CN108092713B - Indoor communication modulation device, communication method and system based on sunlight source - Google Patents
Indoor communication modulation device, communication method and system based on sunlight source Download PDFInfo
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Abstract
一种基于日光光源的室内通信调制装置、通信方法及系统。本发明先通过顺序连接的电压信号模块、电极和电光效应模块，将待传输数据根据设置的调制深度和偏置生成电压信号，然后将所述电压信号施加于电光效应模块，通过所述电光效应模块对射入室内的日光，或对室内照明光源进行调制。由接收装置端的光敏器件、跨阻放大器和信号处理模块接收处理。由于本发明所提供的方案能够通过设置于门窗上的电光效应模块直接对射入室内的自然光进行调制，因此，可直接将日光用于室内通信，从而在智能调节室内照明的同时，把现有无线可见光通信方案中作为底噪的日光变成通信光源利用起来，从而提升了通信效率。本发明能与现有无线可见光通信方案兼容。
An indoor communication modulation device, communication method and system based on sunlight light source. In the present invention, the voltage signal module, the electrode and the electro-optical effect module are connected in sequence to generate the voltage signal according to the set modulation depth and offset of the data to be transmitted, and then the voltage signal is applied to the electro-optical effect module, through the electro-optical effect The module modulates the sunlight entering the room, or modulates the indoor lighting source. It is received and processed by a photosensitive device, a transimpedance amplifier and a signal processing module at the receiving end. Since the solution provided by the present invention can directly modulate the natural light injected into the room through the electro-optical effect module arranged on the doors and windows, the sunlight can be directly used for indoor communication, so that the existing indoor lighting can be adjusted intelligently, and the existing In the wireless visible light communication scheme, sunlight, which is the noise floor, is used as a communication light source, thereby improving communication efficiency. The present invention is compatible with the existing wireless visible light communication scheme.
Description
Technical Field
The invention relates to a visible light communication technology, in particular to a method and a system for realizing indoor communication by directly utilizing sunlight.
Background
Currently, indoor visible light communication is generally implemented based on LED light sources. According to the scheme, the indoor wireless communication is realized by modulating the LED illumination light source. However, because the indoor light source is complicated, especially the frequency band of the sunlight emitted by the window overlaps with the communication frequency band of the LED, the indoor visible light communication based on the LED has disadvantages of signal degradation (large bottom noise), energy waste (a good-lighting room is not necessary to be lighted) and the like under the sunlight.
LED light sources are generally rarely used as the only indoor light source in view of indoor lighting needs and user habits. Therefore, the background noise problem of the existing indoor communication method based on the LED light source is difficult to solve. Therefore, higher performance requirements are put on the visible light communication system including modules for modulation, reception, demodulation and the like, and the optical communication application is limited.
Therefore, a communication scheme capable of effectively modulating an optical signal while satisfying indoor lighting is urgently needed at present, so as to solve the problem of high noise in the white sky of indoor wireless visible light communication.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide an indoor communication modulation device, a communication method and a system based on a sunlight source, which are used for solving the problems of high visible light communication background noise and unsatisfactory communication efficiency in a sunlight-rich environment.
Firstly, in order to achieve the purpose, an indoor visible light communication method based on a sunlight source is provided, and comprises a modulation stage and a receiving stage; the electro-optic effect material used in the modulation stage is a thin film which is paved on the surface of a door or window;
wherein the modulation stage specifically comprises the following steps:
firstly, setting modulation depth and bias;
secondly, generating a voltage signal by the data to be transmitted according to the modulation depth and the bias;
and thirdly, applying the voltage signal to an electro-optic effect material, and modulating the sunlight emitted into the room from the surface of the door and window through the electro-optic effect material. The electro-optical effect material is arranged into a film and can be paved on the surface of a light source in a room so as to modulate all the illumination light sources in the room and intelligently adjust the illumination intensity.
Further, in the above method, the receiving step includes: and receiving the modulated optical signal, converting the optical signal into an electrical signal, and amplifying and processing the electrical signal.
Furthermore, in the method, the modulation depth and the offset are dynamically adjusted in real time according to the illumination intensity of the sunlight entering the room.
