Patent Publication Number: US-2023164005-A1

Title: Signal processing device and image display device having same

Description:
BACKGROUND 
     1. Field of the Present Disclosure 
     The present disclosure relates to a signal processing device and an image display apparatus including the same, and more particularly, to a signal processing device and an image display apparatus including the same which can improve performances of burst noise and narrow band noise. 
     2. Description of the Related Art 
     A signal processing device is a device for receiving and processing a terrestrial digital broadcasting signal and a mobile communication signal. 
     The signal processing device receives an RF signal, including noise from a communication channel, via an antenna, and performs signal processing on the received RF signal. 
     For example, upon the signal processing in the signal processing device, channel state information (CSI) is calculated by assuming that a channel environment is additive white Gaussian noise (AWGN). 
     However, an actual channel environment does not depend on the additive white Gaussian noise, and has a problem in that the performance deteriorates in a specific channel environment, e.g., impulsive interference or co-channel interference. 
     In particular, there is a problem in that performance deterioration by burst noise according to the impulse interference or narrow band noise according to the co-channel interference. 
     SUMMARY 
     It is an object of the present disclosure to provide a signal processing device and an image display apparatus including the same which can improve performances for burst noise and narrow band noise. 
     It is another object of the present disclosure to provide a signal processing device and an image display apparatus including the same which can selectively perform time interpolation according to a channel. 
     It is another object of the present disclosure to provide a signal processing device and an image display apparatus including the same for stably ensuring data even in a mobile channel environment. 
     In accordance with an aspect of the present disclosure, the above objects can be accomplished by providing a signal processing device and an image display apparatus including the same, including a synchronizer configured to perform a Fourier transform based on the received baseband signal; and an equalizer configured to calculate a channel transfer function value, symbol based noise, and subcarrier frequency based noise based on the signal from the synchronizer, and calculate channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise. 
     Meanwhile, in accordance with another aspect of the present disclosure, the above objects can be accomplished by providing a signal processing device and an image display apparatus including the same, including a synchronizer configured to remove a guard band based on the received baseband signal; and an equalizer configured to calculate a channel transfer function value, symbol based noise, and subcarrier frequency based noise based on the signal from the synchronizer, and calculate channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise. 
     EFFECTS OF THE DISCLOSURE 
     A signal processing device and an image display apparatus including the same according to an embodiment of the present disclosure include a synchronizer performing Fourier transform based on a received baseband signal, and an equalizer computing a channel transfer function value, symbol based noise, and subcarrier frequency based noise based on a signal from the synchronizer, and computing channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise. As a result, performances for burst noise and narrow band noise can be improved. 
     Meanwhile, the equalizer may extract a pilot signal from the signal from the synchronizer, and calculate the channel transfer function value based on the extracted pilot signal. As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the equalizer may extract the pilot signal from the signal from the synchronizer, and calculate the symbol based noise and the subcarrier frequency based noise based on the extracted pilot signal. As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the equalizer may calculate symbol index based noise and subcarrier index based noise based on the signal from the synchronizer. As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the equalizer may calculate channel state information which is in proportion to power of the channel transfer function value, which is in inverse proportion to power of the symbol based noise, and which is in inverse proportion to power of the subcarrier frequency based noise. As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the equalizer may calculate a log-likelihood ratio based on the channel state information. As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the signal processing device and the image display apparatus including the same according to an embodiment of the present disclosure may further include an error corrector performing error correction based on the channel state information. As a result, the performances for the bust noise and the narrow band noise may be improved. Further, the data may be stably ensured. 
     Meanwhile, the erector corrector may perform the error correction based on a mean square error which increases as a level of the channel state information decreases. As a result, the performances for the bust noise and the narrow band noise may be improved. Further, the data may be stably ensured. 
     Meanwhile, the equalizer may calculate a channel transfer function value, symbol based noise, and subcarrier frequency based noise based on the signal from the synchronizer, and calculate channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise. As a result, the time interpolation may be selectively performed according to a channel. In particular, the data may be stably ensured even in the mobile channel environment. In addition, the channel estimation accuracy is improved. 
     Meanwhile, the equalizer may turn off the time interpolation and perform frequency interpolation in response to a difference in the channel transfer function value of the pilot signal being equal to or more than a reference value between a previous subframe and a current subframe. As a result, in the case of the mobile channel, the time interpolation is turned off to stably ensure the data. 
     Meanwhile, the equalizer may perform the time interpolation and the frequency interpolation in response to the difference in the channel transfer function value of the pilot signal being less than the reference value between a previous subframe and a current subframe. As a result, in the case of the static channel other than the mobile channel, the time interpolation and the frequency interpolation are performed to stably ensure the data. 
     Meanwhile, the equalizer may estimate that the channel is the mobile channel in response to the difference in the channel transfer function value of the pilot signal being equal to or more than the reference value between the previous subframe and the current subframe. As a result, in the case of the mobile channel, the time interpolation is turned off to stably ensure the data. In addition, the channel estimation accuracy is improved. 
     Meanwhile, the equalizer may estimate that the channel is the static channel in response to the difference in the channel transfer function value of the pilot signal being less than the reference value between the previous subframe and the current subframe. As a result, in the case of the static channel, the time interpolation and the frequency interpolation are performed to stably ensure the data. In addition, the channel estimation accuracy is improved. 
     Meanwhile, the equalizer may determine whether to perform the time interpolation based on the calculated channel transfer function value before performing the time interpolation. As a result, the channel estimation accuracy is improved, and as a result, the data may be stably ensured. 
     Meanwhile, the equalizer may turn off the time interpolation and perform the frequency interpolation in response to a difference between a representative value of the channel transfer function value of the pilot signal in the previous subframe and the representative value of the channel transfer function of the pilot signal in the current subframe being equal to or more than a reference value. As a result, the time interpolation may be selectively performed according to a channel. In particular, the data may be stably ensured even in the mobile channel environment. 
     Meanwhile, the reference value may be varied according to the moving speed or mode of the signal processing device. As a result, the time interpolation may be selectively performed according to a channel. In particular, the data may be stably ensured even in the mobile channel environment. 
     Meanwhile, the equalizer may turn off the time interpolation and perform the frequency interpolation from the next subframe in response to a difference in the channel transfer function value of the pilot signal being equal to or more than a reference value between a previous subframe and a current subframe. As a result, the time interpolation may be selectively performed according to a channel. In particular, the data may be stably ensured even in the mobile channel environment. 
     Meanwhile, the equalizer may turn off the time interpolation and perform the frequency interpolation from a current subframe in response to a difference in the channel transfer function value of the pilot signal being equal to or more than a reference value between a previous subframe and a current subframe. As a result, the time interpolation may be selectively performed according to a channel. In particular, the data may be stably ensured even in the mobile channel environment. 
     Meanwhile, the equalizer may turn off the time interpolation and changes an off time of the time interpolation according to the moving speed or mode of the signal processing device, in response to the difference in the channel transfer function value of the pilot signal being equal to or more than the reference value between the previous subframe and the current subframe. By varying the off time, the data may be stably ensured adaptively to the moving speed or mode. 
