CN201527407U - Multipoint Soil Moisture Sensor - Google Patents

Abstract

The utility model provides a multi-point type soil water content sensor comprising a power supply unit, a communication unit, a control processing unit, a node selecting unit and a node unit, wherein the communication unit receives user instruction information including soil depth to be measured, sends the information to the control processing unit and receives water content measured data and feeds back the information to a user; the control processing unit sends the user instruction information to the node selecting unit and acquires and processes a frequency signal which is selected by the node selecting unit and outputted by the sensor node, acquires water measured data and outputs the water measured data to the communication unit; the node selecting unit selects and communicates corresponding sensor nodes in the node unit according to the user instruction information; and in the node unit, the node selected and communicated by the node unit carries out amplification, reshaping and frequency division on the high-frequency signal obtained by measurement, and then outputs the frequency signal acquired by the control processing unit. The multi-point type soil water content sensor has the characteristics of multi-point measurement, real-time waking, low power consumption and difficulty for being polluted and the like and can realize real-time measurement on the soil water content.

Description

The multipoint mode soil moisture sensor

Technical field

The utility model relates to field of measuring technique, particularly a kind of sensor that utilizes the dielectric constant measurement soil moisture of soil.

Background technology

The raising of agricultural modernization degree and the shortage of water resource are had higher requirement to the growing environment of crops, should guarantee the water demand of crops, can not cause the waste of water resource again, this just need develop the agriculture intelligent irrigation control system that is fit to the Different Crop needs, and the sensor of high precision, high stability and high reliability and the real-time measured soil moisture of energy is the assurance that agriculture intelligent irrigation control system is achieved.At present, widely used soil moisture sensor is based on spininess single-point type.But this class sensor is because there is certain limitation in the Structure Designing Problem of himself when measured soil moisture.Specifically, though this class sensor can be realized the real-time measurement of soil water content, owing in use must be buried in for a long time in the soil, its metal probe is perishable, will inevitably cause the decline of measuring accuracy; In addition, this class sensor can only fill order's point measurement, if system requirements is measured different depth of soil moisture, a plurality of these class soil moisture sensors just need be set, and this will bring very big difficulty to the laying of sensor; Moreover this class sensor generally is in the long-term work state, though the power consumption of single-sensor is little, a plurality of sensors will be accumulated and consume very big energy, be unfavorable for using under solar powered occasion.

The utility model content

The purpose of this utility model is the above-mentioned deficiency at prior art, provides a kind of and has multimetering, wakes up in real time, low-power consumption and specific multipoint mode soil moisture sensor such as not perishable, realizes the real-time measurement to soil moisture.

For realizing above-mentioned purpose of the present utility model, a kind of multipoint mode soil moisture sensor comprises:

Power supply unit is the whole sensor power supply;

Communication unit receives the user instruction information that comprises depth of soil to be measured, sends described information and feeds back to the user from its reception moisture measurement data and with described data to controlled processing unit;

Controlled processing unit sends to the node selected cell with described user instruction information, gathers and handle the frequency signal of selecting the sensor node of connection to export by described node selected cell, obtains the moisture measurement data, exports to communication unit;

The node selected cell is communicated with corresponding sensor node in the node unit according to the user instruction Information Selection from described controlled processing unit;

Node unit, comprise N the respectively sensor node of the corresponding different soils degree of depth, the node of being selected to be communicated with by described node selected cell will measure that the high-frequency signal that obtains amplifies, export the frequency signal that can be gathered by described controlled processing unit behind shaping and the frequency division; Wherein, N is not more than 8.

Further, also comprise timing unit, regularly send described user instruction information to described communication unit.

Wherein, described power supply unit is integrated chip ASM1117; Described communication unit is RS485 module or wireless module; Described controlled processing unit is singlechip chip C8051F930; Described node selected cell is chip CD4051.

Wherein, each described sensor node comprises: high frequency measurement circuit, amplifying circuit and plastic sub-frequency circuit.

Wherein, described high frequency measurement circuit is the LC oscillatory circuit that comprises annular capacitor.

Wherein, described annular capacitor is two stainless steel annulus that connect by insulating material.

Wherein, described amplifying circuit comprises the two poles of the earth amplifying circuit of series connection.

Wherein, described plastic sub-frequency circuit comprises chip SN74AHCT14 and SN74F161.

Wherein, a described N sensor node connects with preset distance successively by insulating medium.

Wherein, each described sensor node is made for circular.

Compared with prior art, the utlity model has following advantage:

1. can while measured soil section different depth of soil moisture.

2. the user can carry out the soil water content measurement by the required sensor node of timing wake-up, has reduced the power consumption of sensor greatly.

Description of drawings

Fig. 1 is the structural drawing according to multipoint mode soil moisture sensor of the present utility model;

Fig. 2 is the synoptic diagram according to the node unit of multipoint mode soil moisture sensor of the present utility model;

Fig. 3 is the annexation figure according to a sensor node medium-high frequency circuit of the node unit of multipoint mode soil moisture sensor of the present utility model;

Fig. 4 is the annexation figure according to amplifying circuit in the sensor node of the node unit of multipoint mode soil moisture sensor of the present utility model;

Fig. 5 is the annexation figure according to plastic sub-frequency circuit in the sensor node of the node unit of multipoint mode soil moisture sensor of the present utility model.

