Radar system

Abstract

Aspects of the present disclosure provide a radar system that includes a radar IC (300) including a timing engine (342), a local oscillator (330), and a modulator (350). The timing engine is configured to generate one or more chirp control signals. The local oscillator is configured to receive the one or more chirp control signals and generate a frame including a first chirp sequence from the one or more chirp control signals. The modulator is configured to modulate the first chirp sequence to generate a second chirp sequence such that the frame includes the first chirp sequence and the second chirp sequence offset by a first frequency value.

Description

Background Technology

[0001] Frequency modulated continuous wave (FMCW) radar systems can be embedded in a variety of applications, such as industrial and automotive applications. For example, an embedded FMCW radar system can be included in a vehicle to provide data for adaptive cruise control, collision warning, blind spot assist / warning, lane change assist, parking assist, and more. In other examples, embedded FMCW radar systems in industrial applications can provide data to help navigate autonomous equipment in a factory, track motion, and so on. Summary of the Invention

[0002] This disclosure provides a radar system. In one example, the radar system includes a radar transceiver integrated circuit (IC). The radar transceiver IC includes a timing engine, a local oscillator coupled to the timing engine, and a modulator coupled to the local oscillator. The timing engine is configured to generate one or more linear frequency modulated (LFM) pulse control signals. The local oscillator is configured to receive one or more LFM pulse control signals and generate a frame including a first LFM pulse sequence based on the one or more LFM pulse control signals. The modulator is configured to modulate the first LFM pulse sequence to generate a second LFM pulse sequence, such that the frame includes the first LFM pulse sequence and the second LFM pulse sequence offset from a first frequency value.

[0003] Other aspects of this disclosure provide a method for determining an approximate velocity in a radar system. In one example, the method includes initiating the transmission of a linear frequency modulated (LFM) pulse frame having a first LFM pulse sequence and a second LFM pulse sequence offset by a frequency (Δf) from the first LFM pulse sequence via a transmit channel. The method further includes receiving a reflected LFM pulse frame via a receive channel, the reflected LFM pulses including the first LFM pulse sequence and the second LFM pulse sequence reflected by an object within the field of view of the radar system. The method further includes generating a digital intermediate frequency (IF) signal corresponding to the reflected LFM pulse frame via the receive channel. The method further includes demodulating the digital IF signal via a processor to form a first demodulated IF signal corresponding to the first LFM pulse sequence and a second demodulated IF signal corresponding to the second LFM pulse sequence, and determining an approximate velocity via the processor at least partially based on the first demodulated IF signal and the second demodulated IF signal.

[0004] Other aspects of this disclosure provide a method for determining velocity in a radar system. In one example, the method includes calculating a first velocity estimate via a processing element based on at least one range Doppler array, the at least one range Doppler array being obtained based on transmitting linearly frequency modulated (LFM) pulse frames having a first LFM pulse sequence and a second LFM pulse sequence offset by Δf from the first LFM pulse sequence. The method further includes calculating a second velocity estimate via a processing element based on a phase difference of a first peak in at least one range Doppler array and at least one second range Doppler array, wherein at least one second range Doppler array is obtained based on transmitting LFM pulse frames having a first LFM pulse sequence and a second LFM pulse sequence offset by Δf from the first LFM pulse sequence. The method further includes calculating a velocity via a processing element based on the first velocity estimate and the second velocity estimate. Attached Figure Description

[0005] For a detailed description of the various examples, reference will now be made to the accompanying drawings, in which:

[0006] Figure 1 It is a waveform diagram illustrating linear frequency modulated pulse transmission;

[0007] Figure 2 A block diagram illustrating a frequency modulated continuous wave (FMCW) radar system is shown.

[0008] Figure 3 A block diagram illustrating a radar transceiver integrated circuit (IC) is shown;

[0009] Figure 4 A flowchart illustrating a method for FMCW radar is shown;

[0010] Figure 5 A schematic diagram illustrating a range Doppler array is shown;

[0011] Figure 6 A flowchart illustrating a method for initiating the transmission of a linear frequency modulated pulse frame is shown;

[0012] Figure 7 A flowchart illustrating a method for determining the velocity of an object detected by an FMCW radar system is shown.

[0013] Figure 8 A flowchart illustrating a method for calibrating an FMCW radar system is shown; and

[0014] Figure 9 A flowchart illustrating a method for calibrating an FMCW radar system is shown. Detailed Implementation

[0015] At least some examples of frequency modulated continuous wave (FMCW) radar systems transmit frames containing a series of frequency ramps called linear frequency modulated pulses. These linear frequency modulated pulses may be reflected back to the FMCW radar system by a subject object. Upon receiving a signal containing the reflected linear frequency modulated pulses, the FMCW radar system can down-convert, digitize, and process the received signal to determine the characteristics of the subject object. When the subject object is in the field of view of the FMCW radar system, these characteristics may include the subject object's range, velocity, angle of arrival, etc. At least some examples of FMCW radar systems are capable of accurately estimating the velocity of the subject object up to a maximum determined velocity. For subject objects with velocities greater than the maximum determined velocity, the velocity of the subject object measured by the FMCW radar system may be inaccurate in one or both of the velocity amplitude and / or sign.

[0016] In at least some FMCW radar systems, multiple linear frequency modulated (LFM) pulse sequences (e.g., consecutive, equally spaced LFM pulse sequences) are transmitted and the reflections of these LFM pulses are received to generate a radar signal. After each LFM pulse sequence, there may be a period of idle time (e.g., inter-frame idle time) to allow processing of the radar signal generated by the reflected LFM pulses. The acquisition time of the LFM pulse sequence, together with the subsequent inter-frame idle time, can form a radar frame. In at least one example, the reflected signal received by each antenna of the FMCW radar system is mixed with the transmitted signal to generate a filtered and digitized intermediate frequency (IF) signal. Signal processing can then be performed on the resulting digital IF signal (e.g., one for each receiving antenna in the FMCW radar system) to extract any one or more of the range, velocity, and / or angle of potential objects in the radar field of view.

[0017] In at least one example, for each receive channel (e.g., the receive antenna and / or associated processing hardware in an FMCW radar system), a range fast Fourier transform (FFT) is performed on a digitized sample of each reflected linear frequency modulated (LFM) pulse to convert the data from the time domain to the frequency domain. At least some peaks in the resulting frequency domain array correspond to the range (distance) of the potential object. In some examples, the results of the range FFT are stored in memory, for example, for further processing. In some examples, the FMCW radar system may generate a set of range FFT results (e.g., a range array (or range matrix)) for each receive antenna in the FMCW radar system. In at least one example, if there are N time samples in the LFM pulse, N distance results corresponding to a specific range bin are stored for each LFM pulse. Similarly, if there are M LFM pulses in the LFM pulse sequence, an array of M x N distance values ​​is generated by the range FFT, where the N columns are signal values ​​across the corresponding range bins of the M LFM pulses.

[0018] In at least one example, for each range array, a Doppler FFT is performed on each of the corresponding range values ​​of the linearly frequency-modulated pulses in the linearly frequency-modulated pulse sequence. For example, a Doppler FFT is performed on each of the N columns of an MxN array. At least some peaks in the resulting MxN range-Doppler plane (also referred to as a range-Doppler array or range-Doppler slice) correspond to the range and relative velocity (e.g., speed) of a potential object in the radar field of view. In at least one example, the FMCW radar system generates a range-Doppler array for each receiving antenna of the FMCW radar system.

[0019] In at least some examples, the FMCW radar system then processes a range Doppler array to determine information about at least some potential objects in the radar's field of view. When multiple receivers, each connected to a receiving antenna, are used, each reflected signal may have a different delay depending on the angle at which the object reflects the signal. In at least one example, potential objects in the radar's field of view are detected by taking into account peaks in the range Doppler array. Information about the potential objects can then be used to apply specific processing, such as object tracking, object movement rate, direction of movement, etc. In an automotive environment, object data can be used for any one or more of, for example, lane change assist, parking assist, blind spot detection, rear collision warning, emergency braking, and / or cruise control.

