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WO2001011844A1 - Demodulateur orthogonal et procede de demodulation orthogonale - Google Patents

Demodulateur orthogonal et procede de demodulation orthogonale Download PDF

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Publication number
WO2001011844A1
WO2001011844A1 PCT/JP2000/004486 JP0004486W WO0111844A1 WO 2001011844 A1 WO2001011844 A1 WO 2001011844A1 JP 0004486 W JP0004486 W JP 0004486W WO 0111844 A1 WO0111844 A1 WO 0111844A1
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WIPO (PCT)
Prior art keywords
signal
amplitude
quadrature
phase
delay time
Prior art date
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Ceased
Application number
PCT/JP2000/004486
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English (en)
Japanese (ja)
Inventor
Akihiro Okazaki
Hiroshi Kubo
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP2001515598A priority Critical patent/JP3522725B2/ja
Priority to AU58485/00A priority patent/AU5848500A/en
Priority to TW089113737A priority patent/TW484286B/zh
Publication of WO2001011844A1 publication Critical patent/WO2001011844A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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
    • H04L27/389—Demodulator circuits; Receiver circuits with separate demodulation for the phase and amplitude components

Definitions

  • the present invention relates to a quadrature demodulator used for a receiver of a car telephone or the like, and more particularly, to a quadrature demodulator and a quadrature demodulation method applicable even when a reception level fluctuates greatly due to fading or the like. It is. Background art
  • the transmitting side modulates a baseband signal into a high-frequency signal (carrier) and sends the signal to the receiving side.
  • a delay that cannot be ignored for data symbols may occur due to multipath propagation. Therefore, in such an environment, intersymbol interference occurs across the code symbols, and it is necessary to use an adaptive equalizer on the receiving side to overcome the intersymbol interference.
  • an adaptive equalizer it is necessary to realize a quadrature detector on the receiving side and accurately reproduce amplitude information. In this case, when the reception level fluctuates greatly due to fusing or the like, A high-precision automatic gain control (AGC) circuit is required.
  • AGC automatic gain control
  • FIG. 10 is a diagram showing a configuration of a conventional quadrature signal demodulator (hereinafter, referred to as a quadrature demodulator) described in the publication No. 274485336 having such features.
  • 1 is a reception signal input terminal, and 2 is a judgment value output terminal.
  • 100 is a band limiting filter
  • 5 is a logarithmic amplifier
  • 101 is a filter
  • 7 is a phase detection circuit
  • 102 is a quantization circuit
  • 1 is a level detection circuit.
  • 12 is a polar coordinate orthogonal coordinate conversion circuit
  • 14 is a demodulation circuit.
  • the band limiting filter 100 extracts only a specific frequency component having a signal component from the received modulated signal.
  • the logarithmic amplifier 5 outputs a logarithmic conversion value of an envelope amplitude component and a signal component whose amplitude is suppressed (indicating a known logarithmic conversion (Log conversion)) from the reception signal extracted by the band limitation.
  • the phase detection circuit 7 extracts the phase component of the signal from the signal component whose amplitude has been suppressed.
  • the quantization circuit 102 the logarithmically converted value is once passed through the filter 101 and then quantized.
  • the level detection circuit 11 receives the quantized logarithmic conversion value and detects the amplitude level of the signal.
  • the polar orthogonal coordinate conversion circuit 12 performs antilogarithmic conversion based on the detected amplitude level to make the quantized logarithmic conversion value an appropriate value, and further inputs a phase component to obtain the orthogonality. Convert to coordinate signals.
  • the demodulation circuit 14 receives the signal converted to the rectangular coordinates and performs demodulation processing.
  • FIG. 11 is a diagram illustrating an example of a received modulated signal. More specifically, the signal when the band is limited by the band-limiting filter 100 is shown on the frequency axis.
  • the band-limiting filter 100 realizes two functions of waveform shaping and aliasing prevention. In this case, the band limiting filter 100 needs to be a steep filter, and the sampling frequency can be made relatively small.
