CN109510664B - Visible light communication device and method - Google Patents
Visible light communication device and method Download PDFInfo
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- CN109510664B CN109510664B CN201811450000.6A CN201811450000A CN109510664B CN 109510664 B CN109510664 B CN 109510664B CN 201811450000 A CN201811450000 A CN 201811450000A CN 109510664 B CN109510664 B CN 109510664B
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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
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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
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/502—LED transmitters
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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
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
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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
- H04B10/60—Receivers
Abstract
The invention provides a visible light communication device and a method, wherein the device comprises an LED emitting module and a visible light receiving module, and the method comprises the following steps: selecting n LED reference points and numbering, loading periodic signals of different time slots in a driving circuit of the LED emission module to modulate emission signals, wherein the LED lamps are fully on as frame headers, and the LED lamps are fully off as frame tails; a photoelectric detector with an optical filter in the visible light receiving module is used for receiving an LED optical signal and completing photoelectric conversion, and a sampling signal is obtained through an amplifier and an analog-to-digital converter and is input to a microprocessor; and acquiring the maximum value of the signal intensity in the sampling signal as a frame header to represent the start of the effective data, and acquiring the minimum value of the signal intensity as a frame tail to represent the end of the effective data to obtain different data frames. The invention rapidly identifies each frame of data, keeps communication synchronization and improves communication efficiency, belonging to the technical field of communication.
Description
Technical Field
The invention belongs to the technical field of communication, and particularly relates to a visible light communication device and method.
Background
Visible light communication is a novel high-speed data transmission technology realized by utilizing light rays of semiconductor illumination. The visible light communication technology loads high-frequency signals which cannot be identified by human eyes to a Light Emitting Diode (LED) for transmission, so that the LED integrates the functions of illumination and communication, is green and low-carbon, can realize nearly zero-energy-consumption communication, can effectively avoid the defects of leakage of radio communication electromagnetic signals and the like, quickly constructs an anti-interference and anti-interception safety information space, and has wide application prospect.
For example, indoor positioning is an important application field of the visible light communication technology, and in order to obtain accurate frame data in the indoor positioning and data transmission processes, a signal sending end and a signal receiving end often need to have a high-precision clock synchronization period, or a time mark needs to be sent while a signal is sent, which affects certain data communication efficiency.
Disclosure of Invention
The invention provides a visible light communication device and a method, which solve the problem of desynchronization of a visible light communication clock, and are convenient for a signal receiving end to quickly and correctly identify each frame of data and keep communication synchronization.
The invention provides a visible light communication device, which comprises at least three LED emission modules and a visible light receiving module, wherein the LED emission modules are in visible light communication connection with the visible light receiving module; the LED transmitting module comprises an LED lamp and a constant current source driving circuit, and the visible light receiving module comprises an optical filter, a photoelectric detector, an amplifier, an analog-to-digital converter and a microprocessor;
the LED transmitting module is used for loading periodic signals of different time slots in the constant current source driving circuit to modulate transmitted signals, n LED reference points are selected and numbered in the transmitted signal modulation process, 1 frame of signals are averagely divided into n +2 time slots, n LED lamps are fully turned on to serve as frame headers, and n LED lamps are fully turned off to serve as frame tails;
the visible light receiving module is used for receiving LED light signals through the photoelectric detector, completing photoelectric conversion, inputting the LED light signals to the analog-to-digital converter through the amplifier, and finally transmitting sampled signals to the microprocessor,
the microprocessor is used for acquiring the maximum value of the signal intensity in the sampling signal as a frame header to represent the start of the effective data, and acquiring the minimum value of the signal intensity as a frame tail to represent the end of the effective data, so as to obtain a complete data frame.
Preferably, in the above apparatus, the LED emitting module turns on only the LED lamp numbered k and turns off the other LED lamps, where k is 1,2, …, n, and the modulated visible light signal rate satisfies a flicker invisible to human eyes.
