CN110261356A - A kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method - Google Patents
A kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method Download PDFInfo
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
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- G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
- G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
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Abstract
A kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method, including lower computer system and upper computer module, the lower computer system (1000) is with metal shielding (1010), optical-fibre channel (1011), PD dissolved oxygen film (1012) and convex lens (1013) are designed as structure, data acquisition is realized by acquiring transmission module (1003) in slave computer, fft algorithm processing, system control, temperature is read, and data after pretreatment are sent to by upper computer module by serial port module (1002), to facilitate the data transmission and control of computer (1100) and modules；Computer (1100) is handled for further to collected information, finally obtains required content of oxygen dissolved in water and part relevant parameter, and real-time display testing result.Precision of the present invention is high, detection speed is fast, strong real-time.
Description
Technical field
The present invention relates to sensor detecting fields, and in particular to a kind of online oxygen in water measuring system.
Background technique
The content of oxygen in water concentration is an important indicator of evaluating water quality, is one of water quality normal five, by molten
Solution oxygen detection device can be realized the real-time monitoring to oxygen in water, can in conjunction with other monitoring parameters such as pH value, turbidity
Quickly to obtain water quality condition, and then carry out related renovation in time.Moreover, the measurement of dissolved oxygen is in wine-making technology,
Also all tool has important application for paper technology, metallurgical technology and biomedical aspect.
The method that traditional dissolved oxygen sensing technology mainly has titration iodimetric titration and electrochemistry, wherein titration iodimetric titration is one
The typical chemical detection method of kind, it not only needs to consume the sample dissolved oxygen of certain content, and its program is cumbersome, time-consuming
It is long, it is unable to satisfy the requirement of on-line measurement.And it uses sensor made of the method for electrochemistry then to exist and is easy to be contaminated, need
It is often replaced and cleaned, there is the defects of unstable and easy failure.In contrast, Fluorimetric Quenching Method has good photochemistry steady
The advantages that qualitative, reproducibility is non-delay, and precision is high, and the service life is long, and then the dissolved oxygen in water can be detected in real time.
Therefore, water quality detection require promotion so that people to use Fluorimetric Quenching Method carry out dissolved oxygen content detection more favor.
At home, many business research or colleges and universities all carried out certain this aspect theoretical research and experiment survey
Examination, but be capable of the completion research and development of products of system and make high-resolution, quick response commercialization instrument at home also compared with
It is few, Fluorimetric Quenching Method principle is equally used, however final detection accuracy is different, therefore studies using which kind of design and calculate
Method, which completes phase difference measurement, becomes the key component for designing a kind of high-precision dissolved oxygen sensor.
Summary of the invention
In order to solve the problems such as detection dissolved oxygen content precision is low, detection process is cumbersome, detection cycle is long, the present invention is provided
A kind of online high-precision dissolved oxygen detection system, is improved in precision to realize, uses Fluorimetric Quenching Method detection side
Method cooperation FFT phase difference technology is detected, and the generation and acquisition of signal are carried out using 24 high-precision ADs/DA；In order to subtract
Few detection time carries out parallel computation to algorithm using the characteristics of its parallel organization using the FPGA of XILINX company.
The technical solution adopted by the present invention to solve the technical problems is:
A kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method, including lower computer system and upper computer module；
The lower computer system acquires for realizing data, fft algorithm is handled, system controls, temperature is read and will count after pretreatment
According to upper computer module is sent to, to facilitate the data transmission and control of computer (1100) and modules；Computer (1100)
For being handled collected information is further, required content of oxygen dissolved in water and part relevant parameter are finally obtained,
And real-time display testing result.
Further, the lower computer system includes dissolved oxygen acquisition and main control module (1000), Metal shielding shell
(1010), optical-fibre channel (1011), PD high temperature dissolved oxygen film (1012) and convex lens/optical filter (1013), by dissolved oxygen acquisition and
Main control module (1000) launches 650nm reference light (2004) according to certain frequency and 395nm exciting light (2005) passes through optical fiber
Channel (1011), which is got on PD high temperature dissolved oxygen film (1012), occurs fluorescent quenching reaction, the reflection of 650nm reference light (2004)
The fluorescence that light and 395nm exciting light (2005) generate on dissolved oxygen film (1012) by convex lens/optical filter (1013) respectively by
PD Acquisition Circuit (3000) in acquisition and control module (1003) is acquired.
