Communication Systems

Abstract

To provide a communication system capable of increasing the number of pieces of information that can be transmitted compared to conventional technology while suppressing an increase in power consumption.SOLUTION: An automatic train control (ATC) device, which is an example of a communication system, includes: an ATC ground device (transmitting device) 3 that transmits an ATC signal containing one or more kinds of low frequency components lower than a carrier frequency f0 and one or more kinds of high frequency components higher than the carrier frequency f0; and an ATC on-board device 5 (receiving device) that receives the ATC signal transmitted from the ATC ground device 3 and extracts the frequency components. Therein, speed limit information is assigned to a combination of the one or more kinds of low frequency components and the one or more kinds of high frequency components.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a communication system for conveying information between a transmitting device and a receiving device. [Background technology]

[0002] An example of a communication system is an automatic train control device (hereinafter referred to as "ATC device"). In an ATC device, train control information such as speed limit information is transmitted by ATC signals from a ground device equivalent to a transmitter to an on-board device equivalent to a receiver. An ATC signal is generally created by modulating a carrier wave with a modulating wave assigned to the train control information, but due to circuit constraints and the like, it is not possible to increase the number of modulating waves, i.e., the number of pieces of train control information that can be transmitted, significantly.

[0003] Therefore, a method of increasing the amount of information that can be transmitted by an ATC device by using two carrier waves has been conventionally known. For example, in the technology described in Patent Document 1, two carrier waves are amplitude-modulated with a modulating wave, and train control information is assigned to a combination of the frequency of the modulating wave and the modulating wave phase difference of the amplitude-modulated wave, thereby increasing the amount of information that can be transmitted by an ATC device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-164241 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, the ground equipment (transmitting equipment) adds (superimposes) and amplifies a signal (amplitude modulated wave) A and a signal (amplitude modulated wave) B, and transmits the result. In other words, the superimposed wave of the two signals is amplified. For this reason, the technology described in Patent Document 1 requires an amplifier with a high saturation level, and there is also a problem that power consumption increases.

[0006] It should be noted that such a problem is not limited to ATC devices, but is common to any communication system that transmits information using a method similar to the conventional method described above.

[0007] Therefore, an object of the present invention is to provide a communication system that can increase the amount of information that can be transmitted compared to the conventional technology while suppressing an increase in power consumption. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a communication system including a transmitting device that transmits a signal including one or more low-frequency components lower than a carrier frequency and one or more high-frequency components higher than the carrier frequency, and a receiving device that receives the signal transmitted from the transmitting device and extracts frequency components, and information is assigned to a combination of the one or more low-frequency components and the one or more high-frequency components. Here, the one or more low frequency components and the one or more high frequency components are frequency components of a spread-modulated wave in which one carrier wave is spread-modulated with a spread code. The transmitting device is configured to select the one or more low frequency components and the one or more high frequency components corresponding to information to be transmitted to the receiving device from a plurality of frequency components stored in advance, perform an inverse fast Fourier transform on the selected one or more low frequency components and the one or more high frequency components, convert them into analog signals, and transmit them, and the receiving device is configured to receive the analog signal transmitted from the transmitting device, convert it into a digital signal, extract frequency components by performing a frequency component extraction process, and grasp the information content of the analog signal based on the extracted frequency components. Alternatively, the transmitting device is configured to spread-modulate one carrier wave with a spreading code, perform a fast Fourier transform to extract frequency components, select one or more low frequency components and one or more high frequency components from the extracted frequency components corresponding to information to be transmitted to the receiving device, perform an inverse fast Fourier transform on the selected one or more low frequency components and one or more high frequency components, convert them into analog signals and transmit them, and the receiving device is configured to receive the analog signal transmitted from the transmitting device, convert it into a digital signal, perform a frequency component extraction process to extract the frequency components, and grasp the information content of the analog signal based on the extracted frequency components. Effect of the Invention

