JP2014153182A - Radar device and target detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a target detection only by any of an up-chirp and a down-chirp of an FMCW (a frequency modulated continuous wave) radar device.SOLUTION: A radar device includes: a transmission section 1 that transmits an FMCW signal; a signal processor 2 that generates a beat signal from a reception signal and a transmission signal, and specifies a beat frequency from the beat signal; a beat frequency tracking section 3 that performs a tracking process of the beat frequency; the same target determination section 4 that determines whether or not a target is the same target, using a distance approximate value and a velocity approximate value obtained fo each chirp; a target information computation section 5 that computes a distance and velocity of a target pair undergoing an association as the same target; and a target output determination section 7 for an up-chirp and a target determination section 8 for a down-chirp that, when a target not deemed to be the same target is present outside an area where the target is simultaneously detected by the up-chirp and the down-chirp, using the distance approximate value of the target and the velocity approximate value thereof, directly outputs a distance of the target and a velocity thereof.

Description

  The present invention relates to a radar apparatus and a target detection method that are used for preventing collision of a moving object, traveling at a constant distance, and the like, and detecting a relative speed and distance from a target existing outside the moving object by transmitting and receiving radar waves. is there. For example, the present invention relates to an FMCW (Frequency Modulated Continuous Wave) radar apparatus.

  In the conventional FMCW radar apparatus, the target distance and speed can be detected by associating beat frequencies during up-chirping and down-chirping.

  However, in an environment with multiple targets, that is, an environment with multiple beat frequencies, it is necessary to determine which beat frequency during up-chirp corresponds to the beat frequency during down-chirp, which is extremely difficult to determine. It is.

As this countermeasure, there are those described in the following documents.
In Patent Document 1, a current target distance and speed are predicted based on a target distance and speed detected in the past, and an up-chirp beat frequency and a down-chirp beat frequency are calculated based on the predicted values. A detected pair having a frequency close to these predicted beat frequency pairs is set as a true pair.

  Patent Document 2 converts a predicted tracking value into a predicted beat frequency after target tracking, associates the predicted beat frequency with the input beat frequency, and updates the tracking estimated value.

  However, in these methods, if the target detected in the past or the target to be tracked is an erroneous target, the erroneous target will continue to remain, and there remains a problem in target detection.

  On the other hand, in Patent Document 3, the beat frequency obtained for each up-chirp and down-chirp is directly tracked, and the target distance and speed are calculated using the time-series data of the beat frequency correlated in the time direction.

  However, with this method, target pairing is performed using the target distance and speed calculated for each of the up-chirp and down-chirp, and only the target for which the pair is established is output. There was a problem that the target detected by only one of the chirps was not detected. In this regard, the conventional method of detecting the target distance and speed by associating beat frequencies at the time of up-chirp and down-chirp has the same problem.

Japanese Patent Laid-Open No. 11-271429 Japanese Patent No. 4186744 JP 2010-019824 A

  There is a high possibility that the beat frequency is not accurately associated when there is a beat frequency due to a multi-target environment or an unnecessary signal component other than the target. Also, by tracking the beat frequency in the time direction and calculating the distance and speed for each chirp, when pairing at the distance and speed, a pair is established for the target detected by only one of the chirps. There was a problem that the target was not detected.

  An object of the present invention is to detect a target even in an area where an up-chirp detection area and a down-chirp detection area do not overlap.

The radar apparatus according to the present invention transmits a frequency-modulated continuous wave to a target as a transmission signal, receives a reflected signal from the target, obtains a frequency difference between the transmitted signal and the reflected signal as a beat frequency, and from the beat frequency to the target In a radar device that calculates the distance and target speed,
A signal processor for obtaining and outputting the beat frequency of the beat signal at the time of up-chirping when the frequency of the transmission signal is increased and for obtaining the beat frequency of the beat signal at the time of down-chirping at which the frequency of the transmission signal is lowered When,
An up-chirp tracking filter for inputting an up-chirp beat frequency output from the signal processor and calculating a target distance approximate value and a target speed approximate value based on a plurality of up-chirp beat frequencies. ,
A down-chirp tracking filter for inputting a beat frequency at the time of down-chirp output from the signal processor, and calculating an approximate distance to the target and an approximate speed of the target based on a plurality of beat frequencies at the time of down-chirp ,
The detection range of the distance to the target obtained by the beat frequency during up-chirp and the detection range of the target speed are stored in the storage device as an up-chirp detection area, and the distance to the target obtained by the beat frequency during down-chirp is detected. A detection area map for storing the range and the detection range of the target speed in the storage device as a down chirp detection area;
The up-chirp detection area and down-chirp detection stored in the detection area map by inputting the approximate distance value and approximate speed value obtained by at least one of the up-chirp tracking filter and the down-chirp tracking filter From the distance approximate value and the relative speed approximate value in the area that does not overlap with the area, the distance approximate value and the relative speed approximate value to be output as the distance to the target and the target speed are determined, and the determined distance approximate value and A chirp target output determining unit that outputs the approximate relative speed value as the distance to the target and the target speed is provided.

  According to the present invention, even when the target distance / speed is in an area where the up-chirp detection area and the down-chirp detection area do not overlap, the target distance / speed can be determined and the target can be detected and the target can be tracked.

The figure which shows the principle of operation of FMCW radar. The figure which shows the example of a transmission pattern. The figure which shows a beat frequency pair. The figure which shows beat frequency time series data. The figure which shows the detection area | region of a radar apparatus. 1 is a configuration diagram of a radar apparatus 100 according to a first embodiment. FIG. 3 is a configuration diagram of an up-chirp tracking filter 31 according to the first embodiment. FIG. 3 is a diagram illustrating a detection area and an estimation error range according to the first embodiment. FIG. 3 is a configuration diagram of a radar apparatus 100 according to a second embodiment. FIG. 4 is a configuration diagram of a radar apparatus 100 according to a third embodiment.

  Embodiments of the present invention will be described below.

Embodiment 1 FIG.
In an FMCW (Frequency Modulated Continuous Wave) radar apparatus, a transmission signal that is frequency-modulated by a triangular wave-like modulation signal and repeatedly increases and decreases with a constant period as shown in FIG. 1 is transmitted as a radar wave. The radar signal reflected by the target is received, and the received signal is mixed with the transmission signal to generate a beat signal. The frequency of the beat signal (beat frequency) is specified for each sweep interval (scan interval) at the time of up chirp when the frequency of the transmission signal increases and at the time of down chirp at which the frequency decreases, and at the time of this specified up chirp Based on the beat frequency f ^u and the beat frequency f ^d at the time of down-chirping, the distance R between the radar apparatus and the target is obtained using the equations (101), (102), or (103), (104), A relative velocity V between the radar apparatus and the target is calculated. V may be referred to as a distance change rate. Hereinafter, V is referred to as a relative speed or simply a speed.