The metal shielding (1010) is for be electromagnetically shielded and provide the waterproof function of system to total system
Can, meet testing requirements in the water of certain depth；
The optical-fibre channel (1011) ensure that 650nm reference light (2004) in acquisition and control module (1003) and
395nm exciting light (2005) can lossless arrival PD high temperature dissolved oxygen film (1012), and by the channel by control section and
High-temperature water (150 degrees Celsius) is isolated, to realize that high-temperature water dissolved oxygen content detects；
The PD dissolved oxygen film (1012) makes dissolved oxygen film PyxisPd, same Ocean by oneself using Qi Pan Science and Technology Ltd.
The comparison of the finished products such as Optics fluorescent film has consistent level of sensitivity and higher temperature-resistance characteristic, is applicable in scene more horn of plenty；
The convex lens and optical filter (1013) are used for 650nm reference light (2004) and 395nm exciting light (2005)
The reflected light and fluorescence of generation are converged and are filtered out heterogeneous light, are guaranteed that the light passed through is the light of single wavelength, are further ensured that
The detection accuracy of system.
The dissolved oxygen acquisition and main control module (1000) include power module (1001), serial port module (1002) and adopt
Collection and control module (1003), the acquisition and control module (1003) are divided into two parts, signal generate first part by
FPGA controller (2000), digital analog converter (2001), voltage/current conversion circuit (2002), selector circuit (2003),
650nm wavelength reference light point light source of single (2004), 395nm wavelength exciting light point light source of single (2005) composition；Signal acquisition part
By PD Acquisition Circuit (3000), current/voltage converter circuit (3001), low-pass filter (3002), in-phase amplifier (3003)
It is formed with analog to digital conversion circuit (3004).
FPGA controller (2000) sends 24 sinusoidal sequences of fixed frequency all the way to 24 digital-to-analogue conversion cores by DDS
The sinusoidal signal of piece (2001), generated fixed frequency is selected by voltage/current conversion circuit (2002) in certain frequency
Reference luminous point light source (2004) and exciting light point light source (2005) are lighted under the gating of device (2003) respectively；
PD sensor (3000) is converted to collected optical signal after electric signal through overcurrent voltage conversion circuit
(3001) sinusoidal signal under fixed frequency is obtained, is filtered by low-pass filter (3002) and amplifier in the same direction (3003)
And signal shaping, it is input to analog-digital converter (3004) and is followed by FPGA controller (2000) completion signal processing；
The power module (1001) is used to be powered dissolved oxygen acquisition and main control module (1000)；
The serial port module (1002) is communicated using RS-485 mode and computer (1100), send in real time and
Receive pretreated dissolved oxygen data；
The FPGA controller (2000) is used to export the sinusoidal signal that 24 sinusoidal sequences generate fixed frequency, and right
Calculated result is sent to calculating by serial port module (1002) after the data progress FFT calculating that analog-digital converter (3004) obtains
Machine (1100)；
The digital analog converter (2001) uses 24 high-precision AD conversion chips, is used for FPGA controller (2000)
24 sinusoidal sequences of output are converted to the sinusoidal waveform of fixed frequency, retransmit to voltage/current conversion circuit (2002)；
The voltage/current conversion circuit (2002) is built by double operational, is controlled by control transfer resistance resistance value
Size of current, when transfer resistance is set as R, input voltage U, output electric current is I=U/R.Output electric current is accessed into selector
Circuit (2003) input pin；
The selector circuit (2003) drives LED point light source for gating, and is controlled by FPGA controller (2000),
650nm wavelength reference light point light source of single (2004) and 395nm wavelength exciting light are respectively driven with certain frequency using input current
Point light source of single (2005)；
The point light source is divided into the reference source (2004) of 650nm and the excitation light source (2005) of 395nm, molten according to PD
The absorption and reflection characteristic to light sources with different wavelengths of oxygen film (1012), reference source (2004) can directly reflect on film, instead
It penetrates light and reaches PD sensor (3000) by optical filter/convex lens (1013).Excitation light source (2005) is by PD dissolved oxygen film (1012)
Fluorescence is issued after absorption reaches PD sensor (3000) by optical filter/convex lens (1013)；
The PD Acquisition Circuit (3000), will for the reference source (2004) and fluorescence of reflection to be acquired and converted
Optical signal is converted to electric signal, and the form of expression is current signal, the signal be input in current/voltage converter circuit (3001) into
Row conversion；
The low-pass filter (3002) and in-phase amplifier (3003) be used for obtained signal be filtered with it is whole
Shape meets analog-digital converter (3004) input requirements；
The analog-digital converter (3004) uses 24 bit resolution high-precision AD conversion chips, for the sampling to signal,
Sample frequency is 48MHz, meets Sampling Theorem greater than signal frequency 2 times or more.
