KR101813390B1 - Method and Apparatus for processing hybrid Medium Pulse Repetition Frequency signal using frequency tunable and fixable scheme - Google Patents

Abstract

The present invention relates to an ultra-high frequency radar system technology. More particularly, the present invention relates to a method and an apparatus which can design a waveform and process a signal to improve detecting and/or tracking performance on a target in an ultra-high frequency radar system. According to the present invention, a limit and a problem of the existing technology of a calculation burden of a signal processor, and a difficulty in high resolution distance information acquisition due to a difficulty in accurate speed correction can be solved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid MPRF signal processing method and apparatus using a frequency variable and a fixed method,

The present invention relates to a very high frequency radar system technique, and more particularly, to a method and apparatus capable of waveform design and signal processing for improving detection and / or tracking performance of a target in a very high frequency radar system.

In general, in order to improve target detection / tracking performance in the presence of clutter, a medium pulse repetition frequency (MPRF) waveform is operated and target information is extracted from the obtained distance and / or Doppler map. However, as the distance between the target and the target becomes closer, the effect of the angular glint, which is caused by the interference due to the multiple scattering point of the target, becomes larger, thereby degrading the accuracy of the angle tracking accuracy. High resolution distance information is needed to reduce this angular glint effect.

As shown in FIG. 1, a technique for improving the distance resolution in the MPRF method can be roughly classified into a frequency fixing method and a frequency variable method. In the frequency fixing method, a center frequency of a linear frequency modulation (LFM) And the bandwidth of the LFM signal is increased in a fixed state.

On the other hand, the frequency variable method is a technique of increasing the total change bandwidth while changing the center frequency of the LFM signal although the bandwidth of the LFM signal is not large.

In the case of using the frequency fixing scheme, the sampling frequency of the ADC (Analog-to-Digital Converter) of the signal processor must be increased as the bandwidth of the transmission signal increases in order to perform the pulse compression process in the signal processor, There is a limitation in designing the bandwidth of the transmission signal to be large.

In addition, when the frequency variable method is used, there is a problem that it is difficult to obtain a normal HRR (High Range Resolution) profile by receiving a signal in which the fluctuation phase due to the frequency variation and the fluctuation phase due to the target velocity are combined with respect to the moving target.

In order to solve this problem, it is necessary to correct the phase components caused by the target velocity. In addition to knowing the target distance / velocity information correctly, the target information can not be distinguished in the case of mixed target / non-target signals. There is a problem that it can not be applied.

1. An apparatus and method for measuring a time delay and a pulse width of a linear frequency modulation waveform having a continuous phase generated by a very high frequency synthesizer,

1. Kim, Tae-Hyung et al., "Real-time PRF Selection for Navigation / Tracking in Aircraft Radar Using MPRF Waveform", Journal of Korea Electromagnetic Engineering Society, Vol. 25, No.10, October 2014, pp.1050-1061

Disclosure of Invention Technical Problem [8] The present invention has been proposed in order to solve the above problems, and provides a hybrid MPRF signal processing method and apparatus capable of designing a bandwidth of a transmission signal with a reduced calculation burden. .

It is another object of the present invention to provide a hybrid MPRF signal processing method and apparatus capable of obtaining a HRR (High Range Resolution) profile simply.

In order to achieve the above object, the present invention provides a hybrid MPRF (Medium Pulse Repetition Frequency) signal processing method capable of designing a bandwidth of a transmission signal with a reduced calculation burden.

The hybrid MPRF signal processing method includes:

(a) acquiring a first received signal through a frequency fixing scheme for a radar signal received using a radar antenna;

(b) generating a distance-Doppler map using the first received signal;

(c) detecting and recognizing target and non-target information in the distance-Doppler map;

(d) obtaining a second received signal for the radar signal via a frequency varying scheme; And

(e) correcting the recognized target information in the second received signal to generate high resolution distance information for the target.

In this case, the step (e) may further include performing speed correction on the high resolution distance information.

In addition, the frequency fixing method uses a fixed center frequency.

In addition, the frequency variable method may be a frequency variable method based on a Kostas code in which center frequency step intervals are not changed.

