Frequency division multiplexing with polyphase shifters

Abstract

This document describes techniques and systems for frequency division multiplexing (FDM) with a polyphase shifter. A radar system can include a transmitter, a receiver, a polyphase shifter, and a processor. The transmitter transmits electromagnetic (EM) signals in an FDM scheme, and the receiver detects EM signals reflected by an object. The received EM signals include multiple channels. The processor controls the polyphase shifter to introduce phase shifts to the EM signals. The processor can also divide a Doppler spectrum of the received EM signals into multiple sectors representing respective frequency ranges. Each channel is associated with a respective sector. The processor can determine potential detections, including aliasing detections and actual detections, of the object using non-coherent integration across the sectors. The processor can then determine the actual detections. In this way, the described FDM techniques with a polyphase shifter can resolve Doppler ambiguities in the received EM signals.

Description

BACKGROUND

[0001] Radar systems transmit and receive electromagnetic (EM) signals for detecting and tracking objects. In automotive applications, radar systems provide information about the environment of a vehicle and can play an important role in advanced driver assistance systems (ADAS). Highly automated systems often require radar data with high resolution in range, Doppler, and angular dimensions. A popular method to achieve improved angular dimension is multiple-input and multiple-output (MIMO) radar technology, which provides a relatively large virtual array with reduced angular ambiguity. However, MIMO technology can provide insufficient Doppler discrimination. SUMMARY

[0002] This document describes techniques and systems for frequency division multiplexing (FDM) with polyphase shifters. In some examples, a radar system for installation on a vehicle includes a plurality of transmitters, a plurality of receivers, a plurality of 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, including a plurality of channels. The polyphase shifters can introduce at least three potential phase shifts into the transmitted EM signals, the received EM signals, or both. The polyphase shifters are operatively connected to the transmitters, the receivers, or a combination of both. The processor can control the polyphase shifters to introduce the phase shifts. The processor can also divide a Doppler spectrum of the received EM signals into a plurality of sectors representing respective frequency ranges. Each channel is associated with a respective sector. The processor can determine potential detections of objects using non-coherent integration of the received EM signals across the sectors. The processor can subsequently determine actual detections. In this way, the described FDM techniques with polyphase shifters can resolve Doppler ambiguities in the received EM signals.

[0003] This document also describes methods performed by the systems summarized above and other configurations of radar systems set forth herein, as well as apparatuses for performing those methods.

[0004] This summary introduces simplified concepts related to enabling FDM techniques with polyphase shifters in radar systems, which are further described in the DETAILED DESCRIPTION and the accompanying drawings. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for determining the scope of the claimed subject matter. BRIEF DESCRIPTION OF DRAWINGS

[0005] Details of one or more aspects of slow-time frequency division multiplexing with polyphase shifters are described in this document with reference to the following drawings. Like numbers refer to like features throughout the drawings:

[0006] Figure 1 An example environment in which a radar system can use FDM with polyphase shifters is shown in accordance with the techniques of this disclosure;

[0007] Figure 2 An example configuration of a radar system using FDM with polyphase shifters within a vehicle is shown in accordance with the techniques of this disclosure;

[0008] Figure 3 , Figure 4-1 , Figure 4-2 , Figure 5-1 and Figure 5-2 An example conceptual diagram of a radar system using FDM with polyphase shifters is shown;

[0009] Figure 6 An example plot of transmitted EM signals using FDM with polyphase shifters is shown;

[0010] Figure 7 An example plot of received EM signals in Doppler bins for a radar system using FDM with polyphase shifters is shown;

[0011] Figure 8 An example method of a radar system using FDM with polyphase shifters to determine Doppler frequencies of objects is shown;

[0012] Figures 9-11 An example graphical representation of the association of channels and sectors in a radar system using FDM with polyphase shifters is shown; and

[0013] Figures 12-17 An example flowchart of a radar system using FDM with polyphase shifters to perform non-coherent integration and determine actual detections associated with objects is shown. DETAILED DESCRIPTION

[0014] SUMMARY

[0015] Radar systems can be configured as an important sensing technology that vehicle-based systems use to acquire information about the surrounding environment. For example, a vehicle-based system can use a radar system to detect objects in or near a roadway and take necessary actions (e.g., reduce speed, change lanes) to avoid a collision if necessary.

[0016] Radar systems often include at least two antennas to transmit and receive radar (e.g., EM) signals. Many vehicle-based systems require high resolution in range, Doppler frequency, and angle. These systems also require accurate discrimination of multiple targets with similar range or Doppler frequency. Design engineers often address these requirements by including more antenna channels in the radar system. For example, some automotive radar systems operate MIMO radar 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 of twelve channels (also referred to as a “synthetic array”). With the additional channels, the MIMO radar system can operate with improved angular resolution, which relies on a flexible physical layout that is less expensive and can have fewer hardware components than traditional non-MIMO radar systems.

[0017] MIMO radar systems often use orthogonal waveforms to transmit and receive independent, orthogonal EM signals and identify or separate different channels. Radar systems can implement orthogonal waveforms in various ways, including using time-division multiplexing (TDM), FDM, and code-multiplexing (CM) techniques. However, each orthogonal waveform technique has associated advantages and disadvantages.

[0018] For example, FDM techniques often place signals from transmit channels in different frequency bands by adding a frequency offset to the transmitted signal. Such techniques often operate in the fast-time (range) domain, introduce range-dependent phase offsets between channels, and reduce range coverage. FDM techniques can also require higher sampling rates due to the increased intermediate frequency bandwidth.

[0019] CM techniques can enable simultaneous transmission and operate in the fast-time domain (e.g., within a chirp, range domain) and the slow-time domain (e.g., chirp-to-chirp, Doppler domain). CM techniques often recover signals that match a current code by suppressing energy from other coded signals. The distributed EM energy left over from the suppressed signals is often considered a residual or noise and limits the dynamic range of the radar system. Smaller dynamic ranges limit the radar system’s ability to discriminate between smaller and larger objects.

[0020] Some TDM techniques do not support simultaneous transmission. Instead, individual transmitters transmit in sequence, resulting in less interference between transmit channels and enabling maximum orthogonality. However, such techniques often do not provide the signal-to-noise advantages enabled with simultaneous transmission (e.g., FDM and CM techniques) and can result in Doppler ambiguities between channels.

[0021] The previously used techniques, including those described above, generally do not provide sufficient discrimination between channels, resulting in a small signal-to-noise ratio. In contrast, this document describes techniques and systems for providing a radar system that uses FDM techniques with multi-phase shifters to enable simultaneous transmission. In this way, the described techniques and systems support multiple transmitters transmitting simultaneously with accurate recovery and without Doppler ambiguity. For example, a radar system of a vehicle includes multiple transmitters, multiple receivers, multiple multi-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 by one or more objects. The multi-phase shifters can introduce at least three potential phase shifts to the transmitted EM signals, the received EM signals, or both. The multi-phase shifters are operatively connected to the transmitters, the receivers, or a combination of both. The processor can control the multi-phase shifters to introduce the phase shifts. The processor can also divide a Doppler spectrum of the received EM signals into multiple sectors representing respective frequency ranges. Each channel is associated with a respective sector. The processor can determine potential detections of the objects using non-coherent integration of the received EM signals across the sectors. The processor can then determine actual detections. In this way, multiple transmitters are supported to transmit simultaneously with accurate recovery and without Doppler ambiguity. Accurate recovery is possible by avoiding interference between channels. The described FDM techniques avoid ambiguity by identifying each channel without additional information.

[0022] This example is merely one example of the described techniques and systems of a radar system that uses slow-time frequency division multiplexing with multi-phase shifters. This document describes other examples and implementations.

[0023] Operating Environment

[0024] Figure 1 An example environment 100 is shown in which a radar system 104 can use FDM with multi-phase shifters 116 in accordance with the techniques of this disclosure. In the depicted environment 100, the radar system 104 is mounted to or integrated within a vehicle 102 that is traveling on a road 106. Within a field of view 108, the radar system 104 can detect one or more objects 110 in a region near the vehicle 102.

[0025] The radar system 104 can detect one or more objects 110 in a vicinity of the vehicle 102. Although shown as a sedan, the vehicle 102 can represent other types of motorized vehicles (e.g., a coupe, a car, a truck, a motorcycle, a bus, a tractor, a semi-trailer), non-motorized vehicles (e.g., a bicycle), a rail vehicle (e.g., a train), a watercraft (e.g., a boat), an aircraft (e.g., an airplane), or a spacecraft (e.g., a satellite). In general, a manufacturer can install the radar system 104 to any mobile platform, including a mobile machine or robotic device.

[0026] In the depicted implementation, the radar system 104 is installed on a front of the vehicle 102 and illuminates the objects 110. The radar system 104 can detect the objects 110 from any exterior surface of the vehicle 102. For example, a vehicle manufacturer can integrate the radar system 104 into a bumper, a side mirror, a headlight, a taillight, or any other interior or exterior location where the objects 110 need to be detected. In some cases, the vehicle 102 includes multiple radar systems 104, such as a first radar system 104 and a second radar system 104 that provide a greater instrument field of view 108. In general, a vehicle manufacturer can design a location of the radar system 104 to provide a particular field of view 108 that encompasses a region of interest. Example fields of view 108 include a 360-degree field of view, one or more 180-degree fields of view, one or more 90-degree fields of view, and so on, which can overlap or be combined into a field of view 108 of a particular size.

[0027] The objects 110 are composed of one or more materials that reflect radar or EM signals. Depending on the application, the objects 110 can represent targets of interest. In some cases, the objects 110 can be moving objects (e.g., another vehicle) or stationary objects (e.g., a roadside sign, a road hazard, debris). Depending on the application, the objects 110 can represent targets of interest from which the vehicle 102 can safely navigate on the road 106.

[0028] The radar system 104 emits EM radiation by transmitting EM signals or waveforms via antenna elements. For example, in the environment 100, the radar system 104 can detect and track the objects 110 by transmitting and receiving one or more EM signals. For example, the radar system 104 can transmit EM signals between one hundred and four hundred gigahertz (GHz), between four and one hundred GHz, or between approximately seventy and eighty GHz.

[0029] The radar system 104 can be a MIMO radar system that can match reflected EM signals to corresponding objects 110. The radar system 104 can also operate as a traditional radar system that does not rely on MIMO technology. The radar system 104 can include a transmitter 112 for transmitting EM signals. The radar system 104 can also include a receiver 114 for receiving reflected versions of the EM signals. The transmitter 112 includes one or more components, including antennas or antenna elements, for transmitting EM signals. The receiver 114 includes one or more components, including antennas or antenna elements, for detecting reflected EM signals. The transmitter 112 and the receiver 114 can be incorporated together on the same integrated circuit (e.g., a transceiver integrated circuit) or separately on different integrated circuits. In other implementations, the radar system 104 does not include separate antennas, but the transmitter 112 and the receiver 114 each include one or more antenna elements.

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

[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 can 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 determine a location of the object 110 relative to the radar system 104 using a spectrum analysis module 122 and a non-coherent integrator 124. The processor 118 can also detect various characteristics of the object 110 (e.g., distance, target angle, rate of change of distance, velocity). The processor 118 can include instructions or be configured to control the transmitter 112, the receiver 114, and the multiphase shifter 116. The processor 118 can also generate radar data for at least one automotive system. For example, the processor 118 can control an autonomous or semi-autonomous driving system of the vehicle 102 based on processed EM energy from the receiver 114.