Here, B is the frequency displacement width of the transmission signal, f ₀ is the center frequency of the transmission signal, T is the time required for modulation in one cycle, and C is the speed of light. Also, assuming that the modulation time T is short, the target distance R and velocity V do not change between up-chirp and down-chirp.

  Thus, in the FMCW radar apparatus, the target distance and speed can be detected by associating beat frequencies at the time of up-chirp and at the time of down-chirp.

  However, even if the beat frequencies obtained by up-chirp and down-chirp are the same target beat frequency, an offset occurs. In particular, in an environment with multiple targets, that is, an environment with multiple beat frequencies, it is necessary to determine which beat frequency during up-chirp corresponds to the beat frequency during down-chirp, which is extremely difficult to determine. It is.

These problems will be described with reference to FIGS.
For example, it is assumed that a target is detected for each up-chirp and down-chirp as shown in FIG. 3 using a transmission pattern that repeats up-chirp and down-chirp for each scan as shown in FIG.

  The square mark in FIG. 3 is the target 1, the circle mark is the target 2, the cross mark is an unnecessary signal, and the target 2 is not detected in the down chirp. In the up chirp and the down chirp, an offset due to the target speed occurs, so that a plurality of combinations occur. Therefore, an unnecessary target may be generated, and there is a target that cannot be detected, such as target 2.

<<< Overview of Radar Device of Embodiment 1 >>>
As shown in FIG. 4, the radar apparatus according to the first embodiment directly tracks the beat frequency obtained for each up-chirp and down-chirp, and uses the time-series data of the beat frequency correlated in the time direction to Calculate distance and speed. In this method, target pairing is performed using the target distance and speed calculated for each of up-chirp and down-chirp, and the target in which the pair is established is output.

  For example, as shown in FIG. 5, the target distance / velocity range that can be detected only by up-chirp is a parallelogram region (hereinafter referred to as up-chirp detection region) that rises to the left, surrounded by a dotted line, and the target distance that can be detected only by down-chirp. The speed range is a parallelogram region (hereinafter referred to as a down chirp detection region) that rises to the right, surrounded by a broken line. However, the relative speed is within a required detection speed range, that is, a predetermined detection speed range.

  Therefore, for the target in the hexagonal region (hereinafter referred to as the pair generation possible region) where the up-chirp detection region and the down-chirp detection region overlap, a pair of beat frequencies obtained by up-chirp and down-chirp is established. Distance and speed can be detected.

  In the area where the up-chirp detection area and the down-chirp detection area do not overlap, the beat frequency pair obtained by up-chirp and down-chirp is not established, and the target distance / speed may not be detected. As described below, the radar apparatus according to the first embodiment makes it possible to detect the target distance and speed even in an area where the up-chirp detection area and the down-chirp detection area do not overlap.

<<< Configuration of Radar Device 100 >>>
FIG. 6 is a configuration diagram illustrating the radar apparatus 100 according to the first embodiment.
The radar apparatus 100 transmits a frequency-modulated continuous wave to a target as a transmission signal, receives a reflection signal from the target, obtains a frequency difference between the transmission signal and the reflection signal as a beat frequency, and calculates a distance from the beat frequency to the target. And the target speed.

  As shown in FIG. 6, the radar apparatus 100 according to the present embodiment includes a transmission unit 1, a signal processor 2, a beat frequency tracking unit 3, an identical target determination unit 4, a target information calculation unit 5, a detection area map 6, and an up A chirp target output determination unit 7 and a down chirp target output determination unit 8 are provided. The chirp target output determination unit 9 includes an up chirp target output determination unit 7 and a down chirp target output determination unit 8.

The transmitter 1 generates, as a transmission signal, a frequency-modulated continuous wave as shown in FIG. 1 by the transmitter 11 and transmits it to the target via the transmission antenna 15.
The signal processor 2 generates a beat signal from the received signal and the transmitted signal, and specifies the beat frequency from the beat signal.

  The signal processor 2 receives the reflected signal from the target via the receiving antenna 25 by the receiver 21. The analog / digital converter 22 (A / D converter 22) performs analog / digital conversion on the received signal.

Beat frequency peak detector 23, together with the frequency obtains and outputs a beat frequency f ^u of the beat signal during the up-chirp to increase the transmission signal, the beat frequency f of the beat signal during down-chirp the frequency of the transmission signal is lowered ^d is obtained and output.
The beat frequency tracking unit 3 performs beat frequency tracking processing. The beat frequency tracking unit 3 includes an up-chirp tracking filter 31 and a down-chirp tracking filter 32.

  The beat frequency tracking unit 3 directly tracks the beat frequency obtained for each up-chirp and down-chirp as shown in FIG. 4, and uses the time-series data of the beat frequency correlated with the scan interval in the time direction, And an approximate distance between the target and the target and a relative relative speed between the radar device and the target are calculated. Hereinafter, the relative speed approximate value is also simply referred to as the speed approximate value.

Up-chirp for tracking filter 31, the beat frequency f ^u at up chirp beat frequency peak detector 23 of the signal processor 2 outputs a plurality of inputs, based on the beat frequency at the time of a plurality of up-chirp, to the target An approximate distance value and an approximate target speed value are obtained.

The down-chirp tracking filter 32 inputs a plurality of down-chirp beat frequencies f ^d output from the beat frequency peak detection unit 23 of the signal processor 2, and based on a plurality of down-chirp beat frequencies, An approximate distance value and an approximate target speed value are obtained.

  As shown in FIG. 5, the detection area map 6 stores the distance detection range to the target obtained by the beat frequency at the time of up-chirping and the target speed detection range as an up-chirp detection area in the storage device and The detection range of the distance to the target obtained by the beat frequency at the time of chirp and the detection range of the target speed are stored in the storage device as a down chirp detection area.

  In FIG. 5, the pair generation possible region (the region where the up-chirp detection region and the down-chirp detection region overlap) is the target that can be determined by the beat frequency at the time of up-chirp and the target that can be determined by the beat frequency at the time of down-chirp. Is an area where there is a possibility of pairing. Conversely, the area where the up-chirp detection area and the down-chirp detection area do not overlap is the area where the target that can be obtained with the beat frequency during up-chirp and the target that can be obtained with the beat frequency during down-chirp do not pair It is.

