KR101882069B1 - Offset variable pulse width modulation based visible light communication method using smart devices - Google Patents

Offset variable pulse width modulation based visible light communication method using smart devices Download PDF

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KR101882069B1
KR101882069B1 KR1020160002594A KR20160002594A KR101882069B1 KR 101882069 B1 KR101882069 B1 KR 101882069B1 KR 1020160002594 A KR1020160002594 A KR 1020160002594A KR 20160002594 A KR20160002594 A KR 20160002594A KR 101882069 B1 KR101882069 B1 KR 101882069B1
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width
level pulse
unit widths
unit
high level
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KR20170083298A (en
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차재상
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서울과학기술대학교 산학협력단
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/116—Visible light communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/524—Pulse modulation

Abstract

The present invention relates to a visible light communication method using a flashlight of a smart device, and more particularly, to a method of transmitting visible light data by variable pulse width offset modulation of a visible light signal in a flashlight of a smart device, And more particularly, to a flashlight-based visible light ID and communication method of a smart device. The present invention relates to a communication method for transmitting a signal from a camera flash of a transmitting device to a photodiode or a camera image sensor of a receiving device, wherein a camera flash of the transmitting device includes a high level pulse (Hereinafter, referred to as 'transmission data') including a visible light signal by using a combination of a width of a low level level pulse and a width of a low level level pulse ; And a step of the receiving device receiving the visible light signal through the camera and extracting the transmission data. Thus, as the camera flash of the transmitter device transmits data using the pulse width offset modulation of the visible light signal, a large amount of information can be transmitted in a short time.

Description

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset variable pulse width modulated visible light ID and communication method using a flash device of a smart device,

The present invention relates to a visible light communication method using a flash light of a smart device, and more particularly, to a flash light based on a smart device that transmits visible light data through a flash light of a smart device, A visible light ID (Identification) and a communication method.

Visible Light Communication (VLC), which is one of various wireless communication technologies, is a wireless communication method in which a signal is transmitted in a visible light having a wavelength of 380 to 780 nanometers and is continuously developed due to recent development of light emitting diode technology have. Particularly, such visible light communication technology is applied through a display, an electric signboard, a lighting device, and the like. For example, various information can be provided to a user having a visible light communication receiver through a display device included in a TV, a monitor, a smart device, or the like. In addition, recently developed visible light communication technology may transmit a visible light signal emitted from a camera flash of a smart phone to a camera image sensor or a photodiode of another smart phone to recognize the signal.

 However, since the visible light communication method generally transmits a signal using flicker of visible light which is not perceived by a person, such a transmission method has a limitation in providing a large amount of information in a short time. In addition, since the visible light communication method requires a user who wants to use the visible light communication receiver to purchase a visible light communication receiver separately, it may be inconvenient for general users to use.

On the other hand, when data is transmitted using the smart light of the smart device, transmission / reception may be implemented in the form of an app of a smart device. In this case, a problem may arise in that the symbol duration is not constant , And development of a new transmission structure is needed to solve this problem. Symbol Duration issues and limitations of app type may also suggest new low-speed specifications.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above problems occurring in the prior art, and it is an object of the present invention to provide a smart device, which uses a modulation scheme for varying the pulse width offset of a camera flash, The present invention provides a visible light ID and a communication method based on a smart device camera flash capable of coping with the phenomenon of jitter.

A visible light communication method according to an embodiment of the present invention is a communication method for transmitting a signal from a camera flash of a transmitting device to a photodiode (PD) or a camera image sensor of a receiving device, (Hereinafter, referred to as " transmission data ") using a combination of a width of a high level pulse and a width of a low level pulse within a predetermined range (hereinafter, And outputting the visible light signal; And the receiving device receiving the visible light signal through the camera and extracting the transmission data.

The frame may consist of M unit widths, and the width of the high level pulse and the width of the low level pulse may all be comprised of at least P consecutive unit widths, where M is M > 2 * P is an integer).

Level width of the high-level pulse or the width of the low-level pulse can be expanded to P or more is defined as an expandable unit width, and when the number of expandable unit widths is defined as W, W = M ?? 2 * P (where W is an integer of 1 or more).

The number W of expandable unit widths may have one of 1, 3, 7, 15, ..., 2 n -1, ..., where n is an integer of 1 or more.

