JP3223697B2 - Radar signal processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, correction of a phase shift of a target reception signal in a radar signal processing device of a high resolution radar device.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram of a radar signal processing device of a high-resolution radar device. In the drawing, reference numeral 1 denotes a data interface unit for converting a target reception signal input from the radar device into a data format that can be processed internally. Reference numeral 2 denotes a pulse compression unit for pulse-compressing the target reception signal converted by the data interface unit 1. Reference numeral 3 denotes a distance correction unit for correcting a time-dependent distance shift of the target reception signal pulse-compressed by the pulse compression unit 2. A phase correction unit for correcting a phase shift due to time of the target reception signal corrected by the distance correction unit 3; a frequency analysis unit 5 for separating the Doppler frequency of the target reception signal corrected by the phase correction unit 4; A detector 7 converts the frequency spectrum of the target reception signal, which has been frequency-analyzed by the unit 5, into image data. Reference numeral 7 denotes an interface between the image data obtained by the detector 6 and the display. A display interface unit for adjusting display time and generating display image data, SM is a target reception signal input from the radar device, RS is a target reception signal whose distance deviation due to time has been corrected by the distance correction unit 3, and RG is a radar and target. An initial distance from the center of gravity, RD is a target reception signal whose phase shift due to time has been corrected by the phase correction unit 4, and D is display image data.

FIG. 7 is a block diagram of a conventional phase correction unit 4 in the radar signal processing apparatus of FIG.
G, RD and 4 are the same as in FIG.
A buffer circuit for storing the target reception signal RS and the initial distance RG between the radar and the target center of gravity corrected by the output time-dependent distance shift, and an initial distance RG between the radar output from the buffer circuit 8 and the target center of gravity. A frequency analysis circuit for frequency-analyzing the target reception signal in a small section in the time direction at 10 in the frequency and amplitude waveforms obtained by the frequency division analysis circuit 9 as a reference point frequency. A maximum amplitude value detection circuit to be detected, 11 is a smoothing circuit for smoothing the locus of the reference point frequency detected by the maximum amplitude value detection circuit 10 in the time direction, and 12 is a reference point frequency smoothed by the smoothing circuit 11. A phase correction amount calculating circuit for calculating a phase correction amount from a trajectory in the time direction of the phase correction amount calculating circuit; Phase correcting circuit for correcting the phase of the target received signal outputted from the circuit 8, GS is the target received signal in the initial distance RG between the radar and the target centroid.

Next, the operation will be described. The target reception signal SM input from the radar device is converted into a data format that can be processed internally by the data interface unit 1, pulse-compressed by the pulse compression unit 2, and corrected by the distance correction unit 3 for a distance shift due to time. The signal is output to the phase correction unit 4 as the target reception signal RS. Further, the distance correction unit 3 calculates an initial distance RG between the radar and the target center of gravity, and outputs the calculated initial distance RG to the phase correction unit 4. The phase correction unit 4 corrects the time-dependent phase shift of the target reception signal RS using the target reception signal RS whose distance shift due to time has been corrected and the initial distance RG between the radar and the target center of gravity, and performs frequency analysis as the target reception signal RD. Output to section 5. The target reception signal RD is converted into a frequency spectrum by being frequency-analyzed by the frequency analysis unit 5 and converted into image data by the detection unit 6, and then the display interface unit 7 adjusts the interface with the display device.
It is output as display image data D.

Next, the operation of the phase correction section 4 will be described. The target reception signal RS and the initial distance RG between the radar and the target center of gravity, the distance of which has been corrected by the time input from the distance correction unit 3, are stored in the buffer circuit 8, and the initial reception signal RS and the initial distance between the radar and the target center of gravity are stored. It is output as the target reception signal GS at the distance RG. The target reception signal GS at the initial distance RG between the radar and the target center of gravity is frequency-analyzed in a small section in the time direction by the divided frequency analysis circuit 9, and the obtained maximum frequency value and amplitude waveform are detected by the maximum amplitude value detection circuit 10. After detecting the frequency at which the amplitude value becomes maximum as the reference point frequency, it is output to the smoothing circuit 11. The smoothing circuit 11 smoothes the locus of the reference point frequency in the time direction, and calculates the phase correction amount calculating circuit 1 from the smoothed locus.
In step 2, the amount of phase correction is calculated. The phase correction circuit 13 uses the phase correction amount calculated by the phase correction amount calculation circuit 12 to correct the phase of the target reception signal RS output from the buffer circuit 8 and corrected for the distance shift due to time. The frequency analysis unit 5 determines the corrected target reception signal RD as
Output to

Further, the phase correction section 4 will be described with reference to FIG. FIG. 8 is a diagram illustrating a processing method of the phase correction unit 4.
The target reception signal RS whose distance deviation due to time has been corrected is represented by S
_{i, j} (where i is the range bin number, j is the pulse hit number, and i, j are natural numbers), and the range bin number where the initial distance RG between the radar and the target center of gravity is defined as r, the radar and the target center of gravity are defined. The target reception signal GS at an initial distance RG from the target reception signal RG is represented as S _{r, j,} and a waveform as shown in FIG. 8A is obtained. S _{r, j} hand, when the frequency analysis in small sections to piecewise frequency analysis circuit 9 time direction (pulse hit direction) waveform as shown in FIG. 8 (b) is obtained, the frequency f _m and an amplitude A ^k _m (Where k is a division frequency analysis number, m is a frequency bin number, and k and m are natural numbers) are represented by “Equation 1”.

[0007]

(Equation 1)

[0008] In the amplitude maximum detection circuit 10 for each division frequency analysis number k, the amplitude A ^k _m detects the frequency at which the maximum value to it as a reference point frequency f ^k, the time t _k
The relationship between and the reference point frequency f ^k is as shown in the plot of FIG. To plot in Figure smoothing circuit 11 8 (c), the smoothing waveform shown by the solid line shown in FIG. 8 (c) is obtained, the relationship between the time t _k and the frequency f ^'k' number 2 ' It is represented by

[0009]

(Equation 2)

The phase correction amount calculation circuit 12 calculates the phase correction amount _Wj by "Equation 3".

