WO2007091562A1 - 復調装置、方法及びプログラム - Google Patents
復調装置、方法及びプログラム Download PDFInfo
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- WO2007091562A1 WO2007091562A1 PCT/JP2007/052033 JP2007052033W WO2007091562A1 WO 2007091562 A1 WO2007091562 A1 WO 2007091562A1 JP 2007052033 W JP2007052033 W JP 2007052033W WO 2007091562 A1 WO2007091562 A1 WO 2007091562A1
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- complex multiplication
- interference wave
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- 238000000034 method Methods 0.000 title claims description 44
- 230000003111 delayed effect Effects 0.000 claims abstract description 17
- 238000001514 detection method Methods 0.000 claims description 56
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 25
- 230000001934 delay Effects 0.000 claims description 6
- 238000012935 Averaging Methods 0.000 description 21
- 238000006243 chemical reaction Methods 0.000 description 21
- 230000005540 biological transmission Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 9
- 239000000284 extract Substances 0.000 description 3
- 230000002411 adverse Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
- H04N5/455—Demodulation-circuits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/015—High-definition television systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/22—Demodulator circuits; Receiver circuits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/38—Demodulator circuits; Receiver circuits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving encoded video stream packets from an IP network
- H04N21/4382—Demodulation or channel decoding, e.g. QPSK demodulation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/14—Picture signal circuitry for video frequency region
- H04N5/21—Circuitry for suppressing or minimising disturbance, e.g. moiré or halo
- H04N5/211—Ghost signal cancellation
Definitions
- the present invention relates to a demodulation apparatus and method for receiving a signal modulated according to Orthogonal Frequency Division Multiplexing (OFDM) system and demodulating the modulated signal, and more specifically, interference due to analog TV broadcast
- the present invention relates to a demodulation device and method for removing waves, and a program that causes a computer to execute this demodulation process.
- OFDM Orthogonal Frequency Division Multiplexing
- the interference wave When an interference wave is present in the received signal, the interference wave can be removed to improve the reception performance by operating a filter that cancels the interference wave. On the other hand, if the filter operates when there is no interference in the received signal, the reception performance will be adversely degraded. Therefore, in order to control the operation Z inactivity of the filter, accurately detecting whether or not an interference wave is included in the received signal is an important factor in determining the performance of the receiver.
- FIG. 1 is a diagram showing a transmitting device 100 and a receiving device 200.
- the transmitter 100 modulates and transmits a bit data string to be transmitted according to the OFDM method.
- the transmitting apparatus 100 includes a data generation unit 101, an IFFT processing unit 102, a parallel-serial conversion processing unit 103, an RF processing unit 104, and an antenna 105.
- the data generation unit 101 generates a bit data string to be transmitted.
- the IFFT processing unit 102 applies IFFT (Inverse Fast Fourier Transform) to the bit data string generated by the data generation unit 101.
- the parallel-serial conversion processing unit 103 converts the bit data sequence subjected to the IFFT processing by the IFFT processing unit 102 into a serial symbol data sequence in symbol units.
- the RF processing unit 104 converts the symbol data string converted by the parallel-serial conversion processing unit 103 into an OFDM signal multiplied by a carrier wave.
- the antenna 105 transmits the OFDM signal output from the RF processing unit 104 to the receiver 200 via the transmission path.
- the receiver 200 receives the OFDM signal transmitted by the transmitter 100, and demodulates the received signal according to the OFDM scheme.
- the receiving apparatus 200 includes an antenna 201, a frequency conversion unit 202, an interference wave removal filter 203, a serial-parallel conversion processing unit 204, an FFT processing unit 205, an error correction processing unit 206, and an interference wave detection unit 207. Equipped with
- the antenna 201 receives an OFDM signal from the transmission line.
- the frequency converter 202 converts the OFDM signal received by the antenna 201 into an IF signal of the intermediate frequency of the carrier wave.
- the interference wave removal filter 203 reduces frequency components including interference waves from the IF signal converted by the frequency conversion unit 202.
- the serial-to-parallel conversion processing unit 204 performs serial-to-parallel conversion processing on the symbol data string of the IF signal from which the interference component is removed by the interference wave removal filter 203 to convert it into a bit data string.
- the FFT processing unit 205 performs T FFT (Fast Fourier Transform processing) on the bit data string converted by the serial-to-parallel conversion processing unit 204.
- the error correction processing unit 206 performs predetermined error correction processing on the bit data string subjected to the FFT processing by the FFT processing unit 205.
- the interference wave detection unit 207 detects whether the interference wave component is included in the bit data string subjected to the FFT processing by the FFT processing unit 205 or not.
- an interference wave detection unit 207 that detects an interference wave is provided at the rear stage of the FFT processing unit 205 that performs FFT processing on the received signal, and the detection result by the interference wave detection unit 207 is In response, the operation of the interference wave removal filter 203 provided in the front stage of the FFT unit is turned on. Disclosure of the Invention Problem to be Solved by the Invention
- the interference wave included in the received signal is reliably detected in the front stage of the FFT processing unit, and the interference wave is removed in the front stage of the FFT processing unit.
- a demodulator receives a signal modulated by an orthogonal frequency division multiplexing (OFDM) scheme to solve the above-mentioned problem, and demodulates the modulated signal.