[0032] The spectral analysis module 122 allows for multiple channels in the received EM signal to resolve Doppler ambiguities among the received EM signals. Specifically, the spectral analysis module 122 can divide the Doppler spectrum of the received EM signal into a number of sectors. The sectors represent respective frequency ranges within the Doppler spectrum. For example, the spectral analysis module 122 can generate more sectors than the number of channels and make the size of the sectors equal. As another example, the spectral analysis module 122 can generate the same number of sectors as the number of channels and make the size of the sectors unequal (e.g., each sector has a different frequency width). As yet another example, the spectral analysis module 122 can generate the same number of sectors as the number of channels and determine the size of the sectors as having a subset of sectors of equal size and another subset of sectors of unequal size. The generation of sectors and the association of channels to sectors are described in more detail with reference to Figures 9 to 11 The generation of sectors and the association of channels to sectors are described in more detail with reference to

[0033] The non-coherent integrator 124 can process the EM energy received by the receivers 114 to identify the object 110 and resolve Doppler ambiguities related to the object 110 within the field of view 108 of the radar system 104. The non-coherent integrator 124 can use several schemes to reject aliased detections and resolve Doppler ambiguities. The schemes used by the non-coherent integrator 124 can include single channel detection and de-aliasing, circular shift and minimum analysis, sum and carrier knowledge, sector-based integration and maximum analysis, and circular shift and minimum and maximum analysis, as described in more detail with reference to Figures 12 to 17 The non-coherent integrator 124 can process the EM energy received by the receivers 114 to identify the object 110 and resolve Doppler ambiguities related to the object 110 within the field of view 108 of the radar system 104. The non-coherent integrator 124 can use several schemes to reject aliased detections and resolve Doppler ambiguities. The schemes used by the non-coherent integrator 124 can include single channel detection and de-aliasing, circular shift and minimum analysis, sum and carrier knowledge, sector-based integration and maximum analysis, and circular shift and minimum and maximum analysis, as described in more detail with reference to

[0034] The described radar system 104 can facilitate simultaneous transmission of multiple transmitter channels of a MIMO radar system with the multiple-phase shifter 116. The described aspects of FDM with the multiple-phase shifter support simultaneous transmission of multiple transmitters 112 with accurate recovery and without Doppler ambiguities. Accurate recovery is possible because interference among the channels is avoided using the spectral analysis module 122. Doppler ambiguities are resolved using the non-coherent integrator 124 to reject aliased detections.

[0035] As an example environment, Figure 1The vehicle 102 is shown traveling on a road 106. The radar system 104 detects an object 110 in front of the vehicle 102. The radar system 104 can define a coordinate system having an x-axis (e.g., in a 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, a z-axis (e.g., perpendicular to the x-y plane defined by the x-axis and the y-axis). The transmitter 112 of the radar system 104 can transmit EM signals in front of the vehicle 102. The object 110 can reflect the transmitted EM signals as reflected EM signals. The receiver 114 can detect the reflected EM signals.

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

[0037] In general, the automotive system uses the radar data provided by the radar system 104 to perform a function. For example, the driver-assistance system can provide blind spot monitoring and generate an alert indicating a potential collision with the object 110 detected by the radar system 104. In such implementations, the radar data from the radar system 104 indicates when it is safe or unsafe to change lanes. The autonomous driving system can move the vehicle 102 to a particular location on the road 106 while avoiding collisions with the object 110 detected by the radar system 104. The radar data provided by the radar system 104 can provide information about the distance to the object 110 and the location of the object 110 to enable the autonomous driving system to perform emergency braking, perform a lane change, or adjust the speed of the vehicle 102.

[0038] Figure 2 An example configuration of a radar system that uses FDM with a polyphase displacer within a vehicle 102 is shown in accordance with the techniques of this disclosure. The vehicle 102 can include a driving system 206, including an autonomous driving system 208 or a semi-autonomous driving system 210, that uses radar data from the radar system 104 to control the vehicle 102. As described with reference to Figure 1 The vehicle 102 can include the radar system 104, as described with reference to

[0039] The vehicle can also include one or more sensors 202, one or more communication devices 204, and a driving system 206. The sensors 202 can include a location sensor, a camera, a lidar system, or a combination thereof. For example, the location sensor can include a positioning system that can determine a location of the vehicle 102. The camera system can be mounted on the vehicle 102 or near the front of the vehicle 102. The camera system can take photographic images or video of the roadway 106. In other implementations, a portion of the camera system can be mounted into a rearview mirror of the vehicle 102 to have a field of view of the roadway 106. In yet other implementations, the camera system can project a field of view from any exterior surface of the vehicle 102. For example, the vehicle manufacturer can integrate at least a portion of the camera system into a side mirror, a bumper, a roof, or any other interior or exterior location where the field of view includes the roadway 106. The lidar system can use electromagnetic signals to detect objects 110 (e.g., other vehicles) on the roadway 106. Data from the lidar system can provide input to the spectral analysis module 122 or the non-coherent integrator 124. For example, the lidar system can determine a speed of travel of a vehicle ahead of the vehicle 102 or a nearby vehicle traveling in the same direction as the vehicle 102.

[0040] The communication devices 204 can be radio frequency (RF) transceivers for transmitting and receiving RF signals. The transceivers can include one or more transmitters and receivers that are incorporated together on the same integrated circuit (e.g., a transceiver integrated circuit) or separately on different integrated circuits. The communication devices 204 can be used to communicate with remote computing devices (e.g., servers or computing systems that provide navigation information or regional speed limit information), nearby structures (e.g., construction zone traffic signs, traffic lights, school zone traffic signs), or nearby vehicles. For example, the vehicle 102 can use the communication devices 204 to wirelessly exchange information with nearby vehicles using vehicle-to-vehicle (V2V) communication. The vehicle 102 can use the V2V communication to obtain the speed, location, and heading of nearby vehicles. Similarly, the vehicle 102 can use the communication devices 204 to wirelessly receive information from nearby traffic signs or structures that indicate temporary speed limits, traffic congestion, or other traffic-related information.

[0041] The communication devices 204 can include a sensor interface and a driving system interface. The sensor interface and the driving system interface can transfer data between the radar system 104 and the driving system 206 over a communication bus of the vehicle 102.

[0042] 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, that relies on data from the radar system 104 to control operation of the vehicle 102 (e.g., to set a driving speed or to avoid objects 110). Generally, the driving system 206 uses data provided by the radar system 104 (and, in particular, the non-coherent integrator 124) and / or the sensors 202 to control the vehicle 102 and perform certain functions. For example, the semi-autonomous driving system 210 can provide adaptive cruise control and dynamically adjust a travel speed of the vehicle 102 based on the presence of objects 110 ahead of the vehicle 102. In this example, data from the non-coherent integrator 124 can identify the objects 110 and their speed relative to the vehicle 102.

[0043] The autonomous driving system 208 can navigate the vehicle 102 to a particular destination while avoiding objects 110 identified by the non-coherent integrator 124 and / or the radar system 104. Data provided by the radar system 104 regarding the objects 110 can provide information about the location and / or speed of the objects 110 to enable the autonomous driving system 208 to adjust a speed of the vehicle 102.

[0044] Example Configuration

[0045] Figure 3 An example conceptual diagram 300 is shown that uses a radar system 302 that utilizes FDM with a polyphase displacer 308. For example, the radar system 302 can be the radar system 104 of Figure 1 and Figure 2 The conceptual diagram 300 illustrates components of the radar system 302 as distinct components, but some or all of them can be combined into a smaller subset of different components.

[0046] In the depicted implementation, the radar system 302 includes a plurality of transmitters 304, which are shown in this example as antenna elements, configured to transmit respective EM signals. The radar system 302 uses the transmitted EM signals to detect any objects 110 in a near-field region of the vehicle 102 within the field of view 108. In some implementations, the transmitters 304 can transmit a linear frequency modulated signal (e.g., a chirp signal). In other implementations, the transmitters 304 can transmit a phase-modulated continuous wave (PMC W) signal or a pulsed signal (e.g., an unmodulated signal). The transmitted EM signals can be any workable signal for a radar system. The radar system 302 also includes a plurality of receivers 306, which are shown in this example as antenna elements, configured to receive reflected EM signals reflected by the objects 110.

[0047] 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.

[0048] 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.

[0049] A multiphase shifter 308 can control the phase shift applied to or introduced into one or more EM signal pulses emitted by transmitter 304. Each multiphase shifter 308 has multiple potential output stages (e.g., 4, 8, 16, 32, or 64 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., 2-bit, 3-bit, 4-bit, 5-bit, or 6-bit), thus allowing the multiphase shifter 308 to have more than two phase stages. The increased number of potential phase stages provides greater flexibility in the FDM coding scheme applied by radar system 302 than that offered by binary phase shifters. The multiphase control signal 310 can add a progressive phase modulation φ to the emitted EM signal pulse, which shifts the frequency or Doppler frequency of the reflected EM signal by a frequency ω. c The offset frequency ω c Equals the product of 2, π, and phase modulation (e.g., ω). c =2πφ).

[0050] As described above, the receiver 306 receives the reflected EM signals. The radar system 302 processes the received EM signals to make one or more determinations related to the object 110 within the field of view 108 of the radar system 302. The receiver 306 is operatively coupled to a respective low noise amplifier (LNA) 314. The LNA 314 can amplify the received EM signals without significantly degrading the signal-to-noise ratio. The LNA 314 is operatively coupled to a respective mixer 316, which is coupled to the VCO 312. The output of the VCO 312 is used as a reference signal and combined with the respective received EM signal in the mixer 316. The radar system 302 passes the respective received EM signals through a bandpass filter (BPF) 318 and an analog-to-digital converter (ADC) 320 before analyzing them with a digital signal processor (DSP) 322. The DSP 322 can make one or more determinations related to the object 110, including resolving Doppler ambiguities. The BPF 318 can pass frequencies within a particular range in the received EM signals and reject or attenuate frequencies outside of the range. In other implementations, the radar system 302 can use additional or different filters, including a low-pass filter or a high-pass filter. The ADC 320 converts the analog EM signals to digital signals. The DSP 322 can use the non-coherent integrator 124 to resolve Doppler ambiguities and identify Doppler frequencies associated with the object 110. While the DSP 322 is shown as a component separate from the processor, the radar system 302 can include a single processor that controls the transmission of EM signals and makes determinations from the reception of EM signals.

[0051] Figure 4-1 and Figure 4-2 respectively. For example, the radar systems 402 and 412 can be radar systems 104 of Figure 1 and Figure 2 Conceptual diagrams 400 and 410 respectively illustrate components of the radar systems 402 and 412 as distinct components, but some or all of them can be combined into a smaller subset of different components.

[0052] The radar systems 402 and 412 include components similar to those described above for Figure 3The radar system 302 depicted in FIG. 3 includes components similar to those of the radar system 402 and 412. For example, the radar system 302 includes 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 the mixer 316 in the receiver path of the radar system 302. In Figure 4-1 the polyphase shifter 308 is operatively coupled to each receive channel, and then to a single downconversion or analog-to-digital conversion channel. In Figure 4-2 the polyphase shifter 308 is operatively coupled to each receive channel, and then to a single downconversion or analog-to-digital conversion channel. In

[0053] The polyphase shifter 308 can also be operatively coupled between other components in the receiver path, including between the receiver 306 and the LNA 314. The polyphase shifter 308 is not operatively coupled to the transmitter 304, but is associated with the receiver 306, respectively. The polyphase shifter 308 can introduce or apply a phase shift to the received EM signal. The radar system 402 or 412 can combine (e.g., superimpose) signals received by one or more of the receivers 306 prior to analog-to-digital conversion by the ADC 320.

