JP2010185768A - Weather information detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weather information detection apparatus which can correctly extract only a weather component by removing a fluctuating component of a ground clutter signal without falsely detecting it as a weather signal and a weather information detection method using the apparatus. <P>SOLUTION: A weather Doppler pass filter circuit which selectively passes a weather component included in a radar reception signal is provided at the front stage of a weather information detection circuit. The weather Doppler pass filter circuit includes a bandpass filer which passes a frequency bandwidth related to the weather component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a meteorological information detection apparatus and a meteorological information detection method using the apparatus, and more particularly to a meteorological information detection apparatus using a received signal of a Doppler radar apparatus and a meteorological information detection method using the apparatus. Related.

  The following methods are known for detecting weather information. As one method, there is a method of obtaining a differential signal from a received signal output from a Doppler radar device with a ground clutter (ground clutter) component. As another method, there is a method of detecting weather information by removing a ground clutter component from an I / Q detection signal output from a radar device using a canceller circuit. Each of these two weather information detection methods will be described using an example of a weather information detection device.

  FIG. 1 is a block diagram for explaining a configuration example of a weather detection apparatus according to a technique related to the present invention. The weather detection circuit includes a memory write / read control unit 11, a buffer memory 12, a memory read control unit 13, a ground clutter memory 14, a difference circuit unit 15, and a weather information detection circuit unit 16.

  The output unit of the memory write / read control unit 11 is connected to the first input unit of the buffer memory 12. The output unit of the buffer memory 12 is connected to the first input unit of the difference circuit unit 15. The output unit of the memory read control unit 13 is connected to the input unit of the ground clutter memory 14. The output unit of the ground clutter memory 14 is connected to the second input unit of the difference circuit unit 15. The output unit of the difference circuit unit 15 is connected to the input unit of the weather information detection circuit unit 16.

  The memory write / read controller 11 receives a trigger signal, a clock signal, and an orientation signal, and outputs a memory write signal and a memory read signal. The buffer memory 12 receives a radar reception signal from the second input unit, and receives a memory write signal and a memory read signal from the first input unit. The buffer memory 12 holds or outputs the radar reception signal according to the memory write signal or the memory read signal. The memory read control unit 13 inputs a trigger signal, a clock signal, and an azimuth signal, and outputs a memory read signal. The ground clutter memory 14 receives a memory read signal and outputs ground clutter data. The difference circuit unit 15 receives the radar reception signal from the buffer memory from the first input unit, receives the ground clutter data from the second input unit, and outputs the difference data. The weather information detection circuit unit 16 inputs the difference data and outputs the weather detection data.

  The operation of the weather detection circuit in the example of FIG. 1 will be described. First, a raw signal that is received by the radar device and is not subjected to MTI (Moving Target Indication) processing is obtained. This raw radar reception signal is stored in one buffer memory 12 as it is. The other ground clutter memory 14 extracts and stores the ground clutter signal from the raw radar received signal. Next, the difference between the stored raw signal and the stored ground clutter signal is taken as a difference signal. Finally, weather information is detected from the difference signal.

  FIG. 2 is a block diagram for explaining a configuration example of a weather information detection apparatus according to another technique related to the present invention. The meteorological information detection apparatus includes an IQ (In-Phase and Quadrature-Phase) synthesis circuit unit 21, a canceller circuit unit 22, and a meteorological information detection circuit unit 23. The IQ synthesis circuit unit 21, the canceller circuit unit 22, and the weather information detection circuit unit 23 are connected in series in this order.

  The IQ synthesis circuit unit 21 inputs an I signal and a Q signal of radar detection, a trigger signal, and a clock signal, and outputs an IQ synthesis signal. The canceller circuit 22 receives the IQ composite signal, cancels a part of the component, and outputs it. The weather information detection circuit unit 23 receives the output signal of the canceller circuit unit 22 and outputs weather detection data.

  In the example of FIG. 2, a canceller circuit 22 for performing MTI processing on a radar reception signal received by the radar device is used. The ground clutter component is removed by the canceller circuit 22 from the I / Q detection signal output from the radar device.

  In the weather information detection apparatus according to the related art shown in FIG. 1 or FIG. 2, it is assumed that the characteristics of the ground clutter component are always constant and the Doppler frequency is zero. Of the received signal of the radar, the ground clutter component is a component reflected from the stationary target.

  In particular, in the meteorological information detection apparatus according to the related technology of FIG. 2, as a result, the phase of the I / Q detection signal is also fixed. In this case, it is well known that the ground clutter component in the received signal of the radar can be suppressed by using the canceller circuit 22.

