Modulator

Abstract

This modulator comprises: an energy distribution unit that distributes, at a predetermined ratio corresponding to a desired level for each side wave component, a signal wave to be transmitted on which integration or operation approximately corresponding to integration has been performed; an even-numbered term side wave generation unit that generates one or more signals each having an even number-th side wave component on the basis of a carrier signal and the signal wave distributed at the predetermined ratio by the energy distribution unit; and an odd-numbered term side wave generation unit that generates one or more signals each having an odd number-th side wave component on the basis of the carrier signal and the signal wave distributed at the predetermined ratio by the energy distribution unit.　

Description

Modulator

[0001] The present invention relates to a modulator.

[0002] Conventionally, an Armstrong modulator has been used as a modulator. The Armstrong modulator has a simple configuration and displaces the phase or frequency of a carrier wave. That is, the Armstrong modulator performs phase modulation or frequency modulation. FIG. 6 is a diagram showing an example of the configuration of a modulator 90 of the prior art. The modulator 90 is an example of an Armstrong modulator configured as a frequency modulator, and an integrator is arranged at the input section of the signal wave.

[0003] The modulator 90 includes a carrier signal generating unit 91, a dividing unit 92, a phase adjusting unit 93, an integrator 94, a multiplier 95, and a multiplexer 96. The carrier signal generating unit 91 outputs a carrier signal. The dividing unit 92 divides the carrier signal output by the carrier signal generating unit 91 into two. One of the divided carrier signals is input to a phase adjusting unit 93. The phase adjusting unit 93 performs a phase rotation of 90 degrees on the input carrier signal and then outputs the phase rotation to the multiplier 95. Here, the phase adjusting unit 93 may be configured to be disposed between the dividing unit 92 and the multiplier 95 as shown in FIG. 6 , or may be disposed between the dividing unit 92, which is the output of the other dividing unit 92, and the multiplexer 96. When the phase adjusting unit 93 is disposed between the dividing unit 92 and the multiplexer 96, the phase rotation in the phase adjusting unit 93 is minus 90 degrees. The integrator 94 integrates the input carrier signal and outputs the integrated signal wave to the multiplier 95. The multiplier 95 multiplies the phase-rotated carrier signal by the integrated signal wave and outputs the multiplied signal to the combiner 96. The combiner 96 outputs a signal obtained by combining the signal output from the multiplier 95 with the other carrier signal distributed by the distributor 92.

[0004] Ryozo Nagahama, "On the Phase Modulation Method for VHF-FM," Hitachi Hyoronsha, Special Issue No. 3, pp. 71-82. Toshiaki Shimoba et al., "Optical Video Distribution Technology Using FM Batch Conversion Method," Institute of Electronics, Information and Communication Engineers, IEICE Technical Report, vol. 119, no. 323, CS2019-84, pp. 97-101, December 2019.

[0005] In a conventional modulator 90, the output signal from a carrier signal generator 91 is split into two, one of which is phase-rotated by 90 degrees using a phase shifter (phase adjustment unit 93), and then this signal is multiplied by a signal wave in a multiplier (multiplication unit 95).The signal multiplied by the multiplier 95 is then added to the other split output signal to obtain a pseudo carrier signal and a first sideband signal.With this configuration, it is not possible to obtain second or subsequent sideband components.

[0006] An ideal frequency modulation signal waveform has the first and subsequent sidewave components (the second, third, fourth, etc. sidewaves in FIG. 7) as shown in FIG. 7. In other words, the absence of a sidewave indicates a deterioration in the distortion characteristics of the signal. Thus, conventional Armstrong modulators have had the problem of degraded distortion characteristics.

[0007] In view of the above circumstances, an object of the present invention is to provide a technique capable of suppressing deterioration of distortion characteristics of a modulated output signal.

[0008] One aspect of the present invention is a modulator comprising: an energy distribution unit that distributes a signal wave to be transmitted, which has been integrated or subjected to an operation approximately equivalent to integration, at a predetermined ratio corresponding to a desired level for each sideband component; an even-term sideband generation unit that generates one or more signals having even-numbered sideband components based on a carrier signal and the signal wave distributed at the predetermined ratio by the energy distribution unit; and an odd-term sideband generation unit that generates one or more signals having odd-numbered sideband components based on the carrier signal and the signal wave distributed at the predetermined ratio by the energy distribution unit.

[0009] According to the present invention, it is possible to suppress deterioration of the distortion characteristics of the modulated output signal.

[0010] FIG. 1 is a configuration diagram of a modulator. FIG. 2 is a configuration diagram of a modulator in an embodiment. FIG. 3 is a diagram for explaining an ideal FM signal waveform according to a value of a modulation index β in an embodiment. FIG. 4 is a diagram showing an example of a power table held by an information output unit in an embodiment. FIG. 5 is a diagram for explaining the mechanism of an energy distribution unit in an embodiment. FIG. 6 is a diagram showing an example of the configuration of a modulator of the prior art. FIG. 7 is a diagram showing an example of an ideal signal waveform of a phase modulation method.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] Before describing the specific configuration of the present invention, one possible configuration for solving the problems of the present invention will be described. Fig. 1 is a configuration diagram of a modulator 10a. The modulator 10a includes a carrier signal generating section 101, a dividing section 102, a phase adjusting section 103, a dividing section 104, a level adjusting section 105, a dividing section 106, a dividing section 107, an integrator 108, a dividing section 109, a dividing section 110, a dividing section 111, an odd-term sideband generating section 112, an even-term sideband generating section 113, a combining section 114, and a phase adjusting section 115.

[0013] The carrier signal generating unit 101 outputs a carrier signal. The dividing unit 102 inputs the carrier signal output by the carrier signal generating unit 101. The dividing unit 102 divides the input carrier signal. For example, the dividing unit 102 divides the input carrier signal into two. In this case, the dividing unit 102 divides the carrier signal into a first path and a second path. The phase adjusting unit 103 is connected to the first path divided by the dividing unit 102, and the dividing unit 104 is connected to the second path divided by the dividing unit 102. The carrier signal divided by the dividing unit 102 is input to the phase adjusting unit 103 and the dividing unit 104.