Secondly, in order to achieve the above object, an indoor visible light modulation device based on a sunlight light source is also provided, which comprises a voltage signal module, an electrode and an electro-optical effect module which are connected in sequence:
the output end of the voltage signal module is connected with the electrode, and the voltage signal module is used for converting data to be transmitted into a voltage signal according to the modulation depth and the bias requirement and outputting the voltage signal to the electrode;
the electrode is connected with the electro-optical effect module and used for controlling the optical characteristics of the electro-optical effect module according to the voltage signal;
the electro-optical effect module is tiled on the surface of a door or a window or on the surface of an indoor light source, and the electro-optical effect module is used for responding to the voltage signal output by the electrode, the door or the window injects indoor sunlight to modulate, or, on the same principle, utilizes the electro-optical effect module to respond to the voltage signal output by the electrode is right the indoor light source modulates.
Further, in the above-mentioned modulation device, the electro-optical effect module includes a multilayer film structure that is tiled on the surface of a door or a window or on the surface of an indoor light source, and the multilayer film structure includes a polarizer layer, a KDP crystal layer, and an analyzer layer that are sequentially stacked; the polarization directions of the polarizer layer and the analyzer layer are the same; the KDP crystal layer is a KDP crystal layer with the same thickness, the KDP crystal layer is designed to enable light waves with specific wavelengths to be delustered, and the KDP crystal layer is arranged between the polarizer layer and the analyzer layer in a stacked mode.
In parallel with the above solution, the electro-optical effect module may also adopt the following solution: the electro-optical effect module is a graphene film which is paved on the surface of a door or a window or the surface of an indoor light source, one side of the graphene film is connected with the electrode, and the opposite side of the graphene film is grounded through an insulating material.
Further, in the above-described modulation device, the electrode is made of a metal material having high electrical conductivity and low contact resistance with the graphene.
Furthermore, the above-mentioned modulation apparatus further comprises an illumination intensity sensing module, which is disposed indoors and connected to the voltage signal module, and is configured to dynamically adjust the modulation depth and the offset of the voltage signal module according to the indoor illumination intensity. The invention can realize intelligent regulation and control of the indoor illumination light intensity.
Based on the modulation device, the invention also provides an indoor visible light communication system, which comprises the indoor sunlight communication modulation device and a receiving device, wherein the receiving device comprises a photosensitive device, a transimpedance amplifier and a signal processing module which are sequentially cascaded:
the photosensitive device is arranged at the front end of the receiving device and used for receiving the sunlight emitted into the room by the door and the window or the optical signal of the indoor light source after being modulated by the electro-optical effect module and converting the optical signal into an electric signal;
the trans-impedance amplifier is connected between the photosensitive device and the signal processing module and used for amplifying the electric signal and outputting the electric signal to the signal processing unit;
the signal processing module is used for processing the electric signal amplified by the trans-impedance amplifier.
Further, in the above indoor visible light communication system, for the KDP scheme, that is, the KDP crystal layer is used in the indoor sunlight communication modulation apparatus to construct the electro-optical effect module: then, the receiving device further comprises an optical filter; the optical filter is arranged at the front end of the photosensitive device, and the transmission waveband of the optical filter is in accordance with the extinction waveband of the KDP crystal;
advantageous effects
In the invention, at the receiving device end, the modulated optical signal is received through the photosensitive device, the trans-impedance amplifier and the signal processing module, the optical signal is converted into an electric signal, and the electric signal is amplified and processed. The scheme provided by the invention can directly modulate the natural light emitted into the room through the electro-optical effect module on the door and the window, so that the sunlight can be directly used for indoor communication, the indoor visible light illumination is ensured, and meanwhile, the sunlight component which is taken as the background noise in the existing wireless visible light communication scheme is utilized, so that the communication efficiency is higher. Because the original bottom noise is used for communication, the signal-to-noise ratio of a receiving end is greatly improved, and the performance requirements of each module of a communication system including modulation, receiving, demodulation and the like can be properly reduced.