[0011]

(Equation 3)

The phase correction circuit 13 corrects the phase of S _{i, j} by “Equation 4” using the phase correction amount W _j . However, the target reception signal RD whose phase shift due to time has been corrected is represented by S ′.
Define as _{i, j} .

[0013]

(Equation 4)

[0014]

In the conventional radar signal processing apparatus as described above, the frequency and amplitude waveforms after the divisional frequency analysis have multiple peaks, and the position of the peak at which the amplitude value is maximum is located at every time. If such fluctuates greatly, it is impossible to calculate an accurate phase compensation amount unsteady detected reference point frequency, the image is blurred, there is a problem that blurred.

[0015] The present invention has been made to solve the above problem, it is impossible to calculate an accurate phase compensation amount unsteady detected reference point frequency, the image is blurred, that is disappear, It is an object of the present invention to obtain a radar signal processing device that prevents the occurrence of a radar signal.

[0016]

In the radar signal processing apparatus according to the present invention, the phase correction unit stores a target reception signal corrected by the distance correction unit and an initial distance between the radar and the target center of gravity. A divided frequency analysis circuit that analyzes the frequency of a target reception signal at an initial distance between the radar output from the buffer circuit and the target center of gravity in a small section in the time direction, and a waveform of the frequency and amplitude obtained by the divided frequency analysis circuit. An interpolation circuit for interpolating in the frequency direction, a frequency setting circuit for setting a reference frequency within a frequency region allowed for the frequency and amplitude waveforms, and a frequency and amplitude waveform starting from the start point of the allowed frequency region. A first integration circuit for calculating an area by integrating up to a frequency set by the frequency setting circuit, and a first integration circuit for calculating the area when the area calculated by the first integration circuit is halved. A first area center calculating circuit for calculating a wave number, a second integrating circuit for calculating an area by integrating the frequency and amplitude waveforms from the frequency set by the frequency setting circuit to an end point of an allowable frequency region; A second area center calculation circuit for calculating a frequency when the area calculated by the second integration circuit is halved, a frequency calculated by the first area center calculation circuit, and the second area A center frequency detection circuit that detects the center frequency of the frequency calculated by the center calculation circuit as a reference point frequency, and a smoothing circuit that smoothes a locus in the time direction of the reference point frequency detected by the center frequency detection circuit, A phase correction amount calculating circuit for calculating a phase correction amount from a trajectory of the reference point frequency smoothed by the smoothing circuit in the time direction, and a phase correction amount calculated by the phase correction amount calculating circuit. Te is obtained constituted by a phase correction circuit for correcting the phase of the target received signal output from the buffer circuit.

Further, a data extracting circuit for extracting data on the frequency and amplitude waveforms interpolated by the interpolating circuit in the phase correction section, and a threshold setting circuit for setting a threshold necessary for extracting data by the data extracting circuit Is provided.

Further, the phase correction section is provided with a power calculation circuit for calculating a power of each amplitude value for the frequency and amplitude waveforms interpolated by the interpolation circuit.

The phase correction unit calculates a power of each amplitude value for the frequency and amplitude waveforms interpolated by the interpolation circuit, and a power of the frequency and amplitude calculated by the power calculation circuit. A data extracting circuit for extracting data on a waveform and a threshold setting circuit for setting a threshold necessary for extracting data by the data extracting circuit are provided.

Further, a data extraction circuit for extracting data on the frequency and amplitude waveforms interpolated by the interpolation circuit in the phase correction section, and a threshold setting circuit for setting a threshold necessary for extracting data by the data extraction circuit And a power calculation circuit for calculating a power of each amplitude value for the frequency and amplitude waveforms cut out by the data cutout circuit.

[0021]

According to the present invention, the frequency and amplitude waveforms after the divided frequency analysis are interpolated in the frequency direction, and the interpolated waveform is integrated from the start point of the allowable frequency region to the frequency set by the frequency setting circuit. The reference frequency is the center frequency between the frequency at which the obtained area is halved and the frequency at which the area obtained by integrating from the frequency set by the frequency setting circuit to the end point of the allowable frequency region is halved Since it is detected as a point frequency, even if the frequency and amplitude waveforms are multi-peaked and the position of the peak with the largest amplitude value fluctuates greatly with time, it is hardly affected by the fluctuation, and the reference point is stable. The frequency can be detected, and blur and blur of the image can be removed.

Further, since the frequency and amplitude waveforms after the division frequency analysis are interpolated in the frequency direction and the interpolated waveform is cut out based on the set threshold value, unnecessary noise components below the threshold value can be removed. The waveform obtained in this way is cut out from the frequency at which the area obtained by integrating from the starting point of the cut-out frequency domain to the frequency set by the frequency setting circuit becomes half, and the frequency set by the frequency setting circuit The center frequency of the frequency at which the area obtained by integrating up to the end point of the frequency domain that is obtained by half is detected as the reference point frequency, so that the frequency and amplitude waveforms are multi-peaked and the amplitude value is the maximum. Even when the position of a peak fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and blur and blur of an image can be removed.

Further, since the waveform of the frequency and the amplitude after the division frequency analysis is interpolated in the frequency direction and the power of each amplitude value is calculated for the interpolated waveform, the S / N ratio can be improved. The frequency obtained when the area obtained by integrating the waveform obtained in this way from the start point of the allowable frequency region to the frequency set by the frequency setting circuit is halved, and the frequency set by the frequency setting circuit Since the center frequency with the frequency at which the area obtained by integrating up to the end point of the allowable frequency region is halved is detected as the reference point frequency, the waveform of the frequency and amplitude is multi-peak, and the amplitude value is Even when the position of the maximum peak fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and blur and blur of the image can be removed.

