JP5549306B2 - Approach warning sound generator - Google Patents

Description

  The present invention relates to an approach warning sound generating device mounted on a moving body such as a hybrid vehicle or an electric vehicle.

  In the automobile industry, environmental issues such as energy saving and carbon dioxide emission reduction are rapidly progressing, and instead of cars driven only by internal combustion engines (engines) that burn oil, they are driven by electric motors. Electric vehicles and hybrid vehicles are being developed and popularized. A vehicle driven by an electric motor has a much quieter running sound than an internal combustion engine vehicle. In general, it is an advantage that the running sound is quiet, but there is a problem that the pedestrian is safe, that is, the pedestrian is hardly aware of the approach of the vehicle.

  In order to solve the above problems, electric vehicles and hybrid vehicles are equipped with devices that let pedestrians perceive the presence / approach of vehicles by emitting acoustic signals instead of engine sounds called engine simulation sounds to the outside of the vehicle. To be considered.

  Further, as techniques for notifying pedestrians of the approach of a vehicle, techniques as shown in Patent Documents 1 and 2 have been proposed.

JP 2003-173499 A

JP 2009-078632 A

  If the engine simulation sound is emitted as described above, the pedestrian can perceive the presence / approach of the vehicle, but the driving sound can be made quieter by using the electric motor. There is a dilemma in that it is not possible to obtain an effect more than informing the existence of a vehicle. Patent Documents 1 and 2 can transmit information to pedestrians and the like, but use radio waves, so new equipment for transmitting radio waves to the vehicle is required, leading to an increase in cost. There was a problem.

  It is an object of the present invention to provide an approach warning sound generating device that enables transmission of surrounding information of a vehicle while emitting an approach warning sound.

The present invention is an apparatus mounted on a moving body, and includes a main warning sound generating unit that generates a main warning sound, a surrounding information detecting unit that collects information around the moving body, and the surrounding information detecting unit. A modulation signal generation unit that generates a modulation signal that is a signal on which ambient information based on the detected information is superimposed; a synthesis unit that generates an approach warning sound by synthesizing the main warning sound and the modulation signal; and the approach And a sound emitting unit that emits a warning sound to at least the outside of the moving body.
The modulation signal generation unit of the present invention includes an information encoding unit that encodes the surrounding information, a spreading code generation unit that generates a spreading code including a pseudo noise signal, and the encoded surrounding information of the spreading code And a modulation unit that modulates at.

Furthermore, the present invention is an apparatus mounted on a moving body, wherein a main warning sound generating unit that generates a main warning sound, a surrounding information detecting unit that collects information around the moving body, and the surrounding information detection An information encoding unit that encodes surrounding information based on information detected by the unit, a spreading code generating unit that generates a spreading code composed of a pseudo-noise signal, and modulating the spreading code with the encoded surrounding information A modulation unit that generates a modulation signal; a synthesis unit that synthesizes the main warning sound and the modulation signal to generate an approach warning sound; and a sound emitting unit that emits the approach warning sound to at least the outside of the moving body And.

In the above invention, the sound emitting unit includes a plurality of speakers each directed in a different direction, and the approach warning sound is selected from the plurality of speakers according to the content of information detected by the ambient information detecting unit. It may be determined whether the sound is emitted from the speaker.

In the above invention, the moving body is an electric motor and an internal combustion engine, or a vehicle driven by only the electric motor, and the main warning sound is a sound imitating an operating sound of the internal combustion engine, and the main warning sound generating unit May generate the main warning sound when the moving speed of the moving body is equal to or lower than a predetermined speed .

In the above invention, the surrounding information detection unit measures one or both of the distance and speed of another moving body approaching the moving body, and based on the detection result of the surrounding information detection unit, the other moving body. A risk level determination unit that determines the risk level and outputs it as the ambient information may be further included.

  According to the present invention, it is possible to notify a pedestrian or the like of the approach of a moving body with an approach warning sound, and it is possible to transmit surrounding information superimposed on the approach warning sound. For example, by superimposing the approach information of another moving body as the surrounding information, it is possible to notify the approach of the moving body itself and also transmit the approach of another vehicle.