Meanwhile, the modulation scheme provided by the invention has higher response frequency. The reason for this is that; the existing wireless visible light communication scheme usually adopts LED lamp internal modulation, the response frequency of an LED product under the current technical condition is not high, and the upper limit of a carrier wave is generally dozens of megahertz. The response frequency of the KDP crystal in the field of wired optical communication can reach ten gigahertz, and tests show that the response frequency of the graphene can also reach gigahertz. In view of this, the present invention may use a data transmission rate of a hundred mega-level or more for the electro-optical effect module constructed by the KDP crystal layer or the graphene film, or use carrier communication of a frequency carrier of a hundred mega-level or more for the electro-optical effect module constructed by the KDP crystal layer or the graphene film. Therefore, on one hand, the data transmission rate of indoor optical communication can be greatly improved; on the other hand, an optical signal modulated by the electro-optical effect module and constructed by the KDP crystal layer or the graphene film can be separated from an optical signal modulated by the LED on the frequency spectrum, low-pass (aiming at the LED signal) and high-pass (aiming at the modulation signal of the invention) filtering is further carried out on the receiving end aiming at the received waveform respectively, the two modulation signals can be prevented from mutual interference, and therefore the wireless visible light communication system is compatible with the existing wireless visible light communication scheme, and the two modulation signals can run in parallel and independently without mutual influence.
Furthermore, the function of intelligent glass can be considered in the scheme, the current indoor lighting condition is fed back by additionally arranging the illumination intensity sensing module or multiplexing the photosensitive device of the receiving device, so that reasonable bias is set, and indoor lighting is maintained in a comfortable state.
Meanwhile, based on the existing electro-optic effect material, the invention provides two schemes, which realize that the light wave is used as the carrier of the information, the communication signal is expressed on the intensity of the light (or the characteristics of phase frequency and the like can be considered) through two specific modulation schemes, then the information is received by the light sensor, and the light wave carrying the information is transmitted in the dispersion space.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart of an indoor visible light communication method based on a daylight source according to the present invention;
FIG. 2 is a schematic diagram of an indoor visible light modulation device implemented using a KDP crystal;
FIG. 3 is a schematic diagram of an indoor visible light modulation device implemented using graphene thin films;
FIG. 4 is a graph showing the relationship between the transmittance of graphene and the applied voltage;
FIG. 5 is a schematic diagram of the connection relationship between electrodes and graphene layers when the graphene film is used in an electro-optic effect module;
fig. 6 is a block diagram of an indoor visible light communication system according to the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
To meet indoor communication requirements, the electro-optic response rate of the optical modulator needs to be sufficiently high. If 1MBaud/s is to be achieved, the total response time of the single electro-optic effect of the modulator (rise edge time + fall edge time) is required to be less than 1 μ s (i.e. at least 10^6 "rise then fall" operations can occur per second). At present, the response time in the field of intelligent glass research is basically more than ms, obviously, the communication requirement cannot be met, and therefore, an electro-optical material with high response rate (namely, faster response to voltage change and shorter total response time) is required to be searched
The scheme adopts the material with the electro-optical effect to manufacture a film (as an electro-optical effect module) to be attached to the surfaces of light-transmitting doors and windows made of glass and other materials. The material may exhibit different optical properties (e.g., transmittance, frequency distribution of transmitted light intensity, etc.) at different voltages. When outdoor natural light penetrates through the light modulation film to enter a room, the natural light is modulated by the film under the control of a voltage signal, and the change of frequency spectrum distribution or the change of illumination intensity occurs. The modulated optical signal is restored through the receiving device, and information carried in the modulated optical signal can be obtained, so that communication is realized.
It is generally believed that when the rate of light change exceeds 60Hz, the change is not observable by the human eye. The modulation frequency for communication is far higher than 60Hz, so that the light modulation by adopting the method does not cause flicker and does not influence the illumination effect.
The electrical signal changes in the communication are often based on some reference voltage, i.e. bias. We generally understand a signal as having data to be a set voltage value and no data to be 0. However, in visible light communication, for illumination effect, it is often necessary to ensure a certain illumination intensity when there is no data, i.e. to set a reasonable bias (i.e. to set a voltage corresponding to no signal). By setting the appropriate bias and modulation depth (i.e., the magnitude of the voltage change in the presence of a signal), the average transmitted light intensity can be maintained at a suitable value within the allowable adjustment range for the outdoor light intensity, thereby optimizing indoor lighting or minimizing adverse effects on lighting.
