of twice π divided by 2048 (2π / 2048) and 0, 7, 15, 26, 28, 57, 112, 118, 136, 176, 177, 181, 211, 214, 258, 309, 318, 341, 389, 403, 456, 476, 512, 528, 582, 628, 671, 696, 745, 762, 772, and 784, or their cyclically shifted equivalents.

[0061] Table 1

[0062]

[0063] Example Method

[0064] Figure 6 An example method 600 for a radar system using asymmetric FDM via a multiphase shifter is illustrated. Method 600 is shown as multiple sets of operations (or actions) performed, but is not limited to the order or combination of operations shown herein. Furthermore, any one or more operations may be repeated, combined, or recombined to provide other methods. References may be made in the sections discussed below. Figure 1 Environment 100 and Figures 1 to 5 The entities detailed herein are referred to by way of example only. This technology is not limited to being performed by one or more entities. For example, a radar system could be... Figure 1 and Figure 2 Radar system 104 Figure 3 Radar system 302, Figure 4-1 Radar system 402 or Figure 4-2 The radar system 412 determines the Doppler frequency of an object 110 around the vehicle 102.

[0065] At position 602, the EM signal is transmitted by multiple transmitters of the radar system in an FDM scheme. For example, transmitter 304 can transmit the EM signal in an FDM scheme.

[0066] At 604, EM signals reflected by one or more objects are received by multiple receivers of the radar system. For example, receiver 306 may receive EM signals reflected by object 110. Object 110 may reflect EM signals transmitted by transmitter 304. The received EM signals include a number of channels equal to the product of the number of transmitters (e.g., a first number) and the number of receivers (e.g., a second number). The second number may be equal to or different from the first number. The received EM signals include a third number of channels, which is equal to the product of the first and second numbers. The channels are asymmetrically spaced in the Doppler spectrum. Multiple transmitters and multiple receivers may be configured to operate as part of a MIMO radar method.

[0067] Modular Gronz rulers can be used to place channels in the spectrum. For example, a received EM signal may include four channels located in the spectrum, each calculated as the product of twice π divided by 16 (2π / 16) and 0, 2, 5, and 6, or their cyclically shifted equivalents. As another example, a received EM signal may include six channels located in the spectrum, each calculated as the product of twice π divided by 64 (2π / 64) and 0, 16, 20, 33, 38, and 39, or their cyclically shifted equivalents. In yet another example, a received EM signal may include eight channels located in the spectrum, each calculated as the product of twice π divided by 64 (2π / 64) and 0, 4, 5, 17, 19, 25, 28, and 35, or their cyclically shifted equivalents. In yet another example, the received EM signal may include twelve channels, which are located in the spectrum and are respectively the product of twice π divided by 256 (2π / 256) and 0, 17, 44, 67, 158, 161, 163, 167, 174, 199, 219, and 238, or their cyclically shifted equivalents. In yet another example, the received EM signal may include sixteen channels, which are located in the spectrum and are respectively the product of twice π divided by 512 (2π / 512) and 0, 1, 16, 30, 37, 40, 81, 92, 115, 123, 135, 219, 223, 236, 241, and 268, or their cyclically shifted equivalents. In yet another example, the received EM signal may include 24 channels, which are located in the spectrum as products of twice π divided by 1024 (2π / 1024) and 0, 9, 33, 37, 38, 97, 122, 129, 140, 142, 152, 191, 205, 208, 252, 278, 286, 326, 332, 353, 368, 384, 403, and 425, or their cyclically shifted equivalents. In yet another example, the received EM signal may include 32 channels, which are located in the spectrum as products of twice π divided by 2048 (2π / 2048) and 0, 7, 15, 26, 28, 57, 112, 118, 136, 176, 177, 181, 211, 214, 258, 309, 318, 341, 389, 403, 456, 476, 512, 528, 582, 628, 671, 696, 745, 762, 772, and 784, or their cyclically shifted equivalents.

