KR20070086622A - Dc offset compensation method and device - Google Patents

Abstract

There is provided a method for accurately compensating a DC offset component contained in a signal to be modulated, i.e. a transmission signal generated in a quadrature modulation system. A DC offset correction value determined from the transmission signal is subjected to weighting in accordance with the signal level of an input signal to the quadrature modulation system as transmission data, and then the DC offset component contained in the transmission signal is compensated based on the weighted DC offset correction value.

Description

DC offset compensation method and DC offset compensation device {DC OFFSET COMPENSATION METHOD AND DEVICE}

The present invention provides a DC offset compensation method and a DC offset compensation method for compensating a DC offset included in a transmission signal in an orthogonal modulation in which a transmission signal is obtained by modulating two carriers orthogonal to each other according to an input signal consisting of an in-phase component signal and an orthogonal component signal. An offset compensation device. In particular, the present invention relates to a DC offset compensation method and a DC offset compensation device for performing the above DC offset compensation based on a DC offset correction value obtained from a transmission signal.

An orthogonal modulation system that obtains a transmission signal by modulating two carriers orthogonal to each other in accordance with an input signal composed of an in-phase component signal and an orthogonal component signal can flexibly realize various modulation schemes and signal point arrangements. It is applied to an electronic device.

33 is a diagram illustrating a schematic configuration of an orthogonal modulation system. The input signal to the orthogonal modulation system 1, which is transmission data such as a complex baseband signal, is composed of an in-phase component signal and an orthogonal component signal, and is an orthogonal modulation system by an I channel and a Q channel corresponding to the two carriers, respectively. Is entered in 1).

This input signal is converted into an analog signal for each channel by the D / A converters 13I and 13Q provided in the I and Q channels, respectively. The two carriers are modulated by the quadrature modulator 14 by this analog signal to generate a transmission signal, and the transmission signal is supplied to an antenna (not shown) through the power amplifier 15.

In such an orthogonal modulation system, when converting a transmission signal that is a complex baseband signal by an analog quadrature modulator (QMOD), an analog element circuit of the entire system of the orthogonal modulation system, for example, a digital-to-analog converter 13I. And 13Q) (hereinafter referred to as "D / A converter") or the analog element circuit between the quadrature modulator 14, due to the difference or variation in the characteristics of the circuit which multiplies in the analog region, It may be added to the transmission signal.

This DC offset is represented as a carrier leak (unnecessary wave) to the analog transmission signal after frequency conversion, resulting in leakage to an adjacent channel, resulting in deterioration of the transmission signal quality.

Conventionally, as one of the methods for compensating this DC offset, the inverse component of the DC offset added between the D / A converters 13I and 13Q and the quadrature converter 14 is converted into the D / A converters 13I and 13Q. There is a method of compensating by offsetting the DC offset by pre-applying to the transmission signal before inputting the signal.

Then, in order to generate the offset signal of the DC offset, a part of the transmission signal subjected to orthogonal modulation is fed back, and the feedback signal is analyzed to measure and correct the DC offset (for example, Patent Document 1 below); A method of subtracting a transmission signal from a feedback signal to extract error components and then measuring and correcting the DC offset has been proposed.

34 is a diagram illustrating an example of a configuration of an orthogonal modulation system that generates a offset signal of DC offset and performs offset compensation. In this configuration example, the transmission signal is subtracted from the feedback signal, the error component is extracted, and then the DC offset is measured and corrected.

To this end, the output of the power amplifier 15 is supplied to an antenna (not shown) via the directional coupler 16 and a part of the transmission signal is fed back from the monitor terminal of the directional coupler 16. The feedback signal transmitted and fed back through the mixer 82, the analog-to-digital converter (hereinafter referred to as " A / D converter ") 83, and the quadrature demodulator 84 and the orthogonal monitored signals i and q Is generated and input to the DC offset correction value estimator 20.

The DC offset correction value estimating unit 20 calculates a DC offset correction value for compensating the DC offset based on the quadrature monitored signals i and q and the input signal with respect to the in-phase component and the quadrature component. Estimate each.

The estimated DC offset correction values are added to the in-phase component and quadrature component of the input signal before inputting to the D / A converter by the adders 12I and 12Q, respectively.

The mixer 82 is connected to an output of the oscillator 81 to its local oscillation input, and by frequency converting a transmission signal supplied through the directional coupler 16 by the local oscillation signal, the transmission signal is converted into an intermediate frequency. Convert to a signal.

The A / D converter 83 converts the intermediate frequency signal into a digital signal synchronized with a clock signal of a predetermined frequency.

The orthogonal demodulator 84 orthogonally demodulates the digital signal to generate orthogonal to-be-monitored signals i and q corresponding to I and Q channels that are orthogonal to each other.

The DC offset correction value estimating unit 20 obtains an offset included in each of these signals by smoothing each of the orthogonal monitored signals i and q on a complex plane, for example. Similarly, by smoothing each of the in-phase component and the quadrature component of the input signal on the complex plane, an offset included in each of these signals is obtained.

Then, the in-phase component of the input signal is extracted from the orthogonal monitored signal i, and the orthogonal component of the input signal is extracted from each of the input signals I and Q from the orthogonal monitored signal q, and the orthogonal modulation system 1 Only the offset added by is extracted and the inverse offset is estimated as the DC offset correction value.

Patent Document 1: Japanese Patent Application Laid-Open No. 10-79692

Patent Document 2: Japanese Patent Application Laid-Open No. 2001-237723

<Start of invention>

Problems to be Solved by the Invention

As described above, the DC offset occurs due to the difference or variation in the characteristics of the circuit which multiplies in the analog region in the whole system of the orthogonal modulation system. Therefore, it is conceivable that the offset amount varies depending on the input signal to be modulated.

However, in the conventional DC offset compensation method described above, since the DC offset correction value is generated by smoothing the feedback signal, the variation of the input signal is not reflected in the DC offset correction value, so that the DC offset cannot be compensated with high precision. There is a problem.

In view of the above problems, an object of the present invention is to accurately compensate a DC offset included in the transmission signal in the orthogonal modulation.

Means for solving the problem

The inventors of the present application, in orthogonal modulation for obtaining a transmission signal by modulating two carriers orthogonal to each other in accordance with an input signal consisting of an in-phase component signal and an orthogonal component signal, the DC offset included in the transmission signal is The inventors discovered that the signal fluctuates according to the signal level, and the present invention is conceived based on this.

Therefore, in the present invention, as described in detail later with reference to the drawings, the DC offset correction value obtained from the above-described transmission signal is weighted according to the signal level of the input signal, and the DC offset with the weighting applied thereto. Based on the correction value, the DC offset is compensated.

In addition, in the present invention, each DC offset correction value corresponding to each signal level of the input signal is maintained. The DC offset correction value held in accordance with the signal level of the input signal is read, and the DC offset is compensated based on the read DC offset correction value.

Further, in the present invention, an approximation equation for calculating each DC offset correction value corresponding to each signal level from each signal level of the input signal is determined, and based on this approximation equation, the DC offset correction is made in accordance with the signal level of the input signal. The value is calculated and the DC offset is compensated based on the calculated DC offset correction value.