[0014] The distribution unit 104 receives the carrier signal distributed by the distribution unit 102. The distribution unit 104 distributes the received carrier signal. For example, the distribution unit 104 distributes the received carrier signal into two paths. In this case, the distribution unit 104 distributes the carrier signal to a first path and a second path. The level adjustment unit 105 is connected to the first path distributed by the distribution unit 104, and the distribution unit 110 is connected to the second path distributed by the distribution unit 104. The carrier signal distributed by the distribution unit 104 is input to the level adjustment unit 105 and the distribution unit 110.

[0015] The level adjustment unit 105 adjusts the level of the input carrier signal and outputs the level-adjusted carrier signal to the multiplexer 114. The level adjustment unit 105 is realized by, for example, a power amplifier or an attenuator.

[0016] The phase adjustment unit 103 receives the carrier signal distributed by the distribution unit 102. The phase adjustment unit 103 adjusts the phase of the input carrier signal. For example, the phase adjustment unit 103 rotates the phase of the input carrier signal by 90 degrees. The carrier signal whose phase has been adjusted by the phase adjustment unit 103 is input to the distribution unit 106.

[0017] Here, the phase adjustment unit 103 uses a phase shifter to rotate the phase of the input signal by 90 degrees (for example, if the carrier signal is cos, it is changed to sin), but it does not have to be a phase shifter as long as it is a device that can adjust the phase; for example, a delay device may be used, or the wiring path length may be adjusted to change the phase by 90 degrees.

[0018] The dividing unit 106 receives the carrier signal whose phase has been adjusted by the phase adjusting unit 103. The dividing unit 106 divides the received phase-adjusted carrier signal into two or more paths. The carrier signals divided by the dividing unit 106 are input to the odd-term sideband generating unit 112.

[0019] The integrator 108 receives a signal wave. The signal wave is a signal to be transmitted. The integrator 108 integrates the received signal wave. The signal wave integrated by the integrator 108 is input to the distributor 107.

[0020] The distributor 107 receives the signal wave integrated by the integrator 108. The distributor 107 distributes the received integrated signal wave. For example, the distributor 107 distributes the received signal wave into two paths. In this case, the distributor 107 distributes the signal wave into a first path and a second path. The distributor 111 is connected to the first path distributed by the distributor 107, and the phase adjuster 115 is connected to the second path distributed by the distributor 107. The integrated signal wave distributed by the distributor 107 is input to the phase adjuster 115 and the distributor 111.

[0021] The divider 111 receives the integrated signal wave distributed by the divider 107. The divider 111 distributes the received integrated signal wave to two or more paths. The integrated signal wave distributed by the divider 111 is input to the odd-term sideband generating unit 112.

[0022] The odd-term sidewave generating unit 112 generates odd-term sidewaves. The odd-term sidewaves are odd-numbered upper and lower sidewaves, such as the first upper sidewave (+J1), the first lower sidewave (-J1), the third upper sidewave (+J3), the third lower sidewave (-J3), .... The odd-term sidewave generating unit 112 is composed of one or more multipliers 120, one or more multiplier units 121, and one or more level adjuster units 122.

[0023] For example, if the odd-term sidewave generating unit 112 is to generate odd-numbered sidewaves up to the third sidewave (for example, the first and third sidewaves), the odd-term sidewave generating unit 112 is provided with two multipliers 120, two multipliers 121, and two level adjusters 122. Note that the multiplier 120-1 (multiplier (1x) in FIG. 1 ), which multiplies the frequency of a signal wave and outputs it, does not have to be provided because it is configured to output the input signal without any processing. In this case, the odd-term sidewave generating unit 112 is provided with one multiplier 120, and two multipliers 121 and two level adjusters 122.

[0024] Multiplier 120 converts each signal wave distributed by distributor 111 to a different odd multiple (n times) of frequency and outputs the converted signal wave. For example, if three multipliers 120 (N=3) are provided, multiplier 120-1 converts the signal wave distributed by distributor 111 to a frequency of 1x and outputs the converted signal wave, multiplier 120-2 converts the signal wave distributed by distributor 111 to a frequency of 3x and outputs the converted signal wave, and multiplier 120-3 converts the signal wave distributed by distributor 111 to a frequency of 5x and outputs the converted signal wave. In this way, each multiplier 120 converts the signal wave to a frequency of nx and outputs the converted signal wave, where n is an odd number greater than or equal to 1.

[0025] The multiplier 121 multiplies the signal wave with n times the frequency output from the multiplier 120 by the carrier signal distributed by the distributor 106. The multiplier 121 outputs the signal obtained by the multiplication to the level adjuster 122.

[0026] The level adjustment unit 122 adjusts the level of the input signal and outputs the level-adjusted signal to the multiplexing unit 114. The level adjustment unit 122 is realized by, for example, a power amplifier or an attenuator.

[0027] The dividing unit 110 receives the carrier signal divided by the dividing unit 104. The dividing unit 110 divides the received carrier signal into two or more paths. The carrier signal divided by the dividing unit 110 is input to the even-term sideband generating unit 113.

[0028] The phase adjustment unit 115 is disposed between the distribution unit 107 and the distribution unit 109. The phase adjustment unit 115 receives the integrated signal wave distributed by the distribution unit 107. The phase adjustment unit 115 adjusts the phase of the input integrated signal wave. For example, the phase adjustment unit 115 rotates the phase of the input integrated signal wave by 90 degrees. The signal wave whose phase has been adjusted by the phase adjustment unit 115 is input to the distribution unit 109.

[0029] Here, the phase adjustment unit 115 uses a phase shifter to rotate the phase of the input signal by 90 degrees (for example, changing a signal wave that is sin to cos), but it does not have to be a phase shifter as long as it is a device that can adjust the phase; for example, a delay device may be used, or the wiring path length may be adjusted to change the phase by 90 degrees.

[0030] The dividing unit 109 receives the signal wave whose phase has been adjusted by the phase adjusting unit 115. The dividing unit 109 divides the input signal wave whose phase has been adjusted into two or more paths. The signal wave divided by the dividing unit 109 is input to the even-term sideband generating unit 113.

[0031] The even-term sidewave generating unit 113 generates even-term sidewaves. The even-term sidewaves are even-numbered upper and lower sidewaves, such as the second upper sidewave (+J2), the second lower sidewave (-J2), the fourth upper sidewave (+J4), the fourth lower sidewave (-J4), .... The even-term sidewave generating unit 113 is composed of one or more multipliers 130, one or more multiplier units 131, and one or more level adjuster units 132.

