JP4226064B1 - Radio signal demodulator - Google Patents

Abstract

An object of the present invention is to provide a radio signal demodulator that improves the fluctuation tracking of a transmission path environment.
The present invention is a radio signal demodulator that receives an amplitude of an information signal on which a known pilot signal is multiplexed as a radio signal modulated in proportion to the time change of the frequency of a carrier wave. The radio signal demodulating apparatus according to the present invention includes a frequency converting unit 2, a signal combining unit 3, a first pilot signal extracting unit 11, a second pilot signal extracting unit 13, and a first pilot orthogonal signal. The generation unit 12, the second pilot orthogonal signal generation unit 14, the first error signal generation unit 16, the first weight coefficient update unit 17 and the power calculation unit 21 and the second weight coefficient update unit 23 And a second error signal generation unit 24 and a weight coefficient control unit 25.
[Selection] Figure 7

Description

  The present invention relates to a radio signal demodulating apparatus, and in particular, a radio signal that is received as a radio signal obtained by modulating the amplitude of an information signal on which a known pilot signal is multiplexed in proportion to the time change of the frequency of a carrier wave. The present invention relates to a demodulator.

  In a mobile reception environment in which a composite wave such as a reflected wave, a diffracted wave, or a scattered wave that has arrived through various propagation paths arrives at a reception point, multipath fading in which the received power level fluctuates significantly in the radio signal demodulator. Due to this multipath fading, the quality of the received signal deteriorates in the radio signal demodulator. Therefore, a radio signal demodulator used in a mobile reception environment is an indispensable technical problem to improve the quality of received signals. In particular, it is necessary to develop a radio signal demodulator that suppresses interference due to multipath fading and improves a desired power to undesired power ratio (DUR) of a demodulated signal.

  As a technique for reducing the influence of multipath fading, a diversity technique for efficiently receiving a desired signal using a plurality of antennas has been widely put into practical use. Among the diversity techniques, switching diversity for switching antenna output according to the reception power of each antenna is most often used as a radio signal demodulator in a mobile reception environment because of its simple configuration.

  As another diversity technique, an adaptive array antenna system in which the amplitude and phase of a signal received by each antenna element is independently controlled by signal processing to control the directivity of the entire system is also being studied. . This system has a characteristic of maximizing the DUR of a desired signal while suppressing unwanted waves, but the characteristic depends on a weighting factor calculation algorithm used when synthesizing signals.

  In a mobile reception environment, it is difficult to accurately grasp information regarding the direction of arrival of received signals and the number of incoming waves. Therefore, this algorithm does not require the above-mentioned information, and the minimum square error method (MMSE: Minimum Mean Square Error). ) Is often used.

  Furthermore, in this MMSE algorithm, the DUR is maximized based on the premise that the transmission signal is a constant envelope signal such as a frequency modulation (FM) wave or a phase modulation (PM) wave. There is CMA (Constant Modulus Algorithm) as an algorithm to be realized. This CMA is an algorithm based on the rule of making the envelope constant.

  The greatest feature of this CMA is that it is a blind algorithm that does not require a replica of a desired signal. Therefore, this CMA can be applied to a radio signal demodulator with a simple configuration and has already been put into practical use. Note that the radio signal demodulator using the above-described switching diversity or CMA is described in detail in Patent Document 1 and Patent Document 2.

  An adaptive array antenna system is disclosed in Patent Document 3. This Patent Document 3 discloses an adaptive array antenna system that generates a reference signal by compensating for phase and amplitude distortion of an output signal using a pilot signal time-division multiplexed with a data signal. Can be received satisfactorily.

JP 07-336130 A JP 2005-217849 A JP 07-154129 A

  However, the conventional radio signal demodulator using switching diversity has a problem in that the reception phase is deteriorated because the phase of the signal becomes discontinuous with the switching of the antenna element. In addition, the conventional radio signal demodulator using switching diversity has a problem that even in a transmission path environment where unnecessary waves exist, the unnecessary waves are combined without being suppressed.

  In addition, in the conventional radio signal demodulating apparatus using CMA, it takes time to converge to an optimum reception state, and there is a limit to the fluctuation followability of the transmission path environment in a mobile reception environment. Furthermore, in a conventional radio signal demodulator using CMA, if there is a transmission path environment where unnecessary waves exist and the power of unnecessary waves exceeds the power of the signal to be received, the unnecessary waves are received. There was a problem.

  In addition, in a radio signal demodulator that employs the configuration of Patent Document 3, when a data signal is not a complex signal (for example, a signal obtained by demodulating a frequency modulation signal), the phase and amplitude of the output signal are distorted. There was a problem that could not be compensated simultaneously.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a radio signal demodulator that improves the fluctuation tracking of the transmission path environment.

The solution according to the present invention is a radio signal demodulator for receiving a signal modulated as a radio signal in which the amplitude of an information signal on which a known pilot signal is multiplexed is proportional to the time change of the frequency of a carrier wave. For each of the output signal obtained by the frequency converter and the frequency converter that receives the radio signal using the antenna, converts the frequency of the radio signal received by each antenna to a predetermined frequency and outputs it as an output signal Multiplying the weighting factor and outputting the sum as a combined output signal; a first pilot signal extracting unit for extracting a pilot signal multiplexed on the output signal obtained from the frequency converting unit; A second pilot signal extracting unit for extracting a pilot signal multiplexed on the combined output signal obtained from the signal combining unit, and a first pilot signal extracting unit. Obtained from a first pilot orthogonal signal generation unit that generates a signal orthogonal to the first pilot signal and outputs the signal as a first pilot orthogonal signal of a complex signal, and a second pilot signal extraction unit A second pilot orthogonal signal generation unit that generates a signal orthogonal to the second pilot signal and outputs the signal as a second pilot orthogonal signal of a complex signal; and the same frequency as the second pilot orthogonal signal and the pilot signal A first error signal generation unit that outputs, as a first error signal, an error of a synthesized output signal with respect to a known pilot signal, and a first pilot orthogonal signal and a first error signal generation unit. A first weighting factor updating unit that calculates a first weighting factor using the first error signal, a power calculation unit that calculates a combined power value of the combined output signal, A second error signal generation unit that outputs the error of the combined output signal as a second error signal using the combined power value obtained from the unit and a predetermined value, an output signal obtained from the frequency conversion unit, and a signal A second weighting factor updating unit that calculates a second weighting factor using a combined output signal obtained from the combining unit, a combined power value obtained from the power calculating unit, and a predetermined value; and a first error Based on the signal and the second error signal, the first weighting factor obtained from the first weighting factor updating unit and the second weighting factor obtained from the second weighting factor updating unit are synthesized and used in the signal synthesis unit A weighting coefficient control unit that calculates the weighting coefficient to be used.