[0054] As described above, each polyphase shifter 308 has a number of potential output stages (e.g., 4 stages, 8 stages, 16 stages, 32 stages, or 64 stages). For example, the processor 118 can provide a polyphase control signal 310 to the polyphase shifter 308 to control or set the phase stage of each polyphase shifter 308. The polyphase control signal 310 can be a multi-bit signal (e.g., 2 bits, 3 bits, 4 bits, 5 bits, or 6 bits), giving the polyphase shifter 308 more than two phase stages. The increased number of potential phase stages provides greater flexibility in the FDM encoding scheme applied by the radar system 402 or 502 to the received EM signal than is possible with a binary phase shifter. The polyphase control signal 310 can add a progressive phase modulation φ to the received EM signal pulse, which shifts the frequency or Doppler frequency of the reflected EM signal by an offset frequency ω c c ​equal to the product of two, pi, and the phase modulation (e.g., ω c = 2pif).

[0055] Figure 5-1 and Figure 5-2 Other example conceptual diagrams 500 and 510 of radar systems 502 and 512, respectively, using FDM with a multi-phase shifter 308 are shown. For example, the radar systems 502 and 512 can be radar systems 104 of Figure 1 and Figure 2 Conceptual diagrams 500 and 510 illustrate the components of the radar systems 502 and 512, respectively, as different components, but some or all of them can be combined into a smaller subset of different components.

[0056] The radar systems 502 and 512 include components similar to those depicted for the radar systems 302, 402, and 412 for Figure 3 , Figure 4-1 and Figure 4-2 The radar systems 502 and 512 include the transmitter 304, the receiver 306, the processor, the CRM, the multi-phase shifter 308, the VCO 312, the LNA 314, the mixer 316, the BPF 318, the ADC 320, and the DSP 322, for example. The multi-phase shifter 308 is operatively coupled to the transmitter 304 and the VCO 312 in the transmit path and to the LNA 314 and the mixer 316 in the receive path.

[0057] In Figure 5-1 , the multi-phase shifter 308 is operatively coupled to each receive channel, and then to a single downconversion or analog-to-digital conversion channel in the receive path. In Figure 5-2 , the multi-phase shifter 308 is operatively coupled to each receive channel, and a subset of the receive channels or the multi-phase shifters 308 are then operatively coupled to a downconversion or analog-to-digital conversion channel in the receive path. As shown in the conceptual diagram 510, the radar system 512 includes two multi-phase shifters 308 or receive channels for each downconversion or analog-to-digital conversion channel in the receive path. In other implementations, the radar system 512 can include another number of multi-phase shifters 308 or receive channels for each downconversion or analog-to-digital conversion channel in the receive path, resulting in N receive groups of M receive channels in the receive path.

[0058] In other implementations, the multi-phase shifter 308 can be operatively coupled to different components in the transmit path and the receive path. In the radar systems 502 and 512, the multi-phase shifter 308 is associated with both the transmitter 304 and the receiver 306, respectively. In the depicted implementations, the multi-phase shifter 308 can apply or introduce a phase shift to the transmitted EM signals and / or the received EM signals.

[0059] As described above, each multiphase shifter 308 has multiple potential output stages (e.g., 4, 8, 16, 32, or 64 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. Multiphase control signals 310 can be multi-bit signals (e.g., 2-bit, 3-bit, 4-bit, 5-bit, or 6-bit), allowing multiphase shifters 308 to have more than two phase stages. In the coding scheme applied by radar system 502 or 512 to the transmitted and / or received EM signals, the increased number of potential phase stages provides greater flexibility than that offered by binary phase shifters. Multiphase control signals 310 can add a progressive phase modulation φ to the transmitted and / or received EM signal pulses, which shifts the frequency or Doppler frequency of the reflected EM signal 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).

[0060] Figure 6 Figure 600 illustrates an example of an transmitted EM signal using an FDM employing a multiphase shifter. For example, Figure 600 shows a signal transmitted by... Figure 3 The EM signal may be transmitted by transmitter 304 of Figure 5. In other implementations, Figure 600 may show the EM signal received by receiver 306 of Figure 4 or Figure 5. As described above, in other implementations, transmitter 304 may transmit a linear frequency modulated signal (e.g., a chirped signal), a phase modulated continuous wave (PMCW) signal, or a pulse signal (e.g., an unmodulated signal).

[0061] Figure 600 illustrates an example strategy for controlling transmitter 304 and / or receiver 306. For example, the first transmitter in transmitter 304 transmits a first signal pulse 602 based on the operation of VCO 312. The first signal pulse 602 has a first phase, which in this example corresponds to zero degrees. The first phase can be considered as a fundamental phase or a reference phase.

[0062] The second transmitter in transmitter 304 transmits a second signal pulse 604 based on the operation of VCO 312 and the corresponding multiphase shifter 308. The second signal pulse 604 has a second phase that is phase-shifted by φ from the first signal pulse 602. As a result, the second phase is shifted from the first phase by a channel frequency ω equal to 2πφ. c .

[0063] A third one of the transmitters 304 transmits a third signal pulse 606 based on operation of the VCO 312 and the corresponding multiphase shifter 308. The third signal pulse 606 has a third phase that is phase shifted from the first signal pulse 602 by a phase shift of 2φ. As a result, the third phase is offset from the first phase by a channel frequency of 2ω c .

[0064] A fourth one of the transmitters 304 transmits a fourth signal pulse 608 based on operation of the VCO 312 and the corresponding multiphase shifter 308. The fourth signal pulse 608 has a fourth phase that is phase shifted from the first signal pulse 602 by a phase shift of 3φ. As a result, the fourth phase is offset from the first phase by a channel frequency of 3ω c .

[0065] A fifth one of the transmitters 304 transmits a fifth signal pulse 610 based on operation of the VCO 312 and the corresponding multiphase shifter 308. The fifth signal pulse 610 has a fifth phase that is phase shifted from the first signal pulse 602 by a phase shift of 4φ. As a result, the fifth phase is offset from the first phase by a channel frequency of 4ω c .

[0066] A sixth one of the transmitters 304 transmits a sixth signal pulse 612 based on operation of the VCO 312 and the corresponding multiphase shifter 308. The sixth signal pulse 612 has a sixth phase that is phase shifted from the first signal pulse 602 by a phase shift of 5φ. As a result, the sixth phase is offset from the first phase by a channel frequency of 5ω c .

[0067] Having the signal pulses transmitted simultaneously and including the phase shifts makes it possible to accurately recover the received EM signal information without having Doppler ambiguity. The MIMO feature also can reduce or eliminate signal-to-noise ratio loss. In other implementations, the radar system can use a hybrid of FDM and CM (e.g., code division multiplexing) schemes to apply the described phase shifts to the transmitted EM signals. The radar system also can use a pseudo-random outer code to apply the described phase shifts.

[0068] Figure 7 An example graph 700 of received EM signal in Doppler bins using a radar system that utilizes FDM with multiphase shifters is shown. The radar system can be the radar system 104 of Figure 1 and Figure 2 the radar system 302 of Figure 3 the radar system 402 of Figure 4-1 the radar system 412 of Figure 4-2 the radar system 502 of Figure 5-1 or the radar system 512 of Figure 5-2 .

[0069] The received EM signal corresponds to one of the signal pulses and includes a first peak 702. The first peak 702 has a first amplitude and is centered around a frequency-shifted signal 704, which depends on a Doppler frequency ω D 706 and a frequency shift ω c 708. As described with reference to Figure 6 , the frequency shift 708 is proportional to the phase shift introduced by the multi-phase shifter 308. The Doppler frequency 706 is related to the relative velocity difference between the object 110 and the radar system 104. In the described radar system 104, the received EM signal can include several peaks associated with a single object 110. With reference to Figures 8 to 17 The described techniques and systems enable the radar system 104 to identify the actual peak associated with the object 110 and resolve the Doppler ambiguity in the received EM signal.

[0070] An example method

[0071] Figure 8 An example method 800 of a radar system that determines a Doppler frequency of an object using FDM with a multi-phase shifter is shown. The method 800 is shown as a plurality of groups of operations (or acts) being performed, but is not necessarily limited to the order or combination of operations shown herein. Moreover, any of one or more of the operations can be repeated, combined, or reorganized to provide other methods. In the following discussion of the various sections, reference can be made to the environment 100 and the entities detailed in Figure 1 , and Figures 1 to 7 , which are referenced for example only. The techniques are not limited to being performed by one entity or multiple entities. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 , the radar system 302 of Figure 3 , the radar system 402 of Figure 4-1 , the radar system 412 of Figure 4-2 , the radar system 502 of Figure 5-1 , or the radar system 512 of Figure 5-2 , which determines a Doppler frequency of an object 110 around the vehicle 102.

[0072] At 802, EM signals are transmitted by a plurality of transmitters of a radar system in an FDM scheme. The radar system includes a first number of transmitters. For example, the transmitters 304 can transmit EM signals in an FDM scheme.

[0073] At 804, the EM signals reflected by the one or more objects are received by a plurality of receivers of the radar system. The radar system includes a second number of receivers. The received EM signals include a number of channels equal to a product of the number of transmitters (e.g., the first number) and the number of receivers (e.g., the second number). For example, the receivers 306 can receive the EM signals reflected by the object 110. The object 110 can reflect the EM signals transmitted by the transmitters 304. The received EM signals include a third number of channels equal to a product of the first number and the second number.

[0074] At 806, a plurality of multiphase shifters is controlled to introduce a phase shift to the transmitted EM signals and / or the received EM signals. The plurality of multiphase shifters is operatively connected to the plurality of transmitters and / or the plurality of receivers of the radar system. The phase shift includes one of at least three potential phase shifts. For example, the multiphase shifter 308 is operatively connected to the transmitters 304 and / or the receivers 306. The processor 118 can control the multiphase shifter 308 to introduce a phase shift to the transmitted EM signals and / or the received EM signals, where the phase shift includes one of at least three potential phase shifts. As described above, the processor 118 can use the multiphase control signal 310 to control the phase shifter 308. The multiphase control signal 310 can be a multi-bit signal (e.g., 2 bits, 3 bits, 4 bits, 5 bits, or 6 bits), allowing the multiphase shifter 308 to have more than two phase levels. The increased number of potential phase levels provides greater flexibility in the encoding scheme applied to the transmitted EM signals and / or the received EM signals than is possible with a binary phase shifter.

[0075] At 808, a Doppler spectrum of the received EM signals is divided into a fourth number of sectors. The sectors represent respective frequency ranges within the Doppler spectrum. The number of sectors can be equal to or greater than the number of channels (e.g., the third number). For example, the spectrum analysis module 122 can divide the Doppler spectrum of the received EM signals into sectors. The number and size of the sectors can be selected to avoid symmetric patterns among the channels of the received EM signals, as described in more detail with reference to Figures 9 to 11 The division of the Doppler spectrum into sectors is described in more detail.

[0076] At 810, each channel of the received EM signals is associated with a respective sector of the sectors. For example, the spectrum analysis module 122 can associate the channels of the received EM signals with respective sectors of the sectors. The association of the channels with respective sectors is described in more detail with reference to Figures 9 to 11 The association of the channels with respective sectors is described in more detail.

[0077] At 812, non-coherent integration is performed on the received EM signal using at least one channel of the received EM signal across a sector. For example, the non-coherent integrator 124 can perform non-coherent integration on the received EM signal across a sector of the Doppler spectrum. Reference is made to Figures 12 to 17 Non-coherent integration on the received EM signal is described in more detail.

[0078] At 814, potential detections of one or more objects are determined based on the non-coherent integration. The potential detections include one or more actual detections and one or more alias detections of the one or more objects. For example, the non-coherent integrator 124, the DSP 322, or the processor 118 can determine potential detections of the object 110 based on the non-coherent integration. Reference is made to Figures 12 to 17 Identification of the potential detections of the object 110 is described in more detail.