The same target determination unit 4 inputs the distance approximate value to the target m (m = 1, 2,..., M) obtained by the up-chirp tracking filter 31 and the target speed approximate value.
The same target determination unit 4 inputs the distance approximate value to the target n (n = 1, 2,..., N) obtained by the down-chirp tracking filter 32 and the target speed approximate value.
The same target determination unit 4 determines the distance to the target in the area where the up-chirp detection area and the down-chirp detection area stored in the detection area map 6 of the approximate distance value to the target and the approximate speed value of the target are overlapped. The target m (m = 1, 2,..., M) obtained by the up-chirp tracking filter 31 and the down-chirp tracking filter 32 obtained from the approximate value and the target speed approximate value, and the target n (n = 1, 2,..., N) are determined to be the same target.

The criteria for the same target determination in the same target determination unit 4 are the distance approximate value R ^u (m) and the speed approximate value R ^{· u} (m) (R ^· : R dot of time m obtained by up-chirp means time differentiation. If the difference between the approximate distance R ^d (n) and the approximate speed R ^{· d} (n) of the target n obtained by down chirp is within a certain range, the target m and the target n are determined to be the same target. (Perform detection target pairing).

  Further, the same target determination unit 4 stores the target distance approximate value obtained by the up-chirp tracking filter 31 and the down-chirp tracking filter 32 and the target speed approximate value stored in the detection area map 6. An approximate target distance value and an approximate target speed value in a region where the up chirp detection region and the down chirp detection region do not overlap are output to the chirp target output determination unit 9.

  The target information calculation unit 5 calculates the distance R to the target and the target speed V from the pair of the beat frequency at the time of up-chirp and the beat frequency at the time of down-chirp of the target determined as the same target by the same target determination unit 4. And output.

  The chirp target output determination unit 9 includes an up-chirp detection area stored in the detection area map 6 among the approximate distance value and approximate speed value obtained by the up-chirp tracking filter 31 and the down-chirp tracking filter 32. As the distance to the target and the target speed, the distance approximate value and the relative speed approximate value (the distance approximate value and the relative speed approximate value output by the same target determination unit 4) in the area that does not overlap with the down chirp detection area. The distance approximate value and relative speed approximate value used for output are determined, and the determined distance approximate value and relative speed approximate value are output as the distance to the target and the target speed.

  The up-chirp target output determination unit 7 is an area where the up-chirp detection area and the down-chirp detection area do not overlap, and the target distance is calculated from the approximate distance value and the approximate relative speed value in the up-chirp detection area. The distance approximate value and relative speed approximate value used for outputting as the target speed are determined, and the determined distance approximate value and relative speed approximate value are output as the distance to the target and the target speed.

  The down-chirp target output determination unit 8 is an area where the up-chirp detection area and the down-chirp detection area do not overlap, and the target distance is calculated from the approximate distance value and the relative speed approximate value in the down-chirp detection area. The distance approximate value and relative speed approximate value used for outputting as the target speed are determined, and the determined distance approximate value and relative speed approximate value are output as the distance to the target and the target speed.

  The chirp target output determination unit 9 includes the up chirp target output determination unit 7 and the down chirp target output determination unit 8, but may include either one.

  The radar apparatus 100 includes a central processing unit and other hardware that performs operations of the respective units. In addition, the storage unit stores a program executed by the central processing unit, values, times, and information obtained by each unit, and values, times, and information used by each unit in a memory. Each unit of the radar apparatus 100 can refer to, add, update, and delete values, times, and information stored in the storage unit.

  The operations described below are realized by the cooperation of hardware such as a central processing unit and memory and software such as programs and data.

<<< Target Detection Method of Radar Device 100 >>>
Next, the target detection method of the radar apparatus 100 of Embodiment 1 is demonstrated.
In FIG. 6, the transmitter 11 of the transmission unit 1 transmits a transmission signal that is frequency-modulated by a triangular wave-like modulation signal as shown in FIG. Further, the transmission signal is not limited to a frequency modulation signal, and transmission signals having a constant frequency may be mixed.

  The signal processor 2 receives the transmission signal reflected by the target via the reception antenna 25, and converts the beat signal of the intermediate frequency output from the receiver 21 into an analog / digital converter 22 (A / D converter 22). To convert to a digital signal.

The beat frequency peak detection unit 23 performs frequency analysis by FFT (Fast Fourier Transform) or the like, and beat frequency f ^u _t (i) of the beat signal in up-chirp and beat frequency f ^d _t ( j) and are extracted. Here, i or j represents the number of peaks obtained by the beat frequency peak detector 23. Further, it is assumed that the time t (t = t1, t2, t3,..., Hereinafter, beat frequency observation time) when the beat frequencies are obtained is given to the beat frequencies.

  The beat frequency obtained by the beat frequency peak detection unit 23 is output to the up-chirp tracking filter 31 or the down-chirp tracking filter 32 depending on whether the beat frequency is obtained by up-chirp or down-chirp. Is done.

<<< Tracking filter 31 for up-chirp >>>
FIG. 7 is a diagram illustrating a configuration of the up-chirp tracking filter 31.
The up-chirp tracking filter 31 inputs a beat frequency at the time of up-chirp and performs a tracking process on the beat frequency.

  In the up-chirp tracking filter 31, first, the correlation unit 311 performs the following processing.

<<< correlation unit 311 >>>
The correlation unit 311 correlates the peak frequency obtained at the scan time t1 with the peak frequency obtained at the scan time t2, and associates the peak frequencies with correlation.

  For example, FIG. 4 shows that when there are two peak frequencies obtained at the scan time t1 and two peak frequencies obtained at the scan time t2, two temporary targets (a temporary target 1 indicated by a square and a circle). As a temporary target 2) shown in FIG. 2, each peak frequency is associated with a temporary target.

In FIG. 4, the peak frequencies f ^u _t1 (1) and f ^u _t2 (1) are associated with each other, and the peak frequencies f ^u _t1 (1) and f ^u _t2 (1) are determined as the peak frequencies of the temporary target 1. The peak frequencies f ^u _t1 (2) and f ^u _t2 (2) are associated with each other, and the peak frequencies f ^u _t1 (2) and f ^u _t2 (2) are determined to be the peak frequencies of the temporary target 2 Indicates. In addition, the process which calculates the true value of a beat frequency using the estimated beat frequency of the existing temporary detection target with respect to the associated peak frequency is also performed.

