JP6740112B2 - Signal processing device and weather radar device - Google Patents

Description

Embodiments of the present invention relate to a signal processing device and a weather radar device.

BACKGROUND ART Conventionally, there is known a weather radar device that observes a weather condition by transmitting a plurality of types of transmitted waves and analyzing reflected waves of the transmitted transmitted waves. When observing a short-range weather condition, the weather radar device transmits a short pulse transmission wave and measures the distance of a reflector or the like. The weather radar device transmits a long pulse transmission wave when observing a long-distance weather condition. The meteorological radar device compresses the time axis of a signal based on the reception of a reflected wave of a long pulse transmission wave, and measures the distance or the like of a reflector. The meteorological radar device creates an observation result by combining the meteorological situation in the short range and the meteorological situation in the long range.

When the time axis of the signal based on the reception of the reflected wave of the long pulse transmission wave is compressed, virtual images (side lobes) occur before and after the signal (main lobe) indicating the position of the reflector. As a result, when the reflected wave of the long pulse reflected by the object existing in the short distance area is compressed, a virtual image after compression may appear in the long distance area. In this case, the meteorological situation may be discontinuous at the boundary between the short distance area and the long distance area.

JP, 2011-191134, A

The problem to be solved by the present invention is to provide a signal processing device and a weather radar device capable of suppressing the discontinuity of weather conditions.

The signal processing device according to the embodiment includes a transmitter, a receiver, a first processor, a second processor, a predictor, a remover, and a combiner. The transmitter uses an antenna to transmit a first transmission wave having a predetermined pulse width and a second transmission wave having a pulse width longer than the predetermined pulse width. The receiver receives reflected waves of the first transmission wave and the second transmission wave. The first processing unit detects a first reception signal based on a reflected wave of the first transmission wave received by the reception unit. The second processing unit detects a second reception signal based on a reflected wave of the second transmission wave received by the reception unit. The prediction unit is included in a reflected wave of the second transmission wave reflected by an object existing in a predetermined short-distance region, based on the first reception signal detected by the first processing unit. Predict the signal of the sidelobe component. The removing unit removes the signal of the side lobe component predicted by the predicting unit from the second received signal detected by the second processing unit. The combining unit combines the first received signal and the second received signal from which the side lobe component signal has been removed by the removing unit.

The block diagram which shows an example of the weather radar apparatus 1 of embodiment. The figure which shows the relationship between the position of the weather radar apparatus 1 of embodiment, and the range which observes a weather condition. The figure which shows the time relationship which receives the reflected wave with respect to having transmitted the transmission wave of a short pulse width by the weather radar apparatus 1 of embodiment. The figure which shows the time relationship which receives the reflected wave with respect to having transmitted the transmission wave of a long pulse width by the weather radar apparatus 1 of embodiment. The figure explaining suppressing side lobe SL1 by the weather radar apparatus 1 of embodiment.

Hereinafter, a signal processing device and a weather radar device according to embodiments will be described with reference to the drawings.

FIG. 1 is a block diagram showing an example of a weather radar device 1 of the embodiment. The weather radar device 1 includes, for example, an antenna unit 10, a transmission/reception switching unit 20, a transmission signal generation unit 30, a radar signal processing unit 40, and an analysis unit 50.

The antenna unit 10 is, for example, a phased array antenna. The phased array antenna includes a large number of antenna elements arranged in a plane and a large number of phase shifters connected to the respective antenna elements. Further, the antenna unit 10 includes a transmission amplifier that amplifies a transmission signal. Further, the antenna unit 10 includes a reception amplifier that amplifies a reception signal, a reception filter, and the like.

The antenna unit 10 transmits a transmission beam adjusted to have a predetermined beam width in the elevation direction and the azimuth direction. The antenna unit 10 radiates a transmission beam, electronically scans it, and mechanically rotates the phased array antenna to observe surrounding weather conditions.

The transmission/reception switching unit 20 switches the timing of supplying the transmission signal to the antenna unit 10 and the timing of supplying the reception signal to the radar signal processing unit 40.

The transmission signal generation unit 30 is, for example, an exciter that generates a transmission signal having a predetermined frequency. The transmission signal generation unit 30 functions as a transmission unit that transmits a transmission wave using the antenna unit 10. The transmission signal generation unit 30 includes, for example, a short pulse signal generation unit 32 and a long pulse signal generation unit 34. The short pulse signal generation unit 32 generates a short pulse signal for transmitting a transmission wave having a predetermined pulse width (hereinafter, short pulse width). The long pulse signal generation unit 34 generates a long pulse signal for transmitting a transmission wave having a pulse width (hereinafter, long pulse width) longer than a predetermined pulse width. The transmission signal generation unit 30 causes the antenna unit 10 to repeatedly transmit, for example, a short pulse width transmission wave and a long pulse width transmission wave at predetermined intervals.

