WO2006106788A1 - 軽減装置および方法、ならびに受信装置 - Google Patents
軽減装置および方法、ならびに受信装置 Download PDFInfo
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- WO2006106788A1 WO2006106788A1 PCT/JP2006/306586 JP2006306586W WO2006106788A1 WO 2006106788 A1 WO2006106788 A1 WO 2006106788A1 JP 2006306586 W JP2006306586 W JP 2006306586W WO 2006106788 A1 WO2006106788 A1 WO 2006106788A1
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- overmodulation
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- 238000000034 method Methods 0.000 title claims abstract description 27
- 230000003044 adaptive effect Effects 0.000 claims abstract description 49
- 230000005684 electric field Effects 0.000 claims description 133
- 238000001514 detection method Methods 0.000 claims description 49
- 230000000116 mitigating effect Effects 0.000 claims description 27
- 238000004364 calculation method Methods 0.000 claims description 25
- 230000000694 effects Effects 0.000 claims description 25
- 230000008859 change Effects 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 10
- 230000009467 reduction Effects 0.000 abstract description 38
- 230000006866 deterioration Effects 0.000 abstract description 6
- 230000008569 process Effects 0.000 abstract description 4
- 230000007547 defect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 18
- 101150024356 ADF2 gene Proteins 0.000 description 14
- 238000007796 conventional method Methods 0.000 description 13
- 230000006870 function Effects 0.000 description 11
- 238000012545 processing Methods 0.000 description 11
- 238000012937 correction Methods 0.000 description 3
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- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
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- 101100228149 Drosophila melanogaster Trl gene Proteins 0.000 description 1
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- 230000002159 abnormal effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
- H04B1/1081—Reduction of multipath noise
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/1646—Circuits adapted for the reception of stereophonic signals
- H04B1/1661—Reduction of noise by manipulation of the baseband composite stereophonic signal or the decoded left and right channels
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0602—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using antenna switching
Definitions
- the present invention receives a radio wave modulated and transmitted by a modulation method with a constant amplitude.
- the present invention relates to a reduction device and method for reducing multipath noise received during propagation, and a reception device.
- the multipath noise reduction device 1 includes an adaptive filter (hereinafter referred to as “ADF”) 2.
- the receiving device 3 including the ADF 2 as the multipath noise reducing device 1 is modulated by a frequency modulation (FM) or phase modulation (PM) method, and is originally used for receiving radio waves having a constant amplitude.
- FM frequency modulation
- PM phase modulation
- Frequency- or phase-modulated radio waves are normally received with a constant amplitude, but if they are received in a separate state due to reflections, the amplitude changes due to the influence of multipath.
- the received signal is converted into an analog signal from a digital signal by an analog Z-digital converter (hereinafter abbreviated as “AD converter”) 4, and multipath noise is obtained by digital signal processing in ADF2.
- AD converter analog Z-digital converter
- the received signal with multipath noise reduced by ADF2 is detected by detector 5 and the modulated signal is demodulated.
- the frequency-modulated radio wave is, for example, an FM broadcast radio wave that is transmitted in the very high frequency (VHF) frequency band.
- the radio wave is received by the antenna 6 and a radio frequency (RF) signal corresponding to the electric field strength is output.
- the high-frequency signal is processed in the analog signal state by the analog reception processing unit 7 having an RF unit for high-frequency amplification and the like and an Ml X unit for frequency conversion.
- an intermediate frequency (IF) of about 10.7 MHz Output as a signal.
- the IF signal is converted to a digital signal by AD conversion 4 and given to ADF2.
- ADF2 includes variable filter section 8, coefficient memory 9, filter coefficient calculation means 10, and Includes rope calculation means 11.
- the amplitude variation of the IF signal converted into the digital signal is detected by the envelope calculating means 11, and the filter coefficient is calculated by the filter coefficient calculating means 10 so that the amplitude fluctuation is corrected.
- the variable filter unit 8 uses the filter coefficient stored in the coefficient memory 9 to remove the multipath effect on the IF signal.
- Figure 20 shows the configuration for arithmetic processing that removes multipath distortion caused by multipath effects from FM signals in ADF2.
- the digitalized IF signal X (n) input to ADF2 is cos (2 ⁇ fc / fs) signal and I signal decomposition means, where sampling frequency is fs and IF signal carrier frequency is fc.
- I signal xi (n) generated by multiplying by Q
- Q signal xq (n) generated by multiplying the signal of sin (2 ⁇ fc / fs) by the Q signal decomposing means 13.
- the I signal xi (n) and the Q signal xq (n) are input to the variable filter unit 8, the coefficient memory 9, and the filter coefficient update unit as the filter coefficient calculation means 10.
- Filter coefficients a (n) and b (n) are output from the filter coefficient update unit to the variable filter unit 8.
- the variable filter unit 8 outputs the result of the arithmetic processing by multiplying the input I and Q signals xi (n) and xq (n) by the coefficients a (n) and b ( ⁇ ), respectively, as output yi (n ), yq (n).
- the outputs yi (n) and yq (n) are respectively input to the FM detector 5, the filter coefficient update unit, and the envelope error calculation unit that is the envelope calculation unit 11.
- the envelope error calculation unit calculates the error e (n) and supplies it to the filter coefficient update unit.
- ADF2 as shown in Fig. 20 uses the property that the envelope signal of the FM-modulated received signal, which should be essentially constant, fluctuates due to multipath distortion, and adapts the process so that the envelope becomes constant. Perform and remove distortion automatically.