In this way, by weighting or changing the DC offset correction value in accordance with the signal level of the input signal, the DC offset can be compensated with high accuracy by reflecting the influence of the variation of the input signal on the offset to the correction value. Done.

1 is a first basic configuration diagram of the present invention.

2 is a characteristic graph of DC offset versus input signal level.

3 is a second basic configuration diagram of the present invention.

4 is a third basic configuration diagram of the present invention.

5 is a schematic structural diagram of an orthogonal modulation system according to a first embodiment of the present invention;

FIG. 6 is a configuration diagram (No. 1) of the DC offset correction value estimating unit shown in FIG. 5. FIG.

FIG. 7 is a configuration diagram (No. 2) of the DC offset correction value estimating unit shown in FIG. 5. FIG.

8A is a diagram illustrating a time change of an input signal level.

8B is a diagram illustrating a time change of the DC offset correction value.

8C is a diagram showing a DC offset correction value in which weighting is performed according to the input signal level of FIG. 8A with respect to the DC offset correction value in FIG. 8B.

9 is a schematic structural diagram of an orthogonal modulation system according to a second embodiment of the present invention;

10 is a diagram illustrating an averaging process of input signal levels.

11 is a schematic structural diagram of an orthogonal modulation system according to a third embodiment of the present invention;

12 is a schematic structural diagram of an orthogonal modulation system according to a fourth embodiment of the present invention.

13 is a schematic structural diagram of an orthogonal modulation system according to a fifth embodiment of the present invention;

14 is a configuration diagram of a weighting calculator shown in FIG. 13.

FIG. 15 is a flowchart showing an operation for updating weighted amount data in the weighted amount holding unit of FIG. 14. FIG.

16 is a schematic structural diagram of an orthogonal modulation system according to a sixth embodiment of the present invention;

17 is a configuration diagram of a weighting setting unit illustrated in FIG. 16.

FIG. 18 is a flowchart showing an operation for updating weighted amount data in the weighted amount holding unit of FIG. 17; FIG.

19 is a schematic structural diagram of an orthogonal modulation system according to a seventh embodiment of the present invention;

20 is a configuration diagram of a weighting setting unit illustrated in FIG. 19.

Fig. 21 is a flowchart showing an operation for adjusting each weighting amount according to the frequency of an input signal.

22 is a schematic structural diagram of an orthogonal modulation system according to an eighth embodiment of the present invention;

FIG. 23 is a configuration diagram of a weighting setting unit illustrated in FIG. 22.

24 is a flowchart showing an operation for adjusting each weighting amount in accordance with an environmental temperature.

25 is a schematic structural diagram of an orthogonal modulation system according to a ninth embodiment of the present invention;

26 is a configuration diagram of a weighting setting unit illustrated in FIG. 25.

27 is a flowchart showing an operation for adjusting each weighting amount according to the number of carriers.

28 is a schematic structural diagram of an orthogonal modulation system according to a tenth embodiment of the present invention;

29 is a schematic structural diagram of an orthogonal modulation system according to an eleventh embodiment of the present invention;

30A is a graph showing a relationship between a DC offset amount without hysteresis characteristics and a transmission signal level.

30B is a graph showing a relationship between a DC offset amount having hysteresis characteristics and a transmission signal level.

31 is a schematic structural diagram of a portion 17 of FIG. 29.

32 is a schematic structural diagram of an orthogonal modulation system according to a twelfth embodiment of the present invention;

33 is a diagram illustrating a configuration example of an orthogonal modulation system.

FIG. 34 is a diagram showing an example of the configuration of an orthogonal modulation system for generating offset signal of DC offset and performing offset compensation; FIG.

<Description of the code>

10: orthogonal modulator

20: DC offset correction value estimator

30: signal level detector

40: weight grant amount calculation part

50: weighting calculator

60: DC offset correction value holding part

70: DC offset correction value calculation unit

<Best Mode for Carrying Out the Invention>

Hereinafter, the basic configuration of the present invention. 1 is a first basic configuration diagram of the present invention.

As shown, the DC offset compensator according to the present invention transmits a modulated signal obtained by modulating two carrier waves orthogonal to each other by the orthogonal modulator 10 according to an input signal consisting of an in-phase component signal and an orthogonal component signal. The DC offset correction value estimator 20 for estimating the DC offset correction value from the signal, the signal level detector 30 for detecting the signal level of the input signal, and the weighting amount for the DC offset correction value according to the signal level The weighting amount calculation part 40 which calculates and the weighting calculation part 50 which perform weighting according to a weighting amount with respect to a DC offset correction value are provided, and are based on the DC offset correction value weighted in this way, Compensate for the DC offset included in the transmission signal.

2 is a characteristic of the DC offset included in the modulated transmission signal relative to the input signal level to the quadrature modulation system, as determined by the inventors' experiments. As shown, the DC offset included in the orthogonal modulated transmission signal varies with the signal level of the input signal for modulating the carrier wave. The occurrence of such a phenomenon is considered to be caused by the difference in the input signal levels varying the operating environment of analog circuits including the D / A converters 13I and 13Q shown in FIGS. 33 and 34.

Therefore, according to the basic configuration shown in FIG. 1, the DC offset that changes in accordance with the signal level of the input signal is assigned by weighting the DC offset correction value for compensating the DC offset according to the signal level of the input signal. It becomes possible to compensate with high precision.

3 shows a second basic configuration diagram of the present invention. As shown, the DC offset compensator according to the present invention includes a signal level detector 30 for detecting a signal level of an input signal, and a DC offset for maintaining respective DC offset correction values corresponding to each signal level of the input signal. The correction value holding part 60 is provided and the DC offset contained in a transmission signal is compensated based on the DC offset correction value read according to the signal level of the input signal. Even with such a configuration, it is possible to change the DC offset correction value in accordance with the signal level of the input signal and to compensate the DC offset with high accuracy.

4 shows a third basic configuration diagram of the present invention. As shown, the DC offset compensation device according to the present invention calculates a DC offset correction value in accordance with the signal level detection unit 30 for detecting the signal level of the input signal and the signal level based on a predetermined approximation equation. The DC offset correction value calculation part 70 is provided, and the DC offset contained in a transmission signal is compensated based on the DC offset correction value calculated according to the signal level of the input signal. Even with such a configuration, it is possible to change the DC offset correction value in accordance with the signal level of the input signal and to compensate the DC offset with high accuracy.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 5 is a schematic structural diagram of an orthogonal modulation system according to a first embodiment of the present invention.

The orthogonal modulation system 1 receives, for example, transmission data such as a complex baseband signal as an input signal, modulates two carriers orthogonal to each other with such an input signal, and transmits the transmission signal as the modulation signal. Create

The input signal consists of an in-phase component signal and an orthogonal component signal, and is input to the orthogonal modulation system 1 by the I channel and the Q channel corresponding to the two carriers, respectively.

This input signal is converted into an analog signal for each channel by the D / A converters 13I and 13Q provided in the I and Q channels, respectively. The quadrature modulator 14 then modulates the two carriers with each analog signal to generate a transmission signal (modulated signal). This transmission signal is supplied to an antenna (not shown) via the power amplifier 15.

