KR100936173B1 - Filter bank and method for extracting Doppler frequency from target tracking device - Google Patents

Abstract

The present invention provides a filterbank and a method for extracting a Doppler frequency used to measure the moving speed of a target of interest in a target tracking device. The filter bank according to the present invention uses a matched filter for receiving a reflected signal and matching the frequency of the received signal when the signal transmitted to the target is reflected to measure the moving speed, and a signal output from the matched filter. And at least one range gate for measuring a distance to the target, and a narrowband filter for receiving a signal output from the range gate and filtering the received signal for each frequency band to output a Doppler frequency of the target.

Doppler, Filterbank, Tracking, Target of Interest, Frequency, Logic, Modulation

Description

FILTER BANK FOR EXTRACTING DOPPLER FREQUENCY IN TARGET DETECTOR AND METHOD THEREFOR}

The present invention relates to a filterbank and a method for extracting a Doppler frequency used to measure the moving speed of a target of interest in a target tracking device.

In general, a radar apparatus transmits a radio wave to an object for a predetermined time, calculates a time between transmission and reception by receiving a radio wave reflected from the object, detects a relative distance to the object, and detects the relative speed from the frequency component of the received signal. It is calculated and detected.

Velocity measurement of a moving target uses a Doppler signal to detect and process the Doppler signal to obtain information related to the speed of movement of the target. The implementation of the filter used in the actual processing process takes a parallel structure in which the narrow-band filter bank is allocated to each processor. The more precise the measuring device, the higher the sample frequency required for calculation, and the larger the amount of data.

Typically, the Doppler frequency detection is achieved by extracting multiple samples of the target of interest. In this case, taking multiple samples and calculating them requires time arrangement rather than performing one time. In addition, when the influence on the interference signal is not large, that is, when the interference influence on the operating frequency is not large from the outside, the technical operation for modulation and demodulation is relatively large. However, in the case of the system that needs to overcome the interference signal, the modulation / demodulation scheme for the operating frequency is added, which complicates the overall configuration or interface.

Currently used Doppler processing uses a combination of the above-mentioned method of obtaining multiple samples and a spectral comparison method for a single beam. The spectral comparison method for a single beam is based on the convolution operation of two signals. The calculation results are the same as those performed on the time axis and those performed on the frequency. However, in the convolution operation with 50 or more points, it is usually faster to perform the frequency comparison than the time axis.

On the other hand, when configuring the filter bank, if the amount of data and the number of filter channels to be processed within a required time increase, the complexity of the physical memory and processor that need to temporarily store the input RAW data is increased. At this time, the RAW data refers to data temporarily generated during the data processing.

In addition, a high-speed digital signal processor (DSP) and PPC are used for software processing. Since one processor performs Doppler filtering on a single channel at the same time, there is a restriction on the demand time. Software processing is relatively weak.

When a filter bank using a high-speed DSP is configured by using a spectral comparison method on a frequency, the number of DSPs is required according to the number of channels of the filter bank when the simultaneous processing compared to the total operating time is required, which complicates the overall configuration. In addition, increasing the hardware size of the system is inevitable.

Therefore, there is a need for a method of implementing a configuration of a filter bank for extracting Doppler frequencies for a target of interest with efficient concurrent logic to solve the above problems and to efficiently perform the processing and processing.

It is an object of the present invention to provide a filter bank for extracting Doppler frequencies used to measure the speed of movement of a target of interest in a target tracking device.

The filter bank extracting the Doppler frequency in the target tracking device according to an embodiment of the present invention receives the reflected signal when the signal transmitted to the target is reflected to measure the moving speed, and receives the reflected signal. Receives a signal output from the range gate, and a matching filter for matching a frequency, at least one range gate measuring a distance to the target using a signal output from the matching filter, and receiving the signal And a narrowband filter for filtering a signal by frequency band and outputting a Doppler frequency of the target.

According to another embodiment of the present invention, a method of extracting a Doppler frequency in a target tracking device includes receiving the reflected signal and receiving the reflected signal when the signal transmitted to the target to measure the moving speed is reflected. Performing a / D transform, generating downsampling data on the A / D converted signal, performing a fast Fourier transform (FFT) on the downsampling data, and performing the fast Fourier operation When the output data is generated, activating a counter connected to a filter bank for generating a synchro signal and extracting each Doppler frequency, and when the counter is activated, operating at least one memory, Generating corresponding addresses sequentially, providing the generated addresses to the memories, and the fast Fourier Complex multiplying the output data according to the arithmetic operation, the replica data stored in the memories for each index, and an inverse fast Fourier operation (IFFF) on the multiply output data. Transform) and output it.

According to the present invention there is provided a filterbank and a method for extracting a Doppler frequency used to measure the speed of movement of a target of interest in a target tracking device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are denoted by the same reference numerals wherever possible. In the following description and the annexed drawings, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a view showing a schematic configuration of a filter bank for extracting the Doppler frequency in the target tracking device according to an embodiment of the present invention.