Preferably, in the above apparatus, the visible light receiving module further includes a timer, the timer controls a signal acquisition interval of the analog-to-digital converter, and a time of the timer is a time slot length of the LED transmitting signal.
Preferably, in the above apparatus, the microprocessor further extracts a signal intensity vector, and determines whether there are n valid data between the frame header and the frame tail, and if there are n valid data, the signal intensity of the photoelectric detector irradiated by the kth LED lamp is obtained by subtracting a frame tail data value from a kth valid data value behind the frame header; otherwise, the effective data is lost, the data processing is abandoned, the visible light receiving module is used again to receive the signal, and the signal intensity vector is extracted again.
The invention also provides a visible light communication method, which comprises the following steps of constructing a visible light communication device, wherein the device comprises at least three LED emitting modules and one visible light receiving module, and the method comprises the following steps:
selecting n LED reference points and numbering, loading periodic signals of different time slots in a driving circuit of the LED emission module to modulate emission signals, averagely dividing 1 frame of signals into n +2 time slots, taking n LED lamps as frame headers when the LED lamps are all on, and taking n LED lamps as frame tails when the LED lamps are all off;
a photoelectric detector with an optical filter in the visible light receiving module is used for receiving an LED optical signal and completing photoelectric conversion, and a sampling signal is obtained through an amplifier and an analog-to-digital converter and is input to a microprocessor;
and acquiring the maximum value of the signal intensity in the sampling signal as a frame header to represent the start of the effective data, and acquiring the minimum value of the signal intensity as a frame tail to represent the end of the effective data to obtain a complete data frame.
Preferably, in the method, the modulating the transmission signal further includes: data k indicates that only the LED with number k is on and the other LEDs are off, where k is 1,2,3, …, n, and the modulated visible light signal rate satisfies the flicker invisible to the human eye.
Preferably, in the above method, in the digital-to-analog converter, the analog-to-digital acquisition interval is controlled by a timer, and the time of the timer is the time slot length of the LED emission signal.
Preferably, in the method, after acquiring the minimum signal strength value as a frame end indicates that the valid data is over, the method further includes: extracting a received signal strength vector; the specific way of extracting the received signal strength vector is as follows: judging whether n effective data exist between the frame head and the frame tail, if the effective data are n, subtracting a frame tail data value from a K effective data value behind the frame head to obtain the signal intensity of the K LED lamp irradiating the photoelectric detector, and obtaining a signal intensity vector of the position of the photoelectric detector; otherwise, the effective data is lost, the data processing is abandoned, and the visible light receiving module is used for receiving the signal again and processing the signal again.
The invention provides a visible light communication device and a method, wherein periodic signals of different time slots are loaded in an LED driving circuit to modulate a transmitting signal, the full brightness of an LED lamp is taken as a frame head at a signal transmitting end, the full extinguishment of the LED lamp is taken as a frame tail, the maximum value of the received signal intensity is taken as the frame head at a signal receiving end, and the minimum value of the received signal intensity is taken as the frame tail, so that each frame of data is correctly identified, the synchronous function of transmitting and receiving data frames is realized, the synchronism of visible light communication is better kept, and the efficiency of the visible light communication is improved.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the technical description of the present invention will be briefly introduced below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor.
FIG. 1 is a schematic structural diagram of a visible light communication device according to the present invention;
FIG. 2 is a schematic flow chart of a visible light communication method provided by the present invention;
FIG. 3 is a schematic diagram of signal modulation for an LED emission module provided in the present invention;
Detailed Description
The invention provides a visible light communication device and a method, which can enable a signal receiving end to quickly and correctly identify each frame of data while transmitting data and keep communication synchronization.