     Meanwhile, when the first subframe and the second subframe in one frame have different transport formats, the equalizer may perform control to make the threshold for the first subframe and the threshold for the second subframe different from each other. By varying the threshold based on transport formats, the data may be stably ensured. In addition, the channel estimation accuracy is improved. 
     Meanwhile, the synchronizer may remove a cyclic prefix based on the received baseband signal before the Fourier transform and remove a guard band after the Fourier transform. Further, the data may be stably ensured. 
     Meanwhile, the synchronizer may perform timing restoration based on the received baseband signal before removing the cyclic prefix. Further, the data may be stably ensured. 
     Meanwhile, a signal processing device and an image display apparatus including the same according to another embodiment of the present disclosure include an equalizer computing a channel transfer function value, symbol based noise, and subcarrier frequency based noise based on a signal from a synchronizer, and computing channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise. As a result, performances for burst noise and narrow band noise can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram illustrating a radio frequency (RF) signal receiving system according to an embodiment of the present disclosure; 
         FIG.  2 A  is a diagram showing an example of an image display apparatus according to an embodiment of the present disclosure; 
         FIG.  2 B  is a diagram showing another example of an image display apparatus according to an embodiment of the present disclosure; 
         FIG.  3    is an internal block diagram of the image display apparatus of  FIG.  2 A ; 
         FIG.  4    is an internal block diagram of the controller of  FIG.  3   ; 
         FIGS.  5 A to  5 B  are diagrams for explaining a static channel and a mobile channel; 
         FIGS.  6 A to  6 C  are diagrams for explaining interpolation based on a pilot signal; 
         FIG.  7    is a flowchart of a method of operating a signal processing device related to the present disclosure; 
         FIG.  8    is a flowchart of a method of operating a signal processing device according to an embodiment of the present disclosure; 
         FIG.  9 A  is a block diagram illustrating an RF signal receiving system according to an embodiment of the present disclosure; 
         FIG.  9 B  is a block diagram illustrating an example of an RF receiving device according to an embodiment of the present disclosure; 
         FIG.  9 C  is a block diagram illustrating an example of an RF receiving device according to another embodiment of the present disclosure; 
         FIG.  9 D  is an internal block diagram showing an example of the signal processing device of  FIG.  9 B or  9 C ; and 
         FIGS.  10 A to  12    are diagrams referenced for explaining an operation method of  FIG.  8   . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of the present disclosure will be described in further detail with reference to the accompanying drawings. 
     In the following description, the terms “module” and “unit”, which are used herein to signify components, are merely intended to facilitate explanation of the present disclosure, and the terms do not have any distinguishable difference in meaning or role. Thus, the terms “module” and “unit” may be used interchangeably. 
       FIG.  1    is a diagram illustrating a radio frequency (RF) signal receiving system according to an embodiment of the present disclosure. 
     Referring to  FIG.  1   , an RF signal receiving system  10  according to an embodiment of the present disclosure may include a wireless signal transmitting device  10  for transmitting an RF signal CA, and a wireless reception device  80  for receiving the RF signal CA. 
     The RF reception device  80  according to an embodiment of the present disclosure may be an RF reception device that does not depend on additive white Gaussian noise, and may reduce performance deterioration by burst noise or performance deterioration by narrow band noise in a specific channel environment, e.g., impulsive interference or co-channel interference. 
     To this end, the RF reception device  80  (in  FIG.  9 A ) according to an embodiment of the present disclosure may include a synchronizer  521  (in  FIG.  9 B ) performing Fourier transform based on a received baseband signal, and a signal processing device  520  (in  FIG.  9 B ) including an equalizer  523  (in  FIG.  9 B ) computing a channel transfer function value, symbol based noise, and subcarrier frequency based noise based on a signal from the synchronizer, and computing channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise. As a result, performances for burst noise and narrow band noise can be improved. 
     Meanwhile, the RF reception device  80  (in  FIG.  9 A ) according to another embodiment of the present disclosure may include a synchronizer  521  (in  FIG.  9 B ) removing a guard band based on a received baseband signal, and a signal processing device  520  (in  FIG.  9 B ) including an equalizer  523  (in  FIG.  9 B ) computing a channel transfer function value, symbol based noise, and subcarrier frequency based noise based on a signal from the synchronizer, and computing channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise. As a result, performances for burst noise and narrow band noise can be improved. 
     The RF signal CA of  FIG.  1    may be a digital broadcasting signal, and in this case, the RF receiving device  80  of  FIG.  1    may be included in an image display device  100  (refer to  FIG.  2 A ) such as a TV or a mobile terminal  100   b  (refer to  FIG.  2 B ) such as a cellular phone or a tablet terminal. 
     The RF signal CA may be a broadcasting signal based on the ATSC 3.0 standard. 
       FIG.  2 A  is a diagram showing an example of an image display apparatus according to an embodiment of the present disclosure. 
     Referring to  FIG.  2 A , the image display apparatus  100  of  FIG.  2 A  may include a display  180  and may also include the RF receiving device  80  described with reference to  FIG.  1   . 
     An image display apparatus  100  in  FIG.  2 A  may include a signal processing device performing Fourier transform based on a received baseband signal, and computing a channel transfer function value, symbol based noise, and subcarrier frequency based noise, and computing channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise after performing the Fourier transform. 
     As a result, performances for burst noise and narrow band noise can be improved. 
     Meanwhile, an image display apparatus  100  in  FIG.  2 A  may include a signal processing device removing a guard band based on a received baseband signal, and computing a channel transfer function value, symbol based noise, and subcarrier frequency based noise, and computing channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise after removing the guard band. 
     As a result, performances for burst noise and narrow band noise can be improved. 
       FIG.  2 B  is a diagram illustrating another example of an image display apparatus according to an embodiment of the present disclosure. 
     Referring to  FIG.  2 B , a mobile terminal  100   b  of  FIG.  2 B  may include a display  180   b,  and further, include the RF reception device  80  described in  FIG.  1   . 
     The mobile terminal  100   b  in  FIG.  2 B  may include a signal processing device performing Fourier transform based on a received baseband signal, and computing a channel transfer function value, symbol based noise, and subcarrier frequency based noise, and computing channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise after performing the Fourier transform. 
     As a result, performances for burst noise and narrow band noise can be improved. 
     Meanwhile, the image display apparatus  100 B in  FIG.  2 B  may include a signal processing device removing a guard band based on a received baseband signal, and computing a channel transfer function value, symbol based noise, and subcarrier frequency based noise, and computing channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise after removing the guard band. 
     As a result, performances for burst noise and narrow band noise can be improved. 
       FIG.  3    is an internal block diagram of the image display apparatus of  FIG.  2 A . 
     Referring to  FIG.  3   , the image display apparatus  100  according to an embodiment of the present disclosure comprises a broadcast receiver  105 , an external device interface  130 , a memory  140 , a user input interface  150 , a sensor device (not shown), a signal processor, the display  180 , and an audio output device  185 . 
     The broadcast receiver  105  includes a tuner module  110 , a demodulator  120 , a network interface  135 , and an external device interface  130 . 