Since the radio signal demodulating device according to the present invention calculates the weighting coefficient used in the signal combining unit by combining the first weighting coefficient and the second weighting coefficient based on the first error signal and the second error signal. In addition to improving the fluctuation tracking of the transmission path environment, there is an effect that the problem of erroneously receiving unnecessary waves can be solved.

(Embodiment 1)
FIG. 1 shows a block diagram of a radio signal demodulator according to the present embodiment. The radio signal demodulating device shown in FIG. 1 has a function of receiving the amplitude of an information signal multiplexed with a known pilot signal having a predetermined frequency as a radio signal modulated in proportion to the time change of the carrier frequency. ing.

First, in the radio signal demodulator shown in FIG. 1, radio signals received using a plurality of antennas 1 ₁ to 1 _n are input to the frequency conversion unit 2, and the frequency conversion unit 2 performs frequency conversion on the received radio signals. And output as received signals R ₁ (t) to R _n (t). In this specification, the symbol (t) means a signal value at time t.

Next, the signal synthesizer 3 multiplies the received signals R ₁ (t) to R _n (t) output from the frequency converter 2 by weighting factors, which will be described later, and then sums them to a synthesized output signal Y ( t). A specific calculation method performed by the signal synthesis unit 3 will also be described in detail later in the present embodiment.

Next, the first pilot signal extraction unit 11 uses the received signals R ₁ (t) to R _n (t) output from the frequency converting unit 2 to pilot signals P ₁ (t ) To P _n (t).

A configuration example of the first pilot signal extraction unit 11 is shown in FIG. The first pilot signal extraction unit 11 illustrated in FIG. 2 includes a first demodulation unit 31 and a first bandpass filter 32. In the first demodulator 31 reproduces the received signal _{R 1 (t) ~R n (} t) the demodulating information signals _{S 1 (t) ~S n (} t). The first band pass filter 32 extracts _first pilot signals P ₁ (t) to P _n (t) from the demodulated information signals S ₁ (t) to S _n (t).

Note that the first demodulator 31 detects, for example, the frequency of the input received signals R ₁ (t) to R _n (t) and outputs an amplitude value proportional to the amount of change with respect to the time change of the frequency. Therefore, the information signals S ₁ (t) to S _n (t) are demodulated. Further, the first demodulator 31 detects the phase of the input received signals R ₁ (t) to R _n (t) and outputs an amplitude value proportional to the amount of change of the phase with respect to time. A function of demodulating the information signals S ₁ (t) to S _n (t) may be used.

Originally, it has n first demodulator 31 having the above function, and each first demodulator 31 has one input R _i (i = 1 to n) and one output S _i (i = 1). In FIG. 1, n first demodulating units 31 are represented as one block.

The first band pass filter 32 uses signal components having specific frequencies as the first pilot signals P ₁ (t) to P _n (t) for the information signals S ₁ (t) to S _n (t). Extract. The first band-pass filter 32 may be configured using, for example, an FIR (Finite Impulse Response) filter or an IIR (Infinite Impulse Response) filter whose pass band is a predetermined frequency band including a known pilot signal frequency. good.

Originally, n first bandpass filters 32 having the above-described configuration are provided, and each first bandpass filter 32 has one input S _i (i = 1 to n) and one output P _i (i In FIG. 1, n first band pass filters 32 are represented as one block.

Next, the first orthogonal signal generation unit 12 performs first orthogonal to the first pilot signals P ₁ (t) to P _n (t) obtained from the first pilot signal extraction unit 11. Pilot orthogonal signals X ₁ (t) to X _n (t) are output. The first pilot quadrature signals X ₁ (t) to X _n (t) are complex signals, and are signals in which respective in-phase signal components and quadrature signal components are orthogonal. Note that the first orthogonal signal generation unit 12 may be realized by using, for example, a Hilbert transform filter, or may be realized by using, for example, a differentiator.

  When a Hilbert transform filter is used as the first orthogonal signal generation unit 12, the performance of the filter increases and the orthogonality increases as the number of taps of the filter increases, but there is a problem that the circuit scale increases. For this reason, when a large number of taps cannot be obtained due to circuit scale restrictions or the like, the first orthogonal signal generation unit 12 is configured using an FIR filter having a predetermined finite number of taps. Moreover, when using a differentiator as the 1st orthogonal signal generation part 12, it is good also as a structure which calculates the difference of an input signal for every predetermined time interval, for example.

Originally, the apparatus includes n first orthogonal signal generation units 12 having the above-described configuration, and each first orthogonal signal generation unit 12 includes one input P _i (i = 1 to n) and one output X _i. Although it corresponds to (i = 1 to n), in FIG. 1, n first orthogonal signal generation units 12 are expressed as one block.

  Next, the second pilot signal extraction unit 13 extracts the pilot signal L (t) multiplexed on the signal from the combined output signal Y (t) obtained from the signal combining unit 3.

  A configuration example of the second pilot signal extraction unit 13 is shown in FIG. The second pilot signal extraction unit 13 illustrated in FIG. 3 includes a second demodulation unit 33 and a second bandpass filter 34. The second demodulator 33 demodulates the combined output signal Y (t) to reproduce the information signal U (t). The second band pass filter 34 extracts the second pilot signal L (t) from the information signal U (t) obtained from the second demodulator 33.

