CN111522049A - Alpha surface pollution simulation detection method - Google Patents
Alpha surface pollution simulation detection method Download PDFInfo
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- CN111522049A CN111522049A CN202010290138.5A CN202010290138A CN111522049A CN 111522049 A CN111522049 A CN 111522049A CN 202010290138 A CN202010290138 A CN 202010290138A CN 111522049 A CN111522049 A CN 111522049A
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- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/169—Exploration, location of contaminated surface areas
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- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
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- G01T1/167—Measuring radioactive content of objects, e.g. contamination
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- G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
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Abstract
The invention relates to an α pollution simulation detection method which specifically comprises the following steps of initializing a system, setting the output of a zero setting circuit to be 0 and the amplification factor to be maximum before a sensor unit works, switching a common output end of an analog switch switching unit to an ith sensor under a nonmagnetic condition, and carrying out zero setting on the sensors in a sensor array in the sensor unit, wherein i is more than or equal to 1 and less than or equal to n, n is the number of the sensors in the sensor array, and measuring an analog source, namely collecting the analog source stained on the surface of a person or an object through the sensor array in a preset analog detection area, wherein the measurement result of the ith sensor is Vi＝(VSi‑VRi)/2。
Description
Technical Field
The invention relates to the technical field of radioactive pollution detection, in particular to an alpha pollution simulation detection method.
Background
Alpha surface contamination is one type of radioactive contamination, which refers to contamination of the surface of a person or object with radionuclides that release alpha particles. In nuclear emergency medical rescue, when a pollution accident occurs, people and objects entering and exiting a pollution area need to be detected; the personnel need to be decontaminated when polluted, and the decontamination effect needs to be evaluated by detecting before and after each decontamination.
In the alpha surface pollution simulation, a simulation source which has alpha surface pollution characteristics and has no harm to personnel and environment is developed and applied to the simulation training of alpha surface pollution detection and decontamination. Simulated sources made with magnet blocks, safe liquid sprays and powders have been developed in the prior art. However, these simulation sources need to be used with a specific real alpha surface contamination detection instrument, which greatly limits the application range thereof. In addition, the prior art also proposes that a light-emitting diode is adopted to manufacture an analog source, or a surface pollution simulation garment is manufactured, and a bar code on the simulation garment is used as the analog source; however, the analog source made of the light-emitting diode has large volume and can only be used as an alpha radiation source, and is difficult to be used for surface pollution simulation; the simulation value of the bar code on the simulation clothes is fixed, and the change process of alpha surface pollution decontamination is difficult to simulate; and the two simulation methods have large limitations and cannot effectively simulate alpha surface pollution.
Disclosure of Invention
In view of the problems in the prior art, the present invention is directed to an analog detection method of α contamination, in which each sensor is provided with a respective set/reset circuit to set/reset the sensor when the magnetic field strength exceeds a preset value to restore the sensitivity of the sensor. Meanwhile, an analog switch switching unit is selected, for example, an analog switch switching circuit outputs each sensor in the sensor array one by one, a single chip microcomputer control unit sends out a control signal to control an address line of the analog switch switching unit, and the sensor required to be output is selected. The invention adopts a two-stage amplification and filtering circuit, wherein the amplification factor of the first stage amplification and filtering circuit is fixed, for example, the amplification factor of the first stage amplification and filtering circuit is 5 times, the amplification factor of the second stage amplification and filtering circuit is adjustable, and a singlechip sends a control signal to control an amplification factor control circuit to adjust a resistor RG2 to a preset value, thereby realizing the control of the resistor RG in the second stage amplification and filtering circuit and controlling the amplification factor of the second stage. In the invention, under the condition of no magnetism, when the output of the sensor is not zero, the resistance in the zero setting circuit is controlled by the singlechip control unit, and the automatic zero setting is realized by combining the voltage division circuit and the operational amplifier.