<<<< Initialization Unit 312 >>>>
When the correlation unit 311 determines that there is no correlation, the initialization unit 312 sets the beat frequency that has not been correlated as the new target as the initial target smoothing value. The initial smoothing value of the temporary target set by the initializing unit 312 is assigned with the beat frequency acquisition time (hereinafter, update time).

<<< Smoothing part 313 >>>
On the other hand, when the correlation unit 311 determines that there is a correlation, the correlation unit 311 outputs the beat frequency to the smoothing unit 313, and the smoothing unit 313 updates the temporary target beat frequency smoothing value. The provisional target beat frequency smoothed value updated by the smoothing unit 313 is given a beat frequency acquisition time (hereinafter referred to as update time).

<<< Distance / Speed Converter 315 >>>
The beat frequency smoothed value updated by the smoothing unit 313 is output to the distance / speed converting unit 315, and the approximate distance value and approximate speed value are calculated. The approximate distance value is an approximate distance value from the radar apparatus 100 to the target. The approximate speed value is an approximate relative speed value between the radar apparatus 100 and the target.

<<< Processing of Up Chirp Tracking Filter 31 >>>
The processing of the up-chirp tracking filter 31 will be described with reference to FIG. The processing follows Formula (1) to Formula (26).

The state vector of the temporary target number m (m = 1, 2,..., M) used in the up-chirp tracking filter 31 is defined by equation (1), and the motion model is defined by equation (2).
In equation (1),
x is the beat frequency vector,
Superscript u is chirp up,
The subscript k is the sampling number,
M in () is the target number,
f ^u _k is the beat frequency of the up chirp,
f ^{· u} _k is the beat frequency change rate of up-chirp,
T represents transposition.
The beat frequency change rate means the amount of time change of the beat frequency, and is a relationship of speed to position.

In the formula (2), phi _k is the state transition matrix to the time t _{k + 1} from the time t _k represented by equation (3), it is assumed that the constant velocity linear motion the motion of the target.

Δt in the equation (3) is a difference time between the sweep times t (k) and t (k + 1).
In Equation (4), 0 is an average value, and Q _k is a drive noise covariance matrix. w _k is a drive noise vector at time t (k), and has an average value 0 and variance Q _k as shown in equation (4).

Furthermore, an observation matrix H is defined by equation (6), and an observation model is represented by equation (5). f ^u _k is an observed value of the beat frequency.

Here, A _k of the formula (7) is an observation error variance of the beat frequency.
In equation (7), v _k is an observation noise with an average value of 0 and an observation error variance A _k .

  In the upchirp tracking filter 31, the correlation unit 311 determines that the beat frequency has a correlation with the provisional target m when the inequality of Expression (8) is satisfied.

In Expression (8), f ^u _{k | k−1} (m) represents the predicted beat frequency of the temporary target obtained by the prediction unit 314 described later. In Expression (8), d is a determination threshold value, and S is a residual variance of the temporary target m defined by Expression (9).

In Equation (9), P ^u _{k | k−1} is a prediction error covariance matrix, and the calculation is performed by the prediction unit 314 described later. In Expression (10), f ^u _{k | k−1} is a predicted value of the beat frequency at the time t (k) of the temporary target obtained by the prediction unit 314 described later, and the beat frequency vector at the time t (k). ^Is calculated by the equation (10) from the predicted values x to ^u _{k | k−1} .

<<< Processing of Initialization Unit 312 in Case of No Correlation >>>
When there is no provisional target whose beat frequency satisfies the inequality of Expression (8), the correlation unit 311 regards that there is no correlation, and the initialization unit 312 registers the beat frequency as a new provisional target. As a registration method, a beat frequency and an observation error covariance matrix are set as a smoothing vector initial value and a smoothing error covariance matrix initial value as shown in the equations (11) and (12), and are given to the beat frequency. Set the time. Here, for example, A ₀ is set as the beat frequency observation error variance at the initial time, and ν _max is set as the maximum value of the beat frequency change rate.

The initialization unit 312 uses the form of the initial values of the beat frequency vector x ^u ₀ (m) and the smoothing error covariance matrix P ^u ₀ (m) shown in Equations (11) and (12) to generate a smooth value vector. And set the smoothing error covariance matrix. In Expression (12), P ^u ₀ (m) is an observation error variance matrix, and ν _max is a maximum value of the beat frequency change rate. The time given to the beat frequency is also set.

  Further, the initialization unit 312 sets 0 as the track quality TQ value for the new temporary target, as shown in Expression (13). Further, the total number M of temporary targets is increased by one.

<<< Processing of the smoothing unit 313 when there is a correlation >>>
When the beat frequency satisfies the inequality of equation (8), the correlation unit 311 considers that there is a correlation, and the smoothing unit 313 uses the beat frequency considered to be correlated as an observation value vector of the correlated temporary target m. Then, the state update of the temporary target m is performed by the equations (14) to (16).

In the equation (14), the beat frequency smoothed value vector x ^ ^u _{k | k} at time t (k) is used, the observed beat frequency f ^u _k , and the state vector predicted values x to ^u _{k | k−1} . To calculate.
Here, the beat frequency smoothed value vector is constructed by the beat frequency smoothed value f ^ ^u _k and the beat frequency variation rate smoothed value f ^ ^{· u} _k. The beat frequency smoothed value vector is obtained by adding a hat (^) to all terms in the equation (1). A hat (^) means a smooth value.
x ^u _k (m) = [f ^u _k f ^{· u} _k ] ^T (1)
Further, the smooth error covariance matrix P ^u _{k | k} is calculated by the equation (15). Further, the gain matrix K ^u _k is defined by Expression (16).

  Further, the smoothing unit 313 increases the track quality TQ value for the temporary target m by 1. At this time, as shown in Expression (17), when the TQ value exceeds the preset upper limit value TQmax, it is fixed at TQmax.

In Expression (16), S ^u _k (m) is a residual covariance matrix of the provisional target m. In Equation (15), I is a secondary unit matrix, P ^u _{k | k−1} (m) is the prediction error covariance matrix of the temporary target m, and P ^u _{k | k} (m) is the smoothing error of the temporary target m. A covariance matrix, K ^u _k, is a gain matrix of the temporary target m.