  The second demodulator 33 detects the frequency of the input composite output signal Y (t), for example, and outputs the information signal U (t) by a method of outputting an amplitude value proportional to the amount of change with respect to time change of the frequency. It has a function to demodulate. Further, the second demodulator 33 detects the phase of the input composite output signal Y (t), for example, and outputs an information signal U (t by a method of outputting an amplitude value proportional to the amount of change of the phase with respect to time. ) May be demodulated.

  The second band pass filter 34 extracts a signal component having a specific frequency from the information signal U (t) as the second pilot signal L (t). The second band-pass filter 34 is configured using, for example, an FIR filter or an IIR filter whose pass band is a predetermined frequency band including the frequency of a known pilot signal.

  Next, the second orthogonal signal generation unit 14 generates a second pilot orthogonal signal J (t) that is orthogonal to the second pilot signal L (t) obtained from the second pilot signal extraction unit 13. ,Output. The second pilot quadrature signal J (t) is a complex signal and is a signal in which the in-phase signal component and the quadrature signal component are orthogonal. Note that the second orthogonal signal generation unit 14 may be realized by using, for example, a Hilbert transform filter, or may be realized by using, for example, a differentiator.

  In addition, when a Hilbert transform filter is used as the second orthogonal signal generation unit 14, the performance of the filter increases and the orthogonality increases as the number of taps of the filter increases, but there is a problem that the circuit scale increases. . For this reason, when a large number of taps cannot be obtained due to restrictions on the circuit scale or the like, the second orthogonal signal generation unit 14 is configured using an FIR filter having a predetermined finite number of taps. Moreover, when using a differentiator as the 2nd orthogonal signal generation part 14, it is good also as a structure which calculates the difference of an input signal for every predetermined time interval, for example.

Next, the first error signal generation unit 16 uses the output J (t) of the second orthogonal signal generation unit 14 and the signal A (t) as the reference signal 15 to generate the first error signal E ₁ ( t). Here, the reference signal 15 is a signal A (t) having the same frequency as a known pilot signal. Then, the first error signal E ₁ (t) is calculated based on Equation 1 and input to the first weight coefficient updating unit 17.

Next, the first weight coefficient updating unit 17 receives the first pilot orthogonal signals X ₁ (t) to X _n (t) and the first error signal E ₁ (t), and is expressed by Equation 2. It operates to directly minimize the evaluation function Q ₁ (t). However, the “Σ” symbol in Equation 2 means the sum of times i = 1 to t, and f is called a forgetting factor and means a constant of 0 or more and 1 or less. Note that the forgetting factor f is a value that determines how much information relating to past received signals remains, and the smaller the value is set, the smaller the residual effect.

A configuration example of the first weight coefficient updating unit 17 is shown in FIG. The first weight coefficient updating unit 17 illustrated in FIG. 4 includes a first weight coefficient holding circuit 35 and a first calculator 36. First, in the first calculator 36, based on the first pilot orthogonal signals X ₁ (t) to X _n (t) and the first error signal E ₁ (t), the first weighting factor W ₁₁ (t + Δt ) To W _1n (t + Δt). The first weight coefficient holding circuit 35 holds the first weight coefficients W ₁₁ (t + Δt) to W _1n (t + Δt) calculated by the first calculator 36. Next, the first weighting factors W ₁₁ (t + Δt) to W _1n (t + Δt) held in the first weighting factor holding circuit 35 are input again to the first computing unit 36 every predetermined time, The first weighting factors W ₁₁ (t + Δt) to W _1n (t + Δt) are updated.

Specifically, the first computing unit 36 first uses the first pilot orthogonal signals X ₁ (t + Δt) to X _n (t + Δt) and the first error signal E ₁ (t + Δt) to calculate the first weighting factor. A first weight difference value D ₁ (t) for updating is calculated based on Equation 3. Here, X (t) and r _XX (t) are values represented by Equation 4 and Equation 5, respectively, H in the mathematical expression means complex conjugate transpose, and Δt means a minute time.

Next, using the first weighting factors W ₁₁ (t) to W _1n (t) held by the first weighting factor holding circuit 35 and the first weight difference value D ₁ (t), Equation 6 The first weighting factor is updated based on However, W ₁ (t) is a weight vector expressed by Equation 7, and * means a complex conjugate. Further, the first weighting factor W ₁ (t + Δt) obtained by the first weighting factor updating unit 17 is input to the signal synthesis unit 3.

Finally, the signal synthesis unit 3 multiplies each of the input first weighting factors W ₁ (t + Δt) by the received signals R ₁ (t) to R _n (t) of the antennas ₁₁ to 1 _n. The sum of the product results is output as a combined output signal Y (t). That is, the signal synthesizer 3 performs the calculation shown in Equation 8 to obtain a synthesized output signal Y (t). However, R (t) is a received signal vector expressed by Equation 9. In the signal synthesizer 3 according to the present embodiment, signals R ₁ (t) to R _n (t) received by the respective antennas are multiplied by weighting factors, and the sum thereof is obtained as a synthesized output signal Y (t). Therefore, there is an effect that the discontinuity of the phase of the signal is eliminated.

  Here, in order to compare the performance of the conventional radio signal demodulating device and the radio signal demodulating device according to the present embodiment, a device using CMA (hereinafter referred to as CMA method) which is one of the conventional radio signal demodulating devices. A configuration example of the device will be described.

  FIG. 5 is a block diagram illustrating a configuration example of the CMA system device. In the CMA system apparatus shown in FIG. 5, the same components as those in the radio signal demodulating apparatus shown in FIG.

  The power calculation unit 21 illustrated in FIG. 5 calculates the combined power value Z (t) of the signal using the combined output signal Y (t) obtained from the signal combining unit 3, and the second weight coefficient update unit 23. Output to. The power calculation unit 21 calculates the composite power value Z (t) by performing, for example, the calculation shown in Equation 10.

