Electromagnetic wave transmission device

Abstract

To provide an electromagnetic wave transmitting device and an electromagnetic wave communication system that increase the transmission speed. [Solution] In the electromagnetic wave communication system 10, the electromagnetic wave transmitting device 20 includes a transmitting unit 28 that transmits electromagnetic waves indicating a modulated signal, having a maximum value and a minimum value located on the voltage side higher than the maximum value in its voltage-current characteristics; an acquisition unit 22 that acquires a digital signal; and a modulation unit (conversion unit 24) that modulates the digital signal into a modulated signal using at least one of a first voltage value at two or more levels in a first voltage region which is a voltage region above the maximum value and below the minimum value, a second voltage value in a second voltage region which is a voltage region below the maximum value, and a third voltage value in a third voltage region which is a voltage region on the voltage side higher than the minimum value.

Description

[Technical Field]

[0001] This invention relates to an electromagnetic wave transmitting device and an electromagnetic wave communication system. [Background technology]

[0002] Amplitude-shift keying (ASK modulation) is a known modulation scheme used for communication in oscillators for electromagnetic wave transmission. On-off keying (OOK modulation) is also known as one of the ASK modulation schemes.

[0003] Here, Patent Document 1 discloses a technology relating to an ASK modulation scheme that uses a resonant tunneling diode (RTD) as an oscillator for electromagnetic wave transmission. Specifically, this technology represents binary values ​​by switching between data in the oscillation region of the RTD (for example, a signal corresponding to On) and data in the non-oscillating region (for example, a signal corresponding to Off), that is, a technology that represents On and Off by the difference in amplitude. Furthermore, Patent Document 2 discloses a technology related to an ASK modulation scheme using continuous-oscillating terahertz waves such as RTDs. Specifically, this technology involves superimposing variable light of variable intensity as signal light onto a modulation element and modulating the amplitude of the terahertz wave according to the signal intensity. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2012-191520 [Patent Document 2] Japanese Patent Publication No. 2010-41204 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the technologies disclosed in Patent Documents 1 and 2 are based on representing binary values ​​by differences in amplitude, which limits the ability to increase the transmission speed (or communication speed).

[0006] One example of a problem that this invention aims to solve is increasing the transmission speed. [Means for solving the problem]

[0007] The invention described in claim 1 is, A transmitting unit that transmits electromagnetic waves indicating a modulated signal, wherein the voltage-current characteristics have a maximum value and a minimum value located on the voltage side higher than the maximum value, An acquisition unit that acquires digital signals, A modulation unit modulates the aforementioned digital signal using at least one of two first voltage values ​​in a first voltage region defined as a voltage range greater than or equal to the maximum voltage and less than or equal to the minimum voltage, a second voltage value in a second voltage region defined as a voltage range less than the maximum voltage, and a third voltage value in a third voltage region defined as a voltage range higher than the minimum voltage, and modulates the aforementioned modulated signal. It is an electromagnetic wave transmitting device equipped with [a specific feature]. [Brief explanation of the drawing]

[0008] The aforementioned objectives, as well as other objectives, features, and advantages, will become even clearer from the preferred embodiments described below and the accompanying drawings.

[0009] [Figure 1] This is a schematic diagram of the electromagnetic wave communication system of this embodiment. [Figure 2] This is a schematic diagram of the electromagnetic wave transmitting device included in the electromagnetic wave communication system of this embodiment. [Figure 3] This graph shows the voltage-current characteristics of the electromagnetic wave oscillating element in the electromagnetic wave transmitting device of this embodiment, as well as the voltage values ​​at three levels within the oscillation region. [Figure 4]This is an example of the modulation signal transmitted by the electromagnetic wave transmission device of the present embodiment. [Figure 5] This is another example of the modulation signal transmitted by the electromagnetic wave transmission device of the present embodiment.