Also, when a correlated beat frequency is not obtained for the registered temporary target m, processing is performed as shown in equations (18) and (19) as a memory track. The beat frequency smoothing vector x ^ ^u _{k | k} at time t (k) is calculated by equation (18), and the smoothing error covariance matrix P ^u _{k | k} is calculated by equation (19). Further, the TQ value is decreased by 1 as a memory track (formula (20)). At this time, if the TQ value falls below the preset lower limit value TQmin, the TQmin is fixed.

<<< Processing of Prediction Unit 314 >>>
The prediction unit 314 calculates a difference Δt between the update time given to the smooth value and the beat frequency observation time newly supplied by the beat frequency peak detection unit 23 with respect to the smooth value obtained in this way. Then, after calculating the state transition matrix of Equation (3), the state quantity is adjusted to the beat frequency observation time according to Equations (21) and (22).

That is, the prediction unit 314 obtains the smoothing vector, smoothing error covariance matrix corresponding to the time t (k) obtained by the smoothing unit 313, or the smoothing corresponding to the time t (k) set by the initialization unit 312. Using a vector and a smooth error covariance matrix, a prediction vector x to ^u _{k + 1 | k} and a prediction error covariance matrix P ^u _{k + 1 | k} corresponding to time t (k + 1) are calculated (formulas (21) and (22)). ). The state transition matrix Φ _k used in the calculation is the difference Δt (= t (k + 1) between the time t (k + 1) and the time t (k) newly assigned to the beat frequency supplied by the beat frequency peak detection unit 23. ) -T (k)), the calculation is performed using Equation (3).

  The smooth value vector and smooth covariance matrix calculated by the prediction unit 314 are used in the correlation processing at the time t (k + 1) in the correlation unit 311 described above. The process described above is repeated for each sweep time (scan time).

<<< Distance / Speed Converter 315 >>>
The distance / velocity conversion unit 315 inputs time series data of the beat frequency at the time of up-chirp correlated with the temporary target m, and performs target detection determination on the temporary target. Further, the detected approximate distance value and approximate speed value of the target are calculated.

  For example, in the distance / speed conversion unit 315, first, the TQ value of the temporary target m (m = 1, 2,..., M) is sequentially input, and when the TQ value exceeds a predetermined TQthre (threshold). Thus, it is determined that the target is detected for the temporary target.

  A temporary target determined to be target detection is called a detection target. In the up-chirp tracking filter 31, the time-series data of correlated beat frequencies at the time of up-chirp, which is the tracking processing result corresponding to the detection target, that is, a collection of beat frequencies at different sampling times is held in the storage unit. Yes.

The target distance approximate value R ^u ₀ (m) and the speed approximate value R ^{· u} ₀ (m) at the reference sampling time t ₀ are defined, and the target distance approximate value R ^u _k (at an arbitrary sampling time t _k is defined. m), the approximate velocity value R ^{· u} _k (m) is modeled. Furthermore, to define a state transition matrix by the reference time t ₀ and the time difference between any sampling time _{t k Δ (Δ = t k} -t 0), the distance schematic at the reference time the beat frequency during the up-chirp at any time Expressed by value and approximate speed value.

The beat frequency f ^u ₀ (m) at the time of up-chirping the temporary target m at the reference sampling time t ₀ , the target distance approximate value R ^u ₀ (m), and the target speed approximate value R ^{· u} ₀ (m )), It is assumed that there is a relationship of the equation (23).

The beat frequency f ^u _k (m) at the time of up-chirping the temporary target m at an arbitrary sampling time t (k), the target distance approximate value R ^u ₀ (m), and the target speed approximate value R ^{· u} _It is assumed that there is a relationship of Expression (24) with ₀ (m).

Thus, the distance and speed conversion section 315 receives as input the beat frequency smoothed value of the up-chirp and the beat frequency variation rate smoothed value, converted to a distance approximate values R ^u and velocity approximate values R ^{· u.}
Alternatively, for example, the beat frequency is accumulated for two scans, and calculation is performed by using equations (23) and (24). Here, the beat frequency for two scans is used without using the beat frequency change rate.
Equation (23) means the beat frequency observation value f ^u ₀ (m) of the target number m at the sampling number 0.
Expression (24) means the beat frequency observation value f ^u _k (m) of the target number m at the sampling number k.
Further, the distance approximate value R ^u and the speed approximate value R ^{· u} may be calculated using the equations (25) and (26).
F ^ ^{· u} _t of formula (25) is a beat frequency rate of change smoothed value of sampling number k in the up-chirp.
Ƒ ^u _t in the equation (26) is a beat frequency smoothing value of the sampling number k in up-chirp.
Equation (25) inputs the beat frequency variation rate smoothed value f ^ ^{· u} _t, a conversion formula for converting the speed approximate values R ^·.
Expression (26) is a conversion expression for converting the beat frequency smooth value f ^ ^u _t into an approximate distance value R using the beat frequency smoothing value f ^{u u} _t as an input.
Expressions (25) and (26) are expressions in which expressions (23) and (24) are expressed by distance R ^u ₀ (m) and velocity R ^{· u} ₀ (m).
In addition, Formula (24) is made into f ^u _k using the symbol k showing a sampling number because it is a beat frequency observation value. On the other hand, since the expressions (25) and (26) are smooth values, the notation is differentiated and the symbol representing the time is set to f ^u _t using t.

Although illustrates processing of up-chirp for tracking filter 31 in the formula (1) to (26), without limitation to this process, as an input the beat frequency of the up-chirp, and the distance approximate values R ^u rate Any process that calculates the approximate value R ^{· u} may be used.

  When an angle is given to the beat frequency, the same tracking process may be performed for the angle. At that time, the basic processing follows formulas (1) to (26). However, it shows below about a different place from a formula (1)-a formula (26).

The state vector of the angle of the temporary target number m (m = 1, 2,... M) is defined by Expression (31), and the motion model is defined by Expression (32). θ ^u _k represents an angle, and θ ^{· u} _k represents an angular velocity. Further, the observation matrix is defined by Expression (33), and the observation model is represented by Expression (32).

Further, when a phase difference between receiving antennas before angle calculation is given to the beat frequency, the same tracking process may be performed for the phase difference instead of the angle. At that time, the basic processing follows formulas (1) to (26) and formulas (31) to (33). Here, the formula (41) a phase difference phi ^u _k the angle theta ^u _k as to Formula (43), may be replaced with angular theta ^· _{u k} to the phase difference change rate φ ^· _{u k.}

<<< Processing of Down Chirp Tracking Filter 32 >>>
The processing and operation of the down-chirp tracking filter 32 are the same as those of the up-chirp tracking filter 31.

