Receiver, receiving system, receiving method and program

Abstract

To accurately extract and remove pulse noise from a received signal.SOLUTION: A receiver generates a first noise signal by calculating the difference between a guard interval added to the beginning of a data interval of a modulated signal and a guard-equivalent interval at the end of the data interval from which the guard interval is copied. The receiver then adjusts filter parameters to minimize the difference between the signal in the guard interval or the signal in the guard-equivalent interval and the second noise signal. The receiver then removes pulse noise included in the data interval from the second noise signal generated using the adjusted filter parameters as a noise replica signal.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a receiver, a receiving system, a receiving method, and a program. [Background technology]

[0002] Patent Document 1 listed below describes detecting and suppressing noise components present in null portions (no-signal portions) of a demodulated OFDM signal as noise components contained in a signal of a subcarrier frequency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-341241 Summary of the Invention [Problem to be solved by the invention]

[0004] To remove pulse noise contained in a received wireless signal, such as an OFDM signal, it is desirable to accurately determine the occurrence time (position on the time axis) and period of the pulse noise along the time axis in the received signal. However, conventional techniques determine noise components present in null portions (no-signal portions) of an OFDM signal, but do not determine the occurrence time and period of the pulse noise in the received signal. For example, in a received signal before demodulation, signal components are superimposed on the pulse noise. This makes it difficult to accurately determine the occurrence time and period of the pulse noise. An aspect of the disclosed embodiment is to accurately extract and remove pulse noise from a received signal. [Means for solving the problem]

[0005] The disclosed embodiment is exemplified by a receiver. The receiver generates a first noise signal by calculating the difference between a guard interval added to the beginning of a data interval of a modulated signal and a guard-equivalent interval at the end of the data interval from which the guard interval is copied. The receiver then processes the first noise signal using an adaptive filter to generate a second noise signal. The adaptive filter adjusts filter parameters to minimize the difference between the second noise signal and the signal in the guard interval or the guard-equivalent interval. The receiver then removes pulse noise included in the data interval from the second noise signal generated using the adjusted filter parameters as a noise replica signal. [Effects of the Invention]

[0006] In this way, the receiver generates the first noise signal by calculating the difference between the guard interval added to the beginning of the data section of the modulated signal and the guard-equivalent interval at the end of the data section from which the guard interval was copied. Because the guard interval and the guard-equivalent interval contain the same signal components, the receiver can properly acquire the first noise signal.

[0007] Furthermore, the receiver generates a second noise signal from the first noise signal using an adaptive filter that adjusts filter parameters to minimize the difference between the guard interval signal or the guard-equivalent interval signal and the generated second noise signal. The adaptive filter can adjust filter parameters (filter coefficients) to minimize the difference. Therefore, the receiver can generate a desired second noise signal that minimizes the difference between the guard interval signal or the guard-equivalent interval signal and the generated second noise signal.

[0008] Then, the receiver detects a second noise generated by the adjusted filter parameters. Since the signal is used as a noise replica signal to remove the pulse noise contained in the data section, the pulse noise can be removed based on the desired second noise signal. In other words, this receiver can accurately extract and remove pulse noise from the received signal. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of a hardware configuration of a receiving system. [Figure 2] FIG. 2 is a diagram illustrating a detailed configuration of the RF circuit. [Figure 3] FIG. 3 is a diagram illustrating a detailed configuration of the noise removal circuit. [Figure 4] FIG. 4 is a diagram illustrating a detailed configuration of the pulse noise detection unit. [Figure 5] FIG. 5 is a diagram illustrating a detailed configuration of the noise generating unit. [Figure 6] FIG. 6 is a sequence diagram illustrating a receiving process of the noise removal circuit. [Figure 7] FIG. 7 is a diagram illustrating a detailed configuration of a pulse noise detection unit according to the first modification. [Figure 8] FIG. 8 is a sequence diagram illustrating a receiving process of the noise removal circuit according to the second modification. [Figure 9] FIG. 10 is a diagram illustrating a simulation result. [Figure 10] FIG. 10 is a diagram illustrating a simulation result. [Figure 11] FIG. 10 is a diagram illustrating a simulation result. [Figure 12] FIG. 10 is a diagram illustrating a simulation result. DETAILED DESCRIPTION OF THE INVENTION

[0010] A receiving system 10, a broadcast receiving unit 16 as a broadcast receiver, a receiving method, and a program according to one embodiment will be described below with reference to the drawings. In this embodiment, the receiving system 10 is exemplified by a digital television, a digital radio, or an in-vehicle device equipped with these. The in-vehicle device may be, for example, a head unit having audio, visual, and navigation functions.