Embodiment for Carrying Out the Invention

[0010] <Overview> Hereinafter, the present embodiment (an example of the present invention) will be described. First, the functions and configuration of the electromagnetic wave communication system 10 (see FIG. 1) of the present embodiment will be described with reference to the drawings. Next, the operation of the electromagnetic wave communication system 10 of the present embodiment will be described with reference to the drawings. The effects of the present embodiment will be described in the description of the operation. In all the drawings to be referred to, components having the same functions are denoted by the same reference numerals, and the description will be appropriately omitted in the specification.

[0011] <Configuration> FIG. 1 is a schematic diagram of the electromagnetic wave communication system 10 of the present embodiment. The electromagnetic wave communication system 10 includes an electromagnetic wave transmission device 20 and an electromagnetic wave reception device 30. The electromagnetic wave communication system 10 has a function of receiving the electromagnetic wave W transmitted by the electromagnetic wave transmission device 20 by the electromagnetic wave reception device 30. <http: / / www.example.com / <http: / / www.example.com /

[0012] <http: / / www.example.com / The electromagnetic wave W of the present embodiment is an electromagnetic wave indicating a modulation signal to be described later. Further, the electromagnetic wave W of the present embodiment is, as an example, a terahertz wave. Here, the terahertz wave is said to be an electromagnetic wave having a shorter wavelength than the millimeter wave and a longer wavelength than the infrared ray. The terahertz wave is an electromagnetic wave having both the properties of light waves and radio waves. For example, it has the property of passing through (or easily passing through) cloth, paper, wood, plastic, ceramics, etc., and not passing through (or hardly passing through) metals, water, etc. Generally, the frequency of the terahertz wave is also said to be an electromagnetic wave around 1 THz (the wavelength corresponds to around 300 μm), but there is no generally clear definition for that range. Therefore, in this specification, the wavelength range of the terahertz wave is defined as a range of 70 GHz or more and 10 THz or less.

[0013] 〔Electromagnetic Wave Transmission Device〕 Figure 2 is a schematic diagram of the electromagnetic wave transmitting device 20 of this embodiment. The electromagnetic wave transmitting device 20 has the function of transmitting an electromagnetic wave W that represents a multi-level modulated signal. The electromagnetic wave transmitting device 20 includes, as an example, an acquisition unit 22, a conversion unit 24 (an example of a modulation unit), a switching unit 26A, a selector 26B, a transmission unit 28, a multi-level setting unit 29A, and a synchronization level setting unit 29B.

[0014] (Acquisition Department) In this embodiment, the acquisition unit 22 has the function of acquiring digital signals such as sound and video. The acquisition unit 22 also has the function of outputting the acquired digital signals to the conversion unit 24.

[0015] (Conversion section) The conversion unit 24 of this embodiment includes, as an example, a multi-level conversion unit 24A and a synchronization signal level conversion unit 24B. The multi-level conversion unit 24A takes a digital signal (communication data) from the acquisition unit 22 as input and has the function of converting it to a multi-level according to the multi-level setting and outputting it. Here, the multi-level setting means setting two or more voltage levels (first voltage values ​​V2, V3, V4) in the first voltage region RA described later, as well as setting at least one of the voltage levels of the second voltage region RB described later (second voltage value V1) and the voltage value level of the third voltage region described later (third voltage value V5) (see Figure 3). Furthermore, the synchronization signal level conversion unit 24B has the function of outputting a predetermined synchronization signal level according to the synchronization level setting. Here, the synchronization level setting means setting two or more voltage levels in the first voltage region RA, and at least one of the voltage levels of the second voltage region RB and the voltage value level of the third voltage region (see Figure 3).

[0016] (Switching section and selection section) The switching unit 26A has the function of generating the switching timing for the data selected by the selector 26B and output to the transmission unit 28, and inputting it to the selector 26B. Here, the data refers to the data output by the multi-level conversion unit 24A (hereinafter referred to as multi-level data) and the data output by the synchronization signal level conversion unit 24B (hereinafter referred to as synchronization signal data). The selector 26B has the function of outputting synchronization signal data and multi-level data to the transmission unit 28 at different timings, according to the switching timing of the data generated by the switching unit 26A.

