JP2016014548A - Portable terminal device, method for calculating wind velocity, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable terminal device capable of calculating wind velocity without relying on increase in the performance of a processing system.SOLUTION: The portable terminal device is configured to have: a sound output unit for outputting a sound whose frequency changes in a prescribed width of time repeatedly at prescribed time intervals; a sound receiving unit for receiving the outputted sound; a sound synthesis unit for synthesizing the sound whose frequency changes in the prescribed width of time and the received sound; a first calculation unit for calculating the cycle of a beat in the synthesized sound; and a second calculation unit for calculating wind velocity using the maximum and minimum values of the calculated cycle of the beat.

Description

  The invention of the present disclosure relates to a mobile terminal device, a method for calculating wind speed, and a program.

  In an anemometer or flow meter that uses sound waves, a technology is known that uses sound to propagate at a speed obtained by adding the wind speed to the sound speed when the sound propagates from the windward to the leeward (for example, patents). Reference 1). In this technique, the wind direction and the wind speed are measured based on the time until the sound emitted from the sound source reaches a sound receiver provided at a position away from the sound source by a predetermined distance.

JP-A-8-110788

However, when measuring wind direction and wind speed using a speaker and microphone mounted on a mobile terminal device such as a smartphone, it is difficult to accurately measure the wind direction and wind speed with the processing capability of the mobile terminal device. Conceivable. Specifically, for example, when the distance between the speaker and the microphone of the mobile terminal device is 0.15 m, it is considered that the sound emitted from the speaker reaches the microphone in a time of about 0.44 milliseconds. That is, if the speed of sound is 1225 (km / h), 1225 (km / h) = 1225000/3600 (m / s) = 340 (m / s)
Therefore, the time T required for arrival is T = 0.15 / 340 = 0.44 (ms).

  In order to measure a short propagation time in this way, a high-precision resolution in timekeeping processing is achieved in a processing system such as a CPU (Central Processing Unit), an audio DSP (Digital Signal Processing), and a microphone of the portable terminal device. Is required. For example, in wind speed calculation processing in a portable terminal device, in order to distinguish between no wind and wind speed of 10 m / s, each sound having a sound speed of 340 m / s without wind and a sound speed of 350 m / s with tail wind reaches the microphone. The time difference between the times (0.441 ms and 0.429 ms, respectively) is resolved, that is, a resolution of 0.012 ms (12 μs) is required. However, with the performance of the processing system used in the portable terminal device, it is not possible to achieve the resolution for performing the timekeeping process with high accuracy. In addition, it is not realistic to adopt a higher-performance processing system for the mobile terminal device.

  The technology disclosed herein has been made in view of the above, and an object thereof is to provide a mobile terminal device capable of calculating the wind speed without depending on the performance of the processing system.

  In one aspect, the mobile terminal device according to the present disclosure, in one aspect, a sound output unit that repeatedly outputs a sound whose frequency changes in a predetermined time width at predetermined time intervals, a sound receiving unit that receives the output sound, A sound synthesizing unit that synthesizes a sound whose frequency changes over a predetermined time width and a received sound, a first calculation unit that calculates a beat cycle in the synthesized sound, and a calculated beat cycle And a second calculation unit that calculates the wind speed using the maximum value and the minimum value.

  According to the technology disclosed herein, it is possible to provide a mobile terminal device capable of calculating the wind speed without depending on the performance enhancement of the processing system.

FIG. 1 is a schematic configuration diagram illustrating a configuration of a mobile terminal device according to an embodiment. FIG. 2 is a functional block diagram illustrating functional units of the mobile terminal device according to the embodiment. FIG. 3 is a schematic diagram illustrating a mobile terminal device according to an embodiment. FIG. 4 is a graph showing the period of beat of synthesized sound in one embodiment. FIG. 5 is a flowchart of processing executed by the mobile terminal processing according to the embodiment. FIG. 6 is a table showing an outline of a table showing a set of a period and direction of beat of synthesized sound in one embodiment.