[0009] According to the present invention, it is possible to provide a communication system that can increase the amount of information that can be transmitted compared to the conventional technology while suppressing an increase in power consumption. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing a schematic configuration of an ATC device (communication system) according to an embodiment of the present invention. [Diagram 2] 1 is a diagram showing an example of frequency components contained in a spread spectrum modulated wave obtained by spread-modulating a carrier wave; [Diagram 3] 4 is a diagram showing an example of a frequency component used for information transmission in the ATC device, among frequency components included in the spread spectrum modulated wave. FIG. [Figure 4] FIG. 11 is a diagram showing an example of a correspondence table in which combinations of frequency components are associated with speed limit information. [Diagram 5] 1A and 1B are diagrams comparing the ATC signal of a conventional ATC device and the ATC signal of an ATC device according to an embodiment, where (a) shows the frequency components contained in the ATC signal of the conventional ATC device, and (b) shows the frequency components contained in the ATC signal of the ATC device according to an embodiment. [Figure 6] FIG. 13 is a diagram showing a schematic configuration of an ATC device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Here, an automatic train control device (ATC device) which is an example of a communication system will be described.

[0012] FIG. 1 is a diagram showing a schematic configuration of an ATC device (communication system) according to an embodiment of the present invention. As shown in FIG. 1, the ATC device according to the embodiment includes an ATC ground device 3 installed on the ground and an ATC on-board device 5 mounted on a train T running on a rail R in the direction of an arrow. The ATC ground device 3 corresponds to a transmitting device in the ATC device, and is configured to transmit an ATC signal including one or more low-frequency components lower than a predetermined frequency and one or more high-frequency components higher than the predetermined frequency to the rail R. The ATC on-board device 5 corresponds to a receiving device in the ATC device, and is configured to receive the ATC signal transmitted to the rail R by the ATC ground device 3 via an ATC on-board device (receiver) 4 provided at the front lower part of the train T, and extract the frequency components included in the received ATC signal.

[0013] In this embodiment, the one or more low frequency components and the one or more high frequency components included in the ATC signal are frequency components extracted from one carrier wave, and the predetermined frequency is the frequency of the one carrier wave (carrier frequency). That is, in this embodiment, the ATC ground device 3 transmits an ATC signal including one or more low frequency components lower than the carrier frequency and one or more high frequency components higher than the carrier frequency. Note that the ATC signal only needs to include one or more low frequency components lower than the carrier frequency and one or more high frequency components higher than the carrier frequency, and may include at least two or more of the low frequency components lower than the carrier frequency and the high frequency components higher than the carrier frequency. Preferably, the ATC signal includes two or more low frequency components lower than the carrier frequency and two or more high frequency components higher than the carrier frequency.

[0014] In this embodiment, train control information (here, speed limit information) for controlling the train T is assigned to a combination of the one or more types of low frequency components and the one or more types of high frequency components. In the ATC device, the ATC on-board device 5 receives the ATC signal transmitted from the ATC ground device 3, whereby the train control information (speed limit information) is transmitted from the ATC ground device 3 to the ATC on-board device 5, and the ATC on-board device 5 controls (the running of) the train T on which it is mounted, based on the transmitted train control information (speed limit information).

[0015] The configurations of the ATC ground equipment 3 and the ATC on-board equipment 5 will be specifically described below.

[0016] [ATC ground equipment (transmitting equipment)] In this embodiment, the ATC ground equipment 3 has an oscillator 31, a spread modulation unit 32, a pseudo-noise code (PN code) generating unit 33, a first band-pass filter (first BPF) 34, a first fast Fourier transform unit (first FFT) 35, a selection processing unit 36, an inverse fast Fourier transform unit (IFFT) 37, a digital-to-analog conversion unit (DAC) 38, a first low-pass filter (first LPF) 39, an amplifier unit 40, and a transmission unit 41.

[0017] The oscillator 31 generates a carrier wave C(f0) having a frequency f0. The spread modulation unit 32 spread-modulates the carrier wave C(f0) generated by the oscillator 31 with a spread code. Specifically, in this embodiment, the spread modulation unit 32 spread-modulates the carrier wave C(f0) using the PN code generated by the PN code generation unit 33 as a spread code, and outputs it as a spread modulated wave (SS modulated wave). Although not particularly limited, in this embodiment, the PN code generation unit 33 generates a 15-bit PN code. The spread modulated wave output from the spread modulation unit 32 passes through a first BPF 34 to remove a side lobe, and is then input to a first FFT 35. The first FFT 35 performs a fast Fourier transform on the spread modulated wave (the main lobe) to extract a frequency component (spectrum) included in the spread modulated wave.