[0068] At 606, multiple phase shifters are controlled to introduce a phase shift into the transmitted or received EM signal. The multiple phase shifters are operatively connected to multiple transmitters or receivers of the radar system. Each phase shifter includes one of at least four potential phase shifts that are asymmetrically spaced in the spectrum. For example, phase shifter 308 is operatively connected to transmitter 304 or receiver 306. Radar system 104 may include a fourth number of phase shifters. This fourth number may be equal to or different from the first or second number. Processor 118 can control phase shifter 308 to introduce a phase shift into the transmitted and / or received EM signal, wherein the phase shift includes one of at least four potential phase shifts. As described above, processor 118 can control phase shifter 308 using phase control signal 310. The multiphase control signal 310 can be a multi-bit signal (e.g., 6-bit, 8-bit, 12-bit, 16-bit, 24-bit, or 32-bit), thus allowing the multiphase shifter 308 to have more than two phase stages. In the coding scheme applied to the transmitted or received EM signals, the increased number of potential phase stages provides greater flexibility than that offered by binary phase shifters. Furthermore, potential phase stages allow the radar system 104 to utilize asymmetric FDM schemes.

[0069] At position 608, the Doppler spectrum of the received EM signal is determined. For example, the spectrum analysis module 122 or the radar system 104 can determine the Doppler spectrum of the received EM signal. The spectrum analysis module 122 can generate an estimated EM signal Doppler spectrum for the peak and subtract it from the Doppler spectrum.

[0070] At 610, incoherent integration (NCI) can be performed on the received EM signal to generate an NCI spectrum. For example, incoherent integrator 124 or radar system 104 can perform NCI on the received EM signal to generate an NCI spectrum. Incoherent integration can be performed by performing cyclic shifts on the Doppler spectrum to align MIMO channels that have been shifted or placed in the Doppler spectrum of the received EM signal through asymmetric coding. Assuming that the first channel (or one of the channels) is not waveform-shifted, the number of cyclic shifts performed can be equal to the number of channels minus one. Incoherent integrator 124 or radar system 104 can determine the sum of EM energy levels at each Doppler bin across the Doppler spectrum of the received EM signal and the additional EM spectrum. Asymmetric coding in the Doppler spectrum of the received EM signal results in no alignment of spurious peaks after cyclic shifts.

[0071] At position 612, the detection threshold for the NCI spectrum can be estimated using the location of the cyclically shifted channel. For example, the incoherent integrator 124 or radar system 104 can use the location of the cyclically shifted channel to estimate the detection threshold for the NCI spectrum. The detection threshold for the NCI spectrum can be estimated by determining the average EM energy level at a specific Doppler frequency point in the Doppler spectrum. The specific Doppler cell is located at the location of the cyclically shifted channel. Because spurious peaks are misaligned or overlapped after the cyclic shift, the detection dynamic range of radar system 104 is improved.

[0072] At 614, one or more objects are identified as one or more potential detectors above the detection threshold. For example, DSP 322 or processor 118 can identify potential detectors associated with object 110 having EM energy above the detection threshold.

[0073] Then, the spectrum analysis module 122, DSP 322, or processor 118 can reconstruct the Doppler spectrum of one or more potential detectors to generate a detection Doppler spectrum, and subtract the detection Doppler spectrum from the Doppler spectrum of the received EM signal to generate an updated multi-frequency spectrum of the received EM signal. The DSP 322 or processor 118 can use the updated Doppler spectrum to identify one or more additional potential detectors.

[0074] The DSP 322 or processor 118 can identify one or more additional potential detections by performing NCI on the updated Doppler spectrum to generate an updated NCI spectrum. An updated detection threshold for the updated NCI spectrum can be estimated using the location of the channel after cyclic shifting. The DSP 322 or processor 118 can then identify one or more additional potential detections above the updated detection threshold. The DSP 322 or processor 118 can repeat these steps until the updated Doppler spectrum does not include EM energy or potential detections above the updated detection threshold. For example, the DSP 322 or processor 118 can determine whether the updated Doppler spectrum does not include potential detections above the updated detection threshold. If so, the DSP 322 or processor 118 can stop or terminate the iterative process to identify additional potential detections.

[0075] At 618, the Doppler frequency associated with each of one or more objects is determined based on latent detection. For example, DSP 322 or processor 118 can determine the Doppler frequency associated with object 110 based on latent detection.

