KR101916548B1 - Double polarization tranceiving apparatus and method for sweep radar broad scanning - Google Patents

Abstract

The present teachings relate to a dual polarization transmission and reception method using full polarization for wide scan of a sweep radar. More specifically, a plurality of feed horns are all turned on to transmit a beam to a wide area, and two horns are turned on to receive a signal when receiving. The received signal is separated into the vertical polarization and the horizontal polarization by the orthogonal mode polarization separator, and the signals are combined to remove the blind spot and scan the area to be observed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a double polarized transceiver for sweep radar wide area scanning, and a double polarized wave transmitting /

And more particularly to an apparatus and method for providing full-polarized wide-area beam transmission and dual-polarized reception for wide-area scanning of a sweep radar. BACKGROUND OF THE INVENTION Field of the Invention The present invention relates generally to satellite radar systems,

High Resolution Wide Swath (HRWS) and Sweep SAR methods are being studied for wide-area high-resolution observation systems.

The HRWS method uses a flat array method, and the Sweep SAR method uses a reflector and a feed horn. Comparing the two systems, it is known that the sweep SAR method can transmit relatively low power using a large reflector.

The average SAR system is very long in the operation of the satellite, so it transmits consecutively consecutive signals and continuously captures and stores echoes when receiving. That is, an echo signal arrives at the time of signal transmission and a blind range occurs. Therefore, it is necessary to adjust the Pulse Repeat Interval (PRI) or to increase the length of the antenna sufficiently to lengthen the transmission period of the broadcast signal. In the case of wide-area high-resolution observation, the pulse width of the pulse repetition frequency (PRF) should be lowered because the observation width is very wide. If the reflector length is short, lowering the pulse repetition frequency lowers the signal quality. Therefore, the pulse repetition frequency is increased. In such a case, a blind range is generated.

According to an embodiment of the present invention, an antenna unit for radiating a signal of multiple frequency bands, receiving a signal reflected from an observation area and transmitting the signal to a polarization selector, a first polarization selector for selecting a polarization of a reflected signal, And a switch module for controlling the on / off of the operation to select the polarization of the signal received by the first and second polarization selectors is disclosed .

According to another embodiment of the present invention, the antenna unit includes a plurality of feed horns for radiating a transmission signal of a corresponding band, and a reflector for reflecting signals radiated from the plurality of feed horns. The reflector may be circular or elliptical.

According to yet another embodiment, the first and second polarization selectors may comprise selecting vertical and / or horizontal polarizations of a transmitted signal and a received signal.

According to another embodiment, there is also provided a dual polarization transceiver further comprising an orthogonal mode polarization separator connected to the plurality of feed horns to separate vertical polarization and horizontal polarization.

The dual polarization transmission and reception method according to an exemplary embodiment of the present invention includes the steps of: radiating a signal of a multiple frequency band by an antenna unit; receiving a signal reflected by the antenna unit and transmitting the signal to a polarization selector; Selecting a polarization of the received signal, selecting a polarization of another received signal to which the second polarization selector reflects, and selecting a polarization of the signal that the switch module receives the first polarization selector and the second polarization selector And controlling on / off of the first and second polarized waves.

The step of radiating signals of multiple frequency bands by the antenna portion of the dual polarization transmission and reception method according to another embodiment includes the steps of a plurality of feed horns radiating a transmission signal of the corresponding band and a step in which the reflector radiates signals emitted from the plurality of feed horns And reflecting the reflected light. The reflector may include a circular or elliptical shape.

According to another embodiment, the step of selecting the polarization of the transmission / reception signal by the first polarization selector and the step of selecting the polarization of the transmission / reception signal by the second polarization selector may include selecting the vertical and / or horizontal polarization of the transmission signal and the reception signal And a step of transmitting and / or receiving signals.

According to another embodiment, the dual polarization transmitting / receiving method may be configured so that the orthogonal mode polarization separator is connected to the plurality of feed horns to separate the vertical polarization and the horizontal polarization.

According to one embodiment, a computer-readable recording medium storing a program for performing the above-described dual polarization transmission and reception method is disclosed.

1 is a flowchart of a dual polarization transmission / reception method according to an embodiment.
2 is a flowchart illustrating a method of analyzing a transmission signal according to an embodiment of the present invention.
3 shows a transmitting and receiving region according to an embodiment.
Figure 4 illustrates the problem of wide scan in accordance with one embodiment.
5 illustrates a method of solving a blind spot according to an embodiment.
6 shows a transmitting and receiving region of a dual polarization transmitting and receiving apparatus according to one embodiment.
FIG. 7 is a table showing the time-dependent polarization used in FIG.
8 is a structural diagram of a dual polarization transceiver according to an embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the rights is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

The terms used in the following description are chosen to be generic and universal in the art to which they are related, but other terms may exist depending on the development and / or change in technology, customs, preferences of the technician, and the like. Accordingly, the terminology used in the following description should not be construed as limiting the technical thought, but should be understood in the exemplary language used to describe the embodiments.

