CN109507391A - A kind of detection device of the heavy metal content in soil based on DDS - Google Patents
A kind of detection device of the heavy metal content in soil based on DDS Download PDFInfo
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- CN109507391A CN109507391A CN201811477885.9A CN201811477885A CN109507391A CN 109507391 A CN109507391 A CN 109507391A CN 201811477885 A CN201811477885 A CN 201811477885A CN 109507391 A CN109507391 A CN 109507391A
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- 239000002689 soil Substances 0.000 title claims abstract description 99
- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 45
- 238000001514 detection method Methods 0.000 title claims abstract description 42
- 238000005259 measurement Methods 0.000 claims abstract description 24
- 229910052751 metal Inorganic materials 0.000 claims description 46
- 239000002184 metal Substances 0.000 claims description 46
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
Abstract
The present invention provides a kind of detection devices with the entirely different detection heavy metal content in soil based on DDS of prior art principle, and the detection device includes: sensor, Direct Digital Synthesizer (Direct Digital Synthesizer, DDS), current sampler, voltage sample device, instrumentation amplifier, A/D converter, interface circuit, MCU, input equipment, temperature control modules, power module；The sensor is also built-in with electric heater and thermocouple；When detecting, the soil pattern collected is filled in sensor.The shape of the Cp-f curve of the soil pattern obtained by measurement, Tan (Delta)-f curve, can be finally inversed by heavy metal content in soil.
Description
Technical field
The present invention relates to a kind of detection devices of heavy metal content in soil based on DDS.
Background technique
Heavy metal pollution of soil refers to due to natural or heavy metal is brought into soil by mankind's activity, causes soil
Content of beary metal is apparently higher than background value and causes existing or potential assessing index, Environmental deterioration in earth
The phenomenon that.Heavy metal-polluted soil is from a wealth of sources, mainly includes the improper heap of atmospheric falling dust, sewage irrigation, industrial solid castoff
It sets, mining activities, pesticide and chemical fertilizer etc..All materials using heavy metal and containing heavy metal are being produced as the industry of raw materials for production
Heavy metal may be discharged in the process, if mishandling, will result in environmental pollution.
During prevention, monitoring, administering heavy metal pollution of soil, detection heavy metal content in soil is one extremely important
Link.The quantitative detecting analysis technology of heavy metal usually has: it is ultraviolet can spectrophotometry (UV), atomic absorption method (AAS), former
Sub- fluorescence method (AFS), inductively coupled plasma body method (ICP), X fluorescence spectrum (XRF), Inductively coupled plasma-mass spectrometry
(ICP-MS).In addition to the above methods, there are also spectroscopic methodology detections.Also some is analyzed using X fluorescence spectrum (XRF).
In these above-mentioned detection methods, used instrument and equipment is all more accurate, expensive, and volume is larger, and need to be
It is fixed after the installation and debugging of laboratory to use, it can not go out to carry use, when detecting heavy metal content in soil, require existing
After quarry sampling, pretreatment and dystopy detection and analysis that laboratory carries out later period complexity are delivered, it is not only time-consuming but also inconvenient, it is impossible to be used in
Field quick detection.
Need quickly detection, analysis heavy metal pollution of soil situation when, be badly in need of it is a kind of can be used in on-site test, side
Portable belt, inexpensive detecting instrument and detection method.
In another application for a patent for invention on the same day of present patent application, proposes one kind and be based on programmable signal
The detection device of the detection heavy metal content in soil of device includes sensor in the detection device, and programmable signal occurs
Device, current sampler, voltage sample device, instrumentation amplifier I, instrumentation amplifier V, A/D converter I (i.e. ADC-I), A/D conversion
Device V (i.e. ADC-V), interface circuit, MCU, input equipment, temperature control modules, power module.
Summary of the invention
It is of the existing technology in order to solve the problems, such as, the purpose of the present invention is to provide it is a kind of completely new, be totally different from
The detecting instrument and measurement method of the heavy metal content in soil of the prior art, the present invention also aims to present patent application
Another application for a patent for invention on the same day make further improvement, simplify the composition of detecting instrument, reduce cost, simplify design.