[0032] For example, if the even-term sideband generating unit 113 is to generate even-numbered sidebands up to the fourth sideband (e.g., the second sideband and the fourth sideband), the even-term sideband generating unit 113 includes two multipliers 130, two multipliers 131, and two level adjusters 132.

[0033] Multiplier 130 converts each signal wave distributed by distributor 109 into a frequency that is a different even multiple (m times) and outputs the converted signal wave. For example, if three multipliers 130 are provided, multiplier 130-1 doubles the frequency of the signal wave distributed by distributor 109 and outputs it, multiplier 130-2 quadruples the frequency of the signal wave distributed by distributor 109 and outputs it, and multiplier 130-3 quadruples the frequency of the signal wave distributed by distributor 109 and outputs it. In this way, each multiplier 130 converts the signal wave into an m-times frequency and outputs it, where m is an even number greater than or equal to 2.

[0034] The multiplier 131 multiplies the signal wave with m times the frequency output from the multiplier 130 by the carrier signal distributed by the distributor 110. The multiplier 131 outputs the signal obtained by the multiplication to the level adjuster 132.

[0035] The level adjustment unit 132 adjusts the level of the input signal and outputs the level-adjusted signal to the multiplexing unit 114. The level adjustment unit 132 is realized by, for example, a power amplifier or an attenuator.

[0036] The multiplexer 114 multiplexes the signal output from the level adjuster 105 , the signals output from the odd-term sideband generator 112 , and the signals output from the even-term sideband generator 113 .

[0037] The spectrum of a phase-modulated waveform (FM waveform) (such as the waveform shown in FIG. 7 ) is uniquely determined once parameters such as the modulation index are determined, and the amplitude of each sidewave is also uniquely determined. Therefore, as an example of a level adjustment method in each of the level adjustment units 105, 122, and 132 in the above-described embodiment, each of the level adjustment units 105, 122, and 132 adjusts the level so that it is equal to the magnitude of the ideal amplitude component of each sidewave.

[0038] (Operation of Modulator) With the above configuration, the modulator 10a operates as follows. In explaining the operation of the modulator 10a, it is assumed that the carrier signal generated by the carrier signal generating unit 101 is f ｃ =A ｃ cos(ω ｃ t), and the signal wave is f ｓ = cos(ω ｓ t).

[0039] The carrier signal generating section 101 of the modulator 10a generates a carrier signal f ｃ =A ｃ cos(ω ｃ t) is output from the carrier signal generating unit 101. ｃ =A ｃ cos(ω ｃt) is divided by the dividing unit 102 and input to the phase adjusting unit 103 and dividing unit 104. The carrier signal f ｃ =A ｃ cos(ω ｃ t) is distributed by the distribution unit 104 and input to the level adjustment unit 105 and distribution unit 110.

[0040] The level adjustment unit 105 adjusts the input carrier signal f ｃ =A ｃ cos(ω ｃ t) and outputs it. For the sake of simplicity, the output of the level adjustment unit 105 may be expressed as [A]. That is, [A] = signal K ０ cos(ω ｃ t). Note that K ０ represents the amplitude after adjustment. ０ cos(ω ｃ t) corresponds to the carrier wave (J0).

[0041] The phase adjustment unit 103 adjusts the phase of the input carrier signal f ｃ =A ｃ cos(ω ｃ t) by rotating the phase of the carrier signal f ｃ =-A ｃ sin(ω ｃ t) by the phase adjustment unit 103. ｃ =-A ｃ sin(ω ｃ t) is distributed by the distributor 106 and input to each multiplier 121 of the odd-term sideband generating unit 112. For example, if the odd-term sideband generating unit 112 includes three multipliers 121, the distributor 106 divides the carrier signal f ｃ =-A ｃ sin(ω ｃ t) to three paths leading to the three multipliers 121. As a result, each multiplier 121 receives a carrier signal f ｃ =-A ｃ sin(ω ｃ t) is input.

[0042] The carrier signal f input to the distribution unit 110 ｃ =Aｃ cos(ω ｃ t) is distributed by the distributor 110 and input to each multiplier 131 of the even-term sideband generating unit 113. For example, if the even-term sideband generating unit 113 includes three multipliers 131, the distributor 110 divides the carrier signal f ｃ =A ｃ cos(ω ｃ t) to three paths leading to the three multipliers 131. As a result, each multiplier 131 receives a carrier signal f ｃ =A ｃ cos(ω ｃ t) is input.

[0043] The signal wave f input to the modulator 10 ｓ = cos(ω ｓ t) is input to the integrator 108. The integrator 108 converts the input signal wave f ｓ = cos(ω ｓ t), the signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ The signal wave f integrated by the integrator 108 is converted into ｓ = (1 / ω ｓ ) sin(ω ｓ t) is divided by dividing section 107 and input to dividing section 111 and phase adjusting section 115.

[0044] The signal wave f input to the distribution unit 111 ｓ = (1 / ω ｓ ) sin(ω ｓ t) is divided by the dividing unit 111 and input to each multiplier 120 of the odd-term sideband generating unit 112. For example, if the odd-term sideband generating unit 112 includes three multipliers 120, the dividing unit 111 divides the signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ t) to three paths leading to the three multipliers 120. As a result, each multiplier 120 receives a signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ t) is input.

[0045] Each multiplier 120 multiplies the input signal wave f ｓ= (1 / ω ｓ ) sin(ω ｓ t) to a frequency that is a different odd multiple and outputs the frequency to the subsequent multiplier 121. For example, the multiplier 120-1 multiplies the input signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ t) is multiplied by 1 to produce a signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ For example, the multiplier 120-N multiplies the input signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ t) is multiplied by n to produce a signal wave f ｓ = (1 / ω ｓ ) sin(nω ｓ t) to the subsequent multiplication unit 121-N.

