CN204633777U - The pretreated visible light communication system of a kind of 2ASK - Google Patents
The pretreated visible light communication system of a kind of 2ASK Download PDFInfo
- Publication number
- CN204633777U CN204633777U CN201520352934.1U CN201520352934U CN204633777U CN 204633777 U CN204633777 U CN 204633777U CN 201520352934 U CN201520352934 U CN 201520352934U CN 204633777 U CN204633777 U CN 204633777U
- Authority
- CN
- China
- Prior art keywords
- 2ask
- signal
- communication system
- visible light
- light communication
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Optical Communication System (AREA)
Abstract
The pretreated visible light communication system of the 2ASK that the utility model provides, comprise transmitter module for launching visible ray and for receiving visible ray and visible ray being converted to the receiver module of the signal of telecommunication, wherein, described transmitter module comprises LED drive module and for carrying out pretreated 2ASK pretreatment module to the initial electrical signal entering LED drive module.This visible light communication system, by first carrying out the preliminary treatment of 2ASK to signal, can make the signal be modulated on LED can not produce obvious distortion, and can improve LED drive circuit on this basis, increases degree of light modulation, makes transmission range farther.
Description
Technical field
The utility model relates to visible light communication field, in particular to the pretreated visible light communication system of 2ASK.
Background technology
Visible light communication (VLC) is a kind of novel wireless light communication technology based on white light emitting diode (LED), and illumination and communication two large functions can unite two into one by it.At present, the comparatively simple modulation system of visible light communication system has OOK and PPM two kinds, they all belong to digital baseband modulation, directly remove modulating light pulse, transmitted signal is represented respectively with the position of the presence or absence of light pulse and light pulse, and the research emphasis of correlation technique is placed in transmission rate mostly, seldom to improve transmission range as further impr-vement.
For the modulation of conventional digital baseband, being mounted in essence, LED light source is a digital signal, can obtain higher harmonic components by Fourier transform analysis.Consider that the various electronic components (triode etc. as in drive circuit) in transmitting terminal circuit have certain gain bandwidth product, and because white light LEDs is by the impact of self phosphorus fluorescent material, its effective three dB bandwidth is only about 1MHz, the digital signal be modulated on LED has certain distortion, the waveform that influential system transmits.On the other hand, in actual applications user in larger scope, is necessary to make the transmission range of communication system to become farther, so that can receive signal.
Utility model content
For above problem, the utility model provides the pretreated visible light communication system of a kind of 2ASK, binary system amplitude-shift keying (2ASK) pretreated modulation drive circuit is carried out to light source, the signal be modulated on LED can be made like this can not to produce obvious distortion, and can LED drive circuit be improved on this basis, increase degree of light modulation, make transmission range farther.
The pretreated visible light communication system of a kind of 2ASK, comprise transmitter module for launching visible ray and for receiving visible ray and visible ray being converted to the receiver module of the signal of telecommunication, wherein, described transmitter module comprises LED drive module and for carrying out pretreated 2ASK pretreatment module to the initial electrical signal entering LED drive module.
Further, described 2ASK pretreatment module comprises for generation of the active crystal oscillator of carrier signal, for carrying out the frequency selection circuit of frequency-selecting and the analog switch for the carrier signal after frequency-selecting to be carried out signal switching output according to input signal to carrier signal.
Further, the described LED drive module signal of telecommunication comprised for being modulated by 2ASK pretreatment module carries out the common collector amplifying circuit of magnitude of current amplification.
Further, described LED drive module is provided with direct current biasing.
Further, described receiver module comprises the photoelectric tube for LED lamplight being converted to photoelectric current, for transferring photoelectric current to voltage and having the preamplifier of amplification performance, and for unnecessary low frequency signal being carried out the high-pass filtering circuit of filtering.
Further, described photoelectric tube adopts photovoltaic mode to carry out work.
Further, described high-pass filtering circuit adopts voltage controlled voltage source second order high-pass filtering circuit.
Further, described transmitter module comprises the main amplifier for carrying out amplifying through the signal of enlarge leadingly and filtering further, and for the signal through main amplifier process being carried out modulate and the demodulation of shaping and shaping circuit
Further, described demodulation and shaping circuit adopt Schottky diode halfwave rectifier, are carried out the demodulation of envelope detection method by RC circuit low-pass filtering.
Further, described demodulation and shaping circuit adopt the shaping circuit be made up of zero-crossing comparator.