Also, in certain cases, there may be a term chosen arbitrarily by the applicant, in which case the meaning of the detailed description in the corresponding description section. Therefore, the term used in the following description should be understood based on the meaning of the term, not the name of a simple term, and the contents throughout the specification.

1 is a flowchart of a dual polarization transmission / reception method according to an embodiment. In order to transmit and receive double polarized waves, it is necessary to select the vertical / horizontal polarization of the transmitted and received signals and to analyze them. The signal 110 to be transmitted is formed (120) into a wide area. The shaped signal is reflected in the area to be observed and received 130 as a narrowband. The received signal is selected 140 by a polarization selector. The selected signals can be comprehensively analyzed (150) to provide high-resolution observations in wide areas.

When the transmission signal 110 is transmitted at one frequency, a blind range occurs because the distance between the observation area and the satellite is too long. The presence of this blind spot is well illustrated in FIG. Therefore, the transmission signal 110 uses two pulse repetition frequency (PRF) as a method for eliminating the blind spot. Each pulse repetition frequency (PRF) is configured to cancel the blind spots of the received signal in a complementary manner.

In the step of forming the wide area 120, a plurality of feed horns existing in the antenna unit are operated to radiate a beam to a wide area at a time. The signal emitted from the feed horn is reflected by the reflector and the beam is transmitted over a large area.

The step of receiving 130 in narrowband may include operating a portion of the feed horn in the antenna portion to receive a beam reflected in a narrow region. The beam reflected in the narrow area is reflected again on the reflector, enters the feed horn and receives the antenna.

The H / V polarization selection step 150 has the vertical and horizontal polarizations of each of the signals received in the narrowband according to the frequency of the transmitted signal 110.

2 is a flowchart illustrating a method of analyzing a transmission signal according to an embodiment of the present invention. Two frequency-domain signals are required to remove the blind spots of the transmission and reception signals. (210) a first frequency signal, and receives (220) a second frequency signal. (230) the area that can not be received by the dead zone in the frequency signal of each area, and thereafter comprehensively analyzes (240) the information of the receiving area of the two signals. The removal of the blind zone region of the signal and the specific interpretation are described in detail in Figs. 5 and 6. Fig.

3 shows a transmitting and receiving region according to an embodiment. A region 320 for forming a beam in a wide area by turning on all the feed horns in the antenna unit 310 of the radar, and an area 330 for receiving a part of the feed horns in a narrow region upon reception.

The anchor portion 310 is formed of a plurality of feed horns and a reflector. The plurality of feed horns can operate entirely or only partially depending on the point of time of transmission and reception of the signal. The signal emitted from the feed horn reflects off the reflector and spreads out over the wide area to be observed. The reflector may be circular or oval shaped so that the signal can be directed in a desired direction.

The area 320 for forming the beam in the wide area may be an earth surface or sea level. In other words, it means an area to be observed on the earth. Since the present teachings are for wide-area scanning of the sweep radar, the beams are formed in the widest possible area. When a beam is to be formed, it must be formed in a wide area, so that a plurality of feed horns existing in the antenna unit are turned on to perform forming.

The area 330 to be received by the narrowband is a part of the area that is formed into a wide area. And receives a part of the reflected area after the beam is formed in the wide area. You do not need to turn on all feed horns because you only receive a few areas at the time of reception, and you only need to operate two feed horns. When only one feed horn is operated, the blind range is generated according to the communication distance of the satellite and the earth, so that the signal can not be received perfectly. Therefore, a minimum of two feed horns must be operated, and in some cases, the present invention is not limited to this, and more than two feed horns may be operated to receive signals.

Figure 4 illustrates the problem of wide scan in accordance with one embodiment. A region 410 emitting a signal and a dead zone 420 are shown. According to one embodiment, when a signal is radiated in a specific frequency band, a signal at a portion where a blind zone overlaps with a radiated region of the signal becomes unreceivable, and this region becomes an unreceivable region 430 of the frequency. Therefore, only one frequency can not receive the signal completely, and for this reason two or more frequencies must be used. Therefore, each frequency should be configured to complement each other's blind spots.

The position of the region 410 that emits the signal may change according to the frequency, but a portion overlapping with the blind zone region 420 occurs at any position. The reason for the blind spot is not the frequency problem, but the transmission and reception at the same time, depending on the distance between the satellite radar and the earth.

