Patent Description:
Conventionally, regarding radars for ships used for monitoring the periphery of the own ship, magnetron radars using magnetron elements in transmission elements have been the mainstream.

Compared to the magnetron radars, solid-state radars, whose development started in rather recent years, use semiconductors as transmission elements, and have the advantages of having a narrow bandwidth, a miniaturized size, and being maintenance-free. However, due to the characteristics of the transmission element, the transmission peak power of a solid-state radar is far lower than the transmission peak power of a magnetron radar. Therefore, in order to observe a remote target, the solid-state radar may transmit a pulse-like signal whose frequency is modulated (chirped pulse signal) to pulse-compress waves reflected from the target and improve the S/N ratio.

In addition, the radars for ships are also used to observe waves in the periphery of the own ship, in addition to monitoring the periphery of the own ship, and are referred to as wave radars for wave observation. The wave radars analyze the reflected waves of the transmission signals returned from the sea level in the periphery of the own ship, and output wave information, such as wave heights, periods, wavelengths, wave directions, etc., of the waves. In addition, wave radars have been developed by using magnetron radars.

In the case of remote monitoring, in a magnetron radar, a transmission signal is set as a non-modulated signal (long pulse) composed of a long pulse width for long distance observation. Meanwhile, in the case of wave observation in the vicinity of the own ship, in order to obtain a sufficient resolution with respect to waves with a short wavelength, transmission signals are mostly set as non-modulated signals (short-pulse or middle-pulse) of a short pulse width for short distance to intermediate distance observation. Therefore, in the case where wave observation and periphery monitoring are performed at the same time by using short pulse or middle pulse signals in the transmission signals, the magnetron radar is unable to observe a remote target. As a result, the magnetron radar is unable to sufficiently fulfill the purpose of periphery monitoring.

For such reasons, a user who performs periphery monitoring including remote monitoring in wave observation needs to be respectively provided with a radar for wave observation and a radar for target observation.

The purpose of the disclosure relates to providing a solid-state radar device capable of fulfilling the functions of wave observation as well as periphery monitoring including remote monitoring at the same time.

In order to solve the above issue, a solid-state radar device according to the disclosure includes: a transmission/reception unit transmits and receives radio wave signals comprising a modulated signal and a non-modulated signal, which are pulse signals whose frequencies are different from each other; a frequency filter unit respectively separates the modulated signal and the non-modulated signal from the received radio wave signals based on the frequencies by using band pass filters; a pulse compression unit generating a pulse-compressed signal by pulse-compressing the modulated signal; a first echo image generation unit generates a first echo image based on the non-modulated signal and the pulse-compressed signal; a wave analysis unit analyzes ocean wave information based on one of the non-modulated signal and the pulse-compressed signal; and a display signal generation unit generates a display signal comprising the first echo image and/or the ocean wave information.

In addition, a refresh rate for generating the first echo image for each azimuth may be more frequent than a refresh rate for analyzing the ocean wave information.

In addition, the transmission/reception unit further comprises a rotating antenna, and the wave analysis unit may analyze the ocean wave information by analyzing a scan image comprising the first echo image corresponding to at least one rotation of the antenna.

In addition, the first echo image may be divided into a plurality of regions in accordance with a distance from a transmission location, and the regions may be formed from an image based on at least one of the non-modulated signal and the pulse-compressed signal. The wave analysis unit may analyze, among the regions, a region formed by one of the non-modulated signal and the pulse-compressed signal.

In addition, at least one of the regions may be formed from a synthesized image in which a formation ratio of the non-modulated signal and the pulse-compressed signal is changed in accordance with distance.

In addition, the display signal generation unit may generate a display signal in which the first echo image and the the ocean wave information are displayed at a same time on a same screen.

In addition, the display signal generation unit may generate a display signal in which information of at least a portion of the the ocean wave information is superimposed on the first echo image.

In addition, the display signal generation unit may generate a display signal in which an analysis region, which is a region for analyzing the ocean wave information, is superimposed on the first echo image.

In addition, the solid-state radar device may further include an analysis region input unit which receivies an input for changing at least one of a number, a location, and a size of the analysis region.

In addition, the solid-state radar device may further include a heading acquisition unit, on which the solid-state radar is to be installed, whch calculates a heading of an own ship. The ocean wave information may include information of a wave direction. The display signal generation unit may generate a display signal indicating a relative angle between the wave direction and the heading.