  • FIG. 12 is also a diagram showing an example of a received modulated signal, similarly to FIG. 11, and the difference is that a frequency deviation is applied.
  • the band limiting filter 100 since the band limiting filter 100 has a steep characteristic, the relative shift between the spectrum of the received signal and the frequency characteristic of the band limiting filter 100 is large.
  • the logarithmic conversion value of the envelope amplitude component is obtained from the reception signal extracted by the band limitation, the logarithmic conversion value is passed through a filter, and then quantization is performed. At this time, if there is a frequency shift in the spectrum of the received signal, frequency correction is performed before quantization. Then, the amplitude level of the signal is calculated from the quantized logarithm And performs antilogarithmic transformation on the basis of the amplitude level to make the quantized logarithmic transformed value an appropriate value. Finally, the phase components extracted earlier are input into a signal of orthogonal coordinates, and demodulation is performed using the signal converted into the orthogonal coordinates.
  • the quadrature demodulator described in the above-mentioned document has a problem that it is extremely difficult to realize steep characteristics using an analog filter that can be realized with a simple configuration.
  • the received signal includes a frequency deviation as shown in FIG. 12, and even if the frequency is corrected in a precise manner, a significant characteristic deterioration occurs.
  • FIG. 13 is a diagram in which a signal component having a frequency deviation is band-limited as shown in FIG. 12, and then the frequency is corrected, and the result is expressed on a frequency axis.
  • the desired signal component is largely removed, and further, the aliasing component of the signal is mixed as interference.
  • frequency correction is performed by a demodulation circuit, it is necessary to multiply a complex received signal by a complex phase correction value, and there is a problem that an increase in the circuit scale for the frequency correction is unavoidable. .
  • FIG. 14 is a diagram in which the signal component and the quantization noise are expressed together on the frequency axis in the quantization performed by the quantization circuit. Since the logarithm conversion value is very wide and the signal amplitude in the range is compressed, if the quantization number is small again when returning to an exact number using a fe-target orthogonal coordinate conversion circuit, this exact value The quantization noise present inside cannot be ignored.
  • the signal of the rectangular coordinates output from the polar coordinate rectangular coordinate conversion circuit disappears in a section where the amplitude of the received signal is small.
  • the amplitude of the orthogonal coordinate signal becomes 0 due to the quantization error due to the non-linear compression of the received signal. That is, if the thermal noise is small In this case, the correct phase component can be extracted by the phase detection circuit. At this time, if the amplitude is 0, the correctly extracted phase information is lost in the signal of the rectangular coordinates.
  • the demodulation characteristics are deteriorated under the condition that demodulation can be performed only by the phase information.
  • the signal amplified by the non-linear function and the signal whose amplitude is limited pass through different amplification systems. That is, the two signals have different delay times. Therefore, if the difference in the delay time is large, the timing of the amplitude information and the phase information in the polar rectangular coordinate conversion circuit will be greatly shifted, and the reproduced rectangular coordinate signal will be distorted. There was a problem that deterioration occurred.
  • FIG. 15 is a diagram showing a first problem in the level detection circuit.
  • FIG. 16 is a diagram showing a second problem in the level detection circuit.
  • a method of performing level detection after receiving all signals is shown. The stable signal can be reproduced in the entire burst, but the signal output has a large delay.
  • the present invention has been made in view of the above, and provides a quadrature demodulator and a quadrature demodulation method capable of always realizing optimum demodulation characteristics even when a reception level fluctuates greatly due to fading or the like. It is an object. Disclosure of the invention
  • the reception signal modulated to a high frequency is configured to be demodulated into an in-phase component and a quadrature component, and the signal component is not folded back when quantization is performed.
  • An anti-aliasing filtering means (corresponding to an anti-aliasing filter 4 in an embodiment described later) for applying band limitation to a signal with moderate characteristics, and a signal amplified according to a nonlinear function based on the band-limited signal.
