JP3145015B2 - Transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission apparatus used for wireless communication, and more particularly to a time division multiple access communication (TD).
MA) a burst wave transmitter used in a system.

[0002]

2. Description of the Related Art As mobile communication means such as portable telephones generally penetrate, the shortage of radio wave resources has become remarkable, and effective use of frequencies by digitally modulated waves has been attempted. That is, at present, the π / 4 shift differential QPSK modulation is used in the mobile phone system, but this modulation method modulates information only in phase, so that the transmission efficiency is poor.

In order to solve this problem, 16QAM which modulates not only the phase but also the amplitude simultaneously, and M16QAM which is a modification of 16QAM, have been applied to mobile communication. For example, M16QAM is adopted in a digital MCA system, and achieves high transmission efficiency.

However, in a method of modulating not only the frequency but also the amplitude, such as M16QAM, distortion due to the influence of the non-linearity of the amplifier is apt to occur, resulting in interference with adjacent channels and an increase in transmission error rate. Therefore, it is necessary to compensate for the non-linearity. However, a transmitter having a function of compensating for the non-linearity of the amplifier including the one caused by an environmental change has already been proposed (Japanese Patent Application Laid-Open No. 61-214843).
Gazette).

FIG. 2 is a functional diagram of the transmitting apparatus according to the above proposal, in which distortion characteristics of the amplifier 24 using the output amplitude of the signal generation unit 21 as an index are written in advance in the distortion storage unit 29. The amplitude value of the baseband complex signal generated by the signal generation unit 21 is calculated by the amplitude calculation unit 28. The distortion value corresponding to the amplitude value is read from the distortion storage unit 29 using the calculated amplitude value as an index.

The signal generated by the signal generating means 21 is subjected to predistortion by the predistortion means 12 in order to compensate for the read distortion value. The signal to which the predistortion has been given is quadrature-modulated by the quadrature modulation means 13, and
It is output after being amplified by. Although the output signal is distortion-compensated, the change in distortion due to environmental changes such as the temperature of the amplifier 24 and the applied voltage cannot be fully compensated and remains as an error.

In order to further reduce the residual error, the transmission output is fed back and returned to the baseband signal by the quadrature demodulation means 25, and then the error with respect to the signal generated by the signal generation means 21 is calculated by the error calculation means 26. I do. Then, the distortion signal at that time is calculated by the correction signal generation unit 27 based on the error and the distortion value of the distortion storage unit 29, and the distortion value of the distortion storage unit 29 is rewritten, thereby sequentially improving the distortion characteristics.

[0008]

However, in the conventional transmitting apparatus, in order to sufficiently compensate for the distortion characteristic, a training period for outputting a dummy signal from the signal generating means and sequentially identifying an accurate distortion characteristic is required. This is necessary, and if information transmission is started before the end of the training period, it cannot be avoided that distortion remains in the transmission output.

In particular, in a system for transmitting a burst wave in a TDMA system such as a mobile station of a digital MCA system, the transmission interval may reach several hours. Therefore, it is necessary to compensate for variations in the characteristics of the amplifier during the idle period. In this case, distortion cannot be sufficiently compensated immediately after the start of transmission, which may cause interference with adjacent channels and increase in transmission error rate. This is particularly problematic for amplitude values with a low probability of occurrence because the frequency of updating the distortion value is low.

[0010] The present invention has been made in view of the above problems, and has as its object to provide a transmission device capable of compensating nonlinear characteristics with high accuracy.

[0011]

According to a first aspect of the present invention, there is provided a transmission apparatus for generating a transmission signal as shown in the block diagram of FIG. 1, and a transmission signal generated by the transmission signal generation section. A pre-distortion applying means 12 for applying a predetermined distortion to the signal, a modulation means 13 for modulating an output of the pre-distortion applying means 12 with a predetermined carrier, an amplification means 14 for power-amplifying an output of the modulation means 13, A demodulating means 15 for demodulating the output of the amplifying means 14, an output of the demodulating means 15 and the predistortion applying means 1
2, a first amplitude calculator 17 for calculating the amplitude of the output of the demodulator 15, a distortion calculator 16 for calculating a value representing the distortion included in the output of the amplifier 14 as a difference from the output of the amplifier 2, and a transmission signal generator. A second amplitude calculator 18 for calculating the amplitude of the transmission signal generated in step 11, an output amplitude of the demodulator calculated by the first amplitude calculator 17, and a transmission signal calculated by the second amplitude calculator 18. A predistortion calculating unit for calculating a predetermined distortion given to the transmission signal by the predistortion applying unit based on the amplitude and the value representing the distortion calculated by the distortion calculating unit;