In addition, the display signal generation unit may generate a display signal of a wave image based on the ocean wave information.

In addition, the solid-state radar device may further include a second echo image generation unit which generates a second echo image based on one of the non-modulated signal and the pulse-compressed signal. The wave analysis unit may calculate the ocean wave information by analyzing a region of a portion of the second echo image.

In addition, the transmission/reception unit may further include an antenna that rotates, and the wave analysis unit may calculate the ocean wave informaiton by analyzing a scan image composed of the second echo image corresponding to one rotation of the antenna.

According to the configuration, by transmitting the radio wave signals whose frequencies are different and respectively separating the radio wave signals from reflected waves, it is possible for the solid-state radar device to fulfill wave observation and monitoring at the same time.

According to the disclosure, it is possible to fulfill the functions of wave observation as well as monitoring including remote monitoring at the same time by using a single solid-state radar device.

A solid-state radar device according to the embodiment of the disclosure is described with reference to the drawings. The solid-state radar device in the embodiment is used as a radar for a ship, such as a merchant ship, a fishing ship, a pleasure boat, etc..

In the following, the basic configuration and the basic operation of the disclosure are described. <FIG> is a diagram illustrating the configuration of a solid-state radar device <NUM> according to the embodiment.

<FIG> illustrates the configuration of a transmission/reception unit <NUM>. The transmission/reception unit <NUM> is formed by an antenna <NUM>, a circulator <NUM>, a transmission unit <NUM>, and a reception unit <NUM>, etc..

The transmission unit <NUM> alternately generates, as transmission signals, a modulated signal, which is a pulse signal whose frequency is modulated, and a non-modulated signal, which is a non-modulated pulse signal, and outputs the transmission signals to the circulator <NUM>. At this time, the transmission unit <NUM> generates, as the transmission signals whose frequencies are different, the modulated signal and the non-modulated signal, so that the frequency bands do not overlap each other. In addition, while not shown in the drawings, the transmission unit <NUM> outputs a portion of the transmission signal relating to the modulated signal to a pulse compression unit <NUM>.

The circulator <NUM> transmits the transmission signals from the transmission unit <NUM> to the antenna <NUM>, and outputs reception signals received from the antenna <NUM> to the reception unit <NUM>.

The antenna <NUM> is formed by arranging patch antennas, etc., in a row, and rotates thereby being able to orientate a transmission/reception surface in all directions (<NUM> degrees) of a parallel surface with respect to a surface where the solid-state radar device <NUM> is disposed. The antenna <NUM> radiates the transmission signals with respect to an external space in various azimuths while rotating. A portion of the transmitted transmission signals is reflected by a reflection body such as an object, etc., present at sea level or in the sea. In addition, the antenna <NUM> receives, as the reception signals, a portion of the transmission signals that are reflected while rotating.

The reception unit <NUM> performs a reception process detecting the reception signals by using a double superheterodyne method and, after amplification by an amplifier, converting analog signals into digital signals by using an A/D converter.

<FIG> illustrates the configuration of a frequency filter unit <NUM>. The frequency filter unit <NUM> is composed of two band-pass filters (BPF) separating the modulated signal and the non-modulated signal based on frequencies.

The reception signals subjected to the reception process in the reception unit <NUM> are respectively output to a BPF <NUM> and a BPF <NUM>. The BPF <NUM> extracts the one with a lower frequency between the modulated signal and the non-modulated signal, and the BPF <NUM> extracts the other one with a higher frequency. Here, whether each of the BPF <NUM> and the BPF <NUM> extracts the modulated signal and the non-modulated signal depends on the setting of the frequencies of the modulated signal and the non-modulated signal. The two band-pass filters may also be formed from a low-pass filter (LPF) and a high-pass filter (HPF), as long as the filters are able to separate the modulated signal and the non-modulated signal.

The modulated signal extracted by one of the band-pass filters is output to the pulse compression unit <NUM>. The non-modulated signal extracted by the other of the band-pass filters is output to a first echo image generation unit <NUM>.

The pulse compression unit <NUM> converts the modulated signal into a pulse-compressed signal by performing a pulse compression process, and outputs the pulse-compressed signal to the first echo image generation unit <NUM>. Here, the pulse compression process may be a conventionally known process, such as a matched filter method.