Between the output of the power amplifier 15 and the antenna (not shown), the directional coupler 16 is connected, and the directional coupler 16 extracts a part of the transmission signal from the monitor terminal and the mixer 82 Type in

The mixer 82 converts the transmission signal supplied through the directional coupler 16 into an intermediate frequency signal by the local oscillation signal from the oscillator 81 and inputs it to the A / D converter 83.

The A / D converter 83 converts the intermediate frequency signal into a digital signal synchronized with a clock signal (not shown) of a predetermined frequency.

The orthogonal demodulator 84 orthogonally demodulates the digital signal to generate orthogonal monitored signals i and q of basebands corresponding to I and Q channels that are orthogonal to each other.

The DC offset correction value estimating unit 20 estimates the DC offset correction value for compensating the DC offset based on this feedback signal.

In addition, for brief description of the DC offset correction value estimator 20 described below, a section from each input of the D / A converters 13I and 13Q to the power amplifier 15 is described as a "forward meter". In addition, the section from the monitor terminal of the directional coupler 16 to the input of the A / D converter 83 shall be described as a "feedback system".

6 is a schematic configuration diagram of the DC offset correction value estimating unit 20.

As shown, the DC offset correction value estimator 20 includes an integrator 21-1 for smoothing the orthogonal monitored signals i and q separately on a complex plane, and an integrator 21-1 with one input. The subtractor 22 to which the output of the subtractor 22 is connected and the output value of the subtracter 22 is input; A subtractor 24 having an output of the subtractor 22 connected to the input of the subtractor 22 and an output of the delayer 23-1 connected to the other input, and a conjugate operation unit 25 connected to the output of the subtractor 24. A multiplier 26 having an output of the conjugate computing unit 25 connected to one input, a multiplier having an output of the subtractor 22 connected to one input, and an output of the multiplier 26 connected to the other input; (27) and the multiplier 28, to which the output of the multiplier 27 is connected to one input, and the step size (μ1) is supplied to the other input, and the multiplier 28 Further included is a power delay unit 23-2, and a correction value calculating section 29 for calculating the offset correction value vector from the output of the multiplier 28 is connected to the other input of the multiplier (26).

The operation of the DC offset correction value estimating unit 20 configured as described above will be described below.

The integrator 21-1 extracts the offsets included in these orthogonal monitored signals i and q by smoothing the orthogonal monitored signals i and q on a complex plane. The subtractor 22 calculates the deviation Rx _{offset [n]} of these offsets with respect to the target value "0" in order of time series n.

The retarder 23-1 and the subtractor 24 have an increase δ _[n] (= Rx _{offset [n]} -Rx between the deviation Rx _{offset [n-1]} and Rx _{offset [n]} obtained in this manner. _{Find offset [n-1]} ) in order of time series n. Conjugate arithmetic unit 25, the increment δ _[n] increment the conjugated conjugate on the complex plane with respect to δ _[n] is obtained on the '.

On the other hand, the delay unit 23-2 holds the offset compensation vector CMP _{[n] and} gives the multiplier 26 a previously obtained offset compensation vector CMP _[n-1] . The multiplier 26 obtains the preceding offset compensation vector CMP _[n-1] and the product u _[n] of δ _[n] 'in order of time series n.

Since the external product u _[n] is mathematically equivalent to the internal product of the offset compensation vector CMP _[n-1] and the increment δ _[n] , it is simply described as "internal product u _[n] " for simplicity. It is assumed that e ^j0 is set as the initial value u _[0] .

The multipliers 27 and 28 are _offset products of the internal product represented by the following expression (1) with respect to the inner product u _[n] and the deviation Rx _{offset [n]} and the step size μ1 which is a predetermined scalar amount. Update CMP _[n] sequentially.

Correction value multiplying unit 29 is set on the basis of the offset compensation vector CMP _[n] and the offset compensation vector CMP _[n] offset compensation vector CMP _[n-1] leading to a grant by the multiplier 28 the offset correction value vector Tx _{offset [n]} and then outward _{(= Tx offset [n + 1} ]) represented by the formula (2) with respect to, and updates the offset correction value vector Tx _{offset [n].}

The DC offset correction value estimating unit 20 outputs the offset correction value vector Tx _{offset [n]} that is the DC offset correction value to the adders 12I and 12Q through the weighting operation unit 50 described later.

Adders 12I and 12Q add in-phase and quadrature components of the offset correction value vector Tx _{offset [n] to} the in-phase and quadrature components of the input signal, respectively, to the D / A converters 13I and 13Q. Guide.

Here, the offset compensation vector CMP _[n-1] means a value to which the offset correction value Tx _{offset [n-1]} applied in advance of the forward system through the correction value calculator 29 is to be updated.

Increment δ _[n] is a deviation Rx _offset generated in the feedback system by applying the offset correction value vector Tx _{offset [n]} to the forward system instead of the offset correction value vector Tx _{offset [n-1]} . _It means the change of _[n] .

That is, the dot product u _[n] of the offset compensation vector CMP _[n-1] and the increment δ _[n] corresponds to the cosine value of the sum φ of the ideal amounts of the forward system and the feedback system, and this value is the deviation of these abnormal amounts. B) it will be updated accordingly with the values adapted to the change.

Therefore, the offset correction value Tx _{offset [n]} generated as described above is updated to minimize the expected value of the product of the deviation Rx _{offset [n]} and the dot product u _[n] , as represented by Equations 1 and 2 above. do.

In addition, this offset correction value vector Tx _{offset [n]} has the advantage that it is maintained at a value which is flexible and stably adapted to the deviation or variation in the abnormal amount of the feedback system.

In the DC offset correction value estimating unit 20 illustrated in FIG. 6, "0" is provided as the target value. However, as shown in FIGS. 5 and 7, the DC offset correction value estimator 20 receives an input signal and sets a target value by an integrator 21-2 that detects a DC component included in the input signal. In that sense, it is also applicable to an apparatus for generating a modulated wave in which components of a carrier signal remain. In the embodiment described below, the DC offset correction value estimating unit 20 may use any of the configurations shown in FIGS. 6 and 7.

Returning to FIG. 5, the quadrature modulation system 1 includes a signal level detector 30 for detecting a signal level (for example, a power value or an amplitude value) of the input signal, and the offset in accordance with the detected signal level. A weighting amount calculating unit 40 for calculating a weighting amount for the correction value vector Tx _{offset [n]} (hereinafter, simply referred to as an "offset correction value"), and weighting the offset correction value by this weighting amount. A weighting calculator 50 is provided.

As described with reference to FIG. 2, since the DC offset included in the orthogonal modulated transmission signal varies depending on the signal level of the input signal for modulating the carrier wave, these signal level detection unit 30 and weighting amount calculation unit 40. ) And the weighting operation unit 50 weight the DC offset correction value according to the signal level of the input signal, thereby using the DC offset correction value closer to the DC offset included in the transmission signal than in the prior art. Offset compensation becomes possible.

