Radar signal processing system and method

Abstract

The present invention provides a radar signal processing system and method for extracting the Doppler frequency from a sampled digital input signal emitted by a frequency-modulated continuous wave (FMCW) radar. The system comprises a transmitting module, a variation module, an extraction module, and an adjustment module. The transmitting module is configured to repeatedly transmit a radar signal having a unique frequency variation and pulse repetition interval; the variation module is configured to change the frequency variation or pulse repetition interval of the radar signal transmitted by the transmitting module; the extraction module is configured to extract an interference signal from the varying radar signal when the radar signal with the varying frequency or pulse repetition interval interferes with another radar signal; and the adjustment module is configured to adjust the radar signal to reduce the extracted interference signal. The system and method provided by this disclosure can reduce interference signals in vehicle-to-vehicle radar signals.

Description

Technical Field

[0001] The present disclosure relates to a radar signal processing system and method, and more particularly, to a system and method for processing radar signals by using a frequency modulation continuous wave (FMCW) that can modulate the radar signal by radiating a frequency to detect the distance and speed of an object, thereby reducing interference signals from vehicle-to-vehicle radar signals in a vehicle. Background Art

[0002] Frequency modulated continuous wave (FMCW) radar transmits a linear frequency modulation signal to receive the transmitted radar signal reflected by the object to be detected, and detects the distance and speed of the object based on the frequency difference between the received signal and the transmitted signal.

[0003] Recently, for the sake of driving safety, more and more vehicles are equipped with radars that provide information by recognizing the surrounding environment. Among these radars, FMCW radars are commonly used in vehicles. When FMCW radars detect other vehicles and objects, mutual interference can occur, resulting in missing targets or false detections of incorrect targets.

[0004] The FMCW radar installed in conventional vehicles to detect other vehicles and objects is a sensor that radiates electromagnetic waves and identifies objects by using the characteristics of the received electromagnetic wave signal. However, due to the interference phenomenon introduced into another radar signal, the original signal of the target is distorted, which in turn causes its performance to degrade.

[0005] The matters described in the background art are only for improving the understanding of the background art of the present disclosure and should not be regarded as an admission that they correspond to the prior art known to those skilled in the art. Summary of the Invention

[0006] The present disclosure is proposed to solve these problems and aims to reduce interference signals from vehicle-to-vehicle radar signals by using an FMCW radar that can detect the distance and speed of an object by radiating frequency-modulated radar signals, thereby alleviating factors that degrade vehicle performance, thereby preventing malfunctions and non-operations caused by generating erroneous targets during critical moments of executing vehicle control, such as braking and steering, and thus providing normal operation.

[0007] According to a first aspect of the present disclosure, a radar signal processing system is provided for obtaining a Doppler frequency from a sampled digital input signal radiated by a frequency modulated continuous wave (FMCW) radar. The system comprises: a transmitting module that repeatedly transmits a radar signal having a unique frequency variation and a pulse repetition interval; a changing module that changes the frequency variation or the pulse repetition interval of the radar signal transmitted by the transmitting module; an extraction module that extracts an interference signal from the changed radar signal when interference occurs between the radar signal having the changed frequency variation or the changed pulse repetition interval and another radar signal; and an adjustment module that adjusts the radar signal to reduce the extracted interference signal. The changing module can continuously change the frequency variation or the pulse repetition interval, and when the changing module changes the radar signal, the extraction module can extract the interference signal.

[0008] The extraction module calculates a cumulative histogram of the sampled digital input signals and extracts the interference signal from the calculated cumulative histogram. The cumulative histogram of the sampled digital input signals can be calculated by taking the absolute values ​​of the sampled digital input signals, accumulating the absolute values, and generating and accumulating a profile of all digital input signals by comparing the accumulated squared values ​​with a reference value. The extraction module can select a threshold from the calculated cumulative histogram and extract the interference signal for signals exceeding the selected threshold. The extraction module can select the threshold by calculating a value corresponding to a specific ratio from the cumulative histogram of the sampled digital input signals in the form of a power series.

[0009] The adjustment module may replace the extracted interference signal with 0 to adjust the radar signal to reduce the interference signal.