  First, a mobile terminal device according to an embodiment will be described with reference to the drawings. However, the technology disclosed herein is not limited to the configurations shown in the following embodiments.

As shown in FIG. 1, a mobile terminal device 10 according to the present embodiment includes a display 10a, a speaker 10b, a microphone 10c, a geomagnetic sensor 10d, and a CPU (Central Processing Unit).
10e, ROM (Read Only Memory) 10f, and RAM (Random Access Memory) 10g. Examples of the mobile terminal device 10 include a smartphone having a flat front surface and back surface of the mobile terminal device 10. The above-described units of the mobile terminal device 10 are connected to each other by a bus 10h.

  The display 10a displays the processing results of various programs executed by the CPU 10e. In the present embodiment, for example, information indicating the wind speed and the wind direction calculated by the CPU 10e is displayed. The speaker 10b outputs a sound whose frequency changes at a predetermined frequency drop rate under the control of the CPU 10e. The speaker 10b corresponds to an example of a sound output unit in the present embodiment. The microphone 10c receives the sound output from the speaker 10b. The sound received by the microphone 10c is transmitted to the CPU 10e. The microphone 10c corresponds to an example of a sound receiving unit in the present embodiment.

  In the present embodiment, the geomagnetic sensor 10d is a biaxial electronic compass. When the user holds the mobile terminal device 10 horizontally on the ground, the geomagnetic sensor 10d detects the geomagnetism in the horizontal direction perpendicular to the front-rear direction of the mobile terminal device 10 and the direction on the horizontal plane. Then, the geomagnetic sensor 10d calculates which direction is north based on the detected geomagnetism strength in the two directions. The geomagnetic sensor 10d only needs to be at least a biaxial electronic compass, and a triaxial electronic compass may be used instead. When the geomagnetic sensor 10d is a three-axis electronic compass, in addition to the front-rear direction and the left-right direction, geomagnetism in the vertical direction, that is, the normal direction of the horizontal plane is also detected. For this reason, for example, even when the mobile terminal device 10 is tilted with respect to the horizontal plane, the correct orientation can be calculated by subtracting the tilt and calculating the horizontal geomagnetism.

  The CPU 10e controls and executes various processes such as sound output and synthesis, beat period, wind direction, and wind speed calculation described below. The ROM 10f stores various programs executed by the CPU 10e, sound waveform data output from the speaker 10b, and the like. In the RAM 10g, the program stored in the ROM 10f is developed under the control of the CPU 10e. The RAM 10g stores a set of a beat period calculated by the CPU 10e and an orientation detected by the geomagnetic sensor 10d.

  In FIG. 2, the functional block diagram of the portable terminal device 10 in this embodiment is shown. The CPU 10e functions as the sound synthesis unit 20a, the first calculation unit 20b, the second calculation unit 20c, and the third calculation unit 20d by developing and executing various programs stored in the ROM 10f on the RAM 10g.

  The sound synthesizer 20a synthesizes the sound output from the speaker 10b and received by the microphone 10c and the sound stored in the ROM 10f. The first calculator 20b calculates a beat period in the sound synthesized by the sound synthesizer 20a. Note that the synthesis of the sound and the calculation of the beat period in the synthesized sound can be performed using a known technique, and thus detailed description thereof is omitted here. The second calculation unit 20c specifies the maximum value and the minimum value of the calculated beat period. Further, the second calculation unit 20c calculates the wind speed using the specified maximum value and minimum value. The third calculation unit 20d calculates the wind direction from the set of the calculated beat period and the direction detected by the geomagnetic sensor 10d using the direction included in the set having the maximum value and the minimum value of the beat period. To do.