Embodiment

The multipoint mode soil moisture sensor that the utility model proposes is described as follows in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, comprise according to multipoint mode soil moisture sensor of the present utility model:

Power supply unit is each unit power supply of whole sensor; This power supply unit can be integrated linear power supply chip, and its output voltage ripple is little, the efficient height; Preferably, be integrated chip ASM1117.

Communication unit sends the user instruction information that comprises depth of soil to be measured to controlled processing unit, wakes controlled processing unit up; And reception feeds back to the user from the measurement data of controlled processing unit and with it; Particularly, described user instruction information can be the real-time information that the user sends, and realizes real-time soil moisture measurement; Also can be the timing information that sends by the timing unit (not shown), realize that the timing of timing wake-up and soil moisture is measured.Preferably, this communication unit can be RS485 module or wireless module.

Controlled processing unit, described user instruction information is sent to the node selected cell, gather frequency signal, described frequency signal is handled demarcation by the sensor node output of the selected connection of described node selected cell, obtain measurement data, export to communication unit; This controlled processing unit can be the single-chip microcomputer of low-power consumption, preferably, is super low power consuming single chip processor chip C8051F930.

The node selected cell is communicated with corresponding sensor node in the node unit according to the user instruction from controlled processing unit; This node selected cell can be selected chip for integrated multi-channel analog, preferably, is chip CD4051.

Node unit, the frequency signal that the high-frequency signal that obtains amplifies the sensor node that select to be communicated with by the node selected cell to measuring, output can the Be Controlled processing unit be gathered behind shaping and the frequency division.

Wherein, this node unit comprises a plurality of sensor nodes, each node corresponding respectively different depth of soil.As shown in Figure 2, the node unit of present embodiment comprises that being formed into circular sensor node 1, sensor node 2, sensor node 3 and 4, four nodes of sensor node connects with different intervals successively by the ring-type insulating medium.In fact, node can increase and decrease according to user's needs, but is no more than 8 at most; Internodal distance (being the length of ring-type insulating medium between adjacent node) also can customize.

Particularly, each sensor node comprises: high-frequency circuit, amplifying circuit and frequency dividing circuit.

As shown in Figure 3, be triode Q1 according to the high-frequency circuit of the sensor node of node unit of the present utility model by the 2N2222A model, resistance R 1, R2, R3, R4, capacitor C 1, C2, C3, C4, the LC oscillatory circuit that inductance L 1 and annular capacitor Cp form.Wherein, annular capacitor is made up of two stainless steel rings, isolates by insulating material between the annulus.Wherein, resistance R 1, R2, R3 and R4 provide suitable quiescent point for the LC oscillatory circuit; Capacitor C 2 and C3 determine the positive feedback coefficient of LC oscillatory circuit, and the ratio range of positive feedback coefficient can be 1/2～1/8; C1 is a coupling capacitance; Inductance L 1 and capacitor C 4 guarantee that oscillation frequency is 120MHz before annular capacitor Cp inserts the LC oscillatory circuit.The frequency computation part formula of LC oscillatory circuit is as follows:

$f=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}---\left(1\right)$

Wherein, L=L1, when Cp did not have place in circuit, the electric capacity in the LC oscillatory circuit was $C=\frac{1}{\frac{1}{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="H2009202469691E00012.png,H2009202469691E00031.png"\; state="\{\{state\}\}">C</figure-callout>}2}+\frac{1}{\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="H2009202469691E00031.png"\; state="\{\{state\}\}">C</figure-callout>}3}+\frac{1}{\mathrm{<figure-callout\; id="4"\; label="C"\; filenames="H2009202469691E00031.png"\; state="\{\{state\}\}">C</figure-callout>}4}}.$

Because capacitor C 2 is far longer than the appearance value of capacitor C 4, capacitor C 3 is far longer than the appearance value of capacitor C 4, so capacitor C 2, C3 can ignore to the influence of oscillation frequency.After annular capacitor Cp inserted the LC oscillatory circuit, the electric capacity in the LC oscillatory circuit was C=C4+Cp, and by formula (1) as can be known, this moment, the oscillation frequency of LC oscillatory circuit reduced, and was 80MHz～120MHz.Therefore, the centre frequency of described high-frequency signal is about 120MHz, and when capacitor C p appearance value increased, frequency can descend, and frequency range need be carried out processing and amplifying between 80-120MHz.

