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 an electromagnetic wave W indicating a modulated signal, which has 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 to the modulated signal using three or more voltage values ​​within an oscillation region which is a voltage region above the maximum value and below the minimum value. The transmitting unit 28 preferably transmits a synchronization signal as at least a part of the modulated signal. In this case, the synchronization signal preferably includes the maximum and minimum values ​​among the three or more voltage values, and includes a pattern that transitions from one of the maximum and minimum values ​​to the other.

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 with a signal using three or more voltage levels within an oscillation region defined as a voltage range greater than or equal to the maximum voltage and less than or equal to the minimum voltage, 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 four levels within the oscillation region. [Figure 4] This is an example of a modulated signal transmitted by the electromagnetic wave transmitting device of this embodiment. [Figure 5] This is another example of a modulated signal transmitted by the electromagnetic wave transmitting device of this embodiment.

Best Mode for Carrying Out the Invention

[0010] <Summary> Hereinafter, this 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 this embodiment will be described with reference to the drawings. Next, the operation of the electromagnetic wave communication system 10 of this embodiment will be described with reference to the drawings. The effects of this 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 this 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.

[0012] The electromagnetic wave W of this embodiment is an electromagnetic wave indicating a modulation signal described later. Further, the electromagnetic wave W of this 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) metal, 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 transmission device 20 of the present embodiment. The electromagnetic wave transmission device 20 has a function of transmitting an electromagnetic wave W indicating a multi-valued modulated modulation signal. The electromagnetic wave transmission 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-valued level setting unit 29A, and a synchronization level setting unit 29B.

[0014] (Acquisition Unit) The acquisition unit 22 of the present embodiment has a function of acquiring digital signals such as sound and video as an example. Further, the acquisition unit 22 has a function of outputting the acquired digital signal to the conversion unit 24.

[0015] (Conversion Unit)[[ID=(11]] The conversion unit 24 of the present embodiment includes, as an example, a multi-valued level conversion unit 24A and a synchronization signal level conversion unit 24B. The multi-valued level conversion unit 24A has a function of inputting a digital signal (communication data) from the acquisition unit 22 and converting and outputting it to a multi-valued level according to the multi-valued level setting. Here, the multi-valued level setting means setting of three or more voltage levels within the oscillation region RA (see FIG. 3) described later. Further, the synchronization signal level conversion unit 24B has a function of outputting a predetermined synchronization signal level according to the synchronization level setting. Here, the synchronization level setting means setting of three or more voltage levels within the oscillation region RA (see FIG. 3).

[0016] (Switching Unit and Selection Unit) The switching unit 26A has a function of generating a switching timing of data selected by the selector 26B and output to the transmission unit 28, and inputting it to the selector 26B. Here, the data is data output by the multi-valued level conversion unit 24A (hereinafter referred to as multi-valued data) and data output by the synchronization signal level conversion unit 24B (hereinafter referred to as synchronization signal data). The selector 26B has a function of outputting the synchronization signal data and the multi-valued 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 and the voltage values ​​at four levels within the oscillation region RA. 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 OH The 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 oscillation region RA. That is, the RTD has a differential negative resistance region (oscillation region RA) exhibiting differential negative resistance characteristics in its operating region's voltage-current characteristics. The RTD functions as an element that oscillates electromagnetic waves W when a voltage value within the oscillation region RA is applied. Note that both sides of the oscillation region RA in the voltage-current characteristic graph correspond to the non-oscillating region of the RTD. Here, the non-oscillating region of the RTD means the region in the RTD's voltage-current characteristics other than the voltage region for oscillating electromagnetic waves W. In this specification, the voltage value V within the non-oscillating region is OL The region on the lower voltage side is the non-oscillating region RB, and the voltage value V OH The region on the higher voltage side is defined as the non-oscillating region RC.

[0019] Then, when the transmitting unit 28 receives synchronization signal data from the synchronization signal level conversion unit 24B, it transmits a synchronization signal having a pattern corresponding to three or more voltage values ​​within the oscillation region RA. Here, the synchronization signal in this embodiment 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. Next, when the transmitting unit 28 receives multi-level data from the multi-level conversion unit 24A, it transmits a digital signal having a pattern corresponding to three or more voltage values ​​within the oscillation region RA. Here, the three or more voltage values ​​in this embodiment are, as an example, four voltage values.

[0020] As described above, the multi-level setting and synchronization level setting in this embodiment are set to the voltage values ​​of four levels within the oscillation region RA. Furthermore, the electromagnetic wave transmitter 20 of this embodiment modulates the multi-level data and synchronization signal data using 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, a specific example of the modulation signal will be described while referring to FIGS. 3, 4, and 5. FIGS. 4 and 5 are each an example of the modulation signal transmitted by the electromagnetic wave transmission device 20 of the present embodiment.