[0079] At 816, actual detections of one or more objects are determined based on the potential detections. For example, the non-coherent integrator 124, the DSP 322, or the processor 118 can determine actual detections of the object 110 based on the potential detections. Reference is made to Figures 12 to 17 Identification of the actual detections of the object 110 is described in more detail.

[0080] At 818, a Doppler frequency associated with each of the one or more objects is determined based on the actual detections. For example, the DSP 322 or the processor 118 can determine a Doppler frequency associated with the object 110 based on the actual detections. Reference is made to Figures 12 to 17 Identification of the potential detections of the object 110 is described in more detail.

[0081] Figure 9 An example graphical representation 900 of an association of channels and sectors in a radar system using FDM with a polyphase displacer is shown. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 the radar system 302 of Figure 3 the radar system 402 of Figure 4-1 the radar system 412 of Figure 4-2 the radar system 502 of Figure 5-1 or the radar system 512 of Figure 5-2 .

[0082] The graphical representation 900 shows energy of the received EM signal as the y-axis and a corresponding Doppler frequency of the received EM signal as the x-axis. The received EM signal includes N channels 902 that are represented by triangular peaks corresponding to actual or alias detections within each channel in Figure 9 .

[0083] The radar system 104 or the spectrum analysis module 122 divides the Doppler spectrum of the received EM signal into M sectors 904 of equal size. The sectors 904 represent a range of frequencies within the Doppler spectrum of the received EM signal. The radar system 104 or the spectrum analysis module 122 selects the number of sectors 904, M, to be at least one more than the number of channels 902, N (e.g., M > N + 1). In general, the number of sectors 904, M, is kept small enough to maintain separation between the channels 902 within the Doppler spectrum. Consider that the Doppler spectrum is divided into six sectors 904 (e.g., M equals six), and the spectrum analysis module 122 can assign a frequency range of π / 3 or sixty degrees to each sector.

[0084] The radar system 104 or the spectrum analysis module 122 associates or places the channels 902 in separate sectors, with one channel 902 per sector 904. Because the number of channels 902, N, is less than the number of sectors 904, M, there is one or more empty sectors 906 that do not have a corresponding channel. The empty sectors 906 can be placed in various locations within the Doppler spectrum, including between, before, or after the channels 902. The placement of the channels 902 and the empty sectors 906 is arranged to avoid forming a symmetric spectrum, which can lead to ambiguity in the detection of the objects 110.

[0085] The placement of the channels 902 among the sectors affects the non-coherent integration and de-aliasing logic used by the radar system 104 and / or the non-coherent integrator 124. For example, the radar system 104 or the non-coherent integrator 124 can perform non-coherent integration over a combination of N sectors 904 (e.g., to form N + M spectra). The radar system 104 can then form a final non-coherent integration spectrum by taking a maximum value of the N + M spectra at each frequency bin. The radar system 104 can then find the sector corresponding to each object from the combination with the maximum value.

[0086] As another example, the radar system 104 or the spectrum analysis module 122 can divide the Doppler spectrum into 2 M equal sectors 904, where the number of channels N is less than 2 M but greater than or equal to 2 M-1 (e.g., 2 M-1 ≤ N < 2 M ). The radar system 104 associates or places the channels 902 in separate sectors, with one channel 902 per sector 904 and with (2 M- N) empty sectors 906. The empty sectors 906 can be placed in various locations within the Doppler spectrum, including between, before, or after the channels 902. If the number of channels 902, N, is even, the channels 902 are placed asymmetrically between the sectors 904. The radar system 104 can perform a non-coherent integration (e.g., ) over the N consecutive sectors 904 to form a 2 M spectrum. As described in more detail with reference to Figure 15 and Figure 16 , the radar system 104 can then form a final non-coherent integration spectrum by taking a maximum of the 2 M spectra at each frequency bin. The radar system 104 can then find the sector corresponding to each object from the combination of maxima.

[0087] Figure 10 An example graphical representation 1000 of the association of channels and sectors in a radar system using FDM with a polyphase shift is shown. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 , the radar system 302 of Figure 3 , the radar system 402 of Figure 4-1 , the radar system 412 of Figure 4-2 , the radar system 502 of Figure 5-1 , or the radar system 512 of Figure 5-2 .

[0088] The graphical representation 1000 shows the energy of the received EM signal as the y-axis and the corresponding Doppler frequency of the received EM signal as the x-axis. The received EM signal includes N channels 1002, which are represented by triangular peaks corresponding to actual detections or aliasing detections within each channel. Figure 10

[0089] ​The radar system 104 or the spectrum analysis module 122 divides the received EM signal into M sectors 1004, which have non-uniform sizes 1006. The sectors 1004 represent frequency ranges within the Doppler spectrum of the received EM signal. The radar system 104 or the spectrum analysis module 122 selects the number of sectors 1004, M, to be equal to the number of channels 1002, N (e.g., M = N). Considering a division of the Doppler spectrum into six sectors 1004 (e.g., M equals 6), each sector 1004 will have a corresponding size 1006 that is different for each sector 1004 (e.g., D1≠ D2≠ D3≠ D4≠ D5≠ D6). The radar system 104 or the spectrum analysis module 122 associates or places the channels 1002 in separate sectors 1004, with one channel 1002 per sector 1004. Because each sector 1004 has a different size 1006, the channels 1002 are asymmetric and avoid Doppler ambiguity in the detection of the object 110.

[0090] Figure 11 An example graphical representation 1100 of the association of channels and sectors in a radar system using FDM with polyphase shifters is shown. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 the radar system 302 of Figure 3 the radar system 402 of Figure 4-1 the radar system 412 of Figure 4-2 the radar system 502 of Figure 5-1 or the radar system 512 of Figure 5-2 .

[0091] The graphical representation 1100 shows the energy of the received EM signal as the y-axis and the corresponding Doppler frequency of the received EM signal as the x-axis. The EM signal includes N channels 1102, which are represented in Figure 11 by triangular peaks corresponding to actual or aliased detections within each channel.

[0092] The radar system 104 or the spectrum analysis module 122 divides the received EM signals into M sectors 1104 having a combination of uniform and non-uniform sizes or spacings 1106. In other words, some subsets of the sectors 1104 have uniform sizes 1106 and one or more other subsets of the 1104 have different sizes 1106. The sectors 1104 represent frequency ranges within the Doppler spectrum of the EM signals. The radar system 104 or the spectrum analysis module 122 selects the number of sectors 1104 M to be equal to the number of channels 1102 N (e.g., M = N). Considering a division of the Doppler spectrum into six sectors 1104 (e.g., M equals six), the sectors 1104-1 and 1104-2 can have a first spacing Dl 1106-1, the sector 1104-3 can have a second spacing D2 1106-2, and the sectors 1104-4, 1104-5, and 1104-6 can have a third spacing D3 1106-3. The radar system 104 or the spectrum analysis module 122 associates or places the channels 1102 in the individual sectors with one channel 1102 per sector 1104. Due to the combination of uniform and non-uniform sizes 1006, the channels 1002 are asymmetric and avoid Doppler ambiguity in resolving the objects 110.

[0093] Figure 12 An example flowchart 1200 of a radar system that performs non-coherent integration and determines actual detections associated with objects using FDM with polyphase shifters is shown. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 the radar system 302 of Figure 3 the radar system 402 of Figure 4-1 the radar system 412 of Figure 4-2 the radar system 502 of Figure 5-1 or the radar system 512 of Figure 5-2 that determines actual detections of objects 110 around the vehicle 102.

[0094] At 1202, the radar system 104 receives EM energy. For example, the receiver 114 of the radar system 104 can receive EM energy reflected by the objects 110. The objects 110 can reflect EM energy emitted by the transmitter 112. The radar system 104 also divides the Doppler frequencies of the received EM energy into sectors and associates channels with the sectors, as described in more detail with reference to Figures 8 to 11 FIGURE 12A. The graphical plot 1210 shows potential detections 1212, 1214, and 1216 in a three-channel radar system. The graphical plot 1210 shows the relationship of the energy associated with the potential detections 1212, 1214, and 1216 to the corresponding Doppler frequencies.

[0095] At 1204, the radar system 104 generates a first logical list of potential detections for a first of the channels using a constant false alarm rate (CFAR) threshold. The CFAR threshold is used to detect an object reflection against a background of noise, clutter, and interference in a received EM signal of a single channel. In this manner, the CFAR threshold can be reduced or less than a typical CFAR threshold because a single one of the channels is being analyzed. For example, the radar system 104 can use a reduced CFAR to account for gain differences in the received EM signal of a single channel compared to incoherent integration gain from multiple channels.

[0096] The first logical list indicates potential detections within respective Doppler bins that include peaks of EM energy greater than the CFAR threshold. In other words, logical detections (e.g., logical detections 1220, 1222, and 1224) are identified by any energy peaks in the received EM signal that are greater than the reduced CFAR threshold. The logical list represents Doppler bins within the Doppler spectrum. The logical detection list 1218 shows a logical detection 1220 in a Doppler bin that corresponds to the center Doppler frequency of the potential detection 1212. Similarly, logical detections 1222 and 1224 correspond to the center Doppler frequencies of potential detections 1214 and 1216, respectively.

[0097] At 1206, the radar system 104 or the incoherent integrator 124 performs one or more circular shifts of the first logical list of potential detections based on the sector to generate additional logical lists. The number of circular shifts is equal to the number of channels N minus one (e.g., N-1). In the depicted implementation, two circular shifts are performed on the logical detection list 1218, resulting in logical detection lists 1226 and 1234. The logical detection list 1226 includes logical detections 1228, 1230, and 1232. The logical detection list 1234 includes logical detections 1236, 1238, and 1240.

[0098] At 1208, the radar system 104 or the incoherent integrator 124 uses a logical AND operator on the logical lists to determine or generate a final detection list of actual detections. For example, the radar system 104 or the incoherent integrator 124 determines actual detections of the object 110 by performing a logical AND operation on the logical detection lists 1218, 1226, and 1234 at each Doppler bin of the logical lists. As shown in the final detection list 1242, an actual detection 1244 is identified at a particular Doppler bin that corresponds to the logical detections 1224, 1232, and 1240. By using a single channel and its circular shifts, the radar system 104 can process radar data more quickly.

[0099] Figure 13Another example flow diagram 1300 is shown illustrating a radar system that performs non-coherent integration and determines actual detections associated with objects using FDM with polyphase shifters. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 the radar system 302 of Figure 3 the radar system 402 of Figure 4-1 the radar system 412 of Figure 4-2 the radar system 502 of Figure 5-1 or the radar system 512 of Figure 5-2 determines actual detections of objects 110 around the vehicle 102.

[0100] At 1302, the radar system 104 receives EM energy. For example, the receiver 114 of the radar system 104 can receive EM energy reflected by the objects 110. The objects 110 can reflect EM energy transmitted by the transmitter 112. The radar system 104 can generate a first EM spectrum of the received EM signal for a first of the channels. The radar system 104 also divides the Doppler frequencies of the received EM energy into sectors and associates the channels with the sectors, as described in more detail with reference to Figures 8 to 11 FIG. 13. The plot 1308 illustrates potential detections 1310, 1312, and 1314 in a three-channel radar system. The plot 1308 illustrates the relationship of the energy associated with the potential detections 1310, 1312, and 1314 to the corresponding Doppler frequencies.

[0101] At 1304, the radar system 104 performs one or more cyclic shifts on the first EM spectrum based on the sectors to generate additional EM spectra of the received EM signal. The number of cyclic shifts is equal to the number of channels N minus one (e.g., N-1). In the depicted implementation, two cyclic shifts are performed on the plot 1308, resulting in plots 1316 and 1318. The plots 1316 and 1318 illustrate the potential detections 1310, 1312, and 1314 at different center Doppler frequencies after the corresponding cyclic shifts. For example, the plot 1316 illustrates a cyclic shift of the plot 1308, and the plot 1318 illustrates a cyclic shift of the plot 1316.