[0017] (Transmitter) The transmitter 28 has the function of oscillating the data selected and input by the selector 26B as an electromagnetic wave W (in this embodiment, a terahertz wave as described above). Therefore, the transmitter 28 has an element that oscillates terahertz waves. In this embodiment, the element that oscillates terahertz waves is, for example, an RTD. However, any element that oscillates terahertz waves does not have to be an RTD.

[0018] Here, the voltage-current characteristics of the RTD (the characteristics of current relative to voltage in a two-dimensional graph showing the relationship between voltage and current) will be explained with reference to the graph in Figure 3. Figure 3 is a graph showing the voltage-current characteristics of the RTD of this embodiment, as well as the first voltage values ​​V2, V3, and V4 at three levels within the first voltage region RA, the second voltage value V1 in the second voltage region RB, and the third voltage value V5 in the third voltage region RC. The RTD has a maximum value and a minimum value located at a higher voltage than the maximum value in its voltage-current characteristics. Here, the voltage value at the maximum value is the voltage value V. OL Let the voltage value at the minimum be the voltage value V. OH This is defined as follows. And the voltage value V OL From the voltage value V OHThe current spectrum over this range is considered to be a differential negative resistance region exhibiting differential negative resistance characteristics. In this specification, this differential negative resistance region is defined as the first voltage region RA. That is, the RTD has a differential negative resistance region (first voltage region RA) exhibiting differential negative resistance characteristics in the voltage-current characteristics of its operating region. Furthermore, in this specification, among the voltage regions on both sides of the first voltage region RA in the voltage-current characteristic graph, the voltage value V OL The region with a lower voltage is called the second voltage region RB, and the voltage value V OH The region with a higher voltage than this is defined as the third voltage region RC. The RTD functions as an element that emits electromagnetic waves W when at least one of the first voltage values ​​V2, V3, and V4 in the first voltage region RA, the second voltage value V1 in the second voltage region RB, and the third voltage value V5 in the third voltage region is applied.

[0019] When the transmission unit 28 receives synchronization signal data from the synchronization signal level conversion unit 24B, it transmits a synchronization signal having a pattern corresponding to at least one of the voltage values ​​of the three levels of first voltage values ​​V2, V3, and V4 in the first voltage region RA, the second voltage value V1 in the second voltage region RB, and the third voltage value V5 in the third voltage region. In this embodiment, the synchronization signal is a signal that informs the electromagnetic wave receiving device 30 of the detection timing of the transmitted signal, and also plays a role in allowing it to recognize some or all of the voltage levels used in the modulation signal. Subsequently, when the transmission unit 28 receives multi-level data from the multi-level conversion unit 24A, it transmits a digital signal having a pattern corresponding to at least one of the voltage values ​​of the three levels of first voltage values ​​V2, V3, and V4 in the first voltage region RA, the second voltage value V1 in the second voltage region RB, and the third voltage value V5 in the third voltage region. In this embodiment, the first voltage values ​​V2, V3, and V4 within the first voltage region RA are taken as three voltage levels as an example, but it is sufficient for the first voltage values ​​within the first voltage region RA to be two or more levels.

[0020] As described above, the multi-level setting and synchronization level setting in this embodiment are set to at least one of the voltage values ​​of the three levels of first voltage values ​​V2, V3, and V4 in the first voltage region RA, the second voltage value V1 in the second voltage region RB, and the third voltage value V5 in the third voltage region. Furthermore, the electromagnetic wave transmitter 20 in this embodiment modulates the multi-level data and synchronization signal data with multi-level modulation and transmits the multi-level modulated data to the electromagnetic wave receiver 30 on an electromagnetic wave W.

[0021] [Electromagnetic wave receiving device] The electromagnetic wave receiver 30 receives the electromagnetic wave W transmitted by the electromagnetic wave transmitter 20 and demodulates the received electromagnetic wave W into a digital signal. For example, if the digital signal is a digital signal of sound, the electromagnetic wave receiver 30 generates a detection timing based on the synchronization signal data of the electromagnetic wave W received by the electromagnetic wave receiver 30 and demodulates the digital signal of sound.