  However, in practice, a stationary target that produces a ground clutter component is not completely stationary. For example, mountains that occupy most of the ground clutter component are stationary targets, but the trees that grow on the surface fluctuate with the wind. In other words, in the I / Q detection signal, the component reflected by the mountain or the like in the radar reception signal includes the characteristics of the dynamic signal, as the component reflected by the aircraft or the like. As a result, a phase fluctuation is generated in the I / Q detection signal although it is minute.

  In this case, the canceller circuit 22 cannot completely remove the ground clutter component. In particular, the amount of fluctuation of the Doppler frequency varies depending on the surrounding weather conditions such as wind direction, wind speed, airflow, etc., due to fluctuations in the trees. As a result, the phase fluctuation of the ground clutter component included in the I / Q detection signal may become so large that it cannot be removed by the canceller circuit. In such a case, naturally, the ground clutter component passes through the canceller circuit.

  Also, a similar problem may occur in the weather information detection apparatus according to the related technology of FIG. For example, even if signals received from the same mountain store the ground clutter component at a certain time, the ground clutter components at another time do not always match. That is, for example, due to fluctuations caused by fluctuations in mountains, a difference occurs between the previously stored ground clutter component and the currently received ground clutter component.

  Furthermore, since the fluctuation characteristics of the ground clutter component are not constant, the ground clutter component may remain in the differential signal. As a result, when detecting weather information, a phenomenon may occur in which a ground clutter component is erroneously detected as a rain cloud or the like.

In relation to the above, Patent Document 1 (Japanese Utility Model Laid-Open No. 05-023173) discloses a description related to a signal processing device in a weather radar.
A signal processing apparatus for a weather radar described in Patent Document 1 includes an AD conversion unit for a received signal, a short-distance MTI unit, a long-distance MTI unit, and a switching unit for each short-distance and long-distance MTI unit. Prepare.

Patent Document 2 (Japanese Patent Laid-Open No. 08-166445) discloses a description relating to a radar apparatus.
The radar apparatus described in Patent Document 2 radiates radio waves from an antenna, receives reflected radio waves from a target with respect to the radiated radio waves, and measures the distance and direction between the target and the antenna. This radar apparatus includes a receiver, a Doppler filter, and bird flock determination means. Here, the receiver converts the reflected radio wave received by the antenna into a reflected signal as an electric signal. The Doppler filter extracts a Doppler frequency component from the reflected signal. The bird group determination means extracts a Doppler frequency component having a certain bandwidth or more from the extracted Doppler frequency components, and determines this as a bird group.

Japanese Utility Model Publication No. 05-023173 Japanese Patent Laid-Open No. 08-166445

  Even in a fixed object such as a mountain, the ground clutter signal may fluctuate, and this fluctuation may be erroneously detected as a weather component. From the viewpoint of the Doppler characteristic of radar signal processing, the fluctuation component of the ground clutter signal is extremely small compared to a dynamic target object such as a rain cloud that is to be detected as the original weather component. That is, the fluctuation of the ground clutter signal is in the vicinity of 0 (zero) Doppler and can be distinguished from a dynamic signal such as rain clouds.

  An object of the present invention is to remove a fluctuation component of a ground clutter signal without erroneously detecting it as a weather signal, and to correctly extract only the weather component, and a meteorological information detection method using this device, Is to provide.

  A weather information detection apparatus according to the present invention includes a weather Doppler pass filter circuit and a weather information detection circuit. Here, the weather Doppler pass filter circuit inputs a radar reception signal and selectively passes a signal component corresponding to weather information. The weather information detection circuit generates weather detection data based on the output signal of the weather Doppler pass filter circuit. The weather Doppler pass filter circuit includes a band pass filter that selectively passes a frequency band corresponding to weather information.

  The meteorological information detection method according to the present invention is based on (a) a step of inputting a radar reception signal and selectively passing a signal component corresponding to meteorological information; and (b) an output signal obtained in step (a). Generating weather detection data. Here, step (a) includes (a-1) a step of selectively passing through a frequency band corresponding to weather information.

  According to the meteorological information detection apparatus and the meteorological information detection method using the apparatus according to the present invention, even if a fluctuation component is included in the ground clutter, the fluctuation component is removed without being mistaken as a weather signal. It becomes possible to improve the extraction of weather components.