[0018] Speed ​​limit information is input to the selection processing unit 36. The speed limit information is information (train control information) to be transmitted from the ATC ground equipment 3 to the ATC on-board equipment 5, and is set, for example, by an information setting unit not shown. When the speed limit information is input, the selection processing unit 36 ​​selects a frequency component corresponding to the input speed limit information from the frequency components of the spread modulated wave extracted by the first FFT 35, and outputs the selected frequency component. In this embodiment, the selection processing unit 36 ​​selects a frequency component corresponding to the input speed limit information based on the following concept and method.

[0019] FIG. 2 is a diagram showing an example of frequency components included in (the main lobe of) the spread modulated wave, that is, an example of frequency components extracted by the first FFT 35. In FIG.

[0020] As described above, in this embodiment, a 15-bit PN code is used as a spreading code for spreading modulating the carrier C(f0). Therefore, in the first FFT 35, as shown in Fig. 2, 14 frequency components are extracted on the frequency side lower than the carrier frequency f0 (i.e., the lower sideband), and 14 frequency components are extracted on the frequency side higher than the carrier frequency f0 (i.e., the upper sideband). The carrier frequency f0 is suppressed when the carrier C(f0) is spread modulated. In addition, the closer to the center (carrier frequency f0) of the main lobe of the spread modulated wave, the higher (larger) and almost constant the amplitude of the frequency component, and the closer to the edge of the main lobe of the spread modulated wave (farther from the carrier frequency f0), the lower (smaller) the amplitude of the frequency component.

[0021] Regarding frequency components, from the viewpoint of information transmission, a higher amplitude is more advantageous for identification at the receiving side (i.e., the ATC on-board device 5) that receives the information than a lower amplitude. The number of frequency components used for information transmission can be arbitrarily set according to the amount of information to be transmitted, and in this embodiment, as shown in FIG. 3, the five frequency components with higher amplitudes (fm1, fm2, fm3, fm4, fm5, fm6, fm7, fm8, fm9, fm10, fm11, fm12, fm13, fm14, fm15, fm16, fm17, fm18, fm19, fm20, fm21, fm22, fm23, fm24, fm25, fm26, fm27, fm28, fm29, fm30, fm31, fm32, fm33, fm34, fm35, fm36, fm37, fm38, fm39, fm40, fm41, fm42, fm43, fm44, fm45, fm46, fm47, fm48, fm49, fm49, fm41 ...3, fm44, fm45, fm46, fm47, fm48, fm49, fm49, fm41, fm43, fm44, fm45, L , fm2 L , fm3 L , fm4 L , fm5 L ) and the five frequency components with higher amplitudes among the 14 frequency components of the upper sideband (fm1 H , fm2 H , fm3 H , fm4 H , fm5 H ) are preset as the frequency components to be used for information transmission.

[0022] Here, the five frequency components of the lower sideband and the five frequency components of the upper sideband are independent of each other. Therefore, each frequency component can be used for information transmission, but by using a combination of frequency components for information transmission instead of each frequency component, it is possible to increase the number of pieces of information that can be transmitted. That is, when each frequency component is simply used for information transmission, only 10 pieces of information can be transmitted, but when a combination of any one of the five frequency components of the lower sideband and any one of the five frequency components of the upper sideband is used for information transmission, 25 (=5×5) pieces of information can be transmitted. Also, when a combination of any one of the five frequency components of one of the lower sideband and the upper sideband and any two of the five frequency components of the other of the lower sideband and the upper sideband is used for information transmission, 100 (5×5C2×2) pieces of information can be transmitted. Furthermore, when a combination of any two of the five frequency components in the lower sideband and any two of the five frequency components in the upper sideband is used for information transmission, 100 (=5C2×5C2) types of information can be transmitted. In other words, by using a combination of one or more frequency components selected from the five frequency components in the lower sideband and one or more frequency components selected from the five frequency components in the upper sideband for information transmission, it is possible to significantly increase the number of pieces of information that can be transmitted.

[0023] There are a plurality of combinations of one or more frequency components selected from the five frequency components of the lower sideband and one or more frequency components selected from the five frequency components of the upper sideband. In this embodiment, the five frequency components of the lower sideband (fm1 L , fm2 L , fm3 L , fm4 L , fm5 L ) and the five frequency components fm1 of the upper sideband H , fm2 H , fm3 H , fm4H , fm5 H ) is used for information transmission. In other words, by assigning different speed limit information to each combination of any two frequency components out of the five frequency components of the lower sideband and any two frequency components out of the five frequency components of the lower sideband, it is possible to transmit up to 100 types of speed limit information from the ATC ground equipment 3 to the ATC on-board equipment 5.

