JP2014173943A - Rader system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rader system capable of minimizing erroneous deletion of a movement target by a blind speed and accurately detecting the speed of target in an MTI processing.SOLUTION: The rader system includes: an antenna unit for transmitting and receiving signals; a transmitting/receiving unit for generating a transmission signal having multiple pulses with different time intervals between pulses in a CPI to transmit it to the antenna unit and performing reception processing of a received signal input from the antenna unit; and a signal processor for processing MTI processing for the received signal and calculating a frequency and an amplitude of the received signal for each pulse pattern by selecting pulses whose pulse patterns structuring a stagger unit are the same.

Description

  Embodiments described herein relate generally to a radar apparatus.

  Some radar devices perform MTI (moving target indicator) processing and pulse Doppler processing. Here, the MTI process is a process of removing a fixed component having no speed by taking a difference between signals received with a certain time interval and extracting a speed component. In MTI, when the amount of phase rotation of the reflected wave is an integral multiple of 2π, the speed component may not be detected even though the target is moving. This is called blind speed. In a conventional radar apparatus, staggering is performed to change the repetition cycle between pulses in order to reduce erroneous erasure of a target due to this blind speed.

  Further, a radar apparatus that performs pulse Doppler processing extracts a Doppler component of a moving target using a plurality of pulses. The interval between the repeated patterns of the predetermined number of pulses is referred to as CPI (Coherent Processing Interval).

  A radar that performs pulse Doppler processing can also perform MTI, but the pulse repetition period in the CPI is usually fixed in consideration of the processing load of pulse Doppler, and an inter-pulse stagger that changes the repetition period between pulses is performed. In this CPI, the target cannot be detected when the target moving speed matches the blind speed. In such a radar apparatus, as a countermeasure against the blind speed, a group stagger for changing the pulse repetition frequency in the next CPI and an inter-scan stagger for changing the pulse repetition frequency in the next scan have been performed.

  However, in a radar apparatus that deals with a high-speed moving target or a radar apparatus with few target detection opportunities, there is a problem in that tracking accuracy is lowered because a 1 CPI target cannot be detected.

JP 2009-63507 A

  Accordingly, there is a need for a radar apparatus that can detect a target speed with high accuracy while minimizing erroneous deletion of a moving target due to blind speed in MTI processing.

  In order to solve the above problem, an embodiment of the present invention generates an antenna device that transmits and receives signals and a transmission signal having a plurality of pulses having different time intervals between pulses in the CPI. Transmitting / receiving device that performs reception processing of received signal input from antenna device, and MTI processing on received signal, and selects the same repetition frequency within the pulses that constitute CPI, and the frequency of the received signal And a signal processing device for calculating the amplitude.

It is a block diagram which shows the structure of a radar apparatus. It is a figure which shows the example of the stagger unit in this embodiment. It is a figure which shows a pulse pattern. It is a figure which shows the example of the result of FFT performed by the signal processing apparatus. It is a figure which shows the integration process which the signal processing apparatus performed. It is a figure which shows operation | movement of a signal processing apparatus.

  Hereinafter, an embodiment of a radar apparatus will be described in detail with reference to the drawings.

  The radar apparatus according to the present embodiment generates a transmission signal having a plurality of pulses having different time intervals between pulses in the CPI and transmits / receives the signal to / from the antenna apparatus, and receives the input from the antenna apparatus. A transmission / reception device that performs signal reception processing, and a signal processing device that performs MTI processing on the reception signal, selects signals having the same repetition period in the pulses constituting the CPI, and calculates the frequency and amplitude of the reception signal Prepare.

  FIG. 1 is a block diagram illustrating a configuration of a radar apparatus according to the present embodiment. As shown in FIG. 1, the radar apparatus according to the present embodiment performs an antenna device 10 that transmits and receives signals, and generates a transmission signal, transmits the signal to the antenna device 10, and performs reception processing of a reception signal input from the antenna device 10. A transmission / reception device 20 that performs the signal processing, and a signal processing device 30 that performs signal processing of the received signal.

  The antenna apparatus 10 can use, for example, a reflector system using a reflector or an array antenna system in which a plurality of antenna elements are arranged in an array and the transmission signal transmission direction is changed by changing the phase of the transmission signal. .

  The transmission / reception device 20 generates and receives a transmission signal having a plurality of pulses having different time intervals between pulses in the CPI.

  Here, the radar apparatus of the present embodiment performs a moving target indicator (MTI) process and a pulse Doppler process. The MTI process is a process for removing a fixed component having no speed and extracting a speed component by taking a difference between signals received at a certain time interval.

  This radar apparatus transmits a predetermined number of pulses for performing pulse Doppler processing. This predetermined pulse period is referred to as CPI (Coherent Processing Interval).

  The signal processing device 30 includes a CPU 31 that is an arithmetic device, a RAM 32 that is a storage device, and a ROM 33.

  The signal processing device 30 performs MTI processing on the received signal, selects those having the same repetition period in the pulse patterns constituting the CPI, and receives the frequency of the received signal for each pulse pattern by, for example, FFT (Fast Fourier Transform). And the amplitude is calculated, and the target velocity is detected by integrating the amplitude for each frequency with respect to the calculated frequency and amplitude for each pulse pattern.

  FIG. 2 is a diagram illustrating an example of an inter-pulse stagger in the CPI in the present embodiment. As shown in FIG. 2, the transmission / reception device 20 generates a transmission signal with different pulse intervals in the CPI.