[0076] Figures 7-1 to 7-7 The Doppler spectrum 700 from a radar system that uses asymmetric FDM to determine the detection associated with an object is shown. For example, the radar system could be... Figure 1 and Figure 2 Radar system 104 Figure 3 Radar system 302, Figure 4-1 Radar system 402 or Figure 4-2 The radar system 412 determines the detection of objects 110 around the vehicle 102.

[0077] Figure 7-1 The Doppler spectrum 700-1 of an exemplary received EM signal is shown. The radar system 104 includes eight channels in the received EM signal, each channel having a six-bit polyphase shifter 308. The channels are located in the spectrum, respectively, as products of twice π divided by 64 (2π / 64) and 0, 4, 5, 17, 19, 25, 28, and 35. The Doppler spectrum 700-1 includes peaks in the EM energy associated with the first target 702-1, the second target 702-2, and the third target 702-3. The Doppler spectrum 700-1 also includes a ghost peak from target 702.

[0078] Figure 7-2 The Doppler spectrum 700-2 is shown, which represents the estimated EM signal Doppler spectrum of the peaks in the Doppler spectrum 700-1. The radar system 104 can identify the peaks in the Doppler spectrum 700-1 and extract the estimated EM signal associated with them. Figure 7-3 The Doppler spectrum 700-3 is shown. The Doppler spectrum 700-3 is generated by subtracting the Doppler spectrum 700-2 from the Doppler spectrum 700-1.

[0079] Figure 7-4 The Doppler spectrum 700-4 is shown, representing the Doppler spectrum after performing incoherent integration across the channels of the received EM signal. Incoherent integration can be performed by cyclically shifting the Doppler spectrum 700-3 and summing the resulting Doppler spectrum. The number of cyclic shifts performed can be equal to the number of channels minus one. In Doppler spectrum 700-4, the EM energies associated with the first target 702-1 and the third target 702-3 are above the detection threshold 704. The residual level in Doppler spectrum 700-4 is suppressed compared to the peaks associated with the first target 702-1 and the third target 702-3. The EM energy associated with the second target 702-2 is below the detection threshold, and therefore the second target 703-2 is not identified in the iterations of the incoherent integration.

[0080] The incoherent integrator 124 or radar system 104 can use the positions of the eight channels after cyclic shifting to estimate the detection threshold 704 and determine the average EM energy level at the Doppler chamber associated with the channel positions in the Doppler spectrum.

[0081] Figure 7-5 The Doppler spectrum 700-5 is shown, representing the Doppler spectrum after a second iteration of incoherent integration across the channel of the received EM signal. After identifying the first target 702-1 and the third target 702-3, the spectrum analysis module 122, DSP 322, or processor 118 can then reconstruct the Doppler spectrum 700-1 for the first target 702-1 and the third target 702-3, and subtract the associated Doppler spectrum from the Doppler spectrum 700-1 of the received EM signal to generate an updated multi-frequency spectrum. The DSP 322 or processor 118 can use the updated Doppler spectrum to identify one or more additional potential detections (e.g., a second target 702-2) by performing additional iterations of incoherent integration until no additional target is identified. In the Doppler spectrum 700-5, the EM energy associated with the second target 702-2 is higher than the detection threshold 706. Compared to the Doppler spectrum 700-4, the residual level in the Doppler spectrum 700-3 is further suppressed.

[0082] Figure 7-6 Doppler spectrum 700-6 is shown, representing the Doppler spectrum after the third iteration of incoherent integration across the channel of the received EM signal. After identifying the second target 702-2, the spectrum analysis module 122, DSP 322, or processor 118 can then reconstruct the Doppler spectrum 700-1 for the second target 702-2 and subtract the associated Doppler spectrum from the Doppler spectrum 700-1 of the received EM signal to generate an updated multi-frequency spectrum. In Doppler spectrum 700-6, no peaks above the detection threshold 708 are identified. Compared to Doppler spectrum 700-5, the residual level in Doppler spectrum 700-6 is further suppressed.

[0083] Figure 7-7 The Doppler spectrum 700-7 is shown, indicating the Doppler frequencies associated with the first target 702-1, the second target 702-2, and the third target 702-3.

[0084] Example

[0085] Examples are provided in the following sections.