The pretreated visible light communication system of 2ASK of the present utility model, before modulation LED light source, add binary system amplitude-shift keying (2ASK) modulation circuit to initial electrical signal, the more modulated signal of telecommunication is input to LED drive circuit, analog intensity modulation is carried out to light source.This is different from digital baseband modulation in the past, and what adopt due to 2ASK modulation is the sine wave of fixed frequency, when being modulated to light source, and can not because of the situation producing distortion containing high order harmonic component.
Accompanying drawing explanation
Fig. 1 is the structure chart of the pretreated visible light communication of 2ASK of the present utility model;
The embodiment that Fig. 2 is the 2ASK pretreatment module shown in Fig. 1;
The embodiment that Fig. 3 is the LED drive module shown in Fig. 1;
The embodiment that Fig. 4 is the pre-amplification circuit shown in Fig. 1;
The embodiment that Fig. 5 is the circuit of high pass filter shown in Fig. 1;
The embodiment that Fig. 6 is the main amplifying circuit shown in Fig. 1;
The embodiment that Fig. 7 is the demodulation shown in Fig. 1 and shaping circuit.
Embodiment
Also by reference to the accompanying drawings the utility model is described in further detail below by concrete execution mode.
As shown in Figure 1, the pretreated visible light communication system of 2ASK comprises the transmitter module of launching visible ray and for receiving visible ray and visible ray being converted to the receiver module of the signal of telecommunication.Transmitter module comprises LED drive module and for carrying out pretreated 2ASK pretreatment module to the initial electrical signal entering LED drive module.Receiver module comprises the photoelectric tube for LED lamplight being converted to photoelectric current, for transferring photoelectric current to voltage and there is the preamplifier of amplification performance, for unnecessary low frequency signal being carried out the high-pass filtering circuit of filtering, for the main amplifier amplified enlarge leadingly and filtered signal, and for the signal through main amplifier process being carried out demodulation and the shaping circuit of separating mediation shaping.
About transmitter module:
Signal source input initial electrical signal is passed to LED drive module after the process of 2ASK pretreatment module, and LED drive module connects several high-powered LED lamp.
The modulation system of 2ASK pretreatment module converts high level to the carrier wave of fixed frequency, overcome the problem of transmitting terminal distorted signals on the one hand, and make that receiving terminal is more convenient carries out filtering, on the other hand, in order to make modulated signal more stable, accurate, use active crystal oscillator to produce the sinusoidal carrier signal of a 1MHz, and add the frequency selection circuit of crystal oscillator and analog switch (4066BD) forms modulation circuit, as shown in Figure 2.
Among the present embodiment, in circuit, select high-frequency triode 2SC1815, made the peak value of carrier wave enough large; Frequency selection circuit is tuned near 1MHz, guarantees that sinusoidal carrier does not have unwanted noise.Modulation signal inputs from the S1 mouth of 4066BD, and modulated signal outputs to LED drive module from D1 mouth.In theory, if the total bandwidth of transmitter module can reach more than 1MHz, the modulation signal measured at LED place just can not distortion.
From P-I curve, direct current biasing line should be positioned at the midpoint of linear segment as far as possible, under distortionless prerequisite, modulation signal is trended towards maximum, and degree of light modulation namely can be made maximum.Object is the change allowing receiving terminal more easily detect light signal, the total optical power size needed for reduction.
As shown in Figure 3, in order to drive high-powered LED lamp, drive circuit adopts common collector type amplifying circuit, the magnitude of current of modulated signal fully can be amplified like this, gives LED direct current biasing again simultaneously, makes it the linear segment midpoint being operated in P-I curve.
Should be understood that, each LED lamp bead should add aluminium base base respectively, to make it to reach radiating effect.
About receiver module:
Photoelectric tube (adopting PIN photodiode among the present embodiment) connects preamplifier, preamplifier connects high-pass filtering circuit, high-pass filtering circuit connects main amplifying circuit, and main amplifying circuit connects envelope detection circuit, and envelope detection circuit connects shaping circuit.
PIN photodiode selects model to be BPW34, and photosurface is square, has the advantages that dark current is little, highly sensitive, is suitable in visible light communication system.In order to avoid the interference of noise on circuit, and consider PIN photodiode more accurately linear work, this circuit adopts photovoltaic mode (Zero-bias working pattern).In Fig. 3, R1 is as current-limiting resistance, and R2, C1 form negative-feedback circuit, amplification input signal, and R3 is as the compensating resistance of operational amplifier positive pole.