Fig. 1 is a method for indoor visible light communication based on a daylight light source according to the present invention, which includes two parts, a modulation phase and a receiving phase; the electro-optic effect material used in the modulation stage is a thin film which is paved on the surface of a door or window;
the modulation phase comprises the following steps:
firstly, setting modulation depth and bias;
secondly, generating a voltage signal by the data to be transmitted according to the modulation depth and the bias;
and thirdly, applying the voltage signal to an electro-optic effect material, and modulating the sunlight emitted into the room from the surface of the door and window through the electro-optic effect material. The electro-optical effect material is arranged into a film and can be paved on the surface of a light source in a room so as to modulate all the illumination light sources in the room and intelligently adjust the illumination intensity.
Further, in the above method, the receiving step includes: and receiving the modulated optical signal, converting the optical signal into an electrical signal, and amplifying and processing the electrical signal.
Furthermore, in the method, the modulation depth and the offset are dynamically adjusted in real time according to the illumination intensity of the sunlight entering the room.
Secondly, referring to fig. 2, in order to achieve the above object, there is also provided an indoor visible light modulation device based on a sunlight light source, comprising a voltage signal module, an electrode and an electro-optical effect module which are connected in sequence:
the output end of the voltage signal module is connected with the electrode, and the voltage signal module is used for converting data to be transmitted into a voltage signal according to the modulation depth and the bias requirement and outputting the voltage signal to the electrode;
the electrode is connected with the electro-optical effect module and used for controlling the optical characteristics of the electro-optical effect module according to the voltage signal;
the electro-optical effect module is tiled on the surface of a door or a window or on the surface of an indoor light source, and the electro-optical effect module is used for responding to the voltage signal output by the electrode, the door or the window injects indoor sunlight to modulate, or, on the same principle, utilizes the electro-optical effect module to respond to the voltage signal output by the electrode is right the indoor light source modulates.
Further, in the above-mentioned modulation device, the electro-optical effect module includes a multilayer film structure that is tiled on the surface of a door or a window or on the surface of an indoor light source, and the multilayer film structure includes a polarizer layer, a KDP crystal layer, and an analyzer layer that are sequentially stacked; the polarization directions of the polarizer layer and the analyzer layer are the same; the KDP crystal layer is a KDP crystal layer with the same thickness, the KDP crystal layer is designed to enable light waves with specific wavelengths to be delustered, and the KDP crystal layer is arranged between the polarizer layer and the analyzer layer in a stacked mode.
The KDP crystal is a crystal with linear electro-optic effect, and a slice of the KDP crystal in the direction vertical to an optical axis is selected to be made into a thin film material which is paved on the surface of a door or a window or the surface of an indoor light source, so that the material has the following characteristics:
for common KDP crystals, there is nx＝ny＝no，nz＝ne(wherein, nxIs the refractive index in the x direction, nyThe refractive index in the y direction, which is equal to the normal or o-light refractive index noEqual; refractive index n in z directionznz
Is the extraordinary refractive index or the e-optic refractive index) which is generally used as a basis for analyzing the crystal; when the z-axis external strength of the KDP crystal is EzThe uniaxial crystal becomes a biaxial crystal, and an x 'axis (fast axis) and a y' axis (slow axis) are formed in an x-y plane:
wherein gamma is63Is a linear electro-optic coefficient and is determined by the crystal properties.
The natural light is unpolarized light which is uniformly distributed in each vibration direction, for the convenience of analysis, a polar coordinate system is established by taking the x 'axis as the polar axis, and by taking the first polaroid and the x' axis as an example to form an included angle of 45 degrees, the light wave which penetrates through the polaroid and reaches the surface of the KDP crystal can be expressed as
Wherein A is the amplitude of the light,
(where λ is the wavelength of the light wave and c is the speed of light in vacuum) is the circular frequency of the light,
to reach the initial phase at the entrance face of the crystal.
The light wave is incident along the crystal z-axis, and then the light wave is orthogonally decomposed into x' -axis components when passing through the KDP crystal
And component of y
Then both components pass through thickA KDP crystal film with a degree of L is formed later
The phase difference of (a); when a voltage in the z direction is applied
In the meantime, a phase difference of pi is caused to light with a wavelength of λ, and since sunlight has a certain time continuity, light with a wavelength of λ (i.e., an extinction band of the KDP crystal) disappears, and at the same time, light waves with nearby wavelengths are significantly attenuated centering on λ.