FIG. 2 is a diagram showing the relationship between the position of the weather radar device 1 of the embodiment and the range for observing weather conditions. The short pulse signal is a signal for generating a transmission wave from the weather radar device 1 for measuring a weather condition at a predetermined short distance D1. The predetermined short distance D1 is, for example, an area including a distance within a range of 4 to 10 [Km] from the weather radar device 1 (hereinafter, a short distance area (first area)). The short pulse width is 1.33 μsec, for example. The long pulse signal is a signal for generating a transmission wave for measuring a weather condition in a range of a distance D2 farther from the weather radar device 1 than in a short range area (hereinafter, a long range area (second area)). The long-distance region is, for example, a region that is far from the short-distance region and that can be detected by the weather radar device 1 as a reflected wave in which a long pulse signal is reflected by an object. The long pulse width is, for example, 20 to 80 μsec.

Returning to FIG. The radar signal processing unit 40 includes, for example, a short pulse signal processing unit 41, an echo generation prediction unit 42, a long pulse signal processing unit 43, an echo removal unit 44, and a signal synthesis unit 45. These functional units are realized by a processor such as a CPU (Central Processing Unit) executing a program stored in a program memory. Further, some or all of these functional units may be realized by hardware such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), or FPGA (Field-Programmable Gate Array). It may be realized by cooperation of software and hardware.

The short pulse signal processing unit 41 acquires a reception signal (hereinafter, short pulse reception signal) generated by receiving a reflected wave of a transmission wave having a short pulse width by the antenna unit 10. The short pulse reception signal is a signal representing the position of an object existing in the short distance area. The short pulse signal processing unit 41 performs A/D conversion processing and the like on the short pulse reception signal and supplies the signal to the signal synthesis unit 45.

The echo generation prediction unit 42, based on the short pulse reception signal supplied from the short pulse signal processing unit 41, a side lobe included in a reflected wave of a short pulse width transmission wave reflected by an object existing in a short distance area. The position and intensity of the signal of the component are predicted (prediction unit). The echo generation prediction unit 42 determines that the side lobe component is closer to the boundary with the short-distance area in the long-distance area as the position of the object existing in the short-distance area is closer to the long-distance area in the short-distance area. Predict to occur. Furthermore, the echo generation prediction unit 42 predicts that the higher the strength of the transmission wave having the short pulse width, the higher the strength of the signal of the side lobe component. Further, the echo generation prediction unit 42 predicts that the higher the compression ratio on the time axis in the long pulse signal processing unit 43, the higher the signal strength of the side lobe component. Further, the echo occurrence prediction unit 42 may predict the position and intensity of the side lobe component based on the modulation method of the transmission signal in the transmission signal generation unit 30.

The echo occurrence prediction unit 42 may calculate the position and intensity of the side lobe SL1 by a function. The echo generation prediction unit 42 calculates the side lobe width as a function of the modulation method (MD) of the transmission signal, the pulse width (T) of the transmission wave, and the modulation width (B), for example, as shown in the following equation. May be.
[SL]＝function (MD,B,T)

Further, generally, the waveform after pulse compression (range side lobe) is expressed by the following equation 1. In Formula 1, * represents a conjugate complex number. In Expression 1, r(t) is a received signal (the received signal is a reflection of the transmitted signal x(t), and it is considered that the intensity and delay of the transmitted signal are changed), and Δt is. Sampling interval (≦1/Δf), N is T/Δt (T is transmission pulse width), and x ^* (iΔt) is a coefficient of the multiplier of the transversal filter.

The transmission signal modulation method (MD) is a frequency modulation method (LFM (Liner Frequency Modulation)) in which the frequency of the transmission signal is changed linearly, or a frequency modulation in which the reference wave during pulse compression is multiplied by a window function on the time axis. Examples thereof include a system (LFM+time axis window function) and a frequency modulation method in which a window function using a COS function is applied. The pulse width (T) of the transmission width is the pulse width of the transmission signal. The modulation width (B) is the width of change in the frequency of the transmission signal during the transmission of one transmission pulse having a long pulse width. The modulation width (B) is, for example, “2.5 MHz” when the frequency of the transmission signal is changed with a width of 2.5 MHz while transmitting the transmission wave of 72 μsec.

The long pulse signal processing unit 43 acquires a reception signal (hereinafter, long pulse reception signal) generated by receiving a reflected wave of a transmission wave having a long pulse width by the antenna unit 10. The long pulse reception signal is a signal representing the position of an object existing in the short distance area and the long distance area. The long pulse signal processing unit 43 excludes a signal for detecting an object in a short distance area from the long pulse reception signal. That is, the long pulse reception signal includes a signal for detecting an object existing in a long distance area. The long pulse signal processing unit 43 performs A/D conversion processing and pulse compression processing on the long pulse reception signal. The pulse compression processing compresses the time axis of the long pulse reception signal. As a result, the long pulse signal processing unit 43 increases the signal strength and the position measurement accuracy.