[0102] At 1306, the radar system 104 determines a sum of EM energy levels at each Doppler bin of the EM spectrum across the first EM spectrum and the additional EM spectrum. For example, the radar system 104 can sum across the plot graphs 1308, 1316, and 1318 at each Doppler bin to generate a plot graph 1320. The plot graph 1320 includes potential detections 1322, 1328, 1330, 1332, 1334, and 1336. The potential detection 1322 includes a sum of EM energy associated with the potential detections 1310, 1312, and 1314. In this way, the actual location of the object 110 within the Doppler spectrum is fully integrated, resulting in a higher gain for the potential detection 1322. The aliased locations (e.g., potential detections 1328-1338) have a relatively smaller gain.

[0103] At 1308, the radar system 104 generates a logical list 1340 of potential detections (e.g., a logical detection list) using a CFAR threshold. The CFAR threshold is used to detect object reflections against a background of noise, clutter, and interference in the received EM signal of a single channel. The logical list 1340 indicates potential detections within a respective Doppler bin that include a peak of EM energy greater than the CFAR threshold. In other words, a logical detection (e.g., logical detections 1342, 1344, 1346, 1348, 1350, 1352, and 1354) is identified by any peak of energy in the received EM signal that is greater than the reduced CFAR threshold. The logical list represents Doppler bins within the Doppler spectrum. The logical detection list 1340 shows logical detections in Doppler bins that correspond to a center Doppler frequency of each potential detection.

[0104] At 1310, the radar system 104 determines actual detections of the object 110 by identifying aliased detections based on an association of each of the channels of the received EM signal with a respective sector. For example, the radar system 104 identifies an actual detection 1358 in a final detection list 1356. The radar system 104 can recursively select potential detections from the preliminary detections as actual final detections and identify potential aliased locations based on channel placement. The recursive process continues until a final detection is selected that identifies an appropriate number of aliased detections. By using a sum of cyclic shifts of single channel data, the radar system 104 generates a higher gain for the actual detections, making it easier to identify actual detections among noise, weak signals, and aliased detections.

[0105] Figure 14 Another example flowchart 1400 is shown of a radar system performing non-coherent integration and determining actual detections associated with an object using FDM with a polyphase shifter. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 the radar system 104 ofFigure 3 Radar system 302, Figure 4-1 Radar system 402, Figure 4-2 Radar system 412, Figure 5-1 Radar system 502 or Figure 5-2 The radar system 512 determines the Doppler velocity of an object 110 around the vehicle 102.

[0106] At 1402, radar system 104 receives EM energy. For example, receiver 114 of radar system 104 can receive EM energy reflected by object 110. Object 110 can reflect EM energy emitted by transmitter 112. Radar system 104 can generate a first EM spectrum of the received EM signal for a first channel in the channel. Radar system 104 also divides the Doppler frequencies of the received EM energy into sectors and associates channels with sectors, as shown in reference... Figures 8 to 11 A more detailed description is provided. Figure 1410 illustrates potential detectors 1412, 1414, and 1416 in a single channel of a three-channel radar system. Figure 1410 shows the relationship between the energy associated with potential detectors 1412, 1414, and 1416 and their corresponding Doppler frequencies.

[0107] At 1404, radar system 104 performs one or more cyclic shifts on the first EM spectrum based on sectors to generate an additional EM spectrum of the received EM signal. The number of cyclic shifts is equal to the number of channels N minus one (e.g., N–1). In the depicted implementation, two cyclic shifts are performed on graphic figure 1410, resulting in graphic figures 1418 and 1420. Graphic figures 1418 and 1420 illustrate potential detections 1412, 1414, and 1416 at different center Doppler frequencies after the corresponding cyclic shifts. For example, graphic figure 1418 illustrates the cyclic shifts of graphic figure 1410, and graphic figure 1420 illustrates the cyclic shifts of graphic figure 1418.

[0108] At 1406, radar system 104 determines the minimum EM energy level at each Doppler cell in the EM spectrum across the first EM spectrum and the additional EM spectrum. For example, radar system 104 may take the minimum at each Doppler cell across pattern diagrams 1410, 1418, and 1420 to generate pattern diagram 1422. Pattern diagram 1422 includes potential detection 1424. In this way, the actual location of object 110 within the Doppler spectrum is identified because aliasing detections at the same Doppler cells across each pattern diagram do not appear in each pattern diagram.

[0109] At 1408, radar system 104 generates a final detection list 1426 (e.g., a logical detection list) and determines the actual detection of object 110. The actual detection is determined by whether the minimum EM energy level at the corresponding Doppler chamber is greater than a CFAR threshold. The final detection list 1426 indicates which Doppler chambers identify the actual detection. Any energy peak in graphical representation 1422 that is greater than the CFAR threshold identifies the actual detection (e.g., actual detection 1428). The final detection list 1426 shows the logical detections in the Doppler chambers, which correspond to the center Doppler frequency of each potential detection.

[0110] Figure 15 Another example flowchart 1500 is shown, illustrating a radar system that uses FDM with multiphase shifters to perform incoherent integration and determine the actual detection associated with an object. 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, Figure 4-2 Radar system 412, Figure 5-1 Radar system 502 or Figure 5-2 The radar system 512 determines the Doppler velocity of an object 110 around the vehicle 102.

[0111] At 1502, radar system 104 receives EM energy. For example, receiver 114 of radar system 104 can receive EM energy reflected by object 110. Object 110 can reflect EM energy emitted by transmitter 112. Radar system 104 can generate a first EM spectrum of the received EM signal for a first channel in the channel. Radar system 104 also divides the Doppler frequency of the received EM energy into equal-sized sectors and associates channels with sectors, as shown in reference... Figure 9 A more detailed description is provided. Figure 1510 illustrates potential detectors 1520, 1522, and 1524 in a single channel of a three-channel radar system. Figure 1510 shows the relationship between the energy associated with potential detectors 1520, 1522, and 1524 and their corresponding Doppler frequencies.

[0112] At 1504, the radar system 104 or the non-coherent integrator 124 uses the first EM spectrum and determines, for each sector, a sector-based integration of EM energy. The radar system 104 or the non-coherent integrator 124 can perform a sector-based integration or summation of the EM energy received by a single channel. The number of sectors integrated together is equal to the number of channels N minus one (e.g., N-1). The number of sector-based integrations is equal to the number of channels N. In the depicted implementation, each sector-based integration includes three consecutive sectors. For example, for a potential target in sector 1512, the radar system 104 integrates the EM energy in sectors 1512, 1514, and 1516 together. For a potential target in sector 1514, the radar system 104 integrates the EM energy in sectors 1514, 1516, and 1518. For a potential target in sector 1514, the radar system 104 integrates the EM energy in sectors 1516, 1518, and 1512. And for a potential target in sector 1518, the radar system 104 integrates the EM energy in sectors 1518, 1512, and 1514.

[0113] The plot 1526 shows the results of the sector-based integrations, which include potential detections 1528, 1530, 1532, and 1534. In this way, the actual location of the object 110 within the Doppler spectrum gets a larger integration, resulting in a higher gain for the corresponding potential detection 1528. The aliased locations (e.g., potential detections 1530, 1532, and 1534) have a relatively smaller gain.

[0114] At 1506, the radar system 104 or the non-coherent integrator 124 determines the maximum EM energy level of the sector-based integrations of EM energy. For example, the radar system 104 can take the maximum values across the plot 1526 to generate a plot 1536. The plot 1536 includes the potential detection 1528. In this way, the actual location of the object 110 within the Doppler spectrum is identified, as the aliased detections do not get the same integration gain as the actual detection.

[0115] At 1508, the radar system 104 uses the CFAR threshold to generate a final detection list 1538 (e.g., a list of logical detections) to determine the actual detection. The final detection list 1538 indicates in which Doppler bin the actual detection is identified. The actual detection (e.g., actual detection 1540) is identified by any energy peak in the plot 1536 that is greater than the CFAR threshold. The final detection list 1538 shows the logical detection in the Doppler bin that corresponds to the center Doppler frequency of each potential detection.

[0116] Figure 16Another example flow diagram 1600 is shown for a radar system that performs non-coherent integration and determines actual detections associated with objects using FDM with polyphase shifters. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 the radar system 302 of Figure 3 the radar system 402 of Figure 4-1 the radar system 412 of Figure 4-2 the radar system 502 of Figure 5-1 or the radar system 512 of Figure 5-2 that determines Doppler velocities of objects 110 around the vehicle 102.

[0117] At 1602, the radar system 104 receives EM energy. For example, the receiver 114 of the radar system 104 can receive EM energy reflected by the objects 110. The objects 110 can reflect EM energy transmitted by the transmitter 112. The radar system 104 can generate a first EM spectrum of the received EM signal for a first of the channels. The radar system 104 also partitions Doppler frequencies of the received EM energy into sectors of equal size and associates the channels with the sectors, as described in more detail with reference to Figure 9 FIG. 16B. The plot 1612 shows potential detections 1614, 1616, and 1618 for a single channel in a three-channel radar system. The plot 1612 shows energy associated with the potential detections 1614, 1616, and 1618 versus corresponding Doppler frequencies.

[0118] At 1604, the radar system 104 or the non-coherent integrator 124 performs one or more cyclic shifts on the first EM spectrum based on the sectors to generate additional EM spectra of the received EM signal. The number of cyclic shifts is equal to the number of channels N minus one (e.g., N-1). In the depicted implementation, two cyclic shifts are performed on the plot 1612, resulting in plots 1620 and 1622. The plots 1620 and 1622 show the potential detections 1614, 1616, and 1618 at different center Doppler frequencies after the corresponding cyclic shifts. For example, the plot 1620 shows a cyclic shift of the plot 1612, and the plot 1622 shows a cyclic shift of the plot 1620.

[0119] At 1606, the radar system 104 or the non-coherent integrator 124 uses the first EM spectrum and the additional EM spectrum and determines, for each sector, a sector-based integration of EM energy. The sector-based integration represents a sum of EM energy of the respective sector across the first EM spectrum and the additional EM spectrum. For example, the radar system 104 can sum across the plot graphs 1612, 1620, and 1622 at each Doppler bin to generate a plot graph 1624. The plot graph 1624 includes potential detections 1626, 1628, 1630, and 1632. The potential detection 1626 includes a sum of EM energy associated with the potential detections 1614, 1616, and 1618. In this way, the actual location of the object 110 within the Doppler spectrum is fully integrated, resulting in a higher gain for the potential detection 1626. Aliased locations (e.g., the potential detections 1628, 1630, and 1632) have a relatively smaller gain.

[0120] At 1608, the radar system 104 or the non-coherent integrator 124 determines a maximum EM energy level of the sector-based integration of EM energy. For example, the radar system 104 can take a maximum across the plot graph 1624 to generate a plot graph 1634. The plot graph 1634 includes the potential detection 1626. In this way, the actual location of the object 110 within the Doppler spectrum is identified because aliased detections result in a lower sum gain.

[0121] At 1610, the radar system 104 generates a final detection list 1636 (e.g., a logical detection list) of actual detections. The final detection list 1636 indicates in which Doppler bins the actual detections 1638 are identified. The final detection list 1636 shows logical detections in Doppler bins that correspond to a center Doppler frequency of the actual detections 1638.