[0020] In at least one example, the FMCW radar system estimates the velocity of a potential object in the radar field of view by measuring the phase difference between consecutively received linear frequency modulated pulses. In some examples, a large linear frequency modulated pulse period (T) c (For example, the time elapsed from the start of one linear frequency modulated pulse in a linear frequency modulated pulse sequence to the start of the next linear frequency modulated pulse) can cause a phase flip, thus introducing errors in velocity estimation. In at least one example, the maximum achievable velocity (v) of an FMCW radar system is... max ) and T c Inversely proportional. In at least one example, Where λ is the wavelength corresponding to the start frequency of the linearly frequency-modulated pulse. However, various factors may limit the minimum achievable T. c This limits the number of realizable v. max For example, such factors may include the bandwidth spanned by the linear frequency modulated pulse, the slope of the linear frequency modulated pulse, and, in some FMCW radar systems, the sequential transmission of multiple transmitters.

[0021] In some examples, the bandwidth of the linear frequency modulated (LFM) pulse affects range resolution (e.g., a larger LFM pulse bandwidth results in better range resolution). However, increasing the LFM pulse bandwidth to improve range resolution also increases T0. c And reduce v maxFurthermore, the maximum slope of a linear frequency modulated (LFM) pulse may be limited by the bandwidth of the LFM pulse generation circuit system, the IF bandwidth of the receiving channel, and the maximum range supported by the radar. For a given bandwidth spanned by the LFM pulse, as the LFM pulse slope decreases, T... c Increase and decrease v max In an example of an FMCW radar system that provides a time-division multiplexed multiple-input multiple-output (TDM-MIMO) operating mode (e.g., which can improve angular resolution), multiple transmitters transmit sequentially, which can increase the effective T... c And reduce v max In the context of TDM-MIMO, T c Defined as the time elapsed from the start of one linear frequency modulated pulse emitted from the same transmitter to the start of the next linear frequency modulated pulse. Therefore, in an FMCW radar system, the time that exists and is determined by the minimum realizable T... c Within the imposed limitations, increase v max And difficulties have arisen.

[0022] At least some aspects of this disclosure provide for enhancing radar systems such as FMCW radar systems. max In at least some examples, the FMCW radar system implements a radar transceiver integrated circuit (IC) configured to be coupled to one or more antennas (e.g., transmit antennas and / or receive antennas) to transmit linear frequency modulated (LFM) pulses and receive reflected LFM pulses. For example, the radar transceiver IC generates equally spaced LFM pulse frames and provides these LFM pulse frames to at least one transmit antenna for transmission. In at least some examples, before providing the LFM pulse frames to the transmit antennas, the radar transceiver IC modulates the LFM pulses in the frames to convert a single LFM pulse sequence into two LFM pulse sequences separated by a frequency interval Δf. In at least some examples, the Δf in the field of view of the radar transceiver IC's bandwidth is relatively small. For example, Δf is approximately 0.01 GHz in some embodiments, such as in systems where the first LFM pulse spans a frequency range of 79.1 GHz to 80.1 GHz and a second LFM pulse spaced Δf from the first LFM pulse spans a frequency range of 79.11 GHz to 80.11 GHz. In other examples, Δf takes any suitable value. For example... Figure 1 As shown, the first linear frequency modulated pulse in the first sequence can begin at time t and frequency α, where the horizontal axis represents time and the vertical axis represents frequency. The first linear frequency modulated pulse in the second sequence can begin at the same time t and frequency α + Δf. Similarly, the second linear frequency modulated pulse in the first sequence can begin at time t + T. c It begins at frequency α. The second linearly modulated pulse in the second sequence can occur at the same time t+T.c And it begins at frequency α+Δf. In this way, in at least some examples, the corresponding linear frequency modulated pulses (e.g., the same linear frequency modulated pulses of the first and second sequences) are frequency-intervalped by frequency Δf at any given time t and time-intervalped by time ΔT at any given frequency f, where And S is the slope of the linear frequency modulated pulse.

[0023] Although the illustration shows a frame with two sequences of linear frequency modulated pulses that include only two pulses offset by Δf, the FMCW radar system of this disclosure can be applied to frames with sequences including more than two linear frequency modulated pulse sequences and / or sequences each including more than two linear frequency modulated pulses, wherein each linear frequency modulated pulse sequence is offset by a certain frequency, and such examples are included within the scope of this disclosure. In one example, in order to at least partially compensate for the minimum achievable T c The imposed restrictions, the linear frequency modulated pulses in the modulated frame to facilitate the disclosed FMCW radar system v max In at least one example, reducing the time interval between the linear frequency modulated pulse sequence in a frame and its corresponding modulated linear frequency modulated pulse sequence increases the v of the FMCW radar system. max Simultaneously utilizing a single radar transceiver IC. When ΔT is much smaller than T. c In one example, the v of the FMCW radar system max Increased by approximately The magnitude of Δf is given by a factor. In one example, the magnitude value of Δf can be chosen such that the corresponding ΔT is greater than the maximum round-trip delay from the FMCW radar system to the farthest object and back to the FMCW radar system. In one example, this provides that the reflection corresponding to the first linear frequency modulated pulse sequence does not overlap with the reflection corresponding to the second linear frequency modulated pulse sequence in the frequency domain. In one example, this staggered reflection further allows the reflections to be spaced out and allows digital processing to be performed on the reflections. In an example where a third linear frequency modulated pulse sequence also exists, the time difference between any pair of linear frequency modulated pulse sequences is greater than the aforementioned round-trip delay. In one example, the farthest object is an object (if present) capable of generating a reflection signal with significant intensity received at the FMCW radar system that can disrupt the FMCW radar system's detection of signals corresponding to other linear frequency modulated pulse sequences or can be disrupted by other such reflection signals existing from multiple linear frequency modulated pulse sequences. If the farthest object corresponds to T farthest If the round-trip delay is F, then farthest =S*T farthest It can be the estimated maximum IF frequency of the FMCW radar system.

[0024] Now for reference Figure 2 , Figure 2 A block diagram of an illustrative FMCW radar system 200 is shown. In at least one example, the FMCW radar system 200 includes a radar transceiver IC 205 and a processing unit 210. In some examples, the FMCW radar system 200 further includes a transmitting antenna 215 and a receiving antenna 220, while in other examples, the FMCW radar system 200 does not include the transmitting antenna 215 and the receiving antenna 220 but is configured to be coupled to the transmitting antenna 215 and the receiving antenna 220. The illustrative architecture of the radar transceiver IC 205 is shown in... Figure 3 The diagram is shown in the image below and described in the image below.

[0025] In at least one example, radar transceiver IC 205 may be referred to as the front end of FMCW radar system 200 and processing unit 210 may be referred to as the back end of FMCW radar system 200. In at least one example, radar transceiver IC 205 and processing unit 210 are implemented separately and may be configured to be coupled together, while in other examples, radar transceiver IC 205 and processing unit 210 are implemented together, for example, together in a single-chip package or system-on-a-chip (SoC) (e.g., a single integrated circuit). In the example where radar transceiver IC 205 and processing unit 210 are implemented on the SoC, radar transceiver IC 205 may correspond to a sub-circuit of the IC forming the SoC. In at least one example, processing unit 210 is coupled to radar transceiver IC 205 via interface 225, which can facilitate any suitable communication method (e.g., a serial interface or a parallel interface) and is configured to receive data from radar transceiver IC 205 and / or transmit data to radar transceiver IC 205.

[0026] In at least one example, interface 225 may be a high-speed serial interface such as a Low Voltage Differential Signaling (LVDS) interface. In another example, interface 225 may be a low-speed interface such as a Serial Peripheral Interface (SPI). In at least one example, radar transceiver IC 205 includes functionality for generating one or more digital IF signals (which may alternatively be referred to as de-FLEMET pulse signals, beat signals, or raw radar signals) from reflected linear frequency modulated pulses received via receiving antenna 220. Furthermore, in at least one example, radar transceiver IC 205 includes functionality for performing at least a portion of signal processing on the radar signals received in radar transceiver IC 205 (e.g., reflected linear frequency modulated pulses and / or digital IF signals) and providing the result of such signal processing to processing unit 210 via interface 225. In at least one example, radar transceiver IC 205 performs a range FFT on each received frame of radar transceiver IC 205 (e.g., each linear frequency modulated pulse sequence of the frame). In at least some examples, the radar transceiver IC 205 also performs a Doppler FFT on each received frame (e.g., after performing a range FFT and based on the result of the range FFT).

