CN107342825A - Wireless light communication Larger Dynamic scope adaptive threshold judgment device and method - Google Patents
Wireless light communication Larger Dynamic scope adaptive threshold judgment device and method Download PDFInfo
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- CN107342825A CN107342825A CN201710748333.6A CN201710748333A CN107342825A CN 107342825 A CN107342825 A CN 107342825A CN 201710748333 A CN201710748333 A CN 201710748333A CN 107342825 A CN107342825 A CN 107342825A
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- 230000006854 communication Effects 0.000 title claims abstract description 54
- 238000004891 communication Methods 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 29
- 230000003044 adaptive effect Effects 0.000 title claims abstract description 18
- 238000000605 extraction Methods 0.000 claims abstract description 31
- 230000003287 optical effect Effects 0.000 claims abstract description 30
- 238000006243 chemical reaction Methods 0.000 claims abstract description 4
- 230000008859 change Effects 0.000 claims description 8
- 238000005070 sampling Methods 0.000 claims description 4
- 230000005622 photoelectricity Effects 0.000 claims 2
- 238000007476 Maximum Likelihood Methods 0.000 abstract description 5
- 238000001514 detection method Methods 0.000 abstract description 4
- 230000005693 optoelectronics Effects 0.000 abstract 1
- 239000000284 extract Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 1
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Classifications
-
- 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
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
- H04B10/695—Arrangements for optimizing the decision element in the receiver, e.g. by using automatic threshold control
-
- 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
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/67—Optical arrangements in the receiver
-
- 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
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
- H04B10/691—Arrangements for optimizing the photodetector in the receiver
Abstract
Wireless light communication Larger Dynamic scope adaptive threshold judgment device and method belong to wireless light communication technical field.Prior art detection dynamic range is small.Receiving optics of the present invention coordinates with PIN photodiode or avalanche photodide, realizes the opto-electronic conversion of optical signal, and the low pass filter of feeding all the way, DSP, FPGA or ASIC of electric signal carry out threshold value extraction, and another way is sent into voltage comparator；Signal intensity relief feature voltage signal either is calculated according to Maximum Likelihood Estimation Method or least square method by one of DSP, FPGA, ASIC as signal intensity relief feature voltage signal in the average voltage for extracting the electric signal by low pass filter；After the signal intensity relief feature voltage signal is admitted to voltage comparator, voltage comparator exports using the signal intensity relief feature voltage signal as decision threshold to being sent to before this after voltage comparator this electric signal all the way makes decisions.Realize the Larger Dynamic scope self-adaptive decision of wireless light communication threshold value.
Description
Technical field
The present invention relates to a kind of wireless light communication Larger Dynamic scope adaptive threshold judgment device and method, belong to wireless optical
Communication technical field.
Background technology
Wireless light communication is the carrier using light as signal, and voice, image and other data messages are realized in free space
Wireless transmission method.With traffic rate is high, message capacity is big, strong antijamming capability, anti-intercepting and capturing ability are strong, small volume, weight
Gently, the advantages of low in energy consumption, it is a kind of very promising wireless communication technology.But, different from fiber optic communication, wireless optical is led to
Believe that its atmospheric channel is sufficiently complex, the unfavorable factor that many influence optical signal transmissions be present, wherein especially using atmospheric turbulance as very.Greatly
Gas turbulent flow can cause optical signal power to be decayed, and the frequency is very high, cause the light signal strength for reaching radio optical communication system receiving terminal
Frequently rise and fall.For the radio optical communication system for taking intensity modulated/direct detection mode, such as on-off keying OOK, by
In its receiving terminal using detection of the threshold value decision method realization to communication data, light signal strength, which rises and falls, can have a strong impact on receiving terminal
Judgement to signal, optimum decision threshold value is caused to change therewith, and actual decision threshold deviation optimum decision threshold value is bigger,
The bit error rate is higher, causes the performance of radio optical communication system to reduce, or even can not realize normal wireless optic communication.