[0046] The multiplication units 121-1 to 121-N multiply the carrier signal f distributed by the distribution unit 106. ｃ =-A ｃ sin(ω ｃ t), the signal wave f output from the multipliers 120-1 to 120-N ｓ = (1 / ω ｓ ) sin(ω ｓ t) ~ (1 / ω ｓ ) sin(nω ｓ t), where N is an integer equal to or greater than 1. For example, the multiplier 121-1 multiplies the carrier signal f ｃ =-A ｃ sin(ω ｃ t), the signal wave f output from the multiplier 120-1 ｓ = (1 / ω ｓ ) sin(ω ｓ The multiplication unit 121-1 multiplies the signal −(A ｃ / ω ｓ ) sin(ω ｃ t) sin(ω ｓ t) to the level adjustment unit 122-1. ｃ / ω ｓ ) sin(ω ｃ t) sin(ω ｓt) can be transformed into the following equation (1) based on the product-sum formula: cos(ω ｃ +ω ｓ )t corresponds to the first upper side wave (+J1), and -cos(ω ｃ -ω ｓ )t corresponds to the first lower side wave (-J1).

[0047]

[0048] Similarly, the multiplication unit 121-N multiplies the carrier signal f distributed by the distribution unit 106 by ｃ =-A ｃ sin(ω ｃ t), the signal wave f output from the multiplier 120-N ｓ = (1 / ω ｓ ) sin(nω ｓ The multiplication unit 121-N multiplies the signal −(A ｃ / ω ｓ ) sin(ω ｃ t) sin(nω ｓ t) to the level adjustment unit 122-N. ｃ / ω ｓ ) sin(ω ｃ t) sin(nω ｓ t) can be converted into the following equation (2) based on the product-sum formula: cos(ω ｃ +nω ｓ )t corresponds to the n-th upper side wave (+Jn), and -cos(ω ｃ -nω ｓ )t corresponds to the nth lower side wave (-Jn).

[0049]

[0050] Level adjustment units 122-1 to 122-N adjust the amplitude levels of the signals output from multiplication units 121-1 to 121-N and output the adjusted levels. For example, level adjustment unit 122-1 adjusts the amplitude level of the signal output from multiplication unit 121-1 and outputs the adjusted levels. For the sake of simplicity in the description of this configuration, the output of level adjustment unit 122-1 is expressed as [C １ ] may also be expressed as [C １] is expressed as the following formula (3). １ represents the amplitude after adjustment.

[0051]

[0052] Similarly, the level adjustment unit 122-N adjusts the amplitude level of the signal output from the multiplication unit 121-N and outputs the adjusted signal. For the sake of simplicity, in this configuration, the output of the level adjustment unit 122-N is expressed as [C ｎ ] may also be expressed as [C ｎ ] is expressed as the following formula (4). ｎ represents the amplitude after adjustment.

[0053]

[0054] The phase adjustment unit 115 adjusts the signal wave f divided by the dividing unit 107. ｓ = (1 / ω ｓ ) sin(ω ｓ t) by rotating the phase of the signal wave f ｓ = (1 / ω ｓ ) cos(ω ｓ t) is converted into a signal wave f ｓ = (1 / ω ｓ ) cos(ω ｓ t) is distributed by the distributor 109 and input to each multiplier 130 of the even-term sideband generating unit 113. For example, if the even-term sideband generating unit 113 includes three multipliers 130, the distributor 109 divides the signal wave f ｓ = (1 / ω ｓ ) cos(ω ｓ t) to three paths leading to the three multipliers 130. As a result, each multiplier 130 receives a signal wave f ｓ = (1 / ω ｓ ) cos(ω ｓ t) is input.

[0055] Each multiplier 130 multiplies the input signal wave f ｓ = (1 / ω ｓ ) cos(ω ｓt) is multiplied by an even number and output to the subsequent multiplier 131. For example, the multiplier 130-1 multiplies the input signal wave f ｓ = (1 / ω ｓ ) cos(ω ｓ t) to double the frequency of the signal wave f ｓ = (1 / ω ｓ ) cos(2ω ｓ The multiplier 130-M outputs the input signal wave f ｓ = (1 / ω ｓ ) cos(ω ｓ t) is multiplied by m to produce a signal wave f ｓ = (1 / ω ｓ ) cos(mω ｓ t) to the subsequent multiplication unit 131-M, where M is an integer of 1 or greater.

[0056] The multiplication units 131-1 to 131-M multiply the carrier signal f distributed by the distribution unit 110. ｃ =A ｃ cos(ω ｃ t), the signal wave f output from the multipliers 130-1 to 130-M ｓ = (1 / ω ｓ ) cos(2ω ｓ t) ~ (1 / ω ｓ ) cos(mω ｓ For example, the multiplier 131-1 multiplies the carrier signal f ｃ =A ｃ cos(ω ｃ t), the signal wave f output from the multiplier 130-1 ｓ = (1 / ω ｓ ) cos(2ω ｓ The multiplication unit 131-1 multiplies the signal (A ｃ / ω ｓ ) cos(ω ｃ t) cos(2ω ｓ t) to the level adjustment unit 132-1. ｃ / ω ｓ ) cos(ω ｃ t) cos(2ω ｓt) can be transformed into the following equation (5) based on the product-sum formula: cos(ω ｃ +2ω ｓ )t corresponds to the second upper side wave (+J2), and cos(ω ｃ -2ω ｓ )t corresponds to the second lower side wave (-J2).

[0057]

[0058] Similarly, the multiplication unit 131-M multiplies the carrier signal f ｃ =A ｃ cos(ω ｃ t), the signal wave f output from the multiplier 130-M ｓ = (1 / ω ｓ ) cos(mω ｓ The multiplication unit 131-M multiplies the signal (A ｃ / ω ｓ ) cos(ω ｃ t) cos(mω ｓ t) to the level adjustment unit 132-M. ｃ / ω ｓ ) cos(ω ｃ t) cos(mω ｓ t) can be transformed into the following equation (6) based on the product-sum formula: cos(ω ｃ +mω ｓ ) t corresponds to the m-th upper side wave (+Jm), and cos(ω ｃ -mω ｓ )t corresponds to the mth lower side wave (-Jm).

[0059]

[0060] The level adjustment units 132-1 to 132-M adjust the amplitude levels of the signals output from the multiplication units 131-1 to 131-M and output the adjusted levels. For example, the level adjustment unit 132-1 adjusts the amplitude level of the signal output from the multiplication unit 131-1 and outputs the adjusted levels. For the sake of simplicity in the explanation of this configuration, the output of the level adjustment unit 132-1 is expressed as [B ２ ] may also be expressed as [B ２ ] is expressed as the following formula (7).２ represents the amplitude after adjustment.

[0061]

[0062] Similarly, the level adjustment unit 132-M adjusts the amplitude level of the signal output from the multiplication unit 131-M and outputs the adjusted signal. ｍ ] may also be expressed as [B ｍ ] is expressed as the following formula (8). ｍ represents the amplitude after adjustment.