[0122] Figure 17 Another example flowchart 1700 is shown that illustrates a radar system that performs non-coherent integration and determines actual detections associated with objects using FDM with a polyphase displacer. For example, the radar system can be the radar system 104 of Figure 1 and Figure 2 the radar system 302 of Figure 3 the radar system 402 of Figure 4-1 the radar system 412 of Figure 4-2 the radar system 502 of Figure 5-1 or the radar system 512 of Figure 5-2 that determines Doppler velocities of objects 110 around the vehicle 102. The flowchart 1700 includes the same four operations as the flowchart 1600 (e.g., operations 1602, 1604, 1606, and 1608).

[0123] At 1602, the radar system 104 receives EM energy. For example, the receiver 114 of the radar system 104 can receive EM energy reflected by the object 110. The object 110 can reflect EM energy emitted by the transmitter 112. The radar system 104 can generate a first EM spectrum of the received EM signal for a first channel of the channels. The radar system 104 also partitions Doppler frequencies of the received EM energy into equal-sized sectors and associates the channels with the sectors, as described in reference to Figure 9 The plot 1612 illustrates potential detections 1614, 1616, and 1618 for a single channel in a three-channel radar system. The plot 1612 illustrates the relationship of energy associated with the potential detections 1614, 1616, and 1618 to corresponding Doppler frequencies.

[0124] At 1604, the radar system 104 or the non-coherent integrator 124 performs one or more cyclic shifts on the first EM spectrum based on the sectors to generate additional EM spectra of the received EM signal. The number of cyclic shifts is equal to the number of channels N minus one (e.g., N-1). In the depicted implementation, two cyclic shifts are performed on the plot 1612, resulting in plots 1620 and 1622. The plots 1620 and 1622 illustrate the potential detections 1614, 1616, and 1618 at different center Doppler frequencies after the corresponding cyclic shifts. For example, the plot 1620 illustrates a cyclic shift of the plot 1612, and the plot 1622 illustrates a cyclic shift of the plot 1620.

[0125] At 1606, the radar system 104 or the non-coherent integrator 124 determines a sector-based integration of EM energy for each sector using the first EM spectrum and the additional EM spectra. The sector-based integration represents a sum of EM energy of the respective sector across the first EM spectrum and the additional EM spectra. For example, the radar system 104 can sum across the plots 1612, 1620, and 1622 at each Doppler bin to generate a plot 1624. The plot 1624 includes potential detections 1626, 1628, 1630, and 1632. The potential detection 1626 includes a sum of EM energy associated with the potential detections 1614, 1616, and 1618. In this way, the actual location of the object 110 within the Doppler spectrum is fully integrated, resulting in a higher gain for the potential detection 1626. Aliased locations (e.g., the potential detections 1628, 1630, and 1632) have a relatively smaller gain.

[0126] At 1608, the radar system 104 or the non-coherent integrator 124 determines a maximum EM energy level of the sector-based integration of EM energy. For example, the radar system 104 can take a maximum across the plot graph 1624 to generate a plot graph 1634. The plot graph 1634 includes a potential detection 1626. In this way, the actual location of the object 110 within the Doppler spectrum is identified because the aliased detections result in a lower sum gain.

[0127] At 1702, the radar system 104 or the non-coherent integrator 124 determines a minimum EM energy level at each Doppler bin of the EM spectrum. For example, the radar system 104 or the non-coherent integrator 124 can take a minimum across the plot graphs 1612, 1620, and 1622 at each Doppler bin to generate a plot graph 1708. The plot graph 1708 includes a potential detection 1710. In this way, the actual location of the object 110 within the Doppler spectrum is identified because the aliased detections do not appear in each plot graph at the same Doppler bin across each plot graph.

[0128] At 1704, the radar system 104 or the non-coherent integrator 124 generates a preliminary minimum value detection list 1712 and a preliminary maximum value detection list 1716 using a CFAR threshold. The preliminary minimum value detection list 1712 includes a potential detection 1714. The preliminary maximum value detection list 1716 includes a potential detection 1718. The CFAR threshold is used to detect object reflections against a background of noise, clutter, and interference in a received EM signal of a single channel. The preliminary minimum value detection list 1712 indicates potential detections within a respective Doppler bin of the plot graph 1708 that include peaks having EM energy greater than the CFAR threshold. The preliminary maximum value detection list 1716 indicates potential detections within a respective Doppler bin of the plot graph 1708 that include peaks having EM energy greater than the CFAR threshold.

[0129] At 1706, the radar system 104 uses a logical AND operator on the preliminary minimum value detection list 1712 and the preliminary maximum value detection list 1716 at each Doppler bin to generate a final detection list 1720 of actual detections. The final detection list 1720 indicates which Doppler bins have actual detections 1722 identified. The final detection list 1720 shows logical detections in Doppler bins that correspond to a center Doppler frequency of the actual detections 1722.

[0130] Examples

[0131] In the following sections, examples are provided.

[0132] 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 operably connected to the plurality of transmitters, the plurality of receivers, or a combination thereof, the plurality of polyphase shifters configured to introduce at least three potential phase shifts; and a processor configured to control the plurality of polyphase shifters to introduce phase shifts to at least one of the transmitted EM signals or the received EM signals.

[0133] Example 2: The radar system of example 1, wherein: the plurality of transmitters comprises a first number of transmitters; the plurality of receivers comprises a second number of receivers, the second number equal to or not equal to the first number; the plurality of polyphase shifters comprises a third number of polyphase shifters, the third number equal to the first number, the second number, or a sum of the first number and the second number; and the received EM signals comprise a fourth number of channels, the fourth number equal to a product of the first number and the second number.

[0134] Example 3: The radar system of example 2, wherein: the plurality of polyphase shifters is operably connected to the plurality of transmitters; and the third number is equal to the first number.

[0135] Example 4: The radar system of example 2, wherein: the plurality of polyphase shifters is operably connected to the plurality of receivers; and the third number is equal to the second number.

[0136] Example 5: The radar system of example 2, wherein: the plurality of polyphase shifters is operably connected to the plurality of transmitters and the plurality of receivers; and the third number is equal to a sum of the first number and the second number.

[0137] Example 6: The radar system of example 2, wherein the processor is further configured to: divide a Doppler spectrum of the received EM signals into a fifth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum and being equal in size within the Doppler spectrum, the fifth number equal to or greater than the fourth number plus one; and associate each of the channels of the received EM signals with a respective one of the sectors, at least one of the sectors not being associated with a channel of the received EM signals, the association of the channels with the sectors configured to form an asymmetric spectrum.

[0138] Example 7: The radar system of Example 2, wherein the processor is further configured to: divide the Doppler spectrum of the received EM signal into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum and being non-equal in size within the Doppler spectrum; and associate each of the channels of the received EM signal with a respective one of the sectors, the association of the channels with the non-equal sectors configured to form an asymmetric spectrum.

[0139] Example 8: The radar system of Example 2, wherein the processor is further configured to: divide the Doppler spectrum of the received EM signal into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum, a subset of the sectors being equal in size within the Doppler spectrum and another subset of the sectors being non-equal in size within the Doppler spectrum; and associate each of the channels of the received EM signal with a respective one of the sectors, the association of the channels with the sectors configured to form an asymmetric spectrum.

[0140] Example 9: The radar system of any preceding example, wherein the processor is further configured to: control the plurality of polyphase shifters to dynamically adjust the phase shift introduced to at least one of the transmitted EM signal or the received EM signal.

[0141] Example 10: The radar system of any preceding example, wherein the plurality of transmitters and the plurality of receivers are configured to operate as part of a multiple-input and multiple-output (MIMO) radar method.

[0142] Example 11: The radar system of any preceding example, wherein the radar system is configured to be installed on an automobile.

[0143] Example 12: A computer-readable storage medium comprising computer- executable instructions that, when executed, cause a processor of a radar system to: transmit electromagnetic (EM) signals via a plurality of transmitters of the radar system in a frequency-division multiplexing (FDM) scheme; receive the EM signals reflected by one or more objects via a plurality of receivers of the radar system; and control a plurality of polyphase shifters to introduce a phase shift to at least one of the transmitted EM signals or the received EM signals, the plurality of polyphase shifters being operably connected to the plurality of transmitters, the plurality of receivers, or a combination thereof, the introduced phase shift comprising one of at least three potential phase shifts.

[0144] Example 13: The computer-readable storage medium of example 12, wherein: the plurality of transmitters comprises a first number of transmitters; the plurality of receivers comprises a second number of receivers, the second number being equal to or different than the first number; the plurality of polyphase shifters comprises a third number of polyphase shifters, the third number being equal to the first number, the second number, or a sum of the first number and the second number; and the received EM signal comprises a fourth number of channels.

[0145] Example 14: The computer-readable storage medium of example 13, wherein: the plurality of polyphase shifters is operatively connected to the plurality of transmitters; and the third number is equal to the first number.

[0146] Example 15: The computer-readable storage medium of example 13, wherein: the plurality of polyphase shifters is operatively connected to the plurality of receivers; and the third number is equal to the second number.

[0147] Example 16: The computer-readable storage medium of example 13, wherein: the plurality of polyphase shifters is operatively connected to the plurality of transmitters and the plurality of receivers; and the third number is equal to a sum of the first number and the second number.

[0148] Example 17: The computer-readable storage medium of example 13, wherein the instructions, when executed, further cause the processor of the radar system to: divide a Doppler spectrum of the received EM signal into a fifth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum and being equal in size within the Doppler spectrum, the fifth number being equal to or greater than the fourth number plus one; and associate each of the channels of the received EM signal with a respective one of the sectors, at least one of the sectors being unassociated with a channel of the received EM signal, the association of the channels with the sectors being configured to form the asymmetric spectrum.

[0149] Example 18: The computer-readable storage medium of example 13, wherein the instructions, when executed, further cause the processor of the radar system to: divide a Doppler spectrum of the received EM signal into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum and being unequal in size within the Doppler spectrum; and associate each of the channels of the received EM signal with a respective one of the sectors, the association of the channels with the unequal sectors being configured to form the asymmetric spectrum.

[0150] Example 19: The computer-readable storage medium of example 13, wherein the instructions, when executed, further cause the processor of the radar system to: divide a Doppler spectrum of the received EM signal into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum, a subset of the sectors being equal in size within the Doppler spectrum and another subset of the sectors being unequal in size within the Doppler spectrum; and associate each of the channels of the received EM signal with a respective one of the sectors, at least one of the sectors being unassociated with a channel of the received EM signal, the association of the channels with the sectors being configured to form an asymmetric spectrum.

[0151] Example 20: A method comprising: transmitting electromagnetic (EM) signals via a plurality of transmitters of a radar system in a frequency-division multiplexing (FDM) scheme; receiving the EM signals reflected by one or more objects via a plurality of receivers of the radar system; and controlling a plurality of polyphase shifters operably connected to the plurality of transmitters, the plurality of receivers, or a combination thereof, to introduce phase shifts into at least one of the transmitted EM signals or the received EM signals, the introduced phase shifts comprising one of at least three potential phase shifts.

[0152] Example 21 : A radar system comprising: a first number of receivers configured to receive 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 different from the first number, the received EM signals comprising a third number of channels, the third number being equal to a product of the first number and the second number, at least one of the transmitted EM signals or the received EM signals comprising inter-channel phase shifts; and a processor configured to: divide a Doppler spectrum of the received EM signal into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum, the fourth number being equal to or greater than the third number; associate each channel of the received EM signal with a respective one of the sectors; perform non-coherent integration of the received EM signal across the sectors using at least one channel of the received EM signal; determine potential detections of the one or more objects based on the non-coherent integration, the potential detections comprising one or more actual detections and one or more aliased detections of the one or more objects; determine actual detections of the one or more objects based on the potential detections; and determine a Doppler frequency associated with each of the one or more objects based on the actual detections.

[0153] Example 22: The radar system of example 21, wherein: the phase shifts are introduced by a first number of polyphase shifters operably connected to the receivers.