[0027] In at least one example, the processing unit 210 includes functions for processing data received from the radar transceiver IC 205 to, for example, determine any one or more of the distance, velocity, and / or angle of any object detected by the FMCW radar system 200. In some examples, the processing unit 210 may also, or alternatively, include functions for performing post-processing of information about the detected object, such as tracking the object, determining the rate and direction of motion, etc. In at least one example, the processing unit 210, for example, provides an additional v according to the present disclosure for the FMCW radar system 200. max In terms of determining the velocity of the detected object, the processing unit 210 includes, in various examples, any one or more suitable processors or combinations of processors required for processing data received from and / or providing data to the radar transceiver IC 205. For example, the processing unit 210 may include one or more of a digital signal processor (DSP), a microcontroller, a system-on-a-chip (SoC) combining DSP and microcontroller processing, a field-programmable gate array (FPGA), or any combination thereof.

[0028] Now for reference Figure 3 , Figure 3 A block diagram of an illustrative radar transceiver IC 300 is shown. In at least some examples, the radar transceiver IC 300 is suitable for implementation as Figure 2The radar transceiver IC 205 is used in the FMCW radar system 200. In other examples, the radar transceiver IC 300 is suitable for implementation in other radar systems. In at least one example, the radar transceiver IC includes one or more transmit channels 304 and one or more receive channels 302A-302N (where N is any positive integer). Each of the transmit channel 304 and the receive channels 302A-302N can be individually coupled to a transmit antenna or a receive antenna, such as transmit antenna 215 or receive antenna 220, as described above regarding... Figure 2 What is being discussed, rather than as Figure 3 As shown. Although illustrated for simplicity as including two receive channels 302A and 302N and one transmit channel 304, in various examples, the radar transceiver IC 300 may include any suitable number of receive channels 302N and / or any suitable number of transmit channels 304. Furthermore, the number of receive channels 302N and the number of transmit channels 304 may be different.

[0029] In at least one example, transmit channel 304 includes a power amplifier (PA) 307 coupled between a transmit antenna (not shown) and an I / Q modulator 350 to amplify the output of the I / Q modulator 350 for transmission via the first transmit antenna. In at least some examples, each additional transmit channel 304 may be substantially similar and may be coupled to its own respective transmit antenna (not shown) or the same transmit antenna.

[0030] In at least one example, the first receiving channel 302A includes a low-noise amplifier (LNA) 303A coupled between a receiving antenna (not shown) and a mixer 306A to amplify a radio frequency (RF) signal (e.g., a reflected linear frequency modulated pulse) received via the receiving antenna before providing the amplified signal to the mixer 306A. In at least one example, the mixer 306A is coupled to a clock multiplier 340 and configured to receive a clock signal from the clock multiplier 340, for example, to mix with the received RF signal to generate an IF signal. In at least one example, a baseband bandpass filter 310A is coupled to the mixer 306A and configured to filter the IF signal, a variable gain amplifier (VGA) 314A is coupled to the baseband bandpass filter 310A and configured to amplify the filtered IF signal, and an analog-to-digital converter (ADC) 318A is coupled to the VGA 314A and configured to convert the analog IF signal to a digital IF signal. The baseband bandpass filter 310A, VGA 314A, and ADC 318A of each receive channel 302A can be collectively referred to as analog baseband, baseband chain, complex baseband, or baseband filter chain. Furthermore, the baseband bandpass filter 310A and VGA 314A can be collectively referred to as IF amplifiers (IFAs). In at least some examples, each additional receive channel 302N can be substantially similar to the first receive channel 302A and can be coupled to its own respective receive antenna (not shown) or the same receive antenna. For example, each receive channel 302N may include an LNA 303N, a mixer 206N, a baseband bandpass filter 310N, a VGA 314N, and an ADC 318N. In at least one example, the ADC 318A is coupled to a digital front-end (DFE) 322, for example, to provide a digital IF signal to the DFE 322. The DFE 322 (also referred to as a digital baseband) includes, in at least one example, the capability to perform decimation filtering or other processing operations on the digital IF signal, such as reducing the data transmission rate of the digital IF signal. In various examples, the DFE 322 may also perform other operations on the digital IF signal, such as DC offset removal and / or compensation (e.g., digital compensation) for non-ideals in the receive channels 302A-302N (e.g., inter-receiver gain imbalance non-ideal, inter-receiver phase imbalance non-ideal, etc.). In at least one example, the DFE 322 is coupled to a signal processor 344 and configured to provide the output of the DFE 322 to the signal processor 344.

[0031] In at least one example, the signal processor 344 is configured to perform at least a portion of signal processing on the digital IF signal generated from the received radar frame, and to transmit the result of such signal processing via terminal 352 and / or terminal 354. In at least one example, the signal processor 344 transmits the result of the signal processing to a processing unit (not shown), such as as described above. Figure 2 The processing unit 210 is described. In various examples, the results are provided from the signal processor 344 to the terminals 352 and / or 354 via the high-speed interface 324 and / or SPI 328, respectively. In at least one example, the signal processor 344 performs a range FFT on each linear frequency modulated pulse sequence in the received radar frame. In at least one example, the signal processor 344 further performs a Doppler FFT on the results of the range FFT.

[0032] Signal processor 344 may include any suitable processor or combination of processors. For example, signal processor 344 may be a DSP, microcontroller, FFT engine, DSP plus microcontroller processor, FPGA, or application-specific integrated circuit (ASIC). In at least one example, signal processor 344 is coupled to memory 348, for example, to store in memory 348 intermediate results of partial signal processing performed on a digital IF signal and / or to read instructions from memory 348 for execution by signal processor 344.

[0033] In at least one example, memory 348 provides on-chip storage (e.g., a non-transitory computer-readable storage medium) for storing software programs executed by a processor on the radar transceiver IC 300, for example, for transferring data between various components of the radar transceiver IC 300. Memory 348 may include any suitable combination of read-only memory (ROM) and / or random access memory (RAM) (e.g., static RAM). In at least one example, direct memory access (DMA) component 346 is coupled to memory 348 to perform data transfer from memory 348 to high-speed interface 324 and / or SPI 328.

[0034] In at least one example, the SPI 328 provides a connection via terminal 354 between the radar transceiver IC 300 and another device (e.g., such as...). Figure 2 The radar transceiver IC 300 is an interface for communication between processing units (processing units 210, etc.). For example, the radar transceiver IC 300 can receive control information via SPI 328, such as the timing and frequency of linear frequency modulated pulses, output power levels, and triggering of monitoring functions. In at least one example, the radar transceiver IC 300 can transmit test data to, for example, processing unit 210 via SPI 328.

[0035] In at least one example, control module 326 includes functionality for controlling at least a portion of the operation of radar transceiver IC 300. Control module 326 may include, for example, a microcontroller that executes firmware to control the operation of radar transceiver IC 300. For example, control may involve providing data parameters to other components of radar transceiver IC 300 and / or providing control signals to other components of radar transceiver IC 300.

[0036] In at least one example, the programmable timing engine 342 includes functionality for receiving linear frequency modulated (LFM) pulse parameter values ​​for a LFM pulse sequence in a radar frame from the control module 326 and generating LFM pulse control signals for controlling the transmission and reception of LFM pulses in the frame based on the parameter values. In some examples, the LFM pulse parameters are defined by the radar system architecture and may include, for example, transmitter enable parameters indicating which transmit channels are enabled, LFM pulse frequency start value, LFM pulse frequency slope, ADC sampling time, ramp end time, transmitter start time, etc.

[0037] In at least one example, the radio frequency synthesizer (RFSYNTH) 330 includes the function of generating a signal (e.g., a linear frequency modulated pulse and / or a linear frequency modulated pulse sequence) for transmission based on a linear frequency modulated pulse control signal received from a programmable timing engine 342. In some examples, the RFSYNTH 330 includes a phase-locked loop (PLL) with a voltage-controlled oscillator (VCO). In at least one example, the RFSYNTH 330 may be referred to as a local oscillator (LO).

