Patent Publication Number: US-9854278-B2

Title: Antena arrangements and associated control methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2015-0066087 filed on May 12, 2015 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Field 
     Apparatuses and methods consistent with the exemplary embodiments relate to a broadcast receiving apparatus, which receives a radio frequency (RF) signal through an antenna and processes the RF signal to be displayed as an image, and a control method thereof, and more particularly to a broadcast receiving apparatus, which has an improved structure in quality of receiving an RF signal even though an circumstance where an antenna is set up is poor to receive the RF signal, and a control method thereof. 
     Description of the Related Art 
     An image processing apparatus processes a video signal or video data in accordance with various video processing processes. The image processing apparatus may display an image based on the processed video data on its own display panel, or output the processed video signal to another broadcast receiving apparatus provided with a panel so that on the corresponding broadcast receiving apparatus can display an image based on the processed video signal. That is, the image processing apparatus may include the panel capable of displaying an image or include no panel as long as it can process the video data. For example, the former may include a television (TV), and the latter may include a set-top box. Among these image processing apparatuses, an apparatus for receiving a broadcast signal from a transmitter of a broadcasting station and processing it to be displayed as a broadcast image will be called a broadcast receiving apparatus. The image processing apparatus is also called an image receiving apparatus in terms of receiving an image signal, and in particular called a broadcast receiving apparatus if it has a function of receiving a broadcast signal and displays a broadcast program. 
     The broadcast receiving apparatus or the image receiving apparatus may receive an image signal by a wired method or a wireless method. In contrast to the wired method of using a cable to receive an image signal, the wireless method involves the image receiving apparatus utilizing an antenna to receive an RF signal, i.e., an image signal. For example, the image receiving apparatus receives a broadcast signal from a transmitter of a broadcasting station through the antenna and processes the broadcast signal, thereby displaying a broadcast image. 
     In the image processing apparatus which receives the RF signal through the antenna, the antenna may be required to have high reception or accuracy in order to guarantee the quality of the displayed image. The easiest way to improve the reception of the RF signal by the antenna is to set up the antenna in a good location for receiving the RF signal. In other words, it is possible to improve the reception of the RF signal by setting up the antenna in an outdoor area where a signal strength is high. 
     However, not all antennas can be set up outdoors. In some cases, there may be no choice but to set up the antenna in an indoor area or the like where a signal strength is low. Although the antenna can be set up in the outdoor area, another antenna may have to be additionally set up in the indoor area in accordance with the characteristics of the RF signal. In this case, the reception of the antenna for receiving the RF signal is worsened by interference of a wall, a window or the like. Therefore, in order to guarantee the quality of the image processed by the image receiving apparatus when the antenna is set up where the signal strength is low, there is a need of a method of overcoming the foregoing limits to setup circumstances and improving the reception of the antenna for receiving the RF signal. 
     SUMMARY 
     According to an aspect of an exemplary embodiment, there is provided a broadcast receiving apparatus including: a plurality of unit antennas arranged at preset intervals, each unit antenna of the plurality of antennas being configured to receive a broadcast signal; a plurality of receiving modules, each receiving module of the plurality of receiving modules being configured to convert the broadcast signal received by a corresponding unit antenna of the plurality of unit antennas into a first signal and output the first signal; a filter configured to filter a noise component out of the first signals output by the plurality of receiving modules, synthesize the first signals into a second signal and output the second signal; and a signal processor configured to perform a signal process for displaying an image based on the second signal output from the filter. Thus, it is possible to filter a noise component out of the broadcast signals respectively received in the unit antennas, and it is possible to improve the quality of the broadcast signal for an image process. 
     A maximum distance between two unit antennas among the plurality of unit antennas may be shorter than a half wavelength of the broadcast signal. Thus, the correlation between the broadcast signal components of the broadcast signals respectively received in the plurality of unit antennas is raised, and the receiving sensitivity is improved in terms of the whole plurality of unit antennas. 
     The receiving module may convert the broadcast signal into the first signal by shifting the broadcast signal received in the unit antenna from a high frequency band into an intermediate frequency band. Here, the receiving module may include a radio frequency integrated circuit (RFIC). Thus, the frequency shift is performed by the oscillator in each receiving module, and thus the correlation between the noise components included in the first signals output from the respective receiving modules is lowered. Thus, it is possible for the filter to filter out the noise component. 
     The first signal may include a broadcast signal component and the noise component, and the filter may pass the broadcast signal components having relatively high correlation but remove the noise component having relatively low correlation by comparison between the first signals. Further, the filter may include an adaptive filter. Thus, the broadcast signal component is included while the noise component is excluded when the second signal is obtained from the first signals transmitted from the respective receiving modules. 
     The broadcast receiving apparatus may further include: a second antenna group including at least one unit antenna and spaced apart from a first antenna group including the plurality of unit antennas; and a signal synthesizer configured to synthesize second signals corresponding to the first antenna group and the second antenna group into a third signal and transmit the third signal to the signal processor. Here, a minimum distance between the first antenna group and the second antenna group may be longer than a half wavelength of the broadcast signal. Thus, both the antenna diversity and the receiving sensitivity are improved to thereby receive a broadcast signal with high definition. 
     The first antenna group may be installed at a location where a receiving electric field is weaker than that of a place for the second antenna group. Thus, although the two antenna groups are respectively installed outdoors and indoors, which are significantly different in terms of the receiving electric field strength, it is possible to receive the broadcast signal with high reception from the broadcast signals received in the two antenna groups. 
     According to an aspect of another exemplary embodiment, there is provided a broadcast receiving apparatus including: a single antenna configured to receive a broadcast signal; a plurality of receiving modules configured to convert the broadcast signal branched and output from the single antenna into first signals; a filter configured to filter a noise component out of the first signals received from the plurality of receiving modules and synthesize the first signals into a second signal, and output the second signal; and a signal processor configured to perform a signal process for displaying an image based on the second signal output from the filter. This, it is possible to filter the noise component out of the broadcast signal received in the single antenna, and it is possible to improve the quality of the broadcast signal for an image process. 
     According to an aspect of another exemplary embodiment, there is provided a method of controlling a broadcast receiving apparatus, the method including: receiving a broadcast signal through a plurality of unit antennas arranged at preset intervals; converting, by a plurality of receiving modules respectively corresponding to the plurality of unit antennas, the broadcast signal received in the plurality of unit antennas into first signals; filtering, by a filter, a noise component out of the first signals and synthesizing the first signals into a second signal; and displaying an image by processing the second signal output. Thus, it is possible to filter the noise component out of the broadcast signals respectively received in the unit antennas, and it is possible to improve the quality of the broadcast signal for an image process. 
     A maximum distance between two unit antennas among the plurality of unit antennas is shorter than a half wavelength of the broadcast signal. Thus, the correlation between the broadcast signal components of the broadcast signals respectively received in the plurality of unit antennas is raised, and the receiving sensitivity is improved in terms of the whole plurality of unit antennas. 
     The converting the broadcast signals into the first signals respectively may include converting the broadcast signal into the first signal by shifting the broadcast signal received in the unit antenna from a high frequency band into an intermediate frequency band. Here, the receiving module may include a radio frequency integrated circuit (RFIC). Thus, the frequency shift is performed by the oscillator in each receiving module, and thus the correlation between the noise components included in the first signals output from the respective receiving modules is lowered. Thus, it is possible for the filter to filter out the noise component. 
     The first signal may include a broadcast signal component and the noise component, and the synthesizing the first signals into the second signal may include acquiring the broadcast signal components having relatively high correlation but removing the noise component having relatively low correlation by comparison between the first signals. Further, the filter may include an adaptive filter. Thus, the broadcast signal component is included excluding the noise component when the second signal is obtained from the first signals transmitted from the respective receiving modules. 
     A second antenna group may include at least one unit antenna and be spaced apart from a first antenna group including the plurality of unit antennas, wherein displaying the image includes displaying an image based on a third signal obtained by synthesizing the second signals respectively output from the first antenna group and the second antenna group. Here, a minimum distance between the first antenna group and the second antenna group may be longer than a half wavelength of the broadcast signal. Thus, both the antenna diversity and the receiving sensitivity are improved to thereby receive a broadcast signal with high definition. 
     The first antenna group may be installed at a place where a receiving electric field is weaker than that of a place for the second antenna group. Thus, although the antenna groups are respectively installed outdoors and indoors, which are significantly different in the receiving electric field strength from each other, it is possible to acquire the broadcast signal with high reception from the broadcast signals received in the two antenna groups. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects will become apparent and more readily appreciated from the following description of exemplary embodiments, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates an antenna set up in an image receiving apparatus according to a first exemplary embodiment; 
         FIG. 2  illustrates an antenna set up in an image receiving apparatus according to a second exemplary embodiment; 
         FIG. 3  illustrates an antenna set up in an image receiving apparatus according to a third exemplary embodiment; 
         FIG. 4  illustrates an antenna set up in an image receiving apparatus according to a fourth exemplary embodiment; 
         FIG. 5  is a block diagram of the image receiving apparatus of  FIG. 4 ; 
         FIG. 6  is a block diagram of a signal processor in the image receiving apparatus of  FIG. 4 ; 
         FIG. 7  is a block diagram of a signal synthesizer in the signal processor of  FIG. 6 ; 
         FIG. 8  is a flowchart of a signal process in the image receiving apparatus of  FIG. 4 ; 
         FIG. 9  is a block diagram of an image receiving apparatus according to a fifth exemplary embodiment; 
         FIG. 10  is a flowchart of a signal process in the image receiving apparatus of  FIG. 9 ; 
         FIG. 11  is a block diagram of an image receiving apparatus according to a sixth exemplary embodiment; 
         FIG. 12  is a flowchart of a signal process in the image receiving apparatus of  FIG. 11 ; 
         FIG. 13  is a block diagram of an image receiving apparatus according to a seventh exemplary embodiment; 
         FIG. 14  is a flowchart of a signal process in the image receiving apparatus of  FIG. 13 ; 