Here, the first polarizer can filter out the light wave having the vibration direction from the natural light, and the advantage of transmitting only the light wave having the vibration direction is that: the vibration of the polarized light in the crystal can be orthogonally decomposed into two equal components; a second polarizer can combine two orthogonal vibration components together so that transmitted light of wavelength λ is weaker (extinguished) in the presence of a voltage and half the incident intensity in the absence of a voltage;
by the modulation mode, the film expresses an electric signal carrying data on the parameter of the light intensity of the transmitted light with a specific wave band according to the voltage signal on the electrode. Through the optical filter with the wavelength selective transmission function, the photoelectric current can be captured by the small-visual-angle PIN tube and generated so as to be received by the receiving end.
The scheme is characterized in that:
in terms of communication: the response rate of the scheme exceeds that of the existing LED, the indoor communication requirement is met, and the potential that the transmission rate exceeds that of the LED is achieved.
In the aspect of lighting: the transmission light intensity mean value of this scheme is less than 50%, can protect daylighting through the mode of rationally arranging printing opacity district and communication area, nevertheless must have the influence to daylighting, can make indoor light suitably become soft when external light is stronger, can be unfavorable to daylighting when external light is not strong enough.
In the aspect of devices: it is considered that the visible light obtained by the modulation of the present invention is not substantially different from the visible light used in the existing wireless visible light communication. The receiving device in the scheme can directly use the existing optical receiver scheme, namely, the PIN-TIA scheme: the light is sensed by a Photodiode (PIN), and then the signal passes through a transimpedance amplifier (TIA), an operational amplifier and a wave shaping circuit and enters hardware with a signal processing function, such as an FPGA. Thereby identifying the information carried in the optical signal. However, the scheme has a special requirement on the receiving device, namely the visual angle of the PIN-TIA receiver is required to be smaller, and meanwhile, the PIN-TIA receiver can play a better communication effect only if the PIN-TIA receiver has an exact receiving direction.
In parallel with the above solution, referring to fig. 3, the electro-optical effect module may also adopt the following solution: the electro-optical effect module is a graphene film which is paved on the surface of a door or a window or the surface of an indoor light source, one side of the graphene film is connected with the electrode, and the opposite side of the graphene film is fixed through an insulating material. Here, the opposite side of the graphene material is grounded to the ground terminal of the signal through the insulating material, so that the signal can be more stable.
The scheme is based on a phenomenon of graphene materials (refer to fig. 4), namely that the Fermi level of graphene can be changed by applying voltage to the graphene. When strong negative voltage is applied to the graphene material, no redundant electrons can generate interband transition due to the accumulation of a large amount of positive charges, and the graphene is transparent to light and does not absorb the electrons; when a strong positive voltage is applied to the graphene material, all electronic states are filled, and interband transition cannot occur, so that absorption does not occur. When the voltage is in a certain range between the two, the fermi level of the graphene is close to the dirac point, and light absorption occurs. The specific parameters are closely related to the preparation process and volume of the graphene material and the electrode material, and cannot be calculated widely.
This scheme expands graphite alkene layer, and the tiling is on door and window surface or the tiling is on indoor light source surface, and electrode material is connected to one side on graphite alkene layer, and the substrate that insulating material constitutes is connected to the opposite side, ground connection. The electrode material is made of materials with good electrical conductivity and small contact resistance with graphene, such as gold and platinum metals; the substrate is mostly made of aluminum oxide and is grounded; the two are matched for applying voltage to the graphene.
The multilayer graphene is made into a film and attached to the surface of glass, and electrodes are arranged and connected by using a structure similar to that shown in fig. 5. The Fermi energy level is changed by using voltage, so that the absorption effect of graphene on light is influenced, a voltage signal is expressed in the intensity of transmitted light, and the voltage signal is received by PIN to form photocurrent which is then delivered to a rear processing circuit.
The scheme is characterized in that:
in the aspect of communication: because the graphene material has high carrier mobility, high voltage response speed and extremely high modulation potential, more signals can be carried in unit time in principle, and the graphene material is suitable for a plurality of materials which can be used for dimming films.
In the aspect of devices: considering that a crystalline material has optical anisotropy, it tends to have a large degree of change in the property of transmitting light when the angle of light irradiation with respect to the optical axis is changed. Therefore, when the crystal is used, the angles of incident light and emergent light are limited, and the effect of too much deviation from modulation is greatly reduced. Therefore, compared to the implementation scheme of the KDP crystal, the graphene as an amorphous material has much smaller angle limitation on incident light and emergent light than a crystal. The graphene is used for visible light modulation, so that the requirement on the directivity of a receiver is greatly reduced, and the light with a wider range of incidence angles can be modulated.