According to a second aspect of the present invention, in the transmission apparatus, the distortion calculating means corrects a delay time based on an output of the predistortion means with respect to an output of the demodulating means input to the distortion calculating means. Including time correction means. In the transmission device according to the third aspect, the predistortion calculating means 12 calculates a value representing a distortion corresponding to the amplitude of the output of the demodulating means 15 calculated by the first amplitude calculating means 17 by the second amplitude calculating means 18. A predetermined predistortion is calculated by interpolating based on the amplitude of the transmission signal thus obtained.

According to a fourth aspect of the present invention, each of the first amplitude calculating means 17 and the second amplitude calculating means 18 calculates a square value of the amplitude value.
2 is the square value of the amplitude of the output of the demodulation unit 15 calculated by the first amplitude calculation unit 17, the square value of the amplitude of the transmission signal calculated by the second amplitude calculation unit 18, and calculated by the distortion calculation unit. The predistortion means 12 calculates a predetermined predistortion added to the transmission signal based on the value representing the distortion.

According to a fifth aspect of the present invention, in the transmission apparatus, the pre-distortion applying means 12 transmits the transmission signal generating means 11
A predetermined predetermined predistortion is also applied to the distortion measurement signal output from.

[0015]

FIG. 3 is a block diagram of an embodiment of the transmitting apparatus according to claim 1, and FIG. 4 is a transmission format diagram.
That is, the transmission is divided into a training period T and a subsequent information transmission period J. (1) Training period During the training period, the transmission signal generator 31 included in the transmission signal generation unit 11 outputs a distortion measurement signal, and switches the switch 322 of the predistortion unit 32 to the multiplication unit 32.
Control is performed on the side of the route that does not pass through No. 1.

The distortion measurement signal is supplied to the D / A converter 3 based on a clock signal oscillated from the clock oscillator 331.
At 32, it is converted to an analog signal. After the band of the analog distortion measurement signal is limited by the filter 333, the analog distortion measurement signal is quadrature-modulated by the quadrature modulator 335 using the quadrature carrier output from the quadrature carrier generator 334, and is added to the amplifier 341. The orthogonal carrier generator 334 and the orthogonal modulator 33
5 constitutes a modulating means.

A part of the transmission output of the amplifier 341 is guided to the quadrature demodulator 351 via the directional coupler 342, and is quadrature demodulated using the output of the quadrature carrier generator 334. Note that the orthogonal carrier generator 334 and the orthogonal demodulator 351 constitute the demodulating means 35. The orthogonally demodulated distortion measurement signal passes through a filter 352 and is converted into a digital signal by an A / D converter 353.

Note that the D / A converter 332 and the A / D converter 353 operate with a clock oscillated from the same clock oscillator 331, in order to secure the same time when calculating distortion. The demodulated signal converted to a digital signal contains a distortion component of the amplifier 341, but is transmitted from the D / A converter 332 to the A / D converter 35.
3 are also multiplied, so that the transmission signal generation unit 3
The gain is adjusted by the constant setting unit 354 and the multiplier 355 so that the distortion measurement signal output from 1 and the peak amplitude value become the same. Note that the gain is adjusted from the directional coupler 342 to A
Any position up to the / D converter 353 may be used.

In the divider 361 constituting the distortion calculating means, the "reciprocal of distortion" is obtained as a "value indicating distortion" from the demodulated signal and the distortion measurement signal whose gain has been adjusted. Here, the reciprocal is obtained because the predistortion applying means 32 is realized by the multiplier 321. The distortion may be obtained, and the pre-distortion applying means may be constituted by a divider. Further, the distortion and the reciprocal of the distortion may be calculated in polar coordinates or in rectangular coordinates.

The calculated "reciprocal of distortion" is stored in the distortion memory 391 constituting the predistortion calculating means. FIG. 5 is a configuration diagram of the distortion memory 391 and the amplitude memory 392. As for the storage address, the “reciprocal of distortion” is obtained in rectangular coordinates, and the real part of the reciprocal of distortion is stored in “N + i” (1 ≦ i ≦ N). In this case, the imaginary part of the reciprocal of the distortion is stored in "2N + i".