         FIG. 15  is a block diagram of an image receiving apparatus according to an eighth exemplary embodiment; 
         FIG. 16  is a flowchart of a signal process in the image receiving apparatus of  FIG. 15 ; 
         FIG. 17  illustrates a user interface (UI) to be displayed on an image receiving apparatus according to a ninth exemplary embodiment; 
         FIG. 18  is a block diagram of the image receiving apparatus of  FIG. 17 ; 
         FIG. 19  illustrates a system according to a tenth exemplary embodiment; and 
         FIG. 20  is a block diagram of an access point (AP) in the System of  FIG. 19 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Below, exemplary embodiments will be described in detail with reference to accompanying drawings. The following descriptions of the exemplary embodiments are made by referring to elements shown in the accompanying drawings, in which like numerals refer to like elements having substantively the same functions. 
     In the description of the exemplary embodiments, an ordinal number used in terms such as a first element, a second element, etc. is employed for describing variety of elements, and the terms are used for distinguishing between one element and another element. Therefore, the meanings of the elements are not limited by the terms, and the terms are also used just for explaining the corresponding embodiment without limiting the idea of the invention. 
     Further, the exemplary embodiments will describe only elements directly related to the idea of the invention, and description of the other elements will be omitted. However, it will be appreciated that the elements, the descriptions of which are omitted, are not unnecessary to realize the apparatus or system according to the exemplary embodiments. In the following descriptions, terms such as “include” or “have” refer to presence of features, numbers, steps, operations, elements or combination thereof, and do not exclude presence or addition of one or more other features, numbers, steps, operations, elements or combination thereof. 
       FIG. 1  illustrates an antenna  110  set up in an image receiving apparatus  100  according to a first exemplary embodiment; 
     As shown in  FIG. 1 , the image receiving apparatus  100  according to this exemplary embodiment wirelessly receives an image signal from a transmitter  10  of a broadcasting station and the like. In this exemplary, the image signal is a radio frequency (RF) signal, e.g., a broadcast signal transmitted from the transmitter  10 . However, the present inventive concept is not limited to this case where a sender is the transmitter  10  and the image signal is the broadcast signal. Alternatively, the present inventive concept may be broadly applied to a case where various transmitting apparatuses transmit image signals in the form of RF signals. 
     The image receiving apparatus  100  may be achieved variously. For example, the image receiving apparatus  100  may be a television (TV) that displays a broadcast image, or a set-top box that outputs a processed broadcast signal to an external display apparatus so that the external display apparatus can display a broadcast image. Alternatively, the image receiving apparatus  100  may be a relay that relays a broadcast signal to another apparatus. 
     The image receiving apparatus  100  may use various methods to receive a broadcast signal. In this embodiment, the image receiving apparatus  100  wirelessly receives a broadcast signal through a radio frequency (RF) antenna  110 . The image receiving apparatus  100  is tuned to a broadcast signal received through the antenna  110 , converts the broadcast signal into a digital signal, and shifts it to a baseband to undergo demultiplexing and decoding, thereby processing a broadcast image to be displayed. 
     The antenna  110  is a kind of converter for transmitting or receiving an electromagnetic wave of a certain frequency band, in which an electromagnetic wave of a radio frequency (RF) band is converted into an electric signal or the electric signal is converted in to the electromagnetic wave. The antenna  110  is an array of electric conductors that emits an electromagnetic field generated when a certain voltage is applied together with modified electric current. Therefore, the transmitting/receiving performance of the antenna  110  is closely related with an electric field of an circumstance where the antennal  110  is installed. 
     The quality of a broadcast image displayed by the image receiving apparatus  100  depends on many parameters. Among them, a particularly important parameter in the case of a terrestrial broadcast is the reception of the broadcast signal. To improve the reception of the broadcast signal, the antenna  110  has to be installed in an circumstance where a receiving electric field is high. Therefore, the antenna  110  is usually installed at a rooftop or the like outside where there is little interference with other building structures. 
     Additionally, in accordance with circumstances where the image receiving apparatus  100  and the antenna  110  are installed, it may be difficult to install the antenna  110  outdoors, or it may be difficult to connect a lead wire of the antenna  110  to the image receiving apparatus  100  installed indoors even though the antenna  110  is installed outdoors. In these cases, the antenna  110  is installed indoors. 
       FIG. 2  illustrates an antenna  120  set up in an image receiving apparatus  100  according to a second exemplary embodiment. 
     As shown in  FIG. 2 , the image receiving apparatus  100  connects with the antenna  120  installed indoors. The antenna  120  receives a broadcast signal from the transmitter  10  and transmits it to the image receiving apparatus  100 . 
     By the way, the broadcast signal from the transmitter  10  is interfered with a wall, a window or the like structure until reaching the antenna  120 . Since an indoor receiving electric field is lower than an outdoor receiving electric field by not less than 10 dB, the reception of the indoor antenna  120  is significantly lower than that of the outdoor antenna. In result, a broadcast image displayed by processing the broadcast signal received in the indoor antenna  120  has a low quality. 
     For this reason, an active antenna may be used as the indoor antenna  120 . The active antenna is an antenna for a small television (TV) and is focused on directionality. The active antenna is designed placing emphasis on directionality rather than efficiency with respect to noise in case of a city or the like region where an electric field is relatively strong. Thus, the active antenna is achieved by an antenna that includes a built-in low noise amplifier to have a minimum value within an allowable range of a signal to noise ratio (SNR). The active antenna is manufactured by combining a loop antenna having a directional gain of about 3 dB with an active device such as a transistor, a tunnel diode, a varactor, etc. 
     Although the active antenna is used as the indoor antenna  120 , a noise figure of a preamplifier is currently limited to 4 dB to 5 dB. Therefore, to improve the reception of the indoor antenna  120  up to that of the outdoor antenna  110  (refer to  FIG. 1 ), a plurality of antennas  120  may be installed inside of a building. 
       FIG. 3  illustrates an antenna  130  set up in an image receiving apparatus  200  according to a third exemplary embodiment. 
     As shown in  FIG. 3 , the image receiving apparatus  200  includes a plurality of antennas  130  to receive an RF signal. The image receiving apparatus  200  includes an antenna combining section  210  to process RF signals respectively received from the plurality of antennas  130 , and outputs the RF signal of high reception. 
     Multiple-input multiple-output (MIMO) is a smart antenna technology that uses a plurality of antennas to increase the capacity of wireless communications. MIMO uses a plurality of antennas for each of a transmitter and a receiver, and increases the capacity in proportion to the number of used antennas. For example, if M antennas are installed at the receiver and N antennas are installed at the transmitter, an average transmission capacity is generally increased as much as min(N, M). In the case of M=1 and the plurality of antennas used for only the transmitter, it will be called multiple-input single-output (MISO). In the case of N=1 and the plurality of antennas used for only the receiver, it will be called single-input multiple-output (SIMO). In the case of (N, M)=(1, 1), it will be called single-input single-output (SISO). According to this exemplary embodiment, the plurality of antennas  130  are used for the receiver like the MIMO and SIMO technologies. 
     The reason why the MIMO technology is used is because an antenna diversity effect and a spatial multiplexing effect are maximized. Below, concepts of the diversity and the spatial multiplexing will be described in brief. 
     The diversity method is utilized for lessening effects from fading occurrence such as irregular change in the receiving electric field under RF circumstances. Since copies of a signal differently transmitted in time, frequency and space domains are different from one another, the diversity method synthesizes them to lessen the fading effects and then receives and processes the signal. The diversity method includes a space diversity method, a polarization diversity method, a frequency diversity method, and a time diversity method. 
     The fading refers to the fact that an amplitude, a phase and the like of a signal are irregularly changed as two or more electromagnetic waves different in path interfere with each other. The interference includes constructive interference and destructive interference. 
     In the case of the space diversity, two or more antennas which are spatially separated and respectively installed at positions with the minimum fading correlation, and the best signal is selectively, thereby lessening the fading effects. The antenna diversity method includes space diversity method. 
     The meaning of the correlation is as follows. If there is a relationship, intensity of the relationship, directionality of relationship, dependency or the like between two factors such as signals, functions, random variables, phenomena, etc., it will be called correlation or similarity between these two factors. The correlation may be expressed and measured by a scatter diagram, covariance, a correlation coefficient, a correlation function, etc. The scatter diagram shows how widely observed data are scattered from the center, and represents the correlation in the form of a geometrical figure. The covariance is a yardstick of the correlation about a direction and degree of linear dependency between variables. The correlation coefficient is a normalized yardstick of correlation evaluation, and is a standard for evaluating reliance and dependence between two random variables. That is, the correlation coefficient is a criterion normalized for quantitative comparison in correlation between two variables. 
     The polarization diversity method lessens the fading effects by individually transmitting two polarizations, a vertical polarization and a horizontal polarization, based on a principle that the fading is varied depending on the polarizations. 
     The frequency diversity method is based on a principle that a fading correlation is decreased as a frequency interval between two or more frequencies becomes larger since different frequencies make a change in a fading effect of the receiving electric field. 
     The time diversity method is achieved by repetitively sending the same information leaving a time lag. 
     The spatial multiplexing is a method in which multiple spatially separated channels in not a time or frequency domain but a space domain are transmitted by one logical channel, and thus a plurality of information streams are separated into a plurality of spatial streams and transmitted through a plurality of antennas. In the spatial multiplexing, a signal having a large amount of information is divided into many spatial streams and then transmitted at once, and different individual signals are transmitted through many spatial paths at once. Thus, it is possible to increase channel capacity without enlarging a frequency bandwidth and raising transmission power. 
     According to this exemplary embodiment, the following structure is used to heighten the effects of the antenna diversity. 
     The plurality of antennas  130  are installed in such a manner that a distance d 1  between the respective antennas  130  is equal to or longer than λ/2. Here, λ is a wavelength of a received RF signal. If d 1  is set like this, the RF signals respectively received in the antennas  130  are different in phase change from one another and thus have a low correlation therebetween. This means that the respective signals are independent of one another in terms of multiple-path fading. The multiple-path fading is a phenomenon that electromagnetic waves received along different paths are reflected from many objects and thus irregularly fluctuate due to interference between their different amplitudes, phases, incident angles, polarizations, etc. 
     If the signals are independent of one another, one signal is less likely to undergo deep fading even though another signal experiences deep fading. Therefore, it is possible to get a signal with less multi-path fading by combining two independent signals. This is a method of increasing transmission reliability by a diversity gain. Based on this method, the antenna combining section  210  processes the RF signals respectively received from the antennas  130  to thereby get a RF signal of high quality. 