Further, since the waveform of the frequency and the amplitude after the divided frequency analysis is interpolated in the frequency direction and the power of each amplitude value is calculated for the interpolated waveform, the S / N ratio can be improved. Furthermore, since the power-calculated waveform is cut out based on the set threshold value, unnecessary noise components below the threshold value can be removed. The waveform obtained in this way is cut out from the frequency at which the area obtained by integrating from the starting point of the cut-out frequency domain to the frequency set by the frequency setting circuit becomes half, and the frequency set by the frequency setting circuit The center frequency of the frequency at which the area obtained by integrating up to the end point of the frequency domain that is obtained by half is detected as the reference point frequency, so that the frequency and amplitude waveforms are multi-peaked and the amplitude value is the maximum. Even when the position of a peak fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and blur and blur of an image can be removed.

Further, since the frequency and amplitude waveforms after the division frequency analysis are interpolated in the frequency direction and the interpolated waveform is cut out based on the set threshold value, unnecessary noise components below the threshold value can be removed. Furthermore, since the power of each amplitude value is calculated for the cut-out waveform, the calculation amount can be reduced and the S / N ratio can be improved. The waveform obtained in this way is cut out from the frequency at which the area obtained by integrating from the starting point of the cut-out frequency domain to the frequency set by the frequency setting circuit becomes half, and the frequency set by the frequency setting circuit The center frequency of the frequency at which the area obtained by integrating up to the end point of the frequency domain that is obtained by half is detected as the reference point frequency, so that the frequency and amplitude waveforms are multi-peaked and the amplitude value is the maximum. Even when the position of a peak fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and blur and blur of an image can be removed.

[0026]

【Example】

Embodiment 1 FIG. 1 shows an embodiment of the phase correction section of the present invention in the radar signal processing device shown in FIG. In the figure, 4, RS, RG and RD are the same as in FIGS. In the drawing, 8, 9, 11, 12, 13 and GS are the same as those in FIG. 14 is a division frequency analysis circuit 9
Interpolation circuit for interpolating the frequency and amplitude waveforms obtained in the above in the frequency direction, 15 is a frequency setting circuit for setting a reference frequency within a frequency region allowed for the frequency and amplitude waveforms, and 16 is a frequency and amplitude The first integration circuit 17 calculates the area by integrating the waveform from the start point of the allowable frequency region to the frequency set by the frequency setting circuit 15, and the area calculated by the first integration circuit 16 is halved. A first area center calculating circuit for calculating the frequency at the time, a second for calculating the area by integrating the frequency and amplitude waveforms from the frequency set by the frequency setting circuit 15 to the end point of the allowable frequency region. An integrating circuit 19 is a second area center calculating circuit for calculating a frequency when the area calculated by the second integrating circuit 18 is halved, and 20 is a first area center calculating circuit 17
Is a center frequency detection circuit that detects the center frequency between the frequency calculated in step (a) and the frequency calculated in the second area center calculation circuit 19.

Next, the operation of the phase corrector 4 configured as shown in FIG. 1 will be described. The target reception signal R in which the distance shift due to the time input from the distance correction unit 3 has been corrected.
S and the initial distance RG between the radar and the target center of gravity are stored in the buffer circuit 8, and output as the target reception signal RS and the target reception signal GS at the initial distance RG between the radar and the target center of gravity. The target reception signal GS at the initial distance RG between the radar and the target center of gravity is frequency-analyzed in a small section in the time direction by the divided frequency analysis circuit 9, and is interpolated in the frequency direction by the interpolation circuit 14. The first integration circuit 16 calculates the area by integrating the waveform interpolated by the interpolation circuit 14 from the start point of the allowable frequency region to the frequency set by the frequency setting circuit 15. The second integration circuit 18 calculates the area by integrating the waveform interpolated by the interpolation circuit 14 from the frequency set by the frequency setting circuit 15 to the end point of the allowable frequency region. The frequency setting circuit 15 sets a reference frequency in an allowable frequency range, such as a frequency at which the amplitude value of the waveform of the frequency and the amplitude is maximized and a center frequency of the frequency range. The first area center calculation circuit 17 calculates the frequency when the area calculated by the first integration circuit 16 becomes half, and the second area center calculation circuit 19 calculates the frequency by the second integration circuit 18. Calculate the frequency when the area becomes half.

The center frequency detection circuit 20 detects the center frequency of the frequency calculated by the first area center calculation circuit 17 and the center frequency calculated by the second area center calculation circuit 19 as a reference point frequency, and then performs smoothing. Output to the circuit 11. The smoothing circuit 11 smoothes the locus of the reference point frequency in the time direction, and calculates a phase correction amount calculating circuit 12 from the smoothed locus.
Is used to calculate the phase correction amount. The phase correction circuit 13 uses the phase correction amount calculated by the phase correction amount calculation circuit 12 to correct the phase of the target reception signal RS output from the buffer circuit 8 and corrected for the distance shift due to time. The signal is output to the frequency analysis unit 5 as the corrected target reception signal RD.

Next, the phase corrector 4 configured as shown in FIG. 1 will be described with reference to FIGS. FIG. 8 is a diagram illustrating a processing method of the phase correction unit 4, and FIG. 9 is a diagram illustrating a waveform after the segmented frequency analysis and a waveform after the data interpolation. The target reception signal RS whose distance deviation due to time has been corrected is represented by S _{i, j} (where i
Is a range bin number, j is a pulse hit number, and i and j are natural numbers. If the range bin number where the initial distance RG between the radar and the target center of gravity exists is defined as r, the target reception signal GS at the initial distance RG between the radar and the target center of gravity becomes S
_{r, j,} and a waveform as shown in FIG. 8A is obtained. S
FIG. 8 (b) shows that the divided frequency analysis circuit 9 performs frequency analysis on small sections in the time direction (pulse hit direction) for _{r and j} .
Waveform is obtained as the relation (k is here divided frequency analysis number, m is a frequency bin number, k, m is a natural number.) Of the frequency f _m and an amplitude A ^k _m tables in "Number 1" Is done.