The echo removing unit 44 removes the signal of the side lobe component predicted by the echo generation predicting unit 42 from the long pulse reception signal detected by the long pulse signal processing unit 43 (removing unit).

The signal synthesis unit 45 synthesizes the short pulse reception signal acquired by the short pulse signal processing unit 41 and the long pulse reception signal from which the side lobe component signal has been removed by the echo removal unit 44.

The analysis unit 50 analyzes the weather condition based on the received signals combined by the signal combining unit 45. The analysis unit 50 displays the weather condition, for example, based on the received signal. The display device 50, for example, generates display data in which the display color is changed based on the signal strength, and generates an image representing the weather condition. Thereby, the analysis unit 50 can present the weather conditions of the short-distance area and the long-distance area from the weather radar device 1 to the user.

FIG. 3 is a diagram showing a temporal relationship in which a reflected wave is received in response to the transmission wave having a short pulse width transmitted by the weather radar device 1 of the embodiment. As shown in the upper diagram of FIG. 3, the weather radar device 1 transmits a transmission wave having a short pulse width in the transmission period (Ts−1) from time t0. After that, the weather radar device 1 receives the reflected wave of the transmitted wave having the short pulse width in the reception period Tr-1 from the time t1 to the time t2. For example, when the object OB is located at a distance D1 from the weather radar device 1, the weather radar device 1 receives the reflected wave of the transmission wave having the short pulse width at the time t2. As a result, the weather radar device 1 can acquire a short pulse reception signal having a high detection voltage at the distance D1, as shown in the lower diagram of FIG.

FIG. 4 is a diagram showing a temporal relationship in which a reflected wave is received in response to transmission of a long pulse width transmitted wave by the weather radar device 1 of the embodiment. As shown in the upper diagram of FIG. 4, the weather radar device 1 transmits a transmission wave having a long pulse width in the transmission period (Ts-2) from time t0. After that, the weather radar device 1 receives the reflected wave of the transmission wave having the long pulse width in the reception period Tr-2 from time t11 to time t13. For example, when the object OB12 is located at a distance D2 from the weather radar device 1, the weather radar device 1 receives the reflected wave of the transmission wave having the long pulse width at time t13. As a result, the weather radar device 1 can acquire a long pulse reception signal having a high detection voltage at the distance D2, as shown in the lower diagram of FIG.

As shown in the upper diagram of FIG. 4, it is assumed that an object OB is located at a distance D1 from the weather radar device 1 and an object OB11 is located at a distance D11 from the weather radar device 1. The transmitted wave having a short pulse width and the transmitted wave having a long pulse width are reflected by the object OB and arrive at the weather radar device 1 as reflected waves (SP, LP). The transmitted wave having a long pulse width is reflected by the object OB11 and arrives at the weather radar device 1 as a reflected wave (LP). The transmitted wave having a short pulse width disappears without reaching the object OB11.

When the long pulse reception signal based on the reflection by the object OB is compressed, as shown in the lower diagram of FIG. 4, the side lobes SL1 and SL2 are arranged before and after the main lobe ML1 appearing at the position corresponding to the distance D1 in terms of distance. Appears. Therefore, it can be seen that the presence of the side lobe SL1 results in a high detection voltage even though there is no object in the long-distance region from the distance D1 to the distance D11. From the above, it can be seen that the object detection results are continuous near the boundary between the short-distance area and the long-distance area.

Further, it can be seen that the side lobe SL1 and the main lobe ML2 that appears by being reflected by the object OB11 overlap each other. From the above, it can be seen that the side lobe SL1 results in the object as if it exists from D1 to D11, even though the object OB11 exists at the position of the distance D11. As a result, the position accuracy with which the object is observed may deteriorate. It should be noted that the side lobes located in front of and behind the main lobe ML2 are not shown.

FIG. 5: is a figure explaining suppressing the side lobe SL1 by the weather radar apparatus 1 of embodiment. The echo generation prediction unit 42 predicts the position and intensity of the side lobe SL1 that appears due to the object OB existing in the short distance area. The echo removing unit 44 removes the signal strength at the predicted position of the side lobe SL1 from the signal strength at the corresponding position in the long distance area. As a result, the echo removing unit 44 can lower the signal strength as compared with the side lobe SL1 like the side lobe SL1#.