The unreceivable region 430 has different positions depending on the frequency band of the signal. Accordingly, when the signals are synthesized by adjusting the frequency bands of two or more signals, it is possible to receive the information of the scanned region completely. The method of extinguishing a specific blind spot is discussed in detail in FIG.

5 illustrates a method of solving a blind spot according to an embodiment. Fig. 5 shows a blind spot, a transmission area and a reception enabled area. The blind spot is uniformly distributed in all frequency bands, and the area that does not overlap with the blind spot in the transmission area becomes the receivable area. Although two frequencies are used according to one embodiment, the present invention is not limited thereto and two or more frequencies may be used to remove the blind spot.

Let the transmission area on the left side of the two transmission areas be a transmission area on the first frequency and the transmission area on the right side be the transmission area on the second frequency. The remaining part is the receivable area of the first frequency except for the part where the transmission area of the first frequency overlaps with the blind spot. In the same manner, except for the portion where the transmission region of the second frequency overlaps the dead zone, the remaining portion becomes the receivable region of the second frequency. When the receivable region of the first frequency and the receivable region of the second frequency are combined, one receivable region which is intact is generated. Thus, combining the two received information in this way enables wide area scanning without blind spots.

6 shows a transmitting and receiving region of a dual polarization transmitting and receiving apparatus according to one embodiment. Let's look at the proposed system in more detail. Conventional quadrupole SARs transmit vertically polarized waves (V) and horizontally polarized waves (H) in one pulse repetition interval (PRI) to realize full polarization, and use one beam do. However, in the proposed system, two beams are generated and the vertical polarization (V) and the horizontal polarization (H) are simultaneously transmitted using the pulse repetition interval (PRI).

Tx. @ PRF1 shows the transmission area according to the first frequency, and Rx. @ PRF1 indicates a receivable area according to the first frequency. Likewise Tx. @ PRF2 shows the transmission region according to the second frequency, and Rx. And @ PRF2 indicates a receivable area according to the second frequency. (Rx. @ PRF1) of the first frequency except for the portion overlapping the dead zone among the transmission region (Tx. @ PRF1) of the first frequency. @ PRF2 of the second frequency except for a portion overlapping the dead zone of the transmission region Tx. @ PRF2 of the second frequency. The horizontal polarization and the vertical polarization according to time are shown in FIG.

FIG. 7 is a table showing the time-dependent polarization used in FIG. According to one embodiment, full polarization is realized by vertical polarization or horizontal polarization. At the time t0, transmission of the first frequency is transmitted with the horizontal polarization H, and reception of the first frequency simultaneously receives the horizontal polarization H and the vertical polarization V. At the time t0, on the contrary, the transmission of the second frequency is transmitted with the vertical polarization (V), and the reception of the second frequency simultaneously receives the vertical polarization (V) and the horizontal polarization (H).

At the time t1, it operates as a vertical polarization and a horizontal polarization opposite to the point of time t0. The transmission of the first frequency at t1 is transmitted with the vertical polarization (V), and the reception of the first frequency simultaneously receives the vertical polarization (V) and the horizontal polarization (H). At the time t1, the transmission of the second frequency is transmitted with the horizontal polarization H and the reception of the second frequency simultaneously receives the horizontal polarization H and the vertical polarization V.

8 is a structural diagram of a dual polarization transceiver according to an embodiment. The dual polarization transmitter / receiver of the present application has the following configuration. A switch 810 for adjusting the ON / OFF of the operation to select the polarization of the signal received by the polarization selector, a plurality Orthogonal mode polarization separator 840 and an antenna section. The antenna unit includes a plurality of feed horns 850 and a reflection plate 860.

The wideband forming process according to the configuration of the dual polarized wave transmitting / receiving device will be described. Transmitter 810 generates a signal for a wide scan. Since two signals with different frequencies are needed to remove the blind spot, there will be more than one transmitter. A signal output from each transmitter enters a switch module 830. All of the feed horns 850 are activated by the switch module 830 and the signal of the A transmitter and the signal of the B transmitter are emitted in all the feed horns 850. [ The signal emitted from the feed horn 850 is reflected by the reflection plate 860 and is radiated to an area to be scanned. In this manner, wide area forming is performed.

We will look at the process of receiving the wide-band-shaped narrowband after receiving the dual polarized wave transceiver. The wide-area forming and the narrow-area receiving are continuously performed simultaneously after the initial forming is performed. Therefore, a blind range occurs because transmission and reception are performed at the same time. In the narrowband reception process, a signal reflected from a part of the area to be scanned is reflected by the reflection plate 860 and transmitted to the feed horn 850. Upon receipt, the operation of the feed horn 850 is controlled by the switch module 830, and only the two feed horns operate to receive the signal. The signal received at the feed horn passes through the orthogonal mode polarization separator 840, the switch module 830, and is transmitted to the polarization selector 820. The orthogonal-mode polarization separator 840 separates the polarization of the received signal into vertically polarized waves or horizontally polarized waves. The signals separated into the vertically polarized wave or the horizontally polarized wave are transmitted to the polarization selector 820, and the polarization selector 820 selects a desired one of the separated signals and transmits the selected signal to the processor.