  FIG. 3 shows a schematic diagram of the mobile terminal device 10 in the present embodiment. FIG. 3 shows a state in which a user (not shown) holds the mobile terminal device 10 so that the front surface 11 and the back surface 12 facing each other are horizontal to the ground. As shown in FIG. 3, when the X, Y, and Z axes, which are three axes orthogonal to each other, are set and the XY plane is a plane parallel to the ground, the front surface 11 and the back surface 12 of the mobile terminal device 10 are parallel to the XY plane. It becomes. Further, the mobile terminal device 10 is rotated around an axis AX parallel to the Z axis by the user.

  In the present embodiment, the user rotates the mobile terminal device 10 in a plane horizontal to the ground as indicated by the arrow in FIG. When the mobile terminal device 10 is rotated in a plane parallel to the ground, the mobile terminal device 10 outputs a sound stored in the ROM 10f from the speaker 10b, that is, a sound whose frequency changes within a predetermined time width, and is output from the speaker 10b. The received sound is received by the microphone 10c.

  For example, when a sound that falls from a high tone to a low tone from the speaker 10b, that is, a sound that changes in frequency at a predetermined frequency drop rate, is output and received by the microphone 10c, the output sound propagates through the air and passes through the microphone. 10c is reached. Sound propagating in the air is affected by wind during propagation. For example, in a positional relationship in which the speaker 10b is located on the windward side and the microphone 10c is located on the leeward side, the propagation speed of sound propagating from the speaker 10b to the microphone 10c is higher than the propagation speed in the case of no wind. Conversely, in a positional relationship where the speaker 10b is located on the leeward side and the microphone 10c is located on the leeward side, the propagation speed of sound propagating from the speaker 10b to the microphone 10c is slower than the propagation speed in the case of no wind.

  Further, the sound stored in the ROM 10f can be regarded as a sound that propagates from the speaker 10b to the microphone 10c in a windless state. Therefore, when wind is blowing in the mobile terminal device 10, a beat is generated when the sound propagated from the speaker 10 b to the microphone 10 c and the sound stored in the ROM 10 f are synthesized. The beat cycle changes depending on the wind speed, that is, the speed at which sound propagates from the speaker 10b to the microphone 10c. In this embodiment, when the mobile terminal device 10 is rotated in a plane horizontal to the ground and the position of the mobile terminal device 10 is changed, the sound propagated from the speaker 10b to the microphone 10c at a plurality of positions is stored in the ROM 10f. Is synthesized with the sound. Then, the wind speed and the wind direction are calculated based on the beat period generated as a result of the synthesis.

In the present embodiment, the beat period generated as a result of the above synthesis using the following formula (1) is calculated.
Here, T is the beat period, Δf is the frequency drop rate of the sound stored in the ROM 10f, L is the distance between the speaker 10b and the microphone 10c of the portable terminal device 10, and t is the current temperature around the portable terminal device 10. , Vw is the current wind speed in the mobile terminal device 10. In the present embodiment, the sound speed is 331 m / s.

When a wind is blowing in the portable terminal device 10, a speaker 10b is located on the windward side and a microphone 10c is located on the leeward side, that is, a beat period generated as a result of synthesis by the portable terminal device 10 in the case of a tailwind is assumed to be Ta. Similarly, let Tb be the period of beat that occurs as a result of synthesis by the mobile terminal device 10 when the speaker 10b is on the leeward side and the microphone 19c is on the leeward side, that is, in the case of headwind. At this time, the following formulas (2) and (3) are obtained from the formula (1).

  In the equations (2) and (3), the values of the temperature t and the wind speed Vw are unknown. Therefore, if the beat periods Ta and Tb are known, the simultaneous equations consisting of the equations (2) and (3) are solved, and the value of the wind speed Vw is obtained. The temperature t is also obtained together with the value of the wind speed Vw.

  FIG. 4 is a graph showing a measurement example of the beat periods Ta and Tb in the present embodiment. In FIG. 4, the frequency drop rate Δf = 23000 Hz / s, the distance L = 0.10 m between the speaker 10 b and the microphone 10 c, the current temperature t = 15 ° C. around the portable terminal device 10, and the current wind speed of the portable terminal device 10. Vw = 10 m / s. In FIG. 4, the horizontal axis represents time (seconds), and the vertical axis represents beat amplitude (dB). As shown in FIG. 4, it can be seen that the beat period Ta measured in the case of the tailwind is longer by ΔT than the beat period Tb measured in the case of the head wind.