According to the weather radar device 1 described above, the reflected waves of the transmitted wave having the short pulse width and the transmitted wave having the long pulse width are received, and reflected by the object existing in the short range based on the short pulse received signal. The signal of the side lobe component included in the long pulse reception signal is predicted. Since the weather radar device 1 removes the predicted side lobe component signal from the long pulse reception signal, even if the side lobe included in the short pulse reception signal appears in the long-distance region, the long pulse reception signal is received. Sidelobe components can be removed from the signal. As a result, according to the meteorological radar device 1, it is possible to prevent the continuity of the meteorological situation from being impaired in the vicinity of the boundary between the short distance area and the long distance area.

In addition, the weather radar device 1 predicts that the side lobe component signal is generated at a position closer to the short-distance region in the long-distance region as the position of the object existing in the short-distance region is closer to the long-distance region. It is possible to suppress the influence of the side lobe at a position close to the short distance region in the long distance region.

Furthermore, the weather radar device 1 predicts that the strength of the signal of the side lobe component is higher as the strength of the transmission wave having the short pulse width is higher, so that the influence of the side lobe in the long-distance region can be further suppressed. ..

Further, according to the meteorological radar device 1, the higher the compression ratio of the time axis in the long pulse signal processing unit 43, the higher the signal strength of the side lobe component is predicted. Therefore, in order to increase the position accuracy in the long distance region, Even if the ratio of pulse compression is increased, it is possible to effectively suppress the influence of the side lobes in the long distance region.

According to at least one embodiment described above, the antenna 10 is used to transmit a transmission wave having a short pulse width and a transmission wave having a long pulse width. The antenna unit 10 which receives the reflected wave of the transmitted wave having the pulse width, the short pulse signal processing unit 41 which detects the short pulse received signal based on the reflected wave of the transmitted wave which has the short pulse width, and the transmitted wave of the long pulse width A long pulse signal processing unit 43 that detects a long pulse reception signal based on the reflected wave, and a long pulse signal reflected by a transmission wave having a long pulse width that is reflected by an object existing in a short distance area based on the short pulse reception signal. Since it has the echo generation prediction unit 42 that predicts the side lobe component signal and the echo removal unit 44 that removes the predicted side lobe component signal from the long pulse reception signal, the side lobe affects the weather conditions. Discontinuity can be suppressed.

Although some embodiments of the present invention have been described, these embodiments are presented as examples 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 modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and the gist of the invention.

DESCRIPTION OF SYMBOLS 1... Meteorological radar device, 10... Antenna part, 20... Transmission/reception switching part, 30... Transmission signal generation part, 32... Short pulse signal generation part, 34... Long pulse signal generation part, 40... Radar signal processing part, 41... Short Pulse signal processing unit, 42... Echo generation predicting unit, 43... Long pulse signal processing unit, 44... Echo removing unit, 45... Signal combining unit, 50... Analyzing unit

Claims (7)

A transmitting unit for transmitting a first transmission wave having a predetermined pulse width and a second transmission wave having a pulse width longer than the predetermined pulse width using the antenna;
A receiver for receiving reflected waves of the first transmitted wave and the second transmitted wave,
A first processing unit for detecting a first reception signal based on a reflected wave of the first transmission wave received by the reception unit;
A second processing unit that detects a second reception signal based on a reflected wave of the second transmission wave received by the reception unit;
A signal of a side lobe component included in a reflected wave of the second transmitted wave reflected by an object existing in a predetermined short-distance area based on the first received signal detected by the first processing unit. A prediction unit that predicts
A removing unit that removes the signal of the sidelobe component predicted by the predicting unit from the second received signal detected by the second processing unit;
A combiner that combines the first received signal and the second received signal from which the side lobe component signal has been removed by the remover;
A signal processing device comprising: The prediction unit is such that the position of the object existing in the short-distance area is closer to the long-distance area farther from the own device than the short-distance area in the short-distance area. It is predicted that the signal of the side lobe component will occur at a position close to
The signal processing device according to claim 1. The prediction unit predicts that the higher the strength of the first transmission wave, the higher the strength of the signal of the side lobe component,
The signal processing device according to claim 1. The second processing unit detects the second reception signal obtained by compressing the time axis of the signal indicating the intensity of the reflected wave of the second transmission wave received by the reception unit.
The signal processing device according to any one of claims 1 to 3. The prediction unit predicts that the higher the compression ratio of the time axis in the second processing unit, the higher the signal strength of the side lobe component.
The signal processing device according to claim 4. The synthesizing unit synthesizes the first received signal and a signal representing a position of an object existing in a far-distance area farther from the device than the short-distance area in the second received signal.
The signal processing device according to claim 1. The signal processing device according to any one of claims 1 to 6,
A weather radar device, comprising: an analysis unit that analyzes a weather condition based on the signals synthesized by the synthesis unit.

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