When the number W of expandable unit widths is 2 n -1, the maximum number of bits in which the pulse width combination in the one frame can be expressed may be 2 n + 1 .

Wherein the pulse width combination is a forward combination in which the high level pulse precedes and the low level pulse follows; And a reverse combination in which the low level pulse precedes and the high level pulse follows.

The forward combination is such that when the width of the high level pulse increases from P unit widths to P + W unit widths, the width of the low level pulse is P unit widths in P + W unit widths, Lt; / RTI >

The reverse combination is such that when the width of the low level pulse increases from P unit widths to P + W unit widths, the width of the high level pulse is P unit widths in P + W unit widths, Lt; / RTI >

The number W of expandable unit widths may be seven.

In the forward combination, when the width of the high level pulse is P unit widths and the width of the low level pulse is composed of P + 7 unit widths, the binary number 0000 value (hexadecimal number 0) Level pulse has a unit width of P + 1, and the width of the low-level pulse has a unit number of P + 6 unit widths, the binary number 0001 (hexadecimal number) Wherein the width of the high level pulse is P + 2 unit widths and the width of the low level pulse is P + 5 unit widths, the binary value 0010 (hexadecimal number 2) When the width of the high level pulse is P + 3 unit widths and the width of the low level pulse is composed of P + 4 unit widths, a binary number 0011 (hexadecimal number 3) Level pulse is composed of P + 4 unit widths, and the width of the low level pulse is P + 3 Level pulse has a unit width of P + 5, and the width of the low-level pulse is P + 2 units (unit: Level pulse is composed of P + 6 unit widths, and the width of the low level pulse is P + 1 unit widths Level pulse is composed of P + 7 unit widths, and the width of the low-level pulse is composed of P unit widths (Hexadecimal number 7).

In the reverse combination, when the width of the low level pulse is P unit widths and the width of the high level pulse is composed of P + 7 unit widths, it represents a binary number 1000 (hexadecimal) 8 Level pulse has a unit width of P + 1, and the width of the high-level pulse has a unit number of P + 6 unit widths, a binary number 1001 value (hexadecimal number 9) Level pulse has a unit width of P + 2 and a width of the high-level pulse has a unit width of P + 5, a binary number 1010 (hexadecimal number A) Level pulse is composed of P + 3 unit widths, the width of the high-level pulse is a binary number 1011 (hexadecimal number) when the width of the high level pulse is composed of P + 4 unit widths, Level pulse is composed of P + 4 unit widths, and the width of the high level pulse is P + 3 Level pulse is composed of P + 5 unit widths, and the width of the high-level pulse is P + 2 units (unit: Level pulse is composed of P + 6 unit widths, and the width of the high-level pulse is P + 1 unit widths Level pulse is composed of P + 7 unit widths, and the width of the high-level pulse is composed of P unit widths (Hexadecimal number, F) when it is a binary value.

Using the above-described technology, a smart device (smart phone, smart pad, smart watch, etc.) can be used as an access security authentication means and can be used as a location service means by receiving position data from indoor and outdoor illumination.

As described above, according to the visible light communication method of the present invention, the transmitting device transmits the data for transmission including the visible light signal to the receiving device by using the combination of the width of the high level pulse and the width of the low level pulse, The transmitting device can transmit a large amount of data more quickly.

In addition, when the user has a receiving device having a camera, such as a smart phone, a smart pad, a smart watch, etc., the user can perform the visible light ID and communication using the same, It is possible to easily use visible light communication without purchasing an ID or visible light communication receiver.

1 is a conceptual diagram for explaining a visible light communication method according to an embodiment of the present invention.
2 is a table showing the number of expressible bits according to the number of expandable unit widths in one frame of a visible light signal output from the transmitting device of FIG.
FIGS. 3 to 18 are diagrams for explaining an example of a pulse width combination in one frame of a visible light signal output from the transmitting device of FIG. 1. FIG.
19 is a diagram showing an example of performing position service by receiving position data from indoor and outdoor lighting by the communication method of FIG.
20 is a diagram illustrating an example in which a billing system according to an embodiment of the present invention is used.
FIG. 21 is a conceptual diagram for specifically explaining the payment system of FIG. 20; FIG.
22 is a flowchart for explaining a payment method according to an embodiment of the present invention.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text.

