On-site phase calibration

Abstract

A radar system includes a radar transceiver integrated circuit (IC) (302) and a processor (308) coupled to the radar transceiver IC (302). The radar transceiver IC (302) includes a chirp generator (314) configured to generate a plurality of chirp signals and a phase shifter (316) configured to cause signal phase shifts. The radar transceiver IC (302) is configured to transmit a chirp frame based on the plurality of chirp signals and generate a plurality of digital signals, each digital signal corresponding to a respective reflection received based on the plurality of chirp signals. The processor (308) is configured to control the phase shifter (316) to cause the signal phase shifts in a first subset of chirp signals of the plurality of chirp signals and determine phase shifts caused by the phase shifter (316) in the first subset of chirp signals based on the digital signals.

Description

Background Technology

[0001] A radar system emits electromagnetic wave signals, which are then reflected by objects in its path. By capturing the reflected signals, the radar system can assess the detected objects.

[0002] Beamforming is a signal processing technique used in conjunction with sensor arrays for directional signal transmission or reception. Spatial selectivity is achieved by using adaptive or fixed receive / transmit beam patterns. Doppler division multiple access (“DDMA”) is a signal processing technique also used in conjunction with sensor arrays to identify unique transmit array elements in the receive path.

[0003] Electronic devices employing beamforming or DDMA technologies include transmit (“TX”) phase shifters. These phase shifters exhibit device-dependent nonlinearities, resulting in a nonlinear mapping between the desired programmed phase and the actual programmed phase. To overcome this nonlinearity, phase shifter calibration can be performed at the factory during the manufacturing of electronic devices incorporating phase shifters. However, factory calibration may be insufficient to capture the effects of temperature / aging over the device's lifespan.

[0004] Alternatively, using an internal loopback procedure, test signals generated in the transmit channels and provided to the receive channels via the internal loopback path can be used to determine the phase response of each transmit channel. The phase response can be used to adjust the transmit signal to calibrate any offset phase shift. However, due to on-board wiring mismatches, this on-chip loopback calibration may not be suitable for calibrating phase shifts. Summary of the Invention

[0005] In one aspect, a radar system includes a radar transceiver integrated circuit (IC) and a processor coupled to the radar transceiver IC. The radar transceiver IC includes a linear frequency modulation (LFM) generator configured to generate a plurality of chirp signals and a phase shifter configured to cause a phase shift in the signals. The radar transceiver IC is configured to transmit LFM frames based on the plurality of LFM signals and generate a plurality of digital signals, each digital signal corresponding to a corresponding reflection received based on the plurality of LFM signals. The processor is configured to control the phase shifter to cause a phase shift in the signals within a first subset of the plurality of LFM signals and to determine the phase shift caused by the phase shifter in the first subset of the LFM signals based on the digital signals.

[0006] In another aspect, a method includes: generating a plurality of linear frequency modulated (LFM) signals; inducing a phase shift in a first subset of the plurality of LFM signals; and initiating the transmission of a LFM frame based on the plurality of LFM signals. The method further includes: generating a plurality of digital signals in response to reflected LFM of the plurality of LFM signals received in the LFM frame; and determining, based on the digital signals, a phase shift induced by a phase shifter in the first subset of LFM signals. Attached Figure Description

[0007] In the diagram:

[0008] Figure 1 It is a signal graph of a linear frequency modulated signal based on the magnitude-time plot of the example.

[0009] Figure 2 It is based on examples Figure 1 The signal graph of a linear frequency modulated signal on a frequency-time plot.

[0010] Figure 3 This is a block diagram of an FMCW radar system based on an example.

[0011] Figure 4 This is a block diagram based on another example of an FMCW radar system.

[0012] Figure 5 It is an instance of a linear frequency modulation transmission frame based on the instance.

[0013] Figure 6 It is an instance of the modulus / sample matrix based on the instance.

[0014] Figure 7 This is a diagram illustrating an example of a 2D-FFT matrix based on an instance.

[0015] Figure 8 This is a flowchart illustrating a method for phase shift calibration based on an example.

[0016] Figure 9 It is an instance of a linear frequency modulation transmission frame based on the instance.

[0017] Figure 10 It is an instance of the modulus / sample grouping matrix based on the instance.