     According to an exemplary embodiment, the distances between the plurality of antennas  130  are equal to or longer than λ/2, and thus the effect of the antenna diversity is improved, thereby resulting in getting a signal with less fading. 
     However, if the respective antennas  130  have to be spaced apart by a distance not shorter than λ/2, the plurality of antennas  130  occupies much space. Although the plurality of antennas  130  are installed, it is not easy to improve the effect of the antenna diversity to such an extent as to get a signal with less fading approximate to that of a signal received in the external antenna. 
     Further, the method according to this exemplary embodiment makes the distance between the antennas  130  be longer as a frequency becomes lower, and therefore the antenna diversity gain may be decreased. 
     Similar to the signal reception being raised by lessening the fading when the antennas  130  are installed indoors, there is a need of raising the signal reception up to that of the outdoor antenna even when the antennas  130  respectively installed both indoors and outdoors are combined. If the signal reception of the indoor antenna  130  is significantly different from that of the outdoor antenna, for example, or if the signal reception of the indoor antenna  130  is much lower than that of the outdoor antenna, it is not easy to synthesize two signals respectively received from the indoor and outdoor antennas. 
     To minimize this problem, a fourth exemplary embodiment will be described below. 
       FIG. 4  illustrates an antenna  140  set up in an image receiving apparatus  300  according to the fourth exemplary embodiment. 
     As shown in  FIG. 4 , the image receiving apparatus  300  according to the fourth exemplary embodiment includes a plurality of antennas  140  to receive an RF signal. Similarly to the third exemplary embodiment, the plurality of antennas  140  is installed indoors or the like circumstances where the receiving electric field is low. However, in contrast to the third exemplary embodiment, two antennas  140  farthest away from each other among the plurality of antennas  140  are installed so that a distance d 2  between them can be shorter than λ/2. Here, λ is a wavelength of the received RF signal. In other words, the plurality of antennas  140  are installed within a circle having the diameter d 2  shorter than λ/2. 
     It will be naturally appreciated that the effect of the antenna diversity is drastically decreased when the plurality of antennas  140  is arranged within the foregoing circle. The distance d 1  longer than λ/2 (see  FIG. 3 ) in the third exemplary embodiment is to raise the reliability of the synthesized signal by lowering the correlation and increasing the independency between the signals received in the respective antennas and thus securing the diversity gain. 
     However, if all the antennas  140  are placed within a range of λ/2 according to this exemplary embodiment, the correlation increases but the degree of independence is lowered between the signals received in the respective antennas  140 . In this case, if a signal received in one antenna  140  experiences the deep fading, signals received in the other antenna  140  are also likely to experience the deep fading. In this case, even if the signals respectively received in the plurality of antennas  140  are synthesized, the synthesized signal is likely to be characterized by deep fading. In such a case where the plurality of antennas  140  is densely arranged, it is difficult to achieve the antenna diversity effect. In this exemplary embodiment, a hardware structure is added to the image receiving apparatus  300  in order to raise the receiving sensitivity of the RF signal, and details will be described later. 
     Below, the image receiving apparatus  300  will be described with reference to  FIG. 5 . 
       FIG. 5  is a block diagram of the image receiving apparatus  300   
     As shown in  FIG. 5 , the image receiving apparatus  300  according to this exemplary embodiment is a TV capable of receiving, processing and displaying a broadcast signal by itself. However, the present inventive concept is applicable to any devices that can receive the RF signal, and thus the image receiving apparatus  300  may be achieved by an image processing apparatus that cannot display an image by itself like a set-top box or by a relay that receives a broadcast signal and delivers it to another device. Further, the antenna  140  connected to the image receiving apparatus  300  is not a single antenna but a multiple antenna including a plurality of antennas. 
     The image receiving apparatus  300  includes a signal receiver  310  that receives a RF broadcast signal received in the antenna  140 , a display  320  that displays an image based on the broadcast signal received in the signal receiver  310 , a user input  330  that receives a user&#39;s input, a storage  340  that stores data/information, and a signal processor  350  that controls general operations of the image receiving apparatus  300  and processes data. 
     The signal receiver  310  receives a broadcast signal through the antenna  140  and transmits it to the signal processor  350 . The signal receiver  310  may be tuned to a certain channel for receiving the broadcast signal and transmit the received broadcast signal to the signal processor  350 . The signal receiver  310  is not limited to receiving the broadcast signal through the antenna  140 , and may interactively communicate with the exterior. The signal receiver  310  may be achieved by an assembly of connection ports or connection modules corresponding to communication standards, and its supportable protocols and communication targets are not limited to one kind or type. For example, the signal receiver  110  may include a Wi-Fi communication module for wireless communication, an Ethernet module for wired communication, and a universal serial bus (USB) port for local connection with a USB memory or the like as well as the antenna  140  for receiving an RF signal. 
     The display  320  displays an image based on an image signal processed by the signal processor  350 . For example, the display  320  displays a broadcast image based on the tuned broadcast signal output from the signal processor  350 . There are no limits to the types of the display  320 . For example, the display  120  may be achieved by various display types such as liquid crystal, plasma, a light-emitting diode, an organic light-emitting diode, a surface-conduction electron emitter, a carbon nano-tube, nano-crystal, etc. 
     The display  320  may include additional elements in accordance with the types of the panel. For example, if the display  320  is achieved by the liquid crystal, the display  130  includes a liquid crystal display (LCD) panel, a backlight unit for supplying light to the LCD panel, and a panel driving substrate for driving the LCD panel. 
     The user input  330  transmits various preset control commands or information to the signal processor  350  in accordance with a user&#39;s control or input. The user input  330  transmits signals corresponding to various events, which occur by a user&#39;s control in accordance with a user&#39;s intention, to the signal processor  350 . The input unit  330  may be variously achieved in accordance with information input methods. For example, the input unit  330  may include a key/button provided on an outer side of the image receiving apparatus  300 , an additional remote controller separated from the image receiving apparatus  300 , a touch screen formed integrally with the display  320 , etc. 
     The storage  340  stores various pieces of data under process and control of the signal processor  350 . The storage  340  is accessed by the signal processor  350  and performs reading, writing, editing, deleting, updating or the like with regard to data. The storage  340  is achieved by a flash-memory, a hard-disc drive or the like nonvolatile memory to preserve data regardless of supply of system power in the image receiving apparatus  300 . 
     The signal processor  350  performs various processes with regard to data or signals received in the signal receiver  310 . When the broadcast signal is received in the signal receiver  310 , the signal processor  350  applies a video processing process to the tuned broadcast signal, and outputs the processed broadcast signal to the display  320 , thereby displaying an image on the display  320 . 
     There are no limits to the kind of image processing process performed by the signal processor  160 , and the video processing process may for example include demultiplexing for separating a stream into sub streams such as a video signal, an audio signal and additional data, decoding corresponding to video formats of an image stream, de-interlacing for converting an image stream from an interlaced type into a progressive type, scaling for adjusting an image stream to have a preset resolution, noise reduction for improving image quality, detail enhancement, frame refresh rate conversion, etc. 
     Since the signal processor  350  can perform various processes in accordance with the kinds and characteristics of signal or data, the process performable by the signal processor  350  is not limited to the video processing process. Further, data that can be processed by the signal processor  350  is not limited to only data received in the signal receiver  310 . For example, if a user&#39;s voice is input to the image receiving apparatus  300 , the signal processor  350  may process the voice in accordance with a preset voice recognition processing process. The signal processor  350  is achieved by a system-on-chip (SOC), in which many functions are integrated, or an image processing board where individual chip-sets for independently performing the processes are mounted to a printed circuit board. 
     The signal processor  350  may perform control so that a broadcast signal corresponding to a frequency of a certain channel can be received and displayed as a broadcast image. If the user input  330  receives a command for selecting a certain channel while the signal receiver  310  receives the broadcast signal, the signal processor  350  acquires a tuning frequency of the selected channel. Then, the signal processor  350  performs control to process the broadcast signal corresponding to the selected frequency and display a broadcast image based on the processed broadcast signal through the display  320 . 
     Below, details of the signal processor  350  will be described with reference to  FIG. 6 . 
       FIG. 6  is a block diagram of the signal processor  350 .  FIG. 6  shows only basic elements of the signal processor  350 , and an actual product of the signal processor  350  includes additional elements besides the elements described below. 
     As shown in  FIG. 6 , the signal receiver  310  includes a tuner  311  to be tuned to a certain frequency to receive a broadcast signal. Further, the signal processor  350  includes a signal synthesizer  351  for synthesizing broadcast signals received from the tuner  311  of the signal receiver  310  and respectively corresponding to the antennas  140 , a demultiplexer  353  for dividing the synthesized signal from the signal synthesizer  351  into a plurality of sub signals, a decoder  355  for decoding the sub signals output from the demultiplexer  353 , a scaler  357  for scaling a video signal among the decoded sub signals and outputting it to the display  320 , and a central processing unit (CPU)  359  for performing calculation and control for the operations of the signal processor  350 . 
     Referring to  FIG. 6 , the signal synthesizer  351  belongs to the signal processor  350 , but this is given only for the illustrative purposes. Alternatively, the signal synthesizer  351  may belong to the signal receiver  310  as long as the signal synthesizer  351  serves to synthesize signals respectively received in the antenna  140  and get a broadcast signal with improved reception quality. Details of the signal synthesizer  351  will be described later. 
     When a broadcast signal is received in the antenna  140 , the tuner  311  is tuned to a frequency of a designated channel to receive a broadcast signal and converts the broadcast signal into a transport stream. The tuner  311  converts a high frequency of a carrier wave received via the antenna  140  into an intermediate frequency band and converts it into a digital signal, thereby generating a transport stream. To this end, the tuner  311  has an analog/digital (A/D) converter. Alternatively, the A/D converter may be designed to be included in not the tuner  311  but a demodulator. 
     The demultiplexer  353  performs a reverse operation of the multiplexer. That is, the demultiplexer  353  connects one input terminal with a plurality of output terminals, and distributes a stream input to the input terminal to the respective output terminals in accordance with selection signals. For example, if there are four output terminals with respect to one input terminal, the demultiplexer  353  may select each of the four output terminals by combination of selection signals having two level of 0 and 1. 
     In the case where the demultiplexer  353  is applied to the image receiving apparatus  300 , the demultiplexer  353  divides the transport stream received from the tuner  311  into the sub signals of a video stream, an audio stream and an additional data stream and outputs them to the respective output terminals. 