- the output signals yi (n) and yq (n) of the variable filter unit 8 are calculated and output by the following equations (1) and (2). Where N is the number of filter taps and N ⁇ k ⁇ N.
- y i (n) ⁇ (a k (n) x i (n-k-N)-b k (n) x q (n— k_N))
- y q (n) ⁇ (a k (n) x q (n k— N)-b k (n) x i (n-k-N))
- filter characteristics that can remove multipath distortion can be obtained by updating the filter coefficients a (n) and b (n) as needed.
- the filter coefficient update unit updates the coefficients a (n) and b (n) according to the following equations (3) and (4).
- ak (n + l) ak (n) — e (n) (xi (n— k N) yi (n)
- bk (n + l) bk (n) / z e (n) (xi (n—k—N) yq (n)
- Equations (3) and (4) ⁇ is called Step Size and is a constant that determines the degree of convergence of adaptive processing.
- e (n) is an error calculated by the envelope error calculation unit, and corresponds to the amplitude variation. ADF2 operates to minimize this envelope error, resulting in a constant IF signal envelope.
- the envelope error calculation unit calculates the envelope error e (n) by the following equation (5).
- Such an adaptive filter operation is called an LMS algorithm.
- FIG. 21 shows the relationship between the envelope error e (n) used in Equation (5) and the envelope signal env.
- the envelope env fluctuates around the envelope reference value A.
- the filter coefficient of ADF2 is controlled to eliminate FM signal force multipath noise, it works in the direction of automatically removing linear distortion other than multipath distortion, such as that generated in an intermediate frequency amplifier.
- ADF2 works to cause side effects.
- a side effect is that the ADF2 operates outside of a multipath situation, resulting in an impact or change in the original signal, resulting in distorted or uncomfortable sound.
- ADF2 detects the amplitude variation and performs an operation to correct the amplitude variation.
- distortion occurs in the sound obtained by detection.
- the overmodulation state is considered to occur due to the following two causes.
- the bandwidth of the receiver is controlled so as to remove the interference by the interference countermeasure function of the receiver under the radio wave conditions other than the desired received signal. In addition, even when the amount of frequency deviation is not overmodulation, it will be larger than the bandwidth.
- the amplitude of the received wave fluctuates due to white noise.
- ADF2 Sound is distorted by detecting and operating the amplitude fluctuation.
- the diversity reception method is generally effective.
- the antenna switching method is executed at the time of diversity reception, the amplitude fluctuation of the received signal will occur with the switching, causing side effects such as voice distortion.
- amplitude fluctuations occur due to antenna switching.
- An object of the present invention is to provide a reduction device and method capable of comfortably receiving a radio wave signal, and a reception device that can compensate for technical and performance disadvantages of a conventional method in reducing multipath noise by an adaptive filter. Is to provide.
- the present invention includes an adaptive filter that reduces the effects of multipath in a received signal
- Determining means for determining whether or not the condition that the received signal deteriorates due to the change of the coefficient is satisfied
- the adaptive filter is:
- the mitigation apparatus further comprises update permission means for suppressing the coefficient update operation based on a determination result by the determination means.
- the determining means determines whether or not the received signal is overmodulated.
- the determination means includes modulation degree detection means for detecting a modulation degree from the frequency shift amount of the received signal, and comparison means for comparing the modulation degree with a predetermined frequency band. It is characterized by that.
- the determining means determines whether or not an overmodulation is caused based on a crosstalk countermeasure against an interference wave.
- an interference wave detecting means for detecting the presence or absence of an interference wave
- a band pass filter that limits a pass band of the received signal based on the jamming wave detected by the jamming wave detecting means
- the determination means includes a modulation degree detection means for detecting a modulation degree from a frequency shift amount of the received signal, and a comparison means for comparing the modulation degree with a pass band limited by the band pass filter. It is characterized by having.
- the determination means determines whether or not the received signal is overmodulated based on a signal changed according to a time constant.
- the determining means determines whether or not the electric field intensity of the received signal is an electric field intensity equal to or lower than a weak electric field.
- the determination unit includes an electric field information acquisition unit that acquires electric field strength information from the received signal, and a comparison unit that compares whether or not the electric field strength information is a weak electric field. It is characterized by.
- the determination means determines whether or not to perform antenna switching accompanying a diversity reception operation.
- the determination means determines whether or not the external signal has a force in the received signal.
- the present invention includes an adaptive filter that reduces the effects of multipath in a received signal
- Overmodulation determining means for determining whether or not overmodulation has occurred in the received signal; and weak electric field determining means for determining whether or not the electric field strength of the received signal is less than or equal to a weak electric field,
- the adaptive filter is:
- the mitigation apparatus includes an update permission unit that suppresses an update operation of the coefficient based on a determination result by one of the overmodulation determination unit and the weak electric field determination unit.
- the overmodulation determining means compares the modulation degree detecting means for detecting a modulation degree from the frequency shift amount of the received signal and the modulation degree and a passband limited by a bandpass filter.
- a first comparison means compares the modulation degree detecting means for detecting a modulation degree from the frequency shift amount of the received signal and the modulation degree and a passband limited by a bandpass filter.
- the weak electric field determination means includes electric field information acquisition means for acquiring electric field strength information from the received signal, and second comparison means for comparing whether or not the electric field strength information is a weak electric field.
- the present invention includes an antenna for receiving a signal
- Conversion means for converting the received signal into a digital signal
- An adaptive filter that reduces the effects of multipath on the received signal
- Determining means for determining whether or not the condition that the received signal deteriorates due to the change of the coefficient is satisfied The adaptive filter is:
- An update permission unit that suppresses an update operation of the coefficient based on a determination result by the determination unit.
