CN104155315B - The detection device and method of on-line measurement grain moisture content based on radio frequency transmission - Google Patents
The detection device and method of on-line measurement grain moisture content based on radio frequency transmission Download PDFInfo
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- CN104155315B CN104155315B CN201410407423.5A CN201410407423A CN104155315B CN 104155315 B CN104155315 B CN 104155315B CN 201410407423 A CN201410407423 A CN 201410407423A CN 104155315 B CN104155315 B CN 104155315B
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Abstract
The invention discloses the detection device and method of a kind of on-line measurement grain moisture content based on radio frequency transmission, including: detection antenna, high-frequency circuit and low-frequency channel；High-frequency circuit includes the signal generator producing radiofrequency signal, signal generator connects power splitter, power splitter has measurement signal output and local oscillation signal delivery outlet, measure signal output and connect the signal input part measuring antenna, local oscillation signal delivery outlet connects demodulator, and the signal output part measuring antenna connects demodulator；Low-frequency channel includes the signal amplifier being connected with demodulator, connects the microcontroller circuit of signal amplifier, and microcontroller circuit connects display circuit.This detection measurement device wide ranges, certainty of measurement is high, can reach 0.5% even 0.1%, owing to radiofrequency signal has penetrability, not being affected by moisture distribution so measuring, both can survey the moisture content on grain surface, it is also possible to surveys the moisture content in grain.
Description
Technical field
The present invention relates to grain moisture content detection technical field, especially, relate to the detection device and method of a kind of on-line measurement grain moisture content based on radio frequency transmission.
Background technology
Grain, before transaction or storing, is required for detecting the moisture content of grain, and needs to meet country or relevant unit's requirement to moisture content.Grain in order to make moisture content exceed standard reduces moisture content, needs to apply grain drying device to be recycled drying and processing, until it reaches requirement.In order to understand the situation of change of grain moisture content in dryer equipment in real time, and shut down in time after reaching water content requirement, it is necessary in real time grain moisture content is measured detection online.
The online detection instrument of domestic and international application is broadly divided into and rolls measuring resistance method and capacitance method at present.Rolling measuring resistance method is to be flattened by grain by rolling gear, then measures its moisture content by the resistance measurement principle between two gears.Having an advantage in that after cereal crops are rolled can measure within cereal crops aqueous, but a disadvantage is that structure is the most complicated, operation bothers very much.Owing to the individual size of different cereal crops there are differences, such as corn is more much bigger than millet, so also needing to regulation and rolls gear distance, if adjusting bad, directly affecting certainty of measurement.Additionally after time length, on gear, meeting incrustation, more have impact on the precision of measurement.
Capacitance method is to utilize to there is certain electric capacity between two parallel electrodes, and capacitance is affected by the dielectric constant of medium between two electrodes, thus the moisture content of medium is calculated by measuring electric capacity, this method is simple, but certainty of measurement is the lowest, and to the surface of cereal crops containing water sensitive, and to internal aqueous insensitive, the biggest measure error can be caused.Capacitance is not a linear corresponding relation with moisture content, and in the range of High water cut section, the change of capacitance is the most small, therefore capacitance measurement aqueous can only low aqueous under conditions of use.
Summary of the invention
Present invention aim at providing the detection device and method of a kind of on-line measurement grain moisture content based on radio frequency transmission, to solve in prior art, grain moisture content detection device structure is complicated, accuracy of detection problem the most rambunctious.
For achieving the above object, the present invention provides the detection device of a kind of on-line measurement grain moisture content based on radio frequency transmission, including: detection antenna, high-frequency circuit and low-frequency channel；High-frequency circuit includes the signal generator producing radiofrequency signal, signal generator connects power splitter, power splitter has measurement signal output and local oscillation signal delivery outlet, measure signal output and connect the signal input part measuring antenna, local oscillation signal delivery outlet connects demodulator, and the signal output part measuring antenna connects demodulator；Low-frequency channel includes the signal amplifier being connected with demodulator, connects the microcontroller circuit of signal amplifier, and microcontroller circuit connects display circuit.