[0022] The above is a description of the configuration of this embodiment.

[0023] <Operation> Next, the operation of the electromagnetic wave communication system 10 of this embodiment will be described with reference to the drawings. First, the overall flow will be described, followed by a specific example of multi-level modulation. As an example, the electromagnetic wave communication system 10 will be used to communicate a sound signal. Furthermore, as mentioned above, the effects of this embodiment will also be explained along with the following description.

[0024] [Overall flow] The overall operation of this embodiment will be described below with reference to Figures 1 and 2. First, the acquisition unit 22 acquires a digital signal related to sound from an external device (not shown) and outputs the acquired digital signal to the conversion unit 24 (multilevel conversion unit 24A).

[0025] Next, the multi-level conversion unit 24A takes the digital signal (communication data) from the acquisition unit 22 as input, converts it to a multi-level according to the multi-level setting by the multi-level setting unit 29A, and outputs it. The synchronization signal level conversion unit 24B outputs a predetermined synchronization signal level according to the synchronization level setting by the synchronization level setting unit 29B.

[0026] Next, the switching unit 26A generates the switching timing between the multi-level data and the synchronization signal data selected by the selector 26B and output to the transmission unit 28, and inputs this timing to the selector 26B. As a result, the selector 26B outputs the synchronization signal data and the multi-level data to the transmission unit 28 at different timings according to the switching timing generated by the switching unit 26A.

[0027] Next, the transmitting unit 28 transmits the data selected and input by the selector 26B on an electromagnetic wave W. That is, the transmitting unit 28 transmits an electromagnetic wave W that indicates the modulation signal for the data.

[0028] Next, the electromagnetic wave receiver 30 receives the electromagnetic wave W transmitted by the transmitting unit 28 (electromagnetic wave transmitter 20), generates a detection timing based on the synchronization signal data of the received electromagnetic wave W, and demodulates the multi-level data into a digital signal. As a result, the electromagnetic wave W received by the electromagnetic wave receiver 30 is demodulated into a digital sound signal.

[0029] The above is a description of the overall operation of this embodiment.

[0030] [Specific examples of multi-level modulation] Next, specific examples of modulated signals will be described with reference to Figures 3, 4, and 5. Figures 4 and 5 are examples of modulated signals transmitted by the electromagnetic wave transmitter 20 of this embodiment, respectively.

[0031] Here, in FIGS. 4 and 5, V represents a voltage value and t represents time. On the axis of the voltage value V, V1, V2, V3, V4, and V5 respectively represent the second voltage value of the second voltage region RB, three levels of the first voltage value within the first voltage region RA, and the third voltage value of the third voltage region RC. The patterns of these modulation signals include multi-valued data and synchronization signal data. Note that the V in FIG. 4 sync1、 V sync2 and V sync3 as well as the V in FIG. 5 sync4 and V sync5 represent the portions corresponding to the synchronization signal data among the modulation signals. Also, the overall pattern in FIG. 5 represents a modulation signal including the portion corresponding to the synchronization signal data and the other portion (the portion corresponding to the modulation data). That is, in this embodiment, the transmission unit 28 transmits a synchronization signal as at least a part of the modulation signal.

[0032] As shown in FIGS. 4 and 5, the signal generated by the conversion unit 24 of this embodiment is a modulation signal using at least one of the voltage values of two or more levels among the first voltage values V2, V3, V4 within the first voltage region RA, the second voltage value V1 of the second voltage region RB, and the third voltage value V5 of the third voltage region RC. That is, the signal generated by the conversion unit 24 of this embodiment is a modulation signal that is multi-valued modulated using voltage values of three or more levels. Specifically, the modulation signal is, for example, a signal that converts m-bit (m≧1, in this embodiment, m = 2 as an example) data into n-level (n≧3, in this embodiment, n = 4 as an example) voltage levels and is multi-valued modulated. Therefore, in the case of this embodiment, compared with the technologies disclosed in the aforementioned Patent Documents 1 and 2 (hereinafter referred to as comparative technologies), the amount of data that can be transmitted in the same time is larger. Therefore, the electromagnetic wave transmission device 20 of this embodiment can increase the transmission speed compared with the comparative technology. Along with this, the electromagnetic wave communication system 10 of this embodiment can increase the communication speed compared with the comparative technology.