It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprising" or "having ", and the like, are intended to specify the presence of stated features, integers, steps, operations, elements, parts, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

1 is a conceptual diagram for explaining a visible light communication method according to an embodiment of the present invention.

Referring to FIG. 1, the visible light communication method according to the present embodiment relates to a communication method for transmitting a visible light signal from a camera flash of a transmitting device 100 to a photodiode or a camera image sensor of the receiving device 200. The transmitting device 100 and the receiving device 200 may be a smart device having a digital camera such as a smart phone or a tablet PC. The demodulator of the receiver may also be a camera image sensor or a photodiode selectively.

In the visible light communication method according to the present embodiment, first, the camera flash of the transmitting device 100 uses a combination of a width of a high level pulse and a width of a low level pulse in one frame (hereinafter, (Hereinafter referred to as " transmission data ") by including a visible light signal by using a pulse width combination (hereinafter referred to as a 'pulse width combination').

Then, the receiving device 200 can receive the visible light signal through the camera and extract the transmission data.

If the transmitting device 100 is a smart phone driven by an iOS or an Android OS among smart devices, it controls the camera flash in the form of an app, so that time deviates depending on the characteristics of the OS and the performance of the application processor (AP) The OS assigns a time slice to each process, and the average wait time and average turnaround time that occur when switching between the process and the process (context switching) Limit occurs. A new type of line coding is required to minimize the influence of the symbol duration problem caused by the deviation of the on / off timing of the smart device built-in camera flash, as shown in FIG. 2 and below.

2 is a table showing the number of expressible bits according to the number of expandable unit widths in one frame of the visible light signal output from the transmitting device of FIG.

Referring to FIG. 2, the visible light signal emitted from the camera flash of the transmitting device 100 is divided into a plurality of frames, and each of the frames may have M unit widths.

In addition, the width of the high level pulse and the width of the low level pulse may all be composed of at least P consecutive unit widths. At this time, M must be an integer with M > 2 * P. Here, the width of the high-level pulse and the width of the low-level pulse are all configured to be equal to or greater than a minimum of P consecutive unit widths because of the functional limitation of the camera flash of the transmitting device 100.

If the unit width in which the width of the high level pulse or the width of the low level pulse can be expanded to P or more is referred to as an expandable unit width and the number of expandable unit widths is defined as W, ?? 2 * P can be satisfied. At this time, W may be an integer of 1 or more. For example, as shown in FIG. 3, the number W of expandable unit widths may have a value of 1, 3, 7, 15, ..., 2 n -1,. At this time, n may be an integer of 1 or more.

On the other hand, when the number W of expandable unit widths is 2 n -1, the maximum number of bits in which the pulse width combination in one frame can be expressed may be 2 n + 1 . For example, when the number W of expandable units is 1, the maximum number of bits is 4. When the number W of expandable units is 3, the maximum number of bits is 8, When the number of widths (W) is 7, the maximum number of bits may be 16.

FIGS. 3 to 18 are diagrams for explaining an example of a pulse width combination in one frame of a visible light signal output from the transmitting device of FIG. 1. FIG.

3 to 18, the pulse width combination is a forward combination in which the high level pulse precedes and the low level pulse follows, and a reverse combination in which the low level pulse precedes and the high level pulse follows . ≪ / RTI >

Specifically, the forward combination is such that when the width of the high level pulse increases from P unit widths to P + W unit widths, the width of the low level pulse is P + W unit widths And the reverse combination may be a combination in which the width of the low level pulse increases by one unit width from P unit widths to P + W unit widths, May be a combination of decreasing from P + W unit widths to P unit widths one by one. Therefore, when the maximum number of bits in which the pulse width combination can be expressed is 2 n + 1 , the number of bits of the forward combination is 2 n , and the number of bits of the backward combination is 2 n .

The pulse width combination shown in FIGS. 3 to 18 is an example in which the number (W) of expandable unit widths is 7 and the P is 10.

First, the forward combination may be expressed as follows.