  The same operation is performed by changing the superscript u of the state vector in Expressions (1) to (26), Expressions (31) to (33), and Expressions (41) to (43) to d. In the distance / velocity conversion unit of the down-chirp tracking filter 32, the subscript u of each variable is changed to d for down chirp, and the sign of the second term on the right side of the equation (26) is a positive sign ( It is necessary to use the one changed to (+), but the other procedures are the same, so a detailed description is omitted.

<<< Same Target Determination Unit 4 >>>
The same target determination unit 4 inputs the outputs of the up-chirp tracking filter 31 and the down-chirp tracking filter 32, and performs the same target determination of the detection target during up-chirp and the detection target during down-chirp.

As a criterion for the same target determination, the target m approximate distance value R ^u and the speed approximate value R ^{· u} obtained by up-chirp, the target n distance approximate value R ^d and the speed approximate value R ^{· d} obtained by down-chirp are used. If the difference is within a certain range, the same target is determined. As an example of the determination method of the same target, for example, when the equations (51) and (52) are simultaneously established or when the inequality such as the equation (53) is satisfied, the same target is determined. Here, σ _R means distance estimation accuracy, σ _{R ·} means velocity estimation accuracy, and ThR, ThV, and ThRV mean threshold values. σ _R and σ _{R ·} are obtained by replacing the prediction error covariance matrix P _{k | k−1} in Expression (9) with the smooth error covariance matrix P _{k | k} in Expression (15).

  When there are a plurality of combinations that satisfy the expressions (51) and (52) at the same time or satisfy the expression (53) in the same target determination unit 4, the evaluation values of the expressions (51), (52), and (53) Select the lowest combination and output beat frequency pairs for up and down chirps.

When an angle measurement value is given to the beat frequency, a pair that satisfies the expressions (51), (52), and (54) at the same time or satisfies the expression (55) may be output. Here, sigma _theta is angle measuring observation accuracy, Thθ, ThRVθ means threshold. When using a phase difference instead of an angle, θ in the equations (54) and (55) may be replaced with φ.

<<< Processing of Target Information Calculation Unit 5 >>>
The process of the target information calculation unit 5 will be described.
The target information calculation unit 5 calculates the distance and speed using the target pair output from the same target determination unit 4 as an input.

  The target information calculation unit 5 calculates the distance R / velocity V from the pair of up-chirp and down-chirp beat frequencies using equations (103) and (104). In addition, as other distance / speed calculation methods, the approximate distance value / velocity value in either chirp is output as the distance R / velocity V, or the approximate distance / velocity value of each chirp is weighted with the estimation error. It is also possible to use the calculation method.

The up-chirp target output determination unit 7 correlates time series data (at least two pieces of time series data) outside the pair generation possible area, calculates and outputs the target distance and speed having the correlation. Since the distance and speed cannot be calculated unless at least two pieces of time-series data are correlated, the up-chirp target output determination unit 7 calculates and outputs only the distance and speed of the correlated target.
The up-chirp target output determination unit 7 inputs the approximate distance to the target obtained by the up-chirp tracking filter 31 and the approximate target speed, and stores the up-chirp detection region stored in the detection region map 6. Among them, the approximate distance to target and the approximate target speed in the area where the up-chirp detection area and the down-chirp detection area do not overlap are output as the distance to the target and the target speed.

  The up-chirp target output determination unit 7 receives from the same target determination unit 4 an approximate distance to target target and a target speed approximate value that were not determined to be the same target by the same target determination unit 4, A target that is outside the region where the up-chirp detection region and the down-chirp detection region stored in the detection region map 6 overlap (a pair generation possible region) is determined.

  The up-chirp target output determination unit 7 determines whether or not the target is outside the pair generation possible area stored in the detection area map 6, and sets only the target outside the pair generation possible area as an output target. To do.

  That is, the up-chirp target output determination unit 7 receives only the targets that have not been paired within the process of the same target determination unit 4 from the targets output from the same target determination unit 4, and detects the detection region map 6. , Only the target whose rough distance value / speed rough value of the target is outside the pair generation possible region in FIG. 5 is output.

  Here, the up-chirp target output determination unit 7 determines only targets whose TQ value exceeds a predetermined TQthre (threshold value) from among targets whose pair is not established within the process of the same target determination unit 4. It is good as a target.

  That is, the up-chirp target output determining unit 7 calculates the correlation of beat frequencies and pays attention to an index (for example, TQ value) indicating tracking continuity obtained based on the correlation, and tracking continuity for this target. Only a target for which the index representing the value is a certain value or more may be determined.

The up-chirp target output determination unit 7 determines whether the target approximate distance value and approximate speed value are within or out of the pair-generating area, for the target existing near the boundary of the area. The determination may be made in consideration of the estimation error of the value / speed approximate value. For example, the estimated error P ^u _{RV, k} of the approximate distance value and approximate speed value of the up-chirp can be derived from the equations (25) and (26) as in the equations (61) and (62). Here, the first row and first column of P ^u _{RV, k represent} the estimated error variance of the approximate distance value, and the second row and second column represent the estimated error variance of the approximate velocity value. Further, the estimated error P ^d _{RV, k} of the approximate distance value and approximate speed value of the down chirp is expressed by equations (63) and (64).

  Therefore, the up-chirp target output determination unit 7 can generate a pair of targets when the range in which the estimation error is considered centered on the target approximate distance value and approximate speed value includes a part of the pair generation possible region. Judge as in the area and do not output directly. For example, in the situation as shown in FIG. 8, for the target i, since the range in which the estimation error is taken into account includes a part of the pair generation possible region, the target i is not output. For the target j, the target j is output because the range in which the estimation error is taken into consideration does not include the pair generation possible region.

  As described above, the up-chirp target output determination unit 7 has a possible range due to an estimation error between the approximate distance to the target and the approximate target speed with the approximate approximate distance to the target and the approximate target speed as the center. However, only a target outside the region where the up-chirp detection region and the down-chirp detection region overlap is set as the determination target.

  In addition, when it is difficult for the upchirp target output determination unit 7 to determine at a certain time alone, for example, M times in the past N samples (N ≧ M), the target can be pair generated within the region where the above condition is satisfied. May be determined.