Referring to fig. 1, the present invention provides a visible light communication device, which includes n (n >2) LED emitting modules and a visible light receiving module, wherein the LED emitting modules are connected with the visible light receiving module in visible light communication; the LED transmitting module comprises an LED lamp and a constant current source driving circuit, and the visible light receiving module comprises an optical filter, a photoelectric detector, an amplifier, an analog-to-digital converter and a microprocessor;
the LED transmitting module is used for loading periodic signals of different time slots in the constant current source driving circuit to modulate transmitted signals, n LED reference points are selected and numbered in the transmitted signal modulation process, 1 frame of signals are averagely divided into n +2 time slots, n LED lamps are fully turned on to serve as frame headers, n LED lamps are fully turned off to serve as frame tails, and n is greater than 2;
optionally, in the LED emitting module, data k indicates that only the LED lamp numbered k is turned on, and other LED lamps are turned off, where k is 1,2, …, n, and the modulated visible light signal rate satisfies the flicker invisible to human eyes.
The visible light receiving module is used for receiving an LED light signal through a photoelectric detector, completing photoelectric conversion, inputting the LED light signal to an analog-to-digital converter through an amplifier, and finally transmitting a sampled signal to the microprocessor;
optionally, the visible light receiving module further includes a timer, the timer controls a signal acquisition interval of the analog-to-digital converter, and time of the timer is a time slot length of the LED transmitting signal.
The microprocessor is used for acquiring the maximum value of the signal intensity in the sampling signal as a frame header to represent the start of the effective data, and acquiring the minimum value of the signal intensity as a frame tail to represent the end of the effective data, so as to obtain a complete data frame.
Optionally, the microprocessor further extracts a signal strength vector, and the specific method is as follows: judging whether n effective data exist between the frame head and the frame tail, if the effective data are n, subtracting a frame tail data value from a K effective data value behind the frame head to obtain the signal intensity of the K LED lamp irradiating the photoelectric detector, and obtaining a signal intensity vector of the position of the photoelectric detector; otherwise, the effective data is lost, the data processing is abandoned, the visible light receiving module is used again to receive the signal, and the signal intensity vector is extracted again.
Referring to fig. 2, the present invention further provides a visible light communication method, wherein a visible light communication device is built, and the device includes at least three LED emitting modules and a visible light receiving module; specifically, the LED transmitting module comprises an LED lamp and a constant current source driving circuit, and the visible light receiving module comprises an optical filter, a photoelectric detector, an amplifier, an analog-to-digital converter and a microprocessor.
The method comprises the following steps:
s1, selecting n LED reference points and numbering, loading periodic signals of different time slots in a driving circuit of the LED emission module to modulate emission signals, averagely dividing 1 frame of signals into n +2 time slots, taking n LED lamps as a frame header when the n LED lamps are all on, and taking n LED lamps as a frame tail when the n LED lamps are all off;
optionally, the modulating the transmission signal further includes: data k indicates that only the LED with number k is on and the other LEDs are off, where k is 1,2,3, …, n, and the modulated visible light signal rate satisfies the flicker invisible to the human eye.
Specifically, please refer to fig. 3, fig. 3 is a schematic diagram of signal modulation of the LED emitting module. Firstly, selecting n (n >2) LED reference points and numbering, in the process of signal modulation, equally dividing 1 frame data signals into n +2 time slots, enabling n LED lamps to be fully on as frame headers, enabling the LED lamp with the number of k to be sequentially on in different time slots, and enabling other LED lamps to be off, wherein k is 1,2, and n until the nth lamp is on, and finally, taking the n LED lamps to be fully off as frame tails, so that 1 frame data is sent.
S2, receiving the LED light signal by a photoelectric detector with an optical filter in the visible light receiving module, completing photoelectric conversion, obtaining a sampling signal by an amplifier and an analog-to-digital converter, and inputting the sampling signal to a microprocessor;
optionally, in the digital-to-analog converter, an analog-to-digital acquisition interval is controlled by a timer, and the time of the timer is a time slot length of the LED emission signal.
And S3, acquiring the maximum value of the signal intensity in the sampling signal as a frame header to indicate the start of the effective data, and acquiring the minimum value of the signal intensity as a frame tail to indicate the end of the effective data, thereby obtaining a complete data frame.