The computer (1100) includes parameter setting unit (1101), data processing unit (1102), data display list
First (1103) and data storage element (1104), parameter designing unit (1101) to the sine wave freuqency of transmission, reference source and
Excitation light source gating control frequency parameter is controlled；Data processing unit (1102) completes the reception to FFT calculated result, and
The phase at two paths of signals setting frequency point is calculated, and then obtains phase difference；Data display unit (1103) is used for data
The phase real-time display of phase difference and each signal；Dissolved oxygen content before the correction that data storage element (1104) will acquire
Dissolved oxygen content value, the phase difference of two paths of signals and the independent phase of each signal are protected in a manner of EXCEL after value, correction
It deposits.
The parameter setting unit (1101) completes to be configured salinity water to be measured, pneumatic parameter, and according to setting
Parameter completes dissolved oxygen content compensation；
The data processing unit (1102) is broadly divided into two parts, and first part is that dissolved oxygen content calculates, and second
Part is that dissolved oxygen content is calibrated, and computer (1100) receives the FFT calculated result of serial port module (1002) transmission, for connecing
The real and imaginary parts data of each frequency point are received, setting sample rate is f, and FFT points are a point, then the frequency point after carrying out FFT
Resolution are as follows:
And carrying out the corresponding frequency of N point after FFT is f1* (N-1) KHz, therefore be f at F frequency1* (F-1) KHz point,
Only need to calculate separately the phase of this point in reference light and fluorescence FFT calculated result, reference can be acquired by subtract each other
Phase difference between light and fluorescence sinusoidal signal；
Dissolved oxygen concentration is not only related with temperature, and related with the content of air pressure, salinity, parameter setting and data school
Positive module mainly completes the setting of measurement parameter and the correction display function of dissolved oxygen concentration；
After the phase difference for obtaining reference light and fluorescence, the concentration of dissolved oxygen is calculated according to saturated dissolved oxygen solution formula
Value, while according to experimental calibration as a result, the calculated result to oxyty carries out salinity compensation；；
p、poRespectively actual measurement and standard atmospheric pressure, unit Kpa；T is the temperature of saturated dissolved oxygen water body, and unit is
℃；
The data display unit (1103) is divided into two parts, and first part is phase difference display figure, and second part is
Dissolved oxygen figure shows that wherein the currently practical phase difference variation of phase difference display portion real-time display, dissolved oxygen display portion are real-time
Show the dissolved oxygen content of current detection water quality.
The online dissolved oxygen sensing instrument is directly anchored to certain depth in actual measurement content of oxygen dissolved in water
In water, the data that lower computer system collects are transmitted in upper computer module by RS-485 bus mode completes real time data
Processing and display, upper and lower computer are attached by shielded cable.
The present invention designs a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method, passes through FPGA combination FFT method
The phase difference of reference light and exciting light is detected, measures the variation of fluorescence lifetime indirectly.And it is completed by sensor to water
Middle temperature and the acquisition of Simultaneous Pressure data.The advantages of making full use of hardware design is protected using the design method of single channel circuit
It is consistent to demonstrate,prove external disturbance suffered by circuit of light sources, promotes detection accuracy.FPGA can be faster complete using parallel computation in the design
The processing of paired data further increases detection speed.Final dissolved oxygen content is carried out using temperature and pressure testing result
Calibration, obtains more accurate dissolved oxygen value.