The block diagram of the approach warning sound generator which is embodiment of this invention The figure which shows the frequency characteristic of the approach warning sound which the approach warning sound generator emits The figure which shows the structural example of the distance and speed sensor of an approach warning sound generator The figure which shows the operation example of the vehicle to which the approach warning sound generator was applied The figure which shows the operation example of the vehicle to which the approach warning sound generator was applied The figure which shows the structural example of an information receiver The figure which shows the structural example of the modulation | alteration part of an approach warning sound generator

FIG. 1 is a block diagram of an approach warning sound generator according to an embodiment of the present invention. The approach warning sound generation device 10 is mounted on a moving body such as a hybrid vehicle, an electric vehicle or the like that has a quiet running sound, emits an approach warning sound to the outside of the moving body, and the vehicle approaches a pedestrian or the like. It is a device that alerts you to alert you. As the approach warning sound, a sound that a pedestrian intuitively recalls the moving body is used. When the moving body is an automobile (hybrid vehicle, electric vehicle, etc.), engine simulation sound simulating the engine sound of a gasoline engine (internal combustion engine) is used. Also, in the case of a car, when driving at a speed above a certain level, a sound such as a friction noise between the tire and the road surface (road noise) is generated at a volume that makes a pedestrian notice the approach, so an approach warning sound Is not always necessary. Therefore, when the moving body is an automobile, an approach warning sound is generated when the vehicle travels at a low speed of approximately 20 km / h or less.
Furthermore, the approach warning sound generator of the present invention includes a surrounding information detection unit that collects information around the vehicle in addition to alerting pedestrians and the like with the approach warning sound, and approaches the detected surrounding information. Superimpose on the warning sound. Thereby, the surrounding information is transmitted simultaneously by emitting the approach warning sound.

  In FIG. 1, the approach warning sound generator 10 includes an engine simulation sound generator 11, an ambient information detector 12, an information encoder 13, a modulator 14, an adder 15, and a speaker 16. The engine simulation sound generator 11 is a functional unit that generates an acoustic signal imitating the engine sound of a gasoline engine. The engine simulation sound may be a reproduction of an actual gasoline engine sound recorded, or a sound signal approximating the engine sound may be synthesized using a sound source.

  The surrounding information detection unit 12 is a functional unit that detects information around the vehicle. For example, a distance / speed sensor that detects the speed and distance of another vehicle approaching the vehicle, an object sensor that detects an obstacle, and the like are preferably used as the surrounding information detection unit 12. However, the surrounding information detection unit 12 is not limited to a distance / speed sensor or an object sensor. For example, vehicle-to-vehicle communication with surrounding vehicles, road-to-vehicle communication with roadside equipment, and the like can be applied.

  The information encoding unit 13 is a functional unit that converts information detected by the surrounding information detection unit 12 into a code that can be superimposed on an acoustic signal. The modulation unit 14 is a functional unit that generates an audio signal (modulation signal) on which the information code input from the information encoding unit 13 is superimposed. As a modulation method, for example, various methods such as a spread spectrum modulation in which a pseudo noise signal such as an M-sequence is phase-modulated with an information code, a method in which a carrier signal is FSK modulated or AM-modulated with an information code can be used.

  The addition unit 15 is a functional unit that adds and synthesizes the engine simulation sound generated by the engine simulation sound generation unit 11 and the modulation signal generated by the modulation unit 14 and outputs an approach warning sound that is a synthesized sound. This approach warning sound is emitted to the outside by the speaker 16. The speaker 16 is mainly installed toward the front of the vehicle, but may be further installed toward the rear and side of the vehicle, and may be further installed in the passenger compartment. In the example of FIGS. 3 and 4, the speakers 16 are installed outward on the front, rear, left and right sides of the vehicle.