  When the mobile terminal device 10 is rotated in a plane horizontal to the ground, the beat period takes a maximum value when the speaker 10b is on the windward side and the microphone 10c is on the leeward side. The beat period takes a minimum value when the speaker 10b is on the lee and the microphone 10c is on the lee. The beat cycle takes a value between the maximum value and the minimum value when the speaker 10b and the microphone 10c are in positions other than the windward or leeward. In addition, when making the portable terminal device 10 1 rotation or more, said maximum value and minimum value can be considered as a maximum value and a minimum value, respectively.

  Therefore, in the present embodiment, when the mobile terminal device 10 is rotated in a plane horizontal to the ground and the position of the mobile terminal device 10 is changed, the wind speed is obtained from the maximum value and the minimum value of the beat period. Furthermore, a wind direction is calculated | required from the azimuth | direction which a geomagnetic sensor shows when the period of a beat becomes the maximum or the minimum.

  FIG. 5 shows a flowchart of processing executed to calculate the wind speed and the wind direction in the mobile terminal device 10 in the present embodiment. In the present embodiment, for example, when an operation for starting the calculation process of the wind speed and the wind direction is received from the user, the CPU 10e starts the process of the flowchart shown in FIG.

  In OP101, the CPU 10e starts timing. The CPU 10e performs time measurement processing using a known technique such as a method of measuring the passage of time using a CPU clock or a real time clock. Next, the process proceeds to OP102. In OP102, the CPU 10e outputs a sound whose frequency changes at a predetermined frequency drop rate stored in the ROM 10f from the speaker 10b. Further, the CPU 10e controls the microphone 10c to receive the sound output from the speaker 10b. When the sound output from the speaker 10b is received by the microphone 10c, the CPU 10e advances the process to OP103.

  In OP103, the CPU 10e acquires data indicating the current direction from the geomagnetic sensor 10d. The CPU 10e stores the acquired azimuth data in the RAM 10g. As a result, the CPU 10e can create a set of the acquired azimuth data and a beat period measured in OP105, which will be described later. Next, the CPU 10e advances the process to OP104.

  In OP104, the CPU 10e synthesizes the sound stored in the ROM 10f and the sound received by the microphone 10c. As a result of superposition of sound waves of each sound in the synthesis of these sounds by the CPU 10e, a beat waveform illustrated in FIG. 4 is obtained. Note that the mobile terminal device 10 may employ a configuration in which a sound signal received by the microphone 10c is passed through a low-pass filter. By adopting such a configuration, a more suitable beat waveform envelope (envelope) is obtained by superposition of sound waves. When a beat waveform is obtained by sound synthesis, the CPU 10e advances the process to OP105.

  In OP105, the CPU 10e measures the beat cycle from the beat waveform obtained in OP103. As illustrated in FIG. 4, in the beat waveform, each overlapped sound is weakened, that is, a time width from a point where the amplitude is minimized to the next weakened point is regarded as a beat period. When the measurement of the beat cycle is completed, the CPU 10e stores the set of the measured beat cycle and the orientation acquired in OP103 in the RAM 10g.

  FIG. 6 illustrates a table showing a set of beat period and direction in this embodiment. The table is stored in the RAM 10g. As shown in FIG. 6, the azimuth | direction acquired in OP103 is preserve | saved in combination with the period (second) of a beat. Thereby, it is possible to know the orientation of the mobile terminal device when the beat period is maximum or minimum, that is, whether the speaker 10b and the microphone 10c are positioned on the windward or leeward, respectively.