Beneficial effect of the present invention is mainly manifested in: precision is high, detection speed is fast, strong real-time.
Detailed description of the invention
Fig. 1 is the online dissolved oxygen sensing system structure schematic block diagram of Fluorimetric Quenching Method.
Fig. 2 is sine wave signal generation system structural schematic block diagram.
Fig. 3 is PD acquisition system structural schematic block diagram.
Fig. 4 is the online dissolved oxygen sensing system flow chart of Fluorimetric Quenching Method.
Specific embodiment
More detailed description is carried out with reference to the accompanying drawing:
Referring to Fig.1~Fig. 4, a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method, including lower computer system
And upper computer module；The lower microsystem for realizing data acquire, fft algorithm processing, system control, temperature read and
Data after pretreatment are sent to upper computer module, to facilitate the data transmission and control of computer (1100) and modules；
Computer (1100) is handled for further to collected information, finally obtains required content of oxygen dissolved in water and portion
Divide relevant parameter, and real-time display testing result.
Further, the master system includes dissolved oxygen acquisition and main control module (1000), Metal shielding shell
(1010), optical-fibre channel (1011), PD high temperature dissolved oxygen film (1012) and convex lens/optical filter (1013), by dissolved oxygen acquisition and
Main control module (1000) launches 650nm reference light (2004) according to certain frequency and 395nm exciting light (2005) passes through optical fiber
Channel (1011), which is got on PD high temperature dissolved oxygen film (1012), occurs fluorescent quenching reaction, the reflection of 650nm reference light (2004)
The fluorescence that light and 395nm exciting light (2005) generate on dissolved oxygen film (1012) by convex lens/optical filter (1013) respectively by
PD Acquisition Circuit (3000) in acquisition and control module (1003) is acquired.
The metal shielding (1010) is for be electromagnetically shielded and provide the waterproof function of system to total system
Can, meet testing requirements in the water of certain depth.
The optical-fibre channel (1011) ensure that 650nm reference light (2004) in acquisition and control module (1003) and
395nm exciting light (2005) can lossless arrival PD high temperature dissolved oxygen film (1012), and by the channel by control section and
High-temperature water (150 degrees Celsius) is isolated, to realize that high-temperature water dissolved oxygen content detects.
The PD dissolved oxygen film (1012) makes dissolved oxygen film PyxisPd, same Ocean by oneself using Qi Pan Science and Technology Ltd.
The comparison of the finished products such as Optics fluorescent film has consistent level of sensitivity and higher temperature-resistance characteristic, is applicable in scene more horn of plenty.
The convex lens and optical filter (1013) are used for 650nm reference light (2004) and 395nm exciting light (2005)
The reflected light and fluorescence of generation are converged and are filtered out heterogeneous light, are guaranteed that the light passed through is the light of single wavelength, are further ensured that
The detection accuracy of system.
Dissolved oxygen acquisition and main control module (1000) further by power module (1001), serial port module (1002) with
And acquisition and control module (1003) are formed.Further, the acquisition and control module (1003) are divided into two parts, signal
First part is generated by FPGA controller (2000), digital analog converter (2001), voltage/current conversion circuit (2002), selection
Device circuit (2003), 650nm wavelength reference light point light source of single (2004), 395nm wavelength exciting light point light source of single (2005) composition；
Signal acquisition part is by PD Acquisition Circuit (3000), current/voltage converter circuit (3001), low-pass filter (3002), same to phase
Amplifier (3003) and analog to digital conversion circuit (3004) are formed.
FPGA controller (2000) sends 24 sinusoidal sequences of fixed frequency all the way to 24 digital-to-analogue conversion cores by DDS
The sinusoidal signal of piece (2001), generated fixed frequency is selected by voltage/current conversion circuit (2002) in certain frequency
Reference luminous point light source (2004) and exciting light point light source (2005) are lighted under the gating of device (2003) respectively.
PD sensor (3000) is converted to collected optical signal after electric signal through overcurrent voltage conversion circuit
(3001) sinusoidal signal under fixed frequency is obtained, is filtered by low-pass filter (3002) and amplifier in the same direction (3003)
And signal shaping, it is input to analog-digital converter (3004) and is followed by FPGA controller (2000) completion signal processing.