[0154] Example 23: The radar system of example 21, wherein: the phase shifts are introduced by a second number of polyphase shifters operably connected to the transmitters.

[0155] Example 24: The radar system of example 21, wherein: the phase shifts are introduced by a polyphase shifter operably connected to the receivers and the transmitters.

[0156] Example 25: The radar system of any of examples 21-24, wherein: the sectors are equal in size within the Doppler spectrum; the fourth number is equal to or greater than the third number plus one; and each of the channels of the received EM signals is associated with a respective one of the sectors, at least one of the sectors is not associated with a channel of the received EM signals, and the association of the channels with the sectors is configured to form the asymmetric spectrum.

[0157] Example 26: The radar system of any of examples 21-24, wherein: the sectors are unequal in size within the Doppler spectrum; the fourth number is equal to the third number; and each of the channels of the received EM signals is associated with a respective one of the sectors, the association of the channels with the unequal sectors is configured to form the asymmetric spectrum.

[0158] Example 27: The radar system of any of examples 21-24, wherein: a subset of the sectors are equal in size within the Doppler spectrum and another subset of the sectors are unequal in size within the Doppler spectrum; the fourth number is equal to the third number; and each of the channels of the received EM signals is associated with a respective one of the sectors, the association of the channels with the sectors is configured to form the asymmetric spectrum.

[0159] Example 28: The radar system of any of examples 21-27, wherein the processor is further configured to: determine potential detections of the one or more objects by: generating a first logical list of potential detections for a first one of the third number of channels using a constant false alarm rate (CFAR) threshold, the potential detections comprising one or more peaks within the received EM signals having EM energy greater than the CFAR threshold, the first logical list representing Doppler bins within the Doppler spectrum; and based on the sectors, performing a particular number of circular shifts on the first logical list of potential detections to generate a particular number of additional logical lists of potential detections, the particular number being equal to the third number minus one; and determining actual detections of the one or more objects by performing a logical AND operation on the first logical list of potential detections and the additional logical lists of potential detections at each Doppler bin of the logical lists.

[0160] Example 29: The radar system of any of Examples 21-27, wherein the processor is further configured to: determine potential detections of the one or more objects by: generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; performing a particular number of cyclic shifts on the first EM spectrum based on the sectors to generate a particular number of additional EM spectra of the received EM signal, the particular number equaling the third number minus one; and determining a minimum EM energy level at each Doppler bin of the EM spectra across the first EM spectrum and the additional EM spectra; and determine actual detections of the one or more objects by determining whether the minimum EM energy level at the respective Doppler bin is greater than a constant false alarm rate (CFAR) threshold.

[0161] Example 30: The radar system of any of Examples 21-27, wherein the processor is further configured to: determine potential detections of the one or more objects by: generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; performing a particular number of cyclic shifts on the first EM spectrum based on the sectors to generate a particular number of additional EM spectra of the received EM signal, the particular number equaling the third number minus one; determining a sum of EM energy levels at each Doppler bin of the EM spectra across the first EM spectrum and the additional EM spectra; and generating a logical list of potential detections using a constant false alarm rate (CFAR) threshold, the potential detections including one or more peaks within the sum of EM energy levels having EM energy greater than the CFAR threshold, the logical list representing Doppler bins within the Doppler spectrum; and determine actual detections of the one or more objects by identifying one or more aliased detections based on an association of each of the channels of the received EM signal with a respective one of the sectors.

[0162] Example 31 : The radar system of Example 25, wherein the processor is further configured to: determine potential detections of the one or more objects by: generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; and using the first EM spectrum and for each sector of a fourth number of sectors, determining a sector-based integration of EM energy, the sector-based integration summing EM energy of the respective sector with EM energy of a particular number of consecutive sectors, the particular number equaling the third number minus one; and determine actual detections of the one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

[0163] Example 32: The radar system of Example 25, wherein the processor is further configured to determine the potential detections of the one or more objects by: generating a first EM spectrum of the received EM signals for a first channel of the third number of channels; performing a certain number of cyclic shifts on the first EM spectrum based on the sectors to generate a certain number of additional EM spectra of the received EM signals, the certain number equaling the third number minus one; and using the first EM spectrum and the additional EM spectra and for each sector of a fourth number of sectors, determining a sector-based integration of EM energy, the sector-based integration summing EM energy for the respective sector across the first EM spectrum and the additional EM spectra; and determining the actual detections of the one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

[0164] Example 33: The radar system of Example 25, wherein the processor is further configured to determine the potential detections of the one or more objects by: generating a first EM spectrum of the received EM signals for a first channel of the third number of channels; performing a certain number of cyclic shifts on the first EM spectrum based on the sectors to generate a certain number of additional EM spectra of the received EM signals, the certain number equaling the third number minus one; using the first EM spectrum and the additional EM spectra and for each sector of a fourth number of sectors, determining a sector-based integration of EM energy, the sector-based integration summing EM energy for the respective sector across the first EM spectrum and the additional EM spectra; determining a minimum EM energy level at each Doppler bin of the EM spectrum across the first EM spectrum and the additional EM spectra; generating a first logical list of potential detections using a constant false alarm rate (CFAR) threshold and the sector-based integration of EM energy, the first logical list representing Doppler bins within the Doppler spectrum; and generating a second logical list of potential detections using the CFAR threshold and the minimum EM energy level at each Doppler bin of the EM spectrum; and determining the actual detections of the one or more objects by performing a logical AND operation on the first logical list and the second logical list of potential detections at each Doppler bin.

[0165] Example 34: The radar system of any one of Examples 21 to 33, wherein the transmitter and the receiver operate as part of a multiple-input and multiple-output (MIMO) radar method.

[0166] Example 35: The radar system of any one of Examples 21 to 34, wherein the radar system is configured to be installed on an automobile.

[0167] Example 36: A computer-readable storage medium comprising computer- executable instructions that, when executed, cause a processor of a radar system to: receive, via a first number of receivers, EM signals reflected by one or more objects, the EM signals transmitted by a second number of transmitters in a frequency-division multiplexing (FDM) scheme, the second number equal to or different than the first number, the received EM signals comprising a third number of channels, the third number equal to a product of the first number and the second number, at least one of the transmitted EM signals or the received EM signals comprising an inter-channel phase shift; divide a Doppler spectrum of the received EM signals into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum, the fourth number equal to or greater than the third number; associate each channel of the received EM signals with a respective sector of the sectors; perform, using at least one channel of the received EM signals, a non-coherent integration of the received EM signals across the sectors; determine, based on the non-coherent integration, potential detections of the one or more objects, the potential detections comprising one or more actual detections of the one or more objects and one or more aliased detections; determine, based on the potential detections, actual detections of the one or more objects; and determine, based on the actual detections, a Doppler frequency associated with each of the one or more objects.

[0168] Example 37: The computer-readable storage medium of Example 36, wherein: the sectors are equal in size within the Doppler spectrum; the fourth number is equal to or greater than the third number plus one; each of the channels of the received EM signals is associated with a respective sector of the sectors, at least one of the sectors is not associated with a channel of the received EM signals, the association of the channels with the sectors configured to form an asymmetric spectrum. And the computer-readable storage medium comprises computer-executable instructions that, when executed, further cause the processor of the radar system to: determine the potential detections of the one or more objects by: generating, for a first channel of the third number of channels, a first EM spectrum of the received EM signals; and using the first EM spectrum and for each sector of the fourth number of sectors, determining a sector-based integration of EM energy, the sector-based integration summing EM energy of the respective sector with EM energy of a particular number of consecutive sectors, the particular number equal to the third number minus one; and determine the actual detections of the one or more objects by determining a maximum EM energy level of the sector-based integrations of EM energy.

[0169] Example 38: The computer-readable storage medium of Example 36, wherein: the sectors are equal in size across the Doppler spectrum; the fourth number is equal to or greater than the third number plus one; each of the channels of the received EM signal is associated with a respective one of the sectors, at least one of the sectors is not associated with a channel of the received EM signal, the association of the channels with the sectors is configured to form an asymmetric spectrum. And the computer-readable storage medium comprises computer-executable instructions that, when executed, further cause the processor of the radar system to: determine a potential detection of one or more objects by: generating a first EM spectrum of the received EM signal for a first one of the third number of channels; performing a particular number of cyclic shifts on the first EM spectrum to generate a particular number of additional EM spectra of the received EM signal based on the sectors, the particular number being equal to the third number minus one; and determining, using the first EM spectrum and the additional EM spectra and for each of the fourth number of sectors, a sector-based integration of EM energy, the sector-based integration summing EM energy for the respective sector across the first EM spectrum and the additional EM spectra; and determine an actual detection of one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

[0170] Example 39: The computer-readable storage medium of Example 36, wherein: the sectors are equal in size across the Doppler spectrum; the fourth number is equal to or greater than the third number plus one; each of the channels of the received EM signal is associated with a respective one of the sectors, at least one of the sectors is not associated with a channel of the received EM signal, the association of the channels with the sectors is configured to form an asymmetric spectrum. And the computer-readable storage medium includes computer-executable instructions that, when executed, further cause the processor of the radar system to: determine potential detections of one or more objects by: generating a first EM spectrum of the received EM signal for a first one of the third number of channels; performing a particular number of cyclic shifts on the first EM spectrum to generate a particular number of additional EM spectra of the received EM signal based on the sectors, the particular number being equal to the third number minus one; determining, using the first EM spectrum and the additional EM spectra and for each of the fourth number of sectors, a sector-based integration of EM energy, the sector-based integration summing EM energy for the respective sector across the first EM spectrum and the additional EM spectra; determining a minimum EM energy level at each Doppler bin of the EM spectrum across the first EM spectrum and the additional EM spectra; generating a first logical list of potential detections using a constant false alarm rate (CFAR) threshold and the sector-based integration of EM energy, the first logical list representing Doppler bins within the Doppler spectrum; and generating a second logical list of potential detections using the CFAR threshold and the minimum EM energy level at each Doppler bin of the EM spectrum; and determining actual detections of one or more objects by performing a logical AND operation on the first logical list and the second logical list of potential detections at each Doppler bin.

[0171] Example 40: A method comprising: receiving, via a first number of receivers, 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 different from the first number, the received EM signals comprising a third number of channels, the third number being equal to a product of the first number and the second number, at least one of the transmitted EM signals or the received EM signals comprising an inter-channel phase shift; dividing a Doppler spectrum of the received EM signals into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum, the fourth number being equal to or greater than the third number; associating each channel of the received EM signals with a respective sector of the sectors; performing, using at least one channel of the received EM signals, a non-coherent integration of the received EM signals across the sectors; determining, based on the non-coherent integration, potential detections of the one or more objects, the potential detections comprising one or more actual detections of the one or more objects and one or more aliased detections; determining, based on the potential detections, actual detections of the one or more objects; and determining, based on the actual detections, a Doppler frequency associated with each of the one or more objects.

[0172] CONCLUSION

[0173] While various embodiments of the present disclosure have been described and illustrated in the foregoing description, it is understood that the present disclosure is not limited to the embodiments described and illustrated herein but can be embodied in various ways within the scope of the following claims. It will be apparent from the foregoing description that various changes can be made without departing from the scope of the present disclosure defined by the following claims.