Next, the second weight coefficient updating unit 23 illustrated in FIG. 5 uses the combined power value Z (t) obtained from the power calculation unit 21 and the predetermined value C (t) output from the fixed value 22. It operates so as to directly minimize the value of the evaluation function Q ₂ (t) shown in Equation 11.

Specifically, a configuration example of the second weight coefficient updating unit 23 is shown in FIG. The second weight coefficient updating unit 23 illustrated in FIG. 6 includes a second weight coefficient holding circuit 37 and a second calculator 38. First, the second calculator 38 calculates second weighting factors W ₂₁ (t + Δt) to W _2n (t + Δt) based on the combined power value Z (t) and the predetermined value C (t). The second weight coefficient holding circuit 37 holds the second weight coefficients W ₂₁ (t + Δt) to W _2n (t + Δt) calculated by the second calculator 38. Next, the second weighting factors W ₂₁ (t + Δt) to W _2n (t + Δt) held in the second weighting factor holding circuit 37 are input again to the second computing unit 38 every predetermined time, The second weighting factors W ₂₁ (t + Δt) to W _2n (t + Δt) are updated.

The second calculator 38 first receives the received signals R ₁ (t) to R _n (t), the combined output signal Y (t), the combined power value Z (t), and a predetermined value C (t). Is used to calculate the second weight difference value D ₂ (t) for updating the second weighting coefficient by the equation (12). Here, μ in Equation 12 means a step gain, and is a constant that controls the speed at which the weighting coefficient is updated.

Next, using the second weighting factors W ₂₁ (t) to W _2n (t) and the second weighting difference value D ₂ (t) held by the second weighting factor holding circuit 37, the following equation 13 is obtained. The second weighting factor is updated based on However, W ₂ (t) is a weight vector represented by Equation 14. The second weighting factor W ₂ (t) obtained by the second weighting factor updating unit 23 is output to the signal synthesis unit 3.

Finally, the second weighting factor W ₂ (t) is multiplied by the received signals R ₁ (t) to R _n (t) of the antennas 1 ₁ to 1 _n in the signal synthesizer 3, and these products are multiplied. The sum of the results is output as a composite output signal Y (t). That is, the signal synthesizer 3 performs the calculation shown in Equation 15 to obtain a synthesized output signal Y (t).

As described above, in the CMA method apparatus, as shown in the equations 11 to 13 in the process of obtaining the optimum weighting factor, the value of the second error function currently obtained (the evaluation function Q ₂ ( A method called steepest descent method is used that updates the second weighting coefficient based on t)). On the other hand, in the radio signal demodulating device according to the present embodiment, as shown in Equations 2, 3, and 6, the value of the first error function calculated in the past (the evaluation function Q ₁ shown in Equation 2). (T)) A technique of RLS (Recursive Last-Squares) algorithm that updates the first weighting coefficient based on all is used. Note that the fact that the RLS algorithm has a feature that the convergence speed is faster than that of the CMA method is described in detail in the adaptive antenna technique (Nobuyoshi Kikuma, Ohmsha, pages 40 to 47). Therefore, the radio signal demodulating device according to the present embodiment has an effect of improving the follow-up performance to the transmission path environment.

  In addition, since the radio signal demodulating apparatus according to the present embodiment includes the first and second orthogonal signal generation units 12 and 13 for generating the pilot orthogonal signal, the pilot signal can be reliably complexed, The method of receiving a signal obtained by frequency-modulating an information signal multiplexed with a signal as a radio signal has an effect that the phase and amplitude distortion of the radio signal can be compensated simultaneously.

  Further, in the radio signal demodulating device according to the present embodiment, the optimum weighting factor is updated efficiently based on MMSE using the pilot orthogonal signal obtained in the radio signal demodulating process. In addition, the problem of erroneously receiving unnecessary waves is solved, and the reception performance is improved compared to the CMA method.

(Embodiment 2)
FIG. 7 shows a block diagram of a radio signal demodulating apparatus according to the second embodiment. The radio signal demodulating device shown in FIG. 7 is different from the radio signal demodulating device shown in FIG. 1 in that a power calculating unit 21, a second weight coefficient updating unit 23, a second error signal generating unit 24, The difference is that a weighting coefficient control unit 25 is provided. The power calculator 21 calculates a combined power value Z (t) of the combined output signal Y (t). The second weight coefficient updating unit 23 receives the received signals R ₁ (t) to R _n (t), the combined output signal Y (t), the combined power value Z (t), and a predetermined value C ( Based on t), second weighting factors W ₂₁ (t) to W _2n (t) are calculated. The second error signal generator 24 generates a second error signal E ₂ (t) based on the combined power value Z (t) and a predetermined value C (t). The first weighting factor control unit 25 determines each of the received signals based on the first weighting factors W ₁₁ (t) to W _1n (t) and the second weighting factors W ₂₁ (t) to W _2n (t). The third weighting factors W ₃₁ (t) to W _3n (t) for multiplying are output.

  In the radio signal demodulating device shown in FIG. 7, the same components as those in the radio signal demodulating device shown in FIG. 1 and the CMA system device shown in FIG. Omitted. Therefore, in the following, the second error signal generation unit 24 and the first weight coefficient control unit 25 will be described in detail.

First, the second error signal generation unit 24 uses the combined power value Z (t) of the power calculation unit 21 and a predetermined value C (t) to calculate the second error signal E ₂ (t ) Is calculated. The calculated second error signal E ₂ (t) is input to the first weight coefficient control unit 25.

The first weight coefficient control unit 25 includes first weight coefficients W ₁₁ (t) to W _1n (t), a first error signal E ₁ (t), and second weight coefficients W ₂₁ (t) to W _{Using the 2n} (t) and the second error signal E ₂ (t), third weighting factors W ₃₁ (t) to W _3n (t) to be multiplied with each of the received signals are output. Specifically, a configuration example of the first weight coefficient control unit 25 is shown in FIG.

The first weight coefficient control unit 25 shown in FIG. 8 includes a converter 41, a first control signal generator 42, and a first weight synthesizer 43. First, the converter 41 converts the first error signal E ₁ (t) and the second error signal E ₂ (t) into conversion signals F ₁ (t) and F ₂ (t), Output to the control signal generator 42.