Realizing the specific technical solution of the object of the invention is:
A kind of detection device of the detection heavy metal content in soil based on DDS, comprising:
Sensor, Direct Digital Synthesizer (Direct Digital Synthesizer, DDS), current sample
Device, instrumentation amplifier, A/D converter, interface circuit, MCU (micro-control unit, MicroController Unit；MCU, also known as
For one chip microcomputer), input equipment, temperature controller, power module；The sensor is also built-in with electric heater and heat
Galvanic couple；Power module is MCU, sensor, Direct Digital Synthesizer, current sampler, instrumentation amplifier, A/D are converted
Device, interface circuit, input equipment, temperature controller provide electric energy；When detecting, the soil collected is filled in sensor
Sample；Current sampler is usually made of the small resistance of one and sensor series, wherein the resistance value of the small resistance is significant
Ground is less than the resistance value of soil pattern, and the resistance value of the small resistance is by depending on the accuracy that measures；
The input equipment is electrically connected to MCU, and the signal input part of Direct Digital Synthesizer is electrically connected to
MCU, the signal output end of Direct Digital Synthesizer are electrically connected to sensor, and current sampler electrically connects with sensor
It connects, the signal input part of current sampler and instrumentation amplifier is electrically connected, and the signal output end of instrumentation amplifier is electrically connected
To the input end of analog signal of A/D converter, the digital signal output end of A/D converter is electrically connected to by interface circuit
MCU；In some Direct Digital Synthesizers using table look-up device framework, the electricity of Direct Digital Synthesizer generation
The voltage value of signal, which also can be reversed, is transmitted to MCU；
The sensor includes the metal plate of a pair of parallel disc-shaped, is respectively connected with ac signal per a piece of metal plate
Input terminal, for being connected to the signal output end of Direct Digital Synthesizer；Electricity is also equipped with inside per a piece of metal plate
Heater and thermocouple, i.e., the described sensor is built-in, and there are two electric heater and two thermocouples；Electric heater and thermocouple are logical
It crosses lead to extend outside metal plate, electric heater and lead are electrically insulated with metal plate, i.e. electric heater and lead is equipped with
Insulating sleeve；Electric heater and thermocouple are connected to temperature control modules by lead, so that the temperature of soil pattern is detecting
When be maintained at by the preset temperature value of MCU；
Input equipment is used to input preset measurement parameter and detection instruction to MCU；
Direct Digital Synthesizer can receive MCU issue instruction, according to MCU issue instruction synthesis go out frequency and
Amplitude is by the preset ac signal of MCU；When detecting, presetting the ac signal generated is frequency f t variation, width at any time
The ac signal that value remains unchanged；
At any time, output AC voltage signal, that is, sensor both ends alternating current of Direct Digital Synthesizer
Pressure signal is generated by the instruction that MCU is issued；
In the Direct Digital Synthesizer for being not based on table look-up device framework, what Direct Digital Synthesizer generated
The voltage value of electric signal is instructed by MCU and is directly issued；It is interior in the Direct Digital Synthesizer for being not based on table look-up device framework
Portion includes D/A converter, filter etc., and D/A converter receives the digital value from the MCU ac voltage signal issued, will
It is converted to analog AC voltage signal, and after wave filter filters out high-frequency digital noise, exports analog AC voltage signal；
Therefore, it in subsequent measurement work, no longer needs to measure the voltage of the ac signal at sensor both ends,
MCU stores ac signal voltage value while issuing instruction to Direct Digital Synthesizer；In subsequent measurement work
In work, it is only necessary to which the current value of the ac signal of sensor and soil pattern is passed through in measurement；
Direct Digital Synthesizer exports the ac signal to the sensor, examines to soil pattern
It surveys；
When detecting, MCU is also issued to temperature controller and is instructed, and the electric heater built in sensor is made to work, and controls institute
The temperature value for stating sensor maintains preset value；
It exports after current sampler to instrumentation amplifier and amplifies by the ac current signal of sensor, then by
Amplified analog signal is converted to digital signal by A/D converter, obtains the number of the ac current signal by sensor
Value；The digital value of the ac current signal by sensor is transmitted to MCU by interface circuit in real time, real-time by MCU
Ground storage, width of the MCU also according to both ac voltage signals of ac current signal and sensor both ends for passing through sensor
Value, phase calculation obtain the apparent capacity real part Cp of soil pattern, apparent capacity imaginary part Cp ', loss tangent Tan
(Delta), it while by calculated result stores in real time；
When detecting the content of beary metal of soil pattern, by the apparent capacity real part-of the MCU soil pattern that will test
Frequency curve, that is, Cp-f curve, loss tangent-frequency curve, that is, Tan (Delta)-f curve make normalized, to process
Normalized curve carries out the identification of curvilinear characteristic degree, then in MCU in song in the Standard Curve Database that prestores in the memory that sets
Line makees Auto-matching operation, and the numerical value in reference standard curve library obtains the content of beary metal of soil pattern collected, described
Standard Curve Database record has the process normalizing of multiple pre- standard soil samples for first passing through content of beary metal that measurement obtains, different
Apparent capacity real part-frequency curve, that is, Cp-f curve, loss tangent-frequency curve, that is, Tan (the Delta)-f for changing processing are bent
Line.