The first amplitude calculator 371 constituting the first amplitude calculator calculates the amplitude "A" of the demodulated signal whose gain has been adjusted, and the amplitude "A" corresponds to the address where the "reciprocal of the distortion" is stored. Then, it is stored at the address “i” of the amplitude memory 392. As shown in FIG. 4, the spread of the spectrum of the distortion measurement signal is prevented by returning the distortion measurement signal from the minimum amplitude to the minimum amplitude via the maximum amplitude during the training period.

In this case, if the distortion value is measured in the first half of the distortion measurement signal, the measurement can be performed in the order of increasing amplitude, and the amplitude, the actual distortion part, and the imaginary distortion part can be stored for each measurement point. Thereby, the measurement can be simplified. In addition, by setting the amplitude value of the latter half of the distortion measurement signal to be between the amplitude values of the former half, it is possible to measure the distortion of twice the number of amplitude values in substantially the same training period. (2) Information Transmission Period During the information transmission period, the transmission signal generation unit 31 outputs a transmission signal and controls the switch 322 to pass through the multiplier 321.

The amplitude value "B" of the transmission signal is calculated by the second amplitude calculator 381 constituting the second amplitude calculation means. From the amplitude values stored in the amplitude memory 392, the amplitude value "
The minimum difference address search unit 393 searches for the amplitude value closest to B ". FIG. 6 is a detailed configuration diagram of the minimum difference address search unit 393. At the start of the search, the address counter a is set to an initial value (for example," 1 "). The address set by the address counter a is output to the amplitude memory 392, and the amplitude value corresponding to the address is read.

The difference calculator b calculates the difference between the amplitude value "A" calculated by the first amplitude calculator 371 and the amplitude value "B" calculated by the second amplitude calculator 381, and calculates the absolute value of the difference. The value is calculated by the value calculator c. When the address set by the address counter a is "1", the absolute value is temporarily stored in the register d. Next, the address counter a is incremented, and the process returns to reading of the amplitude memory 392. If the address is "2" or more, the difference calculation unit e subtracts the stored contents of the register d, and the polarity detection unit f detects the polarity.

If the polarity is negative, the calculated absolute value is stored in the register d, the address counter a is incremented, and the process returns to reading the amplitude memory 392. When the polarity is inverted to positive, the address at that time is latched by the latch unit g, and the process of outputting this address to the address shift unit 394 is completed. FIG. 7 shows the minimum difference address search unit 3
93 is an operation explanatory diagram of FIG. 93, where the horizontal axis represents the address value of the address counter a, the vertical axis represents the amplitude value “A” or “B” in (A), and the amplitude value “A” in (B). The absolute value of the difference from "B", that is, the storage content of the register d is obtained.

In the example shown in FIG. 7, when the address becomes "4", the polarity detector f detects the inversion of the polarity from negative to positive, and the address "4", that is, the address indicating the minimum difference, is obtained.
An address obtained by adding "1" to 3 "is latched. An address shift unit 394 calculates an address of the distortion memory 391 corresponding to the latched address.

In the case of the above example, the real part is "4" and "N-
"1" is added to "N + 3", and the imaginary part is added to "4" by "2N-1".
Is added to obtain "2N + 3". "Reciprocal of distortion" stored in distortion memory 391 by these two addresses
Is read out, and the burst signal is multiplied by the multiplier 321. After that, the digital signal is converted into an analog signal by a D / A converter 332, band-limited by a filter 333, quadrature-modulated by a quadrature modulator 335 using an output of a quadrature carrier generator 334, amplified by an amplifier 341, and It is output via the sex coupler 342.

FIG. 8 is an explanatory diagram of the distortion compensation method according to claim 1, wherein the horizontal axis represents the transmission signal X output from the transmission signal generator 31 and the vertical axis represents the output signal Y of the amplifier 341. The solid line indicates the case where the characteristic of the amplifier 341 is linear, and the broken line indicates the case where the characteristic of the amplifier 341 is non-linear. Assuming that the distortion measurement signal output from the transmission signal generation unit 31 during the training period is X _T (i) (i = 0 to 4),
Since the distortion measurement signal X _T (i) is directly input to the amplifier, the output of the amplifier 341 becomes Y _T (i).