As a specific conversion method in the converter 41, for example, the envelope values of the first error signal E ₁ (t) and the second error signal E ₂ (t) are converted into the conversion signals F ₁ (t) and F _2. There is a method of outputting as (t). As another method, for example, there is a method of outputting the power values of the error signal E ₁ (t) and the second error signal E ₂ (t) as converted signals F ₁ (t) and F ₂ (t). Further, the converter 41 may have a function of calculating an average value in a specific time interval. When the converter 41 has the function, the error signal E ₁ is used as the converted signals F ₁ (t) and F ₂ (t). The time average value and variance value of the envelope value or power value of (t) and the second error signal E ₂ (t) may be output.

Next, the first control signal generator 42 calculates the output signal M ₁ (t) so as to satisfy, for example, Equation 17, and outputs the output signal M ₁ (t) to the first weight synthesizer 43. .

Note that the calculation in the first control signal generator 42 is not limited to Equation 17, and the output signal M ₁ (t) may be calculated so as to satisfy Equation 18, for example. However, the symbols Max () and Num () in FIG. 18 are functions given by Equations 19, 20, and 21, respectively.

Next, the first weight synthesizer 43 uses the first weight coefficients W ₁₁ (t) to W _1n (t) and the second weight based on the output signal M ₁ (t) of the first control signal generator 42. The weighting factors W ₂₁ (t) to W _2n (t) are controlled, and the third weighting factors W ₃₁ (t) to W _3n (t) multiplied by the received signals are output.

Specifically, when the value of the output signal M ₁ (t) is obtained by Expression 17, the first weight synthesizer 43 uses, for example, Expression 22 to calculate the third weight coefficients W ₃₁ (t) to W _3n ( t) can be calculated. The calculated third weighting factors W ₃₁ (t) to W _3n (t) are input to the signal synthesis unit 3.

Further, when the value of the output signal M ₁ (t) is obtained by Expression 18, the first weight synthesizer 43 uses, for example, Expression 23 or Expression 24 to calculate the third weight coefficients W ₃₁ (t) to W _3n. (T) may be calculated.

Finally, the third weight coefficient W ₃₁ obtained by the first weight factor controlling unit _{25 (t) ~W 3n (t} ) is the received signal of the antenna ₁ 1 to 1 _n in the signal combining unit 3 R ₁ ( t) to R _n (t) are multiplied, and the sum of these multiplication results is output as a combined output signal Y (t). That is, the signal synthesis unit 3 performs the calculations shown in Equations 25 and 26 to obtain a synthesized output signal Y (t).

Since the first weight coefficient updating unit 17 shown in FIG. 1 operates using the first pilot orthogonal signals X ₁ (t) to X _n (t) as input signals, it may be desired depending on the reception environment and the characteristics of the wireless transmission path. There is a case where the operation cannot be performed. For example, when the frequency component in which the pilot signal is multiplexed hardly appears in the demodulated signal due to the frequency selective fading environment, the first weighting factor updating unit 17 illustrated in FIG. 1 may not perform a desired operation. Conceivable.

On the other hand, in the second weighting factor updating unit 23 shown in FIG. 7 according to the present embodiment, the reception signals R ₁ (t) to R _n (t) operate as input signals, and are thus multiplexed on the reception signals. It can operate independently of the quality of the pilot signal.

Therefore, when the frequency component in which the pilot signal is multiplexed hardly appears in the demodulated signal, the value of the _first error signal E ₁ (t) is compared with the value of the second error signal E ₂ (t). It is considered to be a very large value. Therefore, in the radio signal demodulating device according to the second embodiment, the first weighting factor control unit 25 monitors the first error signal E ₁ (t) and the second error signal E ₂ (t), The first weighting factors W ₁₁ (t) to W _1n (t) or the second weighting factors W ₂₁ (t) to W _2n (t) are selected to further improve the reception performance. Specifically, when the first weight coefficient control unit 25 determines that the first error signal E ₁ (t) is not so large as compared to the second error signal E ₂ (t), the pilot signal is sufficient. The first weighting factors W ₁₁ (t) to W _1n (t) are selected assuming that the power is large. On the other hand, when the first weighting factor control unit 25 determines that the first error signal E ₁ (t) is much larger than the _second error signal E ₂ (t), the pilot signal power is sufficient. If not, the second weighting factors W ₂₁ (t) to W _2n (t) are selected.

(Embodiment 3)
FIG. 9 shows a block diagram of the radio signal demodulator according to the present embodiment.

  The radio signal demodulating device shown in FIG. 9 is different in that a second weighting factor control unit 26 is provided instead of the first weighting factor control unit 25 of the radio signal demodulating device shown in FIG. The second weighting factor control unit 26 is different from the first weighting factor control unit 25 in that the combined output signal Y (t) is input in addition to the input signal of the first weighting factor control unit 25.

  In the radio signal demodulator shown in FIG. 9, the same components as those included in the radio signal demodulator shown in FIG. Therefore, in the following, the second weight coefficient control unit 26 will be described in detail.

The second weight coefficient control unit 26 includes first weight coefficients W ₁₁ (t) to W _1n (t), a first error signal E ₁ (t), and second weight coefficients W ₂₁ (t) to W _2n (t), the second error signal E ₂ (t), and the combined output signal Y (t) are input. Then, the second weight coefficient control unit 26 calculates fourth weight coefficients W ₄₁ (t) to W _4n (t) to be multiplied with each of the received signals based on these inputs. Specifically, a configuration example of the second weight coefficient control unit 26 is shown in FIG.

  In the second weighting factor control unit 26 shown in FIG. 10, the same components as those of the first weighting factor control unit 25 shown in FIG. The second weight coefficient control unit 26 includes a converter 41 having the same function as that of the second embodiment, a combined signal analysis unit 44 that performs signal analysis using the combined output signal Y (t) as an input, and second control. A signal generator 45 and a second weight synthesizer 46 are provided.