Specifically, because the signal transmission uses n LED lamps as a frame header, the intensity of the light signal received by the photodetector is the maximum at this time, n LED lamps are completely extinguished as a frame tail, the intensity of the light signal received by the photodetector is the minimum at this time, and the received light signal is natural light, the maximum value of the signal intensity in the sampling signal can be used as the frame header to indicate the start of the valid data in the visible light receiving module, and the minimum value of the signal intensity can be used as the frame tail to indicate the end of the valid data, so that a frame of data is received and can be distinguished from other frame of data, thereby avoiding data confusion and desynchronization, and maintaining synchronization of signal transmission and reception. In fig. 3, data 1 to data n are light signals emitted from the LED lamps corresponding to numbers 1 to n.
Optionally, after the obtaining the minimum signal strength value as a frame end indicates that the valid data is ended, the method further includes: extracting a received signal strength vector; the specific way of extracting the received signal strength vector is as follows: judging whether n effective data exist between the frame head and the frame tail, if the effective data are n, subtracting a frame tail data value from a K effective data value behind the frame head to obtain the signal intensity of the K LED lamp irradiating the photoelectric detector, and obtaining a signal intensity vector of the position of the photoelectric detector; otherwise, the effective data is lost, the data processing is abandoned, and the visible light receiving module is used for receiving the signal again and processing the signal again.
Specifically, the visible light signal intensity can be obtained while receiving the visible light signal, in this embodiment, except for the end of the pillow frame, the signal transmission is performed in a manner that only one LED lamp is turned on at a time, other LED lamps are turned off completely, and each lamp has a number, so that the signal intensity of each LED lamp can be sequentially obtained in one frame of data, and thus the visible light signal intensity vector can be extracted. The specific method comprises the following steps: finding out the maximum value of signal intensity in the sampling signal as a frame head and the minimum value as a frame tail, and judging whether n effective data exist between the frame head and the frame tail; if the number of the effective data is n, subtracting the frame tail data value from the k (k is 1,2,3, … …, n) th effective data value behind the frame header to obtain the signal intensity of the k-th LED lamp irradiating the photoelectric detector
Obtaining a vector of received signal strength at a location (X, Y) of the photodetector
The invention provides a visible light communication device and a method, which are characterized in that a time division multiplexing-based method is adopted to modulate signals of an LED emission signal, the maximum value and the minimum value of the intensity of a received light signal are used as synchronous information of emission and reception of the visible light signal, the problem of high-precision clock synchronization of LED emission and a photoelectric detector is effectively solved, each frame of data is rapidly identified, and the efficiency of visible light communication is improved.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and units may refer to corresponding processes in the method embodiments, and are not described herein again. In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (4)
1. A visible light communication device, characterized in that the device comprises at least three LED emitting modules and a visible light receiving module, wherein the LED emitting modules are connected with the visible light receiving module in visible light communication; the LED transmitting module comprises an LED lamp and a constant current source driving circuit, and the visible light receiving module comprises an optical filter, a photoelectric detector, an amplifier, an analog-to-digital converter and a microprocessor;
the LED transmitting module is used for loading periodic signals of different time slots in the constant current source driving circuit to modulate transmitted signals, n LED reference points are selected and numbered in the transmitted signal modulation process, 1 frame of signals are averagely divided into n +2 time slots, n LED lamps are fully turned on to serve as frame headers, and n LED lamps are fully turned off to serve as frame tails;
the visible light receiving module is used for receiving an LED light signal through a photoelectric detector, completing photoelectric conversion, inputting the LED light signal to an analog-to-digital converter through an amplifier, and finally transmitting a sampled signal to the microprocessor;
the microprocessor is used for acquiring the maximum value of the signal intensity in the sampling signal as a frame header to represent the start of effective data, and acquiring the minimum value of the signal intensity as a frame tail to represent the end of the effective data to obtain different data frames;
in the LED transmitting module, data k indicates that only the LED lamp with the number k is turned on, other LED lamps are turned off, k is 1,2, …, n, and the modulated visible light signal rate meets the flicker invisible to human eyes;
the microprocessor also extracts a signal intensity vector, judges whether n effective data exist between the frame head and the frame tail, and if the effective data are n, the signal intensity of the photoelectric detector irradiated by the Kth LED lamp is obtained by subtracting a frame tail data value from the Kth effective data value behind the frame head; otherwise, the effective data is lost, the data processing is abandoned, the visible light receiving module is used again to receive the signal, and the signal intensity vector is extracted again.