[0018] Figure 11 This is a diagram illustrating the example based on... Figure 10 An example of a 2D-FFT matrix of a matrix.

[0019] Figure 12 This is an instance of an indexing scheme for a Doppler index of a 2D-FFT with an odd number of rows, based on the example.

[0020] Figure 13 This is an instance of an indexing scheme for a Doppler index of a 2D-FFT with an even number of rows, based on the instance. Detailed Implementation

[0021] Millimeter wave (mmWave) is a special type of radar technology that uses short-wavelength electromagnetic waves. In a type of mmWave technology called frequency-modulated continuous wave (FMCW), FMCW radar continuously transmits frequency-modulated signals to measure range, angle, and velocity. In the radar system, electromagnetic signals are emitted and reflected by objects in their path. In the signals used in FMCW radar, the frequency increases linearly with time. This type of signal is also called linear frequency modulation (LFM). Figure 1 Figure 100 illustrates a representative linear frequency modulated signal 102 with a magnitude (amplitude) that varies over time. Figure 2 A diagram illustrating frequencies that vary over time. Figure 1 The linear frequency modulated signal 102. The linear frequency modulated signal 102 is composed of a starting frequency (f). c 200, Bandwidth (B) 202, and Duration (T) c )204 characterization. The slope of the linear frequency modulated signal and the rate of change of the capture frequency.

[0022] Figure 3 The diagram illustrates a block diagram of an FMCW radar system 300 configured to transmit a linear frequency modulated signal (e.g., linear frequency modulated signal 102) and capture signals reflected by objects in its path. As shown, the radar system 300 includes a radar transceiver integrated circuit (IC) 302 and a processing unit 304. The processing unit 304 is coupled to the radar transceiver IC 302 via a serial interface 306 to send data to and receive data from the radar transceiver IC 302. In one example, the serial interface 306 may be a high-speed serial interface, such as a low-voltage differential signaling (LVDS) interface. In another example, the serial interface may be a lower-speed serial peripheral interface (SPI).

[0023] Transceiver IC 302 includes functionality for generating multiple digital intermediate frequency (IF) signals (alternatively referred to as de-linear frequency modulation signals, beat signals, or raw radar signals) from reflected linear frequency modulation. Furthermore, transceiver IC 302 may include functionality for performing a portion of signal processing on the radar signals received therein and providing the results of this signal processing to processing unit 304 via serial interface 306. In one example, radar transceiver IC 302 performs a range fast Fourier transform (FFT) on each radar frame. In another example, radar transceiver IC 302 performs a range FFT and a Doppler FFT on each radar frame.

[0024] Processing unit 304 includes functionality for processing data received from radar transceiver IC 302 to perform any remaining signal processing, thereby determining, for example, the distance, velocity, position, and / or angle of any detected object. Processing unit 304 may also include functionality for performing post-processing of information about the detected object, such as tracking the object, determining the rate and direction of movement, etc. Processing unit 304 can perform phase shifter calibration according to any example of calibration described herein. Depending on the processing throughput requirements of the application using the radar data, processing unit 304 may include any suitable processor or combination of processors (illustrated as processor 308). For example, processing unit 304 may include a digital signal processor (DSP), a microcontroller (MCU), a SoC combining DSP and MCU processing, or a floating-point gate array (FPGA) and a DSP. Processing unit 304 also includes computer-readable storage memory 310 for storing phase calibration data.

[0025] The transceiver IC 302 includes a local oscillator 312, a ramp generation component 314, a phase shifter 316, a transmit antenna 318, a receive antenna 320, a mixer 322, an analog-to-digital converter (ADC) 324, and a digital signal processor (DSP) 326. Although Figure 3 The diagram illustrates a single representative TX chain and RX chain, but in some instances, multiple chains can be used to support multiple TX and RX antennas.