The frequency f at each divisional frequency analysis number k
_m and the waveform of the amplitude A ^k _m is expressed as shown in FIG. 9 (a), interpolated in the frequency direction is waveform as shown in FIG. 9 (b) is obtained by the interpolation circuit 14. Here, when the obtained waveform is integrated from the start point f _{1 of the} frequency region permitted by the first integration circuit 16 to the frequency c _k set by the frequency setting circuit 15, the area U _k is calculated by “Equation 5”. You.

[0031]

(Equation 5)

The obtained waveform is converted to a second integrating circuit 18.
By integrating from the frequency _ck set by the frequency setting circuit 15 to the end point f ₁ of the allowable frequency region, the area V _k is calculated by “Equation 6”.

[0033]

(Equation 6)

The first area center calculation circuit 17 calculates the area U _k
Is calculated so as to satisfy “Equation 7”, and the frequency at that time is _defined as X _k .

[0035]

(Equation 7)

The second area center calculating circuit 19 calculates the area V _k
Is calculated so as to satisfy “Equation 8”, and the frequency at that time is _defined as Y _k .

[0037]

(Equation 8)

The center frequency detection circuit 20 calculates the reference point frequency f ^k by using “Expression 9” using the frequency X _k and the frequency Y _k .

[0039]

(Equation 9)

The relationship between the time t _k and the reference point frequency f ^k is shown in FIG.
Look like the plot of (c), the smoothing circuit 11 smoothes the waveform shown by the solid line shown in FIG. 8 (c) is obtained, the relationship between the time t _k and the frequency f ^'k' number 2 ' It is represented by

The phase correction amount calculation circuit 12 calculates the phase correction amount W
_j is calculated by “Equation 3”. The phase correction circuit 13 _calculates S _{i, j}
It is corrected by "Number 4" by using a phase correction amount W _j of the phase.
However, the target reception signal R in which the phase shift due to time is corrected
D is defined as S ′ _{i, j} .

Embodiment 2 In the embodiment shown in FIG. 2, immediately after the interpolation circuit 14 in the first embodiment, a data extraction circuit 21 for extracting data on the frequency and amplitude waveforms interpolated by the interpolation circuit 14, Is provided with a threshold setting circuit 22 for setting a threshold necessary for cutting out. According to such an embodiment, since the interpolated frequency and amplitude waveforms are cut out based on the set threshold value, unnecessary noise components below the threshold value can be removed.

Next, the operation of the phase corrector 4 configured as shown in FIG. 2 will be described. The target reception signal R in which the distance shift due to the time input from the distance correction unit 3 has been corrected.
S and the initial distance RG between the radar and the target center of gravity are stored in the buffer circuit 8, and output as the target reception signal RS and the target reception signal GS at the initial distance RG between the radar and the target center of gravity. The target reception signal GS at the initial distance RG between the radar and the target center of gravity is frequency-analyzed in a small section in the time direction by the divided frequency analysis circuit 9 and interpolated in the frequency direction by the interpolation circuit 14. Data is cut out for a region where the amplitude value exceeds the threshold set by the threshold setting circuit 22. In the threshold setting circuit 22, for example, a fixed threshold for setting a constant threshold between the main lobe level and the side lobe level, or a CFAR (Constant Fal) for adaptively setting a threshold.
For example, a threshold is set for each waveform after the division frequency analysis using “se Alarm Rate” or the like. First integration circuit 1
In step S6, an area is calculated by integrating the waveform extracted by the data extraction circuit 21 from the start point of the extracted frequency region to the frequency set by the frequency setting circuit 15. The second integration circuit 18 calculates the area by integrating the waveform cut out by the data cut-out circuit 21 from the frequency set by the frequency setting circuit 15 to the end point of the cut-out frequency region.
The frequency setting circuit 15 sets a reference frequency in an allowable frequency range, such as a frequency at which the amplitude value of the waveform of the frequency and the amplitude is maximized and a center frequency of the frequency range. The first area center calculation circuit 17 calculates the frequency when the area calculated by the first integration circuit 16 is reduced to half, and the second area center calculation circuit 19 calculates the area calculated by the second integration circuit 18. Calculate the frequency at which is reduced by half. The center frequency detection circuit 20 detects the center frequency of the frequency calculated by the first area center calculation circuit 17 and the center frequency of the frequency calculated by the second area center calculation circuit 19 as a reference point frequency. Output. The smoothing circuit 11 smoothes the locus of the reference point frequency in the time direction, and calculates the phase correction amount calculating circuit 1 from the smoothed locus.
In step 2, the amount of phase correction is calculated. The phase correction circuit 13 uses the phase correction amount calculated by the phase correction amount calculation circuit 12 to correct the phase of the target reception signal RS output from the buffer circuit 8 and corrected for the distance shift due to time. The frequency analysis unit 5 determines the corrected target reception signal RD as
Output to

Next, the phase corrector 4 configured as shown in FIG. 2 will be described with reference to FIGS. FIG. 10 is a diagram illustrating a waveform after the data interpolation is performed on the waveform. Waveform of the frequency f _m and an amplitude A ^k _m at each division frequency analysis number k is expressed as in FIG. 9 (a), the interpolation circuit 1
4, a waveform as shown in FIG. 9B is obtained, and each amplitude value is set by the data cutout circuit 21 to the threshold value set by the threshold value setting circuit 22 (for example, the dashed line u in FIG. 9B). ) Beyond the frequency range [a _K , b _k ] (where a
_k represents the start point of the frequency domain, and b _k represents the end point of the frequency domain. When the data is cut out for ()), a waveform as shown in FIG. 10 is obtained. Here, when the obtained waveform is integrated by the first integration circuit 16 from the start point a _k of the frequency domain to the frequency c _k set by the frequency setting circuit 15, the area U _k is calculated by “Equation 10”.

[0045]

(Equation 10)

The obtained waveform is converted to a second integrating circuit 18.
When integrating from the frequency c _k set by the frequency setting circuit 15 to the end point b _{k of the} frequency domain, the area V _k becomes “Equation 11”.
Is calculated.