Preamplifier in receiver module, concerning particularly important rear class, both played effect photoelectric current being changed into voltage, had had again certain amplification performance.According to multistage effect, preamplifier is as the first order of receiving terminal, the feature that noise is less, bandwidth is larger must be had, this device has selected the LM4562 in ultra-low-distortion, low noise, high conversion rate operational amplifier, its switching rate reaches 20V/ μ s, gain bandwidth product reaches 55MHz, meets the requirement of preamplifier, and the circuit be made up of LM4562 as shown in Figure 4.
Visible light communication system can receive the bias light coming from incandescent lamp, sunlight etc., and they all belong to low frequency signal.The second level of this module adopts voltage controlled voltage source second order high-pass filtering circuit, and all filterings of unnecessary low-frequency component, reduce ideal 2ASK modulation waveform, be conducive to the signal transacting of rear class, circuit as shown in Figure 5.
The cut-off frequency fp of circuit is determined by R, C, and the value of fp should a little less than carrier frequency 1MHz, and Rf and R1 determines multiplication factor, should not amplify too many times herein, because under the prerequisite that gain bandwidth product is certain, gain too conference causes bandwidth to diminish.
Through enlarge leadingly, filtered signal, its amplitude size fails to meet the threshold condition of demodulation far away, so have to pass through further amplification.Because carrier frequency is higher, according to the multistage amplifier circuit of high-frequency triode composition, not only can be cost-saving, gain factor more better than operational amplifier can also be obtained.But when using transistor amplifier, need the problem considering impedance matching carefully at input/output port place, the main amplifier performance that the use in conjunction with voltage follower can allow triode form is better.According to the actual signal magnitude received, adjustable resistance resistance obtains the circuit of different multiplication factor, and roughly circuit as shown in Figure 6.
At receiving terminal, the demodulation method of 2ASK signal has two kinds, i.e. envelope detection method and coherent demodulation method.Can realize because coherent demodulation needs to obtain synchronizing signal more accurately, this device adopts envelope detection method.This method will note two aspects: the relation of input voltage and output voltage; Discharge time when charging interval during diode current flow and cut-off, and inertia distortion and bottom will be avoided to cut distortion.So, the concrete value of R, C must be obtained by analog computation, meet above condition.The value size calculated according to the carrier frequency of this device as shown in Figure 7.
This device, by Schottky diode halfwave rectifier, carrys out demodulation by RC circuit low-pass filtering.Find that the waveform after envelope detection is still undesirable, so add a shaping circuit be made up of zero-crossing comparator at end, thus obtain more good-looking signal waveform.
The transmitter module course of work illustrates:
From transmitting terminal, produce 1MHz by crystal oscillator vibration sinusoidal wave, be input in the frequency-selective network be tuned under same frequency, obtain and do not have noisy 1MHz carrier wave.This road of carrier wave is input in analog switch (4066BD) IN1 pin, and need the signal sent to be input in the S1 pin of analog switch, can obtain a modulated signal at analog switch D1 place, this process is exactly the preliminary treatment to signal.Above-mentioned gained modulated signal is input in LED drive circuit, and drive circuit amplifies modulated signal, after adding again a direct current biasing, signal madulation in the LED lamp bead of several 1W.LED, as the instrument signal of telecommunication being converted to light signal, launches the signal of telecommunication after modulation with the form of visible ray.
The receiver module course of work illustrates:
After optical channel is propagated, useful light signal mixes bias light and enters into receiving terminal together.All light is received by PIN photodiode, PIN photodiode becomes the signal of telecommunication light signal with the formal transformation of photoelectric current and is input in preamplifier, preamplifier becomes photoelectric current into voltage, and amplifies certain multiple, and the electric capacity in its circuit has the effect of denoising.In order to the low-frequency noise further bias light brought is removed, the signal after preamplifier process is input in high-pass filtering circuit, by second-order filter, enough thorough for low frequency signal filtering, obtains the 2ASK modulation signal that waveform is similar to transmitting terminal.
Because up to the present obtained signal amplitude is large not, the condition of demodulation can not be met, need the signal of high pass filter to be input in main amplifier again to amplify.By the triode total radio amplifier in main amplifier, signal can be amplified more than tens to one hundred times, again the signal after amplification is input in envelope detection circuit, after the halfwave rectifier of Schottky diode, restituted signal can be obtained after RC low-pass filtering.Because the quality of restituted signal is desirable not enough, available zero-crossing comparator carries out shaping, is finally reduced into the signal that approach signal source is original sent, and reaches the object of transmission.