In the aspect of lighting: because the graphene material does not need to be biased and does not need to filter the illumination intensity in the non-polarization direction like a KDP crystal, the graphene scheme is adopted, and as long as the bias voltage and the modulation depth are reasonably set, the transmissivity of outdoor light intensity can be maintained at any numerical value in a large range (close to 0 to close to 100 percent), and two targets of communication and indoor light intensity adjustment can be perfectly considered.
Further, in the above-described modulation device, the electrode is made of a material having high conductivity and low contact resistance with graphene, and a gold electrode or a platinum electrode is often used.
Furthermore, the above adjusting device further includes an illumination intensity sensing module, where the illumination intensity sensing module is required to be located at a position in communication with the film, for example, the illumination intensity sensing module is located in the room and near the film, and is connected to the voltage signal module, so as to dynamically adjust the modulation depth and the offset of the voltage signal module according to the indoor illumination intensity, thereby implementing intelligent adjustment and control of the indoor illumination light intensity.
Based on the modulation device, the present invention also provides the indoor visible light communication system as shown in fig. 6, which includes the indoor daylight communication modulation device and a receiving device, wherein the receiving device includes a sequentially cascaded photosensor (e.g., PIN tube), trans-impedance amplifier (TIA), and signal processing module (e.g., FPGA module):
the photosensitive device is arranged at the front end of the receiving device and used for receiving the sunlight emitted into the room by the door and the window or the optical signal of the indoor light source after being modulated by the electro-optical effect module and converting the optical signal into an electric signal (specifically, a current signal);
the trans-impedance amplifier is connected between the photosensitive device and the signal processing module and is used for amplifying the electric (current) signal into a voltage signal and outputting the voltage signal to the signal processing unit for signal processing;
the signal processing module is used for processing the electric signal amplified by the trans-impedance amplifier.
Further, in the above indoor visible light communication system, for a KDP scheme, that is, a KDP crystal layer is used in the indoor sunlight communication modulation apparatus to construct the electro-optical effect module: then, the receiving device further comprises an optical filter; the optical filter is arranged at the front end of the photosensitive device, and the transmission waveband of the optical filter is in accordance with the extinction waveband of the KDP crystal.
In general, this scheme and the indoor wireless visible light communication scheme based on LED will not be used simultaneously, but in order to prevent mutual interference when using simultaneously, there are the following auxiliary schemes:
the existing wireless visible light communication scheme usually adopts LED lamp internal modulation, the response frequency of an LED product under the current technical condition is not high, and the upper limit of a carrier wave is generally dozens of megahertz. The response frequency of the KDP crystal in the field of wired optical communication can reach ten gigahertz, and tests show that the response frequency of the graphene can also reach gigahertz. In view of this, carrier communication using a data transmission rate of the order of hundreds of megabits or more for the dimming film or a carrier wave of the order of hundreds of megabits or more for the dimming film can be performed. Therefore, on one hand, the data transmission rate of indoor optical communication can be greatly improved; on the other hand, the optical signal modulated by the light modulation film and the optical signal modulated by the LED can be separated on the frequency spectrum, and then low-pass (aiming at the LED signal) and high-pass (aiming at the light modulation film) filtering is respectively carried out on the receiving end aiming at the received waveform, so that the two modulation signals can not interfere with each other, the wireless visible light communication system is compatible with the existing wireless visible light communication scheme, and the wireless visible light communication system can run in parallel without mutual influence.
The technical scheme of the invention has the advantages that: the method comprises the steps that firstly, data to be transmitted are generated into voltage signals according to set modulation depth and bias through a voltage signal module, an electrode and an electro-optical effect module which are sequentially connected, then the voltage signals are applied to the electro-optical effect module, sunlight emitted into a room is modulated through the electro-optical effect module, and meanwhile real-time intelligent regulation and control of indoor illumination intensity can be achieved through controlling the electro-optical effect module. At the receiving device end, the modulated optical signals are received through a photosensitive device, a trans-impedance amplifier and a signal processing module, the optical signals are converted into electric signals, and the electric signals are amplified and processed. According to the scheme provided by the invention, natural light emitted into a room can be directly modulated through the electro-optical effect module on the door and the window, so that sunlight can be directly used for indoor communication, and the sunlight used as background noise in the existing wireless visible light communication scheme is changed into a communication light source to be utilized while indoor illumination is intelligently regulated, so that the communication efficiency is improved. The invention can be compatible with the existing wireless visible light communication scheme.