[0033] The second voltage region RB and the third voltage region RC are typically considered non-oscillating regions. A "non-oscillating region" refers to any region in the RTD's voltage-current characteristics other than the voltage region required to oscillate the electromagnetic wave W. However, as shown in Figure 4, in this embodiment, the synchronization signal V sync1、 V sync2 , V sync3 The setting includes voltage values ​​in at least one of the second voltage region RB and the third voltage region RC (see Figure 3). A voltage transition that includes voltage values ​​in the second voltage region RB and the third voltage region RC, which are normally considered non-oscillating regions (second voltage value V1 and third voltage value V5), can increase the signal-to-noise ratio compared to, for example, a configuration in which the voltage transition is performed only with voltage values ​​within the normal oscillation region (corresponding to the first voltage region RA). Therefore, the electromagnetic wave transmitter 20 of this embodiment can transmit a signal that is less likely to be falsely detected by the electromagnetic wave receiver 30. Consequently, the electromagnetic wave communication system 10 of this embodiment has high communication stability in terms of the recognizability of the synchronization signal. Furthermore, as mentioned above, the electromagnetic wave transmitter 20 of this embodiment can transmit at a higher speed than the comparative technology, and therefore, the electromagnetic wave transmitter 20 of this embodiment can transmit a signal that is less likely to be falsely detected by the electromagnetic wave receiver 30 while maintaining a higher transmission speed compared to the comparative technology.

[0034] Also, in Figure 4, the synchronization signal V sync1 The voltage value is set to a specific pattern in which the voltage value transitions from one of the minimum voltage value (second voltage value V1) and the maximum voltage value (first voltage value V4) to the other (a pattern in which the voltage value transitions in the order V1, V2, V3, V4 or in the reverse order). That is, the synchronization signal V in this embodiment sync1 This pattern includes the maximum voltage value (first voltage value V4) and minimum voltage value (second voltage value V1) among the voltage setting levels within the first voltage region RA. Therefore, the electromagnetic wave receiving device 30 of this embodiment recognizes the maximum and minimum voltage values ​​of the modulated signal to be received. The digital signal is multi-level modulated using voltage values ​​V1, V2, V3, and V4. In Figure 4, the synchronization signal V sync3The voltage value is set to a specific pattern in which the voltage value transitions from one of the minimum voltage value (first voltage value V2) and the maximum voltage value (third voltage value V5) to the other (a pattern in which the voltage values ​​transition in the order V2, V3, V4, V5 or in the reverse order). Synchronization signal V sync2 The voltage values ​​are set to a specific pattern in which they transition from one of the minimum voltage value (first voltage value V2) and the maximum voltage value (second voltage value V1) to the other (a pattern in which the voltage values ​​transition in the order V2, V3, V4, V1, or in the reverse order). The digital signal is multi-level modulated using voltage values ​​V2, V3, V4, and V5. Therefore, the electromagnetic wave transmitter 20 of this embodiment can transmit a synchronization signal that is easily recognized by the electromagnetic wave receiver 30. Consequently, the electromagnetic wave communication system 10 of this embodiment has high communication stability in terms of the recognizability of the synchronization signal.

[0035] Also, the synchronization signal V in Figure 5 sync4、 V sync5 The signal is set to use four levels, which include all possible levels of the multi-level data of the digital signal, encompassing both the voltage values ​​(second voltage value V1 and third voltage value V5) of the second voltage region RB and the third voltage region RC (see Figure 3), which are considered to be the normal non-oscillating regions. Therefore, in this embodiment, by using such a synchronization signal, it becomes possible to transmit the level voltage of the synchronization signal as training data to the electromagnetic wave transmitter 20. Furthermore, the electromagnetic wave receiver 30 can extract each level voltage from the synchronization signal and set the level of the multi-level data of the received signal. Therefore, the electromagnetic wave transmitting device 20 of this embodiment can cause the electromagnetic wave receiving device 30 to recognize the level voltage of the modulated signal.