Further, detection antenna includes metal shell, is provided with two pieces of metal baffle in metal shell; one nonmetallic antenna protection plate is set between two pieces of metal baffle; the side arrangement antenna of antenna protection plate, one end of antenna connects power splitter, and the other end connects demodulator.
Further, metal baffle is consistent with the shape of antenna protection plate.
Further, metal baffle and one end shape at an acute angle of antenna protection plate.
Further, antenna protection plate is polyimide plate or PVC(Polyvinyl chloride polymer, polyvinyl chloride) plate.
Further, signal generator is active crystal oscillator；Or, for DDS(Direct Digital Synthesizer, Direct Digital Synthesizer) and signal generator, DDS signal generator connects microprocessor.
Further, the frequency range of the radiofrequency signal of signal generator output is 125MHz-350MHz.
Further, the intensity the measuring signal local oscillation signal more than the output of local oscillation signal delivery outlet measuring signal output output of power splitter.
Further, demodulator is IQ phase discriminator or width phase demodulator；Microcontroller circuit is provided with communication interface.
The present invention also provides for a kind of method using above-mentioned detection device on-line measurement grain moisture content, comprises the following steps:
First, anhydrous phase difference P0 and pure water phase difference P1 is demarcated in advance:
Anhydrous phase difference P0 measures obtained phase difference in normal circumstances by detection device, is defined as the standard value of aqueous 0%；
Pure water phase difference P1 measures, by detection device, the phase difference obtained under water environment, is defined as the standard value of aqueous 100%；
Then, by detection device, detected medium is measured, obtain the RF phse difference X of detected medium；Then, according to formula: detected media water-bearing rate u=(x-P0)/(P1-P0) calculate detected media water-bearing rate.
The method have the advantages that
1, simple in construction, installs and easy for operation.
2, measure wide ranges, all can effectively measure in the range of 0-100%, and there is equal precision.
3, certainty of measurement is high, can reach 0.5% even 0.1%.
4, due to radiofrequency signal, there is penetrability, not affected by moisture distribution so measuring, both can survey the moisture content on grain surface, it is also possible to survey the moisture content in grain.
Accompanying drawing explanation
Below with reference to figure, the present invention is further detailed explanation.The accompanying drawing of the part constituting the application is used for providing a further understanding of the present invention, and the schematic description and description of the present invention is used for explaining the present invention, is not intended that inappropriate limitation of the present invention.In the accompanying drawings:
Fig. 1 is the theory diagram of the detection device preferred embodiment of present invention on-line measurement based on radio frequency transmission grain moisture content；
Fig. 2 be present invention on-line measurement based on radio frequency transmission grain moisture content detection device preferred embodiment in the theory diagram of signal generator embodiment one；
Fig. 3 be present invention on-line measurement based on radio frequency transmission grain moisture content detection device preferred embodiment in the theory diagram of signal generator embodiment two；
Fig. 4 be present invention on-line measurement based on radio frequency transmission grain moisture content detection device preferred embodiment in the theory diagram of power splitter；
Fig. 5 be present invention on-line measurement based on radio frequency transmission grain moisture content detection device preferred embodiment in measure the generalized section of antenna；
Fig. 6 be present invention on-line measurement based on radio frequency transmission grain moisture content detection device preferred embodiment in measure the front schematic view of antenna；
Fig. 7 be present invention on-line measurement based on radio frequency transmission grain moisture content detection device preferred embodiment in the theory diagram of demodulator embodiment one；
Fig. 8 be present invention on-line measurement based on radio frequency transmission grain moisture content detection device preferred embodiment in the theory diagram of demodulator embodiment two；
Fig. 9 be present invention on-line measurement based on radio frequency transmission grain moisture content detection device preferred embodiment in the theory diagram of microcontroller circuit.