[0047]

[Equation 11]

The first area center calculating circuit 17 calculates the area U _k
Is calculated so as to satisfy “Equation 12”, and the frequency at that time is _defined as X _k .

[0049]

(Equation 12)

The second area center calculating circuit 19 calculates the area V _k
Is calculated so as to satisfy “Equation 8”, and the frequency at that time is _defined as Y _k .

The center frequency detecting circuit 20 calculates the reference point frequency f ^k by using “Equation 9” using the frequency X _k and the frequency Y _k .

Embodiment 3 In the embodiment shown in FIG. 3, immediately after the interpolation circuit 14 in the first embodiment, a power calculation for calculating the power of each amplitude value for the frequency and amplitude waveforms interpolated by the interpolation circuit 14 is performed. A circuit 23 is provided. According to such an embodiment, since the power of each amplitude value is calculated for the interpolated frequency and amplitude waveforms, the S / N ratio can be improved.

Next, the operation of the phase corrector 4 configured as shown in FIG. 3 will be described. The target reception signal R in which the distance shift due to the time input from the distance correction unit 3 has been corrected.
S and the initial distance RG between the radar and the target center of gravity are stored in the buffer circuit 8, and output as the target reception signal RS and the target reception signal GS at the initial distance RG between the radar and the target center of gravity. The target reception signal GS at the initial distance RG between the radar and the target center of gravity is subjected to frequency analysis in a small section in the time direction by the divided frequency analysis circuit 9, interpolated in the frequency direction by the interpolation circuit 14, and A power of the amplitude value is calculated. The first integration circuit 16 integrates the waveform calculated by the exponentiation calculation circuit 23 from the start point of the allowable frequency region to the frequency set by the frequency setting circuit 15 to calculate the area. The second integrating circuit 18 calculates the area by integrating the waveform calculated by the exponentiation calculating circuit 23 from the frequency set by the frequency setting circuit 15 to the end point of the allowable frequency region. The frequency setting circuit 15 sets a reference frequency in an allowable frequency range, such as a frequency at which the amplitude value of the waveform of the frequency and the amplitude is maximized and a center frequency of the frequency range. The first area center calculation circuit 17 calculates the frequency when the area calculated by the first integration circuit 16 is reduced to half, and the second area center calculation circuit 19 calculates the area calculated by the second integration circuit 18. Calculate the frequency at which is reduced by half. The center frequency detection circuit 20 detects the center frequency of the frequency calculated by the first area center calculation circuit 17 and the center frequency of the frequency calculated by the second area center calculation circuit 19 as a reference point frequency. Output. The smoothing circuit 11 smoothes the locus of the reference point frequency in the time direction, and the phase correction amount calculating circuit 12 calculates the phase correction amount from the smoothed locus. The phase correction circuit 13 uses the phase correction amount calculated by the phase correction amount calculation circuit 12 to correct the phase of the target reception signal RS output from the buffer circuit 8 and corrected for the distance shift due to time. Corrected target received signal R
D is output to the frequency analysis unit 5.

Next, the phase correcting section 4 configured as shown in FIG. 3 will be described with reference to FIGS. FIG. 11 is a diagram showing the waveform after the exponentiation calculation. Waveform of the frequency f _m and an amplitude A ^k _m at each division frequency analysis number k is 9
When the interpolation circuit 14 interpolates in the frequency direction, a waveform as shown in FIG. 9B is obtained. When the exponentiation circuit 23 calculates the power of each amplitude value, a waveform as shown in FIG. 11 is obtained. Is obtained. Here, when the obtained waveform is integrated from the start point f _{1 of the} frequency region permitted by the first integration circuit 16 to the frequency c _k set by the frequency setting circuit 15, the area U _k is calculated by “Equation 13”. You.

[0055]

(Equation 13)

The obtained waveform is converted to a second integrating circuit 18.
By integrating from the frequency c _k set by the frequency setting circuit 15 to the end point f ₁ of the allowable frequency region, the area V _k is calculated by “Equation 14”.

[0057]

[Equation 14]

The first area center calculating circuit 17 calculates the area U _k
Is calculated so as to satisfy “Equation 15”, and the frequency at that time is _defined as X _k .

[0059]

(Equation 15)

The second area center calculating circuit 19 calculates the area V _k
Is calculated to satisfy “Equation 16”, and the frequency at that time is _defined as Y _k .

[0061]

(Equation 16)

The center frequency detecting circuit 20 calculates the reference point frequency f ^k by using “Equation 9” using the frequency X _k and the frequency Y _k .

Fourth Embodiment In the embodiment shown in FIG. 4, immediately after the interpolation circuit 14 in the first embodiment, a power calculation is performed to calculate the power of each amplitude value for the frequency and amplitude waveforms interpolated by the interpolation circuit 14. A circuit 23, a data extracting circuit 21 for extracting data on the power and the waveform of the frequency and the amplitude calculated by the exponentiation calculating circuit 23, and a threshold setting circuit 22 for setting a threshold necessary for extracting the data are provided. According to such an embodiment, since the power of each amplitude value is calculated for the interpolated frequency and amplitude waveforms, the S / N ratio can be improved. Furthermore, since the power-calculated waveform is cut out based on the set threshold value, unnecessary noise components below the threshold value can be removed.