  Moreover, the engine simulation sound generation part 11 may acquire speed information from the speed sensor of a vehicle, and may control an engine simulation sound based on this speed information. For example, you may control the magnitude | size and sound quality of engine simulation sound according to speed. Further, the engine simulation sound may be stopped when the vehicle is traveling at a certain high speed. In this case, the modulation unit 14 may stop outputting the modulation signal in response to the stop of the engine simulation sound, or the modulation signal may be always output regardless of the presence or absence of the engine simulation sound.

  FIG. 2 is a diagram illustrating frequency characteristics of the approach warning sound. FIG. 6A is a diagram showing an example of an approach warning sound in which the frequency band of engine simulation sound and the frequency band of modulation signal are separated. By appropriately selecting the modulation method, carrier frequency, etc., the frequency band of the modulation signal can be arranged in the high sound range, and the frequency spectrum should not overlap with the engine simulation sound as shown in the figure. Is possible. Reliability of information transmission by modulation signal by arranging engine simulated sound in audible band (0 to tens of kHz) and modulating signal in non-audible band (more than tens of kHz) and separating these occupied frequency bands The degree can be improved. This is particularly preferable when a modulation scheme that is sensitive to noise is used.

  FIG. 2B is a diagram illustrating an example of an approach warning sound in which the frequency band of the engine simulation sound and the frequency band of the modulation signal are overlapped. The engine simulation sound is not a musical sound but a kind of noise, so even if the modulation signals are overlapped, the listener is not particularly uncomfortable. Therefore, if the modulation method of the modulation signal is a noise-resistant method (for example, spread spectrum method), the structure of the modulation unit is simplified by not separating the engine simulated sound and the frequency band of the modulation signal as shown in the figure In addition, the occupied frequency band of the entire approach warning sound can be narrowed, and it is not necessary to use a broadband audio circuit including a speaker.

  As described above, the approach warning sound generation device of this embodiment emits the approach warning sound generated by synthesizing the modulation signal on which the information around the vehicle is superimposed with the engine simulation sound. As a result, a pedestrian or the like can perceive the approach of the vehicle by sound similar to the engine sound. Further, the information receiving device can receive information about the vehicle surroundings embedded in the engine simulated sound. Reception and decoding can be performed, and an operation according to this information can be performed.

  FIG. 3 is a diagram illustrating an example of the surrounding information detection unit 12. In this figure, a distance / speed sensor 20, a distance / speed detection unit 21, and a risk determination unit 22 are provided as the surrounding information detection unit 12. The distance / speed sensor 20 is provided outwardly on the front, rear, left, and right sides of the automobile as a moving body. As the distance / speed sensor 20, for example, a millimeter wave radar or the like can be used. The millimeter wave radar 20 emits a millimeter wave (30 GHz to 300 GHz) beam wave, receives the reflected wave reflected by the target, and inputs it to the distance / velocity detection unit 21. The distance / velocity detection unit 21 detects the distance and velocity of the target based on the delay of the reflected wave from the original beam wave and the Doppler shift. The target is, for example, another vehicle (automobile) approaching from behind or from the side.

  In the figure, speakers 16 that emit an approach warning sound are also provided outwardly on the front, rear, left and right sides of the vehicle. The speaker 16 may be of any type such as a cone type, a horn type, or a piezoelectric type. Further, if the engine simulation sound can be generated, the speaker 16 having a structure other than an audio speaker such as a buzzer may be used.