     The demultiplexer  353  may use various methods to divide the transport stream into the sub signals. For example, the demultiplexer  353  divides the transport stream into the sub signals in accordance with packet identifiers (PID) given to packets in the transport stream. The sub signals in the transport stream are independently compressed and packetized according to channels, and the same PID is given to the packets corresponding to one channel so as to be distinguished from the packets corresponding to another channel. The demultiplexer  353  classifies the packets in the transport stream according to the PID, and extracts the sub signals having the same PID. 
     The decoder  355  decodes each of the sub signals output from the demultiplexer  353 . In this exemplary embodiment, one decoder  355  is illustrated, but not limited thereto. Alternatively, a plurality of decoders  355  may be provided to decode the sub signals respectively. That is, the decoder  355  may include a video decoder for decoding a video signal, an audio decoder for decoding an audio signal, and a data decoder for decoding additional data. 
     Since the sub signals transmitted to the decoder  355  are encoded by a certain format, the decoder  355  performs a decoding process to return the sub signal to a state before an encoding process by performing an opposite process to the encoding process with regard to the sub signal. Therefore, if the sub signal output from the demultiplexer  353  is not encoded, i.e. not compressed, this sub signal is transmitted to the scaler  357  without undergoing the process of the decoder  355  or is transmitted to the scaler  357  by bypassing the decoder  355 . 
     The scaler  357  scales the decoded video signal in accordance with the resolution of the display  320  or a separately designated resolution. After the scaling process, the video signal is displayed on the display  320 . 
     The CPU  359  is an element for performing central calculation to operate general elements in the signal processor  350 , and plays a central role in parsing and calculating data. The CPU  359  internally includes a processor register in which commands to be processed are stored; an arithmetic logic unit (ALU) being in charge of comparison, determination and calculation; a control unit for internally controlling the CPU  359  to analyze and carry out the commands; an internal bus, a cache, etc. Further, the CPU  359  externally involves a random access memory (RAM) to which data to be processed is loaded. 
     With this structure, the signal processor  350  makes a synthesized signal by synthesizing the signals respectively received from the plurality of antennas  140 , and processes the synthesized signal to be displayed as a broadcast signal on the display  320 . 
     Below, the signal synthesizer will be described with reference to  FIG. 7 . 
       FIG. 7  is a block diagram of the signal synthesizer. 
     As shown in  FIG. 7 , an image receiving apparatus  400  includes a plurality of antennas  410 , a plurality of radio frequency integrated circuits (RFICs)  420  for individually receiving a broadcast signal through the respective antennas  410 , a plurality of analog-digital converters (ADC)  430  for converting the signals output from the respective RFICs  420  into digital signals, and an adaptive filter  440  for synthesizing the signals output from the plurality of ADCs  430 . 
     The image receiving apparatus  400  shown in  FIG. 7  is the same as the image receiving apparatus  300  of  FIG. 5  and  FIG. 6 , the tuner  311  (see  FIG. 6 ) includes the RFIC  420 , and the signal synthesizer  351  (see  FIG. 6 ) includes the ADC  430  and the adaptive filter  440 .  FIG. 7  illustrates that the ADC  430  belongs to the signal synthesizer  351  (see  FIG. 6 ), but is not limited thereto. Alternatively, the ADC  430  may belong to the signal receiver  310  (see  FIG. 6 ) or the tuner  311  (see  FIG. 6 ). 
     As described above with reference to  FIG. 4 , the plurality of antennas  410  are installed so that the distance d 2  between the two antennas  410  farthest away from each other can be shorter than λ/2. The broadcast signals respectively received in the antennas  410  are transmitted to the RFICs  420  of the antennas  410 . 
     The RFIC  420  is provided in each of the antennas  410  and shifts the broadcast signal received in the antenna  410  from a high frequency band into an intermediate frequency band. If the number of antennas  410  is M, the number of RFIC  420  is also M. The reason why the number of RFICs  420  is equal to the number of antennas  410  will be described later. To shift a frequency, the RFIC  420  includes an oscillator. 
     The RF approximately ranges from 300 MHz to 30 GHz. In a field of electronic technology, the RFIC  420  generally refers to an integrated circuit designed for wireless communication. The integrated circuit (IC) is a circuit that includes many transistors and various passive components, such as resistors, capacitors and the like, that are integrated together on a semiconductor substrate. The IC may be classified into a small scale IC (SSI), a medium scale IC (MSI), a large scale IC (LSI), etc. in accordance with the number of gates. The RFIC  420  is based on functional classification, and is an IC for receiving an RF signal. 
     The ADC  430  is an electronic circuit that converts an analog electric signal into a digital electric signal. Since it is harder to store and process an analog signal than a digital signal, the analog signal is converted by the ADC  430  into the digital signal. In general, it is advantageous in terms of noise if an analog signal is converted into a digital signal, but the signal may be distorted during the conversion. 
     In contrast to the ADC  430 , the DAC  450  is an electronic circuit for converting a digital electric signal into an analog electric signal. The DAC  450  performs an opposite process to the process of the ADC  430 . 
     The plurality of RFICs  420  may use the same clocks, but not limited thereto. Alternatively, the plurality of RFICs  420  may use different clocks within an allowable error. Likewise, the plurality of ADC  430  may use the same clocks or may use different clocks within an allowable error. In this exemplary embodiment, a signal input to the ADC  430  has an intermediate frequency, but not limited thereto. Alternatively, the signal input to the ADC  430  may have a high frequency band or a baseband. 
     The adaptive filter  440  is a linear filter having a transmission function to be controlled by variable parameters and adjusts the parameters in accordance with an optimization algorithm. Due to complexities of the optimization algorithm, the adaptive filter  440  is usually a digital filter. Therefore, the ADC  430  is provided at the front end of the adaptive filter  440 . Since some parameters for a required process are not previously known or varied, the adaptive filter  440  is required in some applications or circuits. The closed loop of the adaptive filter employs a feedback in the form of an error signal so as to optimize its transmission function. The closed loop of the adaptive filter includes use of a cost function as a yardstick for an optimum performance of a filter, and thus determines how the transmission function of the filter is adjusted in order to minimize costs at the next turn. 
     In this exemplary embodiment, the adaptive filter  440  synthesizes input signals received from the respective ADCs  430  and outputs a synthesized signal. During the synthesizing process, the adaptive filter  440  gives weights to respective input signals and then adds them up. Through this process, noise is drastically removed from a result of synthesizing the input signals, and therefore a signal synthesized by and output from the adaptive filter  440  becomes a signal with excellent reception approximate to the quality of a broadcast signal first transmitted from the transmitter. 
     Such a result in the signal of the adaptive filter  440  is closely related with the installation structures of the antenna  410  and the RFIC  420 , and these structures will be described below. 
     According to the third exemplary embodiment (see  FIG. 3 ), two adjacent antennas among the plurality of antennas  130  (see  FIG. 3 ) are spaced apart from each other at a distance not shorter than a half wavelength of a received signal to thereby raise the effect of the antenna diversity when the received signals are synthesized. 
     On the other hand, according to this exemplary embodiment, a distance between two antennas farthest away from each other among the plurality of antennas  410  is shorter than the half wavelength of the received signal. In this case, the effect of the antenna diversity is not highly expected on the contrary to that of the third exemplary embodiment. Nevertheless, this exemplary embodiment results in the receiving sensitivity higher than that of only one antenna since the plurality of antennas  410  are densely arranged. 
     According to the third exemplary embodiment, a signal received in a certain antenna  130  (see  FIG. 3 ) has low correlation with a signal received in another antenna  130  (see  FIG. 3 ). On the other hand, according to the exemplary embodiment of  FIG. 7 , a signal received in a certain antenna  410  has high correlation with a signal received in another antenna  410 . However, in such a case where the plurality of antennas  410  are densely arranged within a narrow area according to this exemplary embodiment, if a certain received signal has high noise, the other signals are likely to have high noise. Therefore, it is difficult to remove noise from the synthesized signal of the received signals. 
     Thus, according to this exemplary embodiment, the RFICs  420  are respectively provided in the antennas  410 , so that the signals respectively received in the antenna  410  can be shifted from a high frequency band into an intermediate frequency band through individual shift processes. Additionally, the frequency shift process of the RFIC  420  needs an oscillating operation of an oscillator, and thus each RFIC  420  includes an individual oscillator. 
     In such a structure of the image receiving apparatus  400  according to an exemplary embodiment, noise may be added to a broadcast signal as follows: noise may be transmitted from the transmitter to the antenna  410 , or noise may be added while the broadcast signal is processed in the image receiving apparatus  400  after being received in the antenna  410 . Between the two cases, the latter more significantly causes the noise. Referring to the processes according to this exemplary embodiment, the noise is significantly added to the signal during the frequency shift process of the RFIC  420 , and this noise is caused by the oscillating operation of the oscillator provided in the RFIC  420 . 
     According to this exemplary embodiment, since the plurality of antennas  410  are densely arranged within a narrow area, it is expected that the signals respectively received in the plurality of antennas  410  have high correlations therebetween. If the image receiving apparatus  400  has only one RFIC, the signals have low independency with respect to noise even though the signals respectively received in the antennas  410  are respectively input to the RFIC  420 . This is because the noise is added to the received signals by the same reason. In other words, if there is only one RFIC, it is difficult to determine and remove noise from the respective received signals since the respective received signals have high noise correlation with each other. 
     On the other hand, according to this exemplary embodiment, the plurality of RFICs  420  are respectively provided in the plurality of antennas  410  and thus individually processes the signals respectively received in the antenna  410 . The respective RFICs  420  process the received signals through their own oscillators, and there are different reasons of causing noise according to the respectively received signals. 
     The respective input signals input to the adaptive filter  440  originally include broadcast signal components and noise components. Here, the broadcast signal components involved in the respective input signals have high correlation and low independency as described above, while noise involved in the respective input signals have low correlation and high independency due to difference between the reasons of causing the noise. 
     The adaptive filter  440  gives a weight to each input signal in order to maximize the broadcast signal component and make the noise component negligible as compared with the broadcast signal component. Therefore, the signal output from the adaptive filter  440  becomes a broadcast signal with excellent reception, and the quality of a broadcast image is guaranteed when the output signal is processed. 
     Below, the process of synthesizing the input signals in the adaptive filter  440  will be described. 
     Suppose that there are a total of M antennas  410 , and let the signals respectively received in the antennas  410  be ri,j, where i is an integer from 1 to M and j is an integer from 1 to N. Here, j refers to a time index, i.e. a certain point of time. Further, let data of the signals respectively received in the antennas  410  be di,j, a center frequency of each received signal be fc, and a phase difference of each antenna  410  be θi,j. With these definitions of variables, the signals respectively received in the antennas  410  at a certain point of time j are represented by the following expressions. 
     