     Unlike the embodiment of  FIG.  3   , the demodulator  120  may be included in the tuner module  110 . 
     Further, unlike the embodiment of  FIG.  3   , the broadcast receiver  105  may include only the tuner module  110 , the demodulator  120 , and the external interface  135 , i.e., without including the network interface  135 . 
     The tuner module  110  may tune a Radio Frequency (RF) broadcast signal corresponding to a channel selected by a user or all the previously stored channels, among RF broadcast signals received via an antenna (not shown). In addition, the tuner module  110  may convert the tuned RF broadcast signal into an intermediate frequency signal or a baseband signal (baseband image signal or baseband audio signal). 
     For example, if the selected RF broadcast signal is a digital broadcast signal, the tuner module  110  converts the digital broadcast signal into a digital IF signal (DIF), and if the selected RF broadcast signal is an analog broadcast signal, the tuner module  110  converts the analog broadcast signal into a baseband image or an audio signal (CVBS/SIF). That is, the tuner module  110  may process the digital broadcast signal or the analog broadcast signal. The analog baseband image or the audio signal (CVBS/SIF), which is output from the tuner module  110 , may be directly input to the signal processor. 
     The tuner module  110  may include a plurality of tuners to receive broadcast signals of a plurality of channels. Alternatively, the tuner module  110  may be a single turner which receives broadcast signals of a plurality of channels simultaneously. 
     The demodulator  120  may receive the digital IF (DIF) signal converted by the tuner module  110 , and may demodulate the digital IF signal. 
     For example, the demodulator  120  may convert the digital IF (DIF) signal, which is converted by the tuner module  110 , into a baseband signal. 
     Upon performing demodulation and channel decoding, the demodulator  120  may output a stream signal (TS). Here, the stream signal may be a signal obtained by multiplexing an image signal, an audio signal, or a data signal. 
     The stream signal, output from the demodulator  120 , may be input into the signal processor. Upon performing demultiplexing, A/V signal processing, and the like, the signal processor may output video to the display  180  and audio to the audio output device  185 . 
     The external device interface  130  may be connected to an external device (not shown), e.g., a set-top box  50 , to transmit or receive data. To this end, the external device interface  130  may include an A/V input and output device (not shown). 
     The external device interface  130  may be connected, wirelessly or by wire, to an external device, such as a digital versatile disk (DVD), a Blu-ray, a game console, a camera, a camcorder, a calculator (laptop calculator), a set-top box, and the like, and may perform an input/output operation with the external device. 
     The A/V input/output device may receive input of image and audio signals of the external device. A wireless communicator (not shown) may perform short range wireless communication with other electronic devices. 
     By connection with such wireless communicator (not shown), the external device interface  130  may exchange data with an adjacent mobile terminal  160 . Particularly, in a mirroring mode, the external device interface  130  may receive device information, information on executed applications, application images, and the like from the mobile terminal  600 . 
     The network interface  135  serves as an interface for connecting the image display apparatus  100  and a wired or wireless network such as the Internet. For example, the network interface  135  may receive contents or data from the Internet, a content provider, or a network operator over a network. 
     Further, the network interface  135  may include the wireless communicator (not shown). 
     The memory  140  may store programs for processing and controlling each signal by the signal processor, or may store processed video, audio, or data signals. 
     In addition, the memory  140  may also temporarily store video, audio, or data signals input via the external device interface  130 . Furthermore, the memory  140  may store information related to a predetermined broadcast channel using a channel memory function of a channel map and the like. 
     While  FIG.  3    illustrates an example where the memory  140  is separately provided from the signal processor, the present disclosure is not limited thereto, and the memory  140  may be included in the signal processor. 
     The user input interface  150  transmits a signal, input by a user, to the signal processor, or transmits a signal from the signal processor to the user. 
     For example, the user input interface  150  may transmit/receive user input signals, such as a power on/off signal, a channel selection signal, a screen setting signal, and the like, to and from a remote controller  200 ; may transfer a user input signal, which is input from a local key (not shown), such as a power key, a channel key, a volume key, or a setting key, to the signal processor; may transfer a user input signal, which is input from a sensor device (not shown) for sensing a user&#39;s gesture, to the signal processor; or may transmit a signal from the signal processor to the sensor device (not shown). 
     The signal processor may demultiplex stream, which is input via the tuner module  110 , the demodulator  120 , a network interface  135 , or the external interface  130 , or may process the demultiplexed signals, to generate and output signals for outputting video or audio. 
     The video signal processed by the signal processor may be input to the display  180  to be output as a video corresponding to the video signal. Further, the video signal processed by the signal processor may be input to an external output device via the external device interface  130 . 
     The audio signal processed by the signal processor may be output to the audio output device  185 . Further, the audio signal processed by the signal processor may be input to the external output device through the external device interface  130 . 
     Although not illustrated in  FIG.  3   , the signal processor may include a demultiplexer, a video processor, and the like, which will be described later with reference to  FIG.  4   . 
     In addition, the signal processor may control the overall operation of the image display apparatus  100 . For example, the signal processor may control the tuner module  110  to tune to an RF broadcast corresponding to a user selected channel or a prestored channel. 
     Further, the signal processor may control the image display apparatus  100  by a user command input via the user input interface  150  or an internal program. 
     For example, the signal processor may control the display  180  to display an image. In this case, the image displayed on the display  180  may be a still image or a video, or a 2D or 3D image. 
     In addition, the signal processor may control the display  180  to display a predetermined object in the displayed image. For example, the object may be at least one of an accessed web screen (newspaper, magazine, etc.), an Electronic Program Guide (EPG), various menus, a widget, an icon, a still image, a video, or text. 
     The signal processor may recognize a user&#39;s location based on an image captured by a capturing device (not shown). For example, the signal processor may recognize a distance (z-axial coordinates) between the user and the image display apparatus  100 . Also, the signal processor may recognize x-axial coordinates and y-axial coordinates in the display  180  corresponding to the user&#39;s location. 
     The display  180  converts a video signal, a data signal, an OSD signal, a control signal which are processed by the signal processor, or a video signal, a data signal, a control signal, and the like which are received via the external device interface  130 , to generate a driving signal. 
     Further, the display  180  may be implemented as a touch screen to be used as an input device as well as an output device. 
     The audio output device  185  may output sound by receiving an audio signal processed by the signal processor. 
     The capturing device (not shown) captures a user&#39;s image. The capturing device (not shown) may be implemented with a single camera, but is not limited thereto, and may be implemented with a plurality of cameras. The image information captured by the capturing device (not shown) may be input to the signal processor. 
     The signal processor may sense a user&#39;s gesture based on the image captured by the capturing device (not shown), a signal sensed by the sensor device (not shown), or a combination thereof. 
     The power supply  190  may supply power throughout the image display apparatus  100 . Particularly, the power supply  190  may supply power to the signal processor which may be implemented in a form of a system on chip (SOC), the display  180  to display an image, and the audio output device  185  to output an audio. 
     Specifically, the power supply  190  may include a converter which converts an alternating current into a direct current, and a dc/dc converter which converts the level of the direct current. 