[0010] According to another aspect of the present disclosure, a radar signal processing method is provided for obtaining a Doppler frequency from a sampled digital input signal radiated by a frequency modulated continuous wave (FMCW) radar. The method includes: repeatedly transmitting, by a transmitting module, a radar signal having a unique frequency variation and pulse repetition interval; varying, by a varying module, the frequency variation or the pulse repetition interval of the radar signal transmitted by the transmitting module; extracting, by an extracting module, an interfering signal when interference occurs between the radar signal having the varied frequency variation or the varied pulse repetition interval and another radar signal; and adjusting, by an adjusting module, the radar signal to reduce the extracted interfering signal.

[0011] Changing the frequency variation or the pulse repetition interval of the radar signal by the changing module may include continuously changing the frequency variation or the pulse repetition interval, and extracting the interference signal by the extracting module when the changing module changes the radar signal.

[0012] When interference occurs between the radar signal having a varying frequency or a varying pulse repetition interval and another radar signal, extracting the interference signal by the extraction module may include calculating a cumulative histogram of the sampled digital input signal and extracting the interference signal from the calculated cumulative histogram.

[0013] Calculating the cumulative histogram of the sampled digital input signals by the extraction module and extracting the interference signal from the calculated cumulative histogram may include calculating the cumulative histogram by taking absolute values ​​of the sampled digital input signals, accumulating the absolute values, and generating and accumulating a profile of all digital input signals by comparing the accumulated squared values ​​with a reference value. Calculating the cumulative histogram of the sampled digital input signals by the extraction module and extracting the interference signal from the calculated cumulative histogram may include selecting a threshold in the calculated cumulative histogram and extracting the interference signal for signals exceeding the selected threshold.

[0014] Selecting the threshold in the calculated cumulative histogram by the extraction module and extracting the interference signal for the signal exceeding the selected threshold may include selecting the threshold by calculating a value corresponding to a specific ratio from the cumulative histogram of the sampled digital input signal in the form of a power series.

[0015] Adjusting the radar signal by the adjustment module to reduce the extracted interference signal may include adjusting the radar signal by replacing the extracted interference signal with 0 to reduce the interference signal.

[0016] According to the radar signal processing system and method disclosed herein, by using an FMCW radar capable of detecting the distance and speed of an object by radiating frequency-modulated radar signals, interference signals from vehicle-to-vehicle radar signals can be reduced to alleviate factors that degrade vehicle performance, thereby preventing malfunctions and non-operations caused by generating erroneous targets during critical moments of executing vehicle control, such as braking and steering, thereby providing normal operation.

[0017] Furthermore, the effects obtained by the present disclosure are not limited to the above-described effects, and other effects not described above will become apparent to those of ordinary skill in the art from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A radar signal processing system according to an embodiment of the present disclosure is shown;

[0019] Figure 2 is a graph showing interference when the frequencies of two radar signals vary differently and when the frequencies of the radar signals vary identically;

[0020] Figure 3is a graph showing the interference corresponding to the pulse repetition interval when the frequencies of two radar signals change at the same rate;

[0021] Figure 4 A flow chart illustrating the present disclosure of adjusting a radar signal in a sampled digital input signal to reduce an interference signal extracted from a cumulative histogram; and

[0022] Figure 5 Graph showing target loss disappearance due to failures and non-operations caused by generating erroneous targets. DETAILED DESCRIPTION

[0023] For the embodiments of the present disclosure disclosed in this specification or application, the specific structural or functional descriptions are only for the purpose of illustrating the embodiments of the present disclosure. The embodiments of the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments described in this specification or application. The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0024] Figure 1 A radar signal processing system according to an embodiment of the present disclosure is shown. Figure 2 FIG. 4 is a graph showing interference when the frequency variations of two radar signals are different and when the frequency variations of the radar signals are the same. Figure 3 FIG. 4 is a graph showing interference corresponding to the pulse repetition interval when the frequencies of two radar signals change at the same rate. Figure 4 The flowchart of the present disclosure is to adjust the radar signal in the sampled digital input signal to reduce the interference signal extracted from the cumulative histogram. Figure 5 Graph showing target loss disappearance due to failures and non-operation caused by generating erroneous targets.