8A to 8C are diagrams illustrating weighting of the DC offset correction values according to the present invention, where FIG. 8A is a diagram showing a time change of the input signal level, and FIG. 8B is a DC offset correction value estimating unit. It is a figure which shows the time change of the DC offset correction value estimated by (20), and FIG. 8C shows the DC offset correction value which weighted the DC offset correction value of FIG. 8B according to the input signal level of FIG. 8A. It is a figure which shows.

As described above, the signal level detector 30 detects a signal level corresponding to the power value or amplitude value of the input signal. When a normal modulated signal is provided as transmission data, the detected signal level changes in time as shown in Fig. 8A.

On the other hand, the DC offset correction value estimated by the DC offset correction value estimator 20 with reference to FIG. 6 and FIG. 7 includes the orthogonal monitored signals i and q by the integrator 21-1. Since it is integrated and obtained from the average of the length sections of these signals, as shown in Fig. 8B, it is a signal value with little temporal variation.

Thus, as shown in FIG. 5, the weighting amount calculation unit 40 calculates the weighting amount corresponding to the detected signal level as shown in FIG. 8A, and the weighting calculation unit 50 is obtained by the weighting amount. By weighting the DC offset correction value shown in Fig. 8B, the DC offset correction value applied to the input signal by the adders 12I and 12Q is varied according to the input signal level as shown in Fig. 8C. The weighted DC offset correction value is offset compensated as the final offset correction amount.

In the delayers 11I and 11Q shown in FIG. 5, the signal level detection unit 30 detects the signal level of the input signal, and the weighting amount calculation unit 40 calculates the weighting amount according to the signal level. In order to delay the input signal by the processing time required for each.

9 is a schematic structural diagram of an orthogonal modulation system according to a second embodiment of the present invention. While the weighting amount calculated by the weighting amount calculating unit 40 can be uniquely determined according to each signal level of the input signal, the DC offset actually included in the transmission signal is an unknown factor at that time. It is contemplated that a variation occurs for the same input signal level due to the influence of. Therefore, in the present embodiment, the weighting amount calculator 40 averages the input signal level serving as a reference for calculating the weighting amount, and gently weights the DC offset correction value.

To this end, the orthogonal modulation system 1 determines the input signal level detected by the signal level detection unit 30 between the signal level detection unit 30 and the weighting amount calculation unit 40 by a predetermined average period (period). And a signal level average calculating section 31 for averaging at &lt; RTI ID = 0.0 &gt; and &lt; / RTI &gt;

When the signal level average calculating unit 31 inputs the same signal level as shown by the curve 90 in FIG. 10 from the signal level detecting unit 30, the signal level average calculating unit 31 averages the signal level in a predetermined average period, and the average value thereof. Outputs 91 to the weighting amount calculation part 40. FIG.

11 is a schematic structural diagram of an orthogonal modulation system according to a third embodiment of the present invention. In the present embodiment, instead of performing an averaging process on the input signal level, the weighting amount calculated by the weighting amount calculating unit 40 is averaged in a predetermined average section, and the DC offset correction value is Weighting based on the average value is performed.

To this end, the orthogonal modulation system 1, between the weighting amount calculation unit 40 and the weighting operation unit 50, the weighting amount calculated by the weighting amount calculating unit 40 is a predetermined average interval ( And weighted amount average calculating section 32 for averaging in the period) and outputting the average value.

12 is a schematic structural diagram of an orthogonal modulation system according to a fourth embodiment of the present invention.

As can be seen with reference to FIG. 2 described above, the variation in the DC offset caused by the change in the signal level of the input signal occurs in both the amplitude direction and the phase direction of the DC offset.

The weighting of the DC offset correction value in the Example described in this invention may be performed with respect to either the amplitude direction of a DC offset and a phase direction, and may be performed both.

In addition, in order to rotate the phase by weighting the DC offset correction value in the phase direction, as shown in FIG. 12, the weighting amount calculation unit 40 uses the in-phase component I and the quadrature component Q. The complex weighting amount Wi and Wq which have () may be calculated, and the complex weighting amount 51 as the weighting calculation unit may complex multiply the complex weighting amount to the DC offset correction value. At this time, for example, the complex weighting amounts Wi and Wq may be given by the following equations (3) and (4).

Here, r is a weighting amount along the amplitude direction of the DC offset, φ is a weighting amount along the phase direction.

FIG. 13 is a schematic configuration diagram of an orthogonal modulation system according to a fifth embodiment of the present invention, and FIG. 14 is a configuration diagram of the weighting calculator 40 shown in FIG. In the present embodiment, the weighting amount calculation unit 40 holds the weighting amount data corresponding to each signal level of the input signal, and this signal is in accordance with the signal level output by the signal level detection unit 30. The weighting amount data maintained corresponding to the level is output.

In the present embodiment, during the signal transmission, the offset amount of the DC offset included in the transmission signal is measured, and each weighting amount held in the weighting amount calculator 40 is updated so that the offset amount is minimum. .

To this end, the weighting amount calculator 40 is provided to the weighting amount holding unit 41 and the weighting amount holding unit 41 for holding each weighting amount data corresponding to each signal level of the input signal. A weighting amount updating unit 42 for updating the weighted amount data to be held is provided, and an offset amount measuring unit 43 for measuring the offset amount of the DC offset included in the transmission signal.

The weighting amount holding unit 41 includes a first address input unit a for inputting a read address corresponding to each signal level of the input signal, and a weighting amount held at an address input to the first address input unit. A first data port (b) for reading out and outputting to the weighting operation section (50), a second address input section (c) for inputting a write address designated by the weighting amount updating section (42), and a weight It is a dual port memory or a multi-port memory which inputs the weighting amount output from the provision amount update part 42, and has at least the 2nd data port d for holding it to the address input to the 2nd address input part.

The weighting amount updating unit 42 instructs the offset amount measuring unit 43 to measure the DC offset amounts included in the orthogonal monitored signals i and q received from the orthogonal demodulator 84. A received DC offset measurement command signal is output, and the DC offset amount measured by the offset amount measurement unit 43 is received.

In addition, the weighting amount updating unit 42 supplies a DC offset correction value updating command signal for instructing the DC offset correction value estimation by the DC offset correction value estimating unit 20 to perform the DC offset correction value estimating unit ( 20).

When the offset amount measuring unit 43 receives the received DC offset measurement command signal, the offset amount measuring unit 43 measures a DC offset included in the orthogonal monitored signals i and q received from the orthogonal demodulator 84 to update the weighting amount. Output to the unit 42.

The offset amount measuring unit 43 measures the integral value of the orthogonal monitored signals i and q or the difference between the integral value and the integral value of the input signals I and Q, and the orthogonal monitored signals i and q. The DC offset amount included in the measurement is measured.

Upon receiving the DC offset correction value update command signal, the DC offset correction value estimating unit 20 estimates the DC offset correction value and outputs the newly updated DC offset correction value to the weighting operation unit 50.

FIG. 15 is a flowchart showing an operation for updating the weighted amount data held in the weighted amount holding unit 41 of FIG. 14.