     The remote controller  200  transmits a user input to the user input interface  150 . To this end, the remote controller  200  may use various communication techniques, such as Bluetooth, RF communication, IR communication, Ultra Wideband (UWB), ZigBee, and the like. Further, the remote controller  200  may receive video, audio, or data signals output from the user input interface  150 , to display the signals on the remote controller  200  or output the signal thereon in the form of sound. 
     The above described image display apparatus  100  may be a fixed or mobile digital broadcast receiver capable of receiving digital broadcast. 
     The block diagram of the image display apparatus  100  illustrated in  FIG.  3    is only by example. Depending upon the specifications of the image display apparatus  100  in actual implementation, the components of the image display apparatus  100  may be combined or omitted or new components may be added. That is, two or more components may be incorporated into one component or one component may be configured as separate components, as needed. In addition, the function of each block is described for the purpose of describing the embodiment of the invention and thus specific operations or devices should not be construed as limiting the scope and spirit of the invention. 
       FIG.  4    is an internal block diagram of the controller of  FIG.  3   . 
     Referring to  FIG.  4   , the signal processor according to an embodiment of the present disclosure comprises a demultiplexer  310 , a video processor  320 , a processor  330 , an OSD processor  340 , a mixer  345 , a frame rate converter  350 , and a formatter  360 . In addition, the processor  170  may further include an audio processor (not shown) and a data processor (not shown). 
     The demultiplexer  310  demultiplexes an input stream. For example, the demultiplexer  310  may demultiplex an MPEG-2 TS into a video signal, an audio signal, and a data signal. Here, the stream signal input to the demultiplexer  310  may be a stream signal output from the tuner module  110 , the demodulator  120 , or the external device interface  130 . 
     The video processor  320  may process the demultiplexed video signal. To this end, the video processor  320  may include a video decoder  325  and a scaler  335 . 
     The video processor  325  decodes the demultiplexed video signal, and the scaler  335  scales resolution of the decoded video signal so that the video signal may be displayed on the display  180 . 
     The video decoder  325  may include decoders of various standards. Examples of the video decoder  325  may include an MPEG-2 decoder, an H.264 decoder, a 3D video decoder for decoding a color image and a depth image, a decoder for decoding an image having a plurality of viewpoints, and the like. 
     The processor  330  may control the overall operation of the image display apparatus  100  or the signal processor. For example, the processor  330  controls the tuner module  110  to tune to an RF signal corresponding to a channel selected by the user or a previously stored channel. 
     The processor  330  may control the image display apparatus  100  by a user command input through the user input interface  150  or an internal program. 
     Further, the processor  330  may control data transmission of the network interface  135  or the external device interface  130 . 
     In addition, the processor  330  may control the operation of the demultiplexer  310 , the video processor  320 , the OSD processor  340  of the signal processor, and the like. 
     The OSD processor  340  generates an OSD signal autonomously or according to user input. For example, the OSD processor  340  may generate signals by which various types of information are displayed as graphics or text on the display  180  according to a user input signal. The generated OSD signal may include various data such as a User Interface (UI), various menus, widgets, icons, etc. Further, the generated OSD signal may include a 2D object or a 3D object. 
     The OSD processor  340  may generate a pointer which can be displayed on the display according to a pointing signal received from the remote controller  200 . Particularly, such pointer may be generated by a pointing signal processor, and the OSD processor  340  may include such pointing signal processor (not shown). Alternatively, the pointing signal processor (not shown) may be provided separately from the OSD processor  340  without being included therein. 
     The mixer  345  may mix the OSD signal generated by the OSD processor  340  and the decoded video signal processed by the video processor  320 . The mixed video signal is provided to the frame rate converter  350 . 
     The frame rate converter (FRC)  350  may convert a frame rate of an input video. The frame rate converter  350  may output the input video as it is without converting the frame rate. 
     The formatter  360  may change the format of an input image signal into an image signal for displaying on the display  180  and output the changed image signal. 
     The formatter  360  may convert the format of a video signal. For example, the formatter  360  may convert the format of a 3D image signal into any one of various 3D formats, such as a side by side format, a top down format, a frame sequential format, an interlaced format, a checker box format, and the like. 
     The audio processor (not shown) in the signal processor may process the demultiplexed audio signal, or an audio signal of a predetermined content. To this end, the audio processor  370  may include various decoders. 
     Further, the audio processor (not shown) in the signal processor may also adjust the bass, treble, or volume of the audio signal. 
     A data processor (not shown) in the signal processor may process the demultiplexed data signal. For example, when the demultiplexed data signal is encoded, the data processor may decode the encoded demultiplexed data signal. Here, the encoded data signal may be Electronic Program Guide (EPG) information including broadcast information such as the start time and end time of a broadcast program which is broadcast through each channel. 
     The block diagram of the signal processor illustrated in  FIG.  4    is by example. The components of the block diagrams may be integrated or omitted, or a new component may be added according to the specifications of the signal processor. 
     Particularly, the frame rate converter  350  and the formatter  360  may not be included in the signal processor but may be provided individually, or may be provided separately as one module. 
       FIGS.  5 A to  5 B  are diagrams for explaining a static channel and a mobile channel. 
     First,  FIG.  5 A  illustrates an example in which an RF signal output from a base station TRS is received by a mobile terminal  100   b  of a pedestrian PES or is received by the mobile terminal  100   b  inside a vehicle VEC. 
     The mobile terminal  100   b  of the pedestrian PES may receive the RF signal through a static channel, and the mobile terminal  100   b  inside the vehicle VEC may receive the RF signal through a mobile channel. 
     (a) of  FIG.  5 B  is a diagram illustrating an example of a Doppler frequency signal SGa in a static channel. (b) of  FIG.  5 B  is a diagram illustrating an example of a Doppler frequency signal SGb in a mobile channel. 
     As shown in  FIG.  5 B , the frequency of the Doppler frequency signal SGb in the mobile channel is higher than the frequency of the Doppler frequency signal SGa in the static channel. 
     For example, when the moving speed of the pedestrian PES of  FIG.  5 A  is about 4 Km/h, the RF signal may correspond to the Doppler frequency signal SGa in the static channel as shown in (a) of  FIG.  5 B , and when the moving speed of the vehicle VEC of  FIG.  5 A  is about 80 Km/h, the RF signal may correspond to the Doppler frequency signal SGb in the mobile channel as shown in  FIG.  5 B . 
     Meanwhile, the mobile channel as a channel in which a channel state quickly changes in a wireless transmission channel may be a time-varying fading channel. 
       FIG.  6 A  is a diagram for explaining interpolation in the frequency domain and the time domain when an RF signal is an RF signal based on an orthogonal frequency division multiplexing (OFDM) method. 
     Referring to  FIG.  6 A , when a pilot signal is extracted from the RF signal, the pilot signal may be indicated in a pilot pattern in the frequency domain on the horizontal axis and the time domain on the vertical axis. 
     The signal processing device  520  may perform frequency interpolation in a horizontal direction and time interpolation in the vertical direction based on the pilot signal or the pilot pattern. 