  The synthesized signal analysis unit 44 analyzes the signal quality of the synthesized output signal Y (t). Specifically, for example, there is a method of analyzing the envelope value or power value of the combined output signal Y (t) and outputting the value of this analysis signal as K (t). For example, the difference between the envelope value of the combined output signal Y (t) and a predetermined envelope value may be output as K (t) as the analysis signal. Further, the combined signal analysis unit 44 may have a memory for analyzing changes in the signal in a predetermined time interval. In this case, the envelope value of the combined output signal Y (t) and the variance value of the power value Alternatively, the variance value of the difference between the envelope value of the combined output signal Y (t) and a predetermined envelope value may be output as K (t).

  An example of a circuit configuration in which the synthesized signal analysis unit 44 outputs the variance value of the difference between the envelope value of the synthesized output signal Y (t) and a predetermined envelope value as K (t) will be described below. However, in the following description, the variance value K (t) of the difference between the envelope value of the combined output signal Y (t) and the predetermined envelope value is simply referred to as the variance value K (t).

The first weight coefficient updating unit 17 in the second embodiment operates so as to bring the combined output signal Y (t) closer to the signal A (t) that is the reference signal 15. Therefore, the value of the error signal E ₁ (t) changes with time, and the value of the combined output signal Y (t) changes accordingly.

More specifically, for example, when the period of the pilot signal is T and the delay time of the delay wave with respect to the direct wave is shorter than the period T of the pilot signal, the first weight coefficient updating unit 17 determines the delay time of the delay wave. The weighting coefficient is updated so that a signal corresponding to 0 is obtained. Then, the first weight coefficient updating unit 17 maximizes the DUR of the combined output signal Y (t) by minimizing the _first error signal E ₁ (t). Therefore, when the first error signal E ₁ (t) decreases with time, the dispersion value K (t) decreases and the DUR of the combined output signal Y (t) increases. On the other hand, when the first error signal E ₁ (t) increases, the variance value K (t) increases and the DUR of the combined output signal Y (t) decreases.

However, when the delay time of the delayed wave with respect to the direct wave is longer than the period T of the pilot signal, the above operation may not be performed. One example will be described below. First, when the delay time of the delayed wave with respect to the direct wave is 5T / 2, the first weighting factor updating unit 17 sets the weighting factor so that the delay time of the delayed wave becomes a signal corresponding to 2T (= 4T / 2). Update. At this time, even if the first error signal E ₁ (t) tends to decrease over time, the variance K (t) decreases as described above, and the DUR of the combined output signal Y (t) increases. do not do. Therefore, when the delay time of the delayed wave with respect to the direct wave is longer than the period T of the pilot signal, the radio signal is not correctly demodulated, and the value of the dispersion value K (t) is larger than the above case.

On the other hand, since the second weight coefficient updating unit 23 operates using the received signals R ₁ (t) to R _n (t) as input signals, the second weight coefficient updating unit 23 is multiplexed with the received signals R ₁ (t) to R _n (t). Operates independently of the quality of the pilot signal. That is, for example, even when the period of the pilot signal is T and the delay time of the delay wave with respect to the direct wave is 5T / 2, the second weight coefficient updating unit 23 determines that the delay wave delay time is 0 The weighting factor is continuously updated so that Therefore, when the second error signal E ₂ (t) tends to decrease with time, the second weight coefficient updating unit 23 operates so that the DUR of the combined output signal Y (t) increases. Yes.

Thus, the second weight factor controlling unit 26 according to this embodiment, the second control signal generator 45, converted signal F ₁ obtained from the first error signal _{E 1 (t) (t)} , the The control signal M ₂ (t) is generated based on the converted signal F ₂ (t) obtained from the _two error signals E ₂ (t) and the variance K (t) of the combined signal analyzer 44. Since the second weighting factor control unit 26 according to the present embodiment detects the presence or absence of a delayed wave having a delay time longer than the period T of the pilot signal, the control signal M ₂ (t) is generated. There is an effect that further quality improvement of the combined output signal Y (t) can be realized.

More specifically, for example, when the variance value K (t) is decreasing (increasing) when the conversion signal F ₁ (t) is decreasing (increasing), the second weight coefficient control unit 26 The control signal M ₂ (t) is generated by determining that there is no delay wave having a delay time longer than the period T of the pilot signal. Then, based on the control signal M ₂ (t), the second weight synthesizer 46 determines that the signal quality of the synthesized output signal Y (t) has been improved, and the first weight coefficient W ₁₁ ( t) to W _1n (t) are selected.

On the other hand, if the variance value K (t) increases (decreases) or hardly changes when the conversion signal F ₁ (t) decreases (increases), the second weight coefficient control unit 26 It is determined that there is a delayed wave having a delay time longer than the period T, and the control signal M ₂ (t) is generated. Then, based on the control signal M ₂ (t), the second weight synthesizer 46 determines that there is no improvement in the signal quality of the combined output signal Y (t), and the second weight coefficient W ₂₁ ( t) to W _2n (t) are selected.

In the radio signal demodulating apparatus according to the present embodiment, a delay having a delay time exceeding the period T of the pilot signal is generated by generating the control signal M ₂ (t) for performing the control as described above in the synthesized signal analyzing unit 44. This has the effect of suppressing signal quality degradation due to wave reception and further improving reception performance.

  Note that the description shown in the above embodiment illustrates an applicable aspect of the present invention, and the radio signal demodulating device according to the present invention is not limited to this.