The hybrid MPRF signal processing method may further include extracting angle information from the high resolution distance information after step (e).

In addition, the frequency varying method and the frequency fixing method may be alternately used.

In addition, the target and non-target information may be classified into speed information.

In addition, the correction is performed through speed correction, and a target peak point of the target information is used.

On the other hand, another embodiment of the present invention is a radar antenna comprising: a radar antenna; A receiving unit for generating a radar signal from the radar antenna; And acquiring a first received signal for the radar signal through a frequency locking scheme, generating a distance-Doppler map using the first received signal, detecting target and non-target information in the distance-Doppler map, And a signal processing unit for acquiring a second received signal with respect to the radar signal through a frequency variable method and correcting the recognized target information in the second received signal to generate high resolution distance information for the target It is possible to provide a hybrid MPRF signal processing apparatus using a frequency variable and fixed system.

 According to the present invention, it is possible to solve the limitations and problems of the prior art which are difficult to obtain high-resolution distance information due to burden of signal processor operation and difficulty in accurate speed correction.

As another effect of the present invention, it is possible to simultaneously extract the high-resolution distance information on the target as well as the distance / Doppler map through hybrid MPRF (Medium Pulse Repetition Frequency) waveform and signal processing, thereby minimizing the influence of angular glint .

In addition, another advantage of the present invention is that the angle tracking accuracy performance can be improved remarkably.

FIG. 1 is a conceptual diagram of a frequency fixing method and a frequency variable method for improving distance resolution in a conventional MPRF (Medium Pulse Repetition Frequency) method.
FIG. 2A is a configuration block diagram of a hybrid MPRF signal processing apparatus 200 according to an embodiment of the present invention.
2B is a detailed configuration diagram of the signal processing unit 230 shown in FIG. 2A.
FIG. 3 is a conceptual diagram illustrating signal processing according to the MPRF frequency fixing scheme in a receiver in general.
4 is a conceptual diagram illustrating a process of processing a signal processed in the receiving unit of FIG. 3 in a signal processing unit.
5 is a waveform diagram showing a phase characteristic of a received signal in a frequency variable system.
6 is a hybrid MPRF waveform diagram using a wavenumber variable and fixed method according to an embodiment of the present invention.
7 is a conceptual diagram illustrating a hybrid MPRF signal processing procedure using a wavenumber variable and fixed method according to an embodiment of the present invention.
8 is a waveform diagram showing a frequency variation method based on a general Kostas code.
FIG. 9 is a characteristic graph of a frequency variation method based on a general Kostas code.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

Hereinafter, a hybrid MPRF signal processing method and apparatus using a frequency variable and fixed scheme according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

One embodiment of the present invention proposes a hybrid waveform that is interleaved with a Costas code-based frequency variable scheme and a fixed frequency scheme using a fixed center frequency. In addition, a distance-Doppler map is generated using the received signal obtained through the frequency fixing method, target information is detected / recognized in the distance-Doppler map, and target velocity information is added to the received signal obtained through the frequency variable method To generate an HRR profile of only the target signal, and extracting the angular information therefrom, thereby reducing the influence of the angular glint .

FIG. 2A is a configuration block diagram of a hybrid MPRF (Medium Pulse Repetition Frequency) signal processing apparatus 200 according to an embodiment of the present invention. Referring to FIG. 2A, the hybrid MPRF signal processing apparatus 200 includes a radar antenna 210, a receiving unit 220 receiving a signal from the radar antenna 210 and generating a radar signal, A signal processing unit 230 for generating high resolution distance information through a hybrid MPRF (Medium Pulse Repetition Frequency) using a high resolution distance information, a total time 240 for outputting high resolution distance information, and the like.

2B is a detailed configuration diagram of the signal processing unit 230 shown in FIG. 2A. Referring to FIG. 2B, the signal processing unit 230 includes a first reception signal obtaining unit 231-1 for obtaining a first reception signal through the frequency fixing method with respect to the radar signal, A distance-Doppler map generation unit 233 for generating a distance-Doppler map, a target detection recognition unit 235 for detecting and recognizing the target information in the distance-Doppler map, a second reception A distance information generator 237 for generating high resolution distance information on the target by correcting the target information recognized in the second reception signal, and the like, .