To break away from the influence of the unfavorable factor in atmospheric channel, notification number is that a CN103036616B Chinese invention is special
Profit proposes an entitled " atmospheric radio wave laser communication adaptive threshold judgement side based on pulse spectrum amplitude coding/decoding
The scheme of method ", the program mainly suppress unfavorable factor based on atmospheric turbulance to Scheme for Atmospheric Optical Wireless Communications system in terms of two
Influence：
1st, in advance measurement under conditions of signal is sent photodetection signal corresponding with each optical frequency chip, and with wherein
On the basis of optical frequency chip corresponding to most weak photodetection signal, controlled and other optical frequency chips pair by coding and drive module
The pixel for the linear array LCD space light modulator answered, to reduce the brightness of these pixels, and then make corresponding to each optical frequency chip
Photo detector signal it is strong and weak equal, photodetector adopted here is linear array CCD camera；
2nd, optimum decision threshold value is calculated by likelihood ratio equation, using optimum decision threshold value as threshold value, to line array CCD phase
The signal that machine receives makes decisions, so as to reduce the bit error rate of Scheme for Atmospheric Optical Wireless Communications system.
But there is following technical problem in the prior art：
Because the detection dynamic range of linear array CCD camera is extremely limited, the amplitude of variation of measured amount is not appropriate for very
Big situation, and the distance of wireless light communication is widely varied often, can so cause being widely varied for incident intensity,
The dynamic range that can be detected far beyond linear array CCD camera；Also, the signal of linear array CCD camera output now is not
The change of light signal strength can be accurately reflected, so, when it uses likelihood ratio equation to calculate gained based on the signal most
Excellent decision threshold is not optimal threshold now, then will can not suppress the change pair of communication distance using the threshold value as decision threshold
The influence of radio optical communication system；Equally, the dynamic range of its linear array LCD space light modulator used light modulation also extremely has
Limit, is only capable of being controlled light intensity in the range of very little, is equally difficult to suppress being widely varied of may occurring of communication distance
Influence to radio optical communication system；Further, the linear array CCD camera, the use of linear array LCD space light modulator so that nothing
The complicated of linear light communication system, cost are high, power consumption is high, volume is big.
The content of the invention
In order to which the use eliminated because of linear array CCD camera, linear array LCD space light modulator is brought to wireless light communication comprehensively
Negative effect, we have invented a kind of wireless light communication Larger Dynamic scope adaptive threshold judgment device and method, the present invention
Still it can be normally carried out wireless light communication when communication distance is widely varied, meanwhile, the device of the present invention
Structure, cost, power consumption, volume also improved.
The wireless light communication Larger Dynamic scope adaptive threshold judgment device of the present invention is characterized in that, as shown in figure 1, connect
The image space focal plane for receiving optical system 1 falls on the photosurface of photodetector 2, output end and the power splitter 3 of photodetector 2
Input is connected, and the input of two output ends of power splitter 3 respectively with threshold value extraction module 4, voltage comparator 5 is connected, threshold
The output end of value extraction module 4 is connected to another input of voltage comparator 5；Or as shown in Fig. 2 receiving optics
For 1 emergent light after the light splitting of Amici prism 6, two image space focal planes respectively fall in threshold value photodetector 7, communication photodetector
On 8 photosurface, threshold value photodetector 7, communicate photodetector 8 output end respectively with threshold value extraction module 4, voltage ratio
Input compared with device 5 connects, and the output end of threshold value extraction module 4 is connected to another input of voltage comparator 5；The light
Electric explorer 2, threshold value photodetector 7 and communication photodetector 8 are by PIN photodiode or avalanche photodide
Take on, the threshold value extraction module 4 is taken on by low pass filter, DSP, FPGA or ASIC.
The wireless light communication Larger Dynamic scope adaptive threshold decision method of the present invention is characterized in that, institute as shown in Figure 1, Figure 2
Show, incident optical signal is divided into two-way in a certain ratio, then threshold value extraction module 4, voltage ratio are respectively fed in a manner of electric signal
Compared with device 5, conversion of the incident optical signal to electric signal is completed from PIN photodiode or avalanche photodide；By threshold
Value extraction module 4 extracts the signal intensity relief feature voltage signal caused by the change of communication distance point and atmospheric turbulance, when
When threshold value extraction module 4 is taken on by low pass filter, the average voltage of the electric signal is extracted as signal by low pass filter
Intensity fluctuation character voltage signal, when threshold value extraction module 4 is taken on by DSP, FPGA or ASIC, by DSP, FPGA or
Signal intensity relief feature voltage signal is calculated according to Maximum Likelihood Estimation Method or least square method in ASIC；The signal is strong
After degree relief feature voltage signal is admitted to voltage comparator 5, voltage comparator 5 is with the signal intensity relief feature voltage signal
Exported for decision threshold to being sent to before this after voltage comparator 5 this electric signal all the way makes decisions.