Preferably, the sensor includes a pair of of parallel metal sheet, and a pair of of parallel metal sheet is thin discs shape；
Preferably, the size of the thin discs shape metal plate is Centimeter Level, with a thickness of grade；
Preferably, it is any to can be keyboard, button, touch screen for input equipment；
Two electric heaters can be electrically connected in series to temperature control modules, can also be electrically connected to temperature control in parallel
Molding block；
Micro-control unit (MicroController Unit；MCU), also known as one chip microcomputer (Smgle Chip
It Microcomputer) or single-chip microcontroller, is central processing unit (Central Process Unit；CPU frequency and specification)
Do appropriate reduction, and by the perimeter interfaces such as memory (memory), counter (Timer), USB, A/D conversion, UART, PLC, DMA,
Even LCD driving circuit all integrates the computer for forming chip-scale on a single chip, does different groups for different applications
Close control.
Each curve in Standard Curve Database, in routine work: use is ultraviolet can spectrophotometry (UV), atom
Absorption process (AAS), atomic fluorescence method (AFS), inductively coupled plasma body method (ICP), X fluorescence spectrum (XRF), inductive coupling etc.
When any method of ion mass spectrometry (ICP-MS) detects heavy metal in soil content, while being surveyed using technical solution of the present invention
Measure apparent capacity real part-frequency curve i.e. Cp-f curve, the loss tangent-frequency curve i.e. Tan of the soil pattern
(Delta)-f curve, Cp-f curve, Tan (Delta)-f curve and the corresponding heavy metal of the soil pattern that measurement is obtained
Type, content are recorded into Standard Curve Database.
Measuring principle of the invention is described below:
Solid dielectric is in the effect by external electrical field, it may occur that electric polarization effect is not overlapped with positive and negative charge centroid
Electric polarization mode show electricity role and influence；Wherein play a major role be bound charge (in solid matter just
Anion, the electron outside nucleus fettered by atomic nucleus).Electrode law of bound charge under the action of electric field inside solid dielectric
There are substantial connections with medium microstructure.
There are three electropolarized basic processes: the 1. distortion polarization of extranuclear electron cloud；2. positive and negative ion in molecule
(opposite) displacement polarization；3. the steering of the intrinsic electric moment of molecule polarizes.Under extraneous electric field action, the permittivity ε of medium is comprehensive
Close the macroscopic physical quantity that ground reflects these three microprocess；It is the function of ε (f) of frequency f.
Under the action of an external electric field, the charged defects in solid state medium jump to another balance position from an equilbrium position
It sets or ion vibrates back and forth in certain local, effect is equivalent to the steering of electric moment.It is some have it is strong ionic
The solid of (key), their static permittivity ε s is always more much bigger than the numerical value of n2, outside the contribution of deionization displacement polarization, difference
Exactly caused by the jump of charged defects under the action of an external electric field.It is situated between for the solid of existing defects (especially foreign ion)
For matter, under the action of an external electric field, not only there is electric polarization course, there is also conductance processes, show macroscopic view conduction electric current
Effect, loss tangent Tan (Delta) increase.
For the soil pattern by heavy metal pollution, since the quality of heavy metal ion is greater than other elements significantly
Ions/atoms, frequency response process of the ion of different quality in alternating electric field is there is apparent difference, in alternation electricity
During the frequency of field gradually rises, heavy metal ion becomes increasingly difficult to keep up with first the steering of applied alternating field, matter
It is such to measure bigger ion；And since heavy metal ion exists in the form of foreign ion in soil pattern, so that native
Earth sample, there is also being lost as caused by conduction electric current, shows electricresistance effect, soil pattern institute when by extra electric field
Impure ion is more, and leakage current is bigger, in test, shows as apparent capacity imaginary part Cp ', loss tangent Tan
(Delta) increase.
In the soil pattern by heavy metal pollution, type, the content of heavy metal significantly affect apparent capacity reality
Portion-frequency curve, that is, Cp-f curve, loss tangent-frequency curve, that is, Tan (Delta)-f curve shape, curve shape
Distortion degree, distortion occur position, embody the weight of the substance of heterogeneity in soil.
By the apparent capacity real part-frequency curve i.e. Cp-f curve, loss angle tangent for the soil pattern that experiment measurement obtains
Value-frequency curve, that is, Tan (Delta)-f curve shape, can be finally inversed by heavy metal content in soil.In inverting, soil weight
The order of accuarcy of tenor depends on the sample-rich degree of established Standard Curve Database.