[0038] In at least one example, multiplexer 332 is coupled to RFSYNTH 330 and input buffer 336 and is configurable to select between a signal received from input buffer 336 from an external component (not shown) and a signal generated by RFSYNTH 330. In at least one example, output buffer 338 is coupled to multiplexer 332 and can, for example, provide the signal selected by multiplexer 332 to the input buffer of another radar transceiver IC (not shown). In at least one example, the multiplexer is controlled by control module 326 via a selection signal.

[0039] In at least one example, clock multiplier 340 increases the frequency of the output of multiplexer 332 (e.g., the output of RFSYNTH 330) to the operating frequency of mixer 306A. In at least one example, clear PLL 334 is configured to increase the frequency of the signal of an external low-frequency reference clock (not shown) received by radar transceiver IC 300 to the frequency of RFSYNTH 330 and filter out reference clock phase noise in the reference clock signal.

[0040] In at least one example, the I / Q modulator 350 receives the output of the clock multiplier 340 (e.g., a linear frequency modulated pulse and / or a sequence of linear frequency modulated pulses) and modulates the output of the clock multiplier 340 based on data received from the control module 326 to generate a frequency-shifted copy of the clock multiplier 340 output. In at least one example, the I / Q modulator is further coupled to a digital-to-analog converter (DAC) 356 and a DAC 358, each of which can be coupled to the control module 326. In at least one example, the DAC 356 receives 1+e from the control module 326. j2πΔft The real component, and DAC 358 receives 1+e from control module 326. j2πΔft The imaginary component is given by t, where t represents the continuous (e.g., real) time in the analog signal and the continuous (e.g., real) time of a given digital sample in the digital signal. Each of DACs 356 and 358 converts its respective received signal into an analog value and provides that analog value to I / Q modulator 350. For example, DAC 356 may provide its analog value output to the real component input of I / Q modulator 350, and DAC 358 may provide its analog value output to the in-phase component input of I / Q modulator 350.

[0041] In at least one example, the I / Q modulator 350 generates in-phase (I) and quadrature (Q) components of a clock signal received from the clock multiplier 340, multiplies the I and Q clock components by analog values ​​received from DAC 356 and DAC 358, respectively, and sums the resulting products before providing a signal to PA 307. In at least some examples, this multiplication modulates the output of the clock multiplier 340 to generate a resulting signal that includes a frequency-shifted copy of the output of the clock multiplier 340, for example, as referenced above. Figure 1 As shown and discussed, solid lines represent the output of clock multiplier 340, while dashed lines represent frequency-shifted (e.g., modulated) copies of the output of clock multiplier 340. As described above, I / Q modulator 350 can generate a complex-valued modulated signal comprising a first linear frequency modulated (LFM) pulse sequence and a second LFM pulse sequence, the second LFM pulse sequence being frequency-shifted by Δf relative to the first LFM pulse sequence. The complex-valued modulated signal can include an in-phase component corresponding to the real part of the complex-valued signal and a quadrature-phase component corresponding to the imaginary part of the complex-valued signal.

[0042] Receive channel 302A in Figure 3The diagram illustrates the actual receive channel. In at least one example, the actual receive channel has a bandwidth of 0 to 2Δf (e.g., the bandwidths of the baseband bandpass filter 310A, VGA 314A, and ADC 318A can be at least 0 to 2Δf). In other examples not shown, the receive channel 302A can be implemented as a composite receive channel. In at least one example, the composite receive channel includes copies (not shown) of at least some of the following: LNA 303A, mixer 306A, baseband bandpass filter 310A, VGA 314A, and / or ADC 318A. In at least one example, the composite receive channel has a bandwidth of -Δf to Δf. When the receive channel 302A is implemented as a composite receive channel, mixer 306A can receive the I component of the clock signal generated by clock multiplier 340, and a copy of mixer 306A can receive the Q component of the clock signal generated by clock multiplier 340, such that mixer 306A and the copy of mixer 306A operate with a 90-degree phase difference. In various examples, the I and Q components of the clock signal can be generated by an I / Q splitter (not shown) that receives the clock signal generated by clock multiplier 340. For example, the signals generated by the I / Q splitter have a 90-degree phase difference. In some examples, the I / Q splitter is implemented as a discrete component of radar transceiver IC 300, while in other examples it is implemented as part of I / Q modulator 350.

[0043] Now for reference Figure 4 , Figure 4 It shows that v can be increased max A flowchart illustrating an FMCW radar method 400. In at least some examples, method 400 is performed by an FMCW radar system (such as...). Figure 2 The FMCW radar system 200 is implemented, for example, at least in part by a radar transceiver IC (such as...). Figure 2 Radar transceiver IC 205 and / or Figure 3 The radar transceiver IC 300 is implemented.

[0044] At operation 405, the FMCW radar system initiates the transmission of a linear frequency modulated (LFM) pulse frame having a first LFM pulse sequence and a second LFM pulse sequence offset by Δf from the first LFM pulse sequence. The following is in conjunction with... Figure 6 The process of initiating the transmission of a linear frequency modulated pulse frame is further described.

[0045] At operation 410, the FMCW radar system receives reflected linear frequency modulated (LFM) pulse frames and generates digital IF signals for each receiving antenna of the FMCW radar system. In at least one example, the FMCW radar system generates digital IF signals by combining the received LFM pulse frames with LFM pulses output from clock multiplier 340 (e.g., mixing or multiplying), for example, by using a mixer to filter the combined signal, amplify the filtered signal, and convert the filtered signal from analog to digital format to form the digital IF signal. In some examples, the radar system may include an I / Q demodulator that demodulates the received LFM pulse frames with LFM pulses output from clock multiplier 340 to generate the in-phase component of the digital IF signal, and further demodulates the received LFM pulse frames with a 90-degree phase-shifted version of the LFM pulses output from clock multiplier 340 to generate the quadrature component of the digital IF signal. The in-phase and quadrature components of the digital IF signal can together form a complex-valued digital IF signal.

[0046] At operation 415, the FMCW radar system demodulates the digital IF signal. For example, when a linear frequency modulated (LFM) pulse frame transmitted by the FMCW radar system (e.g., at operation 405) and subsequently received as a reflected LFM pulse frame (e.g., at operation 410) comprises two LFM pulse sequences offset by Δf, the digital IF signal can similarly contain reflected LFM pulse data corresponding to the two sequences and separated by a Δf interval in the digital IF signal. To access data from the two LFM pulse sequences, in at least one example, the FMCW radar system demodulates the digital IF signal and / or performs a first FFT on the digital IF signal to obtain data from the LFM pulses that initially belong to the first LFM pulse sequence. In at least some examples, the FMCW radar system may further demodulate the digital IF signal by Δf (or perform an equivalent FFT process) to compensate for the frequency offset of Δf, in order to obtain data from the LFM pulses that initially belong to the second LFM pulse sequence offset by Δf from the first LFM pulse sequence. In at least one example, FFT and / or demodulation are performed in the signal processor of the radar transceiver IC of the FMCW radar system. In another example, the digital IF signal is transmitted to the processing unit of the FMCW radar system that performs FFT and / or demodulation. In one example, demodulation and FFT are implemented as separate subsets of operation 415, while in other examples, demodulation includes the execution of one or more FFTs and / or the processing of one or more FFT intervals.

[0047] In one example, the digital IF signal contains the sum of signals corresponding to reflections from the object, which correspond to both a first linear frequency modulated (LFM) pulse sequence and a second LFM pulse sequence. In the digital IF signal, the signal offset frequency corresponding to the first and second LFM pulse sequences is Δf. Optionally, this can be achieved through digital processing (e.g., multiplying time-domain digital data by e). -j2πΔft (Sometimes referred to as frequency shift) This generates a new version of the digital IF signal corresponding to the second linearly frequency-modulated (LFM) pulse sequence. In this new version of the digital IF signal, the signal corresponding to the second LFM pulse sequence occupies the same frequency range as the signal corresponding to the first LFM pulse sequence in the original version of the digital IF signal. To enable further digital processing (e.g., performing a distance-dimensional FFT), the new version of the digital IF signal can be filtered by a digital filter to suppress frequencies outside the range of interest (e.g., 0 to F). farthest The frequency components of the first linear frequency modulated (LFM) pulse sequence are sampled. The new version of the digital IF signal generated at the output of the digital filter can be referred to as the demodulated digital IF signal corresponding to the second LFM pulse sequence. The original digital IF signal itself can (e.g., without any frequency shift) be passed through a similar digital filter to suppress frequency components beyond the actual frequency of interest, and is referred to as the demodulated version of the first LFM pulse sequence (or the demodulated digital IF signal corresponding to the first LFM pulse sequence). Any third LFM pulse sequence, if present, can undergo processing similar to the second LFM pulse sequence, except that Δf is replaced by the corresponding frequency difference between the first and third LFM pulse sequences. In some examples, the demodulated digital IF signal of the second (and / or subsequent) LFM pulse sequence is sampled with a delay of ΔT (or an integer multiple of ΔT) compared to the sampled demodulated digital IF signal corresponding to the first LFM pulse sequence. In some examples, this sampling delay causes the demodulated digital IF signals of the first, second, and any subsequent LFM pulse sequences to correspond to substantially the same starting RF frequency. The demodulated digital RF signal discussed herein is sampled according to this delay.