2. The visible light communication device according to claim 1, wherein the visible light receiving module further comprises a timer, the timer controls a signal acquisition interval of the analog-to-digital converter, and a time of the timer is a time slot length of the LED transmission signal.
3. A visible light communication method is characterized in that a visible light communication device is built, the device comprises at least three LED emission modules and one visible light receiving module, and the method comprises the following steps:
selecting n LED reference points and numbering, loading periodic signals of different time slots in a driving circuit of the LED emission module to modulate emission signals, averagely dividing 1 frame of signals into n +2 time slots, taking n LED lamps as frame headers when the LED lamps are all on, and taking n LED lamps as frame tails when the LED lamps are all off;
a photoelectric detector with an optical filter in the visible light receiving module is used for receiving an LED optical signal and completing photoelectric conversion, and a sampling signal is obtained through an amplifier and an analog-to-digital converter and is input to a microprocessor;
acquiring the maximum value of the signal intensity in the sampling signal as a frame header to represent the start of effective data, and acquiring the minimum value of the signal intensity as a frame tail to represent the end of the effective data, so as to obtain different data frames;
the modulating the transmission signal further comprises:
data k indicates that only the LED with number k is turned on and the other LEDs are turned off, where k is 1,2,3, …, n, and the modulated visible light signal rate satisfies the flicker invisible to human eyes;
the method for acquiring the signal intensity minimum value as the frame end to represent the effective data further comprises the following steps: extracting a received signal strength vector; the specific way of extracting the received signal strength vector is as follows:
judging whether n effective data exist between the frame head and the frame tail, if the effective data are n, subtracting a frame tail data value from a K effective data value behind the frame head to obtain the signal intensity of the K LED lamp irradiating the photoelectric detector, and obtaining a signal intensity vector of the position of the photoelectric detector; otherwise, the effective data is lost, the data processing is abandoned, and the visible light receiving module is used for receiving the signal again and processing the signal again.
4. The visible light communication method according to claim 3, wherein in the analog-to-digital converter, the analog-to-digital acquisition interval is controlled by a timer, and the time of the timer is a time slot length of the LED emission signal.
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| CN103475618A (en) * | 2013-09-21 | 2013-12-25 | 复旦大学 | Method for synchronizing visible light communication system frames based on OFDM |
| CN104243032A (en) * | 2014-08-26 | 2014-12-24 | 南京邮电大学 | Multi-input multi-output visible light communication system synchronization method |
| CN205179051U (en) * | 2015-12-02 | 2016-04-20 | 贵州省计量测试院 | Visible light communication's fast signal restore circuit |
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| US9461752B2 (en) * | 2012-06-30 | 2016-10-04 | Intel Corporation | Methods and arrangements for generating a waveform for frequency shift keying communications |
| US9264138B2 (en) * | 2013-05-16 | 2016-02-16 | Disney Enterprises, Inc. | Reliable visibile light communication with dark light synchronization |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103475618A (en) * | 2013-09-21 | 2013-12-25 | 复旦大学 | Method for synchronizing visible light communication system frames based on OFDM |
| CN104243032A (en) * | 2014-08-26 | 2014-12-24 | 南京邮电大学 | Multi-input multi-output visible light communication system synchronization method |
| CN205179051U (en) * | 2015-12-02 | 2016-04-20 | 贵州省计量测试院 | Visible light communication's fast signal restore circuit |
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