  As described above, the up-chirp target output determination unit 7 determines only a target in which the target does not enter the region where the up-chirp detection region and the down-chirp detection region overlap more than M times in the past N times (N ≧ M). And

As a result, it is possible to reduce the possibility that the target that should exist in the pair generation possible region is erroneously output directly.
On the other hand, the up-chirp target output determination unit 7 shifts the target approximate distance value and approximate speed value outside the pair generation possible area in up-chirp for a target that has already been paired with up-chirp and down-chirp. If you do, you may output directly.
This makes it possible to improve target tracking continuity.

<<< Processing of Target Output Determination Unit 8 for Down Chirp >>>
The down-chirp target output determination unit 8 inputs the approximate distance to the target and the approximate target speed obtained by the down-chirp tracking filter 32 and stores the down-chirp detection area stored in the detection area map 6. Among these, the approximate distance to target and the approximate target speed in the area where the up-chirp detection area and the down-chirp detection area do not overlap are output as the distance to the target and the target speed.

  The down-chirp target output determination unit 8 is processed in the same procedure as the up-chirp target output determination unit 7, and thus the description thereof is omitted.

  As described above, according to the radar apparatus according to the first embodiment, the beat frequency tracking process obtained by up-chirp and the beat frequency tracking process obtained by down-chirp are individually performed in a multi-target environment, and each tracking process is performed. To calculate the approximate distance and approximate speed. If the target distance approximate value / speed approximate value is outside the pair generation possible region, the target information is directly output. Therefore, a target that can be detected only by one-side chirp, which could not be detected by the conventional pairing method between up and down chirps, can be detected by the present embodiment.

<<< Summary >>>>
As described above, the radar apparatus 100 according to the first embodiment includes the transmission unit 1 that generates a transmission signal that periodically repeats frequency increase and decrease linearly with a constant modulation width and transmits the transmission signal as a transmission signal. ing.

  The radar apparatus 100 receives the transmission signal reflected by the reflector and generates a reception signal. The radar apparatus 100 mixes the reception signal with the transmission signal to generate a beat signal, and generates a beat frequency from the beat signal. A signal processor 2 to be identified is included.

  The radar apparatus 100 includes an up-chirp tracking filter 31 and a down-chirp tracking filter 32 that perform tracking processing on frequency peaks obtained during each chirp observation and calculate a target distance and speed.

  The radar apparatus 100 includes the same target determination unit 4 that determines whether or not the targets detected for each chirp are the same target using the target distance and speed calculated for each chirp.

  The radar apparatus 100 includes a target information calculation unit 5 that calculates a distance and a speed from a pair of up-chirp and down-chirp of a target regarded as the same target.

  The radar apparatus 100 uses the distance and speed of a target that is not determined to be the same target by the same target determination unit, and determines that the target is outside the region that is simultaneously detected by up-chirp and down-chirp. A determination unit 9 is provided.

  The chirp target output determination unit 9 is characterized in that only targets whose index indicating tracking continuity is a certain value or more are determined.

  Further, when the radar device 100 determines that the target output determination unit 9 for chirp is outside the region detected by up-chirp and down-chirp using the target distance and speed, the target information is directly output. It is characterized by doing.

  Further, the radar apparatus 100 does not include any region in the chirp target output determination unit 9 in which the possible range due to the estimation error is detected at the same time by up-chirp and down-chirp, centering on the target distance and speed. In addition, the target information is directly output.

  In addition, the radar apparatus 100 uses the target output determination unit 9 for each chirp to enter the region where the target is simultaneously detected by up-chirp and down-chirp using the target distance and speed at least M times in the past N times. If not, the target information is directly output.

  In this embodiment, the approximate distance value and approximate speed value are calculated using a tracking filter that inputs the beat frequency in each chirp, and the target approximate distance value and approximate speed value are detected simultaneously by up-chirp and down-chirp. When it is outside the area, the target distance that has not been detected in the past can be detected and the target detection range can be expanded by directly outputting the approximate distance value and approximate speed value.

Embodiment 2. FIG.
In this embodiment, differences from the first embodiment will be mainly described.
FIG. 9 is a configuration diagram illustrating the radar apparatus 100 according to the second embodiment.
As shown in FIG. 9, the radar apparatus according to the present embodiment includes a transmission unit 1, a signal processor 2, a beat frequency tracking unit 3, a same target determination unit 4, a target information calculation unit 5, a detection area map 6, and an up-chirp. Target output determining unit 7 and down chirp target output determining unit 8.

Next, the operation will be described.
However, the description of the same processing as in the first embodiment is omitted.
The up-chirp target output determination unit 7 refers to the detection area map 6, and the target distance approximate value / velocity approximate value obtained as the output of the up-chirp tracking filter 31 is outside the pair generation possible area of FIG. Only output directly. Other than the above-mentioned target, it outputs to the same target determination part 4.

  Since the down chirp target output determination unit 8 performs the same procedure, the description thereof is omitted.

  As described above, in the second embodiment, each target output determination unit for chirp directly outputs a target using the target distance and speed calculated by the up-chirp tracking filter and the down-chirp tracking filter. It is determined whether or not to perform, and only a target that is not directly output is output to the same target determination unit.

  In the second embodiment, the same effect as in the first embodiment can be obtained, and at the same time, in the same target determination unit 4, it is necessary to calculate a pair of up-chirp and down-chirp for a target that is outside the pair generation possible region. Therefore, the processing load is reduced.

Embodiment 3 FIG.
In this embodiment, differences from the first embodiment will be mainly described.
FIG. 10 is a configuration diagram illustrating the radar apparatus 100 according to the third embodiment.
The same target determination unit 4 performs processing in the same procedure as in the first embodiment. However, targets that are not used for pairing are not output to the up-chirp target output determination unit 7 and the down-chirp target output determination unit 8 but are ignored.

  The up-chirp target output determination unit 7 refers to the detection region map 6 and inputs all the target distance approximate values and speed approximate values obtained as the output of the up-chirp tracking filter 31 to generate the pair shown in FIG. Directly output only targets that are out of range. The target information other than the target is ignored.

  Since the down chirp target output determination unit 8 performs the same procedure, the description thereof is omitted.

  As described above, in the third embodiment, since each chirp target output determination unit and the same target determination unit operate individually, there is a problem in each chirp target output determination unit and the same target determination unit. Are also characterized in that they do not affect each other.