Claims

1. A radar system comprising: a first number of receivers configured to receive EM signals reflected by one or more objects, the EM signals transmitted by a second number of transmitters in a frequency-division multiplexing (FDM) scheme, the second number equal to or not equal to the first number, the received EM signals comprising a third number of channels, the third number equal to a product of the first number and the second number, at least one of the transmitted EM signals or the received EM signals comprising a phase shift between the channels; and a processor configured to: divide a Doppler spectrum of the received EM signals into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum, wherein: the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; or the sectors are unequal in size within the Doppler spectrum and the fourth number is equal to the third number; or a subset of the sectors are equal in size within the Doppler spectrum and another subset of the sectors are unequal in size within the Doppler spectrum; and the fourth number is equal to the third number; associate each channel of the received EM signals with a respective one of the sectors to form an asymmetric spectrum, wherein if the fourth number of sectors is greater than the third number of channels, at least one of the sectors is not associated with a channel of the received EM signals; perform a non-coherent integration of the received EM signals across the sectors using at least one channel of the received EM signals; determine potential detections of the one or more objects based on the non-coherent integration, the potential detections comprising one or more actual detections and one or more aliased detections of the one or more objects; determine the actual detections of the one or more objects based on the potential detections; and determine a Doppler frequency associated with each of the one or more objects based on the actual detections.

2. The radar system of claim 1, wherein: the phase shift is introduced by a plurality of phase shifters operably connected to the first number of receivers.

3. The radar system of claim 1, wherein: the phase shift is introduced by a plurality of phase shifters operably connected to the second number of transmitters.

4. The radar system of claim 1, wherein: the phase shift is introduced by a plurality of phase shifters operably connected to the receivers and the transmitters.

5. The radar system of claim 1, wherein, the processor is further configured to: determine the potential detections of the one or more objects by: generating a first logical list of potential detections for a first channel of the third number of channels using a constant false alarm rate (CFAR) threshold, the potential detections comprising one or more peaks within the received EM signals having EM energy greater than the CFAR threshold, the first logical list representing a number of Doppler bins within the Doppler spectrum; and generating a second logical list of potential detections for a second channel of the third number of channels using a second CFAR threshold, the potential detections comprising one or more peaks within the received EM signals having EM energy greater than the second CFAR threshold, the second logical list representing a number of Doppler bins within the Doppler spectrum; and determining the potential detections of the one or more objects based on the first logical list and the second logical list. performing a certain number of circular shifts on the first logical list of potential detections based on the sector to generate the certain number of additional logical lists of potential detections, the certain number equal to the third number minus one; and determining the actual detections of the one or more objects by performing a logical AND operation on the first and additional logical lists of potential detections at each Doppler bin of the logical list.

6. The radar system of claim 1, wherein, The processor is further configured to: determine the potential detections of the one or more objects by: generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; performing a certain number of circular shifts on the first EM spectrum based on the sector to generate the certain number of additional EM spectra of the received EM signal, the certain number equal to the third number minus one; and determining the actual detections of the one or more objects by determining whether the minimum EM energy level at a corresponding Doppler bin is greater than a constant false alarm rate (CFAR) threshold. The processor is further configured to: determine the potential detections of the one or more objects by:

7. The radar system of claim 1, wherein, generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; performing a certain number of circular shifts on the first EM spectrum based on the sector to generate the certain number of additional EM spectra of the received EM signal, the certain number equal to the third number minus one; determining the sum of the EM energy levels at each Doppler bin of the EM spectra across the first and additional EM spectra; and generating a logical list of potential detections including one or more peaks having EM energy greater than a constant false alarm rate (CFAR) threshold within the sum of the EM energy levels, the logical list representing a number of Doppler bins within the Doppler spectrum; and determining the actual detections of the one or more objects by identifying the one or more aliased detections based on the association of each of the channels of the received EM signal with the respective one of the sectors. The sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one and the processor is further configured to: determine the potential detections of the one or more objects by:

8. The radar system of claim 1, wherein, generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; and ​ ​ determining, using the first EM spectrum and for each sector of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector with a certain number of consecutive sectors of the EM energy, the certain number equal to the third number minus one; and determining the actual detection of the one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

9. The radar system of claim 1, wherein, the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one and the processor is further configured to: determine the potential detection of the one or more objects by: generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; performing a certain number of cyclic shifts of the first EM spectrum based on the sectors to generate the certain number of additional EM spectra of the received EM signal, the certain number equal to the third number minus one; and determining, using the first EM spectrum and additional EM spectra and for each sector of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector across the first EM spectrum and additional EM spectra; and determining the actual detection of the one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

10. The radar system of claim 1, wherein, the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one and the processor is further configured to: determine the potential detection of the one or more objects by: generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; performing a certain number of cyclic shifts of the first EM spectrum based on the sectors to generate the certain number of additional EM spectra of the received EM signal, the certain number equal to the third number minus one; determining, using the first EM spectrum and additional EM spectra and for each sector of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector across the first EM spectrum and additional EM spectra; determining a minimum EM energy level at each Doppler bin of the EM spectrum across the first EM spectrum and additional EM spectra; generating a first logical list of potential detections using a constant false alarm rate (CFAR) threshold and the sector-based integration of EM energy, the first logical list representing a number of Doppler bins within the Doppler spectrum; and generating a second logical list of potential detections using the CFAR threshold and the minimum EM energy level at each Doppler bin of the EM spectrum; and The actual detections of the one or more objects are determined by performing a logical AND operation on the first and second logical lists of potential detections at each Doppler bin.

11. The radar system of claim 1, wherein, The transmitter and the receiver operate as part of a multiple-input and multiple-output (MIMO) radar method.

12. The radar system of claim 1, wherein, The radar system is configured for installation on an automobile.

13. A computer-readable storage medium comprising computer-executable instructions that, when executed, cause a processor of a radar system to: receive, via a first number of receivers, 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 different than the first number, the received EM signals comprising a third number of channels, the third number being equal to a product of the first number and the second number, at least one of the transmitted EM signals or the received EM signals comprising a phase shift between the channels; divide a Doppler spectrum of the received EM signals into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum, wherein: the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; or the sectors are unequal in size within the Doppler spectrum and the fourth number is equal to the third number; or a subset of the sectors are equal in size within the Doppler spectrum and another subset of the sectors are unequal in size within the Doppler spectrum; and the fourth number is equal to the third number; associate each channel of the received EM signals with a respective one of the sectors to form an asymmetric spectrum, wherein if the fourth number of sectors is greater than the third number of channels, at least one of the sectors is not associated with a channel of the received EM signals; perform a non-coherent integration of the received EM signals across the sectors using at least one channel of the received EM signals; determine potential detections of the one or more objects based on the non-coherent integration, the potential detections comprising one or more actual detections of the one or more objects and one or more aliased detections; determine the actual detections of the one or more objects based on the potential detections; and determine a Doppler frequency associated with each of the one or more objects based on the actual detections.

14. The computer-readable storage medium of claim 13, wherein: the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; and the computer-readable storage medium comprises computer-executable instructions that, when executed, further cause the processor of the radar system to: determine the potential detections of the one or more objects by: generating a first EM spectrum of the received EM signals for a first channel of the third number of channels; and determining, using the first EM spectrum and for each of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector with a particular number of consecutive sectors, the particular number equal to the third number minus one; and determining the actual detection of the one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

15. The computer-readable storage medium of claim 13, wherein: the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; and the computer-readable storage medium comprises computer-executable instructions that, when executed, further cause the processor of the radar system to: determine the potential detection of the one or more objects by: generating, for a first channel of the third number of channels, a first EM spectrum of the received EM signal; performing, based on the sectors, a particular number of cyclic shifts on the first EM spectrum to generate the particular number of additional EM spectra of the received EM signal, the particular number equal to the third number minus one; and determining, using the first EM spectrum and the additional EM spectra and for each of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector across the first EM spectrum and the additional EM spectra; and determining the actual detection of the one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

16. The computer-readable storage medium of claim 13, wherein: the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; and the computer-readable storage medium comprises computer-executable instructions that, when executed, further cause the processor of the radar system to: determine the potential detection of the one or more objects by: generating, for a first channel of the third number of channels, a first EM spectrum of the received EM signal; performing, based on the sectors, a particular number of cyclic shifts on the first EM spectrum to generate the particular number of additional EM spectra of the received EM signal, the particular number equal to the third number minus one; determining, using the first EM spectrum and the additional EM spectra and for each of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector across the first EM spectrum and the additional EM spectra; determining, across the first EM spectrum and the additional EM spectra, a minimum EM energy level at each Doppler bin of the EM spectrum; generating a first logical list of potential detections using the sector-based integration of the CFAR threshold and the EM energy, the first logical list representing a number of Doppler bins within the Doppler spectrum; and generating a second logical list of potential detections using the CFAR threshold and the minimum EM energy level at each Doppler bin of the EM spectrum; and determining the actual detections of the one or more objects by performing a logical "AND" operation on the first and second logical lists of potential detections at each Doppler bin.

17. A method for a radar system, the method comprising: receiving, via a first number of receivers, 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 different than the first number, the received EM signals comprising a third number of channels, the third number being equal to a product of the first number and the second number, at least one of the transmitted EM signals or the received EM signals comprising a phase shift between the channels; dividing a Doppler spectrum of the received EM signals into a fourth number of sectors, the sectors representing respective frequency ranges within the Doppler spectrum, wherein: the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; or the sectors are unequal in size within the Doppler spectrum and the fourth number is equal to the third number; or a subset of the sectors are equal in size within the Doppler spectrum and another subset of the sectors are unequal in size within the Doppler spectrum; and the fourth number is equal to the third number; associating each channel of the received EM signals with a respective sector of the sectors to form an asymmetric spectrum, wherein if the fourth number of sectors is greater than the third number of channels, at least one of the sectors is not associated with a channel of the received EM signals; performing a non-coherent integration of the received EM signals across the sectors using at least one channel of the received EM signals; determining potential detections of the one or more objects based on the non-coherent integration, the potential detections comprising one or more actual detections and one or more aliased detections of the one or more objects, determining the actual detections of the one or more objects based on the potential detections; and determining a Doppler frequency associated with each of the one or more objects based on the actual detections.

18. The method of claim 17, wherein the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; and the method further comprises: determining the potential detections of the one or more objects by: generating a first EM spectrum of the received EM signals for a first channel of the third number of channels; and determining, using the first EM spectrum and for each sector of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector with a certain number of consecutive sectors, the certain number equal to the third number minus one; and determining the actual detection of the one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

19. The method of claim 17, wherein the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; and the method further comprises: determining the potential detection of the one or more objects by: generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; performing a certain number of cyclic shifts of the first EM spectrum based on the sectors to generate the certain number of additional EM spectra of the received EM signal, the certain number equal to the third number minus one; and determining, using the first EM spectrum and additional EM spectra and for each sector of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector across the first EM spectrum and additional EM spectra; and determining the actual detection of the one or more objects by determining a maximum EM energy level of the sector-based integration of EM energy.

20. The method of claim 17, wherein the sectors are equal in size within the Doppler spectrum and the fourth number is equal to or greater than the third number plus one; and the method further comprises: determining the potential detection of the one or more objects by: generating a first EM spectrum of the received EM signal for a first channel of the third number of channels; performing a certain number of cyclic shifts of the first EM spectrum based on the sectors to generate the certain number of additional EM spectra of the received EM signal, the certain number equal to the third number minus one; determining, using the first EM spectrum and additional EM spectra and for each sector of the fourth number of sectors, a sector-based integration of EM energy that sums the EM energy of the respective sector across the first EM spectrum and additional EM spectra; determining a minimum EM energy level at each Doppler bin of the EM spectrum across the first EM spectrum and additional EM spectra; generating a first logical list of potential detections using a constant false alarm rate (CFAR) threshold and the sector-based integration of EM energy, the first logical list representing a number of Doppler bins within the Doppler spectrum; and generating a second logical list of potential detections using the CFAR threshold and the minimum EM energy level at each Doppler bin of the EM spectrum; and The actual detections of the one or more objects are determined by performing a logical AND operation on the first and second logical lists of potential detections at each Doppler bin.

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