     The signal processing device  520  may acquire an effective symbol or effective data in the RF signal based on this interpolation or the like. 
     The mobile channel detected by the signal processing device  520  may correspond to a channel that is changed over time due to the Doppler frequency (Doppler speed). 
     In this case, the channel is changed more over time as the Doppler frequency increases, and thus a channel change between symbols on the time axis in an OFDM symbol may be increased. 
     The signal processing device  520  may determine a channel change over time using a channel transfer function value of a pilot symbol positioned at an interval dy of the time axis in an OFDM symbol. 
       FIG.  6 B  is a diagram showing an example of time interpolation in a static channel. 
     Referring to  FIG.  6 B , the signal processing device  520  may restore a signal CVa corresponding to the static channel by performing time interpolation based on the pilot signal or the pilot pattern. 
       FIG.  6 C  is a diagram showing an example of time interpolation in a mobile channel. 
     Referring to  FIG.  6 C , the signal processing device  520  may restore a signal CVb corresponding to the mobile channel by performing time interpolation based on the pilot signal or the pilot pattern. 
     In this case, in the mobile channel, when time interpolation is performed, it may be difficult to restore an accurate signal, and accuracy may be remarkably lowered. Thus, in the mobile channel, time interpolation may not be performed. 
       FIG.  7    is a flowchart of a method of operating a signal processing device related to the present disclosure. 
     Referring to  FIG.  7   , the signal processing device  520  may extract a pilot signal based on a baseband signal (S 710 ). 
     In addition, the signal processing device  520  calculates the channel transfer function value based on the pilot signal (S 720 ). 
     For example, the signal processing device  520  may calculate frequency and time based channel transfer function values based on the pilot signal as illustrated in  FIG.  6 A . 
     Specifically, the signal processing device  520  may calculate subcarrier frequency based and symbol based channel transfer function values based on the pilot signal as illustrated in  FIG.  6 A . 
     Here, the channel transfer function value may be a Channel Transfer Function value or a CTF value. 
     Then, the signal processing device  520  calculates noise (S 730 ). 
     For example, the signal processing device  520  calculates noise by assuming that channel noise is additive white Gaussian noise (AWGN). 
     Then, the signal processing device  520  calculates channel state information (CSI) based on the calculated channel transfer function value and noise (S 740 ). In addition, the signal processing device  520  performs error correction based on the channel state information (S 750 ). 
     Equation 1 below is an equation showing a relationship between a received signal, and a channel and noise. 
         y=Hx+n    [Equation 1]
 
     Here, y as the received signal may be a baseband signal input into the signal processing device  520 . In addition, H may represent the channel transfer function, x may represent a transmitted signal, and n may represent channel noise. 
     According to  FIG.  7   , the signal processing device  520  utilizes Equation 2 below to calculate the channel state information. 
     
       
         
           
             
               
                 
                   CSI 
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     Here, H l,k  represents the channel transfer function, and σ as the channel noise represents the additive white Gaussian noise. 
     In this case, l represents an OFDM symbol index and k represents a subcarrier index. 
     That is, according to Equation 2, the channel state information is in proportion to a square of the channel transfer function value, and in inverse proportion to the square of the additive white Gaussian noise. 
     In addition, the signal processing device  520  performs the error correction based on the channel state information calculated by Equation 2. 
     However, an actual channel environment does not depend on the additive white Gaussian noise, and has a problem in that the performance deteriorates in a specific channel environment, e.g., impulsive interference or co-channel interference. 
     In particular, there is a problem in that performance deterioration by burst noise according to the impulse interference or narrow band noise according to the co-channel interference. 
     Therefore, the present disclosure a method that does not depend on the additive white Gaussian noise, and may reduce performance deterioration by burst noise or performance deterioration by narrow band noise in a specific channel environment, e.g., impulsive interference or co-channel interference. This will be described with reference to  FIG.  8    and below. 
       FIG.  8    is a flowchart of an operation of a signal processing device according to an embodiment of the present invention. 
     Referring to  FIG.  8   , the signal processing device  520  extracts the pilot signal based on the baseband signal (S 810 ). 
     In addition, the signal processing device  520  calculates the channel transfer function value based on the pilot signal (S 820 ). 
     For example, the signal processing device  520  may calculate frequency and time based channel transfer function values based on the pilot signal as illustrated in  FIG.  6 A . 
     Specifically, the signal processing device  520  may calculate subcarrier frequency based and symbol based channel transfer function values based on the pilot signal as illustrated in  FIG.  6 A . 
     Here, the channel transfer function value may be a Channel Transfer Function value or a CTF value. 
     Meanwhile, the channel transfer function may be expressed as H l,k , and in this case, l may represent an OFDM symbol index and k may represent the subcarrier index. 
     That is, the signal processing device  520  may calculate the channel transfer function values for each OFDM symbol index and for each subcarrier index. 
     Then, the signal processing device  520  calculates symbol based noise and carrier frequency based noise (S 830 ). 
     For example, the signal processing device  520  may calculate symbol based noise σ l  in relation to the burst noise according to the impulsive interference. In this case, l represents the OFDM symbol index. 
     As another example, the signal processing device  520  may calculate subcarrier frequency based noise σ k  in relation to the narrow band noise according to the co-channel interference. In this case, k represents the subcarrier index. 
     Then, the signal processing device  520  calculates the channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise (S 840 ). 
     In addition, the signal processing device  520  performs the error correction based on the calculated channel state information (S 850 ). 
     The signal processing device  520  may calculate the channel state information by using Equation 3 below. 
     
       
         
           
             
               
                 
                   CSI 
                   = 
                   
                     
                       E 
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                         σ 
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     Here, H l,k  represents the channel transfer function, σ l  represents the symbol based noise, and σ k  represents the subcarrier frequency based noise. 
     That is, the signal processing device  520  may calculate channel state information (CSI) which is in proportion to power σ 1   2  the channel transfer function H l,k , which is in inverse proportion to power σ l   2  of the symbol based noise σ l , and which is in inverse proportion to power σ l   2  of the subcarrier frequency based noise σ k . 
     As a result, when computing the channel state information (CSI), it is possible to accurately calculate the channel state information by considering contents regarding the burst noise and the narrow band noise. 
     Meanwhile, the signal processing device  520  performs the error correction based on the accurate channel state information to improve the performances for the burs noise and the narrow band noise. 
       FIG.  9 A  is a block diagram illustrating an RF signal receiving system according to an embodiment of the present disclosure. 
     Referring to  FIG.  9 A , the RF signal receiving system  10  according to an embodiment of the present disclosure may include the wireless signal transmitting device  10  for transmitting an RF signal CA, and the RF receiving device  80  for receiving the RF signal CA. 
     A noise signal, derived from a channel  70 , may be added to the RF signal CA transmitted by the wireless signal transmitting device  10 , and the wireless reception device  80  may receive the RF signal CA, to which the noise signal is added. 
       FIG.  9 B  is a block diagram illustrating an example of an RF receiving device according to an embodiment of the present disclosure. 