[0086] Example 1. A radar system comprising: a plurality of transmitters configured to transmit electromagnetic (EM) signals in a frequency division multiplexing (FDM) scheme; a plurality of receivers configured to receive EM signals reflected by one or more objects; a plurality of polyphase shifters operatively connected to the plurality of transmitters or receivers, the plurality of polyphase shifters being configured to introduce at least one of four potential phase shifts asymmetrically spaced in a frequency spectrum; and a processor configured to control the plurality of polyphase shifters to introduce at least one of the at least four potential phase shifts into at least one of the transmitted or received EM signals.

[0087] Example 2. The radar system of Example 1, wherein: a plurality of transmitters include a first number of transmitters; a plurality of receivers include a second number of receivers, the second number being equal to or not equal to the first number; a plurality of multiphase shifters include a third number of multiphase shifters, the third number being equal to or not equal to the first number; and the received EM signals include a fourth number of channels, the fourth number being equal to the product of the first number and the second number.

[0088] Example 3. The radar system of Example 2, wherein: a plurality of multiphase shifters are operatively connected to a plurality of transmitters; and a third number equals the first number.

[0089] Example 4. The radar system of Example 2, wherein: a plurality of multiphase shifters are operatively connected to a plurality of receivers; and a third number equals the second number.

[0090] Example 5. A radar system of any of Examples 2 to 4, wherein a modular goron ruler is used to place the channel of the received EM signal in the spectrum.

[0091] Example 6. A radar system of any one of Examples 2 to 5, wherein: the fourth quantity is equal to four; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 16 (2π / 16) and 0, 2, 5 and 6, or their cyclic shift equivalents.

[0092] Example 7. A radar system of any one of Examples 2 to 5, wherein: the fourth quantity is equal to six; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 64 (2π / 64) and 0, 16, 20, 33, 38 and 39, or their cyclic shift equivalents.

[0093] Example 8. A radar system of any one of Examples 2 to 5, wherein: the fourth quantity is equal to eight; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 64 (2π / 64) and 0, 4, 5, 17, 19, 25, 28 and 35, or their cyclic shift equivalents.

[0094] Example 9. A radar system of any one of Examples 2 to 5, wherein: the fourth quantity is equal to twelve; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 256 (2π / 256) and 0, 17, 44, 67, 158, 161, 163, 167, 174, 199, 219 and 238, or their cyclically shifted equivalents.

[0095] Example 10. A radar system of any one of Examples 2 to 5, wherein: the fourth quantity is equal to sixteen; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 512 (2π / 512) and 0, 1, 16, 30, 37, 40, 81, 92, 115, 123, 135, 219, 223, 236, 241 and 268, or their cyclically shifted equivalents.

[0096] Example 11. A radar system of any one of Examples 2 to 5, wherein: the fourth quantity is equal to 24; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 1024 (2π / 1024) and 0, 9, 33, 37, 38, 97, 122, 129, 140, 142, 152, 191, 205, 208, 252, 278, 286, 326, 332, 353, 368, 384, 403 and 425, or their cyclically shifted equivalents.

[0097] Example 12. A radar system of any one of Examples 2 to 5, wherein: the fourth quantity is equal to 32; and the channel of the received EM signal is located in the spectrum, respectively, by dividing π by 2048 (2π / 2048) by the product of 0, 7, 15, 26, 28, 57, 112, 118, 136, 176, 177, 181, 211, 214, 258, 309, 318, 341, 389, 403, 456, 476, 512, 528, 582, 628, 671, 696, 745, 762, 772 and 784, or their cyclically shifted equivalents.

[0098] Example 13. Any of the radar systems in the previous examples, wherein multiple transmitters and multiple receivers are configured to operate as part of a multiple-input multiple-output (MIMO) radar method.

[0099] Example 14. Any of the radar systems in the previous examples, wherein the radar system is configured for mounting on a vehicle.

[0100] Example 15. A computer-readable storage medium comprising computer-executable instructions, which, when executed, cause a processor of a radar system to: transmit electromagnetic (EM) signals in a frequency division multiplexing (FDM) scheme via a plurality of transmitters of the radar system; receive EM signals reflected by one or more objects via a plurality of receivers of the radar system; and control a plurality of polyphase shifters for introducing a phase shift into at least one of the transmitted or received EM signals, the plurality of polyphase shifters being operatively connected to the plurality of transmitters or receivers, the introduced phase shift including one of at least four potential phase shifts asymmetrically spaced in the spectrum.