[0026] Local oscillator 312 is operable to provide a reference signal (e.g., timing and / or reference frequency) to ramp generation assembly 314. In some instances, local oscillator 312 itself can provide a frequency ramp centered at a lower frequency, which ramp generation assembly 314 can then convert to a transmission frequency. Ramp generation assembly 314 is arranged to provide the resulting ramp signal to phase shifter 316 via line 330. If phase shifting is required (e.g., in beamforming or DDMA radar technology), then phase shifter 316 can be controlled by processing unit 304 to apply phase shifting to the ramp signal generated on line 330. Phase shifter 316 can change the phase of the ramp signal or allow the ramp signal to be transmitted to transmit antenna 318 via line 332 without alteration. Based on the prior calibration of the radar system 300, the processing unit 304 can access the phase calibration value (e.g., from the storage device 310) of the desired specific phase shift value, so that the phase shifter 316 is applied to the signal transmitted by the TX antenna 318 to achieve the desired phase shift, and the transmitting antenna 318 is operable to transmit those signals over the air.

[0027] In some instances, a series of linearly frequency-modulated (LFM) or linearly frequency-modulated continuous wave (CW) signals are generated at the ramp generation component 314 based on input from a local oscillator 312, the input being transmitted over the air by a transmitting antenna 318. The transmitted CW signals are reflected from objects within the range and coverage of the radar beam.

[0028] The receiving antenna 320 is operable to receive signals over the air and provide the received signals to the mixer 322 on line 334. Furthermore, the mixer 322 can also receive signals from the ramp generation component 314 on line 332, mix the signals from the receiving antenna 320 with the signals from the ramp generation component 314, and send the resulting mixed signal to the ADC 324. The ADC 324 is operable to convert analog signals into digital signals. The DSP 326 receives signals from the ADC 324 via line 336 and is operable to process digital signals.

[0029] In some instances, a linearly frequency-modulated signal transmitted from transmit antenna 318 is reflected from the object, and the reflected signal is received at antenna 320 and passed to mixer 322. Mixer 322 mixes the received signal with a ramp at the transmit frequency to generate an analog intermediate frequency (IF) signal on line 338. ADC 324 samples the analog IF signal to generate a digital IF signal on line 336. The digital IF signal is then processed and analyzed by DSP 326 to determine the velocity and range of the object within the beam.

[0030] Figure 3 The radar system 300 can be used, for example, in DDMA radar technology, where the same transmitter can transmit signals with and without phase shift. In a beamforming example, it provides... Figure 4 . Figure 4 Includes the above-mentioned Figure 3 The radar system 400, described with similar components and illustrated, has multiple transmission paths: one path includes a phase shifter 316, a TX antenna 318, and line 332, and another path includes an additional TX antenna 402 coupled to a ramp generation assembly 314 via a line 404 without a phase shifter. Alternatively, the phase shifter (not illustrated) may also be coupled to the TX antenna 402 and may be either inactive or activated to apply zero phase shift in transmission sequences where no phase shift occurs in the transmitted signal. Furthermore, DDMA radar technology may also be used. Figure 4 The radar system 400 is used to execute this.

[0031] Determining the range of objects within the beam involves performing an FFT on the digitized samples, where the frequency of the peak in the range FFT directly corresponds to the range of various objects in the scene. While the frequency of the peak in the range FFT directly corresponds to the object's range, the phase of this peak is extremely sensitive to small changes in the object's range. For example, a quarter-wavelength change in object position (≈1mm at 77GHz) translates to a complete 180-degree phase reversal. This phase sensitivity is the basis for the radar's ability to estimate the frequency of vibrating objects. It also forms the basis for velocity estimation. To distinguish the scene in the velocity dimension, the radar can emit a time-equally spaced linear frequency modulated sequence 500, such as frame 502. Figure 5 The diagram illustrates this. Each frame 502 may contain N linear frequency modulateds, which may be equally spaced (as shown) or asymmetrically spaced.

[0032] Figure 6 The diagram illustrates matrix 600, which shows the ADC samples corresponding to N linear frequency modulated (LFM) samples in a frame arranged according to LFM index 602 and ADC sample index 604. In the signal processing chain, a device such as DSP 326 performs a range FFT on the digitized samples corresponding to each LFM 500, wherein the output is stored as consecutive rows in a matrix. Each row of matrix 600 contains ADC samples from the corresponding LFM 500. Consecutive rows contain data spanning the LFM 500. A Doppler FFT is then performed across the columns of matrix 600 to produce a 2D-FFT of the digitized samples corresponding to frame 502.