- Orthogonal demodulation means for orthogonally demodulating a modulated signal to generate a complex signal including real axis component and imaginary axis component, and complex conjugate signal for generating a complex conjugate signal of the complex signal generated by the orthogonal modulation means Generation means, delay means for delaying the complex conjugate signal generated by the complex conjugate signal generation means by an integral multiple of a predetermined period, complex signal generated by the orthogonal demodulation means, and delay means for the predetermined period
- Complex multiplication means for performing complex multiplication based on a complex conjugate signal delayed by an integer multiple, complex multiplication value obtained by complex multiplication by the above complex multiplication means and arbitrary threshold value and ratio
- it comprises determination means for determining whether or not the modulation signal includes an interference wave, and interference wave removal means for removing the interference wave from the modulation
- a signal modulated by orthogonal frequency division multiplexing is received, and the modulated signal is demodulated.
- Orthogonal demodulation of the modulation signal to generate a complex signal including real axis components and imaginary axis components, and complex complex signals of the complex signal generated by the orthogonal demodulation process.
- a conjugate signal generation step, a delay step of delaying the complex conjugate signal generated by the complex conjugate signal generation step by an integral multiple of a predetermined period, and a complex signal generated by the orthogonal demodulation step A complex multiplication step of performing complex multiplication based on a complex conjugate signal delayed by an integral multiple of a predetermined period of time by the delay step; and a complex multiplication value obtained by complex multiplication by the complex multiplication step with an arbitrary threshold value.
- the method includes a determination step of comparing and determining whether or not the modulation signal includes an interference wave, and an interference wave removal step of removing the interference wave from the modulation signal based on the determination result of the determination step.
- a program according to the present invention receives a signal modulated by orthogonal frequency division multiplexing (OFDM) method and performs demodulation processing for demodulating the modulated signal.
- the orthogonal demodulation process of orthogonally modulating the modulation signal to generate a complex signal including a real axis component and an imaginary axis component, and the complex signal generated by the orthogonal demodulation process.
- FIG. 1 is a block diagram showing a configuration of a conventional receiving apparatus.
- FIG. 2 is a diagram showing an OFDM signal, an OFDM symbol, an effective symbol, a guard interval, and an FFT window.
- FIG. 3 is a block diagram showing the configuration of a receiving apparatus according to the present invention.
- FIG. 4A is a diagram showing the scanning line direction on the screen of a National Television System Committee (NTSC) video signal (color burst signal), and FIG. 4B is a diagram showing an NTSC video signal (color burst signal). It is.
- FIG. 5 is a flowchart for explaining the demodulation processing steps in the receiving apparatus.
- FIG. 6 is a block diagram showing a first configuration example of an interference wave detection unit provided in the receiving apparatus according to the present invention.
- FIG. 7 is a flowchart for explaining a disturbance wave detection process step in the first configuration example.
- FIG. 8 is a block diagram showing a second configuration example of an interference wave detection unit provided in the receiving apparatus according to the present invention.
- FIG. 9 is a flowchart for explaining a disturbance wave detection process step in the second configuration example.
- the signal received by the digital television broadcast receiver is , May contain NTSC signals.
- the signal of the NTSC is detected and removed from the strength of the correlation at the front stage of the FFT (Fast Fourier Transform) arithmetic circuit.
- a receiving apparatus adopts ISDB-T (Integrated Services Digital Broadcast! Ng-Terrestrial) standard, and receives a signal modulated by orthogonal frequency division multiplexing (OFDM) system, Demodulates the modulated signal.
- OFDM orthogonal frequency division multiplexing
- a number of orthogonal subcarriers are provided in a transmission band, and the amplitude and phase of each subcarrier are corrupted by PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation).
- PSK Phase Shift Keying
- QAM Quadrature Amplitude Modulation
- the OFDM symbol to be processed at present is S (0), and the OFDM symbol S ( ⁇ 1) and the OFDM symbol S (one) before and after this OFDM symbol S (0) respectively. l).
- the OFDM symbol S (0) to explain the configuration of the OFDM symbol.
- This OFDM symbol S (0) is an effective symbol A (S (0)) which is a signal period in which IFFT (Inverse Fast Fourier Transform) calculation is performed at the time of transmission, and the second half of this effective symbol A (S (0))
- the part of the waveform of is composed of the guard interval GI (S (0)) copied as it is.
- This guard interval GI (S (0)) is provided in the front half of the OFDM symbol S (0), and for example, a time length of 1/4 or 1/8 of the effective symbol A (S (0)) It is supposed to be a signal of
- an FFT operation is performed by an FFT (Fast Fourier Transform) operation circuit to perform demodulation of the received OFDM signal.
- the OFDM receiver detects the boundary position of the OFDM symbol for the OFDM symbol composed of the effective symbol and the guard interval. And ⁇
- the FDM receiver defines an operation range (FFT window) of the same length as the effective symbol from the detected symbol boundary position, identifies the data of the portion defined by this FFT window from the OFDM symbol, and performs FFT Perform an operation.