The first echo image generation unit <NUM> generates, as a first echo image, a sweep image based on sweep data, and outputs the sweep image to a wave analysis unit <NUM> and a display signal generation unit <NUM>. Here, the sweep data is the signal data of a specific direction generated from the non-modulated signal and the pulse-compressed signal corresponding to consecutive transmission pulses. In addition, the sweep image is an image in which the distance from an own ship <NUM> to a particular distance is pixelated based on the sweep data of the modulated signal, and a distance that is further is pixelated based on the sweep data of the pulse-compressed signal, the azimuth direction being one pixel, and the distance direction being a particular number of pixels.

The wave analysis unit <NUM> generates an image of one polar coordinate system from multiple sweep images equivalent to one scan. In addition, the wave analysis unit <NUM> converts the image of the polar coordinate system into one scan image, which is an image of a Cartesian coordinate system with the own ship <NUM> being at the center. Here, "scan" refers to an operation of rotating the antenna <NUM> degrees while performing transmission/reception of radio wave signals. Radio wave signals are a general term referring to the transmission signal and the reception signal, which is the modulated signal or the non-modulated signal, and the reflected waves of the transmission signal.

Then, the wave analysis unit <NUM> sets an analysis region <NUM>, which is a portion of the region of the same pixel size, from a region of the area generated by the non-modulated signals or the pulse-compressed signals of multiple scan images that are consecutive in time. Here, <FIG> is an example in which the analysis region <NUM> is set in a region composed of the non-modulated signal in one scan image. The intensity information of multiple images corresponding to the location of the analysis region <NUM> is handled as a three-dimensional matrix. In addition, the wave analysis unit <NUM> calculates, as an analysis result (which is also referred to as ocean wave information) such as the wave height, the period, the wavelength, and the direction, etc., based on the result of a Fourier conversion on the three-dimensional matrix, and outputs the analysis result to the display signal generation unit <NUM>. In this example, the period (which is also referred to as reflesh rate) for calculating the analysis result is longer than the period for generating the sweep image.

The display signal generation unit <NUM> generates a display signal of a screen containing the sweep image and the wave analysis result. The solid-state radar device <NUM> may further include a display unit displaying the display signal generated by the display signal generation unit <NUM>.

In the following, the effects in the basic configuration are described.

The transmission unit of the magnetron radar has a magnetron element, and can transmit a pulse signal with a high peak power with respect to a solid-state element of the solid-state radar. Meanwhile, due to the characteristics of the solid-state element, the peak power of the transmission signal is low, so the transmission unit of the solid-state radar cannot transmit a pulse signal with power equivalent to that of the magnetron radar. Therefore, the solid-state radar cannot secure a detection distance by using the same pulse width as the magnetron radar. Therefore, the transmission unit of the solid-state radar transmits a temporally long pulse signal (modulated signal) whose frequency is modulated, ensures the S/N ratio by performing the pulse compression process at the time of reception, and secures the detection distance.

Here, in the solid-state radar, during the transmission of the modulated signal, a portion of the transmission signal is leaked to the reception unit <NUM>. Therefore, the solid-state radar cannot receive the reflected wave of the modulated signal during the transmission of the modulated signal. Since the modulated signal of the solid-state radar is based on the assumption that the S/N ratio improves due to the pulse compression process, the modulation signal of the solid-state radar is longer than the transmission signal of the magnetron radar. As a result, the time during which the solid-state radar cannot receive the modulated signal is longer, and such time becomes the time during which the target in the vicinity of the own ship cannot be observed. In the following, the region in which the reflected wave of the modulated signal cannot be received is referred to as a dead region. For example, in the case where the pulse width of the modulated signal is about <NUM>, the dead region is in a range with a radius of about <NUM> from the own ship.

Here, the distance of the dead region from the own ship <NUM> is short, and the radio wave signals do not relatively attenuate when going back and forth from the transmission unit to the target. Therefore, the solid-state radar transmits non-modulated signals whose averaged power is low and pulse width is short, and interpolates the dead region of the modulated signal by generating an echo image of the dead region based on the reception signals of the non-modulated signals.