[0011] <Embodiment> (Configuration) 1 is a diagram illustrating an example of the hardware configuration of a receiving system 10. The receiving system 10 has a CPU 11, a main memory unit 12, and external devices connected via an interface (I / F), and executes information processing such as output of broadcast content using a computer program.

[0012] The CPU 11 executes a computer program that has been loaded in an executable manner into the main memory unit 12, thereby providing the functions of the receiving system 10. The main memory unit 12 is also referred to simply as a memory, and stores the computer program executed by the CPU 11, the data processed by the CPU 11, and the like. The CPU 11 is also referred to as a processor. However, the CPU 11 is not limited to a single processor, and may have a multi-processor configuration. Furthermore, the CPU 11 may be a single processor connected via a single socket, and may have a multi-core configuration.

[0013] Furthermore, the CPU 11 may include a plurality of different types of processors. For example, at least a portion of the processing of the receiving system 10 may be provided by a dedicated processor such as a Digital Signal Processor (DSP), a Graphics Processing Unit (GPU), a numerical processor, a vector processor, or an image processor, or an Application Specific Integrated Circuit (ASIC). Furthermore, at least a part of the receiving system 10 may be a dedicated large scale integration (LSI) such as a field-programmable gate array (FPGA) or other digital circuit. At least a portion of the receiving system 10 may include analog circuits.

[0014] The main memory unit 12 is connected to the CPU 11 via an internal bus. The main memory unit 12 includes a dynamic random access memory (DRAM), a static random access memory (SRAM), a read / write memory (WRITE), a read / write d Only Memory (ROM), etc. The CPU 11, the main memory unit 12, and the interface (I / F) etc. are called the control unit.

[0015] Examples of external devices include an external storage unit 13, a display unit 14, an operation unit 15, and a broadcast receiving unit 16. The external devices do not have to be integrated with the control unit (CPU 11, main storage unit 12, etc.). Each of the external devices may be connected to the housing of the receiving system 10 via an interface (I / F) or the like.

[0016] The external storage unit 13 is used, for example, as a storage area that supplements the main storage unit 12, and stores computer programs executed by the CPU 11, data processed by the CPU 11, etc. The external storage unit 13 is a hard disk drive, a solid state drive (SSD), etc. Furthermore, the receiving system 10 may be provided with a drive device for a removable storage medium, such as a Blu-ray disc, a Digital Versatile Disc (DVD), a Compact Disc (CD), or a flash memory card.

[0017] The display unit 14 is, for example, a liquid crystal display, an electroluminescence panel, an organic light emitting diode (OLED), etc. The operation unit 15 is, for example, an array of push buttons, a keyboard, a pointing device, etc. In this embodiment, a touch panel is exemplified as the pointing device.

[0018] The broadcast receiving unit 16 receives broadcast waves distributed as radio signals modulated by Orthogonal Frequency Division Multiplexing (OFDM), for example, and outputs broadcast content such as sound. In FIG. 1, the broadcast receiving unit 16 receives radio signals from the antenna 1 and outputs sound from the speaker 5. However, the broadcast receiving unit 16 may also output video to the display unit 14. The speaker 5 and the display unit 14 are examples of output devices.

[0019] The broadcast receiving unit 16 includes a Radio Frequency (RF) circuit 2, a baseband circuit 3, and an amplifier. The broadcast receiving unit 16 has an amplifier 4. The broadcast receiving unit 16 may be a single-chip semiconductor device. The broadcast receiving unit 16 may also be a combination of multiple semiconductor devices. For example, the RF circuit 2 may be a single-chip semiconductor device. The baseband circuit 3 and the amplifier 4 may also be a single semiconductor device. Furthermore, the baseband circuit 3 and the amplifier 4 may each be separate semiconductor devices. The components of the broadcast receiving unit 16 are basically hardware circuits. However, the broadcast receiving unit 16 may have a processor such as a CPU, GPU, or DSP, and a memory, and may perform processing as at least some of the components of the broadcast receiving unit 16 according to a computer program.