- the receiver 1 includes, as shown in FIG. 3, an antenna 11, a frequency conversion circuit 12, a local oscillator 13, an A / D conversion circuit 14, a quadrature demodulation circuit 15, a carrier synchronization circuit 16, and a local oscillation.
- the oscillator 17, the interference cancellation filter 18, the interference detection unit 19, the FFT operation circuit 20, the equalization circuit 21, and the error correction circuit 22 are provided.
- the broadcast wave of the digital broadcast broadcasted from the broadcast station is the antenna 1 of the OFDM receiver 1 1 and supplied to the frequency conversion circuit 12 as an RF signal of the carrier frequency fc
- the RF signal received by the antenna 11 is the carrier signal of the carrier frequency fc + flF oscillated by the local oscillator 13 and the frequency conversion circuit
- the frequency is converted to an IF signal of an intermediate frequency fIF by being multiplied at 12 and supplied to the AZD conversion circuit 14.
- the IF signal is digitized by the AZD conversion circuit 14 and supplied to the quadrature demodulation circuit 15.
- the quadrature demodulation circuit 15 quadrature demodulates the digitized IF signal using the carrier signal of the intermediate frequency fIF oscillated by the local oscillator 17 controlled by the carrier synchronization circuit 16 and outputs a baseband OFDM signal.
- the baseband OFDM signal output from the orthogonal demodulation circuit 15 is a so-called time domain signal before the FFT operation is performed. From this, the baseband signal before the FFT operation is performed after quadrature demodulation is called an OF DM time domain signal.
- the OFDM time domain signal becomes a complex signal including an actual axis component (I channel signal) and an imaginary axis component (Q channel signal).
- the OFDM time domain signal output from the quadrature demodulation circuit 15 is supplied to a carrier synchronization circuit 16, an interference cancellation filter 18 and an interference detection unit 19.
- the interference cancellation filter 18 is a filter for removing the interference contained in the OFDM time domain signal supplied from the quadrature demodulation circuit 15.
- the interference wave detection unit 19 detects the interference wave contained in the OFDM time domain signal supplied from the orthogonal demodulation circuit 15 and controls the operation of the interference wave cancellation filter 18 according to the detection result.
- the FFT operation circuit 20 performs an FFT operation on the OFDM time domain signal in which the interference wave is canceled, and extracts and outputs data orthogonally modulated on each subcarrier.
- the signal output from the FFT operation circuit 20 is a so-called frequency domain signal after the FFT operation is performed. Due to this fact, the signal after the FFT operation is performed is called an OFDM frequency domain signal.
- the FFT operation circuit 20 extracts a signal of a range of effective symbol lengths (for example, 2048 samples) from one OFDM symbol, that is, extracts 2048 samples of OFDM extracted by excluding a range of guard interval from one OFDM symbol.
- a range of effective symbol lengths for example, 2048 samples
- For time domain signals Perform FFT operation.
- the operation start position is any position from the boundary of the OFDM symbol to the end position of the guard interval. This operation range is called an FFT window.
- Equalization circuit 21 corrects distortion generated in the transmission path with respect to the OFDM frequency domain signal supplied from FFT operation circuit 20, and outputs the corrected OFDM frequency domain signal to error correction circuit 22.
- the FFT operation circuit 20 performs distortion correction on the amplitude and phase of the OFDM frequency domain signal based on a pilot signal previously included in the OFDM frequency domain signal.
- the error correction circuit 22 performs dinning processing on the OFDM frequency domain signal whose distortion has been corrected by the equalization circuit 8. Furthermore, the error correction circuit 22 performs Viterbi decoding processing, Reed-Solomon decoding processing, and the like on the signal after dinning processing, and demodulates the OFDM frequency domain signal into information data.
- the OFDM frequency domain signal output from the FFT operation circuit 20 is, like the OFDM time domain signal, a complex signal including the real axis component (I channel signal) and the imaginary axis component (Q channel signal). It has become.
- This complex signal is, for example, a signal that has been quadrature amplitude modulated by the 16 QAM method or the 64Q AM method.
- the interference cancellation filter 18 and the interference detection unit 19 will be described in detail.
- the desired signal is an OFDM time domain signal and the interference wave is an analog television signal (NTSC video signal).
- An NTSC video signal is a signal in which a picture to be transmitted is divided into points called picture elements, and those picture elements are sequentially called out on the scanning line from the upper left to the lower right of the screen (FIG. 4A). Also, the NTSC video signal is divided into a luminance signal and a color signal, and signals to which various synchronization signals indicating the position of each picture element are added are subjected to residual wave band (VSB, vestigial side band) modulation and transmitted. It is.
- FIG. 4B is a diagram showing the time waveform of the NTSC video signal (base band signal) after the horizontal synchronization signal HS is added. The signal waveform of the color burst signal is also shown in FIG. 4 (b).
- the baseband signal is 63 ⁇ 556 ⁇ sec (hereinafter, this period is 1H (horizontal Synchronization period). )
- Each line has a repeating pattern of one line.
- synchronization signal sections inserted in each line are called horizontal blanking sections, and the synchronization signals of the color subcarrier in the latter half of them are called color burst signals A and B.
- the color burst signals A and B become reference signals of the color signal.