- the present invention includes an antenna for receiving a signal
- Conversion means for converting the received signal into a digital signal
- An adaptive filter that reduces the effects of multipath on the received signal
- Overmodulation determining means for determining whether or not overmodulation has occurred in the received signal; and weak electric field determining means for determining whether or not the electric field strength of the received signal is less than or equal to a weak electric field,
- the adaptive filter is:
- An update permission unit that suppresses an update operation of the coefficient based on a determination result by one of the overmodulation determination unit and the weak electric field determination unit.
- the overmodulation determining means compares the modulation degree detecting means for detecting a modulation degree from the frequency shift amount of the received signal and the modulation degree and a passband limited by a bandpass filter.
- a first comparison means compares the modulation degree detecting means for detecting a modulation degree from the frequency shift amount of the received signal and the modulation degree and a passband limited by a bandpass filter.
- the weak electric field determination means includes electric field information acquisition means for acquiring electric field strength information from the received signal, and second comparison means for comparing whether or not the electric field strength information is a weak electric field.
- the present invention is a mobile receiver having the above-described mitigation device.
- the mobile receiver is used as an in-vehicle receiver.
- the mobile receiver is used as a portable receiver.
- the present invention provides a coefficient calculation step for calculating a coefficient for reducing the influence of multipath of a signal
- the mitigation method is characterized by comprising an update permission step for suppressing the coefficient update operation based on the determination result, and an update step for updating the coefficient based on the calculated coefficient.
- the present invention provides a coefficient calculation step for calculating a coefficient for reducing the influence of multipath of a signal
- An overmodulation determining step for determining whether or not the signal is overmodulated; a weak electric field determining step for determining whether or not the electric field strength of the signal is equal to or lower than a weak electric field;
- the mitigation method is characterized by comprising an update step for updating the coefficient based on the calculated coefficient.
- the overmodulation determining step includes a modulation degree detection step of detecting a modulation degree from the amount of frequency deviation of the signal, and a comparison between the modulation degree and a passband limited by a bandpass filter. It consists of 1 comparison step,
- the weak electric field determination step includes an electric field information acquisition step for acquiring electric field strength information from the signal, and a second comparison step for comparing whether or not the electric field strength information is a weak electric field.
- FIG. 1 is a block diagram showing a schematic configuration of a multinois noise reducing apparatus as an embodiment of the present invention.
- FIG. 2A and 2B show examples of side effects of distortion caused by ADF overmodulation in Figure 1.
- FIG. 3 is a block diagram showing a schematic configuration of a multipath noise reduction apparatus as another embodiment of the present invention.
- FIG. 4 is a block diagram showing a schematic configuration of a multi-noise reduction device as still another embodiment of the present invention.
- FIG. 5 is a block diagram showing a schematic configuration of a multi-noise reduction device as still another embodiment of the present invention.
- FIG. 6 is a block diagram showing a schematic configuration of a multi-noise reduction device as still another embodiment of the present invention.
- FIG. 7 is a block diagram showing a configuration in which the inverse function of the variable BPF filter function is used as the coefficient update method as the operation of the ADF in FIG.
- FIG. 8 is a graph showing the relationship between the IF signal and the variable BPF filter function G (f) in FIG.
- FIG. 9 is a waveform diagram showing a state in which the apparent envelope value as viewed from the ADF becomes constant by the correction value K in FIG.
- FIG. 10A is a waveform diagram showing a modulation degree detection signal output at the time of intermodulation from the modulation degree detector of FIG. 1 and the like, and FIG. 10B shows a state in which the modulation degree detection signal is changed according to a time constant.
- FIG. 10A is a waveform diagram showing a modulation degree detection signal output at the time of intermodulation from the modulation degree detector of FIG. 1 and the like, and FIG. 10B shows a state in which the modulation degree detection signal is changed according to a time constant.
- FIG. 11A is a waveform diagram showing the modulation degree detection signal output when multipath noise occurs from the modulation degree detector shown in FIG. 1, etc.
- FIG. 11B shows a state in which the modulation degree detection signal is changed according to the time constant.
- FIG. 12 is a waveform diagram showing the time change of the signal level of the IF signal.
- FIG. 13 is a graph showing that a singular point is generated in the relationship between the divided level and amplitude of the frequency deviation ⁇ due to modulation.
- FIG. 14 is a chart showing the ONZOFF judgment criteria for the ADF operation.
- FIG. 15 is a block diagram showing a configuration for turning on and off the ADF operation as shown in FIG.
- FIG. 16 is a schematic diagram of a multinois noise reducing apparatus as still another embodiment of the present invention. It is a block diagram which shows a rough structure.
- FIG. 17 is a graph showing the spectrum of external noise.
- FIG. 18A and FIG. 18B are diagrams showing a mobile receiver according to still another embodiment of the present invention.
- FIG. 19 is a block diagram showing a schematic configuration of a conventional multipath noise reduction apparatus.
- FIG. 20 is a block diagram showing a configuration for arithmetic processing for removing multipath distortion caused by the multipath effect from the FM signal in the ADF of FIG.
- FIG. 21 is a waveform diagram showing the relationship between the envelope error e (n) and the envelope signal env.
- FIG. 1 shows a schematic configuration of a multipath noise reduction device 20 which is a reduction device as an embodiment of the present invention.
- a multipath noise reduction device 20 provided in the reception device 23 includes an adaptive filter (hereinafter referred to as “ADF”) 21 and an overmodulation determination unit 22 as a determination unit.