[0025] Figure 1 FIG. 4 shows a radar signal processing system according to an embodiment of the present disclosure. Figure 1 A radar signal processing system for obtaining Doppler frequency from a sampled digital input signal of frequency modulated continuous wave (FMCW) radar radiation may include a processor and an associated non-volatile memory storing software instructions. When the processor executes the memory, it provides the function of a transmission module to repeatedly transmit a radar signal with a unique frequency variation and pulse repetition interval; provides the function of a variation module to change the frequency variation or pulse repetition interval of the radar signal transmitted by the transmission module; provides the function of an extraction module to extract an interference signal from the varied radar signal when interference occurs between the radar signal with the varied frequency variation or the varied pulse repetition interval and another radar signal; provides the function of an adjustment module to adjust the radar signal to reduce the extracted interference signal. The processor may take the form of one or more processors and an associated memory storing program instructions.

[0026] The present disclosure reduces interference signals from vehicle-to-vehicle radar signals by using an FMCW radar capable of detecting the distance and speed of an object by radiating frequency-modulated radar signals, thereby alleviating factors that degrade vehicle performance. This prevents malfunctions and non-operational errors caused by generating erroneous targets during critical moments of vehicle control, such as braking and steering, thereby ensuring normal operation. To this end, when a radar signal with a varying frequency or varying pulse repetition interval interferes with another radar signal, the interference signal can be extracted from the varying radar signal, and the radar signal can be adjusted to reduce the extracted interference signal.

[0027] Radar signal processing systems typically use FMCW radars, which can detect the distance and velocity of objects by radiating frequency-modulated radar signals. FMCW radars can determine the distance and velocity of an object by performing a first fast Fourier transform (FFT) on a sampled digital input signal from an analog-to-digital converter (ADC). Conventional FMCW radar signal processing equipment can determine the velocity of an object by performing a second FFT on the results of the first FFT stored for each pulse period of the radar signal to derive the Doppler frequency. When radar signal processing systems use FMCW radars to detect other vehicles and objects, mutual interference can occur, leading to false detections of missing targets or false targets. FMCW radars installed in conventional vehicles to detect other vehicles and objects are sensors that radiate electromagnetic waves and identify objects using the characteristics of received electromagnetic wave signals. However, due to interference from other radar signals, the original target signal is distorted, leading to performance degradation. Therefore, it is necessary to prevent false detections of missing targets or false targets.

[0028] Therefore, the present disclosure alleviates performance degradation factors by reducing interference signals of vehicle-to-vehicle radar signals, thereby preventing failures and non-operations caused by generating erroneous targets during critical moments of executing vehicle control, such as braking and steering, thereby ensuring normal operation.

[0029] More specifically, the transmitting module can repeatedly transmit a radar signal having a unique frequency variation and pulse repetition interval. The transmitting module can radiate radar signals from FMCW radars in vehicles, wherein the radar signal repeatedly transmits a chirp to each FMCW radar between vehicles, and a group of repeatedly transmitted chirps is defined as a frame. The radar signals have unique values ​​with different frequency variations and different pulse repetition intervals, and the type of mutual interference between radars can be classified based on the frequency variation and pulse repetition interval of the radiated radar signals.

[0030] The variation module alters the frequency variation or pulse repetition interval of the radar signal transmitted from the transmitting module. Even if each radar signal has unique values ​​for frequency variation and pulse repetition interval, if interference occurs between radar signals with the same frequency variation and pulse repetition interval between vehicles, the radar blind spot phenomenon manifests as complete interference, rendering the target completely undetectable. Therefore, the radar blind spot phenomenon, where the target is completely undetectable, only manifests as complete interference when the variation module alters the frequency variation or pulse repetition interval of the radar signal transmitted from the transmitting module. When the frequency variation or pulse repetition interval varies, transient malfunctions and non-operation may occur, rather than complete interference. In the case of transient interference, a signal larger than the normal signal enters the time domain. This can increase overall noise when performing first-order and second-order fast Fourier transforms, degrading the FMCW radar's detection performance or even rendering it undetectable. When a radar signal with a varying frequency or pulse repetition interval interferes with another radar signal, the extraction module extracts the interfering signal from the varying radar signal. In the present disclosure, the frequency variation or pulse repetition interval of a radar signal can be changed. When corresponding transient interference occurs, a cumulative histogram of the sampled digital input signal can be calculated, and the interference signal can be extracted from the calculated cumulative histogram. The extraction module can select a threshold from the calculated cumulative histogram, define signals exceeding the selected threshold as interference signals, and extract the interference signal. The variation module and the extraction module can be located in substantially the same location and can change the frequency variation or pulse repetition interval of the radar signal transmitted from the transmission module, or extract the interference signal from the changed radar signal. The adjustment module can adjust the radar signal to reduce the extracted interference signal. The radar signal can be adjusted to reduce the interference signal by replacing the interference signal with zero. This can be achieved by forming an internal algorithm in the FMCW radar to replace the data input signal corresponding to the interference signal with zero.