The content that this specification is not described in detail belongs to the prior art well known to professional and technical personnel in the field.
Beneficial effects of the present invention:
Using technical solution of the present invention, compared with the existing technology, have the advantages that following significant:
Since detecting instrument can be made small in size, Portable belt, and test device there is no it is such as ultraviolet can spectrophotometric
Method (UV), atomic absorption method (AAS), atomic fluorescence method (AFS), inductively coupled plasma body method (ICP), X fluorescence spectrum
(XRF), accurate, the enervated component in Inductively coupled plasma-mass spectrometry (ICP-MS), is quite suitable for field condition and quickly examines
It surveys.
Due to taking to the normalized processing of test data, so that in front in step, without substituting into parallel metal sheet
Area, spacing come the dielectric constant that converts, also, even if when soil sample compresses between parallel metal sheet, no matter soil sample
The whether really completely dense space filled up between parallel metal sheet, even if apparent capacity can be brought there are some perforations, missing
The measured deviation of real part Cp, apparent capacity imaginary part Cp ', but after normalized, these influence all disappear, in subsequent number
According in processing, without considering the absolute size of these measured values, but the shape for the curve that measurement obtains need to be only considered.This point
Bring the convenience of measurement.
And it is ultraviolet can spectrophotometry (UV), atomic absorption method (AAS), atomic fluorescence method (AFS), inductive coupling etc. from
Daughter method (ICP), X fluorescence spectrum (XRF), in Inductively coupled plasma-mass spectrometry (ICP-MS) measuring technique, none is not needed
Accurate, careful pre-treatment work is carried out to sample, is also had in measurement work meticulous.
It quickly being detected in addition, being suitable for field condition just because of technical solution of the present invention, operation very simple is convenient,
So that monitoring efficiency greatly improves in efforts at environmental protection.
Electricity is omitted in the application in the technical solution of another application for a patent for invention on the same day relative to present patent application
The A/D converter of sampler, voltage amplifier, voltage signal is pressed, circuit structure is further simplified, and cost is dropped
It is low.
Detailed description of the invention
Fig. 1: the structure chart of the detection device of field quick detection heavy metal content in soil of the invention.
Fig. 2: the sensor in detection device of the invention, dotted line indicates two electric heaters built in sensor in figure.
The insulating sleeve that electric heater and lead are equipped with is not drawn into figure, temperature sensor is also not drawn into.
Fig. 3: the structure chart of the power module in detection device of the invention.
Specific embodiment
It is of the invention for ease of understanding, come specifically to introduce technical solution of the present invention below with reference to example.
As shown in Figure 1, a kind of detection device of the detection heavy metal content in soil based on DDS, comprising:
Sensor, Direct Digital Synthesizer (Direct Digital Synthesizer, DDS), current sample
Device, instrumentation amplifier, A/D converter, interface circuit, MCU (micro-control unit, MicroController Unit；MCU, also known as
For one chip microcomputer), input equipment, temperature controller, power module；The sensor is also built-in with electric heater and heat
Galvanic couple；Power module is MCU, sensor, Direct Digital Synthesizer, current sampler, instrumentation amplifier, A/D are converted
Device, interface circuit, input equipment, temperature controller provide electric energy；When detecting, the soil collected is filled in sensor
Sample；
The current sampler is usually made of the small resistance of one and sensor series, wherein the electricity of the small resistance
Resistance value is less than the resistance value (usually kilo-ohm magnitude) of soil pattern, such as several ohm significantly；
The input equipment is electrically connected to MCU, and the signal input part of Direct Digital Synthesizer is electrically connected to
MCU, the signal output end of Direct Digital Synthesizer are electrically connected to sensor, and current sampler electrically connects with sensor
It connects, the signal input part of current sampler and instrumentation amplifier is electrically connected, and the signal output end of instrumentation amplifier is electrically connected
To the input end of analog signal of A/D converter (i.e. ADC-I), the digital signal output end of A/D converter passes through interface circuit electricity
Property is connected to MCU；
The sensor includes the metal plate of a pair of parallel disc-shaped, is respectively connected with ac signal per a piece of metal plate
Input terminal, the signal for being connected to Direct Digital Synthesizer (Direct Digital Synthesizer, DDS) are defeated