Accordingly, by using the modulated signal as well as the non-modulated signal in the transmission signal, the solid-state radar can observe targets from the vicinity of the own ship to a remote location.

Due to the characteristics of the magnetron element, it is difficult for the magnetron radar to appropriately adjust the frequency of the transmission signal. Meanwhile, the solid-state radar can set respectively different frequencies for the transmission signals of the modulated signal and the non-modulated signal, and the respective reception signals thereof can be easily separated by using the band-pass filters.

Here, assuming that the magnetron radar alternately transmits a short pulse and a long pulse, the magnetron radar may serve as a combined radar for wave analysis and periphery monitoring. More specifically, as shown in (A) of <FIG>, the magnetron radar can analyze waves based on the reception signal of a short pulse and generate the echo image of a remote location based on the reception signal of a long pulse.

Since the transmission signal is leaked to the reception side, the magnetron radar cannot receive one of the long pulse signal and the short pulse signal during transmission of the other. Therefore, in the combined configuration as the above for the magnetron radar, in order to individually secure the reception time of each transmission pulse, the transmission unit may decrease the pulse repetition frequency (PRF), which is the frequency of repeating each transmission pulse. However, the decrease in PRF decreases the respective azimuth resolutions of the short pulse and the long pulse as well as the hit number of the target, leading, in particular, to a decrease in the ability of detecting a remote target.

Meanwhile, the solid-state radar may easily change the frequency of the transmission signal, so the solid-state radar can consecutively transmit the modulated signal and the non-modulated signal of different frequencies. Therefore, as shown in (B) of <FIG>, by separating the reception signals of the modulated signal and the non-modulated signal by using the band-pass filters, the other of the modulated signal and the non-modulated signal can be received during transmission of the other without the concern of leakage of the transmission signal. Accordingly, the solid-state radar does not need to decrease the PRF of the transmission signal.

Here, the wave analysis unit <NUM> of the embodiment calculates the analysis result by analyzing the region of a portion of the image composed of the first echo image generated in the first echo image generation unit <NUM>. Therefore, it is not necessary for the transmission unit <NUM> to separately transmit the transmission signal used for analyzing the waves in the vicinity of the own ship and the transmission signal used for generating the display signal as the image of the periphery of the own ship. Accordingly, in the embodiment which analyzes the ocean wave information, it is not necessary for the solid-state radar to decrease the PRF of the transmission signal.

The wave analysis unit <NUM> analyzes the ocean wave information in a region formed by one of the non-modulated signal and the pulse-compressed signal in the first echo image. By setting the analysis region <NUM> so that the portions formed from the respective signals of the non-modulated signal and the pulse-compressed signal are not repetitively included, the wave analysis unit <NUM> can analyze the ocean wave information without generating another echo image for wave analysis. This is because the non-modulated signal and the pulse-compressed signal have different pulse properties, and the echo images respectively composed of the non-modulated signal and the pulse-compressed signal also have different properties. By setting the pulse width of the non-modulated signal to a very short pulse width for the analysis on the ocean wave information, the analysis result of the ocean wave information becomes highly accurate.

<FIG>, which is the flowchart according to the embodiment of the disclosure, is described.

The transmission/reception unit <NUM> generates the transmission signals of the modulated signal and the non-modulated signal (Step S1). Then, the transmission/reception unit <NUM> performs a transmission process which radiates the generated transmission signals to the external space via the circulator <NUM> and the rotating antenna <NUM> (Step S2). Then, the transmission/reception unit <NUM> performs a reception process which receives the reflected waves that are the transmission signals reflected from a reflection body via the antenna <NUM> (Step S3).

The frequency filter <NUM> respectively extracts the modulated signal and the non-modulated signal from the reception signals by using the band-pass filters (Step S4). The frequency filter unit <NUM> outputs the modulated signal in the reception signals to the pulse compression unit <NUM> (Step S5). If the reception signal is not the modulated signal, that is, if the reception signal is the non-modulated signal, the frequency filter unit <NUM> inputs the reception signal to the first echo image generation unit <NUM> (Step S5). The pulse compression unit <NUM> performs a pulse compression process on the modulated signal, and outputs the pulse-compressed signal to the first echo image generation unit <NUM> (Step S6).