[0036] In this embodiment, a modulated signal may also be generated using two or more voltage values ​​from among the first voltage values ​​V2, V3, and V4 in the first voltage region RA, as well as both the second voltage value V1 in the second voltage region RB and the third voltage value V5 in the third voltage region. In this case, the signal transitioning from one of the first voltage values ​​V2, V3, or V4 to the second voltage value V1 is considered to be the same signal as the signal transitioning from one of the first voltage values ​​V2, V3, or V4 to the third voltage value V5. In this case, the multi-level conversion unit 24A (conversion unit 24) of this embodiment transitions the signal from one of the first voltage values ​​V2, V3, and V4 to either the second voltage value V1 or the third voltage value V5, transitioning the signal to the value that results in a shorter transition time. For example, if one of the first voltage values ​​V2, V3, and V4 is the first voltage value V2, the multi-level conversion unit 24A transitions the signal to the second voltage value V1, which results in a shorter transition time. Also, for example, if one of the first voltage values ​​V2, V3, and V4 is the first voltage value V4, the multi-level conversion unit 24A transitions the signal to the third voltage value V5, which results in a shorter transition time. Therefore, in this embodiment, when generating a modulated signal using the voltage value of the first voltage region RA and the voltage values ​​of both the second voltage region RB and the third voltage region, the transmission speed (communication speed) can be increased by shortening the transition time as described above.

[0037] As described above, this embodiment has been explained as an example of the present invention, but the present invention is not limited to this embodiment. The technical scope of the present invention also includes, for example, the following forms (modifications).

[0038] For example, in this embodiment, three voltage levels within the first voltage region RA were described as set voltage levels. However, it is sufficient for there to be two or more set voltage levels within the first voltage region RA.

[0039] Furthermore, in this embodiment, the pattern of the synchronization signal is shown in V in Figure 4. sync1 , V sync2 , V sync3 and V in Figure 5 sync4 , V sync5 Although explained above, the synchronization signal pattern may differ from these patterns. In this embodiment, the synchronization signal pattern is shown in Figure 4, Vsync1 , V sync2 , V sync3 and V in Figure 5 sync4 , V sync5 This was explained as an example. However, any form that falls within the technical scope of the present invention may include any one of these synchronization signal patterns or a variation thereof. That is, the synchronization signal may be any one of the following: (1) a signal that includes the second voltage value V1 of the second voltage region RB but does not include the third voltage value V5 of the third voltage region RC; (2) a signal that does not include the second voltage value V1 of the second voltage region RB but includes the third voltage value V5 of the third voltage region RC; and (3) a signal that includes the second voltage value V1 of the second voltage region RB and the third voltage value V5 of the third voltage region RC.

[0040] Furthermore, in this embodiment, the multi-level conversion unit 24A was described as transitioning the signal from one of the first voltage values ​​V2, V3, and V4 to either the second voltage value V1 or the third voltage value V5, in the case of the transition that shortens the transition time. However, for example, the following may also be done. Specifically, when transitioning the signal from one of the first voltage values ​​V2, V3, and V4 to one of the first voltage values ​​V2, V3, and V4 via either the second voltage value V1 or the third voltage value V5, the signal may be transitioned in the case of the transition that shortens the transition time. In this modified case, when generating a modulated signal using the voltage value of the first voltage region RA and the voltage values ​​of both the second voltage region RB and the third voltage region RC, the transmission speed (communication speed) can be increased by shortening the transition time in the manner described above.