[0024] In this embodiment, the selection processing unit 36 ​​has a correspondence table in which combinations of frequency components are associated with speed limit information (such as inspection speed and speed limit), as shown in FIG. 4. In the correspondence table shown in FIG. 4, five frequency components of the lower sideband (fm1 L , fm2 L , fm3 L , fm4 L , fm5 L ) and the five frequency components of the upper sideband (fm1 H , fm2 H , fm3 H , fm4 H ,fm5 H ) and a different speed limit information is associated with each combination of any two frequency components.

[0025] When speed limit information is input, the selection processing unit 36 ​​is configured to refer to the correspondence table, select a combination of frequency components corresponding to the input speed limit information, and output the selected combination of frequency components. For example, when the input speed limit information is "95 km / h", the selection processing unit 36 ​​selects two frequency components fm2 in the lower sideband. L fm4 L and the two frequency components fm1 of the upper sideband H ·fm2 H For example, when the input speed limit information is "60 km / h", the selection processing unit 36 ​​selects a combination of the two frequency components fm1 and fm2 of the lower sideband.L ·fm2 L and the two frequency components fm2 of the upper sideband H ·fm3 H Select a combination with.

[0026] Returning to Fig. 1, the combination of frequency components selected by the selection processing unit 36 ​​is inverse fast Fourier transformed by the IFFT 37 (i.e., converted into a time waveform), and then converted into an analog signal by the DAC 38. The analog signal output from the DAC 38 has noise and the like removed by the first LPF 39 and is amplified by the amplifier 40, and is then transmitted to the rail R as an ATC signal by the transmitter 41. Therefore, the ATC signal (analog signal) transmitted from the ATC ground equipment 3 (the transmitter 41) includes the two frequency components of the lower sideband and the two frequency components of the upper sideband.

[0027] [ATC on-board equipment (receiving equipment)] In this embodiment, the ATC on-board device 5 has a receiving unit 51, a second bandpass filter (second BPF) 52, a second low-pass filter (second LPF) 53, an analog-to-digital conversion unit (ADC) 54, a second fast Fourier transform unit (second FFT) 55, an information grasping unit 56, and a train control unit 57.

[0028] The receiver 51 receives an ATC signal (analog signal) transmitted from the ATC ground equipment 3 (transmitter 41) to the rail R via the ATC on-board device 4. The second BPF 52 has a passband corresponding to the frequency f0 of the carrier wave C (f0). The ATC signal received by the receiver 51 passes through the second BPF 52 and the second LPF 53 to remove unnecessary frequencies, noise, etc., and is then converted into a digital signal by the ADC 54. The second FFT 55 performs a fast Fourier transform on the digital signal output from the ADC 54 to extract frequency components.

[0029] The information grasping unit 56 compares each frequency component extracted by the second FFT 55 with a preset threshold value, and grasps the information content of the ATC signal received from the rail R via the ATC on-board device 4 based on the frequency components exceeding the threshold value. Specifically, in this embodiment, the information grasping unit 56 has a correspondence table as shown in FIG. 4, similar to the selection processing unit 36. Then, when the information grasping unit 56 finishes comparing each frequency component extracted by the second FFT 55 with the threshold value, it refers to the correspondence table and identifies speed limit information corresponding to the combination of frequency components exceeding the threshold value. The combination of frequency components exceeding the threshold value is usually the combination of five frequency components (fm1, fm2, fm3, fm4, fm5, fm6, fm7, fm8, fm9, fm10, fm11, fm12, fm13, fm14, fm15, fm16, fm17, fm18, fm19, fm20, fm21, fm22, fm23, fm24, fm25, fm26, fm27, fm28, fm29, fm30, fm31, fm32, fm33, fm34, fm35, fm35, fm36, fm37, fm38, fm39, fm40, fm41, fm42, fm43, fm44, fm45, fm46, fm47, fm48, fm49, fm49, fm41, fm41, fm42, fm43, fm44, fm45 ...6, fm47, fm4 L , fm2 L , fm3 L , fm4 L , fm5 L ) and the five frequency components of the upper sideband (fm1 H , fm2 H , fm3 H , fm4 H ,fm5 H ) and any two frequency components.