[0020] The RF circuit 2 demodulates, for example, a radio signal modulated by OFDM (modulated signal), and inputs a baseband signal of digital data to the baseband circuit 3.

[0021] The baseband circuit 3 reproduces, for example, sound from the baseband signal demodulated by the RF circuit 2 and inputs the sound to the amplifier 4. The amplifier 4 amplifies the reproduced sound and drives a speaker 5. However, the baseband circuit 3 may also reproduce video from the baseband signal demodulated by the RF circuit 2 and output the video to a display unit 14 via, for example, a graphics processing unit or the like.

[0022] 2 is a diagram illustrating a detailed configuration of the RF circuit 2. The RF circuit 2 has an amplifier circuit 21, a noise elimination circuit 22, and a demodulation circuit 23. The amplifier circuit 21 amplifies the radio signal received by the antenna 1 and inputs the amplified signal to the noise elimination circuit 22.

[0023] The noise removal circuit 22 extracts pulse noise from the signal amplified by the amplifier circuit 21, and removes the pulse noise from the amplified signal using the extracted pulse noise. The demodulation circuit 23 demodulates the signal from which the pulse noise has been removed into a baseband signal carried by a wireless signal. The demodulation circuit 23 demodulates the baseband signal from, for example, a signal modulated by OFDM. The demodulated baseband signal is input to the baseband circuit 3.

[0024] 3 is a diagram illustrating a detailed configuration of the noise removal circuit 22. The noise removal circuit 22 has a symbol synchronization unit 221, a guard interval extraction unit 222, a guard-equivalent interval extraction unit 223, a pulse noise detection unit 224, a noise generation unit 225, an adaptive filter (ADF) 226, and a subtractor 227.

[0025] The symbol synchronization unit 221 detects the start of an OFDM symbol in the received signal. An OFDM symbol has a guard interval added to the beginning of a data interval (called a symbol interval) of the modulated signal to be demodulated. If the length (time) of the guard interval is Tg and the length (time) of the symbol interval is Te, the modulated signal to which the guard interval has been added has a time width of Tg+Te, including the symbol interval and guard interval. The guard interval is also called a cyclic prefix.

[0026] The signal in the guard interval is a copy of the signal in a partial interval (length Tg) at the end of the symbol. This partial interval (length Tg) is the source of the signal in the guard interval (length Tg). This partial interval (length Tg) can be called a guard-equivalent interval. Therefore, for example, by calculating the correlation between received signal R(t) and signal R(t+Ts) shifted by one symbol interval (Ts), symbol synchronization unit 221 can detect the division of the OFDM symbol, for example, the start position (timing) of the symbol, as the peak position of the correlation.

[0027] The guard interval extractor 222 extracts the guard interval preceding the start position of the symbol detected by the symbol synchronizer 221. That is, the guard interval extractor 222 retrieves a signal of the guard interval length (Tg) going back along the time axis from the start position of the symbol.

[0028] The guard-equivalent interval extractor 223 acquires the signal copied to the guard interval from the end of the symbol interval. In this embodiment, the signal at the end of the symbol interval that has been copied to the guard interval is called a guard-equivalent interval. The guard-equivalent interval extractor 223 retrieves the signal for the guard interval length (Tg) by tracing back along the time axis from the end of the symbol.

[0029] The pulse noise detector 224 detects at least one of the occurrence position (time) of pulse noise in the guard interval and the occurrence time interval of pulse noise based on the signal in the OFDM guard interval and symbol interval. Details of the pulse noise detector 224 are illustrated in FIG.

[0030] The noise generator 225 extends the occurrence position of the pulse noise in the guard interval detected by the pulse noise detector 224 to the entire symbol interval, and generates a noise replica signal NR(t). Details of the noise generator 225 are illustrated in FIG.

[0031] The adaptive filter 226 removes pulse noise from the symbol interval of the received signal R(t) based on the noise replica signal NR(t) generated by the noise generator 225. The adaptive filter 226 adjusts the amplitude and phase of the noise replica signal NR(t), which is the input signal, so that the feedback signal F(t) approaches a minimum, and generates the output signal O(t).