Next, the operation of the phase corrector 4 configured as shown in FIG. 4 will be described. The target reception signal R in which the distance shift due to the time input from the distance correction unit 3 has been corrected.
S and the initial distance RG between the radar and the target center of gravity are stored in the buffer circuit 8, and output as the target reception signal RS and the target reception signal GS at the initial distance RG between the radar and the target center of gravity. The target reception signal GS at the initial distance RG between the radar and the target center of gravity is subjected to frequency analysis in a small section in the time direction by the divided frequency analysis circuit 9, interpolated in the frequency direction by the interpolation circuit 14, and The power of the amplitude value is calculated, and data is cut out by the data cutout circuit 21 for an area where each amplitude value exceeds the threshold set by the threshold setting circuit 22. In the threshold setting circuit 22, for example, a fixed threshold for setting a constant threshold between the main lobe level and the side lobe level, or a CFAR (Constant Fal) for adaptively setting a threshold.
For example, a threshold is set for each waveform after each section frequency analysis by using (seAlarm Rate) or the like. First integration circuit 16
In the above, the area cut out from the start point of the frequency region cut out from the waveform cut out by the data cutout circuit 21 to the frequency set by the frequency setting circuit 15 is calculated. The second integration circuit 18 calculates the area by integrating the waveform cut out by the data cut-out circuit 21 from the frequency set by the frequency setting circuit 15 to the end point of the cut-out frequency region. The frequency setting circuit 15 sets a reference frequency in an allowable frequency range, such as a frequency at which the amplitude value of the waveform of the frequency and the amplitude is maximized and a center frequency of the frequency range. In the first area center calculation circuit 17, the first
The frequency when the area calculated by the integrating circuit 16 is halved is calculated, and the second area center calculating circuit 19 calculates the frequency when the area calculated by the second integrating circuit 18 is halved.

The center frequency detection circuit 20 detects the center frequency of the frequency calculated by the first area center calculation circuit 17 and the center frequency calculated by the second area center calculation circuit 19 as a reference point frequency, and then performs smoothing. Output to the circuit 11. The smoothing circuit 11 smoothes the locus of the reference point frequency in the time direction, and the phase correction amount calculating circuit 12 calculates the phase correction amount from the smoothed locus. The phase correction circuit 13 uses the phase correction amount calculated by the phase correction amount calculation circuit 12 to correct the phase of the target reception signal RS output from the buffer circuit 8 and corrected for the distance shift due to time. The signal is output to the frequency analysis unit 5 as the corrected target reception signal RD.

Next, the phase corrector 4 configured as shown in FIG. 4 will be described with reference to FIGS. 9, 11 and 12. FIG. 12 is a diagram showing a waveform after the extraction of the power-calculated waveform. Frequency f _m at each division frequency analysis numbers k
The waveform of the amplitude A ^k _m is expressed as FIG. 9 (a), the waveform obtained as the interpolated in the frequency direction in the interpolation circuit 14 FIG. 9 (b), the a power calculating circuit 23 for amplitude values When a power is calculated, a waveform as shown in FIG. 11 is obtained. Further, a frequency region [a _K , b _k ] in which each amplitude value exceeds a threshold value (for example, a dashed line v in FIG. 11) set by the threshold value setting circuit 22 in the data extraction circuit 21 (where a _k is a frequency region) When the data is cut out at the start point and b _k indicates the end point of the frequency domain, a waveform as shown in FIG. 12 is obtained. Here, when the obtained waveform is integrated by the first integration circuit 16 from the start point a _k of the frequency domain to the frequency c _k set by the frequency setting circuit 15, the area U _k is calculated by “Equation 17”.

[0067]

[Equation 17]

The obtained waveform is converted to a second integrating circuit 18.
When integrating from the frequency c _k set by the frequency setting circuit 15 to the end point b _{k of the} frequency domain, the area V _k becomes “Equation 18”.
Is calculated.

[0069]

(Equation 18)

The first area center calculation circuit 17 calculates the area U _k
Is calculated so as to satisfy “Equation 19”, and the frequency at that time is _defined as X _k .

[0071]

[Equation 19]

The second area center calculating circuit 19 calculates the area V _k
Is calculated to satisfy “Equation 16”, and the frequency at that time is _defined as Y _k . The center frequency detection circuit 20 calculates the reference point frequency f ^k using “Expression 9” using the frequency X _k and the frequency Y _k .

Fifth Embodiment In the embodiment shown in FIG. 5, immediately after the interpolation circuit 14 in the first embodiment, a data extraction circuit 21 for extracting data on the frequency and amplitude waveforms interpolated by the interpolation circuit 14, A threshold setting circuit 22 for setting a threshold necessary for extracting the data, and a power calculation circuit 23 for calculating the power of each amplitude value for the frequency and amplitude waveforms extracted by the data extraction circuit 21. According to such an embodiment, since the interpolated frequency and amplitude waveforms are cut out based on the set threshold value, unnecessary noise components below the threshold value can be removed. Furthermore, since the power of each amplitude value is calculated for the cut-out waveform, the calculation amount can be reduced and the S / N ratio can be improved.

Next, the operation of the phase corrector 4 configured as shown in FIG. 5 will be described. The target reception signal R in which the distance shift due to the time input from the distance correction unit 3 has been corrected.
S and the initial distance RG between the radar and the target center of gravity are stored in the buffer circuit 8, and output as the target reception signal RS and the target reception signal GS at the initial distance RG between the radar and the target center of gravity. The target reception signal GS at the initial distance RG between the radar and the target center of gravity is frequency-analyzed in a small section in the time direction by the divided frequency analysis circuit 9 and interpolated in the frequency direction by the interpolation circuit 14. Data is cut out for a region where the amplitude value exceeds the threshold value set by the threshold value setting circuit 22, and the power calculation circuit 23 calculates the power of each amplitude value. In the threshold setting circuit 22, for example, a fixed threshold for setting a constant threshold between the main lobe level and the side lobe level, or a CFAR (Constant Fal) for adaptively setting a threshold.
For example, a threshold is set for each waveform after each section frequency analysis by using (seAlarm Rate) or the like. First integration circuit 16
Then, the waveform calculated by the exponentiation calculation circuit 23 is integrated from the start point of the cut-out frequency region to the frequency set by the frequency setting circuit 15 to calculate the area. Second integration circuit 1
In step 8, the area calculated by integrating the waveform calculated by the power calculation circuit 23 from the frequency set by the frequency setting circuit 15 to the end point of the frequency region cut out. The frequency setting circuit 15 sets a reference frequency in an allowable frequency range, such as a frequency at which the amplitude value of the waveform of the frequency and the amplitude is maximized and a center frequency of the frequency range.