- the ADF 21 basically operates as an adaptive filter similar to the ADF1 as shown in FIG.
- the receiving device 23 including the ADF 21 as the multipath noise reducing device 20 is modulated by frequency modulation (FM) or phase modulation (PM), and is used for receiving radio waves with a constant amplitude.
- FM frequency modulation
- PM phase modulation
- the received signal is converted from an analog signal to a digital signal by an analog Z-digital converter (hereinafter simply referred to as an AD converter) 24, and multipath noise is reduced by digital signal processing in the ADF21. And speak.
- the received signal whose multipath noise has been reduced by the ADF 21 is detected by the detector 25, and the modulated signal is demodulated.
- the multipath mitigation device 20 as described above can be realized by an arithmetic operation by a digital signal processor (DSP) except for the AD converter 24. DSP and AD conversion are combined into a semiconductor integrated circuit (IC).
- DSP digital signal processor
- the radio wave received by the receiving device 23 is, for example, an FM broadcast radio wave transmitted in a very high frequency (VHF) frequency band, received by an antenna (hereinafter abbreviated as “ANT”) 26, and depending on the electric field strength.
- VHF very high frequency
- ANT antenna
- a high frequency (RF) signal is output.
- the high frequency signal is processed in the analog signal state by an analog reception processing unit 27 having an RF unit for high frequency amplification and a MIX unit for frequency conversion.
- an intermediate frequency (IF) signal of about 10.7 MHz is received. It is output as a number.
- the IF signal is converted to a digital signal by AD conversion 24.
- the ADF 21 includes a variable filter unit 28 and a coefficient memory 29, which are update means, and a coefficient update permission means 32, which is update permission means, together with filter coefficient calculation means 30 and envelope calculation means 31, which are calculation means.
- the amplitude variation of the IF signal converted into the digital signal is detected by the envelope calculating means 31, and the filter coefficient is calculated by the filter coefficient calculating means 30 so as to correct the amplitude fluctuation, and is stored in the coefficient memory 29.
- the variable filter unit 28 uses the filter coefficient stored in the coefficient memory 29 to remove the multipath effect on the IF signal.
- coefficient update permission means 32 is provided, and the coefficient update operation is prohibited under conditions that cause side effects in the operation of ADF21.
- the coefficient update permission means 32 of the ADF 21 receives the determination result as to whether or not the coefficient update permission by the overmodulation determination means 22 is permitted.
- the IF signal input from the AD converter 24 to the ADF 21 is given a delay (D ELAY) by the delay means 33.
- the overmodulation determination means 22 includes a detector 34, a modulation degree detector 35 that is a modulation degree detection means, and a comparator 36 that is a comparison means.
- the detector 34 frequency-detects the IF signal of the digital signal converted by the AD conversion 24, and the modulation degree detector 35 detects the modulation degree from the frequency shift amount.
- the comparator 36 compares the detected modulation degree with a preset reference, and if the modulation degree exceeds the reference, it determines that the modulation is overmodulation and prohibits coefficient updating.
- the prohibition of coefficient update can be performed by setting a flag, for example.
- the filter coefficient calculation means 30 looks at the set flag and does not calculate a new coefficient. If the calculation of the coefficient has already been started, the calculation result is stored in the coefficient memory 9 and used for the filter operation in the variable filter unit 28 after the coefficient update prohibition. As a result, the variable filter unit 28 is fixed to the coefficient immediately after the coefficient update prohibition. Will be.
- the output of the delay means 33 may be directly input to the detector 25 by binning the ADF 21 that does not prohibit the coefficient update. In other words, at least suppress the effects of the adaptive filter operation.
- the degree of modulation of an FM-modulated radio signal can be expressed by comparing the frequency shift amount of the received signal with the standard frequency shift amount.
- a frequency shift of 75 kHz corresponds to a modulation degree of 100%.
- the reception frequency bandwidth is set to 150 kHz, for example, in order to avoid an influence on the reception signal. Therefore, even if overmodulation exceeding 100% occurs, the effect does not occur immediately.
- the modulation factor is close to 200%, the characteristics of the filter that determines the reception frequency band are not flat, and the influence of overmodulation increases.
- FIG. 2A and 2B show an example of the effect of multipath noise reduction by ADF21 and an example of the side effect of distortion deterioration during overmodulation.
- 2A shows the case where the ADF 21 is not operated
- FIG. 2B shows the case where the ADF 21 is operated.
- the multipath mitigation device 20 in Fig. 1 turns off the ADF operation when overmodulation is detected, thereby preventing multipath noise and the accompanying deterioration of distortion characteristics during overmodulation, and enabling both. Can do.
- FIG. 3 shows a schematic configuration of a multipath noise reduction device 40 which is a reduction device as another embodiment of the present invention.
- the multipath noise reduction device 40 provided in the reception device 43 includes an interference detection means 41 and an overmodulation judgment means 42 which is a judgment means instead of the overmodulation judgment means 22 of the multipath noise reduction device 20 of FIG. .
- the receiving device 43 including the multipath noise reduction device 40 limits the IF signal bandwidth by a variable bandpass filter (hereinafter abbreviated as “variable BPF”) 44 to prevent interference with adjacent interference waves. It can be carried out.
- the presence or absence of the adjacent interference wave is detected by the interference detection means 41.
- the interference detection means 41 is realized by a notch filter or the like that partially passes frequencies outside the maximum bandwidth of the receiving device 43.