Outlet；It is also equipped with electric heater and thermocouple inside per a piece of metal plate, i.e., the described sensor is built-in, and there are two electric heaters
With two thermocouples；Electric heater and thermocouple are extended outside metal plate by lead, and electric heater and lead are and metal plate
It is electrically insulated, i.e. electric heater and lead is equipped with insulating sleeve；Electric heater and thermocouple are connected to temperature control by lead
Molding block, so that the temperature of soil pattern is maintained at when detecting by the preset temperature value of MCU；
Input equipment is used to input preset measurement parameter and detection instruction to MCU；
Direct Digital Synthesizer (Direct Digital Synthesizer, DDS) can receive the finger that MCU is issued
It enables, goes out frequency and amplitude by the preset ac signal of MCU according to the instruction synthesis that MCU is issued；When detecting, generation is preset
Ac signal is the frequency f ac signal that t variation, amplitude remain unchanged at any time；
At any time, output AC voltage signal, that is, sensor both ends alternating current of Direct Digital Synthesizer
Pressure signal is generated by the instruction that MCU is issued；
Direct Digital Synthesizer (Direct Digital Synthesizer, DDS) is to be not based on table look-up device frame
The Direct Digital Synthesizer of structure, the voltage value for the electric signal that Direct Digital Synthesizer generates are instructed straight by MCU
Sending and receiving go out；Therefore, it in subsequent measurement work, no longer needs to measure the voltage of the ac signal at sensor both ends,
MCU stores ac signal voltage value while issuing instruction to Direct Digital Synthesizer；In subsequent measurement work
In work, it is only necessary to which the current value of the ac signal of sensor and soil pattern is passed through in measurement；
Direct Digital Synthesizer exports the ac signal to the sensor, examines to soil pattern
It surveys；
When detecting, MCU is also issued to temperature controller and is instructed, and the electric heater built in sensor is made to work, and controls institute
The temperature value for stating sensor maintains preset value；
It exports after current sampler to instrumentation amplifier and amplifies by the ac current signal of sensor, then by
Amplified analog signal is converted to digital signal by A/D converter, obtains the number of the ac current signal by sensor
Value；The digital value of the ac current signal by sensor is transmitted to MCU by interface circuit in real time, real-time by MCU
Ground storage, width of the MCU also according to both ac voltage signals of ac current signal and sensor both ends for passing through sensor
Value, phase calculation obtain the apparent capacity real part Cp of soil pattern, apparent capacity imaginary part Cp ', loss tangent Tan
(Delta), it while by calculated result stores in real time；
When detecting the content of beary metal of soil pattern, by the apparent capacity real part-of the MCU soil pattern that will test
Frequency curve, that is, Cp-f curve, loss tangent-frequency curve, that is, Tan (Delta)-f curve make normalized, to process
Normalized curve carries out the identification of curvilinear characteristic degree, then in MCU in song in the Standard Curve Database that prestores in the memory that sets
Line makees Auto-matching operation, and the numerical value in reference standard curve library obtains the content of beary metal of soil pattern collected, described
Standard Curve Database record has the process normalizing of multiple pre- standard soil samples for first passing through content of beary metal that measurement obtains, different
Apparent capacity real part-frequency curve, that is, Cp-f curve, loss tangent-frequency curve, that is, Tan (the Delta)-f for changing processing are bent
Line.
As shown in Fig. 2, the sensor includes the metal plate of a pair of parallel disc-shaped, it is respectively connected with per a piece of metal plate
Ac signal input terminal, respectively AC1 and AC2, for being connected to Direct Digital Synthesizer (Direct Digital
Synthesizer, DDS) signal output end；It is also equipped with electric heater inside per a piece of metal plate, i.e., in the described sensor
Electric heater there are two setting；Electric heater is extended outside metal plate by lead, and electric heater and lead are electrical with metal plate
Insulation, i.e. electric heater and lead are equipped with insulating sleeve；Electric heater is connected to temperature control modules by lead, so that native
The temperature of earth sample is maintained at when detecting by the preset temperature value of MCU；Described two electric heaters are respectively provided with lead end
Heater1 and Heater1-1, Heater2 and Heater2-2, when in use, lead end Heater1 can be with Heater2-2 electricity
Property links together, and Heater1-1 and Heater2 are electrically connected, and two electric heaters are connected in parallel
To temperature controller.
It is constituted as shown in figure 3, power module is aided with peripheral resistance capacitance element by MAX610 chip for core.
