JP2014036388A - Transmitter, program, and storage medium thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately control a transmission output in a transmitter that executes transmission processing by selecting a modulation system used for transmission processing from a plurality of modulation systems.SOLUTION: Feedback control is performed only when a power level of a transmission signal is not less than a threshold value, and the threshold value for determining whether or not feedback control should be executed is changed according to a modulation system used for transmission processing.

Description

  The present invention relates to a transmission apparatus that performs transmission processing by selecting a modulation scheme to be used for transmission processing from among a plurality of modulation schemes.

  Conventionally, in a transmission device such as a mobile phone, in order to ensure the linearity of the transmission output, feedback control for detecting the output power of the power amplifier with a detector and controlling the transmission output based on the detection result has been performed. Yes.

  For example, in Patent Document 1, an output of a power amplifier detected by a detector is input to an inverting terminal of a comparator via a first variable attenuator, and an input to the power amplifier is input via a second variable attenuator. And the output of the comparator is input to the power control terminal of the power amplifier, and the attenuation amount of the first and second variable attenuators is controlled by controlling the attenuation amount of the power amplifier. A technique for performing power control is disclosed.

Japanese Unexamined Patent Publication No. 4-130805 (published on May 1, 1992)

  By the way, the error range of the transmission output (output power) required for the transmission apparatus is defined for each modulation method by a standard established by 3GGP (3rd Generation Partnership Project), and the error characteristic of the transmission output is also determined by the modulation method. Every one is different.

  However, in a conventional transmission apparatus that performs transmission processing by selecting a modulation method to be used for transmission processing from among a plurality of modulation methods, switching of detector ON / OFF (switching of presence or absence of feedback control) depends on the modulation method. It is based on a uniquely set threshold.

  For this reason, in the conventional technique, the linearity of the transmission output cannot be ensured depending on the modulation method used for the transmission process, and the error of the transmission output may exceed the error range required for the modulation method.

  The present invention has been made in view of the above problems, and an object of the present invention is to appropriately transmit output in a transmission apparatus that performs transmission processing by selecting a modulation method to be used for transmission processing from a plurality of modulation methods. There is to control.

  The transmission apparatus of the present invention is a transmission apparatus that can select a modulation scheme used for transmission processing from a plurality of modulation schemes, a signal generation unit that generates a transmission signal of the selected modulation scheme, and the transmission signal An amplifying unit for amplifying, a detection unit for detecting a power level of the transmission signal amplified by the amplifying unit, at least one of a power level of the transmission signal generated by the signal generating unit and a gain of the amplifying unit, A modulation control unit that performs feedback control based on the detection result of the detection unit such that the power level of the transmission signal amplified by the amplification unit approaches the target power level, and the modulation control unit includes the target power level. Or, when the predetermined power level of the power level detected by the detection unit is equal to or higher than the threshold value, the feedback control is performed, but less than the threshold value. Without the feedback control in the case, and is characterized in that to change according to the modulation scheme used for transmission processing said threshold.

  According to the above configuration, the modulation control unit determines whether to feedback control at least one of the power level of the transmission signal generated by the signal generation unit and the gain of the amplification unit based on the detection result of the detection unit. Therefore, the power level threshold value is changed for each modulation method used for transmission processing. As a result, the transmission output can be appropriately controlled for each modulation method.

  The signal generation unit includes a modulation unit that modulates a baseband signal into a transmission signal of a selected modulation method, and an attenuation processing unit that performs attenuation processing on the power level of the transmission signal modulated by the modulation unit. The modulation control unit may be configured to feedback control the attenuation amount of the power level of the transmission signal in the attenuation process based on the detection result of the detection unit.

  According to the above configuration, the transmission output can be appropriately controlled by feedback control of the power level of the transmission signal.

  The modulation control unit feedback-controls both an attenuation amount of a power level of a transmission signal in the attenuation process and a gain of the amplification unit based on a detection result of the detection unit. The transmitting device according to 1.

  Alternatively, a modulation scheme used for transmission processing may be selected according to an instruction from an external device or a communication state with the external device.

  According to the above configuration, the modulation method used for the transmission process is selected according to the instruction from the external device or the communication state with the external device, and the transmission process is performed with an appropriate transmission output according to the selected modulation method. Can do.

  The transmission device may be realized by a computer. In this case, a program that causes the transmission device to be realized by the computer by operating the computer as the modulation control unit, and a computer reading that records the program. Possible recording media are also included in the scope of the present invention.