FIG. 1 is a block diagram for explaining a configuration example of a meteorological information detection apparatus according to a technique related to the present invention. FIG. 2 is a block diagram for explaining a configuration example of a weather information detection apparatus according to another technique related to the present invention. FIG. 3 is a block diagram for schematically explaining the configuration of the weather information detecting apparatus according to the first embodiment of the present invention. FIG. 4 is a radar waveform diagram for explaining a signal received and output by an existing radar device. FIG. 4A is a polar graph showing a radar reception signal. FIG. 4B is a graph showing a radar reception signal as a distribution of signal intensity as a function of Doppler frequency. FIG. 5 is a graph for explaining the characteristics of the weather Doppler pass filter circuit. FIG. 5A is a polar graph showing a radar reception signal. FIG. 5B is a graph representing the radar received signal as a distribution of signal strength as a function of Doppler frequency. FIG. 6 is a graph for comparing an input signal and an output signal in a weather Doppler pass filter circuit according to the present invention. FIG. 6A is a frequency distribution diagram of signals input by the weather Doppler pass filter circuit. FIG. 6B is a frequency distribution diagram of a signal output from the weather Doppler pass filter circuit. FIG. 7 is a block diagram for explaining a detailed configuration of the weather information detection circuit according to the first embodiment of the present invention. FIG. 8 is a block diagram for explaining a configuration example of the weather information detecting apparatus according to the second embodiment of the present invention.

  With reference to the attached drawings, an embodiment for implementing a meteorological information detection apparatus according to the present invention and a meteorological information detection method using the apparatus will be described below.

(First embodiment)
FIG. 3 is a block diagram for schematically explaining a configuration example of the weather information detecting apparatus according to the first embodiment of the present invention. The weather information detection device includes a weather Doppler passage filter circuit 31 and a weather information detection circuit 32.

  The output unit of the weather Doppler pass filter circuit 31 is connected to the input unit of the weather information detection circuit 32. A radar receiver 50 (not shown) is connected to the preceding stage of the weather Doppler pass filter circuit 31.

  The weather Doppler pass filter circuit 31 receives a radar reception signal output from the radar receiver 50, a trigger signal, and a clock signal, and outputs a weather signal including weather information. The weather information detection circuit 32 inputs a weather signal and outputs weather information detection data. The clock signal is for synchronizing the operation of each component in the weather information detection apparatus. The trigger signal is for controlling the operation of each component in the weather information detection apparatus. In addition, the weather information detection apparatus according to the present invention may further use a direction signal in addition to the clock signal and the trigger signal. The direction signal is a signal for transmitting information relating to the direction of the observation target detected by the radar receiver.

  A reception signal output from the radar receiver 50 will be described.

  FIG. 4 is a radar waveform diagram for explaining a signal received and output by an existing radar device. FIG. 4A is a polar graph showing a radar reception signal. In this polar graph, the center point indicates the position of the radar device, and the length in the radial direction indicates the distance from the radar device to the moving target. FIG. 4B is a graph showing a radar reception signal as a distribution of signal intensity as a function of Doppler frequency. In this graph, the horizontal axis indicates the Doppler frequency, and the vertical axis indicates the signal intensity. In either case, the moving target is color-coded according to its Doppler frequency, but this is indicated by the difference in mesh (hatching) in the drawing.

  The ground clutter component is indicated by the first mesh. Of the radar received signal, the ground clutter component is a component reflected by the ground, sea surface, building, or the like. That is, since the ground clutter component corresponds to the static target object, the Doppler shift amount should be zero. However, in reality, the Doppler shift amount is wide due to the fluctuation of plants growing on the ground surface and the movement of waves standing on the sea surface.

  The weather clutter component is indicated by a second mesh. Of the radar reception signal, the weather clutter component is a component reflected by a rain cloud or the like. A target object related to weather, such as a rain cloud, is a dynamic target object that moves slowly but momentarily. Since the dynamic target object related to the weather moves faster than the static target object, the Doppler shift amount is larger than the ground clutter component.

  A third mesh indicates a clutter component caused by an aircraft that can be said to be the original target of the radar receiver. That is, of the radar reception signal, the clutter component by the target is a component reflected by, for example, an aircraft. Actually, since the Doppler shift amount is narrow, it appears as a solid line. In the example of this figure, since the moving speed of the target aircraft is substantially constant, the Doppler shift amount is narrow.

  The operation of the weather Doppler pass filter circuit 31 will be described.

  FIG. 5 is a graph for explaining the characteristics of the weather Doppler pass filter circuit 31. FIG. 5A is a polar graph showing a radar reception signal, which is the same as FIG. 4A. FIG. 5B is a graph showing the radar reception signal as a distribution of signal intensity as a function of the Doppler frequency, and a graph showing the frequency characteristics of the weather Doppler pass filter circuit 31 is added to FIG. 4B. Equal to the thing.