[0101] Example 16. The computer-readable storage medium of Example 15, wherein: a plurality of transmitters include a first number of transmitters; a plurality of receivers include a second number of receivers, the second number being equal to or not equal to the first number; a plurality of multiphase shifters include a third number of multiphase shifters, the third number being equal to or not equal to the first number; and the received EM signal includes a fourth number of channels, the fourth number being equal to the product of the first number and the second number.

[0102] Example 17. A computer-readable storage medium of Example 16, wherein a modular globular ruler is used to place the channel of the received EM signal in the spectrum.

[0103] Example 18. A computer-readable storage medium of Example 16 or 17, wherein: the fourth quantity is equal to six; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 64 (2π / 64) and 0, 16, 20, 33, 38 and 39, or their cyclic shift equivalents.

[0104] Example 19. A computer-readable storage medium of Example 16 or 17, wherein: the fourth quantity is equal to eight; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 64 (2π / 64) and 0, 4, 5, 17, 19, 25, 28 and 35, or their cyclic shift equivalents.

[0105] Example 20. A computer-readable storage medium of Example 16 or 17, wherein: the fourth quantity is equal to twelve; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 256 (2π / 256) and 0, 17, 44, 67, 158, 161, 163, 167, 174, 199, 219 and 238, or their cyclically shifted equivalents.

[0106] Example 21. A method comprising: transmitting an electromagnetic (EM) signal in a frequency division multiplexing (FDM) scheme via a plurality of transmitters of a radar system; receiving an EM signal reflected by one or more objects via a plurality of receivers of the radar system; and controlling a plurality of polyphase shifters for introducing a phase shift into at least one of the transmitted or received EM signals, the plurality of polyphase shifters being operatively connected to the plurality of transmitters or receivers, the introduced phase shift including one of at least four potential phase shifts asymmetrically spaced in the spectrum.

[0107] Example 22. A radar system comprising: a first number of receivers configured to receive electromagnetic (EM) signals reflected by one or more objects, the EM signals being transmitted by a second number of transmitters in a frequency division multiplexing (FDM) scheme, the second number being equal to or not equal to the first number, the received EM signals including a third number of channels, the third number being equal to the product of the first and second numbers, the received EM signals including asymmetrically spaced phase shifts between the channels in a spectrum; and a processor configured to: determine the Doppler spectrum of the received EM signals; perform incoherent integration (NCI) on the received EM signals to generate an NCI spectrum; estimate a detection threshold for the NCI spectrum using the positions of the channels after cyclic shifting; identify one or more potential detections of the one or more objects above the detection threshold; and determine a Doppler frequency associated with each of the one or more objects based on the potential detections.

[0108] Example 23. The radar system of Example 22, wherein: phase shift is introduced by a first number of multiphase shifters operably connected to the receiver.

[0109] Example 24. The radar system of Example 22, wherein: the phase shift is introduced by a second number of multiphase shifters operably connected to the transmitter.

[0110] Example 25. A radar system of any one of Examples 22 to 24, wherein the processor is configured to perform NCI on a received EM signal by the following steps: performing a specific number of cyclic shifts on the Doppler spectrum to align channels in the Doppler spectrum of the received EM signal, the specific number being equal to a third number minus one; and determining the sum of EM energy levels at each Doppler compartment across the Doppler spectrum and the additional Doppler spectrum of the received EM signal.

[0111] Example 26. A radar system of any of Examples 22 to 25, wherein the processor is configured to estimate a detection threshold for the NCI spectrum by determining the average EM energy level at a specific Doppler compartment of the Doppler spectrum, the specific Doppler compartment being located at the channel location.

[0112] Example 27. A radar system of any one of Examples 22 to 26, wherein the processor is further configured to: reconstruct the Doppler spectrum of one or more potential detectors to generate a detection Doppler spectrum; subtract the detection Doppler spectrum from the Doppler spectrum of the received EM signal to generate an updated Doppler spectrum of the received EM signal; and identify one or more additional potential detectors using the updated Doppler spectrum.