[0031] Figure 2 FIG. 4 is a graph showing interference when the frequency variations of two radar signals are different and when the frequency variations of the radar signals are the same. Figure 3 Graph showing interference corresponding to pulse repetition interval when the frequencies of two radar signals change the same. The variation module may continuously change the frequency change or the pulse repetition interval, and the extraction module may extract the interference signal when the variation module changes the radar signal.

[0032] Reference Figure 2 For radar signals with the same pulse repetition interval but different frequency changes, interference may occur between radar signals immediately, increasing the overall noise. Moreover, for radar signals with the same pulse repetition interval but different frequency changes, the radar blind spot phenomenon is a complete interference that makes it impossible to detect the target at all. Figure 3 ,like Figure 3As shown in the figure on the right, for radar signals with the same frequency variation but different pulse repetition intervals, transient interference only occurs in certain linear frequency modulations, but as Figure 3 As shown in the left figure, for radar signals with identical frequency variations and pulse repetition intervals, the radar blind zone phenomenon is characterized by complete interference that prevents the detection of targets. Therefore, to prevent complete interference, which can prevent radar signals with unique frequency variations and pulse repetition intervals from being detected, the variation module continuously and randomly changes the frequency variation or pulse repetition interval. This allows the extraction module to extract the interference signal from the radar signal modified by the variation module.

[0033] The extraction module can calculate a cumulative histogram of the sampled digital input signal and extract the interference signal from the calculated cumulative histogram.

[0034] The histogram divides the range of measurement values ​​into several sections, and the cumulative histogram accumulates all obtained measurement values ​​into specific sections and divides the range of measurement values ​​into several sections. The extraction module can calculate the cumulative histogram for the sampled digital input signal, and extract the interference signal from the calculated cumulative histogram by first selecting a threshold value described later and treating the signal exceeding the threshold value as the interference signal.

[0035] The cumulative histogram may be calculated by taking the absolute values ​​of the sampled digital input signals, accumulating the absolute values, and then generating and accumulating a profile for all digital input signals by comparing the accumulated squared values ​​to a reference value.

[0036] A cumulative histogram can be extracted from the sampled digital input signal and calculated by taking the absolute value of the sampled digital input signal and then calculating the number of hits between the boundary values. The total number of boundary values ​​is 64 and has 16 powers in the range of 0-2, so the histogram can be calculated by calculating the number of hits between the boundary values ​​of the sampled digital input signal. The cumulative histogram can be calculated by comparing the accumulated squared value with a reference value and generating and accumulating a profile of all digital input signals. The extraction module can select a threshold value described later using the cumulative histogram to extract the interference signal.

[0037] Figure 4 The flowchart of the present disclosure is to adjust the radar signal in the sampled digital input signal to reduce the interference signal extracted from the cumulative histogram.

[0038] Reference Figure 4 ,The extraction module can select a threshold from the calculated cumulative ,histogram and extract the interference signal for the signal exceeding the ,selected threshold.

[0039] The threshold is selected to prevent the sampled digital input signal from diverging or converging to zero (0), and the threshold can be selected empirically through multiple test data. The extraction module can select the threshold based on the specific proportion of the cumulative histogram that the frequency variation and pulse repetition interval will affect the calculation, Figure 4 As can be seen, after multiple data tests, the threshold was selected based on the 60% value of the cumulative histogram. A specific ratio can be selected based on the ratio at which instantaneous interference has little impact. Related art determines the velocity between a target and a radar by deriving the Doppler frequency based on a first-order fast Fourier transform and a second-order fast Fourier transform (rather than selecting a threshold from a cumulative histogram). However, the present disclosure selects a threshold for the sampled digital input signal after extracting the cumulative histogram from the sampled digital input signal.