  As described above, according to the transmission apparatus of the present invention, the transmission output can be appropriately controlled for each modulation scheme.

It is explanatory drawing which shows schematic structure of the communication terminal device (transmission device) concerning one Embodiment of this invention. It is explanatory drawing which shows schematic structure of RFIC with which the communication terminal device shown in FIG. 1 is equipped. It is a graph which shows the correlation with the transmission output about two types of modulation waves, and the detection voltage of a detector. It is explanatory drawing which shows an example of the threshold value table memorize | stored in the threshold value table memory | storage part with which the communication terminal device shown in FIG. 1 is equipped. It is a flowchart which shows the flow of a process in RFIC with which the communication terminal device shown in FIG. 1 is equipped. It is explanatory drawing which shows the other example of the threshold value table memorize | stored in the threshold value table memory | storage part with which the communication terminal device shown in FIG. 1 is equipped.

  An embodiment of the present invention will be described.

(1-1. Configuration of Communication Terminal Device 10)
FIG. 1 is an explanatory diagram showing a schematic configuration of a communication terminal device (transmission device) 10 according to the present embodiment. As shown in this figure, the communication terminal apparatus 10 includes a main control unit 11, a transmission unit 12, a reception unit 13, a storage unit 14, an operation unit 15, a display unit 16, a voice input unit 17, and a voice output unit 18. ing. The communication terminal device 10 may be any communication device having at least a transmission function. For example, the communication terminal device 10 may be a mobile phone, a smartphone, a tablet terminal, a PDA (Personal Digital Assistance), a notebook computer, a portable game. It may be a machine.

  The main control unit 11 is a computer device that includes an arithmetic processing unit such as a CPU or a dedicated processor, and a storage unit (not shown) such as a RAM or a ROM, and is stored in the storage unit. The operation of each part of the communication terminal device 10 is controlled by reading and executing various information and programs for performing various controls.

  The transmission unit (transmission device) 12 transmits various data (for example, voice data, image data, text data, etc.) to an external device (for example, a base station) in response to an instruction from the main control unit 11. Details of the transmission unit 12 will be described later.

  The receiving unit 13 receives various data transmitted from an external device.

  The storage unit 14 stores various data according to instructions from the main control unit 11. For example, the storage unit 14 stores data received from the external device by the receiving unit 13, data input by the user via the operation unit 15, audio data input by the user via the audio input unit 17, and the like. The main control unit 11 reads various data stored in the storage unit 14 as necessary, transmits the data to the external device via the transmission unit 12, displays the data on the display unit 16, and displays the audio output unit 18. Sound output. Note that the software executed in the main control unit 11 may be stored in the storage unit 14.

  The operation unit 15 receives an instruction input from the user and transmits it to the main control unit 11. For example, various key buttons can be used as the operation unit 15.

  The display unit 16 displays information to be presented to the user in response to an instruction from the main control unit 11. As the display unit 16, for example, a liquid crystal display panel or an organic EL display can be used. A touch panel having both the function of the display unit 16 and the function of the operation unit 15 may be used.

  The voice input unit 17 acquires voice data of sounds uttered by the user and surrounding sounds. The audio output unit 18 reproduces and outputs audio data stored in the storage unit 14 and audio data received from an external device.

(1-2, Configuration of Transmitter 12)
As shown in FIG. 1, the transmission unit 12 includes a BBIC (baseband IC) 21, an RFIC (high frequency IC, signal generation unit) 22, an amplifier (power amplifier, amplification unit) 23, an isolator 24, and a coupler (coupler). 25, a duplexer 26, an antenna 27, and a detector (detector, detector) 28.

  The BBIC 21 generates a baseband signal (I / Q signal) of transmission data to be transmitted to an external device in accordance with an instruction from the main control unit 11 and outputs it to the RFIC 22. Note that the baseband signal is typically a low-frequency signal such as 1 MHz.

  The RFIC 22 converts the baseband signal input from the BBIC 21 into an RF signal (high frequency signal, transmission signal) and outputs it to the amplifier 23. For example, the RFIC 22 converts the baseband signal input from the BBIC 21 into a 2 GHz high-frequency signal adopted in the WCDMA (Wideband Code Division Multiple Access) standard, the HSDPA (High-Speed Downlink Packet Access) standard, or the like. Details of the RFIC 22 will be described later.