[0048] At operation 420, the FMCW radar system performs a range FFT on each demodulated digital IF signal to generate a range array for each demodulated digital IF signal. For example, the radar system may perform a first range FFT on a first demodulated digital IF signal and a second range FFT on a second demodulated digital IF signal, where the second demodulated digital signal is a frequency-shifted version of the first digital demodulated signal. Each range FFT operation can generate an M x N range array (or range matrix), where M is the number of linear frequency modulated pulses in the linear frequency modulated pulse sequence, and N is the number of time samples of the received linear frequency modulated pulses. N may also correspond to the number of range intervals in the range array. In some examples, the range FFT operation can be performed on each linear frequency modulated pulse sequence received by each receiving antenna of the FMCW radar system. In at least one example, the corresponding range FFT is performed in the signal processor of the radar transceiver IC of the FMCW radar system, and the resulting range array is transmitted to the processing unit of the FMCW radar system. In another example, the demodulated digital IF signal is transmitted to the processing unit of the FMCW radar system that performs the range FFT.

[0049] In another example, the digital IF signal can be used to directly perform a distance FFT without performing demodulation as described above. In such an example, the length of the FFT can be doubled (e.g., to store information corresponding to both the first and second linear frequency modulated pulse sequences). In this case, it corresponds to, for example, from 0 to F... farthest The distance FFT interval of the frequency range will contain the distance FFT values ​​corresponding to the first linear frequency modulated pulse sequence. In the same case, this corresponds to, for example, from Δf to Δf+F. farthest The distance FFT interval of the frequency will contain the distance FFT values ​​corresponding to the second linear frequency modulated pulse sequence. Any third sequence will similarly correspond to 2Δf to 2Δf+F. farthest (For example, the resulting distance FFT must be three times longer to preserve information corresponding to the first, second, and third linear frequency modulated pulse sequences).

[0050] At operation 425, the FMCW radar system performs a Doppler FFT on each range array generated at operation 420 to generate a corresponding range-Doppler array (or range-Doppler matrix). For example, a Doppler FFT is performed on each of the N columns of each range array generated at operation 420. In some examples, operation 425 may generate a first range-Doppler array corresponding to a first linear frequency modulated pulse sequence and a second range-Doppler array corresponding to a second linear frequency modulated pulse sequence.

[0051] At operation 430, the FMCW radar system determines the velocity of potential objects in its field of view based on each range Doppler array. In at least one example, peaks in the range Doppler array indicate potential objects, and the velocities of these potential objects are determined by the positions of the individual peaks in the range Doppler array. An example of a range Doppler array is shown below. Figure 5 As shown. In this example, MxN array 500 represents a range Doppler array corresponding to a first linear frequency modulated pulse sequence from a received radar frame, and MxN array 502 represents a range Doppler array corresponding to a second linear frequency modulated pulse sequence from a received radar frame. In at least some examples, the shaded boxes of arrays 500 and 502 indicate peaks in the respective arrays corresponding to potential objects in the field of view of the FMCW radar system. In at least one example, the number of rows and columns of peaks in the range Doppler arrays correspond to the velocity and range of potential targets in the field of view of the FMCW radar system, respectively. In at least one example, the velocity of potential objects is further refined by finding differences in the phases of peaks in the range Doppler arrays, for example, as referenced below. Figure 7 As described. In the example where a longer FFT (e.g., a 2N-point FFT) is performed instead of demodulation, array 500 can be generated by extracting the interval corresponding to the first half (e.g., 0 to N-1) of the longer FFT, and array 502 can be generated by extracting the interval corresponding to the second half (e.g., N to 2N-1) of the longer FFT. In one example, to delay sampling the demodulated digital IF signal corresponding to the second linear frequency modulated pulse sequence (and subsequent linear frequency modulated pulse sequences) by ΔT (or an integer multiple of ΔT), the phase of the value in each distance interval of array 502 is modified by adding 2*π*IF*ΔT, where IF is the phase of the signal relative to the first half (e.g., 0 to N-1) of the second linear frequency modulated pulse sequence (and subsequent linear frequency modulated pulse sequences). The given distance interval corresponds to the frequency value, where Fs is the sampling rate, N is the number of samples per linear frequency modulated pulse, and n is the distance interval exponent from 0 to N-1.

[0052] In one example, when determined solely based on the number of rows of one or more range Doppler arrays, the maximum definite velocity of a potential object in the field of view of an FMCW radar system might be V1, and the FMCW radar system will estimate... and The speed between. If there exists an object with velocity p*V1+v in the field of view of the FMCW radar system, where p is an integer (positive or negative), and V from... to An FMCW radar system can determine the velocity of an object as V without error based on the number of rows of one or more range Doppler arrays when p is non-zero. The FMCW radar system then determines an approximation of the object's actual velocity (e.g., via Equation 3 discussed below). The FMCW radar system further refines the calculation of the object's velocity by determining the object's velocity as a p value that is closest to the approximation of the object's actual velocity, based on the difference between the peak phases in the range Doppler arrays.

[0053] Now for reference Figure 6 , Figure 6 A flowchart illustrating a method 600 for initiating the transmission of a linear frequency modulated pulse frame is shown. In at least some examples, method 600 is performed by an FMCW radar system (such as...) Figure 2 The FMCW radar system 200 is implemented, for example, at least in part by a radar transceiver IC (such as...). Figure 2 Radar transceiver IC 205 and / or Figure 3 The radar transceiver IC300 is implemented.

[0054] At operation 605, the control module of the FMCW radar system (or alternatively, the radar transceiver IC and / or components external to the FMCW radar system) is used to generate parameter values ​​for the linear frequency modulated (LFM) pulses transmitted by the FMCW radar system and transmit them to the timing engine. In some examples, the timing engine generates an LFM pulse control signal that controls the FMCW radar system's transmission and / or reception of LFM pulses in a frame based on the parameter values. In some examples, the LFM pulse parameters are defined by the radar system architecture and may include, for example, transmitter enable parameters indicating which transmit channels are enabled, the LFM pulse frequency start value, the LFM pulse frequency slope, the ADC sampling time, the ramp end time, the transmitter start time, etc.

[0055] At operation 610, the timing engine transmits a linear frequency modulated (LFM) pulse control signal to RFSYNTH to generate one or more LFM pulses. In at least some examples, RFSYNTH may be the local oscillator of the FMCW radar system. At operation 615, the one or more LFM pulses are multiplied to increase the frequency of the one or more LFM pulses to generate an amplified LFM pulse (or a multiplied LFM pulse or a modified LFM pulse), for example, to match the operating frequency of the receiving component of the FMCW radar system.

[0056] At operation 620, an amplified linear frequency modulated pulse is modulated. In at least one example, modulating the amplified linear frequency modulated pulse generates a frequency-shifted copy of the amplified linear frequency modulated pulse offset by a frequency Δf. In at least one example, modulation is performed by an I / Q modulator. In at least one embodiment, the I / Q modulator receives the signal 1+e.j2πΔft The real components and the signal 1+e j2πΔft The imaginary component is used to modulate the amplified linear frequency modulated pulse. At operation 625, the modulated linear frequency modulated pulse is amplified and transmitted via one or more antennas.