Those of ordinary skill in the art will understand that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An indoor visible light communication method based on a sunlight source comprises a modulation stage and a receiving stage, and is characterized in that an electro-optical effect material used for the modulation stage is a thin film which is paved on the surface of a door window;
wherein the modulation stage comprises:
firstly, setting modulation depth and bias;
secondly, generating a voltage signal according to the modulation depth and the bias for the data to be transmitted,
and thirdly, applying the voltage signal to an electro-optic effect material, and modulating the sunlight emitted into the room from the surface of the door and window through the electro-optic effect material.
2. The daylight source based indoor visible light communication method of claim 1, wherein the receiving phase step comprises:
and receiving the modulated optical signal, converting the optical signal into an electrical signal, and amplifying and processing the electrical signal.
3. The daylight source-based indoor visible light communication method of claim 1, wherein the modulation depth and the offset are dynamically adjusted in real time according to the intensity of daylight illumination entering the room.
4. An indoor visible light modulation device based on a sunlight light source is characterized by comprising a voltage signal module, an electrode and an electro-optical effect module which are sequentially connected;
the output end of the voltage signal module is connected with the electrode, and the voltage signal module is used for converting data to be transmitted into a voltage signal according to the modulation depth and the bias requirement and outputting the voltage signal to the electrode;
the electrode is connected with the electro-optical effect module and used for controlling the optical characteristics of the electro-optical effect module according to the voltage signal;
the electro-optical effect module is tiled on the surface of a door or a window or on the surface of an indoor light source, and the electro-optical effect module is used for responding to a voltage signal output by the electrode and modulating the sunlight emitted into the door or the window or modulating the indoor light source in the same way.
5. The daylight source-based indoor visible light modulation device of claim 4, wherein the electro-optical effect module comprises a multilayer film structure tiled on the surface of a door or window or on the surface of an indoor light source, the multilayer film structure comprises a polarizer layer, a KDP crystal layer and an analyzer layer which are sequentially stacked; the polarization directions of the polarizer layer and the analyzer layer are the same; and the KDP crystal layer has uniform thickness.
6. The indoor visible light modulation device based on the sunlight light source of claim 4 wherein, the electro-optical effect module is a graphene film which is tiled on the surface of a door or window or on the surface of an indoor light source, one side of the graphene film is connected with the electrode, and the opposite side of the graphene film is grounded through an insulating material.
7. The daylight light source-based indoor visible light modulation device according to claim 5 or 6, wherein the electrode is made of a metal material with high electrical conductivity and low contact resistance with graphene.
8. The indoor visible light modulation device based on the daylight light source as claimed in any one of claims 5 or 6, further comprising an illumination intensity sensing module, wherein the illumination intensity sensing module is disposed indoors and connected to the voltage signal module, and is used for dynamically adjusting the modulation depth and the bias of the voltage signal module according to the illumination intensity indoors.
9. An indoor visible light communication system constructed based on the indoor visible light modulation device based on the daylight light source as claimed in claim 8, comprising the indoor daylight communication modulation device and a receiving device, wherein the receiving device comprises a photosensitive device, a transimpedance amplifier and a signal processing module which are sequentially cascaded;
the photosensitive device is arranged at the front end of the receiving device and used for receiving the sunlight emitted into the room by the door and the window or the optical signal of the indoor light source after being modulated by the electro-optical effect module and converting the optical signal into an electric signal;
the trans-impedance amplifier is connected between the photosensitive device and the signal processing module and used for amplifying the electric signal and outputting the electric signal to the signal processing unit;
the signal processing module is used for processing the electric signal amplified by the transimpedance amplifier.
10. The indoor visible light communication system of claim 9, wherein if a KDP crystal layer is used in the indoor solar light communication modulation device to construct the electro-optical effect module, the receiving device further comprises an optical filter;
the optical filter is arranged at the front end of the photosensitive device, and the transmission waveband of the optical filter is consistent with the extinction waveband of the KDP crystal.
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