Visible light communication system among prior art, cannot solve following problem well: 1, when carrying out digital baseband modulation to light source, the signal be carried on white light LEDs can produce obvious distortion because of finite bandwidth; 2, the luminous power of large power white light LED drive circuit is smaller, is unfavorable for making transmission range farther; 3, due to white light abundance, a large amount of bias lights is had in visible light communication as interference.
The visible light communication system of this specific embodiment is achieved in that first, before modulation LED light source, add binary system amplitude-shift keying (2ASK) modulation circuit to initial electrical signal, the more modulated signal of telecommunication is input to LED drive circuit, analog intensity modulation is carried out to light source.This is different from digital baseband modulation in the past, and what adopt due to 2ASK modulation is the sine wave of fixed frequency, when being modulated to light source, and can not because of the situation producing distortion containing high order harmonic component; The second, improve LED drive circuit, improve the ratio of modulation signal electric current and bias current in circuit, namely according to the P-I curve of LED, thus improve degree of light modulation, can, when illuminance is certain, make transmission range farther like this; 3rd, coordinate the signal after 2ASK modulation, at receiving terminal design enlarge leadingly, high-pass filtering, envelope detection demodulator circuit.Because the sinusoidal carrier frequency of 2ASK employing is much larger than the frequency of bias light, make the filter effect of receiving terminal very good, system is hardly by the interference of ambient light.
According to the visible light communication system that above-mentioned specific embodiment makes, modulation signal is first carried out 2ASK modulation, use the LED of 5 1W to launch, and received by PIN photoelectric diode (BPW34).During test, by the square wave of signal generator as modulation signal, by analog switch and crystal oscillating circuit modulation, can observation signal receives on digital oscilloscope effect after receiving demodulation.The results show, the illuminance that the LED of 5 1W sends is 2290LX, and fixed transmission end is motionless, from apart from mobile reception end its 100cm place, if modulating frequency elects 50kHz as, until the correct square-wave signal of duty ratio all can be recovered at receiving terminal by range transmission end 500cm place.And when transmission range is greater than 503cm, duty ratio starts to change, can not proper communication.Can obtain conclusion is, when modulating frequency is 50kHz, transmission range is maximum reaches 503cm, and the communication system that can be used as the longer distance of low speed uses.
The above embodiment only have expressed several execution mode of the present utility model, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the utility model the scope of the claims.It should be pointed out that for the person of ordinary skill of the art, without departing from the concept of the premise utility, can also make some distortion and improvement, these all belong to protection range of the present utility model.Therefore, the protection range of the utility model patent should be as the criterion with claims.
Claims (10)
1. the pretreated visible light communication system of 2ASK, it is characterized in that, comprise transmitter module for launching visible ray and for receiving visible ray and visible ray being converted to the receiver module of the signal of telecommunication, wherein, described transmitter module comprises LED drive module and for carrying out pretreated 2ASK pretreatment module to the initial electrical signal entering LED drive module.
2. the pretreated visible light communication system of 2ASK according to claim 1, it is characterized in that, described 2ASK pretreatment module comprises for generation of the active crystal oscillator of carrier signal, for carrying out the frequency selection circuit of frequency-selecting and the analog switch for the carrier wave after frequency-selecting to be carried out signal switching output according to input signal to carrier signal.
3. the pretreated visible light communication system of 2ASK according to claim 1, is characterized in that, the described LED drive module signal of telecommunication comprised for being modulated by 2ASK pretreatment module carries out the common collector amplifying circuit of magnitude of current amplification.
4. the pretreated visible light communication system of 2ASK according to claim 1, is characterized in that, described LED drive module is provided with direct current biasing.
5. the pretreated visible light communication system of 2ASK according to claim 1, it is characterized in that, described receiver module comprises the photoelectric tube for LED lamplight being converted to photoelectric current, for transferring photoelectric current to voltage and there is the preamplifier of amplification performance, and for unnecessary low frequency signal being carried out the high-pass filtering circuit of filtering.
6. the pretreated visible light communication system of 2ASK according to claim 5, is characterized in that, described photoelectric tube adopts photovoltaic mode to carry out work.
7. the pretreated visible light communication system of 2ASK according to claim 5, is characterized in that, described high-pass filtering circuit adopts voltage controlled voltage source second order high-pass filtering circuit.