The first echo image generation unit <NUM> generates an echo image based on the sweep data of the modulated signal and the non-modulated signal (Step S7). Then, in the case where the first echo image is used in the wave analysis unit <NUM>, the first echo image generation unit <NUM> outputs the first echo image to the wave analysis unit <NUM> (Step S8). In addition, in the case where the first echo image is not used in the wave analysis unit <NUM>, the second echo image generation unit <NUM> generates a second echo image, and outputs the second echo image to the wave analysis unit <NUM> (Step S9).

The wave analysis unit <NUM> performs an analysis on the ocean wave information based on at least one of the non-modulated signal and the pulse-compressed signal, and outputs a wave analysis result, such as the wave height, the period, the wavelength, and the direction to the display signal generation unit <NUM> (Step S10).

The display signal generation unit <NUM> generates a display signal displaying the wave analysis result and the first echo image (Step S11).

In the following, various detailed embodiments are described.

At the time of generating the first echo image, the first echo image generation unit <NUM> can generate the first echo image by dividing into multiple regions with respect to the distance direction. In <FIG>, the region in the vicinity of the own ship is formed by the non-modulated signal, and the remote region of the own ship is formed by the pulse-compressed signal. In addition, the wave analysis unit <NUM> sets the analysis region <NUM>, among the regions, in the region formed by the non-modulated signal in the vicinity of the own ship, and analyzes the ocean wave information.

In the region due to synthesis in <FIG>, the first echo image generation unit <NUM> generates the first echo image having a region formed due to synthesis of the non-modulated signal and the pulse-compressed signal between the regions respectively formed by the non-modulated signal and the pulse-compressed signal among the multiple divided regions. The process for the synthesis is a process in which the formation ratio of the non-modulated signal decreases as the distance from the transmission/reception unit increases. Accordingly, the first echo image is a seamless image in which the joined part of the regions of the two signals is not prominent.

In a display screen <NUM> shown in <FIG>, an image <NUM> of the periphery of the own ship based on the first echo image is provided on the left, and the information of the wave height, the period, and the wave direction, which is a portion of the analysis result, is provided in a wave information area <NUM> on the right, and the display screen <NUM> displays the periphery image <NUM> and the wave information area <NUM> on the same display screen at the same time. In addition, the display screen <NUM> superimposes the analysis region <NUM> on the periphery image <NUM> based on the first echo image. In addition, the display screen <NUM> displays a wave vector <NUM>, which is a portion of the analysis result, on the periphery image <NUM>. Besides, the display signal generation unit <NUM> can generate two types of display signals displaying the first echo image and the analysis result on two respectively different display screens.

A solid-state radar device <NUM> in <FIG> further includes a heading acquisition unit <NUM>. The heading acquisition unit <NUM> calculates the heading of the own ship from sensor information of a GPS sensor or a gyrocompass acquiring the location information of the own ship, and outputs the heading to the display signal generation unit <NUM>. The display screen <NUM> in <FIG> is a screen displaying the information of a relative angle <NUM> between the wave direction, which is a portion of the wave analysis result, and the heading of the own ship.

The wave analysis unit <NUM> may also perform a Fourier conversion on the three-dimensional matrix of the analysis region <NUM>, and perform an inverse Fourier conversion after removing components other than waves through filtering based on the frequency of the waves of the analysis result, thereby generating, as a wave image, a two-dimensional image that emphasizes the ocean wave information as compared to a normal echo. The wave image is a three-dimensional image with which the wave height, the wavelength, and the wave direction can be grasped at a glance from the appearance, and is stored in advance with the values of the ocean wave information. The wave analysis unit <NUM> may also extract the stored wave image having the values of the ocean wave information close to the analysis result. In addition, the display signal generation unit <NUM> can generate a display signal in which the wave image and the first echo image are superimposed.

As shown in <FIG>, the solid-state radar device <NUM> can further include an analysis region input unit <NUM>. The wave analysis unit <NUM> changes the location, the size, and the number of the analysis region <NUM> in correspondence with a user input.

A portion of the transmission signals transmitted by the antenna <NUM> is reflected from the sea level, and the reflected waves of a portion thereof are received by the antenna <NUM>. The strength of the received reflected wave depends on the incident angle with respect to the sea level, and the strength is higher when the distance from the transmission/reception unit <NUM> is shorter. Therefore, the ocean wave information mostly includes the reflected waves near the vicinity of the own ship.