  The amplifier 23 amplifies the power (power level) of the RF signal input from the RFIC 22 and outputs it to the isolator 24.

  The isolator 24 is a member for stabilizing the load of the amplifier 23, and is a kind of filter having a characteristic that the loss in the forward direction is small and the loss in the reverse direction is very large.

  The coupler 25 branches the transmission wave and outputs it to the detector 28 and the duplexer 26.

  The duplexer 26 separates the transmission wave input from the coupler 25 and the reception wave received by the antenna 27, outputs the transmission wave to the antenna 27, and outputs the reception wave to the reception unit 13.

  The antenna 27 is for receiving a radio wave transmitted from the external device to the communication terminal device 10 and transmitting a radio wave transmitted from the communication terminal device 10 to the external device.

  The detector 28 detects the power (power level) of the transmission wave amplified by the amplifier 23 based on the transmission wave input through the coupler 25, and outputs a detection signal having a voltage value corresponding to the detection result to the RFIC 22. Output. In the RFIC 22, the attenuation amount of the RF signal is controlled in accordance with the detection signal fed back through the detector 28.

(1-3. Configuration of RFIC 22)
FIG. 2 is an explanatory diagram showing a schematic configuration of the RFIC 22. As shown in this figure, the RFIC 22 includes a modulation unit 31, a variable attenuator (attenuation processing unit) 32, a modulation control unit 33, a threshold table storage unit 34, and an attenuation amount calculation data storage unit 35.

  The modulation unit 31 modulates the baseband signal input from the BBIC 21 into an RF signal and outputs the RF signal to the variable attenuator 32.

  In the present embodiment, the modulation unit 31 uses a QPSK modulation type modulation wave specified by the R99 (Release 99) standard or a 16QAM modulation type modulation wave specified by the HSDPA standard as the baseband signal. It converts it to the RF signal that was received.

  The variable attenuator 32 attenuates the RF signal input from the modulation unit 31 according to an instruction from the modulation control unit 33 and outputs the attenuated signal to the amplifier 23.

  The modulation control unit 33 determines whether the main control unit 11 converts the modulation wave corresponding to the R99 standard (QPSK modulation type modulation wave) or the HSDPA standard modulation wave (16QAM modulation type modulation wave). Modulation scheme instruction information and transmission output instruction information indicating transmission output (target output level) are input. Note that the main control unit 11 uses, for example, an instruction received from an external device (eg, a TPC command received from a base station) or a modulation scheme instruction information and transmission output based on a communication state between the communication terminal device 10 and the external device. Generate instruction information. The means for detecting the communication state between the communication terminal device 10 and the external device may be provided in the communication terminal device 10 or in the external device.

  The modulation control unit 33 converts the baseband signal input to the modulation unit 31 into output power corresponding to the transmission output instruction information input from the main control unit 11 and a modulation wave of the modulation method specified by the modulation method instruction information. The operation of the modulation unit 31 is controlled so as to be modulated. The modulation control unit 33 is not limited to the configuration provided in the RFIC 22, and may be provided as a part of the main control unit 11, for example.

  Further, the modulation control unit 33 feedback-controls the attenuation amount of the RF signal based on the modulation method instruction information and transmission output instruction information input from the main control unit 11 and the detection signal input from the detector 28. Judgment is necessary. Further, when performing feedback control, the modulation control unit 33 calculates the attenuation amount of the RF signal based on the transmission output instruction information input from the main control unit 11 and the detection signal input from the detector 28. An instruction is sent to the variable attenuator 32 to attenuate the RF signal by the amount of attenuation.

  The threshold value table storage unit 34 stores a threshold value table in which a transmission output threshold value for determining whether or not to perform feedback control is set for each modulation method.

  FIG. 3 is a graph showing the correlation between the transmission output (dBm) and the detection voltage (V) of the detector 28 for each modulation method. As shown in this figure, the modulation system corresponding to the R99 standard shows a substantially linear (substantially proportional) correlation between the transmission output and the detection voltage over a relatively wide range, but in the modulation system corresponding to the HSDPA standard, A nonlinear correlation is shown in a region where the value of the transmission output (dBm) is relatively small. That is, in the modulation scheme corresponding to the HSDPA standard, an error between the transmission output and the detection power of the detector 28 increases in a region where the value of the transmission output (dBm) is relatively small.