8. the pretreated visible light communication system of 2ASK according to claim 5, it is characterized in that, described transmitter module comprises the main amplifier for carrying out amplifying through the signal of enlarge leadingly and filtering further, and for the signal through main amplifier process being carried out modulate and the demodulation of shaping and shaping circuit.
9. the pretreated visible light communication system of 2ASK according to claim 8, is characterized in that, described demodulation and shaping circuit adopt Schottky diode halfwave rectifier, is carried out the demodulation of envelope detection method by RC circuit low-pass filtering.
10. the pretreated visible light communication system of 2ASK according to claim 8, is characterized in that, described demodulation and shaping circuit adopt the shaping circuit be made up of zero-crossing comparator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520352934.1U CN204633777U (en) | 2015-05-19 | 2015-05-27 | The pretreated visible light communication system of a kind of 2ASK |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520328934 | 2015-05-19 | ||
| CN2015203289348 | 2015-05-19 | ||
| CN201520352934.1U CN204633777U (en) | 2015-05-19 | 2015-05-27 | The pretreated visible light communication system of a kind of 2ASK |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204633777U true CN204633777U (en) | 2015-09-09 |
Family
ID=54052756
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520352934.1U Expired - Fee Related CN204633777U (en) | 2015-05-19 | 2015-05-27 | The pretreated visible light communication system of a kind of 2ASK |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN204633777U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104821851A (en) * | 2015-05-19 | 2015-08-05 | 华南师范大学 | 2ASK preprocessing visible light communication system |
| CN110779187A (en) * | 2019-11-04 | 2020-02-11 | 广东美的暖通设备有限公司 | Signal transmitting device, signal receiving device, communication device and air conditioner |
-
2015
- 2015-05-27 CN CN201520352934.1U patent/CN204633777U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104821851A (en) * | 2015-05-19 | 2015-08-05 | 华南师范大学 | 2ASK preprocessing visible light communication system |
| CN110779187A (en) * | 2019-11-04 | 2020-02-11 | 广东美的暖通设备有限公司 | Signal transmitting device, signal receiving device, communication device and air conditioner |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104821851A (en) | 2ASK preprocessing visible light communication system | |
| CN104485993B (en) | Vehicular visible light wireless digital voice communication system | |
| US10680719B2 (en) | Electronic device associated with a photovoltaic module to optimise the throughput of a bidirectional VLC transmission | |
| CN103117826A (en) | Voice broadcaster implemented by aid of visible light wireless communication | |
| CN103595470B (en) | A kind of low-power-consumption infrared optical communication system | |
| Pradana et al. | VLC physical layer design based on pulse position modulation (PPM) for stable illumination | |
| CN103763031A (en) | Communication terminal and communication system achieving communication through visible light | |
| CN204633777U (en) | The pretreated visible light communication system of a kind of 2ASK | |
| CN104980218A (en) | Optical-filter-free visible light communication system | |
| CN104601234A (en) | High-speed weak signal obtaining circuit | |
| CN105071855B (en) | Visible light communication system and LED are non-linear to its performance impact analysis method | |
| CN205179057U (en) | Receiving arrangement of visible light communication system based on white light LED | |
| CN105471505A (en) | Signal modulation method, signal modulation device, and visible light communication system | |
| CN206389368U (en) | Visible light communication receiving circuit based on high frequency network transformer | |
| Zhu et al. | Visible Light Communication System Based on White LED | |
| Sayco et al. | Design and implementation for a USRP–based visible light communications transceiver | |
| CN211239852U (en) | Ultraviolet light communication receiving device based on frequency shift keying | |
| CN112019273A (en) | Two-way wireless audio transmission system based on white light LED | |
| Li et al. | A 2.2-mW 24-Mb/s CMOS LiFi receiver system-on-a-chip with ambient light rejection and post-equalization | |
| Zaiton et al. | Performance characterization of phase shift keying modulation techniques for indoor visible light communication system | |
| CN203788290U (en) | LED glare flashlight and visible light based portable emergency communication system | |
| Zhang et al. | VLC system implementation with white LEDs | |
| CN112763520B (en) | High-flux visible light image transmission system for root system CT scanning imager | |
| CN215818156U (en) | Indoor visible light audio communication system based on white light LED | |
| Fuada et al. | Automatic Gain Control Circuit for Mobility Visible Light Communication System using LM13700 |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150909 Termination date: 20160527 |