1 is a block diagram of a radio signal demodulator according to Embodiment 1 of the present invention. It is a block diagram of the 1st pilot signal extraction part which concerns on Embodiment 1 of this invention. It is a block diagram of the 2nd pilot signal extraction part which concerns on Embodiment 1 of this invention. It is a block diagram of the 1st weighting coefficient update part which concerns on Embodiment 1 of this invention. 1 is a block diagram of a radio signal demodulator as a premise of the present invention. It is a block diagram of the 2nd weighting coefficient update part of the radio signal demodulation apparatus used as the premise of this invention. It is a block diagram of the radio signal demodulation apparatus according to Embodiment 2 of the present invention. It is a block diagram of the 1st weighting coefficient control part which concerns on Embodiment 2 of this invention. It is a block diagram of the radio signal demodulation apparatus according to Embodiment 3 of the present invention. It is a block diagram of the 1st weighting coefficient control part which concerns on Embodiment 3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Antenna, 2 Frequency conversion part, 3 Signal synthetic | combination part, 11 1st pilot signal extraction part, 12 1st orthogonal signal generation part, 13 2nd pilot signal extraction part, 14 2nd orthogonal signal generation part, 15 Reference signal, 16 1st error signal generation unit, 17 1st weighting factor update unit, 21 Power calculation unit, 22 Fixed value, 23 2nd weighting factor update unit, 24 2nd error signal generation unit, 25 1st 1 weight coefficient control unit, 26 second weight coefficient control unit, 31 first demodulation unit, 32 first band pass filter, 33 second demodulation unit, 34 second band pass filter, 35 first Weight coefficient holding circuit, 36 first arithmetic unit, 37 second weight coefficient holding circuit, 38 second arithmetic unit, 41 converter, 42 first control signal generator, 43 first weight synthesizer, 44 Synthetic signal analysis unit 45 Second control signal generator, 46 Second weight synthesizer.

Claims (18)