[0030] In this way, the information grasping unit 56 grasps the information content of the ATC signal received from the rail R via the ATC on-board device 4, i.e., the ATC signal transmitted from the ATC ground device 3 to the rail R. For example, if the frequency component exceeding the threshold value is fm1 L , fm4 L , fm1 H ·fm3 H If so, the information grasping unit 56 grasps that the information content of the ATC signal is speed limit information of 88 km / h. L , fm5 L , fm2 H ·fm5 H If so, the information grasping unit 56 grasps that the information content of the ATC signal is speed limit information of 32 km / h.

[0031] When the information grasping unit 56 grasps the information content of the ATC signal (i.e., speed limit information), it outputs the grasped speed limit information to the train control unit 57. Then, the train control unit 57 controls the running of the train T based on the speed limit information grasped by the information grasping unit 56. For example, if the information content of the ATC signal is speed limit information of 88 km / h, the train control unit 57 controls the train T to run at a speed of 88 km / h or less.

[0032] 5 is a diagram comparing the ATC signal of a conventional ATC device with the ATC signal of the ATC device according to the embodiment. Fig. 5(a) shows frequency components contained in the ATC signal of the conventional ATC device, and Fig. 5(b) shows frequency components contained in the ATC signal of the ATC device according to the embodiment.

[0033] The ATC signal of the conventional ATC device is composed of two amplitude modulated waves in which two carrier waves are amplitude modulated by a modulating wave. If the frequencies of the carrier waves are fc1 and fc2 and the frequencies of the modulating waves are fa and fb, the ATC signal of the conventional ATC device contains the frequency components fc1 and fc2 of the two carrier waves, and two frequency components fa that sandwich the frequency fc1 of one of the carrier waves, as shown in Figure 5(a). L (=fc1-fa) and fa H (=fc1+fa) and the two frequency components fb that sandwich the frequency fc2 of the other carrier wave L (=fc2-fb) and fb H (=fc2+fb). In addition, in the ATC signal of a conventional ATC device, the amplitude of the carrier wave is twice the amplitude of the modulated wave. Therefore, the effective value RMS(V) of the ATC signal of a conventional ATC device is 2×(V 2 +(2V) 2 +V 2 ) 1 / 2 =2×6 1 / 2 In addition, if the output impedance of the transmitter that transmits the ATC signal is R, the transmission power P (W) is (2 × 6 1 / 2 ×V) 2 / R=4×6×V 2 / R.

[0034] In contrast, the frequency components included in the ATC signal of the ATC device according to the embodiment are four (any two frequency components among the five frequency components of the lower sideband and any two frequency components among the five frequency components of the lower sideband) as shown in FIG. 5(b) because the carrier frequency f0 is suppressed. Therefore, the effective value RMS(V) of the ATC signal of the ATC device according to the embodiment is (V 2 +V 2 +V 2 +V 2 ) 1 / 2 = 2 × V, and the transmission power P (W) is (2 × V) 2 / R=4×V 2 / R. That is, in the ATC device according to the embodiment, the transmission power P can be 1 / 6 of that in the conventional ATC device.

[0035] As described above, in the ATC device according to the embodiment, the ATC ground device 3 spread-spectrum modulates one carrier C(f0) with a spreading code (PN code) to obtain a spread-spectrum modulated wave, performs fast Fourier transform on the spread-spectrum modulated wave to extract frequency components, and selects a combination of frequency components corresponding to the speed limit information to be transmitted to the ATC on-board device 5 from the extracted frequency components. The ATC ground device 3 is configured to perform inverse fast Fourier transform on the selected combination of frequency components, convert it to an analog signal, and transmit it as an ATC signal. On the other hand, the ATC on-board device 5 receives the ATC signal (analog signal) transmitted from the ATC ground device 3 via the ATC on-board device 4, converts it to a digital signal, and performs fast Fourier transform to extract the frequency components. The ATC on-board device 5 is configured to grasp the information content of the ATC signal (analog signal), i.e., the speed limit information, based on the extracted frequency components, and control the running of the train T based on the grasped speed limit information.