The power module (1001) is used to be powered dissolved oxygen acquisition and main control module (1000).
The serial port module (1002) is communicated using RS-485 mode and computer (1100), send in real time and
Receive pretreated dissolved oxygen data.
The FPGA controller (2000) is used to export the sinusoidal signal that 24 sinusoidal sequences generate fixed frequency, and right
Calculated result is sent to calculating by serial port module (1002) after the data progress FFT calculating that analog-digital converter (3004) obtains
Machine (1100).
The digital analog converter (2001) uses 24 high-precision AD conversion chips, is used for FPGA controller (2000)
24 sinusoidal sequences of output are converted to the sinusoidal waveform of fixed frequency, retransmit to voltage/current conversion circuit (2002).
The voltage/current conversion circuit (2002) is built by double operational, is controlled by control transfer resistance resistance value
Size of current, when transfer resistance is set as R, input voltage U, output electric current is I=U/R.Output electric current is accessed into selector
Circuit (2003) input pin.
The selector circuit (2003) drives LED point light source for gating, and is controlled by FPGA controller (2000),
650nm wavelength reference light point light source of single (2004) and 395nm wavelength exciting light are respectively driven with certain frequency using input current
Point light source of single (2005).
The point light source is divided into the reference source (2004) of 650nm and the excitation light source (2005) of 395nm, molten according to PD
The absorption and reflection characteristic to light sources with different wavelengths of oxygen film (1012), reference source (2004) can directly reflect on film, instead
It penetrates light and reaches PD sensor (3000) by optical filter/convex lens (1013).Excitation light source (2005) is by PD dissolved oxygen film (1012)
Fluorescence is issued after absorption reaches PD sensor (3000) by optical filter/convex lens (1013).
The PD Acquisition Circuit (3000), will for the reference source (2004) and fluorescence of reflection to be acquired and converted
Optical signal is converted to electric signal, and the form of expression is current signal.The signal be input in current/voltage converter circuit (3001) into
Row conversion.
The low-pass filter (3002) and in-phase amplifier (3003) be used for obtained signal be filtered with it is whole
Shape meets analog-digital converter (3004) input requirements.
The analog-digital converter (3004) uses 24 bit resolution high-precision AD conversion chips, for the sampling to signal,
Sample frequency is 48MHz, meets Sampling Theorem greater than signal frequency 2 times or more.
The computer (1100) includes parameter setting module (1101), data processing module (1102), data display mould
Block (1103), data storage module (1104), parameter designing module (1101) is mainly to the sine wave freuqency of transmission, reference source
The parameters such as control frequency are gated with excitation light source to be controlled；Data processing module (1102) completion connects FFT calculated result
It receives, and calculates the phase at two paths of signals setting frequency point, and then obtain phase difference；Data disaply moudle (1103) is used for logarithm
According to phase difference and each signal phase real-time display；The phase for the two paths of signals that data storage module (1104) will acquire
Potential difference and the independent phase of each signal are saved in a manner of EXCEL.
The parameter setting module (1101) complete to salinity water to be measured, air pressure, etc. parameters be configured, and according to setting
Parameter complete dissolved oxygen content compensation
The data processing (1102) is broadly divided into two parts, and first part is dissolved oxygen content calculating, second part
For dissolved oxygen content calibration.Computer (1100) receives the FFT calculated result of serial port module (1002) transmission, for receiving
The real and imaginary parts data of each frequency point.Setting sample rate is f, and FFT points are a point, then carries out the frequency resolution after FFT
Are as follows:
And carrying out the corresponding frequency of N point after FFT is f1* (N-1) KHz, therefore be f at F frequency1* (F-1) KHz point.
Only need to calculate separately the phase of this point in reference light and fluorescence FFT calculated result, reference can be acquired by subtract each other
Phase difference between light and fluorescence sinusoidal signal.
Dissolved oxygen concentration is not only related with temperature, and related with the content of air pressure, salinity.Parameter setting and data school
Positive module mainly completes the setting of measurement parameter and the correction display function of dissolved oxygen concentration.