Of course, the signal processing unit 230 may extract the angle information from the distance information to reduce the influence of the angular glint. Generally, multiple scattering points of a target are distributed over a wide range of regions. When high resolution distance information is used, these multiple scattering points can be distinguished in the respective distance regions. Thus, multiple scattering point mutual interference can be reduced and angular glint effects can be reduced.

FIG. 3 is a conceptual diagram illustrating signal processing according to the MPRF frequency fixing scheme in a receiver in general. Referring to FIG. 3, the receiver performs frequency down conversion, gain conversion, and band pass filter (BPF) on the radar signals Tx_MPRF and Rx_MPRF in the coherent processing interval.

4 is a conceptual diagram illustrating a process of processing a signal processed in the receiving unit of FIG. 3 in a signal processing unit. Referring to FIG. 4, the signal processing unit converts an analog radar signal into a digital radar signal through an ADC (Analog-Digital Converter), and then performs frequency down conversion, decimation, I / Q component extraction, and distance gating do. In the signal processing unit, complex pulse compression, complex Doppler filtering, and non-coherent integration (NCI) are performed. At this time, in order to perform the pulse compression process, the sampling frequency of the analog-to-digital converter (ADC) of the signal processing unit must be increased as the bandwidth of the transmission signal increases. There is a limitation in designing the bandwidth of the transmission signal to be large because the computation burden of processing the digital reception data to be processed in real time is increased.

In the signal processing section, target detection, side-leaf signal identification, velocity tracking, distance tracking, and angle extraction are performed.

)을 보정해 주어야 하는데, 표적 거리/속도 정보를 정확히 알아야 될 뿐만 아니라 표적/비표적 신호가 혼재된 상황에서는 표적 정보를 구분할 수 없기 때문에 단순한 보정 방안을 적용하기가 불가능하다는 단점이 있다.5 is a waveform diagram showing a phase characteristic of a received signal in a frequency variable system. Referring to FIG. 5, it is difficult to obtain a normal HRR (High Range Resolution) profile by receiving signals 510 and 520 in which a fluctuation phase due to a frequency variation and a fluctuation phase due to a target velocity are combined with respect to a moving target. To solve this problem, the phase components induced by the target velocity (

In addition to knowing the target distance / speed information accurately, it is impossible to apply the simple correction method because the target information can not be distinguished in the situation where the target / non-target signals are mixed.

One embodiment of the present invention implements a hybrid MPRF processing method using a frequency variable method and a frequency fixing method to solve the general disadvantages of FIGS.

6 is a hybrid MPRF waveform diagram using a wavenumber variable and fixed method according to an embodiment of the present invention. Referring to FIG. 6, the hybrid MPRF waveform is a configuration in which a variable frequency system based on a Costas code and a frequency fixed system using a fixed center frequency are mutually arranged. Further, in the case of odd first time (# 1), third time (# 3), fifth time (# 5), ..., the waveform of the frequency variable system is arranged, # 2), the fourth time (# 4), ..., the waveform of the frequency fixing scheme is arranged. That is, the frequency variable system and the frequency fixed system are used alternately. Of course, in this case, the frequency step interval of the transmission signal may be the same.

7 is a conceptual diagram illustrating a hybrid MPRF signal processing procedure using a wavenumber variable and fixed method according to an embodiment of the present invention. Referring to FIG. 7, a first received signal is obtained for a radar signal received using a radar antenna (210 of FIG. 2A) through a frequency fixing scheme, and a distance-Doppler map RD -Map) (step S710). In addition, the distance-Doppler map is a result of three-dimensionally expressing the distance and relative speed characteristics of the received signal by collecting Doppler frequency characteristics of a signal received at a specific distance. First, a distance-of-interest region is defined through a distance gating process. Then, a distance-Doppler map is generated by collecting a received signal having a relatively long distance delay on the basis of each transmission signal with respect to the region of interest, .