[0032] More specifically, the adaptive filter 226 incorporates an adaptive algorithm, and adjusts the filter coefficients (also called filter parameters) in accordance with this adaptive algorithm so that the signal F(t) approaches a minimum. Various methods have been proposed as such adaptive algorithms (for example, JP-A-11-259078, Isao Nakanishi, Institute of Electronics, Information and Communication Engineers, Forest of Knowledge, Group 1, Chapter 3 (https: / / www.ieice-hbkb.org / See files / 01 / 01gun_09hen_03m.pdf (accessed March 22, 2024).

[0033] The subtractor 227 generates a difference value R(t)-O(t) between the received signal R(t) and the output signal O(t) of the adaptive filter 226, and feeds this difference value R(t)-O(t) back to the adaptive filter 226 as a signal F(t). The received signal R(t) includes a signal component and a pulse noise component. The adaptive filter 226 adjusts the amplitude and phase of the noise replica signal NR(t) by changing the filter coefficients. The adaptive filter 226 then acts to make the output signal O(t) approach the pulse noise contained in the received signal R(t). As a result of the action of the adaptive filter 226, the feedback signal F(t) approaches the minimum signal value (i.e., the signal component or energy from which the pulse noise has been reduced), and the pulse noise is removed or suppressed from the symbol interval of the received signal R(t).

[0034] 4 is a diagram illustrating a detailed configuration of pulse noise detection unit 224. Pulse noise detection unit 224 has two subtractors 2241 and 2243, and adaptive filter 2242. Here, of received signal R(t), the signal in the guard interval is taken to be S1+N1. Here, S1 is a signal component and N1 is pulse noise. Also, the signal in the guard-equivalent interval is taken to be S2+N2. Here, S2 is a signal component and N2 is pulse noise. Note that S1 and S2 are the same signal.

[0035] 4, the pulse noise detection unit 224 generates a difference value between the signal in the guard interval (S1+N1) and the signal in the guard-equivalent interval (S2+N2) using the subtractor 2241. Since S1 and S2 are the same signal, the difference value is, for example, N1-N2, which is an example of a first noise signal.

[0036] Meanwhile, pulse noise detection unit 224 generates a difference value S1+N1-O(t) between the guard interval signal (S1+N1) and the output signal of adaptive filter 2242 using subtractor 2243, and feeds this back as signal F(t) to adaptive filter 2242. Similar to adaptive filter 226 described in Fig. 3, adaptive filter 2242 adjusts the filter coefficients so that the fed-back signal F(t) is minimized, and generates output signal O(t) from input signal N1-N2.

[0037] 4, the adaptive filter 2242 sets the input signal N1-N2 to a signal N1' that is close to the noise N1 in the guard interval, thereby bringing the fed-back signal F(t) closer to the minimum (signal component S1). Therefore, the pulse noise detection unit 224 outputs the signal N1' that is close to the noise N1 in the guard interval as the output signal O(t). The signal N1' is an example of a second noise signal.

[0038] 5 is a diagram illustrating a detailed configuration of the noise generation unit 225. The noise generation unit 225 generates a noise replica signal NR(t) that exists throughout the entire symbol interval based on the signal N1′ detected by the pulse noise detection unit 224. The noise generation unit 225 has a repetition unit 2251, a cross-correlation unit 2252, and a zero data insertion unit 2253.

[0039] The repeater 2251 repeats and connects a signal N1' detected by the pulse noise detector 224 that is similar to noise N1 and has the length (Tg) of the guard interval to generate a signal with the length (Te) of the entire symbol interval. In other words, the repeater 2251 repeatedly copies the signal N1' while shifting it by the length (Tg) of the guard interval, and extends it to the entire symbol interval. This signal for the entire symbol interval is designated N'(t).

[0040] The cross-correlation unit 2252 receives the input, i.e., the symbol detected by the symbol synchronization unit 221 in FIG. The cross-correlation between the received signal R(t) in the symbol interval and the signal N'(t) for the entire symbol interval is generated. The zero data insertion unit 2253 then identifies the position within the symbol interval at which the cross-correlation output by the cross-correlation unit 2252 reaches a peak. The zero data insertion unit 2253 then inserts zeros (zero data) from the beginning of the symbol interval to the position at which the cross-correlation peaks. Furthermore, the zero data insertion unit 2253 inserts the signal N'(t) for the entire symbol interval into the interval after the position at which the peak occurs, thereby generating a noise replica signal NR(t).