In step S10, the weighting amount updating unit 42 outputs the DC offset correction value updating command signal to the DC offset correction value estimating unit 20. The DC offset correction value estimation part 20 which received this signal updates the DC offset correction value output to the latest value.

In step S11, the weighting amount updating unit 42 supplies the weighting amount data held at any one of the weighting amount holding units 41, that is, the weighting amount corresponding to any one signal level of the input signal. The update permission for the data (hereinafter, referred to as "one point weighting amount data") is performed.

In step S12, the weighting amount updating unit 42 accesses the address, and increases or decreases the weighting amount data of this one point by a predetermined minute step, and again supplies it to the weighting amount holding unit 41. Fill in and update.

In addition, the determination of the update direction (increase or decrease) of the weighting amount data by the weighting amount updating unit 42 is performed in one of either increase or decrease for the first one update, and then DC measured in the next step. The offset amount is observed and automatically set in the direction in which the offset amount decreases.

The weighted amount data of one point updated in this way is read as an address to be read when the input signal of the corresponding signal level is applied, and is applied to the offset correction weighting in the weighting calculation unit 50. do. In this case, the update of the weighted amount data causes variation in the DC offset included in the transmission signal.

In step S13, the weighting amount updating unit 42 outputs the received DC offset measurement command signal to the offset amount measuring unit 43, and obtains the latest DC offset amount from the offset amount measuring unit 43. .

In step S14, it is determined whether or not the offset amount acquired in step S13 becomes the minimum value with respect to the variation of the weighting amount data of the one point. If the offset amount becomes the minimum value, data update for this one-point weighting amount data is stopped (step S15). If the offset amount is not the minimum value, the process returns to step S12 to update the weighting amount data for this one point. Repeat.

The determination of whether or not the offset amount measured in step S13 becomes the minimum value is, for example, comparing the offset amount measured in step S13 of the previous loop with the offset amount measured in the current loop, and continuing until the last comparison. It may be performed by determining whether or not the offset amount that has decreased is increased to a minimum value.

In step S16 and step S17, steps S11 to S15 are repeated for all the weighting amount data held in the weighting amount holding unit 41. This updates each weighting data corresponding to each signal level of the input signal.

FIG. 16 is a schematic structural diagram of an orthogonal modulation system according to a sixth embodiment of the present invention, and FIG. 17 is a structural diagram of the weighting calculator 40 shown in FIG. In the present embodiment, similarly to the fifth embodiment, the weighting amount calculation unit 40 holds the weighting amount data corresponding to each signal level of the input signal, and the signal level detecting unit 30 Although it is common in the point which outputs the weighted amount data hold | maintained corresponding to this signal level according to the signal level to output, this weighted amount data is used, using a training signal before the signal transmission of the orthogonal modulation system 1, Different in terms of setting in advance.

To this end, the weighting amount calculation unit 40 includes a weighting amount setting unit 44 for setting the weighting amount holding unit 41 and the weighting amount data held in the weighting amount holding unit 41. ) And the offset amount measuring section 43 is provided.

The weighting amount setting unit 44 receives a command for instructing the offset amount measuring unit 43 to measure the DC offset amount included in the orthogonal monitored signals i and q received from the orthogonal demodulator 84. A DC offset measurement command signal is output, and the DC offset amount measured by the offset amount measurement unit 43 is received.

In addition, the weighting amount setting unit 44 is normal transmission data which is a modulation signal whose signal level is changed with respect to a transmission side apparatus (not shown) which inputs an input signal (transmission data) to the orthogonal modulation system 1. Instead, it outputs an unmodulated setting signal for inputting a training signal which is an unmodulated signal with a constant signal level.

FIG. 18 is a flowchart showing an operation for updating the weighted amount data held in the weighted amount holding unit 41 of FIG. 17.

In step S20, the orthogonal modulation system 1 inputs normal transmission data generated by the transmission side apparatus (not shown).

In step S21, the weighting amount setting unit 44 outputs the received DC offset measurement command signal to the offset amount measuring unit 43, and acquires the DC offset amount X included in the modulated signal.

Next, in step S22, the weighting amount setting part 44 outputs the said unmodulated setting signal to a transmission side apparatus (not shown). As a result, the transmitting side apparatus (not shown) inputs the training signal, which is an unmodulated signal of a constant signal level, into the quadrature modulation system 1, instead of the normal transmission data which is a modulation signal.

In step S23, the weighting amount setting unit 44 outputs the received DC offset measurement command signal to the offset amount measuring unit 43, and acquires the DC offset amount Y when the training signal is input.

In step S24, the weighting amount setting unit 44 calculates a difference between the DC offset amount Y measured in step S23 and the DC offset amount X measured in step S21, and applies the signal level of the training signal. As the corresponding weighting data, the difference is stored in the weighting amount holding unit 41.

In steps S25 and S26, steps S23 to S24 are repeated for all signal levels while changing the signal level of the training signal, and the weighting amount holding unit 41 stores weighting data corresponding to each signal level.

FIG. 19 is a schematic configuration diagram of an orthogonal modulation system according to a seventh embodiment of the present invention, and FIG. 20 is a configuration diagram of the weighting calculator 40 shown in FIG. In this embodiment, the weighting amount calculator 40 adjusts each weighting amount of the DC offset correction value according to the frequency of the input signal.

To this end, as shown in FIG. 20, the weighting calculator 40 assigns a plurality of weights to hold weighting amount data corresponding to each signal level of the input signal for each of a plurality of frequencies of the input signal. The amount holding part 41 is provided. Each weighting amount holding part 41 is comprised by the holding means, such as several memory which hold | maintains weighting amount data corresponding to each frequency of an input signal, respectively.

The weighting calculator 40 receives frequency information indicating the frequency of the input signal from a transmission side apparatus (not shown) that inputs transmission data to the orthogonal modulation system 1, and corresponds to the frequency information. The switching control unit 45 for switching to select the memory constituting the weighting amount holding unit 41 to be described and the address input unit of the memory of the weighting amount holding unit 41 selected by the switching control unit 45 are read out. An address switching unit 46 for switching and connecting the level signal of the signal level detection unit 30 as an address, and a data switching unit 47 for switching the data output unit of the selected memory to connect to the weighting operation unit 50; Equipped.

21 is a flowchart showing an operation for adjusting each weighting amount in accordance with the frequency of an input signal.

In step S30, the switching control part 45 of the weighting calculation part 40 of FIG. 20 receives the frequency information which shows the frequency of an input signal from the said transmission side apparatus (not shown). When there is a change in frequency, in step S31, the switching control unit 45 in Fig. 20 selects the memory constituting the weighting amount holding unit 41 corresponding to the received frequency information, and this is the address switching unit. (46) and the data switching unit 47 connect to the level signal output unit of the signal level detection unit 30 in FIG. 19 and the input unit of the weighting operation unit 50, respectively.

22 is a schematic structural diagram of an orthogonal modulation system according to an eighth embodiment of the present invention, and FIG. 23 is a structural diagram of the weighting calculation unit 40 shown in FIG. 22. In the present embodiment, the weighting amount calculation unit 40 adjusts each weighting amount of the DC offset correction value according to the environmental temperature at which orthogonal modulation is performed by the orthogonal modulation system 1.