- the variable BPF 44 can limit interference and prevent interference when adjacent interference is detected.
- Such a variable BPF 44 and the interference detection means 41 constitute an interference countermeasure block.
- the overmodulation determination means 42 includes a detector 34, a modulation degree detector 35, and a comparator 46 which is a comparison means.
- the comparator 46 uses the IF signal detected by the detector 34 after passing through the variable BPF 44 with reference to the cutoff frequency information Fc of the variable BPF 44 whose band is limited based on the adjacent interference wave detected by the interference detection means 41. It is determined whether or not the modulation degree of the signal detected by the modulation degree detector 35 is overmodulation. If it is determined that the signal is overmodulation, the operation of the ADF 21 is prohibited. That is, since the cutoff frequency information Fc changes depending on the state of adjacent interference, this Fc is detected.
- the overmodulation judging means 21 in FIG. 1 recognizes the overmodulation state from a comparison between the modulation degree of the desired signal and the bandwidth of the receiving device 23 that is known in advance, coefficient control that prohibits the operation of the ADF 21, etc.
- the bandwidth of the receiving device 43 changes. For example, it is assumed that the maximum bandwidth of the receiving device 43 is 150 kHz. 98.
- the modulation degree is 75kHzZviation.
- the jamming detection means 41 detects the jamming, and the variable BPF 44 performs an operation to narrow the bandwidth from 150 kHz to 50 kHz, for example.
- the desired signal is distorted due to the influence of the variable BPF 44.
- the ADF 21 is operated, the distortion further increases.
- the ADF control is performed by comparing the Fc information of the variable BPF44 and the modulation factor, it is possible to prevent the signal distortion from being worsened. Can be made compatible.
- BW control for narrowing the frequency band BW of the variable BPF 44 is performed.
- FIG. 4 shows a schematic configuration of a multipath noise reduction device 50 that is a reduction device according to still another embodiment of the present invention.
- a weak electric field determination means 52 as a determination means is used instead of the overmodulation determination means 21 of the multipath noise reduction device 20 of FIG.
- the receiving device 53 generates electric field strength information for automatic gain control (AGC) or the like by the analog reception processing unit 27 or the like.
- the weak electric field determination means 52 acquires the electric field strength information by the electric field information acquisition means 54, and
- the comparator 56 which is a stage, compares whether or not the electric field is weak.
- the weak electric field should be less than the electric field strength at which the envelope due to white noise is generated in the IF signal.
- the weak electric field determination means 52 performs control for prohibiting the operation of the ADF 21 when the electric field intensity is less than or equal to the weak electric field. As a result, when the electric field strength is weak, sometimes the ADF operation can be turned off, and both the reduction of multipath noise and the prevention of deterioration of the distortion characteristics in the weak electric field can be realized.
- FIG. 5 shows a schematic configuration of a multipath noise reduction device 60 which is a reduction device as still another embodiment of the present invention.
- the multipath noise reduction device 60 provided in the reception device 63 performs multipath noise reduction by combining diversity reception by switching between the main antenna (MAIN-ANT) and the sub-antenna (SUB-ANT).
- the diversity receiving unit 61 also functions the diversity control block 62 as diversity switching determination means that is determination means, and prohibits the operation of the ADF 21 at the time of switching.
- Diversity receiver 61 includes diversity control block 62, multipath detection block 64, electric field strength detection block 65, and antenna switching switch (hereinafter abbreviated as “ANT switching SW”) 6 6.
- the multipath detection block 64 detects the occurrence of multipath, and the electric field strength detection block 65 detects the electric field strength of the received radio wave.
- the ANT switching SW 6 6 is a switch for switching between the main antenna and the sub antenna, and switching is controlled by the diversity control block 62.
- the ADF21 In the diversity reception operation, a sudden change occurs in the IF signal input to the ADF21 at the timing of switching antennas. If the ADF 21 reacts to this and updates the coefficients, signal distortion and abnormal noise will occur. For this reason, the ADF21 operation is prohibited at the timing of switching operation in diversity reception such as antenna switching. As a result, it is possible to achieve both the reduction of multipath noise and the prevention of deterioration of the distortion characteristics in a weak electric field.
- FIG. 6 shows a schematic configuration of a multipath noise reduction device 70 which is a reduction device as still another embodiment of the present invention.
- the condition determining means 72 combining the overmodulation determining means 42 in the multipath noise reducing device 40 in FIG. 3 and the weak electric field determining means 52 in FIG. including. That is, the overmodulation judging means 42 includes a detector 34, a modulation degree detector 36 which is a modulation degree detection means, and a first comparison means. And a comparator 46 which is a stage.
- the weak electric field determination unit 52 includes an electric field information acquisition unit 54 and a comparator 56 which is a second comparison unit.
- the condition judging means 72 judges the logical sum (OR) of the judgment results of the overmodulation and the weak electric field by the comparators 46 and 56 by the OR circuit 73, and prohibits the operation of the ADF 21 based on the judgment result. If either overmodulation or weak electric field is established, the operation of ADF21 is prohibited, so more accurate control can be realized.
- Figure 7 shows the configuration of using the inverse function of the filter function of variable BPF44 as the coefficient update method as the operation of ADF21.
- Overmodulation distortion is generated by variable BPF44, which is a variable IF filter for removing adjacent interference.
- variable BPF44 is a variable IF filter for removing adjacent interference.
- the envelope calculating means 80 calculates this amplitude change.
- the filter coefficient calculation means 81 calculates the correction value K as 1 / F (I ⁇ I). ⁇ is detected by the modulation degree detecting means 82.