After the phase difference for obtaining reference light and fluorescence, the concentration of dissolved oxygen is calculated according to saturated dissolved oxygen solution formula
Value, while according to experimental calibration as a result, the calculated result to oxyty carries out salinity compensation.
p、poRespectively actual measurement and standard atmospheric pressure, unit Kpa；T is the temperature of saturated dissolved oxygen water body, and unit is
℃。
Computer host computer flow chart is as shown in Figure 4.
The data show that (1103) are divided into two parts, and first part is phase difference display figure, and second part is dissolution
Oxygen figure is shown.The wherein currently practical phase difference variation of phase difference display portion real-time display, dissolved oxygen display portion real-time display
The dissolved oxygen content of current detection water quality.
The online dissolved oxygen sensing instrument is directly anchored to certain depth in actual measurement content of oxygen dissolved in water
In water, the data that lower computer system collects are transmitted in upper computer module by RS-485 bus mode completes real time data
Processing and display, upper and lower computer are attached by shielded cable.
The online dissolved oxygen sensing system based on Fluorimetric Quenching Method of the present embodiment, by FPGA combination FFT method to ginseng
Phase difference than light and exciting light is detected, and measures the variation of fluorescence lifetime indirectly, and complete to water medium temperature by sensor
The advantages of degree and Simultaneous Pressure data acquire, make full use of hardware design guarantees light using the design method of single channel circuit
External disturbance suffered by source circuit is consistent, promotes detection accuracy；FPGA can be completed faster pair using parallel computation in the design
The processing of data further increases detection speed.Final dissolved oxygen content is calibrated using temperature and pressure testing result,
Obtain more accurate dissolved oxygen value.
As shown in figure 4, a kind of process of the online dissolved oxygen sensing system based on Fluorimetric Quenching Method are as follows:
(1) system power supply, system starts are carried out by power module (1001)
(2) FPGA (2000) generates 1 tunnel sinusoidal sequence and is input to the sine for generating certain frequency in D/A converter (2001)
Waveform, obtained sine wave are converted to current signal by V/I conversion circuit (2002), are respectively driven by selector (2003)
Reference light (2004) and exciting light (2005) LED.
(3) point light source generated gets to PD dissolved oxygen film (1012), dissolved oxygen film (1012) after through optical-fibre channel (1011)
Reflection 650nm reference light simultaneously absorbs 395nm exciting light, according to fluorescent quenching after dissolved oxygen film (1012) absorb 395nm exciting light
The principle of method generates 650nm wavelength fluorescent.The reference light of reflection and the fluorescence of generation pass through optical filter and convex lens (1013)
Into PD sensor (3000)
(4) current signal that PD sensor (3000) obtains is converted into voltage signal by I/V conversion circuit, through filtering
Wave device (3002) and amplifier (3003) circuit are input in AD (3004), are converted into digital signal and are input in FPGA (2000)
Carry out operation.
(5) FPGA (2000) run fft algorithm two-way sinusoidal signal is handled, after FFT is calculated result it is synthermal,
Pressure sensor sampled result is input in computer (1100) by serial port module (1002).
(6) parameter setting (1101) and data processing (1102) are carried out in computer (1100), and FFT calculated result is turned
It is changed to phase difference, and the dissolved oxygen content of current water quality is obtained with the relationship of dissolved oxygen content according to phase difference.
(7) dissolved oxygen content that previous step obtains obtains to the end after combining obtained temperature and pressure value to be corrected
Dissolved oxygen content value, the current phase difference variation of real-time display and dissolved oxygen content on simultaneous computer, so as to real-time monitoring.
Above embodiment is the preferable embodiment of the present invention, but embodiments of the present invention are not by the embodiment
Limitation, it is other it is any without departing from the spirit and principles of the present invention made by modification, substitution, combination, cut, should all
For equivalent substitute mode, it is included within the scope of the present invention.
Claims (7)
1. a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method, it is characterised in that: the system comprises slave computers
System and upper computer module, the lower computer system acquires for realizing data, fft algorithm processing, system controls, temperature is read
And data after pretreatment are sent to upper computer module, to facilitate the data transmission and control of computer (1100) and modules
System；Computer (1100) is handled for further to collected information, finally obtains required content of oxygen dissolved in water
And part relevant parameter, and real-time display testing result.