[0063]

[0064] The modulator 10a converts [A] obtained by the above processing and [B] ２ ]~[B ｍ ] and [C １ ]~[C ｎ ] are combined by the combiner 114 to generate an FM signal. That is, the FM signal generated by the modulator 10a is expressed by the following equation (9). Note that the amplitude of each sideband of the FM signal is uniquely determined according to the set modulation index.

[0065]

[0066] The modulator 10a configured as described above can suppress degradation of distortion characteristics. Specifically, the reason the modulator 10a has lower distortion than the conventional system is that, when comparing the frequency spectra of the output signal, the modulator 10a is closer to the ideal frequency spectrum than the conventional system. That is, the modulator 10a can generate more sideband signal waveforms than the conventional Armstrong system. The Armstrong system has a simple configuration, allowing for miniaturization and cost reduction, but it can only generate sidebands within the range shown in the box in FIG. 7 (J0, ±J1). Therefore, the Armstrong system differs from the ideal FM signal waveform, which leads to degradation of distortion characteristics and CNR characteristics. In contrast, the modulator 10a not only has the Armstrong system's features of simple configuration, miniaturization, and cost reduction, but can also generate any number of sidebands (J0, ±J1, ±J2, ...). This makes it possible to suppress degradation of distortion characteristics, a problem with the conventional Armstrong system. Furthermore, the CNR characteristics can be improved, which makes it possible to extend the transmission distance and increase the number of modulation levels.

[0067] (Problems with Modulator 10a) In the modulator 10a shown in FIG. 1, the energy of the signal wave output from the integrator 108 is equally divided into each sidewave (J0, ±J1, ±J2, ...) by a divider (e.g., dividers 107, 109, and 111). That is, in the modulator 10a, regardless of the sidewave to be generated, the equally divided energy of the signal wave is input to the odd-term sidewave generating unit 112 and the even-term sidewave generating unit 113. As a result, the level adjusting units 122-1 to 122-N and 132-1 to 132-M in the subsequent stages amplify sidewaves with smaller amplitudes than the desired FM spectrum, which can also amplify thermal noise and the like, potentially degrading signal quality. As such, there is room for improvement in the modulator 10a shown in FIG. 1.

[0068] Therefore, in the present invention, a configuration is described in which the amount of energy division of the signal wave is devised to eliminate the need for level adjustment units 122-1 to 122-N and level adjustment units 132-1 to 132-M provided in modulator 10a, and the SNR of the generated FM waveform is further improved. This will be explained in detail below.

[0069] 2 is a configuration diagram of a modulator 10b according to an embodiment. The modulator 10b includes a carrier signal generating unit 101, a dividing unit 102, a phase adjusting unit 103, a dividing unit 104, a level adjusting unit 105, a dividing unit 106, an integrator 108, a dividing unit 110, an odd-term sideband generating unit 112b, an even-term sideband generating unit 113b, a multiplexing unit 114, an information output unit 150, an energy dividing unit 151, and M phase adjusting units 152.

[0070] 2, the modulator 10b includes an energy divider 151 before the output from the integrator 108 is input to the odd-term sideband generating unit 112b and the even-term sideband generating unit 113b. The modulator 10b uses the energy divider 151 to adjust the amount of signal wave energy to be distributed appropriately according to the magnitude of each sideband, rather than being equally divided. The magnitude of each sideband of an FM signal (= energy distribution on the frequency axis) differs depending on the modulation index β during FM modulation.

[0071] The information output unit 150 receives information on the modulation index β during FM modulation. The information output unit 150 notifies the energy distribution unit 151 of power information according to the input modulation index β. Here, the power information includes power information for each sideband and information on the total value of the power of all sidebands. The information output unit 150 holds a power table in which power information according to the modulation index β is registered, and notifies the energy distribution unit 151 of the power information corresponding to the input modulation index β.

[0072] The energy distributor 151 receives the signal wave integrated by the integrator 108 and the power information output from the information output unit 150 as input. The energy distributor 151 replicates the input integrated signal wave for the number of output ports. The number of output ports may be any number, but there must be at least as many as the number of sidewaves to be generated. Therefore, when the odd-term sidewave generating unit 112b generates two odd-term sidewaves (e.g., first sidewave (±J1) and third sidewave (±J3)) and the even-term sidewave generating unit 113b generates two even-term sidewaves (e.g., second sidewave (±J2) and fourth sidewave (±J4)), the energy distributor 151 must have at least four output ports.

[0073] When duplicating the integrated signal wave for the number of output ports, the energy distributor 151 distributes the energy at an energy ratio based on the power information output from the information output unit 150. For example, the energy distributor 151 allocates a large amount of energy to a sidewave having a large amplitude (or power obtained by squaring the amplitude), and allocates a small amount of energy to a sidewave having a small amplitude. That is, the energy distributor 151 increases the ratio so that a large amount of energy is allocated to a sidewave component having a large amplitude (or power obtained by squaring the amplitude) of each sidewave component, and decreases the ratio so that a small amount of energy is allocated to a sidewave component having a small amplitude (or power obtained by squaring the amplitude).

[0074] The phase adjustment units 152-1 to 152-M are arranged between the energy distribution unit 151 and the even-term sideband generation unit 113b. The phase adjustment units 152-1 to 152-M receive the signal waves whose energies have been adjusted by the energy distribution unit 151. The phase adjustment units 152-1 to 152-M adjust the phases of the input energy-adjusted signal waves. For example, the phase adjustment units 152-1 to 152-M rotate the phases of the input energy-adjusted signal waves by 90 degrees. The signal waves whose phases have been adjusted by the phase adjustment units 152-1 to 152-M are input to the even-term sideband generation unit 113b.

[0075] Here, phase adjustment units 152-1 to 152-M use phase shifters to rotate the phase of the input signal by 90 degrees (for example, changing a signal wave that is sine to cosine), but any device that can adjust the phase does not need to be a phase shifter; for example, a delay device may be used, or the wiring path length may be adjusted to change the phase by 90 degrees.

[0076] The odd-term sidewave generating unit 112b generates odd-term sidewaves. The odd-term sidewave generating unit 112b is composed of one or more multipliers 120 and one or more multipliers 121. As described above, the odd-term sidewave generating unit 112b included in the modulator 10b does not include a level adjusting unit 122. A signal wave whose energy has been adjusted by the energy dividing unit 151 is input to each multiplier 120.