[0033] Figure 7 The diagram illustrates a 2D-FFT matrix 700 arranged according to Doppler index 702 and range index 704, based on an example. Peaks 706, 708, 710, and 712 in the 2D-FFT matrix 700 correspond to detected objects. The position of each peak 706, 708, 710, and 712 in the 2D-FFT matrix corresponds to the range and Doppler (relative to radar) of the object. The 2D-FFT matrix 700 may be referred to as a "range-Doppler" matrix. Furthermore, each cell in the 2D-FFT matrix 700 may be referred to as a "range-Doppler cell".

[0034] Figure 8 The diagram illustrates a flowchart of phase shifter calibration technique 800 according to an example. The processor (e.g., Figure 3 , 3The processing unit 304 of b can be programmed to control the phase shifter to apply a specific phase shift to the ramp signal to be used in the radar system. In an ideal system, the phase shift implemented in the system will match or be substantially equal to the desired phase shift. However, depending on factors such as device characteristics and other non-ideal parameters for a particular phase shifter, the programmed phase may not be the actual phase applied to the signal. Therefore, the processor can be programmed to find a calibration value that has been calibrated at the factory for use with a particular phase shifter to modify the programmed phase so that the phase shifter applies the desired phase to the signal. Thus, the calibration of the phase shifter is a factor in achieving the desired phase signal modification. However, the phase shifter may change over time, making earlier calibration values ​​outdated. In this case, the phase shifter may drift and begin to apply an incorrect phase to the signal again. Thus, the phase shifter may need to be recalibrated. In addition, routing mismatches between multiple transmitter paths can further lead to a difference between the actual phase shift and the phase shift expected to be applied to the signal. Technology 800 provides a method for calibrating a phase shifter, regardless of whether the radar system incorporating the phase shifter is calibrated at its manufacturing facility or off-site.

[0035] Technique 800 begins at start 802 with the transmission of linear frequency modulation (LFM) frames with alternating phase shifts. While a ramp generator, for example, in ramp generation assembly 314 is controlled to produce a series of similar LFMs, a first subset of the series (e.g., every other LFM in the series) is modified with a first phase shift before being transmitted by the TX antenna, while a second subset of the series (e.g., LFMs not belonging to the first subset) may not be modified or may be modified with a second phase shift before being transmitted. Reference Figure 9 The example illustrates an alternating linear frequency modulation (LFM) frame 900. In LFM frame 900, odd-numbered LFMs 901, 903, 905 (e.g., first, third, n-1, etc.) are transmitted without a phase shifter applying a desired or expected phase shift to the ramp signal from the ramp generator. Alternatively, the phase shifter can be controlled to apply zero phase shift to the odd-numbered LFMs 901, 903, 905 before they are transmitted. However, for even-numbered LFMs 902, 904, 906 (e.g., second, fourth, n, etc.), the phase shifter modifies the ramp signal to induce a desired value (ΔΦ) of phase shift for transmission. setting In this way, non-phase-shifted linear frequency modulation (NFM) and phase-shifted linear frequency modulation (FM) are interleaved. The desired phase shift value (ΔΦ) setting ) is the value to be calibrated. In alternative examples, odd-numbered linear frequency modulations 901, 903, and 905 can be transmitted with phase-shifted linear frequency modulation, while even-numbered linear frequency modulations 902, 904, and 906 can be transmitted without applying a phase shift to them.

[0036] When the actual phase difference between odd and even linear frequency modulations 901 and 906 is transmitted, and the desired phase shift value (ΔΦ) is... setting When there is a mismatch, technique 800 can be used to calibrate the phase shifter. Each desired phase shift value to be used with a particular phase shifter can be calibrated individually because the phase shifter may not exhibit similar effects for every phase. However, interpolation by finding the uncalibrated value between a pair of calibrated values ​​can be used to approximate the effect of the phase shifter on the uncalibrated value.

[0037] Return to reference Figure 8 When a reflected signal is received from reflected linear frequency modulation (LFM), a digital IF signal 804 is generated. Based on a set of received signals from unshifted LFM (e.g., odd LFM 901, 903, 905) and a set of received signals from shifted LFM (e.g., even LFM 902, 904, 906), the digital IF signal is separated 806 and grouped together into corresponding subframes. Figure 10 The diagram illustrates matrices 1000 and 1002 created from separate digital IF signals. Matrix 1000 contains odd-numbered linear frequency modulators, such as linear frequency modulator 1, linear frequency modulator 3, ..., linear frequency modulator N-1, while matrix 1002 contains even-numbered linear frequency modulators, such as linear frequency modulator 2, linear frequency modulator 4, ..., linear frequency modulator N.