  The weather Doppler pass filter circuit 31 includes a band pass filter that passes only the frequency band corresponding to the weather clutter among the radar reception signals obtained from the radar receiver 50. In other words, the weather Doppler pass filter circuit 31 includes a band-pass filter that excludes the Doppler frequency band corresponding to the ground clutter or the target clutter other than the weather clutter.

  FIG. 6 is a graph for comparing the input signal and the output signal in the weather Doppler pass filter circuit 31 according to the present invention. FIG. 6A is a frequency distribution diagram of a signal input by the weather Doppler pass filter circuit 31. FIG. 6B is a frequency distribution diagram of a signal output from the weather Doppler pass filter circuit 31. The weather signal output from the weather Doppler pass filter circuit 31 does not include a ground clutter component or a target clutter component. Therefore, the probability of erroneously detecting the ground clutter component as weather information becomes extremely small.

  The weather Doppler pass filter circuit 31 may further use a clock signal, an azimuth signal, a trigger signal, and the like output from the radar receiver 50 when performing the operation as a bandpass filter.

  FIG. 7 is a block diagram for explaining a detailed configuration of the weather information detection circuit according to the first embodiment of the present invention. This weather information detection circuit includes a radar receiver 50, an IQ synthesis circuit 52, an interference removal circuit 54, a weather Doppler passage filter circuit 56, and a weather information detection circuit 58.

  The radar receiver 50, the IQ synthesis circuit 52, the interference removal circuit 54, the weather Doppler filter circuit 56, and the weather information detection circuit 58 are connected in series in this order. The radar receiver 50 is further connected to an interference removal circuit 54, a weather Doppler pass filter circuit 56, and a weather information detection circuit 58.

  The radar receiver 50 outputs an I detection signal and a Q detection signal 51 as a radar reception signal, a clock signal 59, an orientation signal 60, and a trigger signal 61. The IQ synthesis circuit 52 inputs the I detection signal and the Q detection signal 51, the clock signal 59, the azimuth signal 60, and the trigger signal 61, and outputs the I / Q signal 53 of the radar reception signal. The interference cancellation circuit unit 54 receives the I / Q signal 53, the clock signal 59, the azimuth signal 60, and the trigger signal 61, and outputs the I / Q signal 55 after interference cancellation. The weather Doppler pass filter circuit 56 receives the I / Q signal 55 after interference cancellation, the clock signal 59, the azimuth signal 60, and the trigger signal 61, and outputs a weather signal 57. The weather information detection circuit unit 58 receives the weather signal 57, the clock signal 59, the direction signal 60, and the trigger signal 61, and outputs weather detection data.

  The operation of the IQ synthesis circuit 52 will be described. The IQ synthesis circuit 52 inputs the I detection signal and the Q detection signal output from the radar receiver 50. The IQ combining circuit 52 combines the I detection signal and the Q detection signal to generate an I / Q signal.

  The IQ synthesis circuit 52 may use a clock signal, a direction signal, a trigger signal, or the like output from the radar receiver 50 in order to synthesize the I detection signal and the Q detection signal.

  The IQ synthesizing circuit 52 may be the same as that according to a well-known technique, and a detailed description thereof will be omitted.

  The operation of the interference removal circuit 54 will be described. Usually, radar output signals are mixed with signals output from other radars and interfere with each other. Since the frequency band of the interference signal is unknown, there is a possibility that the interference signal will pass through a weather Doppler pass filter circuit 56 described later. Therefore, the interference removal circuit 54 removes interference signals from other radars.

  The interference removal circuit 54 may use a clock signal, a direction signal, a trigger signal, or the like output from the radar receiver 50 in order to recognize an interference signal from another radar.

  The interference removal circuit 54 may be the same as that of a well-known technique, and thus a further detailed description is omitted.

  The weather Doppler pass filter 56 is the same as the weather Doppler pass filter 31 described above, and a detailed description thereof will be omitted.

  The operation of the weather information detection circuit 58 will be described. The weather signal 57 input by the weather information detection circuit 58 includes only the Doppler frequency band corresponding to the weather clutter. Further, interference signals from radars other than the radar receiver 50 are also removed.

  Further, each of the circuits 52, 54, 56 connected between the radar receiver 50 and the weather information detection circuit 58 operates by inputting the clock signal, direction signal, and trigger signal of the radar receiver 50. Therefore, the weather information detection circuit 58 can also operate in synchronization with each of the clock signal, the direction signal, and the trigger signal.