  For this reason, when a modulation scheme corresponding to the HSDPA standard is used, if the feedback control is performed in a region where the value of the transmission output (dBm) is relatively small, the error of the transmission output is enlarged, and the linearity of the transmission output is increased. It may not be possible to secure the sex.

  Therefore, in this embodiment, the modulation control unit 33 sets the attenuation amount in the variable attenuator 32 to zero without performing feedback control when the power (target power level) corresponding to the transmission output instruction information is less than the threshold value. The setting is made, and the above-described threshold is made different for each modulation method.

  FIG. 4 is an explanatory diagram illustrating an example of the threshold value table stored in the threshold value table storage unit 34. In the example shown in this figure, in the case of the modulation method corresponding to the R99 standard, when the transmission output is 1 dBm (threshold A) or more, feedback control (control for changing the attenuation in the variable attenuator 32 according to the detection signal). Is set so that feedback control is not performed when it is less than 1 dBm. Further, in the case of a modulation method corresponding to the HSDPA standard, the feedback control is performed when the transmission output is 4 dBm (threshold B) or more, and the feedback control is not performed when the transmission output is less than 4 dBm.

  The attenuation amount calculation data storage unit 35 stores data indicating the relationship between the detection voltage of the detector 28 and the transmission output corresponding to the detection voltage (for example, a table or an arithmetic expression in which the detection voltage and the transmission output are associated with each other). doing. That is, in the attenuation amount calculation data storage unit 35, for example, the transmission output corresponding to the detection voltage is specified such that the transmission output in the case of the detection voltage 800 mV is 20 dBm, and the transmission output in the case of the detection voltage 700 mV is 15 dBm. Is stored.

  The modulation control unit 33 calculates the transmission output of the RF signal amplified by the amplifier 23 based on the data stored in the attenuation calculation data storage unit 35 and the detection signal input from the detector 28. Further, the modulation control unit 33 calculates the difference between the calculated transmission output and the target transmission output corresponding to the transmission output instruction information from the main control unit 11, and sets the attenuation amount of the RF signal for realizing the target transmission output. calculate. Then, the modulation control unit 33 controls the operation of the variable attenuator 32 so as to realize the attenuation amount calculated as described above.

(1-4. Operation during modulation processing)
FIG. 5 is a flowchart showing the flow of processing in the RFIC 22.

  When the modulation control unit 33 receives a transmission processing start instruction from the main control unit 11 (S1), the modulation method used based on the modulation method instruction information input from the main control unit 11 is modulated corresponding to the R99 standard. It is determined whether to use a modulation method or a modulation method corresponding to the HSDPA standard (S2).

  When it is determined in S2 that the modulation method corresponding to the R99 standard is used, the modulation control unit 33 controls the modulation unit 31 to modulate the baseband signal input from the BBIC 21 to the modulation unit 31 in accordance with the R99 standard. Modulation is made into a system RF signal (S3). Further, the modulation control unit 33 is based on the threshold value table stored in the threshold value table storage unit 34, and the transmission output (target output level) corresponding to the transmission output instruction information from the main control unit 11 is the R99 standard modulation method. It is determined whether or not the threshold value A is equal to or greater than the threshold value A (S4).

  On the other hand, when it is determined in S2 that the modulation method corresponding to the R99 standard is not used (when it is determined that the modulation method corresponding to the HSDPA standard is used), the modulation control unit 33 controls the modulation unit 31 to perform modulation from the BBIC 21. The baseband signal input to the unit 31 is modulated into an RF signal of a modulation system corresponding to the HSDPA standard (S5). Further, the modulation control unit 33 has a transmission output (target output level) corresponding to the transmission output instruction information from the main control unit 11 based on the threshold value table stored in the threshold value table storage unit 34. It is determined whether or not the threshold value B is equal to or greater than the threshold value B corresponding to (S6).

  When it is determined that the transmission output is greater than or equal to the threshold A in S4 and when it is determined that the transmission output is greater than or equal to the threshold B in S6, the modulation control unit 33 controls the variable attenuator 32 to The amount of attenuation is controlled (feedback control) (S7). That is, the modulation control unit 33 sets the transmission output to the target transmission output that is the transmission output corresponding to the transmission output instruction information from the main control unit 11 based on the detection signal input from the detector 28 (or The attenuation amount of the RF signal (to be close to the target transmission output) is calculated, and the operation of the variable attenuator 32 is controlled so as to realize the calculated attenuation amount.