- the frequency of this reference signal is 3.58 MHz, and in NTSC, it is set to 445/2 times the horizontal synchronization frequency. Therefore, the color signal is a signal in which the phase is inverted every line (see A and B in FIG. 4B).
- the NTSC video signal is included in the signal modulated by the OFDM method. Therefore, the interference cancellation filter 18 and the interference detection unit 19 of the receiver 1 detect the NTSC video signal included in the OFDM time domain signal as an interference using the periodicity of the NTSC signal. And remove.
- the interference wave detection unit 19 is specifically configured by an autocorrelator having a delay of a periodic interval.
- demodulation processing is realized by operating the above-described respective processing units according to the flowchart shown in FIG.
- step S 11 the antenna 11 receives a broadcast wave of digital broadcasting, and outputs an RF signal of the carrier frequency fc to the frequency conversion circuit 12 from the received digital broadcast wave.
- step S12 the frequency conversion circuit 12 converts the RF signal of the carrier frequency fc supplied from the antenna 11 into an IF signal of the intermediate frequency fIF, and supplies the IF signal to the A / D conversion circuit 14.
- step S 13 the AZD conversion circuit 14 digitizes the IF signal of the intermediate frequency fIF supplied from the frequency conversion circuit 12 and supplies it to the quadrature demodulation circuit 15.
- step S14 the orthogonal demodulation circuit 15 orthogonally demodulates the IF signal supplied from the AZD conversion circuit 14, and supplies the baseband OFDM time domain signal to the interference cancellation filter 18 and the interference detection unit 19, respectively.
- step S15 the interference wave detection unit 19 performs interference wave detection processing to determine whether the broadcast wave contains an interference wave. In the demodulation processing step, this judgment processing If the broadcast wave includes an interference wave, the process proceeds to step S16. If the broadcast wave does not include an interference wave, the process proceeds to step S17. The specific determination process will be described later.
- step S16 the interference cancellation filter 18 removes interference that is included in the OFDM time domain signal supplied from the orthogonal demodulation circuit 15, and supplies this signal to the FFT calculation circuit 20. When it is determined in step S15 that the interference wave is not included in the broadcast wave, the interference wave cancellation filter 18 supplies the OF DM time domain signal to the FFT operation circuit 20 without filtering.
- step S17 the FFT operation circuit 20 converts the OFDM time domain signal supplied from the interference cancellation filter 18 into an OFDM frequency domain signal, and supplies this signal to the equalization circuit 21.
- step S18 the equalization circuit 21 performs distortion correction on the OFDM frequency domain signal supplied from the FFT operation circuit 20 and supplies the corrected signal to the error correction circuit 22.
- step S19 the error correction circuit 22 performs dinning-leave processing, Viterbi decoding processing, Reed-Solomon decoding processing, etc. on the OFD M frequency domain signal distortion-corrected by the equalization circuit 8 to obtain an OFDM frequency domain signal. Demodulates to information data such as image data and audio data.
- the receiving device 1 is not limited to the case where each processing unit is configured by hardware, and may be configured to cause a computer to execute a program based on the above-described processing steps.
- the interference wave detection unit 19 includes a complex conjugate signal generation unit 31, a delay unit 32, a complex multiplication unit 33, and a determination unit 34.
- the complex conjugate signal generation unit 31 receives the OFDM time supplied from the orthogonal demodulation circuit 15.
- the delay unit 32 that generates a complex conjugate signal of the domain signal (a complex signal including an I channel signal and a Q channel signal) is supplied from the complex conjugate signal generation unit 31 to calculate autocorrelation. Processing to delay the complex conjugate signal by an integral multiple of 1H or an integral multiple of 2H.
- the complex multiplication unit 33 performs complex multiplication based on the complex signal generated by the orthogonal demodulation circuit 15 and the complex conjugate signal delayed by an integral multiple of a predetermined period by the delay unit 32.
- the determination unit 34 compares the complex multiplication value obtained by the complex multiplication by the complex multiplication unit 33 with an arbitrary threshold to determine whether or not the modulation signal includes an interference wave.
- the delay amount by the delay unit 32 is preferably an integral multiple of 1H or an integral multiple of 2H.
- the delay unit 32 detects a color signal component included in an OFDM time domain signal, it is necessary to make the delay amount an integral multiple of 2H. This is because the color burst signal power included in the color signal is inverted every 1H. That is, if the delay amount is an integral multiple of 1H, the correlation becomes low due to the color burst signal in the operation performed by the complex multiplication unit 33 in the subsequent stage. Due to such a cause, the interference wave detection unit 19 can not accurately detect the NTSC video signal unless the delay amount is set to an integral multiple of 2H.
- the image transmitted from the transmitting side is generally Since the color bar screen is an image with changes such as a movie, etc., there is only a limited amount of correlation that can always be taken at an integer multiple of 1H. However, even in the case of a normal image, it is considered that a large change in the picture is unlikely to be caused by a few lines apart, and it is considered that a sufficiently large correlation can be obtained within a relatively small delay range.
- the determination unit 34 includes an average calculation unit 41, a calculation unit 42, and a comparison determination unit 43.
- the averaging unit 41 performs averaging of a plurality of complex multiplication values obtained by the complex multiplication by the complex multiplication unit 33.