Based on the distance and speed of the other vehicle detected by the distance / speed detection unit 21, the risk level determination unit 22 determines the risk level that the other vehicle gives to nearby pedestrians and vehicles. The determination of the risk level is performed based on, for example, a risk level table shown in FIG. The risk level 3 is the “dangerous” state, which is the most dangerous state. The risk level 2 is a “Needs Attention” state that is a moderate risk level. The danger level 1 is a “notification required” state, which is a mild danger state.
In this risk level table, when the distance is less than 10 meters and the speed is 20 km / hour or more, and when the distance is 10 meters or more and less than 25 meters and the speed is 40 km / hour or more, the risk level is 3. Also, when the distance is less than 10 meters and the speed is less than 20 km / hour, when the distance is 10 meters or more and less than 25 meters, when the speed is 20 km / hour or more and less than 40 km / hour, and when the distance is 25 meters or more and less than 50 meters, the speed is 40 km. / Risk level 2 when over time. Moreover, when the distance is 10 meters or more and less than 25 meters and the speed is less than 20 km / hour, and when the distance is 25 meters or more and less than 50 meters and the speed is less than 40 km / hour, the degree of risk is 1. When the distance is 50 meters or more, the risk is not applied because the risk is low regardless of the speed. The risk level determination unit 22 calculates the risk level based on the risk level table and inputs the risk level information to the information encoding unit 13.

An example of detection of ambient information using the distance / speed sensor 20 is shown in FIG.
FIG. 4A shows an operation example when the vehicle 1 is stopped. The vehicle 1 is stopped in front of the pedestrian crossing 5. At this time, a passing distance vehicle 3 and a passing vehicle 3 that are vehicles approaching from the rear are detected by the rear distance / speed sensor 20, and a risk corresponding to the distance / speed is superimposed on the engine simulation sound and released from the speaker 16. Sound. At this time, sound is emitted from at least the front speakers of the four speakers 16. As a result, the pedestrian 2 crossing the pedestrian crossing 5 can hear the engine simulation sound that is an approach warning sound, and the information receiving device (see FIG. 6) possessed by the pedestrian 2 has surrounding information (rear side). (Risk level information of the approaching vehicle) can be notified.

FIG. 5B shows an operation example when the vehicle 1 is stopped or traveling at a low speed in the intersection. The vehicle 1 detects the other vehicle 6 approaching the intersection from the intersecting road 9 by the distance / speed sensor 20 provided on the side surface, and superimposes the degree of danger corresponding to the distance / speed on the engine simulation sound. Sound is emitted from the speaker 16. At this time, sound is emitted from at least the front and rear speakers among the four speakers 16. As a result, the pedestrian 2 walking toward the intersection on the road on which the vehicle 1 travels can hear the engine simulation sound that is an approach warning sound, and the information receiving device possessed by the pedestrian 2 The surrounding information (risk level information of the vehicle approaching from the intersection road) can be notified to (see FIG. 6).
Further, in the state of FIG. (B), the vehicle 1 detects a vehicle approaching from the rear as shown in FIG. 4 (A), and notifies the pedestrian walking on the intersecting road 9 toward the intersection. You may do it.

  FIG. 5 shows an operation example when the vehicle 1 is parked at the intersection waiting for a right turn. FIG. 5B shows an operation example when the vehicle 1 is stopped or traveling at a low speed in the intersection. At this time, the rear distance / speed sensor 20 detects a vehicle approaching from the rear, in particular, the passing vehicle 8, and the degree of danger corresponding to the distance / speed is superimposed on the engine simulation sound and emitted from the speaker 16. At this time, sound is emitted from at least the front speakers of the four speakers 16. Thereby, the surrounding information (risk degree information of the passing-through vehicle 8) superimposed on the engine simulation sound that is an approach warning sound can be notified to the other vehicle 7 waiting for a right turn in the oncoming lane.

  The ambient information to be detected is not limited to this. Further, the object to be detected is not limited to other vehicles. For example, it is possible to perform an operation such as finding an obstacle on the side of the road and notifying pedestrians before and after.

  In order to separate and decode the ambient information described above from the engine simulation sound, an information receiving device is required. The information receiving apparatus is incorporated in, for example, a pedestrian's cane or other personal belongings. An example is shown below.

  FIG. 6 is a diagram illustrating an example of an information receiving apparatus that receives ambient information superimposed on engine simulation sound. This figure shows an example in which an information receiving device is incorporated into various articles possessed by a pedestrian. (A) is a diagram showing an example of a cane with an information receiving device built in, (B) is a diagram showing an example of a hearing aid incorporating the information receiving device, and (C) is an information receiving device. It is a figure which shows the example of the portable music player integrated.