     Referring to  FIG.  9 B , the RF receiving device  80   a  according to an embodiment of the present disclosure may include the tuner module  110  for receiving an RF signal including noise of a channel and converting the RF signal into a baseband signal, and the signal processing device  520  for performing signal processing on the baseband signal. 
     In this case, the tuner module  110  may also function as a demodulator. Alternatively, the RF receiving device  80   a  may also function as the demodulator of  FIG.  2   . 
     The signal processor  520  according to an embodiment of the present disclosure may include the synchronizer  521 , the equalizer  523 , an error corrector  524 , and the like. 
     The synchronizer  521  may perform synchronization based on an input baseband signal. 
     The synchronizer  521  may perform synchronization based on a mean squared error (MSE). 
     For example, the synchronizer  521  may perform synchronization based on a mean squared error (MSE) and may perform synchronization again based on an updated mean squared error (MSE). 
     The signal processing device  520  may calculate an error e, which is a difference between the input baseband signal and a pilot signal, which is a reference signal, and may output a mean squared error (MSE) based on the calculated error e. 
     The equalizer  523  may perform equalization based on the signal synchronized by the synchronizer  521 . 
     The equalizer  523  may perform synchronization based on a mean squared error (MSE). 
     For example, the equalizer  523  may perform synchronization based on a mean squared error (MSE) and may perform synchronization again based on an updated mean squared error (MSE). 
     The equalizer  523  may perform channel equalization using channel information while performing equalization. 
     The equalizer  523  may perform interference estimation or channel estimation based on the signal synchronized by the synchronizer  521 . 
     The equalizer  523  may perform interference estimation or channel estimation based on a mean squared error (MSE). 
     For example, the equalizer  523  may perform interference estimation or channel estimation based on a mean squared error (MSE) and may perform interference estimation or channel estimation based on an updated mean squared error (MSE). 
     The equalizer  523  may estimate that a communication channel or a broadcast channel includes co-channel interference, adjacent-channel interference, single-frequency interference, burst noise, and phase noise. 
     The equalizer  523  may also estimate a communication channel or a broadcast channel as any one of a static channel, a mobile channel, and the like. 
     The static channel may include a Rayleigh channel, a Rician channel, and the like, and the mobile channel may include a vehicular channel, a Doppler channel, and the like. 
     The error corrector  524  may perform error correction based on the signal (equalization signal) equalized by the equalizer  523 . In particular, the error corrector  524  may perform forward error correction. 
     In this case, the mean squared error (MSE) may be performed based on the signal from the equalizer  523 . 
     The error corrector  524  may perform error correction based on the optimized mean squared error (MSE), thereby accurately performing error correction. 
     The error corrector  524  may accurately perform error correction even in the presence of interference related to burst noise. 
     Meanwhile, the error corrector  524  may accurately perform the error correction in spite of interference related to the narrow band noise. 
     The error corrector  524  may accurately perform error correction in consideration of that the communication channel is a static channel. 
     The error corrector  524  may accurately perform error correction in consideration of that the communication channel is a mobile channel. 
       FIG.  9 C  is a block diagram illustrating an example of an RF receiving device according to another embodiment of the present disclosure. 
     Referring to  FIG.  9 C , an RF receiving device  80   b  of  FIG.  9 C  may be similar to the wireless reception device  80  of  FIG.  9 B , but may be different therefrom in that the demodulator  120  is further included between the tuner module  110  and the signal processing device  520 . 
     The tuner module  110  of  FIG.  9 C  may receive an RF signal including noise from a channel and may convert the RF signal into an intermediate frequency signal, and the demodulator  120  may convert the intermediate frequency signal into a baseband signal. 
     The signal processing device  520  may perform signal processing on the baseband signal from the demodulator  120 , as described with reference to  FIG.  9 B . 
       FIG.  9 D  is an internal block diagram illustrating the signal processing device of  FIG.  9 B or  9 C . 
     Referring to  FIG.  9 D , the signal processing device  520  of  FIG.  9 B or  9 C  may receive a digital signal from an analog-digital-converter (ADC)  702 . Here, the digital signal may be a baseband signal. 
     The signal processing device  520  of  FIG.  9 B or  9 C  may include the synchronizer  521 , the equalizer  523 , and the error corrector  524 . 
     The synchronizer  521  may include a timing restorer  712  for performing timing recovery based on a received baseband signal, a prefix remover  714  for removing a cyclic prefix from the signal received from the timing restorer  712 , a Fourier transformer  716  for performing fast Fourier transform (FFT) on the signal received from the prefix remover  714 , and a guard band remover  718  for removing a guard band from the signal received from the Fourier transformer  716 . 
     The equalizer  523  may calculate a channel transfer function value, symbol based noise, and subcarrier frequency based noise based on the signal from the synchronizer  521 , and calculate channel state information based on the calculated channel transfer function value, symbol based noise, and subcarrier frequency based noise. 
     Meanwhile, the equalizer  523  may extract a pilot signal from the signal from the synchronizer  521 , and calculate the channel transfer function value based on the extracted pilot signal. As a result, performances for bust noise and narrow band noise may be improved. 
     Meanwhile, the equalizer  523  may extract the pilot signal from the signal from the synchronizer  521 , and calculate the symbol based noise and the subcarrier frequency based noise based on the extracted pilot signal. As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the equalizer  523  may calculate the symbol based noise and the subcarrier frequency based noise based on the signal from the synchronizer  521 . As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the equalizer  523  may calculate channel state information (CSI) which is in proportion to power of the channel transfer function value, which is in inverse proportion to power of the symbol based noise, and which is in inverse proportion to power of the subcarrier frequency based noise. As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the equalizer  523  may calculate a log-likelihood ratio based on the channel state information (CSI). As a result, the performances for the bust noise and the narrow band noise may be improved. 
     Meanwhile, the signal processing device  520  according to an embodiment of the present disclosure may further include an error corrector  524  performing error correction based on the channel state information (CSI). As a result, the performances for the bust noise and the narrow band noise may be improved. Further, data may be stably ensured. 
     Meanwhile, the erector corrector  524  may perform the error correction based on a mean squared error which increases as a level of the channel state information (CSI) decreases. As a result, the performances for the bust noise and the narrow band noise may be improved. Further, the data may be stably ensured. 
     Meanwhile, the equalizer  523  may extract a pilot signal from the signal from the synchronizer  521 , calculate a channel transfer function value of the extracted pilot signal, and selectively perform time interpolation based on the calculated channel transfer function value. As a result, the time interpolation may be selectively performed according to a channel. In particular, the data may be stably ensured even in the mobile channel environment. In addition, the channel estimation accuracy is improved. 
     To this end, the equalizer  523  may include a channel estimator  724  for extracting a pilot signal from the signal received from the synchronizer  521 , calculating the channel transfer function value of the extracted pilot signal, and performing channel estimation based on the calculated channel transfer function value, and an interpolator  722  for performing interpolation based on the calculated channel transfer function value. 
     The interpolator  722  may perform time interpolation and frequency interpolation based on the calculated channel transfer function value. 
     According to the present disclosure, the interpolator  722  may selectively perform time interpolation based on the calculated channel transfer function value. 