[0077] The even-term sidewave generating unit 113b generates even-term sidewaves. The even-term sidewave generating unit 113b is composed of one or more multipliers 130 and one or more multipliers 131. As such, the even-term sidewave generating unit 113b included in the modulator 10b does not include a level adjusting unit 132. A signal wave whose energy has been adjusted by the energy distributor 151 is input to each multiplier 130.

[0078] FIG. 3 is a diagram for explaining the waveform of an ideal FM signal according to the value of the modulation index β in the embodiment. The upper part of FIG. 3 shows the waveform of an ideal FM signal when the modulation index β=0.5, the middle part of FIG. 3 shows the waveform of an ideal FM signal when the modulation index β=1, and the lower part of FIG. 3 shows the waveform of an ideal FM signal when the modulation index β=5. Here, "+Jm" in FIG. 3 means the name of the sidewave, with "+" meaning that it is at a higher frequency than the carrier wave and "-" meaning that it is at a lower frequency than the carrier wave. Furthermore, "number m" means that it is the mth sidewave counting from the carrier wave. "+Jm" can also be read as "the mth upper sidewave," and both are synonymous. Furthermore, when expressing the amplitude of "+Jm" in the following description, P Ｊｍ It is written as follows.

[0079] As shown in Figure 3, depending on the modulation index β, the amplitude of each sideband may not decrease monotonically with distance from the carrier wave but may oscillate (e.g., β = 5). When generating FM signals for each sideband, it is desirable to distribute the energy of the signal wave according to the magnitude of each sideband. For example, if a low-energy signal wave after multiple branching is used to generate a sideband with a large amplitude, large amplification is required, resulting in degradation of signal quality.

[0080] 4 is a diagram showing an example of a power table held by the information output unit 150 in this embodiment. The power table associates input values ​​with output values. In the power table, the input values ​​are modulation index β values, and the output values ​​are power information for each sideband and total power information for all sidebands. Depending on the input modulation index β value, the information output unit 150 outputs all values ​​registered in the corresponding output value field as power information to the energy distribution unit 151. The power information for each sideband is calculated in advance for each modulation index β value based on the theoretical formula for FM signals. For example, the "total power information for all sidebands" for modulation index β=5 stores a value calculated based on equation (10).

[0081]

[0082] The energy distribution unit 151 replicates the input value f(x) for the number of output ports. The energy (∝f ２ The ratio of (x) is not an equal division, but an energy ratio weighted using a value normalized (divided) by the "power information of each sideband" and the "total value information of the power of all sidebands" output from the information output unit 150. Note that the amount of energy of the input signal and the total amount of energy of the output signal are the same (the amount of energy is conserved between input and output).

[0083] For example, if the number of output ports of the energy distribution unit 151 is two, this means a circuit that generates sidewaves "±J1" and "±J2." If the "power information of each sidewave" output from the information output unit 150 is 5 for "±J1" and 2 for the sidewaves "±J2," and the "total value information of the power of all sidewaves" is 7 (calculated as 5 + 2), the energy distribution unit 151 outputs √(5 / 7) × f(x) to the output port for the sidewaves "±J1," and outputs √(2 / 7) × f(x) to the output port for the sidewaves "±J2."

[0084] Next, the mechanism of the energy distribution unit 151 will be described with reference to FIG. 5. FIG. 5 is a diagram for explaining the mechanism of the energy distribution unit 151 in the embodiment. The energy distribution unit 151 divides the input signal f(t) at an arbitrary energy ratio and generates a plurality of output signals (f １ (t), f ２ (t), ..., f ｎ＿ｍａｘ 5, when the distribution ratio of the energy distribution unit 151 is 2:1:3, the energy distribution unit 151 distributes the energy as √(2 / 6)×f(t), √(1 / 6)×f(t), and √(3 / 6)×f(t), as shown in the output waveform.

[0085] Since the energy distribution unit 151 only divides the input signal by energy, the energy is conserved between the input and output. ２ １ (t) + f ２ ２ (t) +, ..., +f ２ ｎ＿ｍａｘ (t) = f ２ The energy distribution unit 151 can be realized by a commercially available product, for example, a product called a "splitter" that branches television lines in an apartment building or the like.

[0086] (Operation of Modulator 10b) With the above configuration, the modulator 10b operates as follows. In explaining the operation of the modulator 10b, it is assumed that the carrier signal generated by the carrier signal generating unit 101 is f ｃ =A ｃ cos(ω ｃ t), and the signal wave is f ｓ = cos(ω ｓt).

[0087] The carrier signal generating section 101 of the modulator 10b generates a carrier signal f ｃ =A ｃ cos(ω ｃ t) is output from the carrier signal generating unit 101. ｃ =A ｃ cos(ω ｃ t) is divided by the dividing unit 102 and input to the phase adjusting unit 103 and dividing unit 104. The carrier signal f ｃ =A ｃ cos(ω ｃ t) is distributed by the distribution unit 104 and input to the level adjustment unit 105 and distribution unit 110.

[0088] The level adjustment unit 105 adjusts the input carrier signal f ｃ =A ｃ cos(ω ｃ t) and outputs the carrier signal f ｃ =A ｃ cos(ω ｃ The amplitude level of the signal (P Ｊ０ / 2ω ｓ P Ａｌｌ ) and output. As a result, the output of level adjustment unit 105 is expressed as in the following equation (11). Note that equation (11) corresponds to the carrier wave (J0). For the sake of simplicity in the explanation of the configuration shown in FIG. 2, the output of level adjustment unit 105 may also be expressed as [A].

[0089]

[0090] The phase adjustment unit 103 adjusts the phase of the input carrier signal f ｃ =A ｃ cos(ω ｃ t) by rotating the phase of the carrier signal f ｃ =-A ｃ sin(ω ｃ t) by the phase adjustment unit 103. ｃ =-A ｃ sin(ω ｃt) is distributed by the distributor 106 and input to each multiplier 121 of the odd-term sideband generating unit 112. For example, if the odd-term sideband generating unit 112 includes three multipliers 121, the distributor 106 divides the carrier signal f ｃ =-A ｃ sin(ω ｃ t) to three paths leading to the three multipliers 121. As a result, each multiplier 121 receives a carrier signal f ｃ =-A ｃ sin(ω ｃ t) is input.