[0040] The extraction module may select the threshold value by calculating a value corresponding to a specific ratio from a cumulative histogram of the sampled digital input signal in a power series form.

[0041] The power series can be a series expressed as ∑a(x-a) or a constant series. The extraction module can define the ratio at which the instantaneous interference has a smaller effect as a specific ratio to select the threshold value. For the power series, a random coefficient can be added to the exponential series, one of which can be different from the x value and the convergence or divergence state can also be different. Therefore, the cumulative histogram can be calculated by obtaining and accumulating the absolute value of the sampled digital input signal, and then generating and accumulating the profile of all digital input signals by comparing the accumulated square value with the reference value, so that the threshold value can be selected by the power series of values ​​corresponding to the specific rate in the cumulative histogram, and the sampled digital input signal is calculated from the cumulative histogram.

[0042] Figure 5 Graph showing target loss disappearance due to failures and non-operation caused by generating erroneous targets.

[0043] The adjustment module adjusts the radar signal by replacing the extracted interference signal with 0 to reduce the interference signal.

[0044] Radar signals exceeding the threshold are determined to be interference signals, so that the adjustment module can replace the sampled digital input signal corresponding to the interference signal with 0. Although instantaneous interference occurs in the radar signal as the variation module changes the frequency variation or pulse repetition interval, the interference disappears when the adjustment module replaces the sampled digital input signal corresponding to the interference signal with 0. Figure 5 , the X-axis represents time, the Y-axis represents detection distance, and the point where X is 0 represents the time point of initial target recognition. The distance detected at this time is the initial recognition distance. Figure 5 The figure above shows the interference when the FMCW radar normally detects the distance and speed of an object, where discontinuous points indicate non-detection or false detection. Figure 5 As shown in the figure below, the variation module can change the frequency variation or pulse repetition interval, and the adjustment module replaces the extracted interference signal with 0 to adjust the interference signal of the radar signal to reduce the interference signal, thereby alleviating the factors that degrade performance and preventing failures and non-operations caused by generating erroneous targets at critical moments such as executing vehicle control (such as braking and steering), thereby enabling normal operation.

[0045] A radar signal processing method for obtaining a Doppler frequency from a sampled digital input signal radiated by a frequency modulated continuous wave (FMCW) radar may include repeatedly transmitting a radar signal having a unique frequency variation and pulse repetition interval via a transmitting module; varying the frequency variation or pulse repetition interval of the radar signal transmitted by the transmitting module via a varying module; extracting the interference signal via an extracting module when interference occurs between the radar signal having the varied frequency variation or the varied pulse repetition interval and another radar signal; and adjusting the radar signal via an adjusting module to reduce the extracted interference signal.

[0046] Furthermore, changing the frequency variation or the pulse repetition interval of the radar signal by the variation module includes continuously changing the frequency variation or the pulse repetition interval, and extracting the interference signal by the extraction module when the variation module changes the radar signal.

[0047] When interference occurs between the radar signal having a varying frequency variation or a varying pulse repetition interval and another radar signal, extracting the interference signal by the extraction module may include calculating a cumulative histogram of the sampled digital input signal and extracting the interference signal from the calculated cumulative histogram.

[0048] Calculating the cumulative histogram of the sampled digital input signals by the extraction module and extracting the interference signal from the calculated cumulative histogram may include calculating the cumulative histogram by taking absolute values ​​of the sampled digital input signals, accumulating the absolute values, and generating and accumulating a profile of all digital input signals by comparing the accumulated squared values ​​with a reference value.

[0049] Calculating a cumulative histogram of the sampled digital input signal by the extraction module and extracting the interference signal from the calculated cumulative histogram may include selecting a threshold value in the calculated cumulative histogram and extracting the interference signal for signals exceeding the selected threshold value. Selecting a threshold value in the calculated cumulative histogram by the extraction module and extracting the interference signal for signals exceeding the selected threshold value may include selecting the threshold value by calculating a value corresponding to a specific ratio from the calculated cumulative histogram of the sampled digital input signal in the form of a power series.