- the calculating unit 42 calculates the amplitude or power of the complex multiplication value averaged by the averaging unit 41.
- the comparison / determination unit 43 compares the amplitude or power of the complex multiplication value calculated by the calculation unit 42 with an arbitrary threshold value, and determines whether the OFDM time domain signal includes an NTSC video signal as follows. To judge.
- the comparison and determination unit 43 determines the amplitude of the complex multiplication value calculated by the calculation unit 42 or When the power exceeds an arbitrary first threshold TH1, it is determined that the OFDM time domain signal includes an interference wave (NTSC video signal). In addition, when the amplitude or power of the complex multiplication value calculated by the calculation unit 42 falls below an arbitrary second threshold TH2, the comparison and determination unit 43 generates an interference wave (NTSC video signal) in the OFDM time domain signal. Is not included.
- the first threshold TH1 is a value larger than the second threshold TH2.
- the first threshold value TH1 and the second threshold value Th2 are arbitrarily set by the user interface provided in the receiving device 1. These threshold values are not limited to the case where they are set by the user. For example, they may be recorded in advance in a register provided in the receiving device 1 and read out from this register to the comparison / determination unit 43.
- the comparison / determination unit 43 determines that the OFDM time domain signal contains an NTSC signal, it turns on the operation of the interference cancellation filter 18, and the OFDM time domain signal contains an NTSC signal. If it is determined that there is not, the operation of the disturbance wave cancellation filter 18 is turned off. The correlation is high when the NTSC video signal is included in the OFDM time domain signal. On the other hand, the OFDM time domain signal includes the NT SC video signal, and the correlation is low.
- the interference wave detection unit 19 detects interference waves by operating each processing unit constituting the interference wave detection unit 19 described above according to the flowchart shown in FIG. Note that this processing step corresponds to step S15 in the processing steps of the receiving device 1 described above. That is, as a premise, the processing steps described below are started on the basis of the processing end time of step S14 described above.
- step S 21 the complex conjugate signal generation unit 31 generates a signal of a component to be a complex conjugate with respect to the OFDM time domain signal supplied from the orthogonal demodulation circuit 15, and transmits the complex conjugate signal to the delay unit 32. Supply.
- step S22 the delay unit 32 delays the complex conjugate signal supplied from the complex conjugate signal generation unit 31 by an integral multiple of 1H or an integral multiple of 2H. Then, the delay unit 32 supplies the delayed complex conjugate signal to the complex multiplication unit 33.
- step S23 the complex multiplication unit 33 delays the delay unit 32 by an integral multiple of a predetermined period. Complex multiplication is performed on the basis of the complex signal thus obtained and the complex signal directly supplied from the quadrature demodulation circuit 15. Then, the complex multiplication unit 33 supplies the complex multiplication value obtained by the complex multiplication to the averaging unit 41.
- step S24 the averaging unit 41 performs averaging of a plurality of complex multiplication values obtained by the complex multiplication by the complex multiplication unit 33.
- the averaging unit 41 supplies the averaged complex multiplication value to the calculating unit 42.
- step S 25 the calculation unit 42 calculates the amplitude or power of the averaged complex multiplication value supplied from the average calculation unit 41. Then, the calculation unit 42 supplies the calculated amplitude or power to the comparison and determination unit 43.
- step S26 the comparison / determination unit 43 determines whether the amplitude or power calculated by the calculation unit 42 exceeds the first threshold TH1. If the comparison / determination unit 43 determines that the first threshold TH1 is exceeded, the process proceeds to step S16, and if it is determined that the first threshold TH1 is not exceeded, the process proceeds to step S27.
- step S27 the comparison / determination unit 43 determines whether the amplitude or power calculated by the calculation unit 42 is below the second threshold TH2. If the comparison / determination unit 43 determines that the second threshold TH2 is exceeded, the process proceeds to step S17. If the comparison determination unit 43 determines that the second threshold TH2 is not exceeded, the process proceeds to step S16.
- step S16 and step S17 and subsequent steps are the same as described above, and the description thereof will be omitted.
- the interference wave detection unit 19 is not limited to the case where each processing unit is configured by hardware, and the computer is made to execute a program based on the above-described processing steps. Also good.
- the interference wave detection unit 19 calculates autocorrelation of the OFDM time domain signal by an integral multiple of 1H or an integral multiple of 2H, and the presence or absence of the correlation determines that the NTSC video signal is included in the OFDM time domain signal. Since it is possible to adaptively switch the operation of the disturbance cancellation filter 18 according to the detection, it is possible to accurately detect smaller disturbances without causing the transmission path condition. It is possible to maintain the performance of the receiver 1 at a constant level.
- the disturbance wave detection unit 19 uses the noise component (hereinafter referred to as a background component) uniformly contained in the transmission path to detect the disturbance wave detection accuracy. It will improve.
- a background component the noise component
- the interference wave detection unit 19 includes a complex conjugate signal generation unit 51, a delay unit 52, a complex multiplication group 53, a background component detection unit 54, and a determination unit 55.
- the complex conjugate signal generation unit 51 generates a complex conjugate signal of the OFDM time domain signal (a complex signal including an I channel signal and a Q channel signal) supplied from the orthogonal demodulation circuit 15.