The first area center calculating circuit 17 calculates the frequency when the area calculated by the first integrating circuit 16 is reduced to half, and the second area center calculating circuit 19 calculates the frequency by the second integrating circuit 18. The frequency at which the calculated area is halved is calculated. In the center frequency detection circuit 20, the frequency calculated by the first area center calculation circuit 17 and the second area center calculation circuit 1
After detecting the center frequency of the frequency calculated in step 9 as a reference point frequency, the frequency is output to the smoothing circuit 11. The smoothing circuit 11 smoothes the locus of the reference point frequency in the time direction, and the phase correction amount calculating circuit 12 calculates the phase correction amount from the smoothed locus. The phase correction circuit 13 uses the phase correction amount calculated by the phase correction amount calculation circuit 12 to correct the phase of the target reception signal RS output from the buffer circuit 8 and corrected for the distance shift due to time. The signal is output to the frequency analysis unit 5 as the corrected target reception signal RD.

Next, the phase correcting section 4 configured as shown in FIG. 5 will be described with reference to FIGS. 9, 10 and 12. FIG. 12 is a diagram showing a waveform after exponentiation calculation of the extracted waveform. Waveform of the frequency f _m and an amplitude A ^k _m at each division frequency analysis number k is expressed as in FIG. 9 (a), when interpolation in the frequency direction is waveform as shown in FIG. 9 (b) obtained by the interpolation circuit 14 The frequency region [a _K , b _k ] (where a _k is the frequency) where each amplitude value exceeds the threshold set by the threshold setting circuit 22 (for example, the one-dot broken line u in FIG. 9B) in the data cutout circuit 21 When the data is cut out for the start point of the area and b _k indicates the end point of the frequency area, FIG.
Is obtained. Further, when the power calculation circuit 23 calculates the power of each amplitude value, a waveform as shown in FIG. 12 is obtained. Here, when the obtained waveform is integrated by the first integration circuit 16 from the start point a _k of the frequency domain to the frequency c _k set by the frequency setting circuit 15, the area U _k is calculated by “Equation 17”.

The obtained waveform is converted to a second integrating circuit 18.
When integrating from the frequency c _k set by the frequency setting circuit 15 to the end point b _{k of the} frequency domain, the area V _k becomes “Equation 18”.
Is calculated. The first area center calculation circuit 17 calculates the area U
The frequency when _k becomes half is calculated so as to satisfy “Equation 19”, and the frequency at that time is set to X _k .

The second area center calculating circuit 19 calculates the area V _k
Is calculated to satisfy “Equation 16”, and the frequency at that time is _defined as Y _k . The center frequency detection circuit 20 calculates the reference point frequency f ^k using “Expression 9” using the frequency X _k and the frequency Y _k .

[0079]

As described above, according to the present invention, the area obtained by integrating from the starting point of the frequency domain to the frequency set by the frequency setting circuit is reduced by focusing on the area of the waveform after the divided frequency analysis. The center frequency between the time frequency and the frequency when the area obtained by integrating from the frequency set by the frequency setting circuit to the end point of the frequency domain is halved is detected as the reference point frequency. Even when the position of the peak where the waveform is multi-peak and the amplitude value is maximum fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and the image blur There is an effect that bleeding can be removed.

Further, according to the present invention, the frequency and amplitude waveforms after the divided frequency analysis are interpolated in the frequency direction, and the interpolated waveform is cut out based on the set threshold value, so that unnecessary noise components below the threshold value are removed. Can be. The waveform obtained in this way is cut out from the frequency at which the area obtained by integrating from the starting point of the cut-out frequency domain to the frequency set by the frequency setting circuit becomes half, and the frequency set by the frequency setting circuit The center frequency of the frequency at which the area obtained by integrating up to the end point of the frequency domain that is obtained by half is detected as the reference point frequency, so that the frequency and amplitude waveforms are multi-peaked and the amplitude value is the maximum. Even when the position of a peak fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and blur and blur of an image can be removed.

According to the present invention, the frequency and amplitude waveforms after the division frequency analysis are interpolated in the frequency direction, and the power of each amplitude value is calculated for the interpolated waveform, so that the S / N ratio can be improved. The frequency obtained when the area obtained by integrating the waveform obtained in this way from the start point of the allowable frequency region to the frequency set by the frequency setting circuit is halved, and the frequency set by the frequency setting circuit Since the center frequency with the frequency at which the area obtained by integrating up to the end point of the allowable frequency region is halved is detected as the reference point frequency, the waveform of the frequency and amplitude is multi-peak, and the amplitude value is Even when the position of the maximum peak fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and blur and blur of the image can be removed.

According to the present invention, the frequency and amplitude waveforms after the division frequency analysis are interpolated in the frequency direction, and the power of each amplitude value is calculated for the interpolated waveform, so that the S / N ratio can be improved. . Furthermore, since the power-calculated waveform is cut out based on the set threshold value, unnecessary noise components below the threshold value can be removed. The waveform obtained in this way is cut out from the frequency at which the area obtained by integrating from the starting point of the cut-out frequency domain to the frequency set by the frequency setting circuit becomes half, and the frequency set by the frequency setting circuit The center frequency of the frequency at which the area obtained by integrating up to the end point of the frequency domain that is obtained by half is detected as the reference point frequency, so that the frequency and amplitude waveforms are multi-peaked and the amplitude value is the maximum. Even when the position of a peak fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and blur and blur of an image can be removed.