[0041] That is, the cross-correlation unit 2252 and the zero data insertion unit 2253 shift the signal N'(t) to the position within the symbol interval where the cross-correlation between the received signal R(t) in the symbol interval and the signal N'(t) for the entire symbol interval reaches a peak. The zero data insertion unit 2253 then inserts zeros into the leading portions of the symbols that become blank as a result of the shift, thereby completing the symbols. This generates the noise replica signal NR(t). Shifting the signal N'(t) to the position within the symbol interval where the cross-correlation reaches a peak is an example of matching the relative positions of the symbol interval, which is an example of a data interval, and the noise replica signal NR(t).

[0042] (Processing sequence) 6 is a sequence diagram illustrating the reception process of the noise removal circuit 22 of this embodiment. In this process, the noise removal circuit 22 performs symbol synchronization with the received signal amplified by the amplifier circuit 21 (S1). Then, the noise removal circuit 22 detects the occurrence time of pulse noise in the guard interval using the pulse noise detection unit 224, and generates a signal N1' that is similar to the noise N1 (S2).

[0043] Next, the noise elimination circuit 22 generates a noise replica signal NR(t) using the noise generator 225 (S3). Then, the noise elimination circuit 22 removes or suppresses the noise replica signal NR(t) from the received signal R(t) in the symbol interval using the adaptive filter 226 and the subtractor 227 (S4).

[0044] The noise elimination circuit 22 inputs the received signal R(t) of the symbol interval from which the noise replica signal NR(t) has been eliminated or suppressed to the demodulation circuit 23. The noise elimination circuit 22 repeats the above process for each symbol interval.

[0045] Although the above is processing by a hardware circuit, the RF circuit 2 may have a processor such as a CPU, GPU or DSP and a memory, and the processor may execute at least part of the processing in FIG. 6 by a computer program on the memory.

[0046] (Modification 1 of the embodiment) 4, the first noise signal (N1-N2) is generated by subtracting the signal (S2+N2) in the guard-equivalent interval from the signal (S1+N1) in the guard interval. Furthermore, the second noise signal (N1') is generated from the signal (S1+N1) in the guard interval and the first noise signal (N1-N2). The noise replica signal NR(t) is then generated from the second noise signal (N1'). However, the processing of the noise removal circuit 22 is not limited to this.

[0047] 7 is a diagram illustrating a detailed configuration of a pulse noise detection unit 224A according to Modification 1. In FIG. 7, the relationship between the signal (S1+N1) in the guard interval and the signal (S2+N2) in the guard-equivalent interval is reversed compared to FIG. 4. That is, in FIG. 7, the signal (S1+N1) in the guard interval is subtracted from the signal (S2+N2) in the guard-equivalent interval to generate a first noise signal (N2-N1). Furthermore, a second noise signal (N2') is generated from the signal (S2+N2) in the guard-equivalent interval and the first noise signal (N2-N1). Then, the noise generation unit 225 in FIG. 5 generates a noise replica signal (N2') from the second noise signal (N2'). That is, a noise replica signal NR(t) is generated by a second noise signal (N2') that is close to the noise N2 in the guard-equivalent section at the end of the symbol section, and the noise in the symbol section may be removed.

[0048] In this embodiment, the second noise signal (N1' or N2') is individually referred to as a third noise signal (N1') and a fourth noise signal (N2') (see Variation 2 below).

[0049] (Effects of the embodiment) As described above, the RF circuit 2 (noise removal circuit 22) of the receiving system 10 calculates the difference between the guard interval added to the beginning of the data interval (symbol interval) of the modulated signal and the guard-equivalent interval at the end of the data interval (symbol interval) from which the guard interval is copied. The receiving system 10 generates a first noise signal (N1-N2 or N2-N1) through this difference calculation. The RF circuit 2 then operates the adaptive filter 2242 to minimize the difference between the signal in the guard interval (S1+N1) or the signal in the guard-equivalent interval (S2+N2) and the generated second noise signal (N1' or N2'). In other words, the RF circuit 2 adjusts the filter parameters of the adaptive filter 2242 to minimize the difference.