3, when the width of the high level pulse is composed of P unit widths and the width of the low level pulse is composed of P + 7 unit widths, a binary number 0000 value (hexadecimal number: 0) Lt; / RTI >

As shown in FIG. 4, when the width of the high level pulse is P + 1 unit widths and the width of the low level pulse is composed of P + 6 unit widths, a binary 0001 value (hexadecimal number; 1)

As shown in FIG. 5, when the width of the high level pulse is P + 2 unit widths and the width of the low level pulse is composed of P + 5 unit widths, a binary value 0010 (hexadecimal number; 2), < / RTI >

As shown in FIG. 6, when the width of the high level pulse is P + 3 unit widths and the width of the low level pulse is P + 4 unit widths, the binary number 0011 (hexadecimal number; 3)

As shown in FIG. 7, when the width of the high level pulse is P + 4 unit widths and the width of the low level pulse is composed of P + 3 unit widths, the binary 0100 value (hexadecimal number; 4)

As shown in FIG. 8, when the width of the high level pulse is made up of P + 5 unit widths and the width of the low level pulse is made up of P + 2 unit widths, a binary 0101 value (hexadecimal number; 5)

As shown in FIG. 9, when the width of the high level pulse is composed of P + 6 unit widths and the width of the low level pulse is composed of P + 1 unit widths, a binary 0110 value (hexadecimal number; 6)

As shown in FIG. 10, when the width of the high-level pulse is made up of P + 7 unit widths and the width of the low-level pulse is made up of P unit widths, a binary 0111 value (hexadecimal) Lt; / RTI >

Then, the reverse combination may be expressed as follows.

11, when the width of the low level pulse is composed of P unit widths and the width of the high level pulse is composed of P + 7 unit widths, a binary 1000 value (hexadecimal) Lt; / RTI >

As shown in FIG. 12, when the width of the low level pulse is P + 1 unit widths and the width of the high level pulse is composed of P + 6 unit widths, a value of binary number 1001 (hexadecimal number; 9)

As shown in FIG. 13, when the width of the low level pulse is P + 2 unit widths and the width of the high level pulse is composed of P + 5 unit widths, a binary 1010 value (hexadecimal number; A), < / RTI >

14, when the width of the low level pulse is made up of P + 3 unit widths and the width of the high level pulse is made up of P + 4 unit widths, a binary number 1011 value (hexadecimal number; B)

As shown in FIG. 15, when the width of the low level pulse is made up of P + 4 unit widths and the width of the high level pulse is made up of P + 3 unit widths, a binary number 1100 value (hexadecimal number; C)

As shown in FIG. 16, when the width of the low level pulse is made up of P + 5 unit widths and the width of the high level pulse is made up of P + 2 unit widths, the binary number 1101 value (hexadecimal number; D)

As shown in FIG. 17, when the width of the low level pulse is P + 6 unit widths and the width of the high level pulse is composed of P + 1 unit widths, a binary 0110 value (hexadecimal number; E)

As shown in FIG. 18, when the width of the low level pulse is composed of P + 7 unit widths and the width of the high level pulse is composed of P unit widths, a binary 0111 value (hexadecimal) ≪ / RTI >

As described above, according to the visible light communication method of the present embodiment, the camera flash of the transmission device 100 includes a combination of the width of the high level pulse and the width of the low level pulse, The transmitting device 100 can transmit a large amount of data more quickly by transmitting the image data to the camera image sensor of the receiving device 200.

In addition, when the user has the receiving device 200 having the camera, for example, a smart phone, a smart pad, a smart watch, etc., the user can perform visible light communication using the same, It is possible to easily use visible light communication without purchasing a visible light communication receiver of the present invention.

FIG. 19 is a diagram showing an example of performing position service by receiving position data from indoor and outdoor lighting by the communication method of FIG. 1;

Referring to FIG. 19, when the transmitting device 100 is an indoor lighting system and the receiving device 200 is a smart device having a camera, the receiving device receives the visible light signal from the lighting system The location service can be performed by receiving the data.

Meanwhile, the communication method described above can be utilized as an access security authentication method for a smart device (smart phone, smart pad, smart watch, etc.).

Such a communication method can also be utilized as a payment method.

FIG. 20 is a diagram illustrating an example in which a payment system according to an embodiment of the present invention is used, and FIG. 21 is a conceptual diagram for explaining a payment system of FIG. 20 in detail.

20 and 21, the payment system according to the present embodiment may include a smart terminal and a payment terminal. At this time, the smart terminal assigns the same reference numeral as the transmitting device 100 as an example of the transmitting device 100, and the payment terminal receives the receiving device 200 as an example of the receiving device 200 200 will be given the same reference numerals.