According to the present invention, since the frequency and amplitude waveforms after the division frequency analysis are interpolated in the frequency direction and the interpolated waveform is cut out based on the set threshold, unnecessary noise components below the threshold can be removed. it can. Furthermore, since the power of each amplitude value is calculated for the cut-out waveform, the calculation amount can be reduced and the S / N ratio can be improved. The waveform obtained in this way is cut out from the frequency at which the area obtained by integrating from the starting point of the cut-out frequency domain to the frequency set by the frequency setting circuit becomes half, and the frequency set by the frequency setting circuit The center frequency of the frequency at which the area obtained by integrating up to the end point of the frequency domain that is obtained by half is detected as the reference point frequency, so that the frequency and amplitude waveforms are multi-peaked and the amplitude value is the maximum. Even when the position of a peak fluctuates greatly with time, it is hardly affected by the fluctuation, the reference point frequency can be detected stably, and blur and blur of an image can be removed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a phase correction unit according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a phase correction unit according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a phase correction unit according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a phase correction unit according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a phase correction unit according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of a radar signal processing device of the high resolution radar device.

FIG. 7 is a configuration diagram of a conventional phase correction unit.

FIG. 8 is a diagram illustrating a processing method of a phase correction unit.

FIG. 9 is a diagram showing a waveform after a divided frequency analysis and a waveform after data interpolation.

FIG. 10 is a diagram showing a waveform of a data-interpolated waveform after clipping.

FIG. 11 is a diagram showing a waveform after exponentiation calculation.

FIG. 12 is a diagram showing a waveform after a power-calculated waveform is cut out or a waveform after a power-out calculation of the cut-out waveform.

[Explanation of symbols]

Reference Signs List 1 data interface unit 2 pulse compression unit 3 distance correction unit 4 phase correction unit 5 frequency analysis unit 6 detection unit 7 display interface unit 8 buffer circuit 9 division frequency analysis circuit 10 maximum amplitude value detection circuit 11 smoothing circuit 12 phase correction amount Calculation circuit 13 Phase correction circuit 14 Interpolation circuit 15 Frequency setting circuit 16 First integration circuit 17 First area center calculation circuit 18 Second integration circuit 19 Second area center calculation circuit 20 Center frequency detection circuit 21 Data extraction circuit Reference Signs List 22 threshold setting circuit 23 exponentiation calculation circuit target reception signal input from SM radar device RS target reception signal whose distance deviation due to time has been corrected by distance correction unit 3 RG initial distance between radar and target center of gravity GS radar and target center of gravity Target reception signal RD at the initial distance RG of the Target reception signal D with phase shift corrected D Display image data

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01S 13/00-13/96

Claims (5)

(57) [Claims] A data interface unit for converting a target reception signal input from a radar device into a data format that can be internally processed; a pulse compression unit for pulse-compressing the target reception signal converted by the data interface unit; A distance correction unit that corrects a distance shift due to time of the target reception signal pulse-compressed by the pulse compression unit; a phase correction unit that corrects a phase shift due to time of the target reception signal corrected by the distance correction unit; A frequency analysis unit that separates the Doppler frequency of the target reception signal corrected by the correction unit, a detection unit that converts the frequency spectrum of the target reception signal frequency-analyzed by the frequency analysis unit into image data, and a detection unit that obtains the image data. Having a display interface unit that adjusts the interface of the displayed image data and the display to generate display image data In the signal processing device, the phase correction unit stores a target reception signal corrected by the distance correction unit and a buffer circuit that stores an initial distance between the radar and the target center of gravity, and a radar and a target center of gravity output from the buffer circuit. A division frequency analysis circuit for performing frequency analysis of a target reception signal at an initial distance in a small section in a time direction, an interpolation circuit for interpolating in the frequency direction a frequency and amplitude waveform obtained by the above-described division frequency analysis circuit, and a frequency and amplitude A frequency setting circuit for setting a reference frequency within a frequency range permitted for the waveform, and an area obtained by integrating the frequency and amplitude waveforms from the start point of the permitted frequency range to the frequency set by the frequency setting circuit. A first integration circuit for calculating, and a first area center calculation circuit for calculating a frequency when the area calculated by the first integration circuit is halved; A second integrating circuit for integrating the frequency and amplitude waveforms from the frequency set by the frequency setting circuit to the end point of the allowable frequency region to calculate an area; and calculating the area calculated by the second integrating circuit. A second area center calculating circuit for calculating the frequency when the frequency is reduced to half; a frequency calculated by the first area center calculating circuit and a center frequency of the frequency calculated by the second area center calculating circuit as a reference; A center frequency detection circuit that detects the point frequency, a smoothing circuit that smoothes a trajectory in the time direction of the reference point frequency detected by the center frequency detection circuit, and a reference point frequency that is smoothed by the smoothing circuit. A phase correction amount calculation circuit for calculating a phase correction amount from a trajectory in the time direction, and a target reception amount output from the buffer circuit using the phase correction amount calculated by the phase correction amount calculation circuit. The radar signal processing apparatus characterized by being configured by a phase correction circuit for correcting the phase of the signal. 2. A data extraction circuit for extracting data on a frequency and amplitude waveform interpolated by the interpolation circuit in the phase correction unit, and a threshold setting circuit for setting a threshold necessary for extracting data by the data extraction circuit The radar signal processing device according to claim 1, further comprising: 3. The radar signal processing according to claim 1, wherein said phase correction unit is provided with a power calculation circuit for calculating a power of each amplitude value with respect to the frequency and amplitude waveforms interpolated by said interpolation circuit. apparatus. 4. A power calculation circuit for calculating a power of each amplitude value for the frequency and amplitude waveforms interpolated by the interpolation circuit in the phase correction section, and a power of the frequency and amplitude calculated by the power calculation circuit. 2. The radar signal processing apparatus according to claim 1, further comprising a data extracting circuit for extracting data on the waveform, and a threshold setting circuit for setting a threshold necessary for extracting data by the data extracting circuit. 5. A data extraction circuit for extracting data on a frequency and amplitude waveform interpolated by the interpolation circuit in the phase correction section, and a threshold setting circuit for setting a threshold necessary for extracting data by the data extraction circuit 2. The radar signal processing apparatus according to claim 1, further comprising a power calculation circuit for calculating a power of each amplitude value for the waveform of the frequency and the amplitude extracted by the data extraction circuit.