- the delay unit 52 performs autocorrelation. In order to calculate, the complex conjugate signal supplied from the complex conjugate signal generation unit 51 is delayed by an integral multiple of 1H or an integral multiple of 2H. Parallel to this processing, the delay unit 52 also performs processing to delay the complex conjugate signal supplied from the complex conjugate signal generation unit 51 by an arbitrary multiple other than an integer multiple.
- the complex multiplication group 53 performs complex multiplication based on the complex signal generated by the orthogonal demodulation circuit 15 and the complex conjugate signal D1 delayed by an integer multiple of 1H or an integer multiple of 2H by the delay unit 52.
- the ground component detection unit 54 performs complex multiplication based on the complex conjugate signal D2 delayed by an arbitrary multiple other than an integer multiple by the delay unit 52 and the complex signal generated by the orthogonal demodulation circuit 15, The ground component is detected.
- the determination unit 55 subtracts the background component detected by the background component detection unit 54 from the complex multiplication value obtained by the complex multiplication by the complex multiplication group 53, and sets the complex multiplication value after subtraction to an arbitrary threshold value. Compare with to determine whether the modulation signal contains an interference wave.
- the above-described background component detection unit 54 includes a complex multiplication unit 61, an average calculation unit 62, and a calculation unit 63.
- the complex multiplication unit 61 performs complex multiplication based on the complex conjugate signal D 2 delayed by an arbitrary multiple other than an integer multiple by the delay unit 52 and the complex signal generated by the orthogonal demodulation circuit 15.
- the averaging unit 62 performs averaging of a plurality of complex multiplication values obtained by the complex multiplication by the complex multiplication unit 61.
- the calculating unit 63 calculates the amplitude or the power of the complex multiplication value averaged by the averaging unit 62.
- the output of the calculation unit 63 is a backland component.
- the determination unit 55 includes an average calculation group 71, a calculation group 72, an calculation group 73, and a comparison determination unit 74.
- the averaging operation group 71 performs averaging of a plurality of complex multiplication values obtained by the complex multiplication by the complex multiplication group 53, respectively.
- the calculation group 72 calculates the amplitude or power of the complex multiplication value averaged by the averaging group 71, respectively.
- the calculation group 73 removes the background component supplied from the calculation unit 63 of the nock ground component detection unit 54 from the respective outputs of the calculation group 72.
- the comparison / determination unit 74 refers to an arbitrary threshold based on the result calculated by the calculation group 73, and determines whether or not the OFDM time domain signal includes an NTSC video signal.
- the interference wave detection unit 19 detects interference waves by operating the respective processing units constituting the interference wave detection unit 19 described above according to the flowchart shown in FIG. This processing step corresponds to step S15 among the processing steps of the receiving apparatus 1 described above. Therefore, as a premise, the processing steps described below are started on the basis of the processing end time of step S14 described above.
- step S31 the complex conjugate signal generation unit 51 generates a complex conjugate signal of the OFDM time domain signal supplied from the orthogonal demodulation circuit 15. Then, the complex conjugate signal generation unit 51 supplies the generated complex conjugate signal to the delay unit 52.
- the interference wave detection unit 19 After completion of step S31, the interference wave detection unit 19 performs two processes of the interference wave component detection process of the following steps S32 to S35 and the background component detection process of the steps S36 to S39 in parallel. First, the interference wave component detection step will be described.
- step S32 the delay unit 52 performs processing to delay the complex conjugate signal supplied from the complex signal generator 51 by an integer multiple of 1 H and an integer multiple of 2 H in order to calculate the correlation of interference components. . Then, the delay unit 52 is configured to delay the complex delayed at a plurality of different intervals. The conjugate signal is supplied to each complex multiplier constituting the complex multiplication group 53.
- each complex multiplier configuring the complex multiplier group 53 performs complex multiplication based on the complex conjugate signal supplied from the delay unit 52 and the complex signal directly supplied from the orthogonal demodulation circuit 15. Then, each complex multiplication unit constituting the complex multiplication group 53 supplies the average operation unit constituting the average operation group 71, respectively.
- each averaging operation unit constituting the averaging operation group 71 performs averaging of a plurality of complex multiplication values obtained by each complex multiplication unit constituting the complex multiplication group 53. Then, each averaging operation unit constituting the averaging operation group 71 supplies the averaged complex multiplication value as an interference wave component to each operation unit constituting the operation group 73.
- step S40 the background component detection step will be described.
- step S36 the delay unit 52 delays the complex conjugate signal supplied from the complex conjugate signal generation unit 51 by an arbitrary multiple other than an integer multiple. Then, the delay unit 52 supplies the complex multiplication unit 61 with a complex conjugate signal delayed by any multiple other than an integer multiple.
- step S 37 the complex multiplication unit 61 performs complex multiplication based on the delayed complex conjugate signal supplied from the delay unit 52 and the complex signal directly supplied from the orthogonal demodulation circuit 15. Then, the complex multiplication unit 61 supplies the complex multiplication value obtained by the complex multiplication to the averaging unit 62.
- step S 38 the averaging unit 62 averages the complex multiplication values supplied from the complex multiplication unit 61. Then, the average calculation unit 62 supplies the average value of the complex multiplication values to the calculation unit 63.