[0031] Here, in FIGS. 4 and 5, V represents a voltage value and t represents time. V1, V2, V3, and V4 on the axis of the voltage value V each represent four-level voltage values within the oscillation region RA. FIGS. 4 and 5 show examples of the pattern of the modulation signal input to the transmission unit 28 via the selector 26B. These patterns of the modulation signal include multi-valued data and synchronization signal data. Note that V in FIG. 4 sync1 represents a portion corresponding to the synchronization signal data in the modulation signal. Also, V in FIG. 5 sync2 is a case where the synchronization signal data uses four levels that are all the levels that the digital signal can take as multi-valued levels.

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

[0033] Also, as shown in FIG. 4, the portion V corresponding to the synchronization signal data sync1This includes the voltage value V4, which is the maximum voltage setting level, and the voltage value V1, which is the minimum voltage setting level, within the oscillation region RA. Therefore, the synchronization signal is generated using the voltage values ​​within the oscillation region RA. Therefore, in this embodiment, the voltage transition range can be narrowed compared to the case where the synchronous signal and digital signal include the voltage values ​​of the non-oscillating regions RB and RC, as in the comparative technology. Consequently, in this embodiment, the dynamic range of the generation circuits (not shown) of the multi-level conversion unit 24A and the synchronous signal level conversion unit 24B can be reduced compared to the comparative technology. In other words, in this embodiment, the voltage transition time can be shortened compared to the comparative technology. Furthermore, as shown in Figure 5, V uses all the multi-levels that the digital signal can take for the synchronization signal data. sync2 By using this as synchronization signal data, it becomes possible to transmit the level voltage of the synchronization signal as training data to the electromagnetic wave receiver 30. The electromagnetic wave receiver 30 can extract each level voltage from the received synchronization signal and set the level of the multi-level data of the received signal.

[0034] Furthermore, as shown in Figure 4, the portion V corresponding to the synchronization signal data sync1 This includes a voltage value V4 which is the maximum voltage setting level and a voltage value V1 which is the minimum voltage setting level. In other words, the synchronization signal of this embodiment is a pattern that includes the maximum voltage value (voltage value V4) and the minimum voltage value (voltage value V1) among the voltage setting levels within the oscillation region RA. Therefore, the electromagnetic wave receiving device 30 of this embodiment recognizes the maximum voltage value and the minimum voltage value of the modulated signal to be received. Therefore, the electromagnetic wave transmitting device 20 of this embodiment can cause the electromagnetic wave receiving device 30 to recognize the maximum and minimum voltage values ​​of the modulated signal.

[0035] Furthermore, as shown in Figure 4, the portion V corresponding to the synchronization signal data sync1In other words, the synchronization signal pattern is set to a specific pattern in which the voltage value transitions from one of the minimum voltage value (voltage value V1) and the maximum voltage value (voltage value V4) within the oscillation region RA to the other (a pattern in which the voltage values ​​transition in the order V1, V2, V3, V4, or in the reverse order). 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.

[0036] 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).

[0037] For example, in this embodiment, four voltage levels within the oscillation region RA were described as set voltage levels. However, it is sufficient to have three or more set voltage levels within the oscillation region RA.

[0038] Furthermore, in this embodiment, the pattern of the synchronization signal is shown in Figure 4 V sync1 Although explained above, the synchronization signal pattern may be different from these.

[0039] 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 with a signal using three or more voltage levels within an oscillation region defined as a voltage range greater than or equal to the maximum voltage and less than or equal to the minimum voltage, An electromagnetic wave transmitting device equipped with the following features. 2. The transmitting unit transmits a synchronization signal as at least a part of the modulated signal. 1. The electromagnetic wave transmitting device described in item 1. 3. The synchronization signal includes the maximum and minimum values ​​among the three or more voltage levels, and includes a pattern that transitions from one of the maximum and minimum values ​​to the other. 2. Electromagnetic wave transmitting device. 4. The synchronization signal is a signal that uses the voltage values ​​of all levels of the modulation signal. Electromagnetic wave transmitting device as described in 2. or 3. 5. The electromagnetic wave in question is a terahertz wave. An electromagnetic wave transmitting device described in any one of items 1-4. 6. An electromagnetic wave transmitting device described in any one of items 1 to 5, An electromagnetic wave receiving device that receives the electromagnetic waves transmitted by the electromagnetic wave transmitting device and demodulates them into a digital signal, An electromagnetic wave communication system equipped with [the necessary components].

[0040] This application claims priority based on Japanese Patent Application No. 2019-001972, filed on 9 January 2019, and incorporates all of its disclosures herein. [Explanation of symbols]

[0041] 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 oscillation region RB Non-oscillating region RC non-oscillating 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 with a signal using three or more voltage values ​​within an oscillation region that is defined as a voltage region greater than or equal to the maximum voltage and less than or equal to the minimum voltage, An electromagnetic wave transmitting device equipped with the following features.

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