  In OP <b> 106, the CPU 10 e determines whether or not the elapsed time since the start of the timing process in OP <b> 101 exceeds a predetermined time. When the elapsed time exceeds the predetermined time (OP106: Yes), the CPU 10e advances the process to OP107. On the other hand, if the elapsed time is equal to or shorter than the predetermined time (OP106: No), the CPU 10e returns the process to OP102 and outputs the sound again from the speaker 10b, acquires the azimuth data in OP103 to OP105, synthesizes the sound, and beats. Measure and save the period of

  In OP107, the CPU 10e ends the timing process started in OP101, and advances the process to OP108. In OP108, the CPU 10e determines the wind speed and direction of the wind passing over the mobile terminal device 10 using the data of the set of the azimuth and beat period stored in the RAM 10g in OP105. In the example of FIG. 6, it can be seen that the beat period has a maximum value of 0.19 in the east-northeast and a minimum value of 0.13 in the west-southwest. Therefore, CPU10e calculates | requires wind speed Vw using said Formula (2), (3).

Further, since the wind can be regarded as blowing from the direction at which the beat period becomes maximum to the direction at which the beat period becomes minimum, the CPU 10e uses the direction that is paired with the beat period to determine the wind direction. decide. That is, it can be considered that the azimuth when the beat period is the maximum is leeward and the azimuth when the beat period is the minimum is leeward. In the example of FIG. 6, it is determined that the east-northeast wind is blowing. After determining the wind speed and direction in OP108, the CPU 10e displays the determined wind speed and direction on the display 10a, and ends the process of this flowchart.

  As described above, the CPU 10e beats the synthesized sound even if it does not have a time resolution equivalent to the time from when the sound whose frequency changes at the frequency drop rate is output from the speaker 10b until it is received by the microphone 10c. It suffices to have a processing capability for calculating the cycle and the wind speed. That is, according to the present embodiment, the wind speed and the wind direction can be calculated while suppressing the processing load on the CPU 10e.

  The above is the description of the present embodiment, but the configuration and processing of the above-described portable terminal device are not limited to the above-described embodiment, and may be variously within a range that does not lose the technical idea of the present invention. Can be changed. For example, in the above description, the wind direction is calculated together with the wind speed. However, the geomagnetic sensor 10d is not provided, and the maximum value (maximum value) and the minimum value (minimum value) of the period of sound synthesis synthesized as described above are used. It is good also as a structure which calculates | requires a wind speed from said Formula (2) and (3) using.

  Further, how the sound stored in the ROM 10f is a sound whose frequency changes can be appropriately configured. That is, in the above description, a sound whose frequency changes at a predetermined frequency drop rate is used. However, for example, a sound whose frequency increases at a predetermined time width, that is, a sound whose frequency changes at a predetermined frequency increase rate, is used instead. May be.

  Furthermore, in the above description, the process of calculating the beat period and the process of detecting the azimuth by the geomagnetic sensor are performed within a predetermined time measured by the CPU 10e. May be used. For example, the mobile terminal device is configured to start the processing based on an operation for starting the calculation of the wind speed by the user. And it can also comprise so that a process may be complete | finished when it determines with the portable terminal device having rotated within the surface parallel to the ground a predetermined number of times based on the direction detected by a geomagnetic sensor.

<Computer-readable recording medium>
A management tool for setting the information processing apparatus in a computer or other machine or device (hereinafter referred to as a computer or the like), a program for realizing an OS or the like can be recorded on a computer-readable recording medium. The function can be provided by causing a computer or the like to read and execute the program of the recording medium. Here, the computer is, for example, a mobile terminal device.

  Here, a computer-readable recording medium is a recording medium that stores information such as data and programs by electrical, magnetic, optical, mechanical, or chemical action and can be read from a computer or the like. Say. Examples of such a recording medium that can be removed from a computer or the like include a flexible disk, a magneto-optical disk, a CD-ROM, a CD-R / W, a DVD, a Blu-ray disk, a DAT, an 8 mm tape, a flash memory, and the like. There are cards. Moreover, there are a hard disk, a ROM, and the like as a recording medium fixed to a computer or the like.