Description of reference numerals:
100, detection antenna；200, high-frequency circuit；300, low-frequency channel；101, metal shell；102, metal baffle；103, antenna protection plate；104, antenna；201, signal generator；202, power splitter；203, demodulator；301, microcontroller circuit；302, signal amplifier；303, display circuit；304, communication interface.
Detailed description of the invention
Below in conjunction with accompanying drawing, embodiments of the invention are described in detail.
Referring to Fig. 1, Fig. 4 and Fig. 9, the preferred embodiments of the present invention provide the detection device of a kind of on-line measurement grain moisture content based on radio frequency transmission, including: detection antenna 100, high-frequency circuit 200 and low-frequency channel 300；High-frequency circuit 200 includes the signal generator 201 producing radiofrequency signal, signal generator 201 connects power splitter 202, power splitter 202 has measurement signal output and local oscillation signal delivery outlet, measure signal output and connect the signal input part measuring antenna 100, local oscillation signal delivery outlet connects demodulator 203, and the signal output part measuring antenna 100 connects demodulator 203；Low-frequency channel includes the signal amplifier 302 being connected with demodulator 203, connects the microcontroller circuit 301 of signal amplifier 302, and microcontroller circuit 301 connects display circuit 303.
The detection device of the on-line measurement grain moisture content based on radio frequency transmission that this preferred embodiment provides, it is as follows that it implements process:
When detecting, signal generator 201 producing high frequency radio signals, radiofrequency signal is divided into two-way by power splitter 202, and a road inputs to demodulator 203 as local oscillation signal；Another road, as measuring signal by detection antenna 100 through measured medium, is then input to demodulator 203；Demodulator 203 exports two-way direct current signal to signal amplifier 302, signal amplifier 302 carries out LPF amplification to this two-way direct current signal, and deliver to microcontroller circuit 301 and carry out analog-to-digital conversion, obtain the low frequency phase difference of two signals, then by display circuit 303, measurement data is shown.The dielectric constant of the grain being dried itself is the highest, when in grain, moisture content is the highest, its dielectric constant reduces, owing to phase shift can be produced with the change of dielectric permittivity through the radiofrequency signal of measured grain, it is possible to obtained the numerical value of the moisture content of correspondence by the phase difference of detection measurement signal and local oscillation signal.This structure of the detecting device is simple, installs and easy for operation.Measure wide ranges, all can effectively measure in the range of 0-100%, and there is equal precision, 0.5% even 0.1% can be reached.Owing to radiofrequency signal has penetrability, not affected by moisture distribution so measuring, both can be surveyed the moisture content on grain surface, it is also possible to surveyed the moisture content in grain.
Refer to Fig. 5 and Fig. 6; detection antenna includes metal shell 101; two pieces of metal baffle 102 it are provided with in metal shell 101; one nonmetallic antenna protection plate 103 is set between two pieces of metal baffle 102; the side arrangement antenna 104 of antenna protection plate 103; one end of antenna 104 connects power splitter 202, and the other end connects demodulator 203.Metal baffle 102 is consistent with the shape of antenna protection plate 103.Metal baffle 102 and one end shape at an acute angle of antenna protection plate 103.Antenna protection plate 103 is polyimide plate or PVC board.Metal baffle 102 is consistent with the shape of antenna protection plate 103, it is therefore an objective to effectively ensure to be formed between antenna 104 and metal baffle 102 the loop of rf, so that it is guaranteed that measure the reliable and stable of signal.Metal baffle 102 and one end shape at an acute angle of antenna protection plate 103, it can be ensured that impurity (such as, straw) will not be tangled or cling measurement antenna.Antenna 104 is arranged in the side of nonmetallic materials antenna protection plate 103, and its purpose one is in order to avoid antenna 104 weares and teares, and is on the other hand the white space by fill antenna 104, avoids the impurity in grain (such as, straw) etc. to hang on antenna 104.The antenna protection plate 103 of protection antenna 104 can use polyimides or PVC material, insulating properties and intensity the highest.