[0038] Return to reference Figure 8 An 808-range FFT is performed on the digital IF signals in each matrix 1000 and 1002 to generate a range array for each digital IF signal. Then, an 810-Doppler FFT is performed on each odd or even range array to generate a pair of range-Doppler arrays. Figure 11 The diagram illustrates that an odd-numbered Doppler FFT 1100 with reference peaks 1102, 1104, 1106, and 1108 in various range-Doppler cells is generated based on an odd-numbered linear frequency modulation matrix 1000, and an even-numbered Doppler FFT 1110 with reference peaks 1112, 1114, 1116, and 1118 in various range-Doppler cells is generated based on an even-numbered matrix 1002.

[0039] refer to Figure 8 and 11A detection algorithm is run to identify detected objects in the 812 2D-FFT matrices 1100 and 1110. Object identification involves converting the complex 2D-FFT matrices 1100 and 1110 into real positive numbers by taking the absolute values ​​of the matrix elements. A detection algorithm (e.g., constant false alarm rate (CFAR) detection) is then run on the resulting matrices to identify peaks 1102 and 1112. Peaks 1102 and 1112 are subsequently identified as detected objects. In some instances, the sum of the absolute values ​​of corresponding elements of the 2D-FFT matrices spanning the RX antenna is calculated, and the resulting matrix is ​​then used to identify detected objects. It is also possible to sum the absolute values ​​of corresponding elements of the 2D-FFT matrix pairs (corresponding to odd and even linear frequency modulation for a particular RX antenna) and use this sum for detection.

[0040] Once the cell corresponding to the detected object in the 2D-FFT matrices 1100 and 1110 is identified, technique 800 compares the corresponding phases of the range-Doppler cells between the two 2D-FFT matrices 1100 and 1110. For the i-th detected object, the difference or shift between the phases of the corresponding cell pairs (a cell from each 2D-FFT 1100, 1110 at the same range index and Doppler index) is ΔΦ. i During or between the application of a linear frequency modulated (LFM) pulse and subsequent LFM pulses, the movement of the object causes a velocity-induced phase shift independent of the phase shift caused by the phase shifter, simply because the object moves between two LFM pulses. For an object in a non-zero line Doppler cell, 816 phases can be corrected to compensate for the velocity-induced phase shift. This correction is calculated as:

[0041]

[0042] Where N dappler It is the length of the Doppler dimension of the 2D-FFT matrix 1100, 1110, and k doppler_bin It is the Doppler index of the range-Doppler unit corresponding to the target. For each ΔΦ i The corrected value is expressed as ΔΦ i,corr .

[0043] Figure 12 A diagram illustrating the Doppler index (k) used for a 2D-FFT with 1202 rows of odd-numbered rows (1204). doppler_bin The index scheme is 1200. As illustrated in the diagram, the first row is 1206 (k doppler_bin =0) are arranged as the central vertical rows. The rows above the zero Doppler row 1206 (e.g., rows 1208 and 1210) correspond to positive Doppler (k=0). doppler_bin >0), while the rows below zero Doppler row 1206 (e.g., rows 1212 and 1214) correspond to negative Doppler (k).doppler_bin <0).

[0044] Figure 13 A diagram illustrating the Doppler index (k) used for 2D-FFT 1302 with even-numbered rows (1304). doppler_bin The indexing scheme is 1300. As illustrated, no row 1304 is the center row because matrix 1302 has an even number of rows 1304. In this case, the first row 1306, corresponding to the top row of the lower half of row 1304, is arranged as the center vertical row (k). doppler_bin =0). Rows above zero Doppler row 1306 (e.g., rows 1308 and 1310) correspond to positive Doppler (k=0). doppler_bin >0), while the rows below zero Doppler row 1306 (e.g., rows 1312 and 1314) correspond to negative Doppler (k). doppler_bin <0).