  When it is determined in S4 that the transmission output is less than the threshold A, when it is determined in S6 that the transmission output is less than the threshold B, and when the attenuation amount of the RF signal is controlled in S7, the modulation control unit 33 Then, it is determined whether or not to end the transmission process (S8). If not, the process returns to S1 and the transmission process is continued.

(1-5. Effects of Communication Terminal Device 10)
As described above, the communication terminal device 10 according to the present embodiment stores a threshold table in which the threshold value of the transmission output for determining whether or not to perform feedback control of the transmission output is set for each modulation scheme to be used. Whether or not to perform feedback control of the transmission output is determined based on the threshold value corresponding to the modulation method to be used and the transmission output corresponding to the detection result of the detector 28. Note that, in a region where the transmission output is small, in general, amplification processing in the amplifier 23 is not performed, or even if amplification processing is performed, the gain is small. Therefore, even if feedback control is not performed, amplification is performed by the amplifier. The deviation between the transmission output and the target transmission output is relatively small, and the linearity of the transmission output can be maintained.

  Therefore, according to this embodiment, it is possible to appropriately control the transmission output for each modulation scheme. That is, even when the error between the detection result of the detector 28 and the target transmission output increases according to the modulation scheme, the transmission output can be appropriately controlled for each modulation scheme, and the linearity of the transmission output can be reduced. Can be improved. Thus, for example, even if the transmission method is selectively switched between the modulation method corresponding to the R99 standard and the modulation method corresponding to the HSDPA standard, the 3GPP (3rd Generation Partnership Project) established It is possible to satisfy the conditions of transmission output error required for each of these standards.

(1-6. Modification of Communication Terminal Device 10)
In this embodiment, the configuration in which the modulation scheme used for the transmission process is selected from the modulation scheme corresponding to the R99 standard or the modulation scheme corresponding to the HSDPA standard has been described. However, the modulation used for the transmission processing is selected from a plurality of modulation schemes. Any configuration may be used as long as transmission processing is performed by selecting a method, and the combinations of modulation methods that can be selected are not limited thereto. For example, instead of one or both of the modulation method corresponding to the R99 standard or the modulation method corresponding to the HSDPA standard, or in addition to the modulation method corresponding to the R99 standard and the modulation method corresponding to the HSDPA standard, another modulation method is selected. It may be possible.

  FIG. 6 is used for transmission processing from among three modulation schemes: a modulation scheme corresponding to the R99 standard, a modulation scheme corresponding to the HSDPA standard, and a modulation scheme corresponding to the LTE (Long Term Evolution) standard (64QAM modulation scheme). It is explanatory drawing which shows an example of the threshold value table in the case of selecting a modulated wave. In the example shown in this figure, in the case of the modulation method b corresponding to the R99 standard, when the transmission output is 1 dBm (threshold A) or more, feedback control (control for changing the attenuation in the variable attenuator 32 according to the detection signal). Is set so that the feedback control is not performed when it is less than 1 dBm. Further, in the case of a modulation method corresponding to the HSDPA standard, the feedback control is performed when the transmission output is 4 dBm (threshold B) or more, and the feedback control is not performed when the transmission output is less than 4 dBm. Further, in the case of a modulation system corresponding to the LTE standard, the feedback control is performed when the transmission output is 20 dBm (threshold C) or more, and the feedback control is not performed when the transmission output is less than 20 dBm.

  Further, the values of the thresholds A to C set for each modulation method in the present embodiment are merely examples, and the present invention is not limited to these values. For example, the detection characteristics of the detector 28 and the modulation methods. It may be changed as appropriate in consideration of the characteristics and standards.

  In this embodiment, the necessity of feedback control is determined based on the comparison result between the transmission output (target output level) corresponding to the transmission output instruction information from the main control unit 11 and the threshold value stored in the threshold value table. However, it is not limited to this. For example, the necessity of feedback control may be determined based on the comparison result between the transmission output (output level) detected by the detector 28 and the threshold value stored in the threshold value table.

  In the present embodiment, the configuration in which the attenuation amount of the RF signal before being input to the amplifier 23 generated by the RFIC 22 is controlled (feedback control) based on the transmission output detected by the detector 28 has been described. For example, the gain of the amplifier 23 may be controlled (feedback control) based on the transmission output detected by the detector 28. However, when feedback control is performed on the attenuation amount of the RF signal before being input to the amplifier 23, (i) when an amplifier with a constant gain is used as the amplifier 23 or an amplifier with low gain control accuracy is used. Even if it exists, the effect that a transmission output can be controlled appropriately and the especially advantageous effect that a transmission output can be controlled more accurately than the case where (ii) the gain of the amplifier 23 is feedback-controlled are acquired.