Therefore, the “reciprocal of distortion” η (i) calculated by the divider 361 is X _T (i) / Y _T (i), which is stored in the distortion memory 391. If the transmission signal output from the transmission signal generation unit 31 to the information transmission period and X _B, i = 3 is latched in the minimum difference address search unit 393. Accordingly, X _B is multiplied by η (3) in multiplier 321, and η (3) · X _B is input to amplifier 341, and output Y _B is output from amplifier 341.

[0030] as it is the original transmission signal X _B amplifier 341
Since when inputting the output should be Z _B is output to, it is possible to significantly improve the non-linearity. First
According to the transmitting device of the present invention, the nonlinearity of the amplifier 341 can be corrected.
D / A converter 33 between one input, that is, the distortion measurement signal generated by burst signal generation section 31 and the demodulated signal.
2, filter 333, quadrature modulator 335, amplifier 34
1. There is a time difference required to pass through the directional coupler 342, the quadrature demodulator 351, the filter 353, and the A / D converter 353.

Therefore, when the time difference is large, X
“Reciprocal of distortion” η calculated from _T (i) / Y _T (i)
An error may occur in (i). FIG. 9 is a configuration diagram of a transmission device for solving the above problem. That is, in the transmission device according to the second aspect, the clock for shifting the clock signal corresponding to the time difference between the clock oscillator 331 and the A / D converter 353 of the transmission device according to the first aspect. A shifter 356 is provided.

As described above, by adjusting the time difference between the two signals input to the divider 361 so that they coincide with each other,
The accuracy of calculating the reciprocal of the distortion can be improved. However, "inverse distortion" eta (i) is possible to avoid errors in the distortion correction in the case because defined as a sample value, the burst signal X _B outputted from the burst signal generating portion 31 is an intermediate value Can not.

FIG. 10 is a block diagram of a transmitter for solving the above-mentioned problem. The accuracy of the predistortion calculation is calculated by interpolating between two “reciprocals of distortion” η (i) and η (i + 1). The interpolator 395 for improving the distortion is a distortion memory 391 and a multiplier 321.
Is installed between In the present embodiment, the minimum address search unit 393 includes, from the stored contents of the amplitude memory 392, an address having the closest amplitude value B1 on the side smaller than the amplitude value "B" of the burst signal and the closest amplitude value B1 on the larger side.
Search for two of the addresses that have a 2.

Based on the two addresses obtained, the “reciprocal number of distortion” η (i) and η (i +
Read out 1). Then, the reciprocal value η of the distortion is calculated by the interpolation unit 395 by the following equation. η = (1−P) · η (i) + P · η (i + 1) Here, P = (B−B1) / (B2−B1) As described above, the calculation accuracy of the predistortion by the interpolation processing by the interpolator 395 Can be improved.

In the transmitting apparatus described above, the amplitude of the distortion measurement signal or the burst signal generated by the first amplitude calculator 371 for calculating the amplitude “A” of the gain-adjusted demodulated signal and the burst signal generator 31 is calculated. A second amplitude calculator 381 for calculation is required. However, the amplitude calculator is a squarer that squares the real part signal and the imaginary part signal,
Although it is composed of an adder for adding two square values and a square root for square rooting the added value, there is a drawback that the configuration of the square rooter is complicated and the apparatus scale becomes large.

In order to solve this problem, the square root extractor is omitted, and an amplitude 2 comprising a squarer and an adder is used instead of the amplitude calculator.
It is also possible to store the square value of the amplitude in the amplitude memory 392 by using the square calculation unit and execute the minimum difference address search unit 393 with the square value of the amplitude. As a result, although the compensation accuracy of the nonlinearity slightly deteriorates, the apparatus can be simplified.

In the transmission apparatus described above, during the training period, the “reciprocal of distortion” is stored without adding predistortion to the distortion measurement signal. FIG. 11 is a characteristic diagram of the amplifier. In the case of the class AB, the output signal is output even when the input signal is small, but when the nonlinearity is large like the class C amplifier, the output signal is output when the input signal is small. No signal is generated.

That is, when the distortion measurement signal is small, the pre-distortion is not applied, so that the spectrum is widened and the interference to the adjacent channel is easily caused. Further, since no output is generated in a region where the amplitude of the distortion measurement signal is small, the distortion measurement efficiency is deteriorated. According to a fifth aspect of the present invention, there is provided a transmission device comprising: a distortion memory 391;
2, representative characteristic data measured in advance is written, and predistortion is also applied to the distortion measurement signal.