[0045] Refer again Figure 8 In some instances, the 818 outlier detection algorithm is executed to detect and remove the set {ΔΦ}. 1，corr , ΔΦ 2,corr ,Φ 3，coor Outliers in ...}. For example, outliers can be identified by their signal-to-noise ratio, by estimates of outliers falling outside the expected range, etc. The average of all identified phase differences (with or without outliers removed) is calculated as follows:

[0046]

[0047] Where ∑ΔΦ i，corr It is the sum of all corrected values ​​and N objects This is the number of corrected values.

[0048] ΔΦ ave Indicates application to ΔΦ setting The expected setting is an estimate of the true or actual phase shift. In one instance, if ΔΦ ave Value and ΔΦ setting If the difference is outside the required tolerance 822, then technique 800 can return to the launch step at 802 and use the modified ΔΦ. setting The value will be retried. For example, if ΔΦ is determined... ave Inserting too much phase shift into the signal can reduce ΔΦ setting The value is reduced by the difference in additional phase shift and processed through steps of technique 800 for another iteration. Modification of ΔΦ can be performed. setting Repeated iterations of the value until ΔΦ ave The value falls within the required tolerance limit.

[0049] ΔΦ ave and ΔΦsetting Both can be stored in a computer-readable storage medium, such as a lookup table. In this way, a lookup table is created that lists the phase shifter settings ΔΦ. setting And its application of phase shift ΔΦ ave For ΔΦ setting Other values, repeatable technique 800. The table need not be exhaustive, but can be configured to contain only phase shifts near the phase shift to be applied to a particular application (e.g., a TX multiplexing scheme implementing, for example, DDMA contains a specific set of phase shifts). Each application then looks up the table and identifies the ΔΦ closest to its desired setting. ave The entry, and set the phase shifter to the corresponding ΔΦ. setting Alternatively, the values ​​can be interpolated, as described above. If multiple RX antennas exist, technique 800 can be repeated for a pair of 2D-FFTs generated at each RX antenna, and the estimated phase difference can be included in the averaging calculation.

[0050] Radar systems 300 and 400 can utilize technique 800 to calibrate their phase shifters 316 in the field after systems 300 and 400 have left their manufacturing facilities. Technique 800 can be configured to operate on a time-based schedule or manually. Furthermore, technique 800 does not require radar systems 300 and 400 to remain stationary. Therefore, the calibration of the phase shifters 316 of radar systems 300 and 400 by performing technique 800 can be performed while radar systems 300 and 400 are in motion (e.g., when mounted on a moving vehicle). As described herein, it is useful to create individual 2D-FFTs based on whether the received signal corresponds to a phase-shifted linear frequency modulated (LFM) transmission or a non-phase-shifted LFM transmission for generating 2D-FFTs, where the peaks detected in each 2D-FFT correspond to the same range-Doppler cell location. For a fixed field of view, a set of linear frequency modulated (LFM) signals without phase shift can be transmitted, followed by phase-shifted LFM signals or vice versa, because the field of view does not change between signal transmission types. However, for a moving field of view (e.g., in a radar system, where objects in the field of view, or where both change position relative to each other), interleaving the LFM signals when one type of LFM transmission follows another type of LFM transmission in time can reduce the field of view difference between the resulting 2D-FFTs.

[0051] The foregoing description of various preferred embodiments of the invention has been presented for illustrative and descriptive purposes. It is not exhaustive and does not limit the invention to the precise forms described, and it will be apparent from the foregoing teachings that many modifications and variations are possible. As described above, embodiments were chosen and described in order to best illustrate the principles of the invention and its practical application, thereby enabling those skilled in the art to best utilize the invention in various embodiments and with various modifications suitable for the intended particular use. The scope of the invention is defined by the appended claims.