Then, the target information is detected and recognized in the distance-Doppler map (step S720). In addition, the distance-Doppler map distinguishes the target (V _T ) from non-target information. That is, target and non-target information can be classified into speed information. Thus, it can be used to distinguish a target from a non-target signal in a distance-Doppler map.

When the target information is recognized, a second received signal is acquired for the radar signal through a frequency variable method, and the recognized target information is corrected for the second received signal to generate high resolution distance information for the target (step S730) . In addition, as shown in FIG. 9, when the phase correction is performed using the target speed information recognized for the second received signal by the characteristic of the variable method based on the Costas code, only the target signals are seen to be matched, Non-target signals with different velocities are not visible due to the velocity error.

Thereafter, the angle information is extracted from the high resolution distance information to reduce the influence of the angular glint (step S740). In general, the angle information extraction can be extracted by a mono-pulse system using the SUM channel and the DELTA channel. From the high-resolution distance information, angle information of the received signal can be extracted using the received signals of the SUM channel and the DELTA channel corresponding to the target peak point. If the high resolution distance information is used, the mutual scattering point mutual interference is reduced, The angular information with reduced angular glint influence is extracted.

8 is a waveform diagram showing a frequency variation method based on a general Costas code. Referring to FIG. 8, the Costas code-based frequency variable scheme is an operation concept in which center frequency step intervals of transmission signals are unequally changed, and there is a characteristic that a distance / speed coupling phenomenon does not occur.

9 is a characteristic graph according to a frequency variation method based on a general Kostas code. Referring to FIG. 9, when a frequency variation method based on the Kostas code is applied, the pattern of the HRR profile is blurred even in the presence of a velocity error, and the position of the scattering point is not changed. Therefore, It is advantageous to know.

In particular, an embodiment of the present invention can be applied to a very high frequency radar system.

On the one hand, those skilled in the art will recognize that the various illustrative logical blocks, components, and algorithms described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. In order to clearly illustrate this interchangeability of hardware and software, various exemplary blocks have been generally described above in terms of their functionality.

Whether such functionality is implemented as hardware or software depends upon the design constraints and specific applications imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the exemplary embodiments of the present invention.

The various illustrative logical blocks described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) Discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.

A general purpose processor may be a microprocessor, but, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

20: Target
200: Hybrid MPRF (Medium Pulse Repetition Frequency) signal processing device
210: Radar antenna
220:
230: Signal processor
240: All time

Claims (5)

A hybrid MPRF signal processing method using a frequency variable and a fixed method,
(a) acquiring a first received signal through a frequency fixing scheme for a radar signal received using a radar antenna;
(b) generating a distance-Doppler map using the first received signal;
(c) detecting and recognizing target and non-target information in the distance-Doppler map;
(d) obtaining a second received signal for the radar signal via a frequency varying scheme; And
(e) correcting the recognized target information in the second received signal to generate high resolution distance information for the target,
The frequency fixing method uses a fixed center frequency and the frequency variable method changes a center frequency step interval to be unequal, and the frequency variable method and the frequency fixing method are alternately used A hybrid MPRF signal processing method using frequency variable and fixed method.
The method according to claim 1,
Wherein the step (e) further comprises performing velocity correction on the high resolution distance information. ≪ Desc / Clms Page number 19 >
delete The method according to claim 1,
Further comprising the step of extracting angle information from the high resolution distance information after step (e). ≪ Desc / Clms Page number 19 >
In a hybrid MPRF signal processing apparatus using a frequency variable and fixed system,
Radar antenna;
A receiving unit for generating a radar signal from the radar antenna; And
Acquiring a first received signal through a frequency locking scheme for the radar signal, generating a distance-Doppler map using the first received signal, detecting target and non-target information in the distance-Doppler map, And a signal processing unit for acquiring a second received signal with respect to the radar signal through a frequency variable method and correcting the recognized target information in the second received signal to generate high resolution distance information on the target,
The frequency fixing method uses a fixed center frequency and the frequency variable method changes a center frequency step interval to be unequal, and the frequency variable method and the frequency fixing method are alternately used Hybrid MPRF signal processing device using frequency variable and fixed method.

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