[0057] Now for reference Figure 7 , Figure 7 A flowchart illustrating a method 700 for determining the velocity of an object detected by an FMCW radar system is shown. In at least some examples, method 700 is performed by an FMCW radar system (such as...) Figure 2 The FMCW radar system 200 is implemented, for example, at least in part by a radar transceiver IC (such as...). Figure 2 Radar transceiver IC 205 and / or Figure 3 The radar transceiver IC 300 is implemented.

[0058] At operation 705, the FMCW radar system calculates the first velocity estimate (v) of potential objects in the FMCW radar system's field of view based on the range Doppler array. est1 In one example, the range Doppler array is either a first range Doppler array corresponding to a first linear frequency modulated pulse sequence of a received radar frame or a second range Doppler array corresponding to a second linear frequency modulated pulse sequence of a received radar frame. In another example, the range Doppler array is the average or other relationship between or a combination of a first range Doppler array corresponding to a first linear frequency modulated pulse sequence of a received radar frame and a second range Doppler array corresponding to a second linear frequency modulated pulse sequence of a received radar frame. For example, the FMCW radar system calculates v according to method 400. est1 As mentioned above, this can be determined based on the position of the peaks in the distance-Doppler array corresponding to the potential object. As also mentioned above, the number of rows of peaks in the distance-Doppler array corresponds to the velocity of the potential object. In at least one example, v est1 It can be aliased (e.g., there may be a phase flip such that v est1 The error is the maximum measurable speed (v) max (integer multiples of )

[0059] In at least one example, the relative motion of the object with respect to the FMCW radar system across subsequent linear frequency modulated pulses in the received reflected linear frequency modulated pulse frame introduces a phase transition φ. d The phase transition is defined as follows:

[0060]

[0061] Where v is the velocity of the object, T cφ is the period of the linear frequency modulated (LFM) pulse, and λ is the wavelength corresponding to the start frequency of the LFM pulse. Since the phase between LFM pulses in a frame exhibits a linear series, FFT can be used to estimate the phase transition φ. d In one example, once the phase transition φ is estimated... d The velocity v can be estimated by inverting Equation 1. est1 In order to obtain the v given below est1 :

[0062]

[0063] In another example, v is estimated by performing a Doppler FFT as described above and finding the position of the peak corresponding to the object of interest in the resulting distance Doppler array. est1 .when At that time, and if the object's speed exceeds + / - 0.5 * v maxorig Then v est1 It may have approximately v maxorig An error that is an integer multiple of the value of v. maxorig This is when only the first linear frequency modulated pulse sequence (or only the second linear frequency modulated pulse sequence) is used without using v est2 The specific, detectable speed, as discussed in more detail below.

[0064] At operation 710, the FMCW radar system calculates a second velocity estimate (v) of the object based on the phase difference in the corresponding range Doppler arrays (e.g., a range Doppler array corresponding to the first linear frequency modulated pulse sequence and a range Doppler array corresponding to a second linear frequency modulated pulse sequence offset by Δf from the first linear frequency modulated pulse sequence). est2 As described above, in at least one example, a range-Doppler array is generated at least in part according to method 400. Once the phase difference is determined (e.g., by subtracting the phase of a peak of a range-Doppler array from the phase of the peak of the second range-Doppler array), the velocity estimate v can be estimated according to the following formula. est2 :

[0065]

[0066] Where Δφ is the phase difference (or the average of multiple phase differences) of the peaks in the range Doppler array (e.g., to illustrate an FMCW radar system with multiple transmit and / or receive antennas). And λ is the transmission wavelength of the FMCW radar system when the transmission is initiated (e.g., at operation 405 of method 400, see above reference). Figure 4 (Discussed).

[0067] At operation 715, the FMCW radar system is at least partially based on v est1 and v est2 Calculate the (v) of the object detected by the FMCW radar system true Actual or real speed. For example, the FMCW radar system can determine v using the following formula. true :

[0068] v true =v est1 +2nv maxorig (4)

[0069] Where n is the ambiguity in the estimated velocity calculation and is defined as n = (v est2 -v est1 ) / 2v maxorig The integer. In at least some examples, the calculated value of n can be rounded to the nearest integer before being used in Equation 4 to determine the actual speed of the object. In another example, v can be... maxorig Add various negative and positive (including 0) integer multiples to v est1 To form various sums, the one that is numerically closest to v. est2 The sum was chosen as v true .

[0070] Now for reference Figure 8 , Figure 8 A flowchart illustrating an illustrative method 800 for calibrating an FMCW radar system is shown. In at least some examples, method 800 is implemented by the FMCW radar system during its calibration operation mode. In at least one example, the FMCW radar system may be... Figure 2 The FMCW radar system 200, for example, consists at least in part of a radar transceiver IC (such as... Figure 2 Radar transceiver IC 205 and / or Figure 3 The radar transceiver IC 300 is implemented.

[0071] At operation 805, the FMCW radar system initiates the calibration process by transmitting a linear frequency modulated (LFM) pulse frame having a first LFM pulse sequence and a second LFM pulse sequence offset by Δf from the first LFM pulse sequence. The FMCW radar system can perform the transmission of the LFM pulse frame initiation in a manner substantially similar to operation 405 of method 400 discussed above, and its details will not be repeated here.

[0072] At operation 810, the FMCW radar system receives the reflected linear frequency modulated pulse frames and generates digital IF signals for each receiving antenna of the FMCW radar system. The FMCW radar system can perform the reception of reflected linear frequency modulated pulse frames and the generation of digital IF signals in a manner substantially similar to operation 410 of method 400 discussed above, and the details will not be repeated here.

[0073] At operation 815, the FMCW radar system demodulates the digital IF signal. The FMCW radar system can perform the demodulation of the digital IF signal in a manner substantially similar to operation 415 of method 400 discussed above, and the details will not be repeated here.

[0074] At operation 820, the FMCW radar system performs a range FFT on each result of operation 815 to generate a range array for each result of operation 815. The FMCW radar system can perform range array generation in a manner substantially similar to operation 420 of method 400 discussed above, and its details will not be repeated here.

[0075] At operation 825, the FMCW radar system performs a Doppler FFT on each range array to generate a range-Doppler array. The FMCW radar system can perform the generation of the range-Doppler array in a manner substantially similar to operation 425 of method 400 discussed above, and its details will not be repeated here.

[0076] At operation 830, the FMCW radar system calculates the phase difference of the object peak in the corresponding range-Doppler array. The FMCW radar system calculates the phase difference, for example, by subtracting the phase of the object peak in one range-Doppler array (e.g., a range-Doppler array corresponding to the linearly frequency-modulated pulses of the first linearly frequency-modulated pulse sequence) from the phase of the object peak in another range-Doppler array (e.g., a range-Doppler array corresponding to the linearly frequency-modulated pulses of the first linearly frequency-modulated pulse sequence offset by Δf). In at least one example, a search can be performed in each range-Doppler array to locate the object peak. Because the stationary object is known, the approximate location of one or more peaks corresponding to the object can be known. Therefore, a search can be performed in the approximate region of each range-Doppler array to locate the peak. Furthermore, if the object is large, there may be many peaks corresponding to that object. If there are multiple peaks, any one of them can be used.

[0077] At operation 835, the calculated phase difference can be stored by the FMCW radar system. In at least one example, the calculated phase difference can be referred to as the system phase offset for a specific receive channel, through which reflected linear frequency modulated pulse frames are received at operation 810. In at least one example, the FMCW radar system can use the system phase offset determined during calibration in method 800 when performing velocity calculations during normal operation of the FMCW radar system (e.g., such as when the FMCW radar system implements method 700).

[0078] For example, as part of the velocity calculation of an object, the system phase offset can be used as a reference. Figure 7 The method described by v est2 In the calculation, in at least one example, when the FMCW radar system includes multiple receive channels, the system phase offset of the receive channels is subtracted from the phase difference calculated for the receive channels before calculating the average phase difference. The system phase offset can also be used as part of the velocity calculation of the object, as in the reference... Figure 4 The method described above. For example, system phase offset can be applied to a corresponding range array generated before the interleaved range array.