[0091] The carrier signal f input to the distribution unit 110 ｃ =A ｃ cos(ω ｃ t) is distributed by the distributor 110 and input to each multiplier 131 of the even-term sideband generating unit 113. For example, if the even-term sideband generating unit 113 includes three multipliers 131, the distributor 110 divides the carrier signal f ｃ =A ｃ cos(ω ｃ t) to three paths leading to the three multipliers 131. As a result, each multiplier 131 receives a carrier signal f ｃ =A ｃ cos(ω ｃ t) is input.

[0092] The signal wave f input to the modulator 10 ｓ = cos(ω ｓ t) is input to the integrator 108. The integrator 108 converts the input signal wave f ｓ = cos(ω ｓ t), the signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ The signal wave f integrated by the integrator 108 is converted into ｓ = (1 / ω ｓ ) sin(ω ｓ t) is input to the energy distribution unit 151.

[0093] The information output unit 150 refers to a power table and acquires power information corresponding to the modulation index β input from the outside. The information output unit 150 outputs the acquired power information to the energy distribution unit 151. The energy distribution unit 151 divides the input signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ t) is weighted in accordance with the power information output from the information output section 150 and output.

[0094] For example, the energy distributor 151 divides the signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ t) is weighted based on the power information corresponding to the first sidebands (±J1) and output from the output port to which the multiplier 120-1 of the odd-term sideband generating unit 112b is connected. The power information corresponding to the first sidebands (±J1) is calculated by the power information of the first sidebands (±J1) shown in P Ｊ１ P, which is indicated by the total power information of all sidebands Ａｌｌ That is, the signal wave f output by the energy distributor 151 to the multiplier 120-1 of the odd-term sideband generator 112b is expressed as ｓ１ is expressed as the following equation (12).

[0095]

[0096] Similarly, the energy distribution unit 151 divides the signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ t) is weighted based on the power information corresponding to the n-th sideband (±Jn) and output from the output port to which the multiplier 120-N of the odd-term sideband generating unit 112b is connected. The power information corresponding to the n-th sideband (±Jn) is expressed as P Ｊｎ P, which is indicated by the total power information of all sidebands Ａｌｌ That is, the signal wave f output by the energy distributor 151 to the multiplier 120-N of the odd-term sideband generator 112b is expressed as ｓｎ is expressed as the following equation (13).

[0097]

[0098] Similarly, the energy distribution unit 151 divides the signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ The power information corresponding to the second sidebands (±J2) is weighted based on the power information corresponding to the second sidebands (±J2) and output from the output port to which the multiplier 130-1 of the even-term sideband generating unit 113b is connected. The power information corresponding to the second sidebands (±J2) is Ｊ２ P, which is indicated by the total power information of all sidebands Ａｌｌ That is, the signal wave f output from the energy distribution unit 151 to the phase adjustment unit 152-1 is expressed as ｓ２ is expressed as the following equation (14).

[0099]

[0100] Similarly, the energy distribution unit 151 divides the signal wave f ｓ = (1 / ω ｓ ) sin(ω ｓ The power information corresponding to the m-th sideband (±Jm) is weighted based on the power information corresponding to the m-th sideband (±Jm) and output from the output port to which the multiplier 130-M of the even-term sideband generating unit 113b is connected. The power information corresponding to the m-th sideband (±Jm) is expressed as P Ｊｍ P, which is indicated by the total power information of all sidebands Ａｌｌ That is, the signal wave f output from the energy distribution unit 151 to the phase adjustment unit 152-M is expressed as ｓｍ is expressed as the following equation (15).

[0101]

[0102] The multiplier 120-1 of the odd-term side wave generating unit 112b multiplies the input signal wave f ｓ１ The multiplier 121-1 multiplies the frequency of the carrier signal f distributed by the distributor 106 by one and outputs the multiplied frequency to the multiplier 121-1 at the subsequent stage. ｃ =-A ｃ sin(ω ｃ t), the signal wave f output from the multiplier 120-1 ｓ１The multiplication unit 121-1 outputs the signal obtained by the multiplication to the multiplexing unit 114. For the sake of simplicity, in the configuration shown in FIG. 2, the output of the multiplication unit 121-1 is expressed as [C １ The signal [C １ ] can be transformed into the following equation (16) based on the product-sum formula: cos(ω ｃ +ω ｓ )t corresponds to the first upper side wave (+J1), and -cos(ω ｃ -ω ｓ )t corresponds to the first lower side wave (-J1).

[0103]

[0104] The multiplier 120-N of the odd-term sideband generating unit 112b multiplies the input signal wave f ｓｎ The frequency of the signal wave f is multiplied by n by the multiplier 120-N and output to the subsequent multiplier 121-N. ｓｎ is expressed as the following equation (17).

[0105]

[0106] The multiplication unit 121-N multiplies the carrier signal f distributed by the distribution unit 106 by ｃ =-A ｃ sin(ω ｃ t), the signal wave f output from the multiplier 120-N ｓｎ The multiplication unit 121-N outputs the signal obtained by the multiplication to the multiplexing unit 114. For the sake of simplicity, in the configuration shown in FIG. 2, the output of the multiplication unit 121-N is expressed as [C ｎ The signal [C ｎ ] can be transformed into the following equation (18) based on the product-sum formula: cos(ω ｃ +nω ｓ )t corresponds to the n-th upper side wave (+Jn), and -cos(ω ｃ -nω ｓ )t corresponds to the nth lower side wave (-Jn).

[0107]

[0108] The phase adjustment unit 152-1 adjusts the phase of the input signal wave f ｓ２ As a result, the phase of the signal wave f input to the phase adjustment unit 152-1 is rotated by 90 degrees. ｓ２ is converted as shown in the following equation (19). ｓ２ is output to the multiplier 130-1 of the even-term sideband generating section 113b.

[0109]

[0110] The phase adjustment unit 152-M adjusts the phase of the input signal wave f ｓｍ As a result, the phase of the signal wave f input to the phase adjustment unit 152-M is rotated by 90 degrees. ｓｍ is converted as shown in the following equation (20). ｓｍ is output to the multiplier 130-M of the even-term sideband generating unit 113b.