[0050] Then, the RF circuit 2 processes the first noise signal (N1-N2 or N2-N1) using the adaptive filter 2242 whose filter parameters have been adjusted in this manner to generate a second noise signal (N1' or N2'). Furthermore, the RF circuit 2 generates a noise replica signal (NR(t)) based on the second noise signal (N1' or N2') and removes pulse noise contained in the data interval (symbol interval). In this way, the receiving system 10 can obtain information on the occurrence time or occurrence time interval of pulse noise using signals in the guard interval and the guard-equivalent interval. As a result, the receiving system 10 can accurately generate the noise replica signal (NR(t)). Furthermore, the receiving system 10 can adjust the filter coefficients by the action of the adaptive filter 226 and remove pulse noise in accordance with fluctuations in the amplitude and phase of the received signal.

[0051] Furthermore, the RF circuit 2 generates a noise replica signal (NR(t)) of the length (Te) of the entire data section (symbol section) by repeatedly arranging the second noise signal (N1' or N2'), thereby enabling the noise replica signal (NR(t)) to be generated with high accuracy.

[0052] Furthermore, the RF circuit 2 shifts the position of the noise replica signal (NR(t)) on the time axis in accordance with the peak position of the cross-correlation between the generated noise replica signal (NR(t)) of the entire length of the data interval (symbol interval) and the data interval (symbol interval).The receiving system 10 then aligns the relative positions of the data interval (symbol interval) and the noise replica signal (NR(t)), thereby reducing the deviation between the noise and the noise replica signal and enabling efficient removal of pulse noise.

[0053] Furthermore, the RF circuit 2 interpolates zero data into partial intervals on the time axis corresponding to the data interval (symbol interval) where the noise replica signal does not exist, which are generated by shifting the noise replica signal (NR(t)). As a result, the receiving system 10 can obtain an appropriate noise replica signal (NR(t)) that does not have a time interval where an indeterminate value exists.

[0054] (Modification 2 of the embodiment) In the above embodiment, the RF circuit 2 repeatedly arranges the second noise signal (N1' or N2') to generate a noise replica signal (NR(t)) having the length (Te) of the entire data section (symbol section), which is a symbol section, as shown in FIGS. 4 to 7. However, in the receiving system 10 However, the processing of the RF circuit 2 and the noise removal circuit 22 is not limited to the above processing. Hereinafter, in this Modification 2, the second noise signal (N1' or N2') will be individually referred to as a third noise signal (N1') and a fourth noise signal (N2'), respectively.

[0055] 8 is a sequence diagram illustrating a receiving process of the noise elimination circuit 22 according to the second modification. In this process, the noise elimination circuit 22 divides the symbol interval into a first half and a second half. Then, in the first half of the symbol interval, the noise elimination circuit 22 generates a noise replica signal (NR1(t)) based on a third noise signal (N1'). It can be said that the noise replica signal (NR1(t)) in the first half of the symbol interval is based on the noise N1 in the guard interval.

[0056] Furthermore, the noise removal circuit 22 generates a noise replica signal (NR2(t)) based on the fourth noise signal (N2') in the latter half of the symbol interval. The noise replica signal (NR2(t)) in the latter half of the symbol interval can be said to be based on the noise N2 in the guard-equivalent interval.

[0057] In Fig. 8, the symbol synchronization of S1 is the same as in Fig. 6. Then, for the first half of the symbol interval, the noise removal circuit 22 generates a third noise signal (N1') including the pulse noise occurrence time in the guard interval using the pulse noise detection unit 224 (Fig. 4). Also, for the second half of the symbol interval, the noise removal circuit 22 detects a fourth noise signal (N2') including the pulse noise occurrence time in the guard-equivalent interval using the pulse noise detection unit 224A (Fig. 7) (S2A).

[0058] The noise elimination circuit 22 then repeatedly arranges the third noise signal (N1') including the pulse noise occurrence time in the guard interval over the length of the first half of the symbol interval to generate a noise replica signal (NR1(t)) for the first half of the symbol interval. The noise elimination circuit 22 also repeatedly arranges the fourth noise signal (N2') including the pulse noise occurrence time in the guard equivalent interval over the length of the second half of the symbol interval to generate a noise replica signal (NR2(t)) for the second half of the symbol interval.