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1)
A sound output unit that repeatedly outputs a sound whose frequency changes in a predetermined time width at predetermined time intervals;
A sound receiving unit for receiving the output sound;
A sound synthesizer that synthesizes the sound whose frequency changes in the predetermined time width and the received sound;
A first calculation unit for calculating a period of beat in the synthesized sound;
A portable terminal device comprising: a second calculation unit that calculates a wind speed using the calculated maximum value and minimum value of the beat period.

(Appendix 2)
A geomagnetic sensor for detecting the orientation of the portable terminal device during propagation of the output sound;
A third calculation unit that calculates a wind direction from a set of the calculated beat period and the detected azimuth using an azimuth included in a set having a maximum value and a minimum value of the beat period; The mobile terminal device according to attachment 1.

(Appendix 3)
A sound whose frequency changes in a predetermined time width is repeatedly output from the sound output unit at a predetermined time interval,
The output sound is received by the sound receiving unit,
Synthesizing the received sound and the stored sound;
Calculating the period of beat in the synthesized sound;
A method for calculating a wind speed using the maximum value and the minimum value of the calculated beat period.

(Appendix 4)
Detecting the orientation of the mobile terminal device at the time of propagation of the output sound by a geomagnetic sensor,
The method according to claim 3, wherein a wind direction is calculated from a set of the calculated beat period and the detected azimuth using an azimuth included in a set having a maximum value and a minimum value of the beat period.

(Appendix 5)
A sound whose frequency changes in a predetermined time width is repeatedly output from the sound output unit at a predetermined time interval,
The output sound is received by the sound receiving unit,
Synthesizing the received sound and the stored sound;
Calculating the period of beat in the synthesized sound;
A program for causing a computer to execute a process of calculating a wind speed using the calculated maximum value and minimum value of the beat period.

(Appendix 6)
Detecting the orientation of the mobile terminal device at the time of propagation of the output sound by a geomagnetic sensor,
The program according to claim 5, wherein a wind direction is calculated from a set of the calculated beat period and the detected azimuth using an azimuth included in a set having a maximum value and a minimum value of the beat period.

DESCRIPTION OF SYMBOLS 10 Portable terminal device 10a Display 10b Speaker 10c Microphone 10d Geomagnetic sensor 10e CPU
10f ROM
10g RAM
20a Sound synthesis unit 20b First calculation unit 20c Second calculation unit 20d Third calculation unit

Claims (4)

A sound output unit that repeatedly outputs a sound whose frequency changes in a predetermined time width at predetermined time intervals;
A sound receiving unit for receiving the output sound;
A sound synthesizer that synthesizes the sound whose frequency changes in the predetermined time width and the received sound;
A first calculation unit for calculating a beat period in the synthesized sound;
A portable terminal device comprising: a second calculation unit that calculates a wind speed using the calculated maximum value and minimum value of the beat period. A geomagnetic sensor for detecting the orientation of the portable terminal device during propagation of the output sound;
A third calculation unit that calculates a wind direction from a set of the calculated beat period and the detected azimuth using an azimuth included in a set having a maximum value and a minimum value of the beat period; The mobile terminal device according to claim 1. A sound whose frequency changes in a predetermined time width is repeatedly output from the sound output unit at a predetermined time interval,
The output sound is received by the sound receiving unit,
Synthesizing the received sound and the stored sound;
Calculating the period of beat in the synthesized sound;
A method for calculating a wind speed using the maximum value and the minimum value of the calculated beat period. A sound whose frequency changes in a predetermined time width is repeatedly output from the sound output unit at a predetermined time interval,
The output sound is received by the sound receiving unit,
Synthesizing the received sound and the stored sound;
Calculating the period of beat in the synthesized sound;
A program for causing a computer to execute a process of calculating a wind speed using the calculated maximum value and minimum value of the beat period.