Referring to 2 and Fig. 3, signal generator 201 can use active crystal oscillator；Can also use DDS signal generator, DDS signal generator connects microprocessor.Two kinds of signal generators are applied in different occasions.Active crystal oscillator volume is little, and rate-adaptive pacemaker is stable, but frequency and signal strength signal intensity are fixed and cannot be changed, so being suitably applied in batch production and equipment volume being required high occasion.DDS signal generator connects microprocessor, can be by microprocessor control break frequency or output signal strength, so being suitably applied in test or special measurement occasion.Simultaneously, the intensity of the radiofrequency signal measured selects to depend on the length limitation of antenna and the aqueous excursion of measured medium, measuring medium for grain, in an embodiment, the frequency range of the radiofrequency signal of signal generator 201 output is more preferred scheme between 125MHz-350MHz.During measurement, the signal of measuring measuring signal output output of power splitter 202 has certain decay during detection；Therefore, in actual measurement, the intensity measuring signal is greater than the local oscillation signal of (being slightly larger than) local oscillation signal delivery outlet output.
Referring to Fig. 1, Fig. 7 and Fig. 8, demodulator 203 can use IQ phase discriminator, it would however also be possible to employ width phase demodulator.Two-way input signal quadrature demodulation is become I road and Q road low-frequency d signal by IQ phase discriminator, then calculates Amplitude Ratio and phase signal by after microcontroller circuit sample conversion.Two-way input signal is directly demodulated a road Amplitude Ratio direct current signal and a road phase difference direct current signal by width phase demodulator (the width phase demodulator chip of AD8302 model).If in needs high-precision wide temperature use occasion, use IQ phase discriminator.Width phase demodulator is then used in common low cost occasion.It addition, microcontroller circuit 301 is provided with communication interface 304, by communication interface 304, this detection device can connect other external equipment or host computer.
The present invention also provides for a kind of method using above-mentioned detection device on-line measurement grain moisture content, comprises the following steps:
First, anhydrous phase difference P0 and pure water phase difference P1 is demarcated in advance:
Anhydrous phase difference P0 measures obtained phase difference in normal circumstances by detection device, is defined as the standard value of aqueous 0%；
Pure water phase difference P1 measures, by detection device, the phase difference obtained under water environment, is defined as the standard value of aqueous 100%；
Then, by detection device, detected medium is measured, obtain the RF phse difference X of detected medium；Owing to RF phse difference X becomes more satisfactory linear relationship with the moisture content of measured medium, therefore can be according to formula: detected media water-bearing rate u=(x-P0)/(P1-P0) calculate detected media water-bearing rate.
Detected media water-bearing rate u calculates in units of volume, if needing to draw the moisture content in units of quality, then calculates acquisition by the conventional density of various different mediums.
As can be seen from the above description, the above embodiments of the present invention achieve following technique effect:
This structure of the detecting device is simple, installs and easy for operation.Measure wide ranges, all can effectively measure in the range of 0-100%, and there is equal precision, 0.5% even 0.1% can be reached.Owing to radiofrequency signal has penetrability, not affected by moisture distribution so measuring, both can be surveyed the moisture content on grain surface, it is also possible to surveyed the moisture content in grain.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention；For a person skilled in the art, the present invention can have various modifications and variations.All within the spirit and principles in the present invention, any modification, equivalent substitution and improvement etc. made, should be included within the scope of the present invention.
Claims (9)
1. the detection device of an on-line measurement grain moisture content based on radio frequency transmission, it is characterised in that
Including:
Detection antenna, high-frequency circuit and low-frequency channel；
Described high-frequency circuit includes the signal generator producing radiofrequency signal, and described signal generator connects
Power splitter, described power splitter has measurement signal output and local oscillation signal delivery outlet, and described measurement is believed
Number delivery outlet connects the signal input part of described measurement antenna, and described local oscillation signal delivery outlet connects demodulation
Device, the signal output part of described measurement antenna connects described demodulator；
Described low-frequency channel includes the signal amplifier being connected with described demodulator, connects described signal and puts
The microcontroller circuit of big device, described microcontroller circuit connects display circuit；
Described detection antenna includes metal shell, is provided with two pieces of metal baffle in described metal shell,
One nonmetallic antenna protection plate is set between two pieces of described metal baffle, described antenna protection plate
Side arrangement antenna, one end of described antenna connects described power splitter, and the other end connects described demodulator.