[0050] Adjusting the radar signal to reduce the extracted interference signal by the adjustment module may include adjusting the radar signal to reduce the interference signal by replacing the extracted interference signal with zero.

[0051] As above, while the present disclosure has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various modifications and changes can be made to the present disclosure without departing from the spirit of the disclosure as provided in the appended claims.

[0052] Description of Reference Numerals

[0053] A transmitting module B changing module

[0054] C Extraction module D Adjustment module

Claims

1. A radar signal processing system for obtaining a Doppler frequency from a sampled digital input signal of a frequency modulated continuous wave (FMCW) radar radiation, the system comprising: A transmitting module that repeatedly transmits radar signals with unique frequency variations and pulse repetition intervals; a changing module, configured to change the frequency change or the pulse repetition interval of the radar signal transmitted by the transmitting module; an extraction module, configured to extract an interference signal from the varying radar signal when interference occurs between the radar signal having a varying frequency variation or a varying pulse repetition interval and another radar signal; an adjustment module, adjusting the radar signal to reduce the extracted interference signal, The extraction module calculates a cumulative histogram of the sampled digital input signal and extracts the interference signal from the calculated cumulative histogram. wherein the cumulative histogram is calculated by taking the absolute values ​​of the sampled digital input signals, accumulating the absolute values, and generating and accumulating a profile of all digital input signals by comparing the accumulated squared values ​​with a reference value, wherein the extraction module selects a threshold in the calculated cumulative histogram and extracts the interference signal for signals exceeding the selected threshold, The extraction module selects the threshold by calculating a value corresponding to a specific ratio from a cumulative histogram of the sampled digital input signal in a power series form.

2. The system according to claim 1, wherein: The changing module continuously changes the frequency change or the pulse repetition interval. When the changing module changes the radar signal, the extracting module extracts the interference signal.

3. The system according to claim 1, wherein: The adjustment module adjusts the radar signal by replacing the extracted interference signal with 0 to reduce the interference signal.

4. A radar signal processing method for obtaining a Doppler frequency from a sampled digital input signal emitted by a frequency modulated continuous wave (FMCW) radar, the method comprising: Repeatedly transmitting a radar signal having a unique frequency variation and pulse repetition interval through a transmitting module; Changing the frequency change or the pulse repetition interval of the radar signal transmitted by the transmitting module by a changing module; When interference occurs between the radar signal having a varying frequency or a varying pulse repetition interval and another radar signal, extracting the interference signal by an extraction module; adjusting the radar signal by an adjustment module to reduce the extracted interference signal, Wherein, when interference occurs between the radar signal having a varying frequency or a varying pulse repetition interval and another radar signal, extracting the interference signal by the extraction module includes calculating a cumulative histogram of the sampled digital input signal and extracting the interference signal from the calculated cumulative histogram, Wherein, calculating the cumulative histogram of the sampled digital input signal by the extraction module and extracting the interference signal from the calculated cumulative histogram includes calculating the cumulative histogram by taking the absolute value of the sampled digital input signal, accumulating the absolute value, and generating and accumulating the profile of all digital input signals by comparing the accumulated square value with a reference value, wherein calculating the cumulative histogram of the sampled digital input signal by the extraction module and extracting the interference signal from the calculated cumulative histogram includes selecting a threshold in the calculated cumulative histogram and extracting the interference signal for signals exceeding the selected threshold, Wherein, selecting the threshold in the calculated cumulative histogram by the extraction module and extracting the interference signal for the signal exceeding the selected threshold includes selecting the threshold by calculating a value corresponding to a specific ratio from the cumulative histogram of the sampled digital input signal in the form of a power series.

5. The method according to claim 4, wherein: Changing the frequency variation or the pulse repetition interval of the radar signal by the changing module includes continuously changing the frequency variation or the pulse repetition interval, and extracting the interference signal by the extracting module when the changing module changes the radar signal.

6. The method according to claim 4, wherein: Adjusting the radar signal by the adjustment module to reduce the extracted interference signal includes adjusting the radar signal by replacing the extracted interference signal with 0 to reduce the interference signal.

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