       
         
           
             
               
                 
                   
                     
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     If the signals respectively received in the antennas  410  have high correlation, it satisfies the following expression.
 
 d   j   =d   1,j   =d   2,j   = . . . =d   M,j   [Expression 2]
 
     If the expression 2 is substituted into the expression 1, the expression 1 can be rewritten as follows. 
     
       
         
           
             
               
                 
                   
                     
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     In the right side of the expression 3, the first term is the broadcast signal component, and the second term is the noise component. It is notable that the first term of the right side has high correlation but the second term of the right side has low correlation. Therefore, if the adaptive filter  440  gives a weight to each expression to maximize the first term of the right side and minimize the second term of the right side, it is possible to improve a signal-to-noise ratio (SNR) of an output signal from the adaptive filter  440 . 
     Let such a weight, i.e. a complex coefficient of the adaptive filter  440  be αi,j. Then, the adaptive filter  440  synthesizes the signals respectively received in the antennas  410  and outputs a signal Rj as follows. 
     
       
         
           
             
               
                 
                   
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     There are many methods of adjusting αi,j to improve the SNR. For example, there are a non-data aided method and a data aided method. 
     The non-data aided method improves the SNR of the output from the adaptive filter  440  without using a training sequence. The training sequence is a kind of reference signal embedded in a transmission signal at the transmitter for the determination of the receiver. As an example of the non-data aided method, the adaptive filter  440  limits αi,j as follows.
 
∥α i,j ∥ 2   =C   [Expression 5]
 
     where, C is greater than 0. In this state, the adaptive filter adjusts αi,j to satisfy the following expression, thereby maximizing power of Rj. 
     
       
         
           
             
               
                 
                   
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     In the Expression 5 and the Expression 6, a norm function is used. The norm function is to assign a length or size to vectors in a vector space in linear algebra and functional analysis. A zero vector has a norm of 0, and all the other vectors have positive norms. For example, a 2-norm and an infinity-norm of vectors x=[x1, x2, . . . , xn] in an n-dimensional Euclidean space Rn are respectively given satisfying the following expressions. 
     
       
         
           
             
               
                 
                   
                     
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     The data aided method improves the SNR of the output from the adaptive filter  440  with a training sequence Sj embedded in the received signal. For example, the adaptive filter  440  adjusts a complex coefficient αi,j so as to minimize a mean squared error (MSE) between Rj and sj as follows. 
     