The detection dress of on-line measurement grain moisture content based on radio frequency transmission the most according to claim 1
Put, it is characterised in that:
Described metal baffle is consistent with the shape of described antenna protection plate.
The detection dress of on-line measurement grain moisture content based on radio frequency transmission the most according to claim 2
Put, it is characterised in that:
Described metal baffle and one end shape at an acute angle of described antenna protection plate.
The detection dress of on-line measurement grain moisture content based on radio frequency transmission the most according to claim 1
Put, it is characterised in that:
Described antenna protection plate is polyimide plate or PVC board.
The detection dress of on-line measurement grain moisture content based on radio frequency transmission the most according to claim 1
Put, it is characterised in that:
Described signal generator is active crystal oscillator；Or, for DDS signal generator, described
DDS signal generator connects microprocessor.
The detection dress of on-line measurement grain moisture content based on radio frequency transmission the most according to claim 5
Put, it is characterised in that:
The frequency range of the described radiofrequency signal of described signal generator output is 125MHz-350MHz.
The detection dress of on-line measurement grain moisture content based on radio frequency transmission the most according to claim 6
Put, it is characterised in that:
The intensity measuring signal of the described measurement signal output output of described power splitter is more than described
The local oscillation signal of local oscillation signal delivery outlet output.
The detection dress of on-line measurement grain moisture content based on radio frequency transmission the most according to claim 1
Put, it is characterised in that:
Described demodulator is IQ phase discriminator or width phase demodulator；Described microcontroller circuit is provided with logical
Communication interface.
9. one kind uses the detection device on-line measurement grain as according to any one of claim 1-8 aqueous
The method of rate, it is characterised in that comprise the following steps:
First, anhydrous phase difference P0 and pure water phase difference P1 is demarcated in advance:
Described anhydrous phase difference P0 measures obtained phase place in normal circumstances by described detection device
Difference, is defined as the standard value of aqueous 0%；
Described pure water phase difference P1 measures the phase difference obtained under water environment by described detection device,
It is defined as the standard value of aqueous 100%；
Secondly, by described detection device, detected medium is measured, obtain detected medium
RF phse difference X；Then, according to formula: detected media water-bearing rate u=(X-P0)/(P1-P0)
Calculate detected media water-bearing rate.
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| CN104713891A (en) * | 2015-04-03 | 2015-06-17 | 江苏麦赫物联网科技有限公司 | Device and method for detecting content of moisture and temperature in grain depot by employing modular radio frequency induction electric field |
| CN104713892A (en) * | 2015-04-03 | 2015-06-17 | 江苏麦赫物联网科技有限公司 | Modularized radio-frequency sensing electric field oil storage tank water-containing liquid level detection device and method |
| CN107238609A (en) * | 2017-05-18 | 2017-10-10 | 孟敏 | Icing frosting detection device and method based on microwave |
| CN109470311B (en) * | 2018-12-17 | 2019-09-06 | 吉林大学 | A kind of double hidden probe-type silo grain multi-parameter RF on-line measuring device and detection methods |
| CN109459450B (en) * | 2018-12-26 | 2023-12-19 | 江苏麦赫物联网科技有限公司 | Water content and conductivity detection system and detection method |
| CN112198173A (en) * | 2020-09-22 | 2021-01-08 | 上海欧申科技有限公司 | Wireless monitoring device for measuring water content of logging drilling fluid and control method thereof |
| CN113504251A (en) * | 2021-08-13 | 2021-10-15 | 河南工业大学 | Grain moisture rapid detection method and system based on radio frequency signals |
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