The wireless light communication Larger Dynamic scope adaptive threshold judgment device and method of the present invention its have technical effect that, by
To be far longer than line as electrooptical device, its dynamic range in using PIN photodiode or avalanche photodide
Array CCD camera, in the present invention, also and linear array LCD space light modulator is not used, therefore, the detectable light intensity model of the present invention
Enclose very big.Under the premise of this, optimal threshold is obtained by threshold value extraction module 4, then made decisions by voltage comparator 5, no matter
The optical flare as caused by atmospheric turbulance, or by communication distance change caused by signal intensity fluctuating, especially communicate away from
Significantly risen and fallen from the signal intensity caused by change, the present invention also can effectively eliminate its shadow to wireless light communication process
Ring.
Also it is due to that existing skill is replaced as electrooptical device using PIN photodiode or avalanche photodide
Linear CCD line-scan digital camera used by art, not using linear array LCD space light modulator so that the apparatus structure of the present invention becomes
Simply, cost reductions, lower power consumption, volume reduction.
Because the method for the present invention extracts the average voltage of the electric signal as signal intensity fluctuating by low pass filter
Character voltage signal, signal either is calculated according to Maximum Likelihood Estimation Method or least square method by DSP, FPGA or ASIC
Intensity fluctuation character voltage signal, because required amount of calculation is relatively small compared with the conventional method, computation rate is higher than existing skill
Art, can in real time, quickly provide optimal threshold, this causes the method for the present invention to be fully able to be suitable for suppress because atmospheric turbulance draws
The high frequency time optical flare risen causes influence of the signal intensity high frequency secondary fluctuation to wireless light communication process.
Brief description of the drawings
Fig. 1 be the present invention by power splitter by the wireless light communication Larger Dynamic scope adaptive threshold of incident optical signal branch
Judgment device and method schematic diagram, the figure are used as Figure of abstract simultaneously.
Fig. 2 be the present invention by Amici prism by the wireless light communication Larger Dynamic scope adaptive thresholding of incident optical signal branch
It is worth judgment device and method schematic diagram.
Embodiment
The wireless light communication Larger Dynamic scope adaptive threshold judgment device of the present invention is as shown in figure 1, receiving optics 1
Image space focal plane fall on the photosurface of photodetector 2, the output end of photodetector 2 is connected with the input of power splitter 3,
Power splitter 3 uses one-to-two power splitter, two output ends of power splitter 3 respectively with threshold value extraction module 4, voltage comparator 5
Input connects, and the output end of threshold value extraction module 4 is connected to another input of voltage comparator 5；Or such as Fig. 2 institutes
Show, for the emergent light of receiving optics 1 after the light splitting of Amici prism 6, two image space focal planes respectively fall in threshold value photodetector
7th, communicate photodetector 8 photosurface on, threshold value photodetector 7, communicate photodetector 8 output end respectively with threshold value
The input connection of extraction module 4, voltage comparator 5, the output end of threshold value extraction module 4 are connected to the another of voltage comparator 5
One input；The photodetector 2, threshold value photodetector 7 and communication photodetector 8 are by PIN photodiode
Or avalanche photodide is taken on, the threshold value extraction module 4 is taken on by low pass filter, DSP, FPGA or ASIC.
The wireless light communication Larger Dynamic scope adaptive threshold decision method of the present invention as shown in Figure 1 and Figure 2, believe by incident light
Number it is divided into two-way in a certain ratio, such as 3:7 energy proportions, that is, three points of energy extract for threshold value, and seven points of energy are used to lead to
Letter, provisioning request is power according to incident optical signal to the energy proportion really, premised on optic communication is normally carried out；By work(point
Device 3 or Amici prism 6 complete the branch of incident optical signal.
Threshold value extraction module 4, voltage comparator 5 are respectively fed in a manner of electric signal again afterwards, by PIN photodiode
Or avalanche photodide completes conversion of the incident optical signal to electric signal.Extracted by threshold value extraction module 4 because of communication
Range points change and the signal intensity relief feature voltage signal caused by atmospheric turbulance.When threshold value extraction module 4 is by low pass filtered
When ripple device is taken on, the average voltage of the electric signal is extracted as signal intensity relief feature voltage signal by low pass filter,
Namely the voltage signal of high frequency secondary fluctuation is filtered out by low pass filter, extracts the voltage signal of low frequency secondary fluctuation, equivalent to
Extract the average voltage of the input electrical signal.When threshold value extraction module 4 is taken on by DSP, FPGA or ASIC, by DSP,
Either signal intensity relief feature voltage signal is calculated according to Maximum Likelihood Estimation Method or least square method in ASIC to FPGA.Example
Such as, threshold value extraction module 4 is taken on by ASIC, and ASIC is the integrated circuit specifically for maximum likelihood computing design, and ASIC is from defeated
Threshold value t likelihood function L (x are obtained in the electric signal entered1,x2,…,xn；T), local derviation is asked to L functions, lnL functions with regard to t respectively,
T value is to be sent into the signal intensity relief feature voltage signal of voltage comparator 5 when local derviation is 0, and n is calculating threshold value t in formula
When sampling instant number, x1,x2,…,xnFor the voltage of each sampling instant.