- step S39 the calculating unit 63 calculates the amplitude or power of the complex multiplication value from the average value of the complex multiplication values supplied from the averaging unit 62. Then, the calculation unit 63 supplies the calculated amplitude or power as a background component to each calculation unit constituting the calculation group 73.
- each operation unit constituting the operation group 73 calculates the difference between the interference wave component supplied from each calculation unit constituting the calculation group 72 and the background component supplied from the calculation unit 63. Then, each operation unit configuring operation group 73 compares and determines the operation results. Supply to section 74.
- step S41 the comparison / determination unit 74 determines whether the amplitude or the power of the calculation result supplied from each calculation unit constituting the calculation group 73 exceeds the first threshold TH1. If the comparison / determination unit 74 determines that the first threshold TH1 is exceeded, the process proceeds to step S16, and if it is determined that the first threshold TH1 is not exceeded, the process proceeds to step.
- step S42 the comparison / determination unit 74 determines whether the amplitude or the power of the calculation result supplied from each calculation unit constituting the calculation group 73 falls below the second threshold TH2. Then, the comparison / determination unit 74 proceeds to step S17 when determining that it is below the second threshold TH2, and proceeds to step S16 when it is determined that it is not below the second threshold TH2.
- the description of the process of step S16 and step S17 is omitted.
- the disturbance wave detection unit 19 is not limited to the case where each processing unit is configured by hardware, and may adopt a configuration that causes a computer to execute a program based on the above-described processing.
- the interference wave detection unit 19 obtains autocorrelations for a plurality of delays, and detects the presence or absence of the NTSC video signal comprehensively. Specifically, as shown in FIG. 8, the disturbance wave detection unit 19 calculates autocorrelation of integer multiples of 1H and autocorrelation of other multiples, and averages the autocorrelation output of integer multiples of 1H. The detection of an NTSC video signal is performed using a value obtained by dividing the amplitude (or power) by an autocorrelation output average amplitude other than an integer multiple of 1H. Therefore, the interference wave detection unit 19 can cancel the background component of the self-correlation output due to interference waves other than the NTSC video signal, and reduce the false detection probability. As a result, it is possible to detect an NTSC video signal with higher accuracy than the configuration of the first embodiment described above.
- the interference wave detection unit 19 finds the autocorrelation of a plurality of delays for the OFDM time domain signal, and the NTSC video signal is included in the OFDM time domain signal depending on the presence or absence of the overall correlation. Since it is possible to detect the presence of interference and adaptively switch the operation of the interference cancel filter 18 according to the detection, it is possible to detect a smaller interference with high accuracy regardless of the state of the transmission path. It is possible to maintain the performance of the receiver 1 itself at a fixed level. Furthermore, the present invention is not limited to the above-described embodiment described with reference to the drawings, and various changes, substitutions or equivalents may be made without departing from the scope of the appended claims and the subject matter thereof. Of course it can be done.
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Abstract
Description
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Priority Applications (5)
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JP2007557848A JP4911038B2 (ja) | 2006-02-06 | 2007-02-06 | 復調装置、方法及びプログラム |
US11/908,874 US7889802B2 (en) | 2006-02-06 | 2007-02-06 | Demodulating device, method and program |
EP07713862A EP1983673B1 (en) | 2006-02-06 | 2007-02-06 | Demodulating device, method and program |
ES07713862T ES2399308T3 (es) | 2006-02-06 | 2007-02-06 | Dispositivo, método y programa de desmodulación |
KR1020077022678A KR101310496B1 (ko) | 2006-02-06 | 2007-02-06 | 복조 장치, 방법 및 프로그램이 기록된 기록매체 |
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JP2006-028699 | 2006-02-06 | ||
JP2006028699 | 2006-02-06 |