     The equalizer  523  may turn off time interpolation and may perform frequency interpolation when the difference in a channel transfer function value of a pilot signal between the previous subframe and the current subframe is equal to or greater than a threshold. Accordingly, in the case of a mobile channel, time interpolation may be turned off, and thus data may be stably ensured. 
     The equalizer  523  may perform time interpolation and frequency interpolation when a difference in a channel transfer function value of a pilot signal between the previous subframe and the current subframe is less than the threshold. Accordingly, in the case of a static channel but not a mobile channel, time interpolation and frequency interpolation may be performed, and thus data may be stably ensured. 
     The equalizer  523  may estimate a channel to be a mobile channel when a difference in a channel transfer function value of a pilot signal between the previous subframe and the current subframe is equal to or greater than the threshold. Accordingly, in the case of a mobile channel, time interpolation may be turned off, and thus data may be stably ensured. In addition, channel estimation accuracy may be improved. 
     The equalizer  523  may estimate a channel to be a static channel when a difference in a channel transfer function value of a pilot signal between the previous subframe and the current subframe is less than the threshold. Accordingly, in the case of a static channel, time interpolation and frequency interpolation may be performed, and data may be stably ensured. In addition, channel estimation accuracy may be improved. 
     The equalizer  523  may determine whether time interpolation is performed based on the calculated channel transfer function value, before time interpolation is performed. Thus, channel estimation accuracy may be improved, and as a result, data may be stably ensured. 
     The equalizer  523  may turn off time interpolation and may perform frequency interpolation in response to a difference between a representative value of a channel transfer function value of a pilot signal in the previous subframe and a representative value of a channel transfer function value of a pilot signal in the current subframe is equal to or greater than the threshold. Thus, time interpolation may be selectively performed based on the channel. In particular, data may also be stably ensured in a mobile channel environment. 
     The threshold may vary based on the moving speed or mode of the signal processing device  520 . Thus, time interpolation may be selectively performed based on the channel. In particular, data may also be stably ensured in a mobile channel environment. 
     The equalizer  523  may turn off time interpolation and may perform frequency interpolation from the next subframe when a difference in a channel transfer function value of a pilot signal between the previous subframe and the current subframe is equal to or greater than the threshold. Thus, time interpolation may be selectively performed based on the channel. In particular, data may also be stably ensured in a mobile channel environment. 
     The equalizer  523  may turn off time interpolation and may perform frequency interpolation from the current subframe when a difference in a channel transfer function value of a pilot signal between the previous subframe and the current subframe is equal to or greater than the threshold. Thus, time interpolation may be selectively performed based on the channel. In particular, data may also be stably ensured in a mobile channel environment. 
     The equalizer  523  may turn off time interpolation and may vary the time at which time interpolation is turned off based on the moving speed or mode of the signal processing device  520  when the difference in a channel transfer function value of a pilot signal between the previous subframe and the current subframe is equal to or greater than the threshold. Because the time at which time interpolation is turned off changes, data may be stably ensured adaptively to the moving speed or the mode. 
     When a first subframe and a second subframe in one frame have different transport formats, the equalizer  523  may perform control to make a threshold for the first subframe and a threshold for a second subframe different from each other. Data may be stably ensured by making thresholds different from each other according to transport formats. In addition, channel estimation accuracy may be improved. 
     The equalizer  523  may perform channel equalization using channel information after channel estimation or interpolation is performed. For example, the equalizer  523  may perform channel equalization in the time or frequency domain. 
     Then, the error corrector  524  may include a deinterleaver  732  for performing deinterleaving based on the signal of the equalizer  523 , a demapper  734  for performing demapping, and a channel decoder  736  for performing channel decoding. Thus, the error corrector  524  may perform forward error correction, and may finally output bit sequence data. 
     The signal processing device  520  may determine whether a channel is a mobile channel using a channel transfer function value of a pilot signal positioned along a pilot pattern before time interpolation is performed. 
     For example, the signal processing device  520  may calculate a difference in a channel transfer function value at the position of a pilot signal between the current symbol and the previous symbol, and may detect whether a channel is a mobile channel based on the calculated difference. 
     For example, in the case of a broadcast signal according to the ATSC 3.0 standard, a preamble, first/last sub frame boundary symbols (SBSs), and a data symbol have different pilot types and pilot patterns due to the structure of a frame, and thus the signal processing device  520  may use a scattered pilot of the data symbol. 
     In detail, the signal processing device  520  may calculate a difference in a channel transfer function value during one subframe section, and may determine whether a mobile channel is detected, based on the threshold. 
     The signal processing device  520  may turn off time interpolation in the case of a mobile channel. 
     In this case, the signal processing device  520  may turn off time interpolation in the next symbol based on the time at which the mobile channel is detected. 
     The signal processing device  520  may check information on whether a mobile channel of a previous frame is detected in a corresponding subframe of a next frame, and may turn on or off time interpolation. 
     The signal processing device  520  may perform control to selectively perform time interpolation base on a channel transfer function value, which rapidly changes over time. Thus, channel estimation accuracy may be improved. 
     In particular, the signal processing device  520  may detect whether a channel is a mobile channel using a signal before time interpolation and frequency interpolation are performed. Thus, the accuracy of detection of the mobile channel may be improved. 
     The signal processing device  520  may control the time at which time interpolation is turned off and may minimize delay in the time at which time interpolation is turned off. 
     The signal processing device  520  may determine whether a channel is a mobile channel based on a difference in a channel transfer function value at the position of a pilot signal between the current symbol and the previous symbol during one subframe section. 
     The signal processing device  520  may determine the channel to be a mobile channel and may turn off time interpolation when the difference in the channel transfer function value in one symbol section is equal to or greater than the threshold. 
     The signal processing device  520  may determine the channel to be a mobile channel and may determine a reference for turning off time interpolation according to the threshold. 
     For example, the signal processing device  520  may determine whether time interpolation is turned off by comparing the difference in the channel transfer function value in one symbol section with the threshold while increasing the Doppler frequency (Hz). 
     The signal processing device  520  may set the threshold at which to vary time interpolation to OFF from ON before the Doppler frequency becomes 10 to 20 Hz based on the time at which an error occurs due to the Doppler frequency (Hz). 
     Meanwhile, the mobile channel detected by the signal processing device  520  may correspond to a channel which is changed by a Doppler speed over time. 
       FIGS.  10 A to  12    are diagrams referenced for explaining an operation method of  FIG.  8   . 
     First,  FIG.  10 A  illustrates that the burst noise by the impulsive interference is generated. 
     OFDM symbols are sequentially received according to the time axis, but as illustrated in  FIG.  10 A , four pulses PSa, PSbm, PSc, and PSd may be generated due to the burst noise in symbol 0, symbol 1, etc. 
     In  FIG.  10 A , an interval between PSc and PSd as an interval of approximately Pm may be expressed by dozens of μsec (micro seconds) and a pulse width of PSd may be expressed by several n sec (nano seconds). 
     Meanwhile, an interval between first burst noise Ara and second burst noise Arb may be dozens of m sec (milliseconds). 