2. a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method as described in claim 1, it is characterised in that: institute
The lower computer system stated includes dissolved oxygen acquisition and main control module (1000), Metal shielding shell (1010), optical-fibre channel
(1011), PD high temperature dissolved oxygen film (1012) and convex lens/optical filter (1013) are pressed by dissolved oxygen acquisition and main control module (1000)
Launch 650nm reference light (2004) and 395nm exciting light (2005) according to certain frequency to get to by optical-fibre channel (1011)
Fluorescent quenching reaction, the reflected light and 395nm exciting light of 650nm reference light (2004) occur on PD high temperature dissolved oxygen film (1012)
(2005) fluorescence generated on dissolved oxygen film (1012) passes through convex lens/optical filter (1013) collected and control module respectively
(1003) the PD Acquisition Circuit (3000) on is acquired.
3. a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method as claimed in claim 2, which is characterized in that institute
The metal shielding (1010) stated is used to be electromagnetically shielded and provide the water-proof function of system to total system, meets certain
Testing requirements in the water of depth；
The optical-fibre channel (1011) ensure that 650nm reference light (2004) in acquisition and control module (1003) and
395nm exciting light (2005) can lossless arrival PD high temperature dissolved oxygen film (1012), and by the channel by control section and
High-temperature water is isolated, to realize that high-temperature water dissolved oxygen content detects；
The convex lens and optical filter (1013) are used to generate 650nm reference light (2004) and 395nm exciting light (2005)
Reflected light and fluorescence converged and filtered out heterogeneous light, guarantee that the light passed through is the light of single wavelength, further ensure and be
The detection accuracy of system；
Dissolved oxygen acquisition and main control module (1000) include power module (1001), serial port module (1002) and acquisition and
Control module (1003), the acquisition and control module (1003) are divided into two parts, and signal generates first part and controlled by FPGA
Device (2000) processed, digital analog converter (2001), voltage/current conversion circuit (2002), selector circuit (2003), 650nm wave
Long reference light point light source of single (2004), 395nm wavelength exciting light point light source of single (2005) composition；Signal acquisition part is acquired by PD
Circuit (3000), current/voltage converter circuit (3001), low-pass filter (3002), in-phase amplifier (3003) and modulus turn
Circuit (3004) is changed to be formed；
FPGA controller (2000) sends 24 sinusoidal sequences of fixed frequency all the way to 24 analog-digital chips by DDS
(2001), the sinusoidal signal of generated fixed frequency is by voltage/current conversion circuit (2002) in certain frequency selector
(2003) reference luminous point light source (2004) and exciting light point light source (2005) are lighted under gating respectively.PD sensor (3000) will
Collected optical signal, which is converted to the sine obtained under fixed frequency after electric signal through overcurrent voltage conversion circuit (3001), to be believed
Number, by low-pass filter (3002) and amplifier in the same direction (3003) is filtered and signal shaping, is input to analog-digital converter
(3004) FPGA controller (2000) are followed by and complete signal processing；
Power module (1001) is used to be powered dissolved oxygen acquisition and main control module (1000)；
Serial port module (1002) is communicated using RS-485 mode and computer (1100), sends and receives pretreatment in real time
Dissolved oxygen data afterwards.