  • a non-linear amplifying means (corresponding to a logarithmic amplifier 5) for generating a signal whose amplitude is limited to enable phase detection, and a phase detecting means (corresponding to a phase detecting circuit 7) for detecting phase information from the amplitude-limited signal.
  • Phase reverse rotation means for performing a phase reverse rotation process based on the phase information and the frequency deviation information given to the received signal (corresponding to the phase reverse rotation circuit 9)
  • An over-sampling quantization means (corresponding to an over-sampling quantization circuit 6) for quantizing the amplified signal at a speed faster than a symbol rate, and a level detection means (detecting an amplitude reference level from the quantized signal).
  • a level detection means detecting an amplitude reference level from the quantized signal.
  • Polar coordinate orthogonal coordinate conversion means (corresponding to a polar coordinate orthogonal coordinate conversion circuit 12) for converting the signal after the amplitude correction into an in-phase component and an orthogonal component corresponding to an oversample rate using the processed signal.
  • digital filtering means (corresponding to digital filter 13) for performing band limitation on the in-phase component and the quadrature component. It is characterized by having.
  • the band-limiting filter does not need to have steep characteristics, and the function of the band-limiting filter can be easily replaced with an analog filter having a moderate characteristic.
  • the circuit is simplified. it can. Also, by relaxing the characteristics of the anti-aliasing filtering means, it is possible to avoid significant characteristic deterioration even if the received signal has a frequency deviation. Also, by applying the phase reverse rotation to the phase detection value, the circuit scale does not increase due to the arithmetic processing.
  • the quantization error when performing antilogarithmic transformation on the amplitude value generated due to the quantization of the logarithmically transformed value is high due to the quantization performed at a high frequency and the digital finolator. It can be suppressed by accurate filtering processing.
  • timing control means for controlling the operation timing of the level detection means by receiving timing information serving as a reference for detecting the amplitude reference level from outside. (Corresponding to the timing control circuit 10).
  • the level detection period is reduced, and the delay amount of the received signal is reduced.
  • the quadrature demodulator according to the next invention comprises buffer means for accumulating the quantized signal and the phase information, and controlling the timing to control an amplitude reference level from the signal accumulated in the buffer means. Is detected. According to the present invention, even when a transient response occurs at the rise of the signal level and the beginning of the burst cannot be used, the transient state can be absorbed by the delay for accumulation in the buffer means, and the preamble is provided at the beginning of the burst Eliminates the need.
  • the quadrature demodulator according to the next invention is characterized in that it can be extended to diversity reception for receiving modulated signals from a plurality of antennas.
  • the polar coordinate orthogonal transformation means performs nonlinear correction in addition to the conversion processing by the inverse function of the nonlinear function.
  • the present invention furthermore, by using the polar coordinate orthogonal transformation means having the above-mentioned conversion characteristics, even when the reception signal falls, that is, even in a section where the amplitude of the reception signal is small, the extracted phase information can be obtained. Loss can be prevented.
  • the quadrature demodulator according to the next invention further comprises: a delay time correcting unit that corrects a delay time difference between the signal amplified according to the nonlinear function and the amplitude-limited signal.
  • the delay time correction means adjusts the delay time of the signal whose amplitude is limited by adjusting the timing of the signal input to the phase detection means or the phase detection. This makes it possible to make adjustments before the discretization, making it possible to make fine adjustments to the quantization speed. Further, as another adjustment method, for example, a delay time correction unit performs processing on a signal discretized at a quantization speed. This allows for a wide range of delay time adjustments.
  • the signal component in the process of demodulating a received signal modulated to a high frequency into an in-phase component and a quadrature component, the signal component is not turned back when performing quantization.