The target tracking device transmits a radio wave to a moving target, and when the transmitted radio wave is reflected from the target, the target tracking device measures the moving speed of the target. When the signal reflected from the target moving to the target tracking device is received, the A / D converter 10 A / D converts the received signal. The converted signal is matched frequency in the matched filter (Matched Filter) 20 is determined.

The range gate 30 receives a signal whose frequency is determined by the matched filter 20. The range gate 30 is divided into different ranges according to the distance between the target and the target tracking device. The target tracking device calculates the distance between the target and the tracking device using the range gate 30. In addition, the target tracking device reflects from the target depending on the range of frequencies that the narrow bandpass filter 40 to which the signal is output is among the narrow bandpass filters 40 connected to each range gate 30. The frequency of the signal can be estimated.

The M Rage Gates 30 each include N narrowband filters 40 to once again filter the received data into signals for each frequency. The frequency passing through each narrowband filter 40 passes only a signal of a frequency corresponding to each narrowband filter 40, that is, each channel of CH 1 to CH N. At this time, M and N are arbitrary natural numbers.

2 is a graph showing a signal passing through the Doppler filter bank in the target tracking device according to an embodiment of the present invention.

Signals passing through the Doppler filter bank can be classified by section according to each filter as shown in FIG. In FIG. 2, signals of frequency sections according to ( ^2M −1) filters are shown. The signal passing through the Doppler filter bank of FIG. 1 is divided into signals having a narrow bandwidth bandwidth for each frequency.

3 is a graph showing peak values detected according to the number of sampling in the target tracking device according to an exemplary embodiment of the present invention.

The detection of the Doppler frequency for several samples can be obtained using the peak value. When the peak value detected as shown in FIG. 3 is subjected to a fast Fourier transform (FFT) by the number of final sample points, the final Doppler frequency can be extracted as shown in FIG. 4 below. The peak value detected in FIG. 3 is extracted by a fast Fourier operation of the maximum peak value according to the number of samples.

FIG. 4 is a graph illustrating a Doppler signal detected by fast Fourier calculation of a detected peak value in a target tracking device according to an exemplary embodiment of the present invention. Referring to FIG. ⁴ , it can be seen that the Doppler frequency of the input data is 1 × 10 ⁴ .

5 is a block diagram illustrating a schematic configuration of a digital signal processor through a convolution operation on a frequency axis in a target tracking device according to an embodiment of the present invention.

The operations performed in the digital signal processor are as follows. The A / D converter 110 receives the signal reflected from the target and performs A / D conversion, and the direct digital converter (DDC) logic 120 receives the A / D converted signal and down-sampling data. Create Sampling of data is handled by the FFT logic 130. In addition, the FFT logic 130 configures floating point arithmetic and timing delay logic at the input and output stages to achieve overall synchronization. When the counter (not shown) is activated, addresses are sequentially generated and provided to the memory 140 while operating each memory 140.

The digital signal processor according to the present embodiment performs simultaneous processing but does not use memory for each channel if the number of channels and the calculation time of the filter bank allow. The memory 140 stores a shifted replica component for each Doppler channel. In the process of data processing, if a memory is not used for each channel but is used as one memory, a predetermined delay operation according to a channel is performed as shown in FIG. 8 using spectral components of only one memory and a reference frequency. In this case, the transition section for each channel may be sequentially processed by adding 0 bits.

The operation result calculated by the FFT logic 130 and the duplicated data output from the memory 140 are input to the multiplier logic 160 for each index, and the multiplier 160 performs a multiplication operation on the two data. Perform. The data output from the multiplier 160 is output to the inverse fast fourier transform (IFFF) logic 160, and the IFFF logic performs an inverse fast Fourier operation using the data output from the multiplier 160.

In the case of signal detection for a single pulse, the signal can be detected through spectral comparison with respect to the modulated signal. As shown in Equation 1 below, a spectrum comparison method for a received signal determines a matching degree of a transmitted / received signal through a convolution operation on a time axis to obtain a filter output. It is preferable to perform a convolution operation over a predetermined point on the frequency axis rather than the time axis.

The spectral comparison method is a result of transitioning to the left or right from the center as a starting point when the Doppler is generated based on the modulation spectrum on the zero Doppler as shown in FIG. 6 below. Therefore, when the final matched filter is passed through the model applied in FIG.

The Control & Monitoring Logic 170 controls the overall operation of the target tracker.

6 is a diagram illustrating a signal according to Doppler frequency shift in the target tracking device according to an embodiment of the present invention. Referring to Figure 6 it can be seen that the frequency shift due to the Doppler phenomenon. It can be seen that the signal located in the center in (a) moved to Delta f in (b).

FIG. 7 is a diagram illustrating data output from a matched filter in a target tracking device according to an exemplary embodiment of the present invention. Referring to FIG. 7, a frequency matching the signal received from the target tracking device may be known.