As shown in Figure 4, the two-stage amplifying circuit that comprises series connection according to the amplifying circuit of the sensor node of node unit of the present utility model, first order amplifying circuit comprises metal oxide semiconductor field effect tube (MOSFET) Q2, preferred model is 2SK241, resistance R 5, R6, R7, diode D1, diode D2 and capacitor C 6.Resistance R 5, R6 and R7 provide quiescent point for amplifying circuit, and diode D1, D2 provide temperature compensation for amplifying circuit, and capacitor C 6 is used for filtering; Second level amplifying circuit comprises triode Q3, and preferred model is 2SC2570, resistance R 8, R9, R10, R11, and capacitor C 7, C8.Resistance R 8, R9, R10, R11 make it be operated in linear amplification region for Q3 provides suitable quiescent point, and capacitor C 7, C8 play the stopping direct current effect.By the two-stage amplifying circuit, will amplify by the high frequency small-signal of above-mentioned high-frequency circuit output, so that in plastic sub-frequency circuit, frequency signal is carried out shaping and frequency division.

As shown in Figure 5, comprise two high speed integrated chips, preferably, be SN74AHCT14 and SN74F161 according to plastic sub-frequency circuit of the present utility model.Chip SN74AHCT14 is used for frequency signal is carried out shaping, makes sinusoidal signal become square-wave signal, so that frequency division; Chip SN74F161 is used for this square-wave signal is carried out frequency division, makes that the signal behind the frequency division can the collection of Be Controlled processing unit.

The concrete course of work of multipoint mode moisture transducer of the present utility model is as follows: because the annular capacitor in the node unit is surrounded by soil, the variation that how much can cause soil dielectric constant of soil moisture content, and then influence the variation of annular capacitor appearance value, the variation of appearance value can cause the variation of oscillation frequency again, therefore, can come the moisture of measured soil by the oscillation frequency in the measurement high-frequency circuit.In order to reduce power consumption, the sensor most of the time is in dormant state, do not carry out the measurement of soil water content, when the external world needs the measured soil moisture, the user sends corresponding instruction according to the requirement of the soil surveying degree of depth, wake controlled processing unit up by communication unit, controlled processing unit receives user's command information, by node selected cell gating and the power supply of specifying the corresponding sensor node medium-high frequency of depth of soil circuit, this sensor node will enter duty, carries out and measures; Owing to there are a plurality of nodes, the user can select one or more measurement points simultaneously, realizes multimetering; Owing to be provided with timing unit, can realize measuring in real time or regularly; The high-frequency signal that measure to obtain is converted to the frequency signal of can the Be Controlled processing unit gathering through amplifying circuit and frequency dividing circuit, processing and demarcation by controlled processing unit, the content of measured soil moisture indirectly, then, controlled processing unit can send the data of measuring to user by communication module.After this, sensor node can reenter dormant state under the control of controlled processing unit.

Above embodiment only is used to illustrate the utility model; and be not to restriction of the present utility model; the those of ordinary skill in relevant technologies field; under the situation that does not break away from spirit and scope of the present utility model; can also make various variations and modification; therefore all technical schemes that are equal to also belong to category of the present utility model, and scope of patent protection of the present utility model should be defined by the claims.

Claims (10)

1. A multi-point soil moisture sensor comprising: Power supply unit, which supplies power to the whole sensor; a communication unit, receiving user instruction information including the soil depth to be measured, sending the information to the control processing unit and receiving moisture measurement data therefrom and feeding the data back to the user; Control the processing unit, send the user instruction information to the node selection unit, collect and process the frequency signal output by the sensor node selected and connected by the node selection unit, obtain moisture measurement data, and output it to the communication unit; a node selection unit, which selects corresponding sensor nodes in the connected node unit according to the user instruction information from the control processing unit; The node unit includes N sensor nodes respectively corresponding to different soil depths, and the nodes selected to be connected by the node selection unit will amplify, shape and frequency-divide the high-frequency signals obtained from the measurement, and output them that can be collected by the control processing unit Frequency signal; wherein, N is not greater than 8. 2. The multi-point soil moisture sensor according to claim 1, further comprising a timing unit, which regularly sends the user instruction information to the communication unit. 3. multi-point soil moisture sensor as claimed in claim 1, is characterized in that, described power supply unit is integrated chip ASM1117; Described communication unit is RS485 module or wireless module; Described control processing unit is single-chip microcomputer chip C8051F930; The node selection unit is a chip CD4051. 4. The multi-point soil moisture sensor according to claim 1, wherein each sensor node comprises: a high-frequency measurement circuit, an amplification circuit and a shaping frequency division circuit. 5. The multi-point soil moisture sensor as claimed in claim 3, characterized in that, the high-frequency measurement circuit is an LC oscillator circuit comprising a ring capacitor. 6. The multi-point soil moisture sensor according to claim 5, characterized in that, the ring capacitance is two stainless steel rings connected by insulating materials. 7. The multi-point soil moisture sensor according to claim 3, wherein the amplifying circuit comprises a two-pole amplifying circuit connected in series. 8. The multi-point soil moisture sensor according to claim 3, characterized in that, the shaping frequency division circuit comprises chips SN74AHCT14 and SN74F161. 9. The multi-point soil moisture sensor according to claim 1, wherein the N sensor nodes are sequentially connected with a predetermined distance through an insulating medium. 10. The multi-point soil moisture sensor according to any one of claims 1-9, characterized in that each sensor node is made into a ring shape.

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