  • a fourth step a fifth step of quantizing the amplified signal at a rate faster than a symbol rate, a sixth step of detecting an amplitude reference level from the quantized signal, and By using the signal and the amplitude reference level, performs amplitude correction by performing conversion processing by the inverse function of the nonlinear function, furthermore, it performed the phase reverse rotation processing
  • a process comprising the steps of:
  • a steep characteristic is not required for the band-limiting filter, and the function of the band-limiting filter can be easily replaced with an analog filter having a moderate characteristic. Further, by mitigating the characteristics in the first step, even if the received signal has a frequency deviation, significant characteristic deterioration is avoided. Also, by applying the phase reverse rotation to the detected phase value, the circuit scale does not increase due to the arithmetic processing.
  • the level detection period is extended, and the amount of delay of the received signal is reduced.
  • the quadrature demodulation method includes a tenth step of accumulating the quantized signal and the phase information, and the timing is controlled to accumulate in the tenth step.
  • the amplitude reference level is detected from the signal.
  • the transient state can be absorbed by the delay in the 10th step, and a preamble must be provided at the beginning of the burst. Disappears.
  • a quadrature demodulation method is characterized in that it can be extended to diversity reception for receiving modulated signals from a plurality of antennas.
  • the present invention it is possible to perform demodulation processing with higher accuracy by extending to diversity reception that receives modulated signals from a plurality of antennas.
  • nonlinear correction is performed in addition to conversion processing by an inverse function of the nonlinear function. I do.
  • the present invention by further executing the seventh step having the above conversion characteristic, loss of the extracted phase information is prevented even when the reception signal falls, that is, even in a section where the amplitude of the reception signal is small. be able to.
  • the quadrature demodulation method according to the next invention further includes a first step of correcting a delay time difference between the signal amplified according to the nonlinear function and the amplitude-limited signal. It is characterized by.
  • the delay time of the signal whose amplitude is limited is adjusted by adjusting the timing of the signal input to the phase detection circuit or the phase detection. This makes it possible to make adjustments before the discretization, and to make fine adjustments to the quantization speed. Further, as another adjustment method, for example, in the first step, processing is performed on a signal discretized at a quantization speed. This allows for a wide range of delay time adjustments.
  • FIG. 1 is a diagram showing a configuration of a first embodiment of a quadrature demodulator according to the present invention.
  • FIG. 2 is a diagram showing an example in which a received modulated signal is sampled. The figure shows an example of ⁇ sampled from the received modulated signal, and Fig. 4 shows that the signal component with frequency deviation is band-limited, then the frequency is corrected, and it is expressed on the frequency axis.
  • FIG. 5 is a diagram showing signal components and quantization noise on a frequency axis
  • FIG. 6 is a diagram showing a configuration of a quadrature demodulator according to a second embodiment of the present invention.
  • FIG. 1 is a diagram showing a configuration of a first embodiment of a quadrature demodulator according to the present invention.
  • FIG. 2 is a diagram showing an example in which a received modulated signal is sampled. The figure shows an example of ⁇ sampled from the received modulated signal, and Fig. 4 shows that the signal component with frequency deviation is band-limited
  • FIG. 7 is a diagram illustrating a process of detecting a logarithmically converted value based on external timing information
  • FIG. 8 is a diagram illustrating a conversion process characteristic in a polar coordinate orthogonal coordinate conversion circuit
  • FIG. 9 shows the configuration of the quadrature demodulator according to the fourth embodiment of the present invention.
  • FIG. 10 is a diagram showing a configuration of a conventional quadrature demodulator described in the publication of No. 2 748 5 36
  • FIG. 11 is an example of a received modulated signal.
  • FIG. 12 is a diagram illustrating an example of a received modulated signal
  • FIG. 13 is a diagram illustrating an example of a received modulated signal.
  • FIG. 14 is a diagram in which signal components having frequency deviations are band-limited and then subjected to frequency correction, which is expressed on the frequency axis.
  • Fig. 14 shows the signal components and quantization noise expressed on the frequency axis.
  • FIG. 15 is a diagram showing a first problem in the level detection circuit
  • FIG. 16 is a diagram showing a second problem in the level detection circuit.
  • FIG. 1 is a diagram showing a configuration of a quadrature demodulator according to a first embodiment of the present invention.