[0036] Here, the combination of the frequency components is specifically a combination of any two frequency components among the five frequency components with high amplitudes in the lower sideband of the spread spectrum modulated wave and any two frequency components among the five frequency components with high amplitudes in the upper sideband of the spread spectrum modulated wave, and different speed limit information can be associated (assigned) with each combination. In other words, the ATC device according to the embodiment can transmit up to 100 types of speed limit information from the ATC ground device 3 to the ATC on-board device 5.

[0037] Therefore, the ATC device according to the embodiment can transmit more speed control information from the ATC ground device to the ATC on-board device than the conventional ATC device that uses two carrier waves. Also, since only one carrier wave is used, power consumption can be reduced compared to the conventional ATC device.

[0038] In the above embodiment, the speed limit information is associated (assigned) with each combination of any two of five preset frequency components in the lower sideband of a spread spectrum modulated wave obtained by spread-modulating one carrier wave and any two of five preset frequency components in the upper sideband of the spread spectrum modulated wave. However, this is not limited to this. It is sufficient that the speed limit information is associated (assigned) with each combination of one or more frequency components selected from the multiple preset frequency components in the lower sideband and one or more frequency components selected from the multiple preset frequency components in the upper sideband of the spread spectrum modulated wave, and other train control information may be associated (assigned) instead of or in addition to the speed limit information.

[0039] In the above embodiment, the selection processing unit 36 ​​of the ATC ground device 3 selects the frequency components corresponding to the input speed limit information from the frequency components of the spread spectrum modulated wave extracted by the first FFT 35, and outputs the selected frequency components. Specifically, the selection processing unit 36 ​​selects the five frequency components (fm1, fm2, fm3, fm4, fm5, fm6, fm7, fm8, fm9, fm10, fm11, fm12, fm13, fm14, fm15, fm16, fm17, fm18, fm19, fm20, fm21, fm22, fm23, fm24, fm25, fm26, fm27, fm28, fm29, fm31, fm32, fm33, fm34, fm35, fm35, fm36, fm37, fm38, fm39, fm39, fm40, fm41, fm42, fm43, fm44, fm45, fm46, fm47, fm48, fm49, fm49, fm41, fm41, fm42, fm43, fm44, fm45, fm45, fm46, fm47, fm48, fm49, fm49, fm41, fm42, fm43, fm4 ...3, fm44, fm45, fm46, fm47L , fm2 L , fm3 L , fm4 L , fm5 L ) and the five frequency components fm1 of the upper sideband of the spread modulated wave H , fm2 H , fm3 H , fm4 H , fm5 H ), the selection processing unit 36 ​​selects a combination of frequency components corresponding to the input speed limit information, and outputs the selected combination of frequency components. However, the present invention is not limited to this. The selection processing unit 36 ​​selects a combination of frequency components corresponding to the input speed limit information from the five frequency components (fm1 L , fm2 L , fm3 L , fm4 L , fm5 L ) and the five frequency components fm1 of the upper sideband of the spread modulated wave H , fm2 H , fm3 H , fm4 H , fm5 H ) may be pre-stored. In this case, the selection processing unit 36 ​​may be configured to select a combination of frequency components corresponding to the input speed limit information from the pre-stored plurality of frequency components, and output the selected combination of frequency components. In addition, in the ATC ground device 3, the oscillator 31, the spread modulation unit 32, the PN code generation unit 33, the first BPF 34, and the first FFT 35 may be omitted.

[0040] In the above embodiment, the ATC on-board equipment 5 performs a fast Fourier transform on the digital signal output from the ADC 54 using the second FFT 55 to extract frequency components. However, this is not limited to this. As shown in FIG. 6, the ATC on-board equipment 5 may have a filter unit 58 instead of the second FFT 55. The filter unit 58 may extract, for example, five frequency components (fm1, fm2, fm3, fm4, fm5, fm6, fm7, fm8, fm9, fm10, fm11, fm12, fm13, fm14, fm15, fm16, fm17, fm18, fm19, fm20, fm21, fm22, fm23, fm24, fm25, fm26, fm27, fm28, fm29, fm30, fm31, fm32, fm33, fm34, fm35, fm35, fm36, fm37, fm38, fm39 ...6, fm37, fm38, fm39, fm39, fm31, fm32, fm33, fm34, fm35, L , fm2 L , fm3 L , fm4 L , fm5 L) and the five frequency components of the upper sideband (fm1 H , fm2 H , fm3 H , fm4 H ,fm5 H In this case, the information grasping unit 56 compares each frequency component that has passed through the filter unit 58, in other words, each frequency component extracted by the filter unit 58, with a preset threshold value, and grasps the information content of the ATC signal received from the rail R via the ATC on-board device 4 based on the frequency components that exceed the threshold value.