When using above-mentioned detection device to detect heavy metal content in soil, step approximately as:
Collection in worksite soil pattern；In acquisition, dead twigs and withered leaves, macroscopic gravel particle are removed；Soil pattern
Sampling quantity is several grams to ten grams, in this way, both measurement error will not be caused big because sample size is very little in measurement, it will not
Cause the electric energy of overlong time spent by heating, drying, consuming excessive because sample size is too big.Normally, to several grams to ten
Gram soil pattern amount for, in the state of compression carry out heating, drying to constant weight, generally require 3-5 minutes；
The soil pattern collected is pulverized, a pair that the soil pattern pulverized is placed directly in sensor is parallel
Apply pressure compaction between metal plate, scrapes off the redundance leaked out outside parallel metal sheet with scraping blade, be made and parallel metal sheet
Shape is identical, equal-sized laminar sample；
MCU issues heating instructions to temperature controller, and heating baking is carried out in the state of compression to the soil pattern of compacting
It does to constant weight；By soil pattern, drying to constant weight, is that the moisture in order to avoid containing in sample brings subsequent electrical measurement
Large error.The temperature of heating, drying is carried out in the state of compression between 110 DEG C -120 DEG C to the soil pattern of compacting.
Sweep check: at a constant temperature, Direct Digital Synthesizer (Direct Digital is utilized
Synthesizer, DDS) apply the continually changing alternate electrical signal vt work of a frequency on a pair of of parallel metal sheet of sensor
With on the soil pattern of drying, the frequency f of the output alternate electrical signal vt in the alternating signal source at any time t and change,
Signal amplitude then remains unchanged；Direct Digital Synthesizer (Direct Digital Synthesizer, DDS) is by MCU
The instruction of sending is controlled；In an example, Direct Digital Synthesizer (Direct Digital
Synthesizer, DDS) output alternate electrical signal vtFrequency f it is primary every 200ms variation, frequency increases from 100Hz, often
1.1 times are differed between two frequencies, until increasing to 1MHz or so, specific list of frequency is as follows:
100Hz, 110Hz, 121Hz, 133.1Hz ..., 777.88KHz, 855.67KHz, 941.23KHz, 1.035MHz,
98 Frequency points in total, 98 Frequency point tests are completed, and need time 49s in total.
Real-time detection simultaneously records the electrical parameter that the alternate electrical signal passes through above-mentioned a pair of of parallel metal sheet and soil pattern,
The electrical parameter includes the apparent capacity real part Cp of alternate electrical signal, apparent capacity imaginary part Cp ', loss tangent Tan
(Delta), frequency f；Wherein, loss tangent Tan (Delta) is equal to apparent capacity imaginary part Cp ' and apparent capacity real part Cp
Ratio；
MCU will test the obtained data of record, respectively export obtain apparent capacity real part-frequency curve i.e. Cp-f curve,
Loss tangent-frequency curve, that is, Tan (Delta)-f curve；It is bent in all apparent capacity real part-frequency curves, that is, Cp-f
In line, loss tangent-frequency curve, that is, Tan (Delta)-f curve, frequency takes logarithm, i.e. logf or lgf；It is described
The output alternate electrical signal v of Direct Digital Synthesizer (Direct Digital Synthesizer, DDS)tFrequency f
Down to Hz magnitude, up to MHz magnitude；The output alternate electrical signal v in alternating signal sourcetFrequency f t makees logarithmic parabola change at any time
Change；
Obtained apparent capacity real part-frequency curve is made normalized by MCU；Loss tangent Tan (Delta)-
Frequency f curve itself has been substantially nondimensional, normalized curve, without remaking normalized；
When detecting the content of beary metal of soil pattern, by the apparent capacity real part-of the MCU soil pattern that will test
Frequency curve, that is, Cp-f curve, loss tangent-frequency curve, that is, Tan (Delta)-f curve make normalized, to process
Normalized curve carries out the identification of curvilinear characteristic degree, then in MCU in song in the Standard Curve Database that prestores in the memory that sets
Line makees Auto-matching operation, and the numerical value in reference standard curve library obtains the content of beary metal of soil pattern collected, described
Standard Curve Database record has the process normalizing of multiple pre- standard soil samples for first passing through content of beary metal that measurement obtains, different
Apparent capacity real part-frequency curve, that is, Cp-f curve, loss tangent-frequency curve, that is, Tan (the Delta)-f for changing processing are bent
Line.In all apparent capacity real part-frequency curves, loss tangent-frequency curve, frequency takes logarithm, i.e. logf
Or lgf.In Standard Curve Database, each curve also has additional information, and the additional information includes: each by normalization
Apparent capacity real part-frequency curve of processing, all extreme points of loss tangent-frequency curve, first derivative curve
Zero point, the zero point of Second derivative curves；
Actual test temperature value is identical as the measurement temperature in Standard Curve Database.