The smart terminal 100 may output a Near Field Communication (NFC) signal and a Visible Light Communication (VLC) signal. Here, the VLC signal may be a signal using the communication method described above.

The smart terminal 100 includes an NFC transmission unit 110 capable of outputting the NFC signal, a VLC transmission unit 120 capable of outputting the VLC signal, and an NFC transmission unit 110 and a VLC transmission unit And a terminal controller 130 for controlling the terminal 120.

In addition, the smart terminal 100 may further include an NFC receiver (not shown) capable of receiving an external NFC signal and a VLC receiver (not shown) capable of receiving an external VLC signal. At this time, the terminal control unit 130 may also control the NFC receiver and the VLC receiver.

The smart terminal 100 may be a smart phone or a tablet PC, and may include a camera capable of performing the functions of the VLC transmitter 120 and the VLC receiver. That is, the VLC transmitter 120 may be a camera flash capable of outputting the VLC signal, and the VLC receiver may be a camera image sensor capable of receiving an external VLC signal.

The payment terminal 200 can receive the NFC signal and the VLC signal from the smart terminal 100 and proceed with the payment by the smart terminal 100 when both the NFC signal and the VLC signal are received .

In detail, the payment terminal 200 includes an NFC receiver 210 capable of receiving the NFC signal, a VLC receiver 220 receiving the VLC signal, and a receiver 220 receiving both the NFC signal and the VLC signal And a settlement progress unit 230 for proceeding settlement by the smart terminal 100. [

The payment terminal 200 may include an NFC transmitter (not shown) capable of transmitting an external NFC signal and a VLC transmitter (not shown) capable of transmitting an external VLC signal. At this time, the settlement progress unit 230 may also control the NFC transmitting apparatus and the VLC transmitting apparatus.

In this embodiment, when the VLC signal is received after the NFC signal is received, the payment progress unit 230 may proceed with the settlement by the smart terminal 100. [ Alternatively, when the NFC signal is received after the VLC signal is received, the payment progress unit 230 may proceed with the settlement by the smart terminal.

Meanwhile, the payment terminal 200 may be installed in various devices and operated. For example, the payment terminal 200 may be installed in a transportation means such as a bus, a subway, a taxi, or the like, or may be installed in a vending machine for purchasing various tables and selling various goods. In Fig. 1, an example is shown in which a vending machine is installed.

Hereinafter, a payment method using the payment system will be described in detail using a separate drawing.

22 is a flowchart for explaining a payment method according to an embodiment of the present invention.

20 to 22, in the payment method according to the present embodiment, the smart terminal 100 first transmits a Near Field Communication (NFC) signal to the payment terminal 200 (S100) . For example, the NFC transmitter 110 may generate the NFC signal and transmit the NFC signal to the NFC receiver 210.

Then, the smart terminal 100 transmits a Visible Light Communication (VLC) signal to the payment terminal 200 (S200). For example, the VLC transmitter 120 may generate the VLC signal and transmit the VLC signal to the NFC receiver 220.

Meanwhile, the step S200 of transmitting the VLC signal may be performed after the step S100 of transmitting the NFC signal. Alternatively, the step S100 of transmitting the NFC signal may be performed after the step 200 of transmitting the VLC signal.

Then, when the payment terminal 200 receives both the NFC signal and the VLC signal, the settlement by the smart terminal 100 proceeds (S300). For example, when the payment progress unit 230 receives the NFC signal from the NFC receiver 210 and receives the VLC signal from the VLC receiver 220, You can proceed.

As described above, according to the present embodiment, when the payment terminal 200 receives the NFC signal and the VLC signal and proceeds with the settlement by the smart terminal 100, The safety can be further improved. That is, when the smart terminal 100 further connects to the payment terminal 200 by further using the VLC having enhanced security than the NFC, the security and stability according to the payment progress can be further improved.