- F is the inverse function of the filter function G of variable BPF44.
- Figure 8 shows the relationship between the IF signal and the filter function G (f) of the variable BPF44.
- FIG. 9 shows a state where the apparent envelope value as viewed from the ADF 21 is constant by the correction value K.
- FIG. 10A, FIG. 10B, FIG. 11A, and FIG. 11B show states in which the modulation degree detection signal output from the modulation degree detector 35 is changed according to the time constant to prevent erroneous detection.
- Figure 10B shows how long it takes for the coefficient update control signal that inhibits the ADF21 operation to rise to the threshold Vth when the overmodulation detection signal during overmodulation shown in Figure 10A is changed according to the time constant. This indicates that the coefficient update control signal is turned ON even if applied.
- the modulation degree detection signal at the time of occurrence of multipath noise shown in FIG. 11A is a short time, so even if the modulation degree detection signal is changed according to the time constant, it does not rise to the threshold value Vth.
- the coefficient update control signal continues to be turned off, the ADF21 operation is not prohibited, and multipath noise reduction continues.
- the modulation degree detector 35 performs overmodulation detection using the maximum value (MAXHOLD) of the FM detection signal level.
- MAXHOLD the maximum value of the FM detection signal level.
- the modulation degree detection signal is changed according to the time constant to distinguish between overmodulation and multipath noise.
- the generation time of the modulation degree detection signal becomes longer, so that overmodulation can be sufficiently detected even if the modulation degree detection signal is changed according to the time constant.
- the present invention it is possible to determine when the electric field suddenly changes and when multipath noise occurs, and prohibit the operation of the ADF 21 when the electric field suddenly changes.
- the method of distinguishing between the sudden change of electric field and the occurrence of multipath noise is based on the presence or absence of correlation between amplitude and modulation.
- the presence or absence of a singular point of the amplitude of the IF signal with respect to the modulation degree (frequency deviation) can be used.
- FIG. 12 shows the time change of the frequency deviation ⁇ of the signal detected from the IF signal. Divide the frequency deviation ⁇ ⁇ by dividing the amplitude into multiple levels LI, L2, ⁇ , L-l, L- 2, ⁇ .
- FIG. 13 shows that a singular point occurs in the relationship between the divided level and amplitude of the frequency deviation ⁇ due to modulation.
- a singular point is detected as a point where, for example, the amplitude is differentiated by a frequency shift and a large change occurs to some extent or the sign is reversed.
- Figure 14 shows the ONZOFF criteria for ADF21 operation. If there is a fluctuation in amplitude and there is a singular point, multipath noise is generated and ADF21 is turned ON. If there is a fluctuation in amplitude and there is no singular point, it is judged that the electric field suddenly changes, and the ADF21 operation is turned off and prohibited. If there is no amplitude fluctuation, the ADF21 operation is turned off.
- FIG. 15 shows a configuration for turning on and off the operation of the ADF 21 as shown in FIG.
- Electric field sudden change determination means 91 includes amplitude detection means 92, high-pass filter (HPF) 93, fluctuation detection means 94, and FM detector 95.
- the amplitude detection means 92 detects the amplitude of the IF signal based on, for example, the S meter signal.
- the high-pass filter 93 passes the high-frequency component, and the fluctuation detecting means 94 detects the fluctuation.
- the FM detector 95 detects the IF signal and detects the frequency shift ⁇ ⁇ .
- the frequency deviation ⁇ ⁇ is divided into multiple levels such as La, Lb, Lc, etc., and ⁇ ⁇ dividing means 95a, 95b, 95c are divided into ij, and registers 97a, 97b, 97c are respectively stored in the yarn. Detect singularity based on amplitude. Fluctuation detection means 94 detects fluctuations and singularity The AND circuit 99 determines that the detection means has detected a singular point, and performs the multi-pass operation as shown in FIG. The singularity detection means 98 detects level singularities stored in the registers 97a, 97b, and 97c.
- FIG. 16 shows a schematic configuration of a multipath noise reduction device 100 which is a reduction device as still another embodiment of the present invention.
- multinois noise reducing apparatus 100 provided in receiving apparatus 103, when external noise determining means 102, which is a determining means, determines that external noise is mixed in the IF signal, the operation of ADF 21 is prohibited.
- external noise may be mixed together with the target radio wave.
- the external noise determination means 102 includes a SideSpectrum part extraction filter 104 and a comparison Z control flag generation part 105. Since the frequency components of the external noise are present in the entire band, the detection of the external noise mixed in the IF signal is performed by extracting the SideSpectrum portion other than A fmax to A fmax shown in FIG.
- FIG. 18B is a diagram showing a mobile receiver as yet another embodiment of the present invention.
- the mobile receiver includes receivers 23, 43, 53, 63, 73 including multipath noise reduction devices 20, 40, 50, 60, 70, 100 having the ADF 21, as shown in the above-described embodiment. , 103.
- Examples of the mobile receiver include an in-vehicle receiver shown in FIG.
- Such a mobile receiver is susceptible to multipath noise. Therefore, such a mobile receiver that is easily affected by multipath noise is used as a receiver 23, 4 3 provided with the mano retinois noise reducer 20, 40, 50, 60, 70, 100 of the present invention. , 53, 63, 73, and 103, it is possible to compensate for the technical and performance disadvantages of the conventional method for reducing multipath noise using an adaptive filter, and to receive radio signals comfortably. .
- the mitigation device comprises an adaptive filter and includes a determination means.