[0059] The noise reduction circuit 22 then generates a noise replica signal NR(t) for the entire symbol from the noise replica signal (NR1(t)) for the first half of the symbol interval and the noise replica signal (NR2(t)) for the second half of the symbol interval (S3A). The noise replica signal NR(t) is obtained by combining the noise replica signal (NR1(t)) for the first half of the symbol interval and the noise replica signal (NR2(t)) for the second half of the symbol interval with a time axis shift. The noise reduction circuit 22 removes pulse noise from the received signal using the noise replica signal NR(t) generated as described above (S4). The subsequent processing is the same as in FIG. 6. The processing of S4 is an example of removing pulse noise using the noise replica signal (NR1(t)) generated from the signal in the guard interval in the first half of the data interval and the noise replica signal (NR2(t)) generated from the signal in the guard-equivalent interval in the second half of the data interval.

[0060] As described above, the RF circuit 2 generates the third noise signal (N1') for the first half of the data interval (symbol interval). That is, the RF circuit 2 processes the first noise signal (N1-N2) using the adaptive filter 2242 that minimizes the difference between the signal (S1+N1) in the guard interval and the generated third noise signal (N1') to generate the third noise signal (N1'). Furthermore, the receiving system 10 generates a fourth noise signal (N2') for the second half of the data interval (symbol interval). That is, the RF circuit 2 processes the first noise signal (N2-N1) using the adaptive filter 2242 that minimizes the difference between the signal (S2+N2) in the guard-equivalent interval and the generated fourth noise signal (N2') to generate the fourth noise signal ( Furthermore, the receiving system 10 generates a noise replica signal (NR1(t)) using the third noise signal (N1') in the first half of the data period (symbol period), and generates the noise replica signal (NR2(t)) using the fourth noise signal (N2') in the second half of the data period (symbol period).

[0061] The noise replica signal (NR1(t)) in the first half of the data interval (symbol interval) is a signal based on noise N1 in the guard interval added to the beginning of the symbol interval. Moreover, the noise replica signal (NR2(t)) in the second half of the data interval (symbol interval) is a signal based on noise N2 in the guard-equivalent interval at the end of the symbol interval. Therefore, compared to the processes in Figures 4 to 7, this process generates a noise replica signal NR(t) for the entire symbol interval based on closer intervals. That is, the first half of the symbol interval is adjacent to the guard interval, and the second half of the symbol interval is adjacent to the guard-equivalent interval. Therefore, a more desirable noise replica signal (NR(t)) is generated.

[0062] (Processing example) Processing examples are shown in Figures 9 to 12. Figures 9 to 12 illustrate simulation results of processing a signal in which pseudo noise is added to a pseudo signal. In Figures 9 to 12, the horizontal axis represents the time axis, and the vertical axis represents the power of the signal including noise. However, both the time axis and the signal power are unitless. Note that signal amplitude may be used instead of signal power.

[0063] Fig. 9(A) is an example of a signal (S1+N1) in a guard interval. Fig. 9(B) is an example of a signal (S2+N2) in a guard-equivalent interval. The noise in the guard interval signal (S1+N1) and the noise in the guard-equivalent interval signal (S2+N2) do not perfectly match.

[0064] Fig. 10(A) is an example of noise (N1) in the guard interval. Fig. 10(B) is an example of the first noise signal (N1-N2). As shown in Fig. 10(B), the first noise signal (N1-N2) has almost twice the number of pulse noise peaks as the noise (N1) in the guard interval. In other words, it can be seen that the power peaks of the pulse noise are shifted between the guard interval and the guard-equivalent interval.

[0065] Fig. 11(A) shows an example of the results of cross-correlation between the second noise signal over the entire symbol interval and the symbol interval performed by the cross-correlation unit 2252. In the data example of Fig. 11(A), the peak position of the cross-correlation is near the value 2 on the time axis. Fig. 11(B) shows the shifted and finally generated noise replica signal NR(t). In Fig. 11(B), zero data has been inserted up to the vicinity of the value 2 on the time axis, which corresponds to the peak position in Fig. 11(A).

[0066] 12 is a diagram illustrating a signal (ORG) before pulse noise removal and a signal (NC-OUT) after pulse noise removal, from which it can be seen that pulse noise is removed by the processing of this embodiment.