According to our practical experience, in low-frequency range, the apparent capacity real part Cp- frequency f curve of sample, loss angle tangent
Value Tan (Delta)-frequency f curve usually changes more slowly, if t makees linear rule variation to frequency f at any time, from hundred Hz amounts
Grade will lead to time-consuming too long to million Hz magnitudes, be up to a few hours, and obtained data volume is too many, does not see obviously in low-frequency range
Variation；And select frequency f t makees logarithmic parabola variation at any time, then it takes only about 1 minute, change can be shown in each frequency band
Law.
When the result of detection be reported out heavy metal in soil content it is significantly exceeded when, mark the soil of the sampling section by weight
Metallic pollution, and using it is ultraviolet can spectrophotometry (UV), atomic absorption method (AAS), atomic fluorescence method (AFS), inductive coupling
Plasma method (ICP), X fluorescence spectrum (XRF), any method in Inductively coupled plasma-mass spectrometry (ICP-MS) carry out
Further heavy metal type identifies, content accurately measures.
Certainly, described above is only that presently preferred embodiments of the present invention is answered the present invention is not limited to enumerate above-described embodiment
When explanation, anyone skilled in the art is all equivalent substitutes for being made, bright under the introduction of this specification
Aobvious variant, all falls within the essential scope of this specification, ought to be by protection of the invention.
The content that this specification is not described in detail belongs to the prior art well known to professional and technical personnel in the field.
Express one's thanks to: the invention patent project is by " the research of ultra wide band and wearable antenna in wireless body area network
And " research (17KJA470007) of the self-assembling technique for flexible antennas and microwave integrated circuit " project (KFKT2016A05) "
The subsidy of fund, expresses thanks herein.
Claims (10)
1. a kind of detection device of heavy metal content in soil, which is characterized in that the detection device includes: sensor, amplifier,
A/D converter and one chip microcomputer；When detecting, the soil pattern collected is filled in sensor.
2. a kind of detection device of the heavy metal content in soil based on DDS, which is characterized in that the detection device includes:
Sensor, Direct Digital Synthesizer (Direct Digital Synthesizer, DDS), current sampler, instrument
With amplifier, A/D converter, interface circuit, MCU (micro-control unit, MicroController Unit；MCU, also known as singly
Piece microcomputer), input equipment, temperature controller, power module；The sensor is also built-in with electric heater and thermoelectricity
It is even；Power module be MCU, sensor, Direct Digital Synthesizer, current sampler, instrumentation amplifier, A/D converter,
Interface circuit, input equipment, temperature controller provide electric energy；When detecting, the soil examination collected is filled in sensor
Sample；
Direct Digital Synthesizer can receive the instruction that MCU is issued, and go out frequency and amplitude according to the instruction synthesis that MCU is issued
By the preset ac signal of MCU；When detecting, presetting the ac signal generated is that frequency f at any time protect by t variation, amplitude
Hold constant ac signal；
At any time, output AC voltage signal, that is, sensor both ends alternating voltage letter of Direct Digital Synthesizer
Number by MCU issue instruction generate；
The input equipment is electrically connected to MCU, and the signal input part of Direct Digital Synthesizer is electrically connected to MCU,
The signal output end of Direct Digital Synthesizer is electrically connected to sensor, and current sampler and sensor are electrically connected,
The signal input part of current sampler and instrumentation amplifier is electrically connected, and the signal output end of instrumentation amplifier is electrically connected to A/
The digital signal output end of the input end of analog signal of D converter, A/D converter is electrically connected to MCU by interface circuit；
Input equipment is used to input preset measurement parameter and detection instruction to MCU；
The sensor includes the metal plate of a pair of parallel disc-shaped, and ac signal input is respectively connected with per a piece of metal plate
End, for being connected to the signal output end of Direct Digital Synthesizer；
Direct Digital Synthesizer exports the ac signal to the sensor, detects to soil pattern；
When detecting, MCU is also issued to temperature controller and is instructed, and so that the electric heater built in sensor is worked, is controlled the biography
The temperature value of sensor maintains preset value；
It exports after current sampler to instrumentation amplifier and amplifies by the ac current signal of sensor, then by A/D
Amplified analog signal is converted to digital signal by converter, obtains the digital value of the ac current signal by sensor；
The digital value of the ac current signal by sensor is transmitted to MCU by interface circuit in real time, is deposited in real time by MCU
Storage, amplitude, phase of the MCU also according to both ac voltage signals of ac current signal and sensor both ends for passing through sensor
The apparent capacity real part Cp, apparent capacity imaginary part Cp ', loss tangent Tan (Delta) of soil pattern is calculated in position, together
When calculated result is stored in real time；
When detecting the content of beary metal of soil pattern, by apparent capacity real part-frequency of the MCU soil pattern that will test
Curve, that is, Cp-f curve, loss tangent-frequency curve, that is, Tan (Delta)-f curve make normalized, to by normalizing
The curve of change carries out the identification of curvilinear characteristic degree, then in MCU in curve in the Standard Curve Database that prestores in the memory that sets make
Auto-matching operation, the numerical value in reference standard curve library, obtains the content of beary metal of soil pattern collected, the standard
Curve library record has at the process normalization of multiple pre- standard soil samples for first passing through content of beary metal that measurement obtains, different
Apparent capacity real part-frequency curve, that is, Cp-f curve, the loss tangent-frequency curve, that is, Tan (Delta)-f curve of reason；
Wherein, Cp is the real part of the apparent capacity of soil pattern, and Tan (Delta) is the loss tangent of soil pattern, and f is
Frequency.