  In FIG. 6A, the information receiving apparatus 101 is built in the cane 100. The information receiving apparatus 101 includes a microphone 110, a demodulation unit 111, and a vibration unit 112. The vibration part 112 is built in the hand (grip) 100 </ b> A of the cane 100. The microphone 110 collects sound including an approach warning sound. The demodulator 111 demodulates information included in the approach warning sound from the sound collected by the microphone 110. Information demodulated by the demodulation unit 111 is input to the vibration unit 112. The vibration unit 112 vibrates in a manner corresponding to the content of the input information. This vibration is transmitted to the user's palm through the hand 100 </ b> A of the cane 100. Thereby, various information can be transmitted to the user by vibration.

  For example, the vibration in a mode corresponding to the content of the information is as follows. When the received risk is 1, it vibrates at a long interval, for example, 1 second vibration and 2 second stop interval. When the degree of risk is 2, it vibrates at shorter intervals, for example, 1 second vibration and 1 second stop. When the degree of risk is 3, it vibrates at an even shorter interval or continuously vibrates without a stop period. Moreover, the vibration is strengthened.

  In FIG. 6B, the hearing aid 200 includes a microphone 201, an amplifier 202, and an earphone 203 in order to perform the function of the hearing aid. The microphone 201 picks up surrounding sound and converts it into a signal. The amplifier 202 amplifies this audio signal and outputs it from the earphone 203. Furthermore, the hearing aid 200 includes a demodulator 204, a speech synthesizer 205, and an adder 206 in order to perform the function of the information receiving device. The demodulator 204 receives an audio signal from the microphone 201 and demodulates information superimposed on the approach warning sound included in the audio signal. Information demodulated by the demodulator 202 is input to the speech synthesizer 205. The voice synthesizer 205 synthesizes information voice corresponding to the content of the input information. The synthesized information speech is input to the adding unit 206. The adding unit 206 is inserted between the microphone 201 and the amplifier 202, adds the audio signal collected by the microphone 201 and the information audio synthesized by the audio synthesizing unit 205, and outputs the sum to the amplifier 202. As a result, the user of the hearing aid 200 can amplify the surrounding sound and listen to the sound corresponding to the information sent from the vehicle (approach warning sound generator).

  The information voice corresponding to the content of information is, for example, as follows. When the degree of danger is 1, a voice of “the car is approaching” is synthesized. If the risk is 2, synthesize a voice saying “Car is approaching. When the degree of danger is 3, the voice of “the car is approaching. It is dangerous. Please be careful.” Is synthesized at a high volume. Further, instead of or in addition to the announcement voice as described above, the content of information may be notified by sound effects or melody reproduction.

  In FIG. 6C, the portable music player 300 includes a music playback unit 301, an amplifier 302, and an earphone 303 in order to perform the functions of the portable music player. The music playback unit 301 includes a storage such as a semiconductor memory or a micro hard disk drive, an audio decoder, and an audio decoder. The music file stored in the storage is decoded by the audio decoder and output as an audio stream signal. The amplifier 302 amplifies the audio stream signal reproduced by the music reproducing unit 301, converts it into an analog signal, and outputs it from the earphone 303. Furthermore, the portable music player 300 includes a microphone 304, a demodulator 305, a voice synthesizer 306, and an adder 307 in order to perform the function of the information receiving device. The microphone 304 picks up surrounding sound and converts it into a signal. The demodulator 305 receives an audio signal from the microphone 304 and demodulates information superimposed on the approach warning sound included in the audio signal. Information demodulated by the demodulator 305 is input to the speech synthesizer 306. The voice synthesizer 306 synthesizes information voice according to the content of the input information. The synthesized information speech is input to the adding unit 307. The adding unit 307 is inserted between the music reproducing unit 301 and the amplifier 302, adds the audio stream signal reproduced by the music reproducing unit 301 and the information sound synthesized by the voice synthesizing unit 306, and outputs the sum to the amplifier 302. Thereby, the user of the portable music player 300 can reproduce and listen to desired music, and when the vehicle approaches, the user can hear a sound corresponding to the information sent from the vehicle (approach warning sound generator). You can listen to the music being played. In addition, the information audio | voice according to the content of information may be the same as that of the case of the hearing aid 200.