[0067] (Computer-readable recording medium) A program that causes a computer or other machine or device (hereinafter referred to as a computer, etc.) to realize any of the above functions can be recorded on a computer-readable recording medium. Then, by having the computer, etc. read and execute the program from this recording medium, the function can be provided.

[0068] Here, a computer-readable recording medium refers to a recording medium that stores information such as data and programs electrically, magnetically, optically, mechanically, or chemically and can be read by a computer. Examples of removable media include flexible disks, magneto-optical disks, CDs (Compact Discs), DVDs (Digital Versatile Discs), Blu-ray discs, and memory cards such as flash memory. Also, examples of recording media fixed to computers include hard disks and ROMs (Read Only Memory). Furthermore, SSDs (Solid State Drives) ) can be used as a recording medium that can be removed from a computer or the like, or as a recording medium that is fixed to a computer or the like. [Explanation of symbols]

[0069] 1 antenna 2 RF circuit 3 Baseband circuit 4 Amplifier 5 speakers 11 CPU 12 Main memory 13 External memory unit 14 Display section 15 Control section 16 Broadcast receiving unit 21 Amplification circuit 22 Noise removal circuit 23 Demodulation Circuit 221 Symbol Synchronization Unit 222 Guard section cutout 223 Guard equivalent section cut-out 224 Pulse noise detector 225 Noise Generation Unit 226, 2242 Adaptive filters

Claims

1. generating a first noise signal by calculating a difference between a guard interval added to the beginning of a data interval of the modulated signal and a guard-equivalent interval at the end of the data interval from which the guard interval is copied; processing the first noise signal with an adaptive filter to generate a second noise signal; a filter parameter of the adaptive filter is adjusted so as to minimize a difference between the signal in the guard interval or the signal in the guard-equivalent interval and the second noise signal; The second noise signal generated by the adjusted filter parameters is used as a noise replica signal to remove pulse noise included in the data section. Receiver.

2. 2. The receiver according to claim 1, wherein the second noise signal is repeatedly arranged to generate the noise replica signal having the entire length of the data section.

3. 3. The receiver according to claim 2, wherein the position of the noise replica signal on the time axis is shifted according to the peak position in the cross-correlation between the noise replica signal and the data section for the entire length of the data section, thereby aligning the relative positions of the data section and the noise replica signal.

4. 4. The receiver according to claim 3, wherein a partial interval on the time axis corresponding to the data interval in which the noise replica signal does not exist, which is generated by shifting the noise replica signal, is complemented with zero data.

5. 2. The receiver according to claim 1, wherein pulse noise is removed by using the noise replica signal generated by the signal in the guard interval in the first half of the data interval, and by using the noise replica signal generated by the signal in the guard-equivalent interval in the second half of the data interval.

6. A receiving system comprising a receiver and an output device, the receiver comprising: generating a first noise signal by calculating a difference between a guard interval added to the beginning of a data interval of the modulated signal and a guard-equivalent interval at the end of the data interval from which the guard interval is copied; processing the first noise signal with an adaptive filter to generate a second noise signal; a filter parameter of the adaptive filter is adjusted so as to minimize a difference between the signal in the guard interval or the signal in the guard-equivalent interval and the second noise signal; The second noise signal generated by the adjusted filter parameters is used as a noise replica signal to remove pulse noise included in the data section. Receiving system.

7. The receiver, generating a first noise signal by calculating a difference between a guard interval added to the beginning of a data interval of the modulated signal and a guard-equivalent interval at the end of the data interval from which the guard interval is copied; processing the first noise signal with an adaptive filter to generate a second noise signal; a filter parameter of the adaptive filter is adjusted so as to minimize a difference between the signal in the guard interval or the signal in the guard-equivalent interval and the second noise signal; The second noise signal generated by the adjusted filter parameters is used as a noise replica signal to remove pulse noise included in the data section. Receiving method.

8. To the receiver, generating a first noise signal by calculating a difference between a guard interval added to the beginning of a data interval of the modulated signal and a guard-equivalent interval at the end of the data interval from which the guard interval is copied; processing the first noise signal with an adaptive filter to generate a second noise signal; a filter parameter of the adaptive filter is adjusted so as to minimize a difference between the signal in the guard interval or the signal in the guard-equivalent interval and the second noise signal; a process for removing pulse noise included in the data section using the second noise signal generated by the adjusted filter parameters as a noise replica signal; program.

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