To this end, as shown in FIG. 23, the weighting calculator 40 maintains weighting amount data corresponding to each signal level of the input signal for each of a plurality of environment temperatures at which orthogonal modulation is performed. A plurality of weighting amount holding units 41 are provided. Each weighting amount holding part 41 is comprised by the holding means, such as several memory which hold | maintains weighting amount data corresponding to each environmental temperature, respectively.

Then, the weighting calculator 40 receives the environmental temperature information from the orthogonal modulation system 1 with an external temperature sensor (not shown), and supplies the weighting amount holding unit 41 corresponding to the environmental temperature. The level of the signal level detection unit 30, which is a read address, is provided in the switching control unit 45 for switching to select the memory to be formed, and the address input unit of the memory of the weighting amount holding unit 41 selected by the switching control unit 45. An address switching unit 46 for switching signals and connecting them, and a weighting operation unit 50, are provided with a data switching unit 47 for switching and connecting the data output unit of the selected memory.

24 is a flowchart showing an operation for adjusting each weighting amount according to the environmental temperature.

In step S30, the switching control part 45 of the weighting calculation part 40 of FIG. 23 receives environmental temperature information which shows environmental temperature from the said temperature sensor (not shown). And if there is a change in environmental temperature, in step S31, the switching control part 45 of FIG. 23 selects the said memory which comprises the weighting amount holding part 41 corresponding to the received environmental temperature information, and this is an address. Via the switching section 46 and the data switching section 47, the level signal output section of the signal level detecting section 30 in FIG. 22 and the input section of the weighting calculation section 50 are connected respectively.

25 is a schematic configuration diagram of an orthogonal modulation system according to a ninth embodiment of the present invention, and FIG. 26 is a configuration diagram of the weighting calculation unit 40 shown in FIG. 15. In this embodiment, the weighting amount calculator 40 adjusts each weighting amount of the DC offset correction value according to the number of carriers constituting the input signal.

To this end, as shown in FIG. 26, the weighting calculator 40 is configured to hold a plurality of weighting amount holding units for holding weighting amount data corresponding to the signal level of the input signal with respect to the number of carriers of the input signal. (41) is provided. Each weighting amount holding unit 41 holds weighting amount data corresponding to the number of carriers of the input signal, respectively.

The weighting calculation unit 40 receives carrier number information indicating the number of carriers of the input signal from a transmission side apparatus (not shown) that inputs transmission data to the orthogonal modulation system 1, and the number of carriers. A switching control section 45 for switching to select a memory constituting the weighting amount holding section 41 corresponding to the information, and an address input section of the memory constituting the weighting amount holding section 41 selected by the switching control section 45; A data section for switching the data output section of the selected memory to the address switching section 46 for switching the level signal of the signal level detection section 30 which is a read address, and the weighting operation section 50 for connection. The affected part 47 is provided.

27 is a flowchart showing an operation for adjusting each weighting amount in accordance with the number of carriers of an input signal.

In step S50, the switching control part 45 of the weighting calculation part 40 of FIG. 26 receives the carrier number information which shows the number of carriers of an input signal from the said transmission side apparatus (not shown). When there is a change in the number of carriers, in step S51, the switching control unit 45 selects the weighting amount holding unit 41 corresponding to the received frequency information, and the address switching unit 46 and the data switching unit. Reference is made to 47 to connect the level signal of the signal level detection unit 30 and the input of the weighting operation unit 50.

28 is a schematic structural diagram of an orthogonal modulation system according to a tenth embodiment of the present invention. According to the present embodiment, in the case of an orthogonal modulation system in which the relationship between the signal level of the input signal and the DC offset amount is almost proportional, it is possible to compensate the DC offset amount with a simple configuration.

To this end, the orthogonal modulation system 1 is a weighting amount calculation unit that multiplies a signal level detected by the signal level detection unit 30 by a constant 1 / α to calculate a weighting amount proportional to this signal level. The multiplier 46 and the multipliers 52I and 52Q multiply the weighting amount by the DC offset correction value for the DC offset correction value estimating unit 20 to output the weighting amount.

29 is a schematic structural diagram of an orthogonal modulation system according to an eleventh embodiment of the present invention. In this embodiment, each DC offset correction value corresponding to the signal level of the input signal is maintained. The DC offset correction value held in accordance with the signal level of the input signal is read out, and the DC offset is compensated based on the read DC offset correction value.

To this end, the quadrature modulation system 1 has a DC offset correction value holding unit 60 for holding each DC offset correction value corresponding to each signal level of the input signal. The DC offset correction value holding unit 60 may be configured by a look up table (LUT) or the like. The DC offset correction value holding unit 60 uses the input signal level detected by the signal level detecting unit 30 as a read address, reads each DC offset correction value corresponding to this signal level, and adds 12I and 12Q. )

The DC offset correction value held by the DC offset correction value holding unit 60 may use a DC offset correction value estimated by the DC offset correction value estimating unit 20 from the transmission signal.

In addition, when there is a variation in the DC offset included in each of the transmission signals by the input signal having the same signal level, the DC offset correction value held in the DC offset correction value holding unit 60 is converted into a DC offset correction value estimating unit ( Each time the DC offset correction value is outputted from 20), the DC offset correction value is maintained so as to gradually approach the DC offset correction value output from the DC offset correction value estimator 20, instead of updating the output value itself. You may update.

To this end, the orthogonal modulation system 1 calculates the DC offset correction value held by the DC offset correction value holding unit 60 as shown in FIG. 29 by the DC offset correction value estimating unit 20. And a DC offset correction value updating unit 61 for updating to gradually approach a DC offset correction value of.

The DC offset correction value updating unit 61 holds the updated value Txm _{[n + 1]} of the DC offset correction value held in the DC offset correction value holding unit 60 to hold the DC offset correction value currently held. Based on the value Txm _[n] and the DC offset correction value Tx _{offset [n]} output from the DC offset correction value estimating unit 20, for example, the following equation (5).

May be calculated and held in the DC offset correction value holding unit 60 while gradually updating the DC offset correction value. Here, mu 2 is a constant that determines a predetermined change step amount.

Consider the case where the hysteresis described in Figs. 30A and 30B exists in the DC offset included in the transmission signal. 30A is a graph showing the relationship between the DC offset amount without hysteresis characteristics and the transmission signal level, and FIG. 30B is a graph showing the relationship between the DC offset amount with hysteresis characteristics and the transmission signal level. If there is such a hysteresis, as shown in Fig. 30B, in the case where the transmission signal level increases and decreases, even if the transmission signal is the same signal level, a difference occurs in the offset amount of the DC offset included therein.

Therefore, in order to compensate for such an offset amount, the DC offset correction value holding unit 60 shown in FIG. 29 is multidimensional, and even if the input signal is the same, depending on the amount of change in the time series of the signal level of the input signal, It is necessary to prepare a plurality of offset correction values.