  FIG. 2 shows a case where the number of staggered pulses is three. The time interval between the first pulse and the next second pulse is A, the time interval between the second pulse and the next third pulse is B, the time interval between the third pulse and the following pulse is C, Thereafter, A, B, and C are repeated. The unit of the repetition period of A, B, and C is called a stagger unit.

  By making the time interval A, the time interval B, and the time interval C different from each other, it is possible to minimize the coincidence between the target moving speed and the blind speed.

  The order of the time intervals of the pulses constituting the stagger unit is equal to the order of the time intervals of the pulses constituting the subsequent stagger unit. That is, when a pulse is generated by the time interval A, the time interval B, and the time interval C in the stagger unit, a pulse is also generated by the time interval A, the time interval B, and the time interval C in the subsequent stagger unit.

  FIG. 3 is a diagram showing a pulse pattern. As shown in FIG. 3, when the number of pulses in the stagger unit is n (n is an integer), n consecutive pulses are selected, and n pulse patterns are defined.

  Specifically, when the number of pulses in the stagger unit is 3, the pulse pattern includes three patterns of ABC (hereinafter referred to as X), BCA (hereinafter referred to as Y), and CAB (hereinafter referred to as Z). It is. When n + 1 stagger units are included in the CPI, n pulse patterns can be defined.

  Each pulse pattern, in this example X, Y, and Z time intervals and their sum, are equal.

  The signal processing device 30 performs FFT on the received signal for each pulse pattern. That is, with respect to X, FFT is performed using the first X (X1) to nth X, and n is similarly used for Y and Z.

  FIG. 4 is a diagram illustrating an example of the result of the FFT performed by the signal processing device 30. As shown in FIG. 4, the signal processing device 30 calculates the amplitude for each frequency for each pulse pattern X, Y, Z for the received signal.

  FIG. 5 is a diagram illustrating the integration process performed by the signal processing device 30. As shown in FIG. 5, the signal processing device 30 determines the target moving speed by integrating the amplitude for each frequency with respect to the FFT result of each pulse pattern.

  FIG. 6 is a diagram illustrating the operation of the signal processing device 30. As shown in FIG. 6, in step 601, the signal processing device 30 inputs a reception signal from the transmission / reception device 20.

  In step 602, the signal processing device 30 stores the received signal in the RAM 32 for each pulse.

  In step 603, the signal processing apparatus 30 determines whether or not reception signals for CPI have been stored. The signal processing device 30 proceeds to step 604 when it is determined that the received signals for CPI have been stored, and returns to step 601 when it is determined that it has not been stored.

  In step 604, the signal processing apparatus 30 repeats the processing up to step 608 n times. That is, the signal processing apparatus 30 performs MTI processing for X1 in step 605, performs MTI processing for Y1 in step 606, and performs MTI processing for Z1 in step 607. These processes are performed up to Xn, Yn, and Zn.

  In step 609, the signal processing apparatus 30 calculates the amplitude for each frequency by FFT using X1 to Xn for X after MTI processing.

  In step 610, the signal processing apparatus 30 calculates the amplitude for each frequency by FFT using Y1 to Yn for Y after MTI processing.

  In step 611, the signal processing apparatus 30 calculates the amplitude for each frequency by FFT using Z1 to Zn for Z after MTI processing.

  In step 612, the signal processing device 30 integrates the amplitude calculated for each pulse pattern for each frequency. That is, the signal processing device 30 integrates the FFT result for X, the FFT result for Y, and the FFT result for Z.

  In step 613, the signal processing device 30 detects the target moving speed from the integration result.

  As described above, the radar apparatus according to the present embodiment generates an antenna apparatus 10 that transmits and receives signals, and a transmission signal having a plurality of pulses having different time intervals between pulses in the CPI, and transmits the transmission signal to the antenna apparatus 10. The transmission / reception device 20 that performs reception processing of the reception signal input from the antenna device 10 and the MTI processing on the reception signal are performed, and those having the same pulse pattern constituting the CPI are selected to receive signals for each pulse pattern. And a signal processing device 30 that detects the target speed by integrating the amplitude for each frequency with respect to the calculated frequency and amplitude for each pulse pattern.

  Therefore, since staggering is performed in the CPI, it is possible to minimize the erroneous erasure of the moving target due to the blind speed in the MTI process and to detect the target speed with high accuracy.

  Although several embodiments have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

10: Antenna device 20: Transmission / reception device 30: Signal processing device

Claims (5)

An antenna device for transmitting and receiving signals;
A transmission / reception device that generates a transmission signal having a plurality of pulses with different time intervals between pulses in the CPI, sends the transmission signal to the antenna device, and performs reception processing of the reception signal input from the antenna device;
A signal processing device that performs MTI processing on the received signal, selects the same pulse pattern constituting the CPI, and calculates the frequency and amplitude of the received signal for each pulse pattern;
A radar apparatus comprising: The signal processing device includes:
The radar apparatus according to claim 1, wherein the target velocity is detected by integrating the amplitude for each frequency with respect to the calculated frequency and amplitude for each pulse pattern.   The radar apparatus according to claim 2, wherein a sum of time intervals between pulses constituting the pulse pattern is equal in each pulse pattern.   The radar apparatus according to claim 3, wherein the order of the time intervals of the pulses constituting the stagger unit is equal to the order of the time intervals of the pulses constituting the subsequent stagger unit. The pulse pattern is
5. The radar apparatus according to claim 4, wherein when the number of pulses in the stagger unit is n (n is an integer), n consecutive pulses are selected and n pulse patterns are defined.

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