Thus, even when an amplifier having a large nonlinearity is used, the nonlinearity can be corrected. It should be noted that 1 is added to the pre-distortion for the second and subsequent distortion measurement signals.
As in the case of the first time, representative characteristic data may be used.
The characteristic data measured in the second burst transmission may be used.

In this case, the switch 322 inside the predistortion applying means 32 becomes unnecessary. Thus, the spread of the spectrum of the distortion measurement signal can be reduced, and the accuracy of measuring the reciprocal of the distortion can be improved. FIG. 12 is a graph showing the effect of the transmitting apparatus according to claim 5, wherein the horizontal axis represents frequency,
The spectrum is plotted on the vertical axis.

That is, when the distortion compensation is not performed, the peripheral spectrum has a considerable size, but it can be understood that the peripheral spectrum is suppressed by performing the distortion compensation. In the transmission apparatus described above, the digital processing before the D / A converter 332 and the digital processing after the A / D converter 353 are performed by a discrete circuit, but the digital processing is performed by a DSP (Digital Sig).
nal Processor).

FIG. 13 shows DS for digital signal processing.
It is a block diagram in case P400 is applied. FIG. 14 is a flowchart of a main routine executed by the DSP 400. In step S1, distortion measurement processing is executed.
In step S2, an information sending process is executed.

FIG. 15 is a detailed flowchart of the distortion measuring process executed in step S1, which is performed in step S101.
, An index i indicating the number of times of performing distortion measurement is set to an initial value “0”. In step S102, a distortion measurement signal X _T (i) is generated.
The A / A converter 332 converts the distortion measurement signal X _T (i) into an analog signal and outputs it.

In step S104, the demodulated signal Y
_T (i) is converted into a digital signal by the A / D converter 353 and read. In step S105, the square value E of the amplitude of the demodulated signal Y _T (i) whose gain has been adjusted is calculated, and in step S106, E is stored in the amplitude memory 39.
Stored in 2. In step S107, “the reciprocal of the distortion”
η (i) is calculated as X _T (i) / Y _T (i), and is stored in the distortion memory 391 in step S108.

In step S109, the index i
Is greater than or equal to a predetermined value N. If a negative determination is made, the index i is incremented in step S110, and the process returns to step S102. Step S109
When a positive determination is made in, this process ends.
FIG. 16 is a flowchart of the information sending process executed in step S2. In step S21, an index j indicating time is set to an initial value "0".

In step S22, the burst signal X _B
(J) is generated, and the square value F of the amplitude of the burst signal X _B (j) is calculated in step S23. Step S2
Calculating the predistortion D at 4, the burst signal X _B (j) and the predistortion D and multiplied to the burst output signal to impart a predistorted D in the burst signal X _B (j) in step S25 Calculate Y _B (j).

In step S26, the burst output signal Y _B (j) is output from the D / A converter 332. Then, in step S27, the index j is equal to the predetermined value M.
It is determined whether this is the case. If a negative determination is made, the index j is incremented in step S27, and the process returns to step S22.

If an affirmative determination is made in step S27, this process ends. FIG. 17 is a flowchart of the predistortion calculating process executed in step S24. In step S241, the index k is set to the initial value “0”.
Set to. In step S242, the index k
Is determined to be “0”, and if the determination is affirmative, the initial value Δ (0) of the deviation Δ of the amplitude square value is determined in step S243.
Is calculated based on the following equation, and the routine proceeds to step 246.

Δ (0) = | E (0) -F (j) | If a negative determination is made in step S242, then step S
Proceeding to 245, the deviation Δ (k) of the amplitude square value is calculated by the following equation. Δ (k) = | E (k) −F (j) | In step S246, whether the deviation Δ (k) of the amplitude square value is negative, that is, the level of the burst signal X _B (j) is N
It is determined whether or not the k-th level of the distortion measurement signals is approaching.

When an affirmative determination is made in step S246, the index k is incremented in step S247, and the flow returns to step S242. Step S2
When a negative determination is made in 46, the process proceeds to step S248, and P is calculated based on the following equation. P = [F (j) -E (k-1)] / [E (k) -E (k
-1)] In step S249, the predistortion D is calculated by the following equation, and the process ends.

D = (1−P) · E (k−1) + PE · (k) That is, by applying the DSP, it is possible to reduce the size and cost of the transmission device.