  • FIG. 1 is a diagram showing a configuration of a quadrature demodulator according to a first embodiment of the present invention.
  • 1, 1 is a reception signal input terminal, 2 is a judgment value output terminal, 4 is an anti-aliasing filter, 5 is a logarithmic amplifier, 6 is an over-one-sample quantization circuit, Reference numeral 7 denotes a phase detection circuit, 9 denotes a phase reverse rotation circuit, 11 denotes a level detection circuit, 12 denotes a polar coordinate orthogonal coordinate conversion circuit, 13 denotes a digital filter, and 14 denotes a demodulation circuit. It is.
  • the received signal is band-limited and extracted to such an extent that aliasing noise does not occur in the oversample quantization circuit 6 in the subsequent stage.
  • the filter used here is a known analog filter power S.
  • the received signal power extracted by the band limitation, the logarithmic conversion value of the envelope amplitude component, and the signal component whose amplitude is suppressed are used. And are output.
  • the phase detection circuit 7 extracts the phase component of the signal from the signal component whose amplitude has been suppressed, and the phase reverse rotation circuit 9 further applies a frequency from the outside such as the demodulation circuit 14 to the extracted phase component. Performs phase rotation according to the deviation instruction, and outputs the value after phase rotation.
  • the over-one-sample quantization circuit 6 quantizes the logarithm conversion value at a speed higher than the symbol rate.
  • the level detection circuit 11 receives the quantized logarithmically converted value and detects the amplitude level of the signal.
  • the polar coordinate orthogonal coordinate conversion circuit 12 performs antilogarithmic conversion to make the logarithmically converted value quantized at the speed of oversampling an appropriate value, and further performs phase inversion.
  • the phase component that has been subjected to the rotation processing is converted into a signal of rectangular coordinates corresponding to the speed of oversampling.
  • the digital filter 13 inputs the signal converted to the rectangular coordinates of over one sample rate to perform waveform shaping, and the demodulation circuit 14 inputs the waveform shaped signal to perform demodulation processing. Do.
  • the configuration of the present embodiment has the following four features.
  • FIG. 2 is a diagram illustrating an example of a case where a received modulated signal is sampled. Specifically, the signal whose band is limited by the anti-aliasing filter 4 is shown on the frequency axis.
  • the anti-aliasing filter 4 used here does not have a waveform shaping function, but only realizes an anti-aliasing function. In this case, since the anti-aliasing filter 4 does not need to be a steep filter, desired characteristics can be easily realized with a known analog filter (first feature). As a result, the circuit can be simplified.
  • FIG. 3 is also a diagram showing an example of a case where a received modulated signal is sampled, as in FIG. 2, and the difference is that a frequency deviation is applied to the received signal.
  • the anti-aliasing filter 4 since the anti-aliasing filter 4 has a gradual characteristic, there is almost no influence of the difference between the spectrum of the received signal and the frequency characteristic of the anti-aliasing filter 4.
  • FIG. 4 is a diagram in which a signal component having a frequency deviation is band-limited as shown in FIG. 3, and then subjected to frequency correction, which is expressed on a frequency axis. In this case, the signal component does not change at all as compared to the case where there is no frequency deviation (see Fig. 2), and the characteristic does not deteriorate.
  • the phase reverse rotation circuit 9 for correcting the frequency deviation is provided by a digital Can be realized by the adder. That is, a large increase in the circuit scale of the frequency correction, which occurs in the demodulation circuit 14 at the time of frequency correction when the conventional quadrature demodulator is used, does not occur.
  • FIG. 5 is a diagram in which a signal component and quantization noise are simultaneously expressed on a frequency axis in a case where quantization is performed by an oversampler quantization circuit 6 (third feature).
  • an oversampler quantization circuit 6 third feature.
  • the quantization noise power integrated over the entire sampling frequency in the oversample quantization circuit 6 does not change, but the quantization noise power normalized by frequency decreases. ing.
  • the quantization noise in the portion where the signal component does not exist in FIG. 5 is removed by the digital filter 13 (fourth feature), the amount of quantization noise existing in the signal can be suppressed. .