Claims

1. A radar system comprising: Radar transceiver integrated circuit (IC), which includes: A linear frequency modulation (LFM) generator configured to generate multiple LFM signals; and A phase shifter coupled to the linear frequency modulation generator to receive the plurality of linear frequency modulation signals and configured to induce a phase shift in one or more of the plurality of linear frequency modulation signals; and a processor, which is coupled to the radar transceiver IC and configured to: The phase shifter is controlled to induce a target phase shift in a first subset of the plurality of linear frequency modulated signals; In response to receiving a reflected linear frequency modulated signal from the plurality of linear frequency modulated signals, a plurality of digital signals are generated; Process the plurality of digital signals to generate a first range-Doppler array and a second range-Doppler array; Identify one or more objects in the first range-Doppler array and the second range-Doppler array, each of the identified one or more objects being represented in a corresponding cell of the first range-Doppler array and the second range-Doppler array; For each of the one or more objects identified in the first range-Doppler array and the second range-Doppler array, the phase of the object represented in the first range-Doppler array is compared with the phase of the object represented in the second range-Doppler array to compensate for the phase shift caused by the object's velocity; and The actual phase shift in the first linear frequency modulated signal subset caused by the target phase shift induced by the phase shifter in the first linear frequency modulated signal subset is determined based on the comparison operation.

2. The radar system of claim 1, wherein the plurality of linear frequency modulated signals further comprises a second subset of linear frequency modulated signals; and The processor is further configured to control the phase shifter not to cause a phase shift in each linear frequency modulation signal in the second linear frequency modulation signal subset.

3. The radar system of claim 1, wherein the plurality of linear frequency modulated signals further comprises a second subset of linear frequency modulated signals; and The linear frequency modulation (LFM) signals in the first LFM signal subset are interleaved with the LFM signals in the second LFM signal subset.

4. The radar system of claim 1, wherein the plurality of linear frequency modulated signals further comprises a second subset of linear frequency modulated signals; and The processor is further configured to: A first matrix is ​​generated based on a first subset of the plurality of digital signals, wherein the first subset of digital signals corresponds to one or more reflections received based on the first linear frequency modulated signal subset; and A second matrix is ​​generated based on a second subset of the plurality of digital signals, the second subset of digital signals corresponding to one or more reflections received based on the second linear frequency modulated signal subset.

5. The radar system of claim 4, wherein the processor is further configured to: Perform a range Fast Fourier Transform (FFT) on each digital signal in the first matrix to generate a first range array for each digital signal in the first matrix; Perform a range FFT on each digital signal in the second matrix to generate a second range array for each digital signal in the second matrix; Perform a Doppler FFT on the columns in the first range array to generate the first range-Doppler array; and Perform a Doppler FFT on the columns in the second range array to produce the second range-Doppler array.

6. The radar system of claim 5, wherein the processor is further configured to: Identify one or more peaks in each of the first range-Doppler array and the second range-Doppler array, wherein the one or more peaks correspond to the corresponding range-Doppler element and to one or more objects in the field of view of the radar system; Identify one or more phase shifts, each phase shift corresponding to a phase shift between a corresponding peak in the first range-Doppler array and its corresponding peak in the second range-Doppler array; and The actual phase shift in the first linear frequency modulated signal subset is determined based on one or more identified phase shifts.

7. The radar system of claim 6, wherein the processor is further configured to calculate the average phase shift of the identified one or more phase shifts; and The processor, when configured to determine the actual phase shift in the first linear frequency modulated signal subset, is configured to determine the actual phase shift in the first linear frequency modulated signal subset based on the average phase shift.

8. The radar system of claim 6, wherein the processor is further configured to store the determined actual phase shift in the first linear frequency modulated signal subset in a computer-readable storage memory.

9. The radar system of claim 6, wherein the plurality of linear frequency modulated signals are a first plurality of linear frequency modulated signals, and the processor is further configured to determine whether the difference between the target phase shift and the determined actual phase shift is within a tolerance value; and When the difference is not within the tolerance value: Transmit a second or more linear frequency modulated signals; Control the phase shifter to cause a modified phase shift in a first subset of linear frequency modulated signals within the second plurality of linear frequency modulated signals, the modified phase shift being based on a determined actual phase shift in the first subset of linear frequency modulated signals; and The iterative phase shift caused by the modified phase shift of the phase shifter in the first linear frequency modulation signal subset of the second plurality of linear frequency modulation signals is determined based on the digital signal, the digital signal corresponding to the reflection received based on the second plurality of linear frequency modulation signals.

10. The radar system of claim 7, wherein the processor is further configured to remove outliers of one or more phase shifts before calculating the average phase shift.