FIG. 31 shows a configuration example in the case where the DC offset correction value holding unit 60 of the orthogonal modulation system of FIG. 29 is multidimensionalized to compensate for the DC offset amount having hysteresis characteristics. It is a figure which shows about 17).

In this configuration, a delay 62 for delaying the input signal from the output of the signal level detector 30, one input is connected to the output of the delay 62, and the other output is a signal level detector ( And a signal level change calculating section 67 made up of a subtractor 63 directly connected to the output of 30). The signal level change calculating section 67 calculates the amount of change in the time series of the signal level of the input signal by obtaining the difference between the current input signal level and the preceding input signal level.

Here, using the DC offset correction value holding unit 60 as an example, the two-dimensionalization and output of the signal level detection unit 30 are read addresses of the first dimension, and the output of the subtractor 63 is read in the second dimension. It consists of a two-dimensional lookup table which is used as a bet address.

With this configuration, the DC offset correction value holding unit 60 responds to the amount of change in the time series of each signal level of the input signal and the signal level of the input signal when the DC offset amount has hysteresis characteristics. The DC offset correction value can be held, and the held DC offset correction value can be read out in accordance with each signal level of the input signal and the amount of change calculated by the signal level change calculation unit.

In this configuration, the output of the signal level detector 30 is used as the write address of the first dimension, and the output of the subtractor 63 is used as the write address of the second dimension, and in the time sequence of the input signal level and the signal level. When the input signal having the input signal level and the change amount in the chronological order is input to the DC offset correction value estimating section 20, respectively, to the write addresses of the first and second dimensions, respectively corresponding to the change amounts of? The DC offset correction value output by (20) may be written.

With such a configuration, the DC offset correction value estimating unit when the input signal having the signal level corresponding to the address of the first dimension and the change amount in the time series corresponding to the address of the second dimension is orthogonally modulated. It is possible to hold the DC offset correction value output from 20 at the addresses of the first and second dimensions of the DC offset correction value holding unit 60. In addition, the delay units 64 and 65 are provided for the first and second dimensions by the processing time from when the input signal is orthogonally modulated until the DC offset correction value is output from the DC offset correction value estimator 20. Is a delay for delaying each of the address signals.

32 is a schematic structural diagram of an orthogonal modulation system according to a twelfth embodiment of the present invention. In this embodiment, an approximation formula for calculating each DC offset correction value corresponding to each signal level is determined from each signal level of the input signal, and based on this approximation formula, the DC offset is made in accordance with the signal level of the input signal. The correction value is calculated and the DC offset is compensated based on the calculated DC offset correction value.

To this end, the orthogonal modulation system 1 includes a DC offset correction value calculator 70 for calculating a DC offset correction value according to each signal level of the input signal based on a predetermined approximation equation, and the predetermined approximation equation. A parameter calculator for calculating a parameter defining the approximation equation from a parameter holding unit 71 for holding a parameter for defining the equation and a DC offset correction value output from the DC offset correction value estimating unit 20 ( 73).

For example, the approximation formula may be a polynomial whose signal level of the input signal is a variable, and the parameter may be a coefficient multiplied by each term included in the polynomial. At this time, the DC offset correction value calculation unit 70 calculates the DC offset correction value according to each signal level of the input signal based on this polynomial.

In addition, the parameter calculation unit 73 performs each DC offset correction estimated by the DC offset correction value estimating unit 20 from the transmission signal when the signal levels of the plurality of input signals and the input signals of these signal levels are orthogonally modulated. Based on a value, you may calculate the said parameter by the least square method, for example.

In addition, the DC offset compensation method and the DC offset compensation device according to the present invention can be suitably used to compensate for the DC offset included in the transmission signal generated in the analog orthogonal modulation system used for high speed wireless communication such as IMT2000. The present invention is not limited to this, and can be widely used in an orthogonal modulation system in which a transmission signal is obtained by modulating two carrier waves orthogonal to each other in accordance with an input signal consisting of an in-phase component signal and an orthogonal component signal.

Claims (39)