[0079] Now for reference Figure 9 , Figure 9 A flowchart of an illustrative method 900 for calibrating an FMCW radar system is shown. In at least some examples, method 900 is implemented by the FMCW radar system during its normal operating mode. In various examples, method 900 may be performed periodically, upon command, and / or when the radar system is initialized. In at least one example, the FMCW radar system may be... Figure 2 The FMCW radar system 200, for example, consists at least in part of a radar transceiver IC (such as... Figure 2 Radar transceiver IC 205 and / or Figure 3 The radar transceiver IC 300 is implemented.

[0080] In at least one example, the calibration process begins at operation 905 by transmitting a linear frequency modulated (LFM) pulse frame by the radar transceiver IC. The LFM pulse frame may include a first LFM pulse sequence and a second LFM pulse sequence offset by Δf1 from the first LFM pulse sequence. Δf1 can use any suitable value. At operation 910, as the reflected LFM pulses are received, a digital IF signal is generated for each receive channel of the FMCW radar system.

[0081] At operation 915, the digital IF signal is demodulated, and at operation 920, the range Doppler array is calculated for each receive channel. When the range Doppler array is available, at operation 925, the phase difference of the object peak in the range Doppler array is calculated. For example, for each corresponding receive channel pair, the difference between the phase of the object peak in the range Doppler array generated by the first linear frequency modulated pulse sequence in the linear frequency modulated pulse frame and the phase of the object peak in the range Doppler array generated by the second linear frequency modulated pulse sequence in the linear frequency modulated pulse frame (e.g., subtracting a phase value from another phase value) is calculated.

[0082] At operation 930, the transmission of another linear frequency modulated (LFM) pulse frame is initiated by the radar transceiver IC. The LFM pulse frame may include a first LFM pulse sequence and a second LFM pulse sequence offset by Δf2 from the first LFM pulse sequence. Δf2 can use any suitable value. At operation 935, upon receiving the reflected LFM pulses, a digital IF signal is generated for each receive channel of the FMCW radar system.

[0083] At operation 940, the digital IF signal is demodulated, and at operation 945, the range Doppler array is calculated for each receive channel. When the range Doppler array is available, at operation 950, the phase difference of the object peak in the range Doppler array is calculated. For example, for each corresponding receive channel pair, the difference between the phase of the object peak in the range Doppler array generated by the first linear frequency modulated pulse sequence in the linear frequency modulated pulse frame and the phase of the object peak in the range Doppler array generated by the second linear frequency modulated pulse sequence in the linear frequency modulated pulse frame (e.g., subtracting a phase value from another phase value) is calculated.

[0084] At operation 955, the presence of a stationary object in the scene is then determined based on the phase difference between the two object peaks. For example, for an object peak appearing in two range Doppler arrays, the difference between each phase difference determined using frequency offset Δf1 for the peak and the respective phase difference determined using frequency offset Δf2 for the peak is compared with a threshold determined by the signal-to-noise ratio. If each difference is less than the threshold, the peak corresponds to a stationary object. Object peaks can be searched until a peak corresponding to a stationary object is found or all object peaks have been considered. If no stationary object exists, method 900 terminates at operation 960.

[0085] If a peak corresponding to a stationary object is found, then at operation 965, the system phase offset is calculated based on the phase difference determined using frequency offset Δf1 and the phase difference determined using frequency offset Δf2. For example, the corresponding phase differences are averaged to determine the system phase offset, one for each corresponding pair of receive channels. For example, as described above, the system phase offset is stored for use in velocity calculations performed during normal operation of the FMCW radar system.

[0086] In some examples, if multiple object peaks correspond to stationary objects, a system phase offset is also determined for these peaks. In such embodiments, the final system phase offset is determined by averaging the corresponding system phase offsets for all peaks.

[0087] In the case of a practical receiver, the first and second linear frequency modulated pulse sequences can have a frequency offset of Δf, such that the digital IF signal is between 0 and F. farthest It has the first sequence information at Δf to Δf+F farthest The second sequence is present. In the case of a composite receiver, the same method can be followed, or the first sequence can be made to correspond to 0 to F. farthest The second sequence corresponds to -Δf to -Δf+F. farthest In some examples, the latter approach saves bandwidth on the composite receiver (e.g., reduces implementation area and power consumption) by relying on the fact that the composite receiver provides natural image suppression (e.g., the +X Hz component does not affect the -X Hz frequency component or has an effect after the obvious image suppression provided by the composite receiver).

[0088] Although the operations of various methods of this disclosure have been discussed and labeled with reference numerals in the accompanying drawings, each of the various methods may include additional operations not listed herein, any one or more operations listed herein may include one or more sub-operations, any one or more operations listed herein may be omitted, and / or any one or more operations listed herein may be performed in an order different from the order presented herein (e.g., in reverse order, substantially simultaneously, overlapping, etc.), all of which are intended to fall within the scope of this disclosure.

[0089] In the preceding discussion, the terms “comprising” and “including” were used in an open-ended manner and should therefore be interpreted as meaning “including, but not limited to…”. Furthermore, the term “coupled” is intended to indicate an indirect or direct wired or wireless connection. Thus, if a first device, element, or component is coupled to a second device, element, or component, this coupling can be achieved through direct coupling or through indirect coupling via other devices, elements, or components and connections. Similarly, coupling between a device, element, or component and a second component or location can be achieved through direct connection or through indirect connection via other devices, elements, or components and / or couplings. A device “configured” to perform a task or function may be configured by the manufacturer at manufacturing time (e.g., programmed and / or hardwired) to perform that function and / or may be configured (or reconfigured) by the user after manufacturing to perform that function and / or other additional or alternative functions. Configuration can be achieved through firmware and / or software programming of the device, through the construction and / or layout of hardware components, and through interconnections of the device, or combinations thereof. Furthermore, it is said that circuitry or devices comprising certain components may alternatively be configured to be coupled to those components to form the described circuitry or device. For example, a structure described as including one or more semiconductor elements (such as transistors), one or more passive elements (such as resistors, capacitors and / or inductors) and / or one or more sources (such as voltage sources and / or current sources) may alternatively include only semiconductor elements within a single physical device (e.g., semiconductor dies and / or IC packages) and may be configured to be coupled to at least some passive elements and / or sources to form the described structure during or after manufacturing, for example by an end user and / or a third party.

[0090] Although certain components are described herein as having specific processing technologies (e.g., MOSFETs, NMOS, PMOS, etc.), these components can be replaced with those using other processing technologies (e.g., replacing MOSFETs with bipolar junction transistors (BJTs), NMOS with PMOS, etc., and vice versa), and the circuitry including the replaced components can be reconfigured to provide the desired functionality, at least partially similar to that available before the component replacement. Additionally, in the foregoing discussion, the phrase "ground voltage potential" is intended to include rack ground, earth ground, floating ground, virtual ground, digital ground, common ground, and / or any other form of grounding connection applicable to or suitable for the teachings of this disclosure. Unless otherwise stated, "about," "approximately," or "substantially" preceding a value means + / - 10% of that value.

[0091] The foregoing discussion is intended to illustrate the principles and various examples of this disclosure. Once the foregoing disclosure is fully understood, many variations and modifications will become apparent to those skilled in the art. This disclosure is intended to be construed as encompassing all such variations and modifications.

Claims

1. A radar system, comprising: Radar transceiver integrated circuits, also known as radar transceiver ICs, include: A timing engine that can be configured to generate one or more linear frequency modulated pulse control signals; A local oscillator coupled to the timing engine, the local oscillator being configured to: Receive the one or more linear frequency modulated pulse control signals; and A frame comprising a first linear frequency modulated pulse sequence is generated based on the one or more linear frequency modulated pulse control signals; A modulator coupled to the local oscillator, the modulator being configured to modulate the first linear frequency modulated (LFM) pulse sequence to generate a second LFM pulse sequence, such that the frame includes the first LFM pulse sequence and the second LFM pulse sequence offset by a first frequency value; and The processing circuit system is configured as follows: The first velocity estimate of the object within the field of view of the radar system is calculated based on the range Doppler array; A second velocity estimate of the object is calculated based on the difference between the phase of a peak in a first range-Doppler array for the first linear frequency modulated pulse sequence and the phase of a peak in a second range-Doppler array for the second linear frequency modulated pulse sequence; and Based on the first velocity estimate and the second velocity estimate, the final velocity estimate of the object is calculated. The first linear frequency modulated pulse sequence is associated with a first maximum measurable velocity limited by the minimum achievable linear frequency modulated pulse period, and the second linear frequency modulated pulse sequence is associated with a second maximum measurable velocity greater than the first maximum measurable velocity.