  The microphone 304 may be provided on the main body of the portable music player 300. However, the microphone 304 may be provided integrally with the earphone 303 so that ambient sounds can be collected more easily, or only the microphone 304 may be provided separately and the chest of clothes. Or it may be attached near the collar.

  Although the filter is not shown in the block diagram of FIG. 6, it is necessary to pass a necessary signal and block unnecessary signals in accordance with the frequency band of the target audio signal, the frequency band of the modulation signal, and the like. A filter (high pass filter, low pass filter, band pass filter, band cut filter) may be inserted as appropriate.

  Further, the information receiving device is not limited to those possessed by pedestrians or the like. For example, an information receiving device fixed at a certain point on the road may be provided. For example, it is possible to provide an information receiving device in a road monitoring device and perform road traffic monitoring.

<Description of modulation method>
Here, the configuration of the modulation unit 14 will be described. The modulation method performed by the modulation unit 14 is not limited, but a robust method resistant to noise and Doppler shift is preferable. Here, the configuration of a modulation unit that performs differential encoding spread spectrum modulation will be described.

  FIG. 7A is a diagram illustrating a configuration example of the modulation unit 14. The spread code generator 36 generates a spread code. As the spreading code, a pseudo-random code string having a fixed cyclic period such as an M series is used. This spread code is input to the multiplier 37. The information code encoded by the information encoding unit 3 is also input to the multiplier 37. This information code is adjusted in period so that one symbol period coincides with one cyclic period of the spread code.

  The multiplier 37 multiplies the information code and the spread code. This process is generally called spread spectrum modulation. By this spread spectrum modulation, the spread code is phase-modulated by the value (1/0) of the information code every cyclic period, and the frequency spectrum of the information code is spread.

  The spread code modulated by the information code is converted into a differential code by the differential encoding unit 38. The differential encoding process performed by the differential encoding unit 38 is a process of replacing the value of each chip of the spread code with a value representing a change from the previous chip from its absolute value. By this differential encoding, the demodulation unit on the reception side can demodulate the symbol with high accuracy using delay detection even if there is no clock that is accurately synchronized with the transmission side.

  FIG. 7B is a diagram illustrating an example of the differential encoding unit 38. The differential encoding unit 38 includes an XOR circuit 45 to which a spread code is input, and a one-chip delay circuit 46 that delays the output of the XOR circuit 45 by one chip and returns it to the other input terminal of the XOR circuit 45. . By feeding back the output of the XOR circuit 45 with a delay of one chip, the XOR circuit 45 uses the comparison result between the input spread code and the output of the XOR circuit 45 one clock before (the previous chip) as a differential code. Output. In other words, the XOR circuit 45 replaces the absolute value of each chip of the spread code with a differential code indicating the presence / absence of a phase change with respect to the immediately preceding differential code chip, and outputs the result. This is differential encoding.

  The differential code is input to the upsampling unit 39. The upsampling unit 39 upsamples the input code string. That is, one chip is divided into a plurality of (N) chips. The chip rate and bandwidth of the spread code to be transmitted (sounded) are determined by the chip rate of the spread code generated by the spread code generator 36 and the upsampling rate N in the upsampling unit 39.

  The upsampled differential code is multiplied by a carrier signal in a multiplier 42 and is frequency shifted to a high frequency. The upsampling differential code shifted to the high sound range by the carrier signal is added and synthesized with the engine simulation sound by the adder 34 as a modulation signal. This synthesized signal is output as an approach warning sound.