DC offset to compensate for the DC offset component included in the transmission signal obtained by modulating two carriers orthogonal to each other in accordance with an input signal consisting of an in-phase component signal and a quadrature component signal, based on the DC offset correction value obtained from the transmission signal. As a compensation method, The DC offset compensation method is characterized in that the weighting is performed according to the signal level of the input signal. The method of claim 1, The DC offset correction value is weighted according to an average value within a predetermined period of the signal level of the input signal. The method of claim 1, The DC offset compensation method is characterized in that the weighting is performed according to an average value obtained by averaging each weighting amount corresponding to each signal level of the input signal within a predetermined period. The method of claim 1, And weighting the DC offset correction value with respect to an amplitude component and / or a phase component of the DC offset component. The method of claim 1, Maintaining each weighting amount of the DC offset correction value, And the weighting calculator is configured to weight the DC offset correction value according to the held weighting amount. The method of claim 5, Measure an offset amount of the DC offset component included in the transmission signal, And updating each of the weighted amounts to be maintained so that the offset amount is minimized. The method of claim 1, For each signal level of the input signal, each weighting amount of the DC offset correction value is set in advance and maintained, And DC weighting the DC offset correction value in accordance with the set weighting amount. The method of claim 7, wherein An offset amount of a DC offset component included in the transmission signal modulated using any transmission data as the input signal, Measuring the respective offset amounts of the DC offset components included in the transmission signal modulated using the training signal of the signal level corresponding to each signal level as the input signal, Each weighting amount of the DC offset correction value for the input signal of each signal level is respectively based on the difference between the offset amount for the arbitrary transmission data and each offset amount for the training signal of each signal level. DC offset compensation method characterized in that the calculation. The method of claim 1, And adjusting each weighting amount of the DC offset correction value according to the frequency of the input signal. The method of claim 1, A DC offset compensation method, wherein each weighting amount of the DC offset correction value is adjusted according to an environment temperature at which the orthogonal modulation is performed. The method of claim 1, DC weighting compensation method, characterized in that each weighting amount of the DC offset correction value is adjusted according to the number of carriers constituting the input signal. The method of claim 1, DC offset compensation method, characterized in that the weighting in proportion to the signal level of the input signal to the DC offset correction value. In orthogonal modulation in which a transmission signal is obtained by orthogonally modulating two orthogonal carriers in accordance with an input signal composed of an in-phase component signal and an orthogonal component signal, the transmission signal is included in the transmission signal based on a DC offset correction value obtained from the transmission signal. A DC offset compensation method for compensating a DC offset component, Maintain the DC offset correction value corresponding to each signal level of the input signal, According to the signal level, the held DC offset correction value is read out, And the DC offset component is compensated based on the read DC offset correction value. The method of claim 13, And maintaining the DC offset correction value in a correction value holding table accessed by addressing the signal level of the input signal. The method of claim 13, Estimate each DC offset correction value from the transmission signal corresponding to the input signal of each signal level, respectively, And based on each of the DC offset correction values, updating each of the DC offset correction values held corresponding to each of the signal levels. The method of claim 13, Each DC offset correction value is maintained corresponding to each signal level of the input signal and the amount of change in the chronological order of the signal level of the input signal, The retained DC offset correction value is read in accordance with the amount of change in the time series of each signal level of the input signal and the signal level of the input signal, And the DC offset component is compensated based on the read DC offset correction value. The method of claim 16, Estimating each said DC offset correction value from each said signal level and the said transmission signal corresponding to each input signal which has each said variation amount, respectively, The estimated DC offset correction value is maintained corresponding to each of the signal level and each change amount. The method of claim 16, Estimating each DC offset correction value from each of said signal level and said transmission signal corresponding to each input signal having said variation amount, respectively, And based on the estimated respective DC offset correction values, updating each DC offset correction value held corresponding to each of the signal level and each change amount. In a quadrature modulation in which a transmission signal is obtained by modulating two carriers orthogonal to each other in accordance with an input signal consisting of an in-phase component signal and a quadrature component signal, the DC offset component included in the transmission signal is converted into a DC offset correction value obtained from the transmission signal. Based on the DC offset compensation method, An approximation equation for calculating the respective DC offset correction values corresponding to the respective signal levels is determined from the respective signal levels of the input signal, Based on the approximation formula, the DC offset correction value is calculated according to the signal level of the input signal, And the DC offset component is compensated based on the calculated DC offset correction value. The method of claim 19, Estimating each DC offset correction value corresponding to each signal level, respectively, from the transmission signal corresponding to the input signal of each signal level, From the respective DC offset correction values estimated corresponding to the respective signal levels, a parameter defining the approximation equation is obtained. And the DC offset correction value for compensating the DC offset component according to the signal level of the input signal based on the approximation equation and the parameter. DC offset correction value obtained from the transmission signal by calculating the DC offset component included in the transmission signal in orthogonal modulation in which a transmission signal is obtained by modulating two orthogonal carriers in accordance with an input signal composed of an in-phase component signal and an orthogonal component signal. A DC offset compensation device that compensates based on A DC offset correction value estimator for estimating the DC offset correction value from the transmission signal; A signal level detector for detecting a signal level of the input signal; A weighting amount calculator for calculating a weighting amount for the DC offset correction value according to the detected signal level; A weighting calculator for weighting the DC offset correction value according to the weighting amount. DC offset compensation device characterized in that it comprises a. The method of claim 21, A signal level average calculating unit configured to calculate an average value within a predetermined period of the signal level of the input signal, And the weighting amount calculating unit calculates the weighting amount according to the average value. The method of claim 21, A weighted amount average calculating unit configured to calculate an average value obtained by averaging the weighted amount within a predetermined period; And the weighting operation unit weights the DC offset correction value according to the average value. The method of claim 21, And the weighting amount is a weighting amount of the DC offset correction value with respect to an amplitude component and / or a phase component of the DC offset component. The method of claim 21, And a weighting amount holding unit for holding each weighting amount of the DC offset correction value, And the weighting calculator is configured to weight the DC offset correction value according to the held weighting amount. The method of claim 25, An offset amount measuring unit for measuring an offset amount of a DC offset component included in the transmission signal from the transmission signal; And a weighting amount updating unit for updating each weighted amount of the held DC offset correction value and minimizing the measured offset amount. The method of claim 25, A weighting amount setting unit for setting each weighting amount of the DC offset correction value for each signal level of the input signal, And the weighting amount holding unit maintains each weighting amount set in advance by the weighting amount setting unit. The method of claim 27, An offset amount measuring unit for measuring an offset amount of a DC offset component included in the transmission signal from the transmission signal, The weighting amount calculation unit is configured to output an offset amount of a DC offset component measured with respect to the transmission signal modulated using any transmission data as the input signal, and a training signal having a signal level corresponding to each signal level. And the respective weighting amounts are respectively calculated based on the difference of the offset amounts measured with respect to the modulated transmission signal. The method of claim 21, The weighting amount calculating unit adjusts each weighting amount of the DC offset correction value according to the frequency of the input signal. The method of claim 21, The weighting amount calculation unit adjusts each weighting amount of the DC offset correction value according to an environment temperature at which the orthogonal modulation is performed. The method of claim 21, The weighting amount calculation unit adjusts each weighting amount of the DC offset correction value according to the number of carriers constituting the input signal. The method of claim 21, And the weighting amount calculating unit calculates a weighting amount proportional to a signal level of the input signal. DC offset correction value obtained from the transmission signal by calculating the DC offset component included in the transmission signal in orthogonal modulation in which a transmission signal is obtained by modulating two orthogonal carriers in accordance with an input signal composed of an in-phase component signal and an orthogonal component signal. A DC offset compensation device that compensates based on A signal level detector for detecting a signal level of the input signal; A DC offset correction value holding unit for holding each DC offset correction value corresponding to each signal level of the input signal, And the DC offset correction value read in accordance with the detected signal level, and compensating for the DC offset component based on the DC offset correction value. The method of claim 33, wherein A DC offset correction value estimator which estimates the DC offset correction value from the transmission signal; A DC offset correction value updating unit updating the DC offset correction value held in the DC offset correction value holding unit based on the estimated DC offset correction value. DC offset compensation device characterized in that it comprises a. The method of claim 33, wherein A signal level change calculating section for calculating an amount of change in the chronological order of the signal level of the input signal, The DC offset correction value holding unit maintains the DC offset correction value corresponding to each signal level of the input signal and the amount of change in the time series of the signal level of the input signal The retained DC offset correction value is read in accordance with each signal level of the input signal and the change amount calculated by the signal level change calculation unit, and based on the read DC offset correction value, the DC offset DC offset compensation device, characterized in that to compensate the components. 36. The method of claim 35 wherein A DC offset correction value estimating unit for estimating the DC offset correction value from the transmission signal, The DC offset correction value holding unit estimates the DC offset correction value estimated by the DC offset correction value estimating unit from each of the signal level and the transmission signal corresponding to each input signal having the change amount. The DC offset compensation device, characterized in that for holding corresponding to each signal level and each change amount. 36. The method of claim 35 wherein A DC offset correction value estimator which estimates the DC offset correction value from the transmission signal; A DC offset correction value updating unit updating the DC offset correction value held in the DC offset correction value holding unit based on the estimated DC offset correction value. DC offset compensation device characterized in that it comprises a. DC offset correction value obtained from the transmission signal by calculating the DC offset component included in the transmission signal in orthogonal modulation in which a transmission signal is obtained by modulating two orthogonal carriers in accordance with an input signal composed of an in-phase component signal and an orthogonal component signal. A DC offset compensation device that compensates based on A signal level detector for detecting a signal level of the input signal; A DC offset correction value calculating section for calculating the DC offset correction value according to a signal level of the input signal based on a predetermined approximation equation, And the DC offset component is compensated based on the calculated DC offset correction value. The method of claim 38, A DC offset correction value estimator which estimates the DC offset correction value from the transmission signal; A parameter calculating unit for calculating a parameter defining the approximation equation from each of the DC offset correction values estimated from the transmission signal corresponding to the input signal of the respective signal levels; A parameter holding unit for holding the calculated parameter, And the DC offset correction value calculating unit calculates the DC offset correction value for compensating the DC offset component based on the predetermined approximation equation and the parameter.

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