       
         
           
             
               
                 
                   
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     With these operations, the output SNR of the adaptive filter  440  is greater than the input SNR. Ideally, it is possible to obtain an SNR gain as much as [3*Log 2 (M)] dB with regard to M antennas  410 . For instance, if there are eight antennas  410 , it is possible to improve the receiving sensitivity as much as 9 dB, and the effect of the reception is proportionally expected. 
     According to the exemplary embodiment, the plurality of antennas  410  are densely arranged, and the received signals are processed by the RFICs  420  respectively corresponding to the antennas  410  and then synthesized by the adaptive filter  440 . Thus, the image receiving apparatus  400  can improve the receiving sensitivity of the broadcast signal and guarantees the quality of a broadcast image. 
     This exemplary embodiment may be implemented in a front end part of the signal processor  350  (see  FIG. 5 ) that performs the whole processes in the image receiving apparatus  400 . This is possible because of high correlation between the signals respectively received in the antenna  410 . If the correlation is low, this exemplary embodiment has to be implemented in a rear end part of the whole processes. In this case, it is not easy to remove the noise. Accordingly, the structure according to this exemplary embodiment raises the correlation between the signals respectively received in the antennas  410  so that the noise of the broadcast signal can be more easily removed. 
     Below, a signal process according to an exemplary embodiment will be described with reference to  FIG. 8 . 
       FIG. 8  is a flowchart of a signal process in the image receiving apparatus  400   
     As shown in  FIG. 8 , at operation S 110  the image receiving apparatus  400  receives a broadcast signal through the plurality of antennas  410 . 
     At operation S 120  the image receiving apparatus  400  processes the signals respectively received in the antennas  410  through the plurality of RFICs  420 . The process performed in the RFIC  420  includes receiving a broadcast signal through the antenna  410 , and shifting the received broadcast signal from a high frequency band to an intermediate frequency band. 
     At operation S 130  the image receiving apparatus  400  inputs the signal processed by each RFIC  420  to the adaptive filter  440 . 
     At operation S 140  the image receiving apparatus  400  adjusts a weight of the adaptive filter  440  in order to improve the SNR. To adjust the weight, the non-data aided method and the data aided method may be used as described above. 
     At operation S 150  the image receiving apparatus  400  synthesizes the received signals in the adaptive filter  440 . The synthesizing operation includes an operation of assigning the adjusted weight. 
     At operation S 160  the image receiving apparatus  400  performs an image processing process with regard to the synthesized signal to thereby display a broadcast image. 
     Below, alternative exemplary embodiments reflecting the present inventive concept will be described. 
       FIG. 9  is a block diagram of an image receiving apparatus  500  according to a fifth exemplary embodiment. 
     As shown in  FIG. 9 , the image receiving apparatus  500  according to a fifth exemplary embodiment includes an antenna  510 , a low noise amplifier (LNA)  520  for amplifying a broadcast signal received in the antenna  510 , a plurality of RFICs  530 , a plurality of ADCs  540 , and an adaptive filter  550 . The RFIC  530 , the ADC  540  and the adaptive filter  550  have the same basic functions as those described above, and thus repetitive descriptions thereof will be omitted. 
     In this exemplary embodiment, a single antenna  510  is provided. According to this exemplary embodiment, a structure for improving signal reception will be described in the case of using the single antenna  510  on the contrary to those of the foregoing exemplary embodiments. 
     The LNA  520  is designed to minimize noise in order to amplify an RF signal having low intensity. The LNA  520  is positioned near the antenna  520  in order to reduce attenuation in a transmission wire. The broadcast signal received in the antenna  510  is too weak to be processed in the image receiving apparatus  500 , and therefore has to have intensity of a proper level. Thus, the LNA  520  is used to amplify the broadcast signal up to proper intensity. In particular, according to this exemplary embodiment, the signal received in the single antenna  510  has to be branched, and therefore the LNA  520  is installed at a front end before a corresponding branch point to thereby amplify the signal received in the antenna  510  and transmit the amplified signal to each of the branched RFICs  530 . 
     The RFICs  530  are provided corresponding to branches of the signals amplified by the LNA  520 . According to this exemplary embodiment, two RFICs  530  are provided corresponding to two branches. 
     The operations of the RFIC  530 , the ADC  540  and the adaptive filter  550  are the same as those of the foregoing exemplary embodiments, and thus repetitive descriptions thereof will be avoided. In this embodiment, the LNA  520  is to compensate for signal attenuation due to the branch of the signals. If the noise figure of the LNA  520  is sufficiently low, it is possible to guarantee the gain according to this exemplary embodiment. However, it is practically impossible that the noise figure of the LNA  520  is 0, and therefore the gain is lower than that of the fourth exemplary embodiment. 
     Below, a signal process according to this exemplary embodiment will be described with reference to  FIG. 10 . 
       FIG. 10  is a flowchart of a signal process in the image receiving apparatus  500 . 
     As shown in  FIG. 10 , at operation S 210  the image receiving apparatus  500  receives a broadcast signal through the single antenna  510 . 
     At operation S 220  the image receiving apparatus  500  amplifies and branches the received signal through the LNA  520 . The number of branches may be varied depending on design methods. 
     At operation S 230  the image receiving apparatus  500  processes the branched signals through the plurality of RFICs  530 . The number of RFIC  530  is equal to the number of branched signals from the LNA  520 , and each RFIC  530  shifts the received signals from a high frequency band to an intermediate frequency band. 
     At operation S 240  the image receiving apparatus  500  inputs the signal processed by each RFIC  530  to the adaptive filter  550 . 
     At operation S 250  the image receiving apparatus  500  adjusts a weight of the adaptive filter  550  in order to improve the SNR. To adjust the weight, the non-data aided method and the data aided method may be used as described above. 
     At operation S 260  the image receiving apparatus  500  synthesizes the received signals through the adaptive filter  550 . The synthesizing operation includes an operation of assigning the adjusted weight. 
     At operation S 270  the image receiving apparatus  500  performs an image processing process with regard to the synthesized signal to thereby display a broadcast image. 
       FIG. 11  is a block diagram of an image receiving apparatus  600  according to a sixth exemplary embodiment; 
     As shown in  FIG. 11 , the image receiving apparatus  600  includes a plurality of antennas groups  610 ,  620  and  630 ; a plurality of adaptive filters  640 ,  650  and  660  respectively corresponding to the antenna groups  610 ,  620  and  630 ; and a group antenna combiner  670  for synthesizing signals respectively output from the adaptive filters  640 ,  650  and  660 . The group antenna combiner may be circuitry, software, or a combination of circuitry and software. The front end structures of the adaptive filters  640 ,  650  and  660  are the same as those described above, and thus repetitive descriptions thereof will be avoided as necessary. 
     If there are a total of L antenna groups  610 ,  620  and  630 , each of the antenna groups  610 ,  620  and  630  includes a plurality of single antennas. The plurality of single antennas included in a certain antenna group  610 ,  620  or  630  are densely arranged within a circle having a diameter shorter than a half wavelength of the received signal. For example, a distance between two single antennas farthest away from each other among the plurality of single antennas in a first antenna group  610  is shorter than a half wavelength of the received signal. 
     Additionally, a distance d 3  between two adjacent antenna groups  610  and  620  is equal to or longer than a half wavelength of the received signal. For example, if the first antenna group  610  and the second antenna group  620  are closest to each other among the plurality of antennas groups  610 ,  620  and  630 , the distance d 3  between the first antenna group  610  and the second antenna group  620  is not shorter than a half wave length of the received signal. 
     Such a structure has two effects in terms of each of the antenna groups  610 ,  620  and  630  and the whole plurality of antennas groups  610 ,  620  and  630 . In the former case, each of the antenna groups  610 ,  620  and  630  includes a plurality of single antennas arranged densely, the receiving sensitivity of the antenna will be improved. In the latter case, the antenna groups  610 ,  620  and  630  are spaced apart from one another at a predetermined distance, the antenna diversity will be improved. In other words, the gain of the receiving sensitivity is gained within each of the antenna groups  610 ,  620  and  630 , and the antenna diversity is gained from the other separated antenna groups  610 ,  620  and  630 . 
     Accordingly, the broadcast signal finally synthesized and output by the group antenna combiner  670  is improved in the antenna receiving sensitivity and the antenna diversity. 
     Below, a signal process according to this exemplary embodiment will be described with reference to  FIG. 12 . 
       FIG. 12  is a flowchart of a signal process in the image receiving apparatus  600 . 
     As shown in  FIG. 12 , at operation S 310  the image receiving apparatus  600  receives a broadcast signal through the antenna groups  610 ,  620  and  630  spaced apart from one another. Each of the antenna groups  610 ,  620  and  630  includes a plurality of single antennas arranged densely, and two adjacent antenna groups  610  and  620  are spaced apart from each other at a distance equal to or longer than a half wavelength of the broadcast signal. 