  • a steep characteristic is not required for the band-limiting filter, and the function of the conventional band-limiting filter 100 can be easily replaced with the anti-aliasing filter 4 using an analog filter having a gentle characteristic.
  • the circuit can be simplified.
  • the present embodiment by relaxing the characteristics of the anti-aliasing filter, when there is a frequency deviation as shown in FIG. 12, that is, when a desired signal component is removed by the filter, In the case where, and the aliasing component of the signal are mixed as interference, it is possible to avoid significant characteristic deterioration of.
  • phase reverse rotation circuit 9 for performing the phase reverse rotation can be realized by a simple adder.
  • an error when an antilogarithmic transformation is performed on an amplitude value generated due to quantization of a logarithmically transformed value that is, a quantization error is equal to one bar sample.
  • the suppression can be performed by the quantization performed at a high frequency by the quantization circuit 6 and the high-precision filtering by the digital filter 13.
  • FIG. 6 is a diagram showing a configuration of a quadrature demodulator according to a second embodiment of the present invention.
  • the same components as those in FIG. 1 (Embodiment 1) described above are denoted by the same reference numerals and description thereof will be omitted.
  • 3 is a synchronization timing information input terminal
  • 8 is a buffer circuit
  • 10 is a timing control circuit.
  • the basic operation of the quadrature demodulator configured as described above will be briefly described. Here, only operations different from those in the first embodiment will be described.
  • the logarithmic conversion value output from the oversample quantization circuit 6 and the phase detection value output from the phase detection circuit 7 are stored in the buffer circuit 8. Thereafter, the timing control circuit 10 controls the output data of the buffer circuit 8 according to external timing information.
  • FIG. 7 is a diagram showing a process of detecting a logarithmically converted value based on external timing information.
  • the operation of the level detection circuit 11 when a burst signal arrives will be considered.
  • the transient response occurs at the rise of the signal level and the head of the burst cannot be used.
  • level detection can be freely performed at a time when there is a high probability that a signal component exists. Further, the influence of noise can be suppressed by the oversample described in the first embodiment. Therefore, the detection period can be shortened, a stable signal can be reproduced over the entire burst, and the delay in signal output can be reduced.
  • Embodiment 1 the same effects as those of Embodiment 1 can be obtained, and furthermore, by inputting external timing information, the level detection period can be shortened. Can be reduced.
  • the above-described polar orthogonal coordinate conversion circuit shown in FIG. 1 includes a conversion process for realizing an inverse function of the nonlinear amplifier, that is, the logarithmic amplifier 5.
  • the polar coordinate orthogonal coordinate conversion circuit 12 in addition to the conversion processing for realizing the inverse function of the nonlinear amplifier in the conversion processing, the polar coordinate orthogonal coordinate conversion circuit 12 further performs “non-linear correction”.
  • the “non-linear correction” to be added will be described with a specific example. Note that the configuration of the present embodiment is the same as in FIGS. 1 and 2 (Embodiments 1 and 2) described above, and therefore, the same reference numerals are given and the description is omitted.
  • the signal of the rectangular coordinates output from the polar rectangular coordinate conversion circuit 12 disappears in the section where the amplitude of the received signal is small.
  • FIG. 8 is a diagram showing conversion processing characteristics in the polar coordinate orthogonal coordinate conversion circuit 12. This indicates, in addition to the inverse function of the logarithmic amplifier, a non-linear correction that “the output below a certain threshold value is a constant value”.
  • Embodiments 1 and 2 the same effects as those of Embodiments 1 and 2 can be obtained, and further, a polar coordinate orthogonal coordinate conversion circuit 12 having the above conversion characteristics can be used.
  • the loss of the extracted phase information can be prevented even when the received signal drops, that is, even in a section where the amplitude of the received signal is small.