4. a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method as described in one of claims 1 to 3, feature
It is, the FPGA controller (2000) is used to export the sinusoidal signal that 24 sinusoidal sequences generate fixed frequency, and to mould
Calculated result is sent to computer by serial port module (1002) after the data progress FFT calculating that number converter (3004) obtains
(1100)；
The digital analog converter (2001) uses 24 high-precision AD conversion chips, for exporting FPGA controller (2000)
24 sinusoidal sequences be converted to the sinusoidal waveform of fixed frequency, retransmit to voltage/current conversion circuit (2002)；
The voltage/current conversion circuit (2002) is built by double operational, controls electric current by control transfer resistance resistance value
Size, when transfer resistance is set as R, input voltage U, output electric current is I=U/R, and output electric current is accessed selector circuit
(2003) input pin；
The selector circuit (2003) is controlled, application for gating driving LED point light source by FPGA controller (2000)
Input current respectively drives 650nm wavelength reference light point light source of single (2004) and 395nm wavelength exciting light single-point with certain frequency
Light source (2005)；
The point light source is divided into the reference source (2004) of 650nm and the excitation light source (2005) of 395nm, according to PD dissolved oxygen film
(1012) the absorption and reflection characteristic to light sources with different wavelengths, reference source (2004) can directly reflect on film, reflected light
PD sensor (3000) are reached by optical filter/convex lens (1013).Excitation light source (2005) is absorbed by PD dissolved oxygen film (1012)
Fluorescence is issued afterwards reaches PD sensor (3000) by optical filter/convex lens (1013)；
The PD Acquisition Circuit (3000) believes light for the reference source (2004) and fluorescence of reflection to be acquired and converted
Number electric signal is converted to, the form of expression is current signal.The signal, which is input in current/voltage converter circuit (3001), to be turned
It changes；
The low-pass filter (3002) and in-phase amplifier (3003) is used to be filtered obtained signal and shaping, full
Sufficient analog-digital converter (3004) input requirements；
The analog-digital converter (3004) uses 24 bit resolution high-precision AD conversion chips, for the sampling to signal, sampling
Frequency is 48MHz, meets Sampling Theorem greater than signal frequency 2 times or more.
5. a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method as described in one of claims 1 to 3, feature
It is, the computer (1100) includes parameter setting module (1101), data processing module (1102), data disaply moudle
(1103) and data storage module (1104), parameter designing module (1101) to the sine wave freuqency of transmission, reference source and swashs
Light emitting source gating control frequency parameter is controlled；Data processing module (1102) completes the reception to FFT calculated result, and counts
The phase at two paths of signals setting frequency point is calculated, and then obtains phase difference；Data disaply moudle (1103) is used for the phase to data
The phase real-time display of potential difference and each signal；Dissolved oxygen content before the correction that data storage module (1104) will acquire
Dissolved oxygen content value, the phase difference of two paths of signals and the independent phase of each signal are protected in a manner of EXCEL after value, correction
It deposits.
6. a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method as described in one of claims 1 to 3, feature
It is, the parameter setting unit (1101) completion is configured salinity water to be measured, pneumatic parameter, and according to setting
Parameter complete dissolved oxygen content compensation；
The data processing unit (1102) is main to be divided into two parts, and first part is dissolved oxygen content calculating, and second part is
Dissolved oxygen content calibration, computer (1100) receive the FFT calculated result of serial port module (1002) transmission, every for receiving
The real and imaginary parts data of one frequency point, setting sample rate are f, and FFT points are a point, then carry out the frequency resolution after FFT
Are as follows:
And carrying out the corresponding frequency of N point after FFT is f1* (N-1) KHz, therefore be f at F frequency1* (F-1) KHz point only needs
Calculate separately in reference light and fluorescence FFT calculated result this point phase, subtract each other can acquire reference light and
Phase difference between fluorescence sinusoidal signal；
After the phase difference for obtaining reference light and fluorescence, the concentration value of dissolved oxygen is calculated according to saturated dissolved oxygen solution formula,
Simultaneously according to experimental calibration as a result, the calculated result to oxyty carries out salinity compensation；
p、poRespectively actual measurement and standard atmospheric pressure, unit Kpa；T is the temperature of saturated dissolved oxygen water body, and unit is DEG C；
The data display unit (1103) is divided into two parts, and first part is phase difference display figure, and second part is dissolution
Oxygen figure shows that wherein the currently practical phase difference of phase difference display portion real-time display changes, dissolved oxygen display portion real-time display
The dissolved oxygen content of current detection water quality.
7. a kind of online dissolved oxygen sensing system based on Fluorimetric Quenching Method as shown in one of claims 1~3, special
Sign is that the online dissolved oxygen sensing instrument is directly anchored to the water of certain depth in actual measurement content of oxygen dissolved in water
In, the data that lower computer system collects are transmitted in upper computer module by RS-485 bus mode to be completed at real time data
Reason and display, upper and lower computer are attached by shielded cable.
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