Here, in order to more clearly reflect a target such as another ship, it is common to perform some signal processes on the echo image of the radar. One of such processes is a sensitivity time control (STC) process, which is a method for suppressing sea level reflection (sea clutter). The STC process is a process for conversion into a uniform image regardless of distance by suppressing the influence of the nearby sea level reflection by decreasing the gain with respect to a strong reflected wave from a short distance.

Meanwhile, the echo image of the radar used for wave analysis analyzes the ocean wave information included in the reflected waves, an STC process is normally not performed. This is because sea clutter is the analysis target in the wave analysis unit <NUM>, and it is not necessary to attenuate the ocean wave information.

Therefore, the first echo image generation unit may also generate the first echo image in which a noise suppression process, etc., same as that performed for display is not performed, and output the first echo image to the wave analysis unit <NUM>.

In <FIG>, the solid-state radar device <NUM> further includes a second echo image generation unit <NUM>. The second echo generation unit <NUM> generates, in place of the first echo image, the second echo image used in the wave analysis unit <NUM>, and outputs the second echo image to the wave analysis unit <NUM>. The second echo image is formed by at least one of the non-modulated signal and the pulse-compressed signal. In addition, the wave analysis unit <NUM> sets the analysis region <NUM> in the region formed by one of the non-modulated signal and the pulse-compressed signal in the region of the second echo image and analyzes the ocean wave information. Accordingly, the second echo image generation unit <NUM> can generate the second echo image more suitable for the analysis on the ocean wave information while using the reception signal common to the formation of the first echo image. Regarding the process which the first echo image generation unit <NUM> as described herein, it is possible for the second echo image generation unit <NUM> to perform the same process.

Here, the second echo image generation unit <NUM> can generate the second echo image from the non-modulated signal only. In such case, the entire region forming the second echo image is formed by the non-modulated signal. Therefore, the wave analysis unit <NUM> can normally set the analysis region <NUM> irrelevant of the region formed from the pulse-compressed signal. Therefore, the wave analysis unit <NUM> can analyze the remote wave information in the range reflected by the echo. In addition, in such case, the pulse compression unit <NUM> can be configured to not output the pulse-compressed signal to the second echo image generation unit.

The solid-state radar device may also be provided on land as long as the configuration is satisfied.

The A/D conversion process described as a process in the transmission/reception unit <NUM> may be performed in any process. Therefore, the respective processes of the frequency filter unit <NUM> and the pulse compression unit <NUM> according to <FIG> may be performed by a central processing unit (CPU), and may also be processed by an analog circuit, which both are also referred to as processing circuitry.

The method for the process of the wave analysis is not particularly limited as long as the analysis result on the ocean wave information can be calculated from the echo image. For example, the wave analysis unit <NUM> may also acquire and analyze the relevance of the scan images consecutive in time or analyze the ocean wave information by calculating the cross spectra of these images and calculate the analysis result.

The specific configurations of the respective units are not limited to only the above embodiment, and various modifications are possible without departing from the gist of the disclosure.

The execution sequence of the respective processes of the operations, the procedures, the steps and the stages in the device, the system, the program, and the method described in the claims, the specification, and the drawings can be realized in any order, as long as the output of a prior process is used in a subsequent process. Regarding the flow in the claims, the specification, and the drawings, even though the terms such as "firstly", "secondly" are used for the ease of explanation, it does not mean that it is necessary to execute in such order.

Claim 1:
A solid-state radar device (<NUM>, <NUM>), comprising:
a transmission/reception unit (<NUM>) transmits and receives radio wave signals comprising a modulated signal and a non-modulated signal, which are pulse signals whose frequencies are different from each other;
a frequency filter unit (<NUM>) respectively separates the modulated signal and the non-modulated signal from the received radio wave signals based on the frequencies by using band pass filters;
a pulse compression unit (<NUM>) generate a pulse-compressed signal by pulse-compressing the modulated signal;
a first echo image generation unit (<NUM>) generates a first echo image based on the non-modulated signal and the pulse-compressed signal;
a wave analysis unit (<NUM>) analyzes ocean wave information based on one of the non-modulated signal and the pulse-compressed signal; and
a display signal generation unit (<NUM>) generates a display signal comprising the first echo image and/or the ocean wave information.