After the signal intensity relief feature voltage signal is admitted to voltage comparator 5, voltage comparator 5 is strong with the signal
Degree relief feature voltage signal be decision threshold to be sent to before this voltage comparator 5 this electric signal all the way make decisions it is rear defeated
Go out.
Claims (5)
1. a kind of wireless light communication Larger Dynamic scope adaptive threshold judgment device, it is characterised in that receiving optics (1)
Image space focal plane falls on the photosurface of photodetector (2), the output end of photodetector (2) and the input of power splitter (3)
Connection, the input of two output ends of power splitter (3) respectively with threshold value extraction module (4), voltage comparator (5) are connected, threshold
The output end of value extraction module (4) is connected to another input of voltage comparator (5)；Or receiving optics (1)
For emergent light after Amici prism (6) light splitting, two image space focal planes respectively fall in threshold value photodetector (7), communication photodetection
On the photosurface of device (8), threshold value photodetector (7), communication photodetector (8) output end respectively with threshold value extraction module
(4), the input connection of voltage comparator (5), the output end of threshold value extraction module (4) are connected to the another of voltage comparator (5)
One input；The photodetector (2), threshold value photodetector (7) and communication photodetector (8) are by PIN photoelectricity
Diode or avalanche photodide are taken on, and the threshold value extraction module (4) is by low pass filter, DSP, FPGA or ASIC
Take on.
2. a kind of wireless light communication Larger Dynamic scope adaptive threshold decision method, it is characterised in that incident optical signal is by a certain
Ratio is divided into two-way, then threshold value extraction module (4), voltage comparator (5) are respectively fed in a manner of electric signal, by PIN photoelectricity
Diode or avalanche photodide complete conversion of the incident optical signal to electric signal；Carried by threshold value extraction module (4)
The signal intensity relief feature voltage signal caused by the change of communication distance point and atmospheric turbulance is taken, when threshold value extraction module
(4) when being taken on by low pass filter, volt extracting the average voltage of the electric signal as signal intensity by low pass filter
Voltage signal is levied, when threshold value extraction module (4) is taken on by DSP, FPGA or ASIC, by DSP, FPGA or ASIC according to very big
Signal intensity relief feature voltage signal is calculated in possibility predication method or least square method；The signal intensity relief feature
After voltage signal is admitted to voltage comparator (5), voltage comparator (5) is using the signal intensity relief feature voltage signal as judgement
Threshold value exports to being sent to before this after voltage comparator (5) this electric signal all the way makes decisions.
3. wireless light communication Larger Dynamic scope adaptive threshold decision method according to claim 2, it is characterised in that institute
It is energy proportion to state ratio, and provisioning request is power according to incident optical signal to the energy proportion really, is normally entered with optic communication
Behavior premise.
4. wireless light communication Larger Dynamic scope adaptive threshold decision method according to claim 2, it is characterised in that by
Power splitter (3) or Amici prism (6) complete the branch of incident optical signal.
5. wireless light communication Larger Dynamic scope adaptive threshold decision method according to claim 2, it is characterised in that when
When threshold value extraction module (4) is taken on by ASIC, ASIC obtains threshold value t likelihood function L (x from the electric signal of input1,x2,…,
xn；T), local derviation is asked L functions, lnL functions with regard to t respectively, t value is to be sent into the signal of voltage comparator (5) when local derviation is 0
Intensity fluctuation character voltage signal, n is the number of sampling instant when calculating threshold value t in formula, x1,x2,…,xnFor each sampling when
The voltage at quarter.
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2017
- 2017-08-28 CN CN201710748333.6A patent/CN107342825A/en active Pending
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| US20070206964A1 (en) * | 2005-08-19 | 2007-09-06 | Korea Advanced Institute Of Science And Technology | Receiver having an apparatus for varying decision threshold level and an optical transmission system having the same |
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| CN106130660A (en) * | 2016-06-30 | 2016-11-16 | 北京大学 | A kind of method of wireless light communication blind Detecting receiver |
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