- the adaptive filter is a variable filter that detects the amplitude fluctuation of the received signal in order to reduce the effects of multipath that occurs in the propagation process of the radio wave when receiving the radio wave of the modulation method that does not change the amplitude.
- the filter coefficient is updated so as to suppress the amplitude fluctuation.
- the judging means judges whether or not a condition that the received signal is deteriorated by changing the coefficient of the adaptive filter is satisfied.
- the update permission means suppresses the coefficient update operation based on the determination result of the determination means, so that the technical and performance disadvantages of the conventional method for reducing multipath noise by the adaptive filter are compensated, and the radio wave signal is comfortable. It is possible to receive the
- the determination means determines whether or not the received signal is overmodulated. Based on the determination result, the update permission means suppresses the coefficient update operation. This makes it possible to comfortably receive radio wave signals by compensating for technical and performance deficiencies in the conventional method for reducing multipath noise using adaptive filters.
- the determination as to whether or not the overmodulation is generated by the determination means is performed based on a comparison between the modulation degree and a predetermined frequency band. It can be determined whether or not.
- the determination as to whether or not the overmodulation is generated by the determination means is performed based on a comparison between the modulation degree and the passband limited by the bandpass filter. It is possible to determine whether or not the power is.
- the determination of overmodulation by the determination means is performed based on the signal changed according to the time constant, so that the determination is not sensitive and erroneous detection can be prevented. Overmodulation If this occurs, the modulation level detection signal will continue for a long period of time compared to multipath noise, so even if the modulation level detection signal is changed according to the time constant, sufficient overmodulation will be detected. This is possible, and the effect of suppressing the operation of the adaptive filter can be sufficiently obtained.
- the operation of the adaptive filter is suppressed even at the time of over-modulation and at the time of a weak electric field.
- the operation of the adaptive filter is performed. Therefore, it is possible to compensate for the technical and performance disadvantages of the conventional method for reducing multipath noise using an adaptive filter, and to receive radio signals comfortably.
- the determination unit when the diversity reception operation is performed, the determination unit satisfies the condition that the received signal is deteriorated due to the change of the coefficient of the adaptive filter depending on whether or not switching is performed in accordance with the diversity reception operation. If it is determined whether or not there is switching, the operation of the adaptive filter is suppressed, so the technical and performance disadvantages of the conventional method of reducing multipath noise by the adaptive filter are compensated, and the signal of the radio wave is comfortably It can be received.
- the determination means determines whether or not a predetermined condition for deteriorating the received signal is satisfied by changing the coefficient of the adaptive filter based on whether or not the external noise is generated, and generating the external noise. If it is judged that there is, the operation of the adaptive filter is suppressed, so that it is possible to compensate for the technical and performance disadvantages of the conventional method for reducing multipath noise by the adaptive filter and to receive the radio wave signal comfortably.
- the mitigation device includes an adaptive filter and includes overmodulation determination means and weak electric field determination means.
- the adaptive filter is a variable filter that detects the amplitude fluctuation of the received signal in order to reduce the multipath effect that occurs in the propagation process of the radio wave when receiving the radio wave of the modulation method that does not change the amplitude.
- the filter coefficient is updated so as to suppress amplitude fluctuation.
- the overmodulation determining means determines whether or not the received signal is overmodulated, and the weak electric field determining means determines that the electric field strength of the received signal is less than the weak electric field. It is determined whether or not the electric field strength.
- the first comparing means compares the degree of modulation detected by the degree of modulation detecting means with the passband limited by the bandpass filter.
- the second comparison means determines whether or not the electric field strength information of the received signal strength acquired by the electric field information acquisition means is a weak electric field.
- the update permission unit suppresses the coefficient update operation based on the determination result of either the overmodulation determination unit or the weak electric field determination unit, so that more accurate control is possible and multipath noise is reduced by an adaptive filter. This makes it possible to compensate for the technical and performance disadvantages of the conventional method and to receive radio signals comfortably.
- the receiving apparatus converts the signal received by the antenna into a digital signal by the converting means, and performs digital signal processing using the adaptive filter.
- the judging means judges whether or not a condition that the received signal is deteriorated by changing the coefficient of the adaptive filter is satisfied.
- the update permission unit suppresses the coefficient update operation based on the determination result of the determination unit. Therefore, the update permission unit compensates for the technical and performance disadvantages of the conventional method in the multipath noise reduction by the adaptive filter, and the radio wave signal.
- the receiving apparatus converts the signal received by the antenna into a digital signal by the converting means, and performs digital signal processing using an adaptive filter.
- the overmodulation determining means determines whether or not the received signal is overmodulated, and the weak electric field determining means determines whether or not the electric field strength of the received signal is equal to or lower than the weak electric field.
- the first comparing means compares the modulation degree detected by the modulation degree detecting means with the passband limited by the bandpass filter.
- the second comparison means determines whether or not the electric field strength information from the received signal acquired by the electric field information acquisition means is a weak electric field.
- the update permission means suppresses the coefficient update operation based on the judgment result of either the overmodulation judgment means or the weak electric field judgment means, thus enabling more accurate control and reducing multipath noise with an adaptive filter. This makes it possible to compensate for the technical and performance disadvantages of the conventional method and to receive radio signals comfortably.
- the mobile receiver includes the above-described mitigation device, It is easily affected by path noise. It can be used favorably in in-vehicle receivers or portable receivers, and it compensates for technical and performance disadvantages of conventional methods in reducing multipath noise using adaptive filters. It is possible to realize a mobile receiver that can comfortably receive the signal.