     At operation S 320  the image receiving apparatus  600  individually synthesizes signals respectively received in the antenna groups  610 ,  620  and  630  through the plurality of adaptive filters  640 ,  650  and  660 . That is, each single antenna within a certain antenna group  610 ,  620  or  630  receives a broadcast signal, and the adaptive filters  640 ,  650  and  660  synthesize the signals received in the single antennas, respectively. According to this exemplary embodiment, there are a total of L antenna groups  610 ,  620  and  630  and L adaptive filters  640 ,  650  and  660 , and thus a total of L signals are input to the group antenna combiner  670 . 
     At operation S 330  the image receiving apparatus  600  synthesizes the signals respectively processed by the adaptive filters  640 ,  650  and  660  through the group antenna combiner  670 . 
     At operation S 340  the image receiving apparatus  600  processes the synthesized signals to be displayed as a broadcast image. 
     By expanding the principle of the foregoing sixth exemplary embodiment, both the indoor antenna group and the outdoor antenna may be used, and this embodiment will be described below. 
       FIG. 13  is a block diagram of an image receiving apparatus  700  according to a seventh exemplary embodiment; 
     As shown in  FIG. 13 , the image receiving apparatus  700  according to the seventh exemplary embodiment includes an indoor antenna group  710 , an outdoor antenna  720 , an adaptive filter  730 , and a group antenna combiner  740 . The indoor antenna group  710  includes a plurality of single antennas, and the respective single antennas are densely arranged within a circle having a diameter shorter than λ/2. The indoor antenna group  710  is installed indoors or the like circumstances where the receiving electric field is relatively low, and the outdoor antenna  720  is installed outdoors such as on the rooftop or the like circumstances where the receiving electric field is relatively high. Of course, the distance between the indoor antenna group  710  and the outdoor antenna  720  is longer than λ/2. 
     The operations of the adaptive filter  730  and the group antenna combiner  740  are the same as those described above, and thus repetitive descriptions thereof will be avoided as necessary. 
     With development of technology, 8 K ultra high definition (UHD) terrestrial broadcasting will be realized in the future. The UHD is also called ultra-high definition video (UHDV) or super hi-vision (SHV). In terms of color representation, while the current digital television (DTV) generally uses 8 bits, the UHD assigns 10 bits or 12 bits per channel. 
     In terms of resolution, high definition (HD) supports a resolution of 1360×768, full high definition (FHD) supports a resolution of 1920×1080, quad high definition (QHD) supports a resolution of 2560×1440, and UHD supports a resolution higher than that of QHD. 4 K UHD supports a resolution of 3840×2160, and 8 K UHD supports a resolution of 7680×4320. Further, 8 K UHD includes about 33 million pixels. 
     To display a broadcast image by receiving a UHD broadcast signal, it is important to improve the reception of the broadcast signal transmitted from the transmitter (not shown) of the broadcasting station. To this end, the broadcast signal is received through many antennas, and the broadcast signals respectively received in the antennas are synthesized, thereby finally obtaining a signal with excellent quality. Taking these circumstances into account, the indoor antenna group  710  is added to the circumstances where the outdoor antenna  720  is installed, so that 8 K UHD terrestrial broadcasting or the like broadcast image having a very high resolution can be provided. 
     Additionally, when two or more signals are synthesized to finally obtain a signal with high quality and low noise, difference in quality between the signals to be synthesized has to be within an allowable range. 
     If a single indoor antenna is installed in the state that the outdoor antenna has been installed, the broadcast signal received in the outdoor antenna and the broadcast signal received in the single indoor antenna are very different in quality from each other. Specifically, the quality of the broadcast signal received in the single indoor antenna is significantly lower than that of the broadcast signal received in the outdoor antenna, and therefore it is therefore difficult to get a sufficient gain even though two signals are synthesized. 
     On the other hand, according to this exemplary embodiment, the adaptive filter  730  synthesizes the broadcast signals respectively received in the single antennas included in the indoor antenna group  710  and outputs it to the group antenna combiner  740 . Further, the broadcast signal received in the outdoor antenna  720  is input to the group antenna combiner  740 . According to the operations of the foregoing exemplary embodiments, the broadcast signal output from the adaptive filter  730  is improved in quality up to a level approximate to that of the outdoor antenna  720 . 
     The group antenna combiner  740  synthesizes the signal from the adaptive filter  730  and the signal from the outdoor antenna  720 , and thus finally gets a broadcast signal with high quality. With this process, the image receiving apparatus  700  receives a broadcast signal of 8 K UHD terrestrial broadcasting or the like UHD broadcast signal and displays a broadcast image with good quality. 
     Below, a signal process according to an exemplary embodiment will be described with reference to  FIG. 14 . 
       FIG. 14  is a flowchart of a signal process in the image receiving apparatus  700 . 
     As shown in  FIG. 14 , at operation S 410  the image receiving apparatus  700  receives a broadcast signal through the indoor antenna group  710 . 
     At operation S 420  the image receiving apparatus  700  synthesizes the broadcast signals respectively received in the single antennas in the indoor antenna group  710  through the adaptive filter  730 . 
     At operation S 430  the image receiving apparatus  700  receives the broadcast signal through the outdoor antenna  720 . 
     At operation S 440  the image receiving apparatus  700  synthesizes the signal from the adaptive filter  730  and the signal from the outdoor antenna  720 . 
     At operation S 450  the image receiving apparatus  700  processes the synthesized signal and displays a broadcast image. 
     In the foregoing embodiment, each of the indoor antenna group  710 , the adaptive filter  730  and the outdoor antenna  720  is one, but not limited thereto. Alternatively, each of the indoor antenna group  710  and the corresponding adaptive filter  730  may be two or more. 
       FIG. 15  is a block diagram of an image receiving apparatus  800  according to an eighth exemplary embodiment. 
     As shown in  FIG. 15 , the image receiving apparatus  800  according to the eighth exemplary embodiment includes a plurality of indoor antenna groups  810  and  820 , and a plurality of adaptive filter  840  and  850  respectively corresponding to the plurality of indoor antenna groups  810  and  820 , and a group antenna combiner  860 . The operations of the adaptive filters  840  and  850  and the group antenna combiner  860  are the same as those described above, and thus repetitive descriptions thereof will be avoided. 
     According to this exemplary embodiment, a first indoor antenna group  810  and a second indoor antenna group  820  are installed. Of course, three or more indoor antenna groups  810  and  820  may be installed. Each of the indoor antenna groups  810  and  820  includes a plurality of single antennas, and the single antennas in each of the indoor antenna groups  810  and  820  are densely arranged within a circle having a diameter shorter than λ/2. Thus, it will be expected that the signal receiving sensitivity is improved by the respective indoor antenna groups  810  and  820 . 
     However, a distance d 4  between the first indoor antenna group  810  and the second indoor antenna group  820 , adjacent to each other, is equal to or longer than λ/2. Therefore, it will be expected that the antenna diversity effect is improved in terms of the whole indoor antenna groups  810  and  820 . 
     If the plurality of indoor antenna groups  810  and  820  are provided according to this exemplary embodiment, the antenna diversity is more improved than that of the foregoing seventh exemplary embodiment. 
     Below, a signal process according to an exemplary embodiment will be described with reference to  FIG. 16 . 
       FIG. 16  is a flowchart of a signal process in the image receiving apparatus  800 . 
     As shown in  FIG. 16 , at operation S 510  the image receiving apparatus  800  receives a broadcast signal through each of the plurality of indoor antenna groups  810  and  820 . Each of the indoor antenna groups  810  and  820  includes a plurality of single antennas densely arranged within a circle having a diameter shorter than a half wavelength of the broadcast signal, and a distance between two adjacent antenna groups  810  and  820  is longer than a half wavelength of the broadcast signal. 
     At operation S 520  the image receiving apparatus  800  synthesizes the signals respectively received in the indoor antenna groups  810  and  820  through plurality of adaptive filters  840  and  850 , respectively. That is, the single antennas in a certain antenna group  810  or  820  respectively receive the broadcast signals, and the adaptive filters  840  and  850  respectively synthesize the signals respectively received in the single antennas. 
     At operation S 530  the image receiving apparatus  800  receives the broadcast signal through the outdoor antenna  830 . 
     At operation S 540  the image receiving apparatus  800  synthesizes the signals from the respective adaptive filters  840  and  850  and the signal from the outdoor antenna  830 . 
     At operation S 550  the image receiving apparatus  800  processes the synthesized signal and displays a broadcast image based on the processed signal. 
       FIG. 17  illustrates a user interface (UI) to be displayed on an image receiving apparatus  900  according to a ninth exemplary embodiment. 
     As shown in  FIG. 17 , the image receiving apparatus  900  according to the ninth exemplary embodiment is connected to one or more indoor antenna groups  910  and an outdoor antenna  920 . In this state, the image receiving apparatus  900  displays a UI  930 , through which the antennas  910  and  920  to be used for receiving the broadcast signal is selected by a user, in response to a preset event. The preset event may be generated by a user&#39;s preset input, or may be automatically generated when the broadcast signal is first sensed by the antennas  910  and  920 . 