[0113] Example 28. A radar system of Example 27, wherein the processor is configured to identify one or more additional potential detections by the following steps: performing incoherent integration (NCI) on the updated Doppler spectrum to generate an updated NCI spectrum; using the location of the channel to estimate an updated detection threshold for the updated NCI spectrum; and identifying one or more additional potential detections above the updated detection threshold.

[0114] Example 29. A radar system of Example 28, wherein the processor is further configured to: determine whether the updated Doppler spectrum does not include additional potential detections above the updated detection threshold; and in response to determining that the updated Doppler spectrum does not include additional potential detections above the updated detection threshold, terminate the process for identifying one or more additional potential detections.

[0115] Example 30. A radar system of any of Examples 22 to 29, wherein: the third quantity is equal to four; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 16 (2π / 16) and 0, 2, 5 and 6, or their cyclic shift equivalents.

[0116] Example 31. A radar system of any one of Examples 22 to 29, wherein: the third quantity is equal to six; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 64 (2π / 64) and 0, 16, 20, 33, 38 and 39, or their cyclic shift equivalents.

[0117] Example 32. A radar system of any of Examples 22 to 29, wherein: the third quantity is equal to eight; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 64 (2π / 64) and 0, 4, 5, 17, 19, 25, 28 and 35, or their cyclically shifted equivalents.

[0118] Example 33. A radar system of any one of Examples 22 to 29, wherein: the third quantity is equal to twelve; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 256 (2π / 256) and 0, 17, 44, 67, 158, 161, 163, 167, 174, 199, 219 and 238, or their cyclically shifted equivalents.

[0119] Example 34. A radar system of any one of Examples 22 to 29, wherein: the third quantity is equal to sixteen; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 512 (2π / 512) and 0, 1, 16, 30, 37, 40, 81, 92, 115, 123, 135, 219, 223, 236, 241 and 268, or their cyclically shifted equivalents.

[0120] Example 35. A radar system of any one of Examples 22 to 29, wherein: the third quantity is equal to 24; and the channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 1024 (2π / 1024) and 0, 9, 33, 37, 38, 97, 122, 129, 140, 142, 152, 191, 205, 208, 252, 278, 286, 326, 332, 353, 368, 384, 403 and 425, or their cyclically shifted equivalents.

[0121] Example 36. A radar system of any one of Examples 22 to 29, wherein: the fourth quantity is equal to 32; and the channel of the received EM signal is located in the spectrum, respectively, by dividing π by 2048 (2π / 2048) by the product of 0, 7, 15, 26, 28, 57, 112, 118, 136, 176, 177, 181, 211, 214, 258, 309, 318, 341, 389, 403, 456, 476, 512, 528, 582, 628, 671, 696, 745, 762, 772 and 784, or their cyclically shifted equivalents.

[0122] Example 37. A radar system of any of Examples 22 to 36, wherein the transmitter and receiver operate as part of a multiple-input multiple-output (MIMO) radar method.

[0123] Example 38. A radar system of any of Examples 22 to 37, wherein the radar system is configured for installation on a vehicle.

[0124] Example 39. A computer-readable storage medium comprising computer-executable instructions, which, when executed, cause a processor of a radar system to: receive, via a first number of receivers, electromagnetic (EM) signals reflected by one or more objects, the EM signals being transmitted by a second number of transmitters in a frequency division multiplexing (FDM) scheme, the second number being equal to or not equal to the first number, the received EM signals including a third number of channels, the third number being equal to the product of the first number and the second number, the received EM signals including asymmetrically spaced phase shifts between the channels in a spectrum; determine the Doppler spectrum of the received EM signals; perform incoherent integration (NCI) on the received signals to generate an NCI spectrum; estimate a detection threshold for the NCI spectrum using the positions of the channels after cyclic shifting; identify one or more potential detections of the one or more objects above the detection threshold; and, based on the potential detections, determine a Doppler frequency associated with each of the one or more objects.

[0125] Example 40. A method comprising: receiving, via a first number of receivers, an electromagnetic (EM) signal reflected by one or more objects, the EM signal being transmitted by a second number of transmitters in a frequency division multiplexing (FDM) scheme, the second number being equal to or not equal to the first number, the received EM signal including a third number of channels, the third number being equal to the product of the first number and the second number, the received EM signal including asymmetrically spaced phase shifts between the channels in a spectrum; determining the Doppler spectrum of the received EM signal; performing incoherent integration (NCI) on the received signal to generate an NCI spectrum; estimating a detection threshold for the NCI spectrum using the positions of the channels after cyclic shifting; identifying one or more potential detections of the one or more objects above the detection threshold; and determining, based on the potential detections, a Doppler frequency associated with each of the one or more objects.