[0052]

According to the transmission apparatus of the first aspect, the distortion is compensated with high accuracy by performing the distortion compensation calculated on the transmission signal corresponding to the distortion measurement signal having the amplitude closest to the amplitude. It is possible to do. According to the transmission apparatus of the second aspect, it is possible to improve the calculation accuracy of the value representing the distortion by correcting the time difference between the distortion measurement signal and the demodulated signal during the training period.

According to the transmitting apparatus of the third aspect, it is possible to improve the accuracy of distortion compensation by interpolating the distortion compensation value according to the amplitude of the transmission signal. According to the transmitting apparatus of the fourth aspect, the configuration of the transmitting apparatus can be simplified by using the square value of the amplitude instead of the amplitude of the transmission signal and the demodulated signal.

According to the transmitting apparatus of the fifth aspect, it is possible to use an amplifier having a large nonlinearity as the amplifier.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a transmission device according to claim 1;

FIG. 2 is a configuration diagram of a conventional transmission device.

FIG. 3 is a configuration diagram of an embodiment of a transmission device according to claim 1;

FIG. 4 is a transmission format diagram.

FIG. 5 is a configuration diagram of a distortion memory and an amplitude memory.

FIG. 6 is a detailed configuration diagram of a minimum difference address search unit.

FIG. 7 is a diagram illustrating the operation of a minimum difference address search unit.

FIG. 8 is an explanatory diagram of a distortion compensation method.

FIG. 9 is a configuration diagram of an embodiment of a transmission device according to claim 2;

FIG. 10 is a configuration diagram of an embodiment of a transmission device according to claim 3;

FIG. 11 is a characteristic diagram of the amplifier.

FIG. 12 is a graph showing an effect of the transmission device according to claim 5;

FIG. 13 is a configuration diagram when a DSP is applied.

FIG. 14 is a flowchart of a main routine.

FIG. 15 is a flowchart of a distortion measurement process.

FIG. 16 is a flowchart of an information sending process.

FIG. 17 is a flowchart of a predistortion calculation process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Signal generation means 12 ... Predistortion means 13 ... Modulation means 14 ... Amplification means 15 ... Demodulation means 16 ... Distortion calculation means 17 ... First amplitude calculation means 18 ... Second amplitude calculation means 19 ... Predistortion calculation means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 27/36 H03F 1/32 H04L 27/20

Claims (5)

(57) [Claims] A transmission signal generation unit for generating a transmission signal; a predistortion applying unit for applying a predetermined predistortion to the transmission signal generated by the transmission signal generation unit; A modulating unit that modulates the transmission signal to which the predistortion is applied with a predetermined carrier; an amplifying unit that power-amplifies the transmission signal modulated by the modulating unit; a demodulating unit that demodulates an output of the amplifying unit; Distortion calculating means for calculating a value representing the distortion included in the output of the amplifying means based on the output of the means and the output of the predistortion means; and a first amplitude calculating means for calculating the amplitude of the output of the demodulating means. A second amplitude calculator for calculating the amplitude of the transmission signal generated by the transmission signal generator; an output amplitude of the demodulator calculated by the first amplitude calculator; and the second amplitude calculator. Transmission signal calculated by And a predistortion calculating unit that calculates a predetermined predistortion added to a transmission signal in the predistortion applying unit based on the amplitude representing the distortion calculated by the distortion calculating unit, A transmitting device provided. 2. The distortion calculating means includes delay time correcting means for correcting a delay time based on an output of the predistortion means with respect to an output of the demodulation means input to the distortion calculating means. The transmission device according to claim 1. 3. The predistortion calculating means transmits a value representing a distortion corresponding to the amplitude of the output of the demodulating means calculated by the first amplitude calculating means to a value calculated by the second amplitude calculating means. The transmitting apparatus according to claim 1, wherein a predetermined predistortion is calculated by interpolating based on a signal amplitude. 4. The first amplitude calculation means and the second amplitude calculation means each calculate a square value of an amplitude value, and the predistortion calculation means is configured to calculate a square value of the first amplitude calculation means. The calculated square value of the amplitude of the output of the demodulation means, the square value of the amplitude of the transmission signal calculated by the second amplitude calculation means, and the value representing the distortion calculated by the distortion calculation means The transmitting apparatus according to any one of claims 1 to 3, wherein a predetermined predistortion added to the transmission signal by the predistortion applying unit is calculated based on the predistortion. 5. The pre-distortion applying unit applies a predetermined pre-distortion to a distortion measurement signal output from the transmission signal generation unit during a distortion measurement period. The transmission device according to any one of claims 1 to 4.