     While the burst noise is generated in  FIG.  10 A , when the channel state information (CSI) is calculated by using Equation 2, there is a problem in that inaccurate channel state information is calculated due to a time axis based error. 
     As a result, the signal processing device  520  in the present disclosure calculates the channel state information (CSI) by using Equation 3. 
     In particular, the symbol based noise σ l  is utilized instead of the additive white Gaussian noise of Equation 2 to calculate accurate channel state information even though the burst noise is generated. 
     Therefore, accurate error correction is possible even in error correction to improve the performance for the burst noise. 
     Then,  FIG.  10 B  illustrates that the narrow band noise by the co-channel interference is generated. 
     The channel transfer function is shown for each subcarrier frequency according to the frequency axis, but as illustrated in  FIG.  10 B , the narrow band noise may be generated around Hm,l, i.e., around a first subcarrier frequency. 
     While the narrow band noise is generated in  FIG.  10 B , when the channel state information (CSI) is calculated by using Equation 2, there is a problem in that inaccurate channel state information is calculated due to a frequency axis based error. 
     As a result, the signal processing device  520  in the present disclosure calculates the channel state information (CSI) by using Equation 3. 
     In particular, the subcarrier frequency based noise σ k  is utilized instead of the additive white Gaussian noise of Equation 2 to calculate accurate channel state information even though the narrow band noise is generated. 
     Therefore, accurate error correction is possible even in error correction to improve the performance for the narrow band noise. 
     Consequently, the signal processing device  520  may calculate channel state information (CSI) which is in proportion to power σ l   2  of the channel transfer function H l,k , which is in inverse proportion to power σ l   2  of the symbol based noise σ l , and which is in inverse proportion to power σ l   2  of the subcarrier frequency based noise σ k  according to Equation 3. 
     As a result, when computing the channel state information (CSI), it is possible to accurately calculate the channel state information by considering contents regarding the burst noise and the narrow band noise. 
     Meanwhile, the signal processing device  520  performs the error correction based on the accurate channel state information to improve the performances for the burs noise and the narrow band noise. 
       FIG.  11    is a diagram illustrating the channel transfer function value when the burst noise and the narrow band noise in  FIGS.  10 A and  10 B  are not present. 
     The signal processing device  520  may calculate channel state information (CSI) which is in proportion to the power σ l   2  of the channel transfer function H l,k , which is in inverse proportion to the power σ l   2  of the symbol based noise σ l , and which is in inverse proportion to the power σ l   2  of the subcarrier frequency based noise σ k  according to Equation 3. 
     As a result, accurate channel state information computation is possible by considering various channel environments. 
     When the first subframe and the second subframe in one frame have different transport formats, the equalizer  523  in the signal processing device  520  may perform control to make the threshold for the first subframe and the threshold for the second subframe different from each other. 
     By varying the threshold based on transport formats, a reference for the mobile channel may be changed, and as a result, the time at which time interpolation is turned off may be changed. As a result, data may be stably ensured. In addition, channel estimation accuracy may be improved. 
     For example, in the case of FFT=32 K and QAM=64 in the first subframe, the equalizer  523  in the signal processing device  520  may set the threshold for the first subframe to correspond to a difference in a channel transfer function value at a Doppler frequency of 30 Hz. 
     In another example, in the case of FFT=8 K and QAM=QPSK in the second subframe, the equalizer  523  in the signal processing device  520  may set the threshold for the second subframe to correspond to a difference in a channel transfer function value at a Doppler frequency of 50 Hz. 
     In another example, in the case of FFT=16 K and QAM=256 in the third subframe, the equalizer  523  in the signal processing device  520  may set the threshold for the third subframe to correspond to a difference in a channel transfer function value at a Doppler frequency of 10 Hz. 
     The equalizer  523  in the signal processing device  520  may lower the threshold as the computational load of Fourier transform is increased. 
     The equalizer  523  in the signal processing device  520  may lower the threshold as the amount of data of a modulation method is increased. 
     The equalizer  523  in the signal processing device  520  may lower the threshold as the moving speed of the signal processing device  520  is increased. 
     The equalizer  523  in the signal processing device  520  may set the time at which time interpolation is turned off to be earlier as a computational load of Fourier transform is increased. 
     The equalizer  523  in the signal processing device  520  may set the time at which time interpolation is turned off to be earlier as the amount of data of a modulation method is increased. 
     Meanwhile, the equalizer  523  in the signal processing device  520  may set an off time of the time interpolation to be earlier as a moving speed of the signal processing device  520  increases. 
       FIG.  12    is a set of diagrams showing an example of a broadcasting image based on whether time interpolation is ON or OFF in a static channel and a mobile channel. 
       FIG.  12 A  shows an example of a broadcasting image  510  displayed on the display  180  of the image display apparatus  100  when time interpolation in a static channel is turned on as shown in (a) of  FIG.  5 B . 
     As described above, even if time interpolation in a static channel is performed, broadcast signal data may be stably ensured, and thus the broadcasting image  510  may be clearly displayed. 
       FIG.  12 B  shows an example of a broadcasting image  511  displayed on the display  180  of the image display apparatus  100  when time interpolation in a mobile channel is turned on, as shown in (b) of  FIG.  5 B . 
     As described above, when time interpolation in a mobile channel is performed, the accuracy of time interpolation may be remarkably degraded, and thus the accuracy of broadcast signal data may be degraded, and accordingly, a defective image  511  may be displayed as shown in the drawing. 
       FIG.  12 C  illustrates the broadcasting image  520  displayed in the display  180  of the image display apparatus  100  when the time interpolation in the mobile channel illustrated in (b) of  FIG.  5 B  is turned off. 
     As described above, when the time interpolation in the mobile channel is turned off, it is possible to ensure stable broadcasting signal data, so a vivid broadcasting image  520  may be displayed. 
       FIG.  12 B  may also be a broadcasting image  511  displayed in the display  180  of the image display apparatus  100  when the burst noise or the narrow band noise is generated while the channel state information computation by Equation 2 is performed. 
     As described above, when the burst noise or the narrow band noise is generated while the channel state information computation by Equation 2 is performed, the computation of the channel state information is inaccurate, so a defective image  511  may be displayed as illustrated in  FIG.  12 B . 
       FIG.  12 C  illustrates a broadcasting image  520  displayed in the display  180  of the image display apparatus  100  when the burst noise or the narrow band noise is generated while the channel state information computation by Equation 3 is performed. 
     As described above, even though the burst noise or the narrow band noise is generated while the channel state information computation by Equation 3 is performed, the computation of the channel state information is accurate, so a vivid broadcasting image  520  with no defect may be displayed as illustrated in  FIG.  12 C . 
     Operations performed by a signal processing device or an image display apparatus according to the present disclosure may be embodied as processor-readable code on a processor-readable recording medium. The processor-readable recording medium may include any data storage device that is capable of storing programs or data which is capable of being thereafter read by a processor. The processor-readable recording medium may also be distributed over network coupled calculator systems so that the calculator readable code is stored and executed in a distributed fashion. 
     While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present disclosure. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the subject matter and scope of the present disclosure. 
     The present disclosure is applicable to the signaling processing device and the image display apparatus including the same.