When operating the system in the above manner, a total of four feed horns are required since two signals (A, B) are transmitted and upon reception, the respective vertical and horizontal polarizations for the A and B signals are received . Each feed horn is divided into a vertical polarization (A / H) of A signal, a horizontal polarization (A / V) of A signal, a vertical polarization (B / H) of B signal, And receives the horizontal polarization (B / V). Therefore, it receives 4 channels in total.

Since a large area is transmitted and reception is performed simultaneously with transmission, a dead zone is generated. In order to remove a dead zone, the reflector of the antenna unit must be increased to about 13 m. However, there is a limit to the size of the payload that can be mounted on the satellite, and the smaller the reflector is, the more advantageous it is. In accordance with the present teachings, the analysis is performed by combining the two received signals by varying the pulse repetition frequency and scanning the region at different frequencies. Therefore, a large area can be scanned with a small antenna.

Meanwhile, the above-described dual polarization transceiver can be used in a sweep radar for wide-area scanning, and more specifically, it can be used in a satellite radar system for earth observation, a civilian ground radar system, and an environment monitoring radar. However, the present invention is not limited thereto, and a radar system for observing the ground can be used.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described with reference to the drawings, various modifications and variations may be made by those skilled in the art. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced. Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (11)

An antenna unit that emits a signal of a plurality of frequency bands using a plurality of beams, receives a signal reflected from the observation region, and transmits the signal to a polarization selector;
A first polarization selector for selecting a polarization of the received signal to be reflected;
A second polarization selector for selecting a polarization of another reflected signal; And
A switch module for controlling the on / off of the operation to select the polarization of the signal received by the first polarization selector and the second polarization selector
/ RTI >
The antenna unit includes:
When the vertical polarization is transmitted at the first frequency in the first pulse repetition interval, the horizontal polarization is transmitted at the second frequency, and when the horizontal polarization is transmitted at the first frequency at the second pulse repetition interval, A dual polarization transceiver for transmitting vertical polarization. The method according to claim 1,
Wherein the antenna unit comprises: a plurality of feed horns for radiating a transmission signal of a corresponding band; And
A reflector for reflecting a signal radiated from the plurality of feed horns;
And a second polarized wave transmitting / receiving unit. 3. The method of claim 2,
The first polarization selector and the second polarization selector,
Selecting the vertical and / or horizontal polarization of the received signal
And a second polarized wave transmitting / receiving unit. The method of claim 3,
An orthogonal mode polarization separator connected to the plurality of feed horns for separating vertical polarization and horizontal polarization,
And a second polarized wave transmitting / receiving unit. 5. The method of claim 4,
The reflector being circular or elliptical
And a second polarized wave transmitting / receiving unit. In the dual polarization transmission and reception method,
The antenna unit radiating signals in multiple frequency bands using a plurality of beams;
Receiving the signal reflected from the observation area of the antenna unit and transmitting the signal to the polarization selector;
Selecting a polarization of the received signal from which the first polarization selector reflects;
Selecting a polarization of another received signal to which the second polarization selector reflects; And
Adjusting the on / off operation of the switch module so as to select the polarization of the signal received by the first and second polarized wave selectors;
Lt; / RTI >
The step of radiating the signal comprises:
Transmitting a horizontal polarization at a second frequency when transmitting vertical polarization at a first frequency in a first pulse repetition interval; And
Transmitting a horizontal polarized wave at a first frequency in a second pulse repetition interval, transmitting a vertical polarized wave at a second frequency
/ RTI > The method according to claim 6,
The step of causing the antenna unit to radiate a signal in a multiple frequency band includes:
The plurality of feed horns emitting a transmission signal of the corresponding frequency band; And
Wherein the reflector reflects a signal radiated from the plurality of feed horns
/ RTI > 8. The method of claim 7,
The first polarization selector selecting the polarization of the transmission / reception signal and the second polarization selector selecting the polarization of the transmission / reception signal,
And selecting vertical and / or horizontal polarization of the transmission signal and the reception signal
/ RTI > 9. The method of claim 8,
Wherein the orthogonal mode polarization separator is connected to the plurality of feed horns to separate the vertical polarization and the horizontal polarization
/ RTI > The method of claim 1, further comprising: 10. The method of claim 9,
The reflector may be circular or elliptical
/ RTI > A computer-readable recording medium storing a program for performing the dual polarization transmitting / receiving method according to any one of claims 6 to 10.

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