[0126] Example 41. The method of Example 40, wherein performing NCI on the received EM signal includes: performing a specific number of cyclic shifts on the Doppler spectrum to align channels in the Doppler spectrum of the received EM signal, the specific number being equal to a third number minus one; and determining the sum of EM energy levels at each Doppler compartment across the Doppler spectrum and the additional Doppler spectrum of the received EM signal.

[0127] Example 42. The method of Example 40 or 41, wherein the method further comprises: reconstructing the Doppler spectrum of one or more potential detectors to generate a detection Doppler spectrum; subtracting the detection Doppler spectrum from the Doppler spectrum of the received EM signal to generate an updated Doppler spectrum of the received EM signal; and using the updated Doppler spectrum to identify one or more additional potential detectors.

[0128] Conclusion

[0129] While various embodiments of the present disclosure have been described in the foregoing description and illustrated in the accompanying drawings, it should be understood that the present disclosure is not limited thereto, but can be practiced in various ways within the scope of the following claims. It will be apparent from the foregoing description that various modifications can be made without departing from the scope of the present disclosure as defined by the following claims.

Claims

1. A radar system, the radar system comprising: Multiple transmitters configured to transmit electromagnetic (EM) signals in a frequency division multiplexing (FDM) scheme; Multiple receivers, the multiple receivers being configured to receive EM signals reflected by one or more objects; A plurality of multiphase shifters operatively connected to the plurality of transmitters or the plurality of receivers, the plurality of multiphase shifters being configured to introduce at least one of four potential phase shifts, the potential phase shifts being asymmetrically spaced in the spectrum; A processor configured to: control the plurality of multiphase shifters to introduce one of at least four potential phase shifts into at least one of the transmitted or received EM signals, and wherein the processor is configured to apply a progressive phase modulation added to the transmitted EM signal pulses, which causes the frequency or Doppler frequency of the reflected EM signal to be asymmetrically shifted by a shift frequency ω c , the shift frequency ω c equal to the product of two, pi, and the progressive phase modulation ω c = 2 π .

2. The radar system as described in claim 1, characterized in that: The plurality of transmitters includes a first number of transmitters; The plurality of receivers includes a second number of receivers, which may or may not be equal to the first number; The plurality of multiphase shifters includes a third number of multiphase shifters, the third number being equal to the first number or the second number; and The received EM signal includes a fourth number of channels, which is equal to the product of the first number and the second number.

3. The radar system as described in claim 2, characterized in that: The plurality of multiphase shifters are operatively connected to the plurality of transmitters; and The third quantity is equal to the first quantity.

4. The radar system as described in claim 2, characterized in that: The plurality of multiphase shifters are operatively connected to the plurality of receivers; and The third quantity is equal to the second quantity.

5. The radar system of claim 2, wherein, A modular goron ruler is used to place the channel of the received EM signal in the spectrum.

6. The radar system as described in claim 2, characterized in that: The fourth quantity is equal to four; and The channel of the received EM signal is located in the spectrum, which is the product of twice π divided by 16 (2π / 16) and 0, 2, 5 and 6, or their cyclic shift equivalents.

7. The radar system as described in claim 2, characterized in that: The fourth quantity is equal to six; and The channel of the received EM signal is located in the spectrum, which is the product of twice π divided by 64 (2π / 64) and 0, 16, 20, 33, 38 and 39, or their cyclic shift equivalents.

8. The radar system as described in claim 2, characterized in that: The fourth quantity is equal to eight; and The channel of the received EM signal is located in the spectrum, which is the product of twice π divided by 64 (2π / 64) and 0, 4, 5, 17, 19, 25, 28 and 35, or their cyclic shift equivalents.

9. The radar system as described in claim 2, characterized in that: The fourth quantity is equal to twelve; and The channel of the received EM signal is located in the spectrum, which is respectively the product of twice π divided by 256 (2π / 256) and 0, 17, 44, 67, 158, 161, 163, 167, 174, 199, 219 and 238, or their cyclic shift equivalents.