3. a kind of detection device of the heavy metal content in soil based on DDS as claimed in claim 2, it is characterised in that:
In the Direct Digital Synthesizer for being not based on table look-up device framework, inside includes D/A converter, filter, D/A
Converter receives the digital value from the MCU ac voltage signal issued, is converted into analog AC voltage signal, and pass through
After filter filters out high-frequency digital noise, analog AC voltage signal is exported.
4. a kind of detection device of the heavy metal content in soil based on DDS as claimed in claim 2, it is characterised in that: input
Equipment is keyboard, button, any in touch screen.
5. a kind of detection device of such as described in any item heavy metal content in soil based on DDS of claim 2-4, feature exist
In: in the soil pattern by heavy metal pollution, type, the content of heavy metal affect apparent capacity real part-frequency curve
That is Cp-f curve, loss tangent-frequency curve, that is, Tan (Delta)-f curve shape, the distortion degree of curve shape,
The position that distortion occurs, embodies the weight of the substance of heterogeneity in soil.
6. a kind of detection device of such as described in any item heavy metal content in soil based on DDS of claim 2-5, feature exist
In: it is also equipped with electric heater and thermocouple inside every a piece of metal plate of the sensor, i.e., the described sensor is built-in with two
A electric heater and two thermocouples；Electric heater and thermocouple are extended outside metal plate by lead, electric heater and lead
It is electrically insulated with metal plate, i.e. electric heater and lead is equipped with insulating sleeve；Electric heater and thermocouple are connected by lead
Temperature control modules are connected to, so that the temperature of soil pattern is maintained at when detecting by the preset temperature value of MCU.
7. a kind of detection device of such as described in any item heavy metal content in soil based on DDS of claim 2-6, feature exist
In: two electric heaters built in the sensor are electrically connected to temperature control modules in parallel.
8. a kind of detection device of such as described in any item heavy metal content in soil based on DDS of claim 2-7, feature exist
In: power module is aided with peripheral resistance capacitance element by MAX610 chip for core and constitutes.
9. a kind of detection device of such as described in any item heavy metal content in soil based on DDS of claim 2-8, feature exist
In: in Standard Curve Database, each curve also has additional information, and the additional information includes: each by normalization
Apparent capacity real part-frequency curve of reason, all extreme points of loss tangent-frequency curve, first derivative curve zero
The zero point of point, Second derivative curves.
10. a kind of detection device of the heavy metal content in soil based on DDS, it is characterised in that: the detection device includes: sensing
Device, amplifier, A/D converter and one chip microcomputer；When detecting, the soil collected is filled in sensor
Sample；The sensor includes the metal plate of a pair of parallel sheet, is respectively connected with the defeated of ac signal per a piece of metal plate
Enter end；The sensor is for measuring the Cp-f curve for obtaining soil pattern, Tan (Delta)-f curve, the soil obtained by measurement
Cp-f curve, Tan (Delta)-f curve of earth sample, are finally inversed by heavy metal content in soil；Wherein, Cp is the table of soil pattern
The real part of capacitor is seen, Tan (Delta) is the loss tangent of soil pattern, and f is frequency.
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Effective date of registration: 20230824 Address after: 226000 Jiangsu city of Nantong province sik Road No. 9 Patentee after: Nantong University Technology Transfer Center Co.,Ltd. Address before: 226019 Jiangsu Province, Nantong City Chongchuan District sik Road No. 9 Patentee before: NANTONG University |
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Application publication date: 20190322 Assignee: Nantong Hongjingtian Mechanical Equipment Technology Co.,Ltd. Assignor: Nantong University Technology Transfer Center Co.,Ltd. Contract record no.: X2023980049389 Denomination of invention: A DDS based detection device for soil heavy metal content Granted publication date: 20210406 License type: Common License Record date: 20231203 |