- the determination step it is determined whether or not the force that satisfies the condition that the signal is deteriorated by the change of the coefficient is satisfied. If it is determined that the condition is satisfied, the update operation is suppressed in the update permission step. Therefore, it is possible to compensate for the technical and performance disadvantages of the conventional method for reducing multipath noise and to receive radio wave signals comfortably.
- the overmodulation determining step it is determined whether or not the signal is overmodulated.
- the weak electric field determining step whether or not the electric field strength of the signal is equal to or lower than the weak electric field. Judging.
- the first comparison step compares the modulation degree detected in the modulation degree detection step with the passband limited by the bandpass filter.
- the weak electric field determination step determines whether the electric field strength information of the signal force acquired in the electric field information acquisition step is a weak electric field.
- the update permission step the coefficient update operation is suppressed based on the determination result of either the overmodulation determination step or the weak electric field determination step. Therefore, more accurate control becomes possible, and the technical and performance disadvantages of the conventional method for reducing multipath noise can be compensated, and radio wave signals can be received comfortably.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Power Engineering (AREA)
- Noise Elimination (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
- Radio Transmission System (AREA)
Abstract
Description
Claims
Priority Applications (4)
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US11/887,343 US20090202024A1 (en) | 2005-03-31 | 2006-03-29 | Reducing Apparatus and Method, and Receiving Apparatus |
EP06730534A EP1865607B1 (en) | 2005-03-31 | 2006-03-29 | Reducing apparatus and method, and receiving apparatus |
CN2006800106688A CN101151808B (zh) | 2005-03-31 | 2006-03-29 | 衰减装置及方法、信号接收装置 |
KR1020077025120A KR100982707B1 (ko) | 2005-03-31 | 2006-03-29 | 경감 장치 및 방법, 그리고 수신 장치 |
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JP2005-105365 | 2005-03-31 | ||
JP2005105365A JP4230470B2 (ja) | 2005-03-31 | 2005-03-31 | 軽減装置および方法、ならびに受信装置 |
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US (1) | US20090202024A1 (ja) |
EP (1) | EP1865607B1 (ja) |
JP (1) | JP4230470B2 (ja) |
KR (1) | KR100982707B1 (ja) |
CN (1) | CN101151808B (ja) |
WO (1) | WO2006106788A1 (ja) |
Cited By (2)
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EP2053753A2 (en) * | 2007-10-24 | 2009-04-29 | Sanyo Electric Co., Ltd. | FM receiver |
CN101527578A (zh) * | 2008-01-28 | 2009-09-09 | 恩益禧电子股份有限公司 | 自适应均衡器和自适应均衡方法 |
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JP4987843B2 (ja) * | 2007-12-28 | 2012-07-25 | パナソニック株式会社 | 位相誤差検出装置、波形整形装置及び光ディスク装置 |
JP5095444B2 (ja) * | 2008-03-04 | 2012-12-12 | パイオニア株式会社 | フィルタ装置、受信装置及び信号処理方法 |
CN101960724B (zh) * | 2008-03-11 | 2013-07-24 | 三菱电机株式会社 | 无线接收装置 |
GB2481237A (en) * | 2010-06-17 | 2011-12-21 | Nokia Corp | Protecting a speaker arrangement against over-modulated broadcasts |
US10181315B2 (en) * | 2014-06-13 | 2019-01-15 | Cirrus Logic, Inc. | Systems and methods for selectively enabling and disabling adaptation of an adaptive noise cancellation system |
DE112016007003B4 (de) * | 2016-06-24 | 2019-09-12 | Mitsubishi Electric Corporation | Funkempfangsvorrichtung |
DE102017209209A1 (de) * | 2017-05-31 | 2018-12-06 | Laird Dabendorf Gmbh | Signalkopplungsvorrichtung und Verfahren zum Betrieb einer Signalkopplungsvorrichtung |
US11025358B1 (en) | 2020-04-20 | 2021-06-01 | Bae Systems Information And Electronic Systems Integration Inc. | Method of adaptively mitigating common template multi-channel wireless interference |
US11394414B2 (en) * | 2020-04-20 | 2022-07-19 | Bae Systems Information And Electronic Systems Integration Inc. | Method of wireless interference mitigation with efficient utilization of computational resources |
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- 2006-03-29 EP EP06730534A patent/EP1865607B1/en not_active Expired - Fee Related
- 2006-03-29 CN CN2006800106688A patent/CN101151808B/zh not_active Expired - Fee Related
- 2006-03-29 US US11/887,343 patent/US20090202024A1/en not_active Abandoned
- 2006-03-29 KR KR1020077025120A patent/KR100982707B1/ko not_active IP Right Cessation
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EP2053753A2 (en) * | 2007-10-24 | 2009-04-29 | Sanyo Electric Co., Ltd. | FM receiver |
EP2053753A3 (en) * | 2007-10-24 | 2011-07-06 | Sanyo Electric Co., Ltd. | FM receiver |
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Also Published As
Publication number | Publication date |
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US20090202024A1 (en) | 2009-08-13 |
JP2006287654A (ja) | 2006-10-19 |
CN101151808A (zh) | 2008-03-26 |
CN101151808B (zh) | 2011-05-25 |
KR100982707B1 (ko) | 2010-09-17 |
JP4230470B2 (ja) | 2009-02-25 |
EP1865607A1 (en) | 2007-12-12 |
KR20070118160A (ko) | 2007-12-13 |
EP1865607A4 (en) | 2011-05-04 |
EP1865607B1 (en) | 2012-04-25 |
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