11. A method comprising: Multiple linear frequency modulated signals are generated, including a first subset of linear frequency modulated signals and a second subset of linear frequency modulated signals; The phase shifter causes a target phase shift in the first linear frequency modulated signal subset; Initiate the transmission of the plurality of linear frequency modulated signals; Multiple digital signals are generated in response to the received multiple linear frequency modulated signals via reflected linear frequency modulation; Process the plurality of digital signals to generate a first range-Doppler array and a second range-Doppler array; Identify one or more objects in the first range-Doppler array and the second range-Doppler array, each of the identified one or more objects being represented in a corresponding cell of the first range-Doppler array and the second range-Doppler array; For each of the one or more objects identified in the first range-Doppler array and the second range-Doppler array, the phase of the object represented in the first range-Doppler array is compared with the phase of the object represented in the second range-Doppler array to compensate for the phase shift caused by the velocity of the object; and Based on the result of the comparison operation, the actual phase shift in the first linear frequency modulated signal subset caused by the target phase shift induced by the phase shifter in the first linear frequency modulated signal subset is determined.

12. The method of claim 11, wherein each linear frequency modulation signal in the second linear frequency modulation signal subset is free from phase shift caused by the phase shifter.

13. The method of claim 12, further comprising interleaving the linear frequency modulated signals in the first linear frequency modulated signal subset with the linear frequency modulated signals in the second linear frequency modulated signal subset.

14. The method of claim 12, wherein the process further comprises: A first matrix is ​​generated based on a first subset of the plurality of digital signals, the first subset of digital signals corresponding to one or more reflections received based on the first subset of the plurality of linear frequency modulated signals. and A second matrix is ​​generated based on a second subset of the plurality of digital signals, the second subset of digital signals corresponding to one or more reflections received based on the second linear frequency modulated signal subset.

15. The method of claim 14, wherein the process further comprises: Perform a range Fast Fourier Transform (FFT) on each digital signal in the first matrix to generate a first range array of each digital signal in the first matrix; Perform a range Fast Fourier Transform (FFT) on each digital signal in the second matrix to generate a second range array for each digital signal in the second matrix; Perform a Doppler FFT on the columns in the first range array to generate the first range-Doppler array; and Perform a Doppler FFT on the columns in the second range array to produce the second range-Doppler array.

16. The method of claim 15, wherein the process further comprises: Identify one or more peaks in each of the first range-Doppler array and the second range-Doppler array, wherein the one or more peaks correspond to a corresponding range-Doppler cell and to the one or more objects in the field of view; Identify one or more phase shifts, each phase shift corresponding to a corresponding peak in the first range-Doppler array and its corresponding peak in the second range-Doppler array; and The actual phase shift in the first subset of linear frequency modulated signals among the plurality of linear frequency modulated signals is determined based on one or more identified phase shifts.

17. The method of claim 16, wherein the method further comprises calculating the average phase shift of the identified one or more phase shifts; and Determining the actual phase shift of the phase shifter in the first subset of the plurality of linear frequency modulated signals includes: The actual phase shift in the first linear frequency modulated signal subset among the plurality of linear frequency modulated signals is determined based on the average phase shift.

18. The method of claim 16, further comprising storing the determined actual phase shift caused by the first linear frequency modulated signal subset in a computer-readable storage memory.

19. The method of claim 16, wherein the plurality of linear frequency modulated signals are a first plurality of linear frequency modulated signals, and the method further comprises determining whether the difference between the target phase shift and the determined actual phase shift is within a tolerance value; and When the difference is not within the tolerance value: Transmit a second or more linear frequency modulated signals; Control the phase shifter to cause a modified phase shift in a first subset of linear frequency modulated signals within the second plurality of linear frequency modulated signals, the modified phase shift being based on the determined actual phase shift in the first subset of linear frequency modulated signals within the first plurality of linear frequency modulated signals; and The iterative phase shift caused by the modified phase shift of the phase shifter in the first linear frequency modulation signal subset of the second plurality of linear frequency modulation signals is determined based on the digital signal, the digital signal corresponding to the reflection received based on the second plurality of linear frequency modulation signals.

20. The method of claim 17, further comprising removing outliers of one or more phase shifts identified prior to calculating the average phase shift.

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