  • nonlinear distortion also occurs in saturation of a reception filter other than the logarithmic amplifier 5 and a power amplifier. Therefore, in the above-described conversion processing of the polar coordinate orthogonal coordinate conversion circuit 12 in the present embodiment, these nonlinear distortions are corrected together. As a result, in the present embodiment, even better demodulation characteristics can be obtained.
  • FIG. 9 is a diagram showing a configuration of a quadrature demodulator according to a fourth embodiment of the present invention.
  • the same components as those in FIG. 1 and FIG. 6 (Embodiments 1 and 2) described above are denoted by the same reference numerals and description thereof is omitted.
  • reference numerals 15, 16 and 17 are delay adjusting circuits.
  • non-linear amplification means that is, a signal amplified according to a non-linear function output from a logarithmic amplifier 5 and an amplitude-limited signal generally have different delay times. And the timing of each other is shifted.
  • the timing shift is corrected by each of the delay adjustment circuits.
  • the delay adjustment circuit 15 adjusts the delay time of the amplitude-limited signal by adjusting the timing of the signal input to the phase detection circuit 7 or the phase detection timing. That is, the delay adjustment circuit 15 can make adjustments at the stage before the discrete operation, and can make minute adjustments to the quantization speed.
  • the delay adjustment circuits 16 and 17 perform processing on the signal discretized at the quantization speed, so that a wide range of delay time adjustment is possible.
  • the same effects as those of the first, second, or third embodiment can be obtained, and further, by using the above-described delay adjustment circuits, the timing shift of each process is corrected.
  • the delay time of two signals output from the logarithmic amplifier 5 can be adjusted with a simple configuration.
  • the quadrature demodulator and the quadrature demodulation method according to the present invention are useful for digital radio communication such as car telephones.
  • digital radio communication such as car telephones.
  • AGC automatic gain control

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Abstract

Un filtre anti-réflexion (4) impose une limitation de bande des caractéristiques larges d'un signal reçu, et un amplificateur logarithmique (5) produit un signal amplifié fonction d'une fonction logarithmique et du signal limité en amplitude provenant tous deux du signal à bande limitée. Un circuit (7) détecteur de phase détecte l'information de phase, puis un circuit (9) inverseur de phase procède à l'inversion de phase. Un circuit (6) de quantification de suréchantillonnage quantifie le signal amplifié à une fréquence plus élevée que celle des symboles. Un circuit (11) de détection des niveaux détecte le niveau de référence de l'amplitude. Un circuit (12) de conversion des coordonnées polaires en coordonnées orthogonales assure la correction d'amplitude selon une fonction logarithmique inverse, et convertit le signal d'amplitude corrigé en une composante orthogonale correspondant au débit de suréchantillonnage. Enfin, un filtre numérique (13) impose une limitation de bande à la composante orthogonale.
PCT/JP2000/004486 1999-08-06 2000-07-06 Demodulateur orthogonal et procede de demodulation orthogonale Ceased WO2001011844A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP2001515598A JP3522725B2 (ja) 1999-08-06 2000-07-06 直交復調器および直交復調方法
AU58485/00A AU5848500A (en) 1999-08-06 2000-07-06 Orthogonal demodulator and method for orthogonal demodulation
TW089113737A TW484286B (en) 1999-08-06 2000-07-11 Orthogonal demodulator and method for orthogonal demodulation

Applications Claiming Priority (2)

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JP22431799 1999-08-06
JP11/224317 1999-08-06

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
US7158476B2 (en) 2001-07-27 2007-01-02 Samsung Electronics Co., Ltd. OFDM receiver using polar coordinate system and method thereof
JP2007013403A (ja) * 2005-06-29 2007-01-18 Agilent Technol Inc 時間差測定方法および同期化方法および測定方法、ならびに、時間差測定装置および同期化装置および測定装置
JP2007104651A (ja) * 2005-09-08 2007-04-19 Matsushita Electric Ind Co Ltd ポーラ変調送信装置、及び無線通信装置
CN101777876B (zh) * 2010-01-21 2012-03-28 清华大学 对数放大器

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