10. The radar system as described in claim 2, characterized in that: The fourth quantity equals sixteen; and The channel of the received EM signal is located in the spectrum, which is the product of twice π divided by 512 (2π / 512) and 0, 1, 16, 30, 37, 40, 81, 92, 115, 123, 219, 223, 236, 241 and 268, or their cyclic shift equivalents.

11. The radar system as described in claim 2, characterized in that: The fourth quantity is equal to 24; and The channel of the received EM signal is located in the spectrum, respectively in the product of twice π divided by 1024 (2π / 1024) and 0, 9, 33, 37, 38, 97, 122, 129, 140, 142, 152, 191, 205, 208, 252, 278, 286, 326, 332, 353, 368, 384, 403 and 425, or their cyclic shift equivalents.

12. The radar system as described in claim 2, characterized in that: The fourth quantity is equal to 32; and The channel of the received EM signal is located in the spectrum, respectively, as a product of twice π divided by 2048 (2π / 2048) and 0, 7, 15, 26, 28, 57, 112, 118, 136, 176, 177, 181, 211, 214, 258, 309, 318, 341, 389, 403, 456, 476, 512, 528, 582, 628, 671, 696, 745, 762, 772 and 784, or their cyclic shift equivalents.

13. The radar system of claim 1, wherein, The plurality of transmitters and the plurality of receivers are configured to operate as part of a multiple-input multiple-output (MIMO) radar method.

14. The radar system of claim 1, wherein, The radar system is configured for installation on a vehicle.

15. A computer-readable storage medium comprising computer-executable instructions, which, when executed, cause a processor of a radar system to: Electromagnetic (EM) signals are transmitted via multiple transmitters of the radar system using a frequency division multiplexing (FDM) scheme; The radar system receives EM signals reflected from one or more objects via multiple receivers. A plurality of multiphase shifters are controlled to introduce a phase shift into at least one of the transmitted or received EM signals, the plurality of multiphase shifters being operatively connected to the plurality of transmitters or the plurality of receivers, the introduced phase shift including one of at least four potential phase shifts asymmetrically spaced in the spectrum, and Progressive phase modulation This is added to the emitted EM signal pulse, causing an asymmetrical frequency shift in the reflected EM signal, or Doppler frequency. ω c The offset frequency ω c Equals the product of 2, π, and the progressive phase modulation. ω c =2 π .

16. The computer-readable storage medium as claimed in claim 15, characterized in that: The plurality of transmitters includes a first number of transmitters; The plurality of receivers includes a second number of receivers, which may or may not be equal to the first number; The plurality of multiphase shifters includes a third number of multiphase shifters, the third number being equal to the first number or the second number; and The received EM signal includes a fourth number of channels, which is equal to the product of the first number and the second number.

17. The computer-readable storage medium of claim 16, wherein, A modular goron ruler is used to place the channel of the received EM signal in the spectrum.

18. The computer-readable storage medium as claimed in claim 16, characterized in that: The fourth quantity is equal to four; and The channel of the received EM signal is located in the spectrum, which is the product of twice π divided by 16 (2π / 16) and 0, 2, 5 and 6, or their cyclic shift equivalents.

19. The computer-readable storage medium as claimed in claim 16, characterized in that: The fourth quantity is equal to six; and The channel of the received EM signal is located in the spectrum, which is the product of twice π divided by 64 (2π / 64) and 0, 16, 20, 33, 38 and 39, or their cyclic shift equivalents.

20. A method comprising: Electromagnetic (EM) signals are transmitted via multiple transmitters in a frequency division multiplexing (FDM) scheme through the radar system; The radar system receives EM signals reflected from one or more objects via multiple receivers. A plurality of multiphase shifters are controlled to introduce a phase shift into at least one of the transmitted or received EM signals, the plurality of multiphase shifters being operatively connected to the plurality of transmitters or receivers, the introduced phase shift including one of at least four potential phase shifts asymmetrically spaced in the spectrum, and adding to the transmitted EM signal pulse an asymmetric frequency shift equal to a product of two, pi, and the progressive phase modulation ω c , the shift frequency ω c equal to a product of two, pi, and the progressive phase modulation ω c =2 π .

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