[0041] Examples of reference formats are provided below. 1. A transmitting unit that transmits electromagnetic waves indicating a modulated signal, wherein the voltage-current characteristics have a maximum value and a minimum value located on the voltage side higher than the maximum value. An acquisition unit that acquires digital signals, A modulation unit modulates the aforementioned digital signal using at least one of two first voltage values ​​in a first voltage region defined as a voltage range greater than or equal to the maximum voltage and less than or equal to the minimum voltage, a second voltage value in a second voltage region defined as a voltage range less than the maximum voltage, and a third voltage value in a third voltage region defined as a voltage range higher than the minimum voltage, and modulates the aforementioned modulated signal. An electromagnetic wave transmitting device equipped with the following features. 2. The modulation unit modulates the digital signal into the modulated signal using the first voltage value, the second voltage value, and the third voltage value. 1. The electromagnetic wave transmitting device described in item 1. 3. The transmitting unit transmits a synchronization signal as at least a part of the modulated signal. 1. or 2. An electromagnetic wave transmitting device as described in 1. or 2. 4. The synchronization signal includes a pattern that transitions from the first voltage value to at least one of the second voltage value and the third voltage value, or from at least one of the second voltage value and the third voltage value to the first voltage value. 3. Electromagnetic wave transmitting device. 5. The synchronization signal is a signal using the first voltage value, the second voltage value, and the third voltage value, which are at two or more levels. 3. or 4. An electromagnetic wave transmitting device as described in 3. or 4. 6. The modulation unit modulates the digital signal into the modulated signal using the first voltage value, the second voltage value, and the third voltage value. An electromagnetic wave transmitting device described in any one of items 1-4. 7. The signal transitioning from any one of the first voltage values ​​to the second voltage value and the signal transitioning from any one of the voltage values ​​to the third voltage value represent the same signal. When the modulation unit transitions the signal from any one of the above voltage values ​​to either the second voltage value or the third voltage value, it transitions the signal to the value that results in a shorter transition time. 5. Electromagnetic wave transmitting device. 8. The signal transitioning from any one of the first voltage values ​​to the second voltage value and the signal transitioning from any one of the voltage values ​​to the third voltage value represent the same signal. When the modulation unit transitions a signal from any one of the above voltage values ​​to any one of the above voltage values ​​via either the second voltage value or the third voltage value, it transitions the signal to the one that results in a shorter transition time. 5. Electromagnetic wave transmitting device. 9. The electromagnetic wave is a terahertz wave. An electromagnetic wave transmitting device described in any one of items 1 to 7. 10. An electromagnetic wave transmitting device described in any one of items 1 to 8, An electromagnetic wave receiving device that receives electromagnetic waves transmitted by the aforementioned electromagnetic wave transmitting device and demodulates them into a digital signal, An electromagnetic wave communication system equipped with [the necessary components].

[0042] This application claims priority based on Japanese Patent Application No. 2019-001973, filed on 9 January 2019, and incorporates all of its disclosures herein. [Explanation of Symbols]

[0043] 10 Electromagnetic wave communication systems 20 Electromagnetic wave transmitting device 22 Acquisition Department 24. Conversion section (an example of a modulation section) 24A Multi-level conversion unit 24B Synchronization signal level conversion section 26A Switching section 26B Selector 28 Transmitter 29A Multi-level setting section 29B Synchronization Level Setting Section 30 Electromagnetic wave receiving device RA First voltage region RB Second Voltage Region RC third voltage region W Electromagnetic waves (an example of terahertz waves)

Claims

[Claim 1] A transmitting unit that transmits electromagnetic waves indicating a modulated signal, wherein the voltage-current characteristics have a maximum value and a minimum value located on the voltage side higher than the maximum value, An acquisition unit that acquires digital signals, A modulation unit modulates the aforementioned digital signal using at least one of two first voltage values ​​in a first voltage region defined as a voltage range greater than or equal to the maximum voltage and less than or equal to the minimum voltage, a second voltage value in a second voltage region defined as a voltage range less than the maximum voltage, and a third voltage value in a third voltage region defined as a voltage range higher than the minimum voltage, and modulates the modulated signal. An electromagnetic wave transmitting device equipped with the following features.

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