     When the UI  930  is displayed, a user may select one among options displayed on the UI  930 . The image receiving apparatus  900  operates based on the options selected by a user. The options displayed on the UI  930  may include a case of using only the indoor antenna group  910  to receive the broadcast signal, a case of using only the outdoor antenna  920  to receive the broadcast signal, and a case of using both the indoor antenna group  910  and the outdoor antenna  920  to receive the broadcast signal. 
     A user may properly select the option in consideration of the characteristics of the broadcast signal to be received and the receiving circumstances of the image receiving apparatus  900 . For example, if the broadcast signal corresponds to a relatively low image quality, a user may use only one of the indoor antenna group  910  and the outdoor antenna  920  to receive the broadcast signal. On the other hand, if the broadcast signal corresponds to a relatively high image quality, a user may select the option of using both the indoor antenna group  910  and the outdoor antenna  920  to receive the broadcast signal since the reception quality of the broadcast signal is very important. 
       FIG. 18  is a block diagram of the image receiving apparatus  900 . 
     As shown in  FIG. 18 , the image receiving apparatus  900  includes a switch  940 , an adaptive filter  950 , and a group antenna combiner  960 . The operations of the adaptive filter  950  and the group antenna combiner  960  are substantially the same as those described as above. 
     The switch  940  is installed on a path of transferring the broadcast signal received in each of the indoor antenna group  910  and the outdoor antenna  920 . The switch  940  selectively prevents the broadcast signal received in the indoor antenna group  910  from being transmitted to the adaptive filter  950 , or selectively prevents the broadcast signal received in the outdoor antenna  920  from being transmitted to the group antenna combiner  960 . The operation of the switch  940  may be controlled by a microcontroller, a CPU or the like separate element provided in the image receiving apparatus  900 . 
     The switch  940  may be arranged in a front end of the adaptive filter  950  rather than a rear end in order to prevent the adaptive filter  950  from processing the broadcast signal in the case that the indoor antenna group  910  is not used. However, alternatively, the switch  940  may be arranged on the path of signal transmission between the adaptive filter  950  and the group antenna combiner  960 . 
     If a user selects the option of using only the indoor antenna group  910  through the UI  930  (see  FIG. 17 ), the switch  940  allows the broadcast signal received in the indoor antenna group  910  to be transmitted to the adaptive filter  950  but prevents the broadcast signal received in the outdoor antenna  920  from being transmitted to the group antenna combiner  960 . 
     If a user selects the option of using only the outdoor antenna  920 , the switch  940  prevents the broadcast signal received in the indoor antenna group  910  from being transmitted to the adaptive filter  950  but allows the broadcast signal received in the outdoor antenna  920  to be transmitted to the group antenna combiner  960 . 
     If a user selects the option of using both the indoor antenna group  910  and the outdoor antenna  920 , the switch  940  allows the broadcast signal received in the indoor antenna group  910  to be transmitted to the adaptive filter  950  and allows the broadcast signal received in the outdoor antenna  920  to be transmitted to the group antenna combiner  960 . 
     The group antenna combiner  960  processes the signal in accordance with the options. For example, if the signals are received from both the adaptive filter  950  and the outdoor antenna  920 , the group antenna combiner  960  synthesizes the received signals. On the other hand, if the signal is received from only one of the adaptive filter  950  and the outdoor antenna  920 , the group antenna combiner  960  outputs the signals to be processed by the next process since there is no need of a signal synthesizing process. 
     In the foregoing exemplary embodiments, the terrestrial broadcasting was described. However, the exemplary embodiments may be applicable to cable broadcasting, satellite broadcasting, etc. In the case of the cable broadcasting, the antennas of the foregoing exemplary embodiments may be replaced by cables. Further, in the case of the satellite broadcasting, the antennas of the foregoing exemplary embodiments may be replaced by satellite antennas. 
     Further, the foregoing exemplary embodiments described the image receiving apparatus. However, the exemplary embodiments may also be applied to a wireless communication solution such as Wi-Fi, Bluetooth, etc. as well as the image receiving apparatus such as an image processing apparatus, a display apparatus, etc. 
       FIG. 19  illustrates a system  1100  according to a tenth exemplary embodiment. 
     As shown in  FIG. 19 , the system  1100  according to the tenth exemplary embodiment includes an access point (AP)  1110 , and at least one external apparatuses  1120  and  1130  wirelessly connected to the AP  1110 . According to this exemplary embodiment, the AP  1110  for relaying interactive wireless communication is provided as an example of the relay, but not limited thereto. The AP  1110  may be replaced by a device for wirelessly transmitting signals received in the plurality of antennas  1140  to the external apparatuses  1120  and  1130  without the interactive wireless communication. 
     The AP  1110  is a device that relays communication so that the external apparatuses  1120  and  1130  can wirelessly connect with a computer network through Wi-Fi or the like wireless communication standards. The AP  1110  is connected to a router generally using a wired network, so that the external apparatuses  1120  and  1130  can do wireless interactive communication with the wired network. 
     The external apparatuses  1120  and  1130  may wirelessly connect with the AP  1110  and perform communication via the AP  1110 . To this end, each of the external apparatuses  1120  and  1130  includes a wireless communication module for communication with the AP  1110 . 
     The AP  1110  is provided with a plurality of single antennas  1140 . The single antennas  1140  are densely arranged within a circle having a diameter shorter than λ/2. The AP  1110  processes a signal received through the plurality of antennas  1140  and wirelessly transmits it to the external apparatuses  1120  and  1130  while connecting with the wired network. 
       FIG. 20  is a block diagram of the AP  1110 . 
     As shown in  FIG. 20 , the AP  1110  is individually provided corresponding to the plurality of antennas  1140  and thus includes a plurality of RFICs  1111  for receiving RF signals respectively received in the antennas  1140 , a plurality of ADCs  1112  for converting analog signals respectively output from the RFICs  1111  into digital signals, an adaptive filter  1113  for synthesizing the digital signals respectively output from the ADC  1112 , and a communicator  1114  for wirelessly transmitting the synthesized signal from the adaptive filter  1113  to the external apparatus  1120  or  1130 . 
     The process of synthesizing the RF signals respectively received in the plurality of antennas  1140  through the adaptive filter  1113  is substantially the same as that described above, and thus repetitive descriptions thereof will be avoided. The communicator  1114  may change the synthesized signal output from the adaptive filter  1113  in accordance with preset communication standards so that the synthesized signal can be wirelessly transmitted to the external apparatus  1120 . Alternatively, the communicator  1114  may transmit the synthesized signal to the external apparatus  1120  not wirelessly but using a wire. 
     Thus, the foregoing structure of transmitting the synthesized signal to the external apparatuses  1120  and  1130  through the relay  1110  having the plurality of antennas  1140  has advantages as follows. As described in the foregoing exemplary embodiments, the plurality of antennas  1140  have to be densely arranged within a circle having a diameter shorter than λ/2 and the RFICs  1111  have to be provided corresponding to the respective antennas  1140  in order to raise the sensitivity of receiving the RF signal. 
     However, the TV or the like external apparatuses  1120  and  1130  may have only one RFIC  1111  or have the RFICs  111  that do not correspond to the number of antennas  1140 . This situation may occur if the external apparatus  1120  or  1130  is first purchased without considering the antennas  1140  to be installed at the indoor circumstances, and then the antennas  1140  are additionally installed indoors in order to improve the reception of the broadcast signal. 
     Thus, a user can obtain the foregoing effects by installing the relay  1110  having the plurality of antennas  1140  without changing the existing external apparatuses  1120  and  1130 . 
     The methods according to the foregoing exemplary embodiments may be achieved in the form of a program command that can be implemented in various computers, and recorded in a computer readable medium. Such a computer readable medium may include a program command, a data file, a data structure or the like, or combination thereof. For example, the computer readable medium may be stored in a voltage or nonvolatile storage such as a read only memory (ROM) or the like, regardless of whether it is deletable or rewritable, for example, a RAM, a memory chip, a device or integrated circuit (IC) like memory, or an optically or magnetically recordable or machine (e.g., a computer)-readable storage medium, for example, a compact disk (CD), a digital versatile disk (DVD), a magnetic disk, a magnetic tape or the like. It will be appreciated that a memory, which can be included in a mobile terminal, is an example of the machine-readable storage medium suitable for storing a program having instructions for materializing the exemplary embodiments. The program command recorded in this storage medium may be specially designed and configured according to the exemplary embodiments. 
     Although a few exemplary embodiments have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.