2. The radar system according to claim 1, wherein, The radar transceiver IC further includes a control module coupled to the timing engine and the modulator, wherein the control module is configured to: One or more parameter values ​​are transmitted to the timing engine to at least partially control the generation of the linear frequency modulated pulse control signal; and One or more signals are transmitted to the modulator to at least partially control the modulation of the first linear frequency modulated pulse sequence.

3. The radar system according to claim 1, wherein, The radar transceiver IC is configured as follows: A frame receiving reflected linear frequency modulated pulses, the reflected linear frequency modulated pulses comprising a first linear frequency modulated pulse sequence and a second linear frequency modulated pulse sequence reflected by an object within the field of view of the radar system; A digital intermediate frequency (IF) signal, i.e., a digital IF signal, is generated corresponding to the frame of the reflected linear frequency modulated pulse. as well as The digital IF signal is demodulated to obtain a first demodulated digital IF signal corresponding to the first linear frequency modulated pulse sequence and a second demodulated digital IF signal corresponding to the second linear frequency modulated pulse sequence, wherein, before demodulation, the first linear frequency modulated pulse sequence is offset from the second linear frequency modulated pulse sequence by the first frequency value in the digital IF signal.

4. The radar system of claim 3, wherein the range Doppler array on which the calculation of the first velocity estimate is based is one of the first range Doppler array, the second range Doppler array, and a relationship between the first range Doppler array and the second range Doppler array, and wherein the processing circuitry is configured to: Perform a distance Fast Fourier Transform (FFT) on the first demodulated digital IF signal and the second demodulated digital IF signal to generate a first distance array of the first demodulated digital IF signal and a second distance array of the second demodulated digital IF signal; and Perform a Doppler FFT on the first distance array and the second distance array to generate a first distance Doppler array corresponding to the first distance array and a second distance Doppler array corresponding to the second distance array.

5. The radar system according to claim 1, wherein, The radar system is configured to operate in calibration mode to determine the system phase offset between the receive channels of the radar transceiver IC, wherein the system phase offset is used to determine the velocity of an object within the field of view of the radar system.

6. The radar system according to claim 1, wherein, The first linear frequency modulated pulse sequence and the second linear frequency modulated pulse sequence are composed of Description, in which It is the first frequency value, where t represents time.

7. The radar system according to claim 1, wherein, The first linear frequency modulated pulse sequence and the second linear frequency modulated pulse sequence are transmitted using the same antenna of the radar system.

8. A method for determining an approximate velocity in a radar system, the method comprising: The radar system initiates a transmission channel via its radar transceiver with a first linear frequency modulated pulse sequence and a frequency offset from the first linear frequency modulated pulse sequence. The transmission of frames of linear frequency modulated pulses in the second linear frequency modulated pulse sequence, wherein the initiation includes: One or more linear frequency modulation pulse control signals are generated based on the linear frequency modulation pulse parameter values; A frame comprising the first linear frequency modulated pulse sequence is generated based on the one or more linear frequency modulated pulse control signals, wherein the first linear frequency modulated pulse sequence is associated with a first maximum measurable velocity limited by a minimum achievable linear frequency modulated pulse period; and The first linear frequency modulated pulse sequence is modulated to generate a second linear frequency modulated pulse sequence, such that the frame contains the first linear frequency modulated pulse sequence and an offset. The second linear frequency modulated pulse sequence, wherein the second linear frequency modulated pulse sequence is associated with a second maximum measurable velocity greater than the first maximum measurable velocity; The radar transceiver receives frames of reflected linear frequency modulated pulses via its receiving channel, the reflected linear frequency modulated pulses including a first linear frequency modulated pulse sequence and a second linear frequency modulated pulse sequence reflected by an object within the radar system's field of view. A digital intermediate frequency (IF) signal, i.e., a frame corresponding to the reflected linear frequency modulated pulse, is generated via the receiving channel. The digital IF signal is demodulated by a processor to form a first demodulated IF signal corresponding to the first linear frequency modulated pulse sequence and a second demodulated IF signal corresponding to the second linear frequency modulated pulse sequence; and The approximate speed is determined by the processor, at least in part, based on the first demodulated IF signal and the second demodulated IF signal.

9. The method according to claim 8, wherein, Determining the approximate velocity of an object within the field of view of the radar system, at least in part, based on the first demodulated IF signal and the second demodulated IF signal, includes: Perform a distance Fast Fourier Transform (FFT) on the first demodulated IF signal and the second demodulated IF signal to generate a first distance array corresponding to the first demodulated IF signal and a second distance array corresponding to the second demodulated IF signal; and Perform a Doppler FFT on the first and second distance arrays to generate a first and second distance Doppler arrays.

10. The method of claim 9, further comprising determining the approximate velocity of the object within the field of view of the radar system by using at least one of the first range Doppler array or the second range Doppler array: A first velocity estimate of the object within the field of view of the radar system is calculated based on at least one of the first range Doppler array or the second range Doppler array. Based on the phase difference with the peak corresponding to the object in the field of view of the radar system in the first range Doppler array and the second range Doppler array, a second velocity estimate of the object in the field of view of the radar system is calculated; as well as The approximate velocity of the object is calculated based on the first velocity estimate and the second velocity estimate.

11. The method of claim 10, further comprising operating in calibration mode to determine the system phase offset between the receive channels of the radar transceiver integrated circuit, i.e., the radar transceiver IC, wherein, The system phase offset is used to determine the approximate velocity of the object within the field of view of the radar system.

12. The method according to claim 8, wherein, The first linear frequency modulated pulse sequence and the second linear frequency modulated pulse sequence are composed of The description is given, where t represents time.

13. The method according to claim 8, wherein, Before demodulation, the second linear frequency modulated pulse sequence is offset from the first linear frequency modulated pulse sequence in the digital IF signal. .

14. A method for determining velocity in a radar system, the method comprising: A first velocity estimate is calculated via a processing element based on at least one range Doppler array, the range Doppler array being based on a first linearly modulated pulse sequence and a frequency offset from the first linearly modulated pulse sequence. The second linear frequency modulated pulse sequence is obtained by transmitting the linear frequency modulated pulse sequence frame, wherein the first linear frequency modulated pulse sequence and the second linear frequency modulated pulse sequence have been transmitted by the same radar transceiver; A second velocity estimate is calculated via the processing element based on the phase difference between a first peak in the at least one range-Doppler array and a second peak in at least one second range-Doppler array corresponding to the first peak, wherein the at least one second range-Doppler array is based on transmitting a pulse sequence having the first linear frequency modulated pulse sequence and a pulse sequence offset from the first linear frequency modulated pulse sequence. Obtained by the linear frequency modulated pulse frame of the second linear frequency modulated pulse sequence; and The speed is calculated by the processing element based on the first speed estimate and the second speed estimate. The first linear frequency modulated pulse sequence is associated with a first maximum measurable velocity limited by the minimum achievable linear frequency modulated pulse period, and the second linear frequency modulated pulse sequence is associated with a second maximum measurable velocity greater than the first maximum measurable velocity.

15. The method according to claim 14, wherein, By using an I / Q modulator The first linear frequency modulated pulse sequence is modulated to offset the second linear frequency modulated pulse sequence from the first linear frequency modulated pulse sequence, where t represents time.

16. The method according to claim 15, wherein, Modulate the first linear frequency modulated pulse sequence, such that according to The description of the first and second linear frequency modulated pulse sequences increases the maximum measurable velocity of the radar system by approximately The factors, among which It is the period of the first linear frequency modulated pulse sequence and the second linear frequency modulated pulse sequence, wherein , where s is the slope of the first linear frequency modulated pulse sequence.

17. The method of claim 14, wherein, Calculating the speed based on the first speed estimate and the second speed estimate includes: Determine the ambiguity associated with the first velocity estimate and the second velocity estimate; and The velocity of the object in the field of view of the radar system is calculated based on the first velocity estimate, the second velocity estimate, and the determined ambiguity.

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