[0111]

[0112] The multiplier 130-1 of the even-term sideband generating unit 113b multiplies the input phase-adjusted signal wave f ｓ２ The frequency of the signal wave f is doubled by the multiplier 130-1 and output to the multiplier 131-1 at the subsequent stage. ｓ２ is expressed as the following equation (21).

[0113]

[0114] The multiplier 130-M of the even-term sideband generating unit 113b multiplies the input phase-adjusted signal wave f ｓｍ The frequency of the signal wave f is multiplied by m by the multiplier 130-M and output to the subsequent multiplier 131-M. ｓｍ is expressed as the following equation (22).

[0115]

[0116] The multiplier 131-1 multiplies the carrier signal f distributed by the distributor 110. ｃ =A ｃ cos(ω ｃ t), the signal wave f output from the multiplier 130-1ｓ２ The multiplication unit 131-1 outputs the signal obtained by the multiplication to the multiplexing unit 114. For the sake of simplicity, in the configuration shown in FIG. 2, the output of the multiplication unit 131-1 is expressed as [B ２ The signal [B ２ ] can be transformed into the following equation (23) based on the product-sum formula: cos(ω ｃ +2ω ｓ )t corresponds to the second upper side wave (+J2), and cos(ω ｃ -2ω ｓ )t corresponds to the second lower side wave (-J2).

[0117]

[0118] The multiplication unit 131-M multiplies the carrier signal f distributed by the distribution unit 110. ｃ =A ｃ cos(ω ｃ t), the signal wave f output from the multiplier 130-M ｓｍ The multiplication unit 131-M outputs the signal obtained by the multiplication to the multiplexing unit 114. For the sake of simplicity, in the configuration shown in FIG. 2, the output of the multiplication unit 131-M is expressed as [B ｍ The signal [B ｍ ] can be transformed into the following equation (24) based on the product-sum formula: cos(ω ｃ +mω ｓ ) t corresponds to the m-th upper side wave (+Jm), and cos(ω ｃ -mω ｓ )t corresponds to the mth lower side wave (-Jm).

[0119]

[0120] The modulator 10b converts [A] obtained by the above processing and [B] ２ ]~[B ｍ ] and [C １ ]~[C ｎ] are combined by the combiner 114 to generate an FM signal. That is, the FM signal generated by the modulator 10b is expressed as in the following equation (25). Here, f ＦＭ represents the desired FM waveform (both amplitude, phase and frequency).

[0121]

[0122] The modulator 10b configured as described above includes an energy distributor 151 that distributes the integrated signal wave to be transmitted at a predetermined ratio according to the desired level of each sideband component, an even-term sideband generator 113b that generates one or more signals having even-numbered sideband components based on the carrier signal and the signal wave distributed at the predetermined ratio by the energy distributor 151, and an odd-term sideband generator 112b that generates one or more signals having odd-numbered sideband components based on the carrier signal and the signal wave distributed at the predetermined ratio by the energy distributor 151.

[0123] As a result, the modulator 10b can improve the SNR of the FM waveform more than the configuration of the modulator 10a shown in FIG. 1. Specifically, the modulator 10b can eliminate all of the level adjustment units provided in the odd-term sideband generating unit 112 and the even-term sideband generating unit 113 of the modulator 10a shown in FIG. 1. This simplifies the configuration. Furthermore, since the modulator 10b does not perform correction (amplification) by a level adjustment unit when generating sidebands, it can suppress signal quality degradation caused by amplification of thermal noise. Therefore, it is possible to output an FM waveform with better signal quality (SNR) than the configuration of the modulator 10a shown in FIG. 1.

[0124] (Modification 1 of the embodiment) In the above-described embodiment, the signal wave f ｓ The case where the signal wave f ｓ In this case, a plurality of signal waves f ｓ For example, in the embodiment, the frequency-multiplexed signal may be input to the input terminal of the integrator 108.

[0125] (Modification 2 of the embodiment) In the above-described embodiment, the signal wave f ｓ In the description of the embodiment and the formulas, a cosine signal is used as the input. However, the signal waves to which the present invention is applicable are not limited to cosine signals, and the present invention can also be applied to signal waves of any shape other than cosine.

[0126] (Variation 3 in the embodiment) The integral processing in each of the above-described embodiments (the integral processing described in the text of the specification and in the figures) may be substituted with other processing such as addition, instead of integration, as long as it can produce approximately equivalent mathematical results.

[0127] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0128] The present invention can be applied to an Armstrong modulator that performs frequency modulation.

[0129] 10, 10a, 10b... modulator, 101... carrier signal generating unit, 102, 104, 106, 107, 109, 110, 111... distribution unit, 103, 115... phase adjustment unit, 105, 122-1 to 122-N, 132-1 to 132-M... level adjustment unit, 108... integrator, 112b... odd-term side wave generating unit, 113b... even-term side wave generating unit, 101..., 114... multiplexing unit, 120, 120-1 to 120-N, 130, 130-1 to 130-M... multiplier, 121, 121-1 to 121-N, 131, 131-1 to 131-M... multiplication unit, 123, 133... addition unit 150...information output unit, 151...energy distribution unit, 152-1 to 152-M...phase adjustment units

Claims

1. A modulator comprising: an energy distribution unit that distributes a signal wave to be transmitted after integration or an operation approximately equivalent to integration at a predetermined ratio according to the desired level of each sideband component; an even-term sideband generation unit that generates one or more signals having even-numbered sideband components based on a carrier signal and the signal wave distributed at the predetermined ratio by the energy distribution unit; and an odd-term sideband generation unit that generates one or more signals having odd-numbered sideband components based on the carrier signal and the signal wave distributed at the predetermined ratio by the energy distribution unit.

2. The modulator according to claim 1, wherein the energy distribution section determines a predetermined ratio according to a desired level for each sideband component based on a modulation index during frequency modulation.

3. The modulator according to claim 2, further comprising an information output unit that outputs information to the energy distribution unit by referring to a power table in which power information of each sideband component according to a modulation index during said frequency modulation is associated with information on the total value of the power of all sidebands, and the energy distribution unit determines a distribution ratio for each sideband component based on the information output from the information output unit.

4. A modulator as claimed in any one of claims 1 to 3, wherein the energy distribution unit increases the ratio so that the energy of a sideband component having a large amplitude value or power value is increased, and decreases the ratio so that the energy of a sideband component having a small amplitude value or power value is decreased.

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