  Further, both the attenuation amount of the RF signal before being input to the amplifier 23 and the gain of the amplifier 23 may be controlled (feedback control) based on the transmission output detected by the detector 28.

(1-7. Example of program)
In the present embodiment, the main control unit 11 and / or the modulation control unit 33 of the communication terminal device 10 may be realized in hardware by a logic circuit formed on an integrated circuit (IC chip), or a CPU ( It may be realized by software using a Central Processing Unit.

  In the latter case, the communication terminal device 10 includes a CPU that executes instructions of a program that realizes each function, a ROM (Read Only Memory) that stores the program, a RAM (Random Access Memory) that expands the program, the program, A storage device (recording medium) such as a memory for storing various data is provided. An object of the present invention is a recording medium on which a program code (execution format program, intermediate code program, source program) of a control program of the communication terminal device 10 which is software for realizing the above-described functions is recorded so as to be readable by a computer This can also be achieved by supplying the communication terminal device 10 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include non-transitory tangible medium, such as magnetic tape and cassette tape, magnetic disk such as floppy (registered trademark) disk / hard disk, and CD-ROM / MO. Discs including optical discs such as / MD / DVD / CD-R, cards such as IC cards (including memory cards) / optical cards, semiconductor memories such as mask ROM / EPROM / EEPROM (registered trademark) / flash ROM Alternatively, logic circuits such as PLD (Programmable Logic Device) and FPGA (Field Programmable Gate Array) can be used.

  The communication terminal device 10 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited as long as it can transmit the program code. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication network, and the like can be used. The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, even with wired lines such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA and remote control, Bluetooth (registered trademark), IEEE 802.11 wireless, HDR ( It can also be used by radio such as High Data Rate (NFC), Near Field Communication (NFC), Digital Living Network Alliance (DLNA), mobile phone network, satellite line, and digital terrestrial network. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be applied to a transmission apparatus that performs transmission processing by selecting a modulation scheme to be used for transmission processing from among a plurality of modulation schemes.

10 Communication terminal device (transmission device)
11 Main Control Unit 12 Transmitter (Transmitter)
21 BBIC
22 RFIC (signal generator)
23 Amplifier (amplifier)
24 Isolator 25 Coupler 26 Demultiplexer 27 Antenna 28 Detector (Detector)
31 Modulator 32 Variable Attenuator (Attenuation Processing Unit)
33 Modulation control unit 34 Threshold table storage unit 35 Attenuation amount calculation data storage unit

Claims (6)

A transmission device capable of selecting a modulation method used for transmission processing from a plurality of modulation methods,
A signal generation unit for generating a transmission signal of the selected modulation method;
An amplifier for amplifying the transmission signal;
A detection unit for detecting a power level of the transmission signal amplified by the amplification unit;
At least one of the power level of the transmission signal generated by the signal generation unit and the gain of the amplification unit is detected by the detection unit so that the power level of the transmission signal amplified by the amplification unit approaches a target power level. A modulation control unit that performs feedback control based on the result,
The modulation control unit
The feedback control is performed when the predetermined power level of the target power level or the power level detected by the detection unit is greater than or equal to a threshold value, while the feedback control is not performed when the power level is less than the threshold value, and A transmission apparatus characterized in that the threshold value is changed according to a modulation method used for transmission processing. The signal generator is
A modulator that modulates a baseband signal into a transmission signal of a selected modulation method;
An attenuation processing unit that performs attenuation processing of the power level of the transmission signal modulated by the modulation unit,
The modulation control unit
The transmission apparatus according to claim 1, wherein feedback control is performed on an attenuation amount of a power level of the transmission signal in the attenuation process based on a detection result of the detection unit. The modulation control unit
The transmission apparatus according to claim 2, wherein both the attenuation amount of the power level of the transmission signal in the attenuation process and the gain of the amplification unit are feedback-controlled based on the detection result of the detection unit.   The transmission apparatus according to any one of claims 1 to 3, wherein a modulation method used for transmission processing is selected according to an instruction from an external apparatus or a communication state with the external apparatus.   A program for operating the transmission device according to claim 1, wherein the program causes a computer to function as the modulation control unit. A computer-readable recording medium on which the program according to claim 5 is recorded.

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