  Note that the upsampling process (upsampling unit 39) and the frequency band shift process (carrier signal generating unit 41, multiplier 42) are not essential for generating the modulation signal. When the frequency band shift process is performed on the modulation signal, the approach warning sound has frequency characteristics as shown in FIG. 2A. When the frequency band shift process is not performed on the modulation signal, the approach warning sound is shown in FIG. ).

  In the above embodiment, when it is not desired to make noise during night driving, the volume of the main warning sound may be reduced or stopped, and the modulation signal may be emitted at a normal volume.

  In the above embodiment, the approach warning sound is obtained by adding and synthesizing the modulation signal modulated with the information code to the engine simulation sound that is the main warning sound. However, the engine simulation sound may be directly modulated with the information code. In this case, for example, a frequency spectrum shift method or the like is used as the modulation method.

  Further, instead of the engine simulation sound, a spreading code string such as an M-sequence may be emitted as an approach warning sound as it is, and information may be superimposed on this spreading code. By processing the frequency characteristics of the spread code to resemble the engine sound, even if the spread code is used as it is as an approach warning sound, it is possible to make a warning sound that a general pedestrian can react intuitively.

  In addition, a mobile body is not limited to a motor vehicle (four-wheeled vehicle). For example, even a vehicle can be used for a light vehicle such as a two-wheeled vehicle or a bicycle. The present invention can also be applied to skateboards, snowboards, humans (pedestrians, runners, skateboarders, skiers, etc.) and dogs.

  In this case, when applied to a moving body other than an automobile, an approach warning sound that matches the moving body may be used. Also, sounds such as bells, chimes, and buzzers may be used as approach warning sounds.

DESCRIPTION OF SYMBOLS 10 Approach warning sound generator 11 Engine simulation sound (main warning sound) generation part 12 Ambient information detection part 101 Information reception apparatus 111,204,305 Demodulation part

Claims (6)

A device mounted on a moving body,
A main warning sound generating section for generating a main warning sound;
An ambient information detector that collects information around the mobile body;
A modulation signal generation unit that generates a modulation signal that is a signal on which surrounding information based on information detected by the surrounding information detection unit is superimposed ;
A synthesis unit for synthesizing the main warning sound and the modulation signal to generate an approach warning sound;
A sound emitting unit for emitting the approach warning sound to at least the outside of the moving body;
An approach warning sound generator with The modulation signal generator is
An information encoding unit for encoding the surrounding information;
A spreading code generator for generating a spreading code consisting of a pseudo noise signal;
A modulator for modulating the spreading code with the encoded ambient information;
The approach warning sound generator according to claim 1 , comprising: A device mounted on a moving body,
A main warning sound generating section for generating a main warning sound;
An ambient information detector that collects information around the mobile body;
An information encoding unit that encodes surrounding information based on the information detected by the surrounding information detection unit ;
A spreading code generator for generating a spreading code consisting of a pseudo noise signal;
A modulation unit that modulates the spreading code with the encoded ambient information to generate a modulation signal ;
A synthesis unit for synthesizing the main warning sound and the modulation signal to generate an approach warning sound;
A sound emitting unit for emitting the approach warning sound to at least the outside of the moving body;
An approach warning sound generator with The sound emitting unit includes a plurality of speakers each directed in different directions, and the approach warning sound is emitted from any of the plurality of speakers according to the content of information detected by the surrounding information detecting unit. The approach warning sound generator according to any one of claims 1 to 3, wherein the approach warning sound generator determines whether or not to do so. The moving body is an electric motor and an internal combustion engine, or a vehicle driven only by the electric motor, and the main warning sound is a sound imitating an operation sound of the internal combustion engine,
The approach warning sound generation device according to any one of claims 1 to 4 , wherein the main warning sound generation unit generates the main warning sound when a moving speed of the moving body is equal to or lower than a predetermined speed. The ambient information detection unit measures one or both of the distance and speed of another moving body approaching the moving body,
Based on the detection result of the surrounding information detection unit, a risk level determination unit that determines the risk level of the other moving body and outputs it as the surrounding information,
The approach warning sound generator according to any one of claims 1 to 5 , further comprising:

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