A radio signal demodulator for receiving an amplitude of an information signal multiplexed with a known pilot signal as a radio signal modulated in proportion to a time change of a carrier frequency,
A frequency converter that receives the radio signal using a plurality of antennas, converts the frequency of the radio signal received by each of the antennas to a predetermined frequency, and outputs the signal as an output signal;
A signal synthesis unit that multiplies each of the output signals obtained by the frequency conversion unit by a weighting factor and outputs the sum as a synthesized output signal;
A first pilot signal extraction unit for extracting the pilot signal multiplexed on the output signal obtained from the frequency conversion unit;
A second pilot signal extraction unit that extracts the pilot signal multiplexed on the combined output signal obtained from the signal combining unit;
A first pilot orthogonal signal generation unit that generates a signal orthogonal to the first pilot signal obtained from the first pilot signal extraction unit, and outputs the signal as a first pilot orthogonal signal of a complex signal;
A second pilot orthogonal signal generation unit that generates a signal orthogonal to the second pilot signal obtained from the second pilot signal extraction unit, and outputs the signal as a second pilot orthogonal signal of a complex signal;
A first error signal generation unit that outputs an error of the synthesized output signal with respect to the known pilot signal as a first error signal using the second pilot orthogonal signal and a reference signal having the same frequency as the pilot signal When,
A first weighting factor updating unit that calculates a first weighting factor using the first pilot orthogonal signal and the first error signal obtained from the first error signal generation unit;
A power calculator that calculates a combined power value of the combined output signal;
A second error signal generation unit that outputs an error of the combined output signal as a second error signal using the combined power value obtained from the power calculation unit and a predetermined value;
Using the output signal obtained from the frequency converter, the synthesized output signal obtained from the signal synthesizer, the synthesized power value obtained from the power calculator, and the predetermined value, A second weight coefficient updating unit for calculating a second weight coefficient;
Based on the first error signal and the second error signal, the first weight coefficient obtained from the first weight coefficient update unit and the second weight coefficient obtained from the second weight coefficient update unit ; And a weighting factor control unit that calculates the weighting factor used by the signal synthesizing unit. The radio signal demodulator according to claim 1,
The weighting factor control unit is further configured to calculate the first weighting factor and the second weighting factor based on the combined output signal obtained from the signal combining unit in addition to the first error signal and the second error signal. A radio signal demodulator that calculates the weighting factor used in a signal synthesis unit. The radio signal demodulator according to claim 1 or 2,
The first pilot signal extraction unit demodulates the output signal obtained from the frequency conversion unit and generates the information signal, and the information demodulated by the first demodulation unit. A first signal extraction unit for extracting the pilot signal multiplexed on the output signal from a signal,
The second pilot signal extraction unit demodulates the combined output signal obtained from the signal combining unit and generates a combined information signal, and a combination of the second demodulation unit And a second signal extraction unit for extracting the pilot signal multiplexed on the synthesized output signal from the information signal thus obtained. The radio signal demodulator according to claim 1 or 2,
The first pilot orthogonal signal generation unit and the second pilot orthogonal signal generation unit output a first pilot orthogonal signal and a second pilot orthogonal signal, which are complex signals, using a Hilbert transform filter or a differentiator. A radio signal demodulating device. The radio signal demodulator according to claim 1 or 2,
The radio signal demodulator, wherein the first error signal generation unit outputs a value obtained by performing complex subtraction of the reference signal from the second pilot orthogonal signal as the first error signal. The radio signal demodulator according to claim 1 or 2,
The first weighting factor updating unit updates the weighting factor by using a first weighting factor holding circuit that holds the weighting factor, the first pilot orthogonal signal, and the first error signal. And a first computing unit that calculates a difference value and updates the value of the weighting coefficient using the difference value for the weighting coefficient held in the first weighting coefficient holding circuit. Wireless signal demodulator. The radio signal demodulator according to claim 1 or 2,
The second error signal generation unit outputs a value obtained by subtracting the predetermined value from the combined power value as the second error signal. The radio signal demodulator according to claim 1 or 2,
The second weighting factor updating unit includes a second weighting factor holding circuit that holds the second weighting factor, the output signal obtained by the frequency conversion unit, the combined output signal, the combined power value, and the A difference value for updating the second weighting factor is calculated using a predetermined value, and the difference value is used for the second weighting factor held in the second weighting factor holding circuit. A radio signal demodulating device comprising: a second computing unit that updates a value of the second weighting factor. The radio signal demodulator according to claim 1,
The weight coefficient control unit includes:
A conversion means for outputting a converted signal obtained by converting the first error signal and the second error signal into an envelope value or a power value of the signal;
A first control signal generator that generates a control signal for controlling the value of the weighting coefficient output to the signal synthesis unit from the converted signal;
Based on the control signal, wherein the first weighting factor second by a weighting factor combining to produce a value for the weight coefficient, a radio and a first weight combiner you output to the signal synthesizer Signal demodulator. The radio signal demodulator according to claim 2,
The weight coefficient control unit includes:
A conversion means for outputting a converted signal obtained by converting the first error signal and the second error signal into an envelope value or a power value of the signal;
A value obtained by analyzing the envelope value or power value of the synthesized output signal, and a synthesized signal analyzing unit that outputs the value as an analysis signal;
A second control signal generator that generates a control signal for controlling the value of the weighting coefficient output to the signal synthesis unit from the converted signal and the analysis signal;
A radio signal demodulating apparatus comprising: a second weight synthesizer that generates a value of the weight coefficient to be output to the signal synthesizer from the first weight coefficient and the second weight coefficient based on the control signal. A radio signal demodulator for receiving an amplitude of an information signal multiplexed with a known pilot signal as a radio signal modulated in proportion to a time change of a carrier frequency,
  A frequency converter that receives the radio signal using a plurality of antennas, converts the frequency of the radio signal received by each of the antennas to a predetermined frequency, and outputs the signal as an output signal;
  A signal synthesis unit that multiplies each of the output signals obtained by the frequency conversion unit by a weighting factor and outputs the sum as a synthesized output signal;
  A first pilot signal extraction unit for extracting the pilot signal multiplexed on the output signal obtained from the frequency conversion unit;
  A second pilot signal extraction unit that extracts the pilot signal multiplexed on the combined output signal obtained from the signal combining unit;
  A first pilot orthogonal signal generation unit that generates a signal orthogonal to the first pilot signal obtained from the first pilot signal extraction unit, and outputs the signal as a first pilot orthogonal signal of a complex signal;
  A second pilot orthogonal signal generation unit that generates a signal orthogonal to the second pilot signal obtained from the second pilot signal extraction unit, and outputs the signal as a second pilot orthogonal signal of a complex signal;
  A first error signal generation unit that outputs an error of the synthesized output signal with respect to the known pilot signal as a first error signal using the second pilot orthogonal signal and a reference signal having the same frequency as the pilot signal When,
  A first weighting factor updating unit that calculates a first weighting factor using the first pilot orthogonal signal and the first error signal obtained from the first error signal generation unit;
  A power calculator that calculates a combined power value of the combined output signal;
  A second error signal generation unit that outputs an error of the combined output signal as a second error signal using the combined power value obtained from the power calculation unit and a predetermined value;
  Using the output signal obtained from the frequency converter, the synthesized output signal obtained from the signal synthesizer, the synthesized power value obtained from the power calculator, and the predetermined value, A second weight coefficient updating unit for calculating a second weight coefficient;
  Based on the first weighting factor obtained from the first weighting factor updating unit and the second weighting factor obtained from the second weighting factor updating unit based on the first error signal and the second error signal. A weighting factor control unit that calculates the weighting factor used in the signal synthesis unit;
  The weighting factor control unit is further configured to calculate the first weighting factor and the second weighting factor based on the combined output signal obtained from the signal combining unit in addition to the first error signal and the second error signal. A radio signal demodulator that calculates the weighting factor used in a signal synthesis unit.   The radio signal demodulator according to claim 11,
  The first pilot signal extraction unit demodulates the output signal obtained from the frequency conversion unit and generates the information signal, and the information demodulated by the first demodulation unit. A first signal extraction unit for extracting the pilot signal multiplexed on the output signal from a signal,
  The second pilot signal extraction unit demodulates the combined output signal obtained from the signal combining unit and generates a combined information signal, and a combination of the second demodulation unit And a second signal extraction unit for extracting the pilot signal multiplexed on the synthesized output signal from the information signal thus obtained.   The radio signal demodulator according to claim 11,
  The first pilot orthogonal signal generation unit and the second pilot orthogonal signal generation unit output a first pilot orthogonal signal and a second pilot orthogonal signal, which are complex signals, using a Hilbert transform filter or a differentiator. A radio signal demodulating device.   The radio signal demodulator according to claim 11,
  The radio signal demodulator, wherein the first error signal generation unit outputs a value obtained by performing complex subtraction of the reference signal from the second pilot orthogonal signal as the first error signal.   The radio signal demodulator according to claim 11,
  The first weighting factor updating unit updates the weighting factor by using a first weighting factor holding circuit that holds the weighting factor, the first pilot orthogonal signal, and the first error signal. And a first computing unit that calculates a difference value and updates the value of the weighting coefficient using the difference value for the weighting coefficient held in the first weighting coefficient holding circuit. Wireless signal demodulator.   The radio signal demodulator according to claim 11,
  The second error signal generation unit outputs a value obtained by subtracting the predetermined value from the combined power value as the second error signal.   The radio signal demodulator according to claim 11,
  The second weighting factor updating unit includes a second weighting factor holding circuit that holds the second weighting factor, the output signal obtained by the frequency conversion unit, the combined output signal, the combined power value, and the A difference value for updating the second weighting factor is calculated using a predetermined value, and the difference value is used for the second weighting factor held in the second weighting factor holding circuit. A radio signal demodulating device comprising: a second computing unit that updates a value of the second weighting factor.   The radio signal demodulator according to claim 11,
  The weight coefficient control unit includes:
  A conversion means for outputting a converted signal obtained by converting the first error signal and the second error signal into an envelope value or a power value of the signal;
  A value obtained by analyzing the envelope value or power value of the synthesized output signal, and a synthesized signal analyzing unit that outputs the value as an analysis signal;
  A second control signal generator that generates a control signal for controlling the value of the weighting coefficient output to the signal synthesis unit from the converted signal and the analysis signal;
  A radio signal demodulator comprising: a second weight synthesizer that generates a value of the weight coefficient to be output to the signal synthesizer from the first weight coefficient and the second weight coefficient based on the control signal.

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