8 is a block diagram illustrating a schematic configuration of a digital signal processor through a convolution operation on a frequency axis to which delay logic is added in FIG. 5 according to an embodiment of the present invention. Referring to FIG. 8, it can be seen that two delay logics having coefficients of '-1' have been added to add multipliers of # 2 and # 3.

9 is a view showing the output of the filter finally implemented in the target tracking device according to an embodiment of the present invention.

In FIG. 9, the # 1 channel filter output, the # 2 channel filter output, the # 3 channel filter output, the # 4 channel filter output, and the # 5 channel filter output are shown in sequence. The target tracking device of FIG. 9 has an IF Doppler signal of 50.4 MHz. The range of each filter shown in FIG. 9 is 0KHz, 160KHz, 320KHz, 480KHz, 640KHz, and the Doppler frequency is 400KHz, and the Doppler frequency is shown in the # 3 channel.

FIG. 10 illustrates an implementation logic of a filter bank for extracting Doppler frequencies in a target tracking device according to an exemplary embodiment of the present invention. FIG. 11 is a block diagram showing a schematic configuration of logic for generating an external test signal received by a target tracking device according to an embodiment of the present invention, and FIG. 12 is a block diagram showing a schematic configuration of DDC logic. FIG. 13 is a block diagram illustrating a schematic configuration of FFT logic for performing an FFT operation. FIG. 14 is a block diagram showing an approximate configuration of memory logic for generating a synchronization signal in the target tracking device, and FIG. 15 is a block diagram showing an approximate configuration of a multiplier and an IFFT filter output logic in the target tracking device. It is also. In order to implement the target tracking device according to the present invention, logics as shown in FIGS. 10 to 15 may be used.

1 is a view showing a schematic configuration of a filter bank for extracting the Doppler frequency in the target tracking device according to an embodiment of the present invention.

2 is a graph showing a signal passing through the Doppler filter bank in the target tracking device according to an embodiment of the present invention.

3 is a graph showing peak values detected according to the number of sampling in the target tracking device according to an exemplary embodiment of the present invention.

4 is a graph illustrating a Doppler signal detected by FFT calculation of a detected peak value in a target tracking device according to an exemplary embodiment of the present invention.

5 is a block diagram illustrating a schematic configuration of a digital signal processor through a convolution operation on a frequency axis in a target tracking device according to an embodiment of the present invention.

6 is a diagram illustrating a signal according to Doppler frequency shift in the target tracking device according to an embodiment of the present invention.

7 is a view showing a signal output from the matched filter in the target tracking device according to an embodiment of the present invention.

8 is a block diagram illustrating a schematic configuration of a digital signal processor through a convolution operation on a frequency axis to which delay logic is added in FIG. 5 according to an embodiment of the present invention.

9 is a view showing the output of the filter finally implemented in the target tracking device according to an embodiment of the present invention.

FIG. 10 illustrates an implementation logic of a filter bank for extracting Doppler frequencies in a target tracking device according to an exemplary embodiment of the present invention.

11 is a block diagram illustrating a schematic configuration of logic for generating an external test signal received by a target tracking device according to an exemplary embodiment of the present invention.

12 is a block diagram illustrating a schematic configuration of DDC logic in a target tracking device according to an embodiment of the present invention.

FIG. 13 is a block diagram illustrating a schematic configuration of an FFT logic for performing fast Fourier operations in the target tracking device according to an embodiment of the present invention.

14 is a block diagram illustrating a schematic configuration of a memory logic for generating a synchronization signal in a target tracking device.

FIG. 15 is a block diagram showing a schematic configuration of a multiplier and an IFFT filter output logic in a target tracking device.

Claims (3)

In the filter bank to extract the Doppler frequency in the target tracking device, A matched filter for receiving the reflected signal and matching the frequency of the received signal when the signal transmitted to the target is reflected to measure the moving speed; At least one range gate measuring a distance to the target using a signal output from the matched filter; A narrowband filter for receiving a signal output from the range gate and filtering the received signal for each frequency band to output a Doppler frequency of the target, The range gate is The filter bank for extracting the Doppler frequency in the target tracking device, characterized in that for distinguishing the distance from the target by at least one range, and receiving a signal output from the matching filter according to the separated range. delete In the method of extracting the Doppler frequency in the target tracking device, When the signal transmitted to the target is reflected to measure the moving speed, receiving the reflected signal and performing A / D conversion on the received signal; Generating downsampling data for the A / D converted signal; Performing a fast Fourier transform (FFT) on the downsampling data; Activating a counter connected to a filter bank for extracting each Doppler frequency by generating a synchronization signal when the output data according to the fast Fourier operation is generated; When the counter is activated, operating at least one memory, sequentially generating addresses corresponding to the memories, and providing the generated addresses to the memories; Complex multiplying the output data according to the fast Fourier operation and the replica data previously stored in the memories for each index; And performing an inverse fast fourier transform (IFFF) on the multiplied and output data to output the Doppler frequency in the target tracking device.

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