[0041] Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to the above-described embodiments and modifications thereof, and further modifications and changes are possible based on the technical concept of the present invention. [Explanation of symbols]

[0042] 3...ATC ground equipment (transmitting equipment), 4...ATC on-board coil, 5...ATC on-board equipment (receiving equipment), 31...oscillator, 32...spread modulation section, 33...PN code generating section, 34...first band pass filter (first BPF), 35...first fast Fourier transform section (first FFT), 36...selection processing section, 37...inverse fast Fourier transform section (IFFT), 38...digital-to-analog conversion section (DAC), 39...first low pass filter (first LPF), 40...amplification section, 41...transmitting section, 51...receiving section, 52...second band pass filter (second BPF), 53...second low pass filter (second LPF), 54...analog-to-digital conversion section (ADC), 55...second fast Fourier transform section (second FFT), 56...information grasping section, 57...train control section, 58...filter section

Claims

1. A transmitting device for transmitting a signal including one or more low frequency components lower than a carrier frequency and one or more high frequency components higher than the carrier frequency, a receiving device that receives the signal transmitted from the transmitting device and extracts a frequency component; Including, information is assigned to a combination of the one or more low frequency components and the one or more high frequency components; A communication system, wherein the one or more low frequency components and the one or more high frequency components are frequency components of a spread modulated wave in which one carrier wave is spread modulated with a spreading code.

2. 2. The communication system according to claim 1, wherein the one or more low frequency components are one or more frequency components selected from a plurality of preset frequency components in a lower sideband of the spread spectrum modulated wave, and the one or more high frequency components are one or more frequency components selected from a plurality of preset frequency components in an upper sideband of the spread spectrum modulated wave.

3. A transmitting device for transmitting a signal including one or more low frequency components lower than a carrier frequency and one or more high frequency components higher than the carrier frequency; a receiving device that receives the signal transmitted from the transmitting device and extracts a frequency component; Including, information is assigned to a combination of the one or more low frequency components and the one or more high frequency components; the transmitting device is configured to select, from a plurality of frequency components stored in advance, the one or more low frequency components and the one or more high frequency components corresponding to information to be transmitted to the receiving device, perform an inverse fast Fourier transform on the selected one or more low frequency components and the one or more high frequency components, convert them into analog signals, and transmit the analog signals; The receiving device is configured to receive the analog signal transmitted from the transmitting device, convert the analog signal into a digital signal, extract frequency components by performing a frequency component extraction process, and grasp information content of the analog signal based on the extracted frequency components. Communication systems.

4. A transmitting device for transmitting a signal including one or more low frequency components lower than a carrier frequency and one or more high frequency components higher than the carrier frequency; a receiving device that receives the signal transmitted from the transmitting device and extracts a frequency component; Including, information is assigned to a combination of the one or more low frequency components and the one or more high frequency components; the transmitting device is configured to spread-modulate one carrier wave with a spreading code, extract frequency components by performing a fast Fourier transform, select one or more low-frequency components and one or more high-frequency components corresponding to information to be transmitted to the receiving device from the extracted frequency components, perform an inverse fast Fourier transform on the selected one or more low-frequency components and one or more high-frequency components, convert them into analog signals, and transmit the analog signals; The receiving device is configured to receive the analog signal transmitted from the transmitting device, convert the analog signal into a digital signal, extract frequency components by performing a frequency component extraction process, and grasp information content of the analog signal based on the extracted frequency components. Communication systems.

5. 5. The communication system according to claim 3, wherein the receiving device is configured to extract frequency components whose amplitudes exceed a preset threshold.

6. The transmitting device is a ground device installed on the ground, The receiving device is an on-board device mounted on a train to control the running of the train, The information is train control information. A communication system according to any one of claims 1 to 5.

7. 7. The communication system of claim 6, wherein said train control information is speed limit information.

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