(Second Embodiment)
FIG. 8 is a block diagram for explaining a configuration example of the weather information detecting apparatus according to the second embodiment of the present invention. The meteorological information detection apparatus according to the present embodiment includes the IQ synthesis circuit 52, the interference removal circuit 54, the weather Doppler pass filter circuit 56, and the weather information detection circuit 58 according to the first embodiment. Here, an external radar receiver can be connected to the preceding stage of the IQ combining circuit 52. In other words, the meteorological information detection apparatus according to the present embodiment removes only the radar receiver 50 from the meteorological information detection apparatus according to the first embodiment of the present invention, and each signal enables connection to an external radar receiver instead. It is equal to what added the input parts 81-85. These input units include an I detection signal input unit 81, a Q detection signal input unit 82, a clock signal input unit 83, an azimuth signal input unit 84, and a trigger signal input unit 85. Except for these differences, the meteorological information detection apparatus according to the present embodiment is the same as the meteorological information detection apparatus according to the first embodiment, and thus further detailed description is omitted.

  As an external radar receiving device, for example, an airport monitoring radar device that outputs an I / Q detection signal can be used. Furthermore, even in an airport monitoring radar device that originally has a weather information detection device, the weather information detection device of this embodiment can be connected to a portion that outputs an I / Q detection signal.

  In this way, by connecting the weather information detection apparatus of the present embodiment to an existing radar receiver, weather information can be easily obtained without newly installing a weather radar. Moreover, it becomes possible to improve the performance of the weather information detection apparatus according to the prior art.

11 memory write / read control unit 12 buffer memory 13 memory read control unit 14 ground clutter memory 15 difference circuit 16 weather information detection circuit 21 IQ synthesis unit 22 canceller circuit 23 weather information detection circuit 31 weather Doppler pass filter circuit 32 weather information detection circuit 50 Radar receiver 51 I detection signal, Q detection signal 52 IQ synthesis circuit 53 I / Q signal 54 Interference removal circuit 55 I / Q signal 56 after interference wave removal 56 Weather Doppler pass filter circuit 57 Weather signal 58 Weather information detection circuit 59 Clock signal 60 Direction signal 61 Trigger signal 81 I detection signal input unit 82 Q detection signal input unit 83 Clock signal input unit 84 Direction signal input unit 85 Trigger signal input unit

Claims (7)

A weather Doppler pass filter circuit that inputs a radar reception signal and selectively passes a signal component corresponding to weather information;
A weather information detection circuit for generating weather detection data based on an output signal of the weather Doppler pass filter circuit;
The weather Doppler pass filter circuit is:
A meteorological information detection apparatus comprising a bandpass filter that selectively passes a frequency band corresponding to the weather information. In the meteorological information detection apparatus according to claim 1,
An IQ synthesis circuit unit for synthesizing an I (In-Phase) detection signal and a Q (Quadrature-Phase) detection signal in the radar reception signal and outputting them as an I / Q signal;
A meteorological information detection apparatus further comprising: an interference removal circuit unit for removing an interference radio wave component other than a reflected wave of the radio wave radiated by the Doppler radar from the I / Q signal and supplying the signal to the weather Doppler filter circuit unit. In the meteorological information detection apparatus according to claim 2,
The radar received signal is
A clock signal for synchronizing the operation of each component in the weather information detecting device;
A trigger signal for controlling the operation of each component in the weather information detecting device;
Including a direction signal for transmitting information related to the direction of the observation target detected by the radar receiver,
The IQ synthesis circuit unit, the interference cancellation circuit unit, the weather Doppler filter circuit unit, and the weather information detection circuit unit further input the clock signal, the trigger signal, and the direction signal. Weather information detection device. In the meteorological information detection apparatus in any one of Claims 1-3,
A meteorological information detection device further comprising a radar device for outputting the radar reception signal. In the meteorological information detection apparatus in any one of Claims 1-3,
A meteorological information detection apparatus, further comprising a radar reception signal input unit for inputting the radar reception signal. (A) inputting a radar reception signal and selectively passing a signal component corresponding to weather information;
(B) generating weather detection data based on the output signal obtained in step (a),
The step (a)
(A-1) A meteorological information detection method comprising a step of selectively passing a frequency band corresponding to the weather information. In the meteorological information detection method according to claim 6,
The step (a)
(A-2) combining an I (In-Phase) detection signal and a Q (Quadrature-Phase) detection signal in the radar reception signal and outputting as an I / Q signal;
(A-3) A weather information detection apparatus further comprising a step of removing an interference radio wave component from the I / Q signal before the step (a-1).

Images