While the present invention has been described in connection with what is presently considered to be practical and exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: transmitting device 200: receiving device

Claims (10)

A visible light communication method for transmitting a signal from a camera flash of a transmitting device to a photodiode of the receiving device or a camera image sensor,
The camera flash of the transmitting device uses a combination of a width of a high level pulse and a width of a low level pulse within one frame (hereinafter referred to as a 'pulse width combination') to transmit (Hereinafter referred to as " transmission data ") including a visible light signal; And
The receiving device receiving the visible light signal through the camera and extracting the transmission data,
Wherein the frame consists of M unit widths, wherein the width of the high level pulse and the width of the low level pulse are all comprised of at least P consecutive unit widths, where M is M > 2 * P And P is an integer of 1 or more),
The width of the high level pulse or the width of the low level pulse can be expanded to P or more, and the number of the expandable unit widths is W, then W = M - 2 * P (where W is an integer of 1 or more),
Wherein the number W of expandable unit widths has a value of 1, 3, 7, 15, ..., 2 n -1, ... (where n is an integer of 1 or more)
When the number W of expandable unit widths is 2 n -1, the maximum number of bits in which the pulse width combination in the one frame can be expressed is 2 n + 1 ,
Wherein the pulse width combination comprises a forward combination in which the high level pulse precedes and the low level pulse precedes and a reverse combination in which the low level pulse precedes and the high level pulse follows,
The forward combination is such that when the width of the high level pulse increases from P unit widths to P + W unit widths, the width of the low level pulse is P unit widths in P + W unit widths, Lt; RTI ID = 0.0 > 1 < / RTI &
The reverse combination is such that when the width of the low level pulse increases from P unit widths to P + W unit widths, the width of the high level pulse is P unit widths in P + W unit widths, Is reduced by one by one. delete delete delete delete delete delete The visible light communication method according to claim 1, wherein the number (W) of expandable unit widths is 7. 9. The method of claim 8,
When the width of the high level pulse is P unit widths and the width of the low level pulse is composed of P + 7 unit widths, a binary number 0000 value (hexadecimal number 0)
Wherein the width of the high level pulse is P + 1 unit widths and the width of the low level pulse is a unit number of P + 6 unit widths, the binary 0001 value (hexadecimal number)
When the width of the high level pulse is P + 2 unit widths and the width of the low level pulse is P + 5 unit widths, a binary value 0010 (hexadecimal number 2)
Level pulse has a unit width of P + 3, and the width of the low-level pulse has a unit width of P + 4, and represents a binary number 0011 (hexadecimal number 3)
When the width of the high level pulse is P + 4 unit widths and the width of the low level pulse is composed of P + 3 unit widths, a binary 0100 value (hexadecimal number 4)
When the width of the high level pulse is constituted by P + 5 unit widths and the width of the low level pulse is constituted by P + 2 unit widths, a binary number 0101 value (hexadecimal number: 5)
When the width of the high level pulse is P + 6 unit widths and the width of the low level pulse is P + 1 unit widths, a binary 0110 value (hexadecimal number 6)
When the width of the high level pulse is made up of P + 7 unit widths and the width of the low level pulse is made up of P unit widths, the combination is a combination showing a binary 0111 value (hexadecimal number 7) And a visible light communication method. 10. The method of claim 9,
Wherein when the width of the low level pulse is P unit widths and the width of the high level pulse is composed of P + 7 unit widths, a binary number 1000 value (hexadecimal number 8)
The width of the low level pulse is P + 1 unit widths and the width of the high level pulse is a P + 6 unit widths, which represents a binary number 1001 value (hexadecimal number 9)
Wherein the width of the low level pulse is P + 2 unit widths, and the width of the high level pulse comprises a unit width of P + 5, and represents a binary number 1010 value (hexadecimal number A)
The width of the low level pulse is P + 3 unit widths, and the width of the high level pulse is a binary number 1011 (hexadecimal number) when the width of the high level pulse is P + 4 unit widths,
Wherein the width of the low level pulse is P + 4 unit widths, and the width of the high level pulse is a P + 3 unit widths, the binary level 1100 value (hexadecimal)
When the width of the low level pulse is P + 5 unit widths and the width of the high level pulse is composed of P + 2 unit widths, a binary 1101 value (hexadecimal)
Wherein the width of the low level pulse is P + 6 unit widths and the width of the high level pulse is a binary number 0110 value (hexadecimal number E) when the width of the high level pulse is P + 1 unit widths,
Level pulses are constituted by P + 7 unit widths, and when the width of the high-level pulses is constituted by P unit widths, the combination is a combination representing a binary 0111 value (hexadecimal number F) And a visible light communication method.
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