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PCT/JP2007/052033 WO2007091562A1 (ja) | 2006-02-06 | 2007-02-06 | 復調装置、方法及びプログラム |
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US (1) | US7889802B2 (ja) |
EP (1) | EP1983673B1 (ja) |
JP (1) | JP4911038B2 (ja) |
KR (1) | KR101310496B1 (ja) |
CN (1) | CN101310466A (ja) |
ES (1) | ES2399308T3 (ja) |
WO (1) | WO2007091562A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101132386A (zh) * | 2007-09-24 | 2008-02-27 | 杭州国芯科技有限公司 | 正交频分复用信号抑制干扰的方法 |
EP2288061A1 (en) * | 2008-07-25 | 2011-02-23 | Nippon Telegraph And Telephone Corporation | Reception device and reception method |
WO2011083773A1 (ja) * | 2010-01-07 | 2011-07-14 | パナソニック株式会社 | マルチキャリア変調信号受信装置及び集積回路 |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT1398155B1 (it) * | 2009-06-30 | 2013-02-14 | St Microelectronics Srl | Dispositivo elettronico per ricevere un segnale a radio-frequenza |
US9083444B2 (en) | 2013-03-12 | 2015-07-14 | Digi International Inc. | Chirp spread spectrum system and method |
US9438283B2 (en) * | 2014-05-23 | 2016-09-06 | Intel Corporation | Baseband time domain cancellation of data bus interference |
EP3942877A4 (en) * | 2019-03-18 | 2022-03-23 | ZTE Corporation | SYSTEMS AND METHODS FOR CONJUGATE DATA MODULATION |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11252040A (ja) * | 1998-03-04 | 1999-09-17 | Toshiba Corp | Ofdm受信装置 |
JP2000341243A (ja) * | 1999-03-25 | 2000-12-08 | Toshiba Corp | Ofdm伝送信号中継装置及び受信装置 |
JP2004247945A (ja) * | 2003-02-13 | 2004-09-02 | Toshiba Corp | Ofdm受信装置、半導体集積回路及びofdm受信方法 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2743967B1 (fr) * | 1996-01-18 | 1998-03-27 | France Telecom | Procede et dispositif de synchronisation temporelle d'un recepteur d'un signal multiporteuse |
JP2907804B1 (ja) * | 1998-01-30 | 1999-06-21 | 株式会社次世代デジタルテレビジョン放送システム研究所 | Ofdm受信装置 |
DE69906927T2 (de) * | 1999-03-25 | 2003-12-24 | Toshiba Kawasaki Kk | Zwischenverstärker eines OFDM-Übertragungssignals und Empfänger |
EP1039713B1 (en) * | 1999-03-26 | 2006-05-31 | Nec Corporation | Reduction of delay in multicarrier receivers |
US7324437B1 (en) * | 1999-11-27 | 2008-01-29 | Deutsche Telekom Ag | Method for co-channel interference cancellation in a multicarrier communication system |
JP4640754B2 (ja) * | 2001-09-28 | 2011-03-02 | 富士通株式会社 | Ofdm受信方法及びofdm受信装置 |
KR100510551B1 (ko) * | 2003-10-10 | 2005-08-26 | 삼성전자주식회사 | Ofdm 신호 심볼의 공통 위상 에러(cpe)를 제거하는ofdm 디모듈레이터 및 그 cpe 제거 방법 |
KR100587310B1 (ko) * | 2004-08-18 | 2006-06-08 | 엘지전자 주식회사 | 주파수 동기 장치 및 이를 적용한 dvb-h 수신 시스템 |
-
2007
- 2007-02-06 JP JP2007557848A patent/JP4911038B2/ja not_active Expired - Fee Related
- 2007-02-06 EP EP07713862A patent/EP1983673B1/en not_active Expired - Fee Related
- 2007-02-06 ES ES07713862T patent/ES2399308T3/es active Active
- 2007-02-06 US US11/908,874 patent/US7889802B2/en not_active Expired - Fee Related
- 2007-02-06 KR KR1020077022678A patent/KR101310496B1/ko not_active IP Right Cessation
- 2007-02-06 CN CNA2007800001534A patent/CN101310466A/zh active Pending
- 2007-02-06 WO PCT/JP2007/052033 patent/WO2007091562A1/ja active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11252040A (ja) * | 1998-03-04 | 1999-09-17 | Toshiba Corp | Ofdm受信装置 |
JP2000341243A (ja) * | 1999-03-25 | 2000-12-08 | Toshiba Corp | Ofdm伝送信号中継装置及び受信装置 |
JP2004247945A (ja) * | 2003-02-13 | 2004-09-02 | Toshiba Corp | Ofdm受信装置、半導体集積回路及びofdm受信方法 |
Non-Patent Citations (1)
Title |
---|
See also references of EP1983673A4 * |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101132386A (zh) * | 2007-09-24 | 2008-02-27 | 杭州国芯科技有限公司 | 正交频分复用信号抑制干扰的方法 |
CN101132386B (zh) * | 2007-09-24 | 2013-01-30 | 杭州国芯科技股份有限公司 | 正交频分复用信号抑制干扰的方法 |
EP2288061A1 (en) * | 2008-07-25 | 2011-02-23 | Nippon Telegraph And Telephone Corporation | Reception device and reception method |
CN102100023A (zh) * | 2008-07-25 | 2011-06-15 | 日本电信电话株式会社 | 接收装置及接收方法 |
EP2288061A4 (en) * | 2008-07-25 | 2011-11-16 | Nippon Telegraph & Telephone | RECEIVER AND RECEIVER METHOD |
US8594255B2 (en) | 2008-07-25 | 2013-11-26 | Nippon Telegraph And Telephone Corporation | Reception device and reception method |
WO2011083773A1 (ja) * | 2010-01-07 | 2011-07-14 | パナソニック株式会社 | マルチキャリア変調信号受信装置及び集積回路 |
Also Published As
Publication number | Publication date |
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US7889802B2 (en) | 2011-02-15 |
KR20080096355A (ko) | 2008-10-30 |
JP4911038B2 (ja) | 2012-04-04 |
CN101310466A (zh) | 2008-11-19 |
JPWO2007091562A1 (ja) | 2009-07-02 |
EP1983673A4 (en) | 2011-07-06 |
EP1983673A1 (en) | 2008-10-22 |
US20080192844A1 (en) | 2008-08-14 |
KR101310496B1 (ko) | 2013-09-24 |
EP1983673B1 (en) | 2012-09-05 |
ES2399308T3 (es) | 2013-03-27 |
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