  DESCRIPTION OF SYMBOLS 1 Transmission part, 2 Signal processor, 3 Beat frequency tracking part, 4 Same target determination part, 5 Target information calculation part, 6 Detection area map, 7 Up chirp target output determination part, 8 Down chirp target output determination part, 9 Target output determination unit for chirp, 11 Transmitter, 15 Transmit antenna, 21 Receiver, 22 Analog / digital converter, 23 Beat frequency peak detection unit, 25 Receive antenna, 31 Up-chirp tracking filter, 32 Down-chirp tracking Filter, 100 radar device, 311 correlation unit, 312 initialization unit, 313 smoothing unit, 314 prediction unit, 315 distance / velocity conversion unit.

Claims (8)

A frequency-modulated continuous wave is transmitted to the target as a transmission signal, a reflected signal from the target is received, a frequency difference between the transmitted signal and the reflected signal is obtained as a beat frequency, a distance from the beat frequency to the target, a target speed, In a radar device that calculates
A signal processor for obtaining and outputting the beat frequency of the beat signal at the time of up-chirping when the frequency of the transmission signal is increased and for obtaining the beat frequency of the beat signal at the time of down-chirping at which the frequency of the transmission signal is lowered When,
An up-chirp tracking filter for inputting an up-chirp beat frequency output from the signal processor and calculating a target distance approximate value and a target speed approximate value based on a plurality of up-chirp beat frequencies. ,
A down-chirp tracking filter for inputting a beat frequency at the time of down-chirp output from the signal processor, and calculating an approximate distance to the target and an approximate speed of the target based on a plurality of beat frequencies at the time of down-chirp ,
The detection range of the distance to the target obtained by the beat frequency during up-chirp and the detection range of the target speed are stored in the storage device as an up-chirp detection area, and the distance to the target obtained by the beat frequency during down-chirp is detected. A detection area map for storing the range and the detection range of the target speed in the storage device as a down chirp detection area;
The up-chirp detection area and down-chirp detection stored in the detection area map by inputting the approximate distance value and approximate speed value obtained by at least one of the up-chirp tracking filter and the down-chirp tracking filter From the distance approximate value and the relative speed approximate value in the area that does not overlap with the area, the distance approximate value and the relative speed approximate value to be output as the distance to the target and the target speed are determined, and the determined distance approximate value and A radar apparatus comprising: a chirp target output determination unit that outputs a relative speed approximate value as a distance to a target and a target speed. The target output determination unit for chirp is
The up-chirp detection area and the down-chirp detection area among the up-chirp detection areas stored in the detection area map by inputting the approximate distance to the target and the approximate speed of the target obtained by the up-chirp tracking filter A target output determination unit for up-chirp that outputs an approximate distance to a target and an approximate target speed in a region that does not overlap with each other as a target distance and a target speed;
The up-chirp detection area and the down-chirp detection area of the down-chirp detection area stored in the detection area map by inputting the approximate distance to the target and the approximate speed of the target obtained by the down-chirp tracking filter A target output determination unit for down chirp that outputs an approximate distance to a target and an approximate target speed in a region that does not overlap with each other as a distance to the target and a target speed. The radar apparatus according to 1. The radar device further includes:
The up-chirp detection area and down-chirp detection stored in the detection area map by inputting the approximate distance to the target and the approximate speed of the target obtained by the up-chirp tracking filter and the down-chirp tracking filter Whether the target obtained by the up-chirp tracking filter and the target obtained by the down-chirp tracking filter are the same target from the approximate distance to the target and the approximate velocity of the target in the overlapping area The same target determination unit for determining whether or not,
A target information calculating unit that calculates a distance to the target and a target speed by a pair of beat frequency at the time of up-chirping and beat frequency at the time of down-chirping of the target determined as the same target by the same target determining unit;
With
The chirp target output determination unit inputs an approximate distance to a target of a target that was not determined to be the same target by the same target determination unit and an approximate target speed from the same target determination unit, and the target is 3. The radar apparatus according to claim 1, wherein it is determined that the up-chirp detection area and the down-chirp detection area stored in the detection area map are outside the overlapping area.   The chirp target output determination unit determines whether the target is outside the region where the up-chirp detection region and the down-chirp detection region stored in the detection region map overlap with each other. 4. The radar apparatus according to claim 3, wherein only a target outside an area overlapping with the down chirp detection area is set as a determination target.   The chirp target output determination unit calculates a correlation between the beat frequencies, obtains an index indicating tracking continuity based on the correlation, and only targets for which the index indicating tracking continuity for the target is a certain value or more The radar apparatus according to any one of claims 1 to 4, wherein the target is an output target.   The target output determination unit for chirp detects an up-chirp detection based on an estimation error between an approximate distance to a target and an approximate target speed with an approximate distance to target and approximate target speed as a center. 6. The radar apparatus according to claim 1, wherein only a target outside a region where the region and the down chirp detection region overlap is set as an output target.   The chirp target output determination unit sets only targets for which the target does not enter M or more (N ≧ M) in the past N times in an area where the up-chirp detection area and the down-chirp detection area overlap. The radar device according to claim 1. A frequency-modulated continuous wave is transmitted to the target as a transmission signal, a reflected signal from the target is received, a frequency difference between the transmitted signal and the reflected signal is obtained as a beat frequency, a distance from the beat frequency to the target, a target speed, In a radar apparatus target detection method for
The radar device stores the distance detection range to the target obtained with the beat frequency at the time of up-chirp and the target velocity detection range in the storage device as an up-chirp detection area, and the target to be obtained with the beat frequency at the time of down-chirp. A detection area map for storing a distance detection range and a target speed detection range as a down chirp detection area in a storage device,
A signal processor obtains and outputs the beat frequency of the beat signal at the time of up-chirping when the frequency of the transmission signal increases, and obtains the beat frequency of the beat signal at the time of down-chirping when the frequency of the transmission signal decreases. Output,
The up-chirp tracking filter inputs up-chirp beat frequency output from the signal processor, and based on a plurality of up-chirp beat frequencies, calculates an approximate distance to the target and approximate target speed. Seeking
The down-chirp tracking filter inputs the beat frequency at the time of down-chirp output from the signal processor, and calculates the approximate distance to the target and the approximate speed of the target based on the beat frequencies at the time of multiple down-chirps. Seeking
The chirp target output determination unit inputs the approximate distance value and approximate speed value obtained by at least one of the up-chirp tracking filter and the down-chirp tracking filter, and is stored in the detection area map. From the approximate distance value and relative approximate speed value in the area where the up chirp detection area and the down chirp detection area do not overlap, the approximate distance value and relative approximate speed value output as the target distance and target speed are determined. And outputting the determined approximate distance value and approximate relative speed value as the distance to the target and the target speed.

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