The technical scheme of the invention is as follows:
an alpha pollution simulation detection method specifically comprises the following steps:
an alpha pollution simulation detection method specifically comprises the following steps:
the method comprises the following steps: carrying out system initialization:
before the sensor unit works, the output of the zero setting circuit is set to be 0, and the amplification factor is set to be the maximum value;
step two: zero setting is carried out on the sensor under the nonmagnetic condition:
under the nonmagnetic condition, the public output end of the analog switch switching unit is switched to the ith sensor, and the sensors in the sensor array in the sensor unit are zeroed; wherein i is more than or equal to 1 and less than or equal to n; n is the number of sensors in the sensor array;
step three: simulation source measurement:
collecting simulation sources stained on the surface of a person or an object through a sensor array in a preset simulation detection area; wherein the measurement result of the i-th sensor is Vi＝(VSi-VRi)/2。
Preferably, the specific steps of zeroing the sensor in the absence of magnetism are as follows:
s1: determining that the magnet is in a nonmagnetic condition;
s2: switching a common output terminal of the analog switch switching circuit to an ith sensor; i represents the ith sensor, wherein i is more than or equal to 1 and less than or equal to n;
s3: judging the output result V of the amplifying and filtering circuitoiWhether it is zero:
if the output result V of the filter circuit is amplifiedoiIf not, go to step S4;
if the output result V of the filter circuit is amplifiedoiIf it is zero, go to step S5;
s4: digital potentiometer R of adjusting zero setting circuitAThen, the process returns to step S3 to amplify the output result V of the filter circuitoiJudging, amplifying and filtering circuit VoiWhether the output result of (a) is zero;
s5: storing zeroing value R of ith sensorAi(ii) a Then returning to step S2 to switch sensors and repeat the above steps until all sensors in the sensor array have completed zeroing, i is n;
preferably, the specific steps of simulating source measurement are as follows:
s6: switching a common output end of the analog switch switching circuit to an ith sensor, wherein i is more than or equal to 1 and less than or equal to n; n is the number of sensors in the sensor array of the sensor unit;
s7: adjusting the digital potentiometer of the zero-setting circuit to RAi；
S8, setting the sensor;
s9: judging the output result V of the amplifying and filtering circuitSiWhether or not it satisfies 0.5V < VSi＜1.5V？
If the output result V of the filter circuit is amplifiedSiSatisfy 0.5V < VSiIf the voltage is less than 1.5V, the process is switched to S12;
if the output result V of the filter circuit is largeSiNot satisfying 0.5V < VSiIf the voltage is less than 1.5V, the process is switched to S10;
s10: adjusting the magnification;
s11, judging whether the magnification reaches the maximum value, for example, 3530 times or the minimum value, for example, 7.5 times; if the magnification reaches the maximum or minimum, the process proceeds to step S12; if the magnification does not reach the maximum value or the minimum value, repeating the steps S9 to S11 to adjust the magnification until the magnification reaches the maximum value or the minimum value, and entering S12;
s12: storing the output result V of the amplifying filter circuitSi；
S13: resetting the sensor;
s14: output structure V of storage amplification filter circuitRi(ii) a Switching the common output end of the analog switch switching circuit to the (i + 1) th sensor, and repeating the steps from S6 to S14 until all the sensors finish measurement;
s15: the measurement result of the ith sensor is Vi ═ V (V)Si-VRi)/2。
Preferably, the analog source has the external characteristic of alpha surface contamination, capable of providing a safe signal to be picked up by the sensor unit.
Preferably, each sensor in the sensor array applies a current not less than 500mA to a set/reset resistor of each sensor through a respective set/reset circuit, and generates a strong magnetic field to enable the magnetic sensitive area of the sensor to be uniformly aligned to the first direction to realize setting; when reverse current is applied, the magnetic sensitive area resets in the direction opposite to the first direction, the sensitivity of the sensor is recovered, and the interference of an external strong magnetic field is eliminated.
Preferably, the single chip microcomputer control unit sends out a control signal to control an address line of the analog switch switching unit so as to control the analog switch switching unit to communicate the ith sensor with the common output end for output.
Preferably, the amplification factor of the first-stage amplification filtering unit is 5.
Preferably, the singlechip control unit sends a control signal to the potentiometer, and automatic zero setting is realized through the voltage division circuit and the operational amplifier.
Preferably, the amplification factor of the second-stage amplification filter circuit is controlled by the amplification factor control unit and the digital potentiometer of the zero setting unit, and is adjustable within the range of 1.5-706.
Preferably, each sensor is connected with a respective setting and resetting circuit, and a control signal access end of the setting/resetting circuit receives a clock pulse signal from the singlechip control unit, so that the corresponding sensor is set or reset and then acquired.
Preferably, each sensor is connected with the analog switch switching unit respectively, data transmission is performed through a common output end of the analog switch switching unit, and the analog switch switching circuit outputs output signals of each sensor one by one;
preferably, the output of the analog switch switching unit is transmitted to an amplifying and filtering unit; the amplifying and filtering unit comprises a first-stage amplifying and filtering unit and a second-stage amplifying and filtering unit, the amplification factor of the first-stage amplifying and filtering unit is fixed so as to suppress original noise, and the reference end of the first-stage amplifying and filtering unit is connected with the output end of the zeroing circuit; the gain of the second-stage amplification filtering unit is independently adjustable, and the amplification factor can be adjusted through the amplification factor adjusting circuit;
if the output of the ith sensor is zero under the condition of no magnetism, the singlechip control unit does not send a control signal to carry out zero setting control, and the voltage value of the reference end of the first-stage amplification filtering unit is 0V; if the output of the ith sensor is not zero under the nonmagnetic condition, the singlechip control unit sends a control signal to carry out zero setting control, and the voltage value of the reference end of the first-stage amplification filtering unit is the voltage value actually output by the sensor under the nonmagnetic condition; an RC oscillating circuit is arranged at the output of the first-stage amplifying and filtering unit and the input end of the second-stage amplifying and filtering circuit, and the negative input end of the second-stage amplifying and filtering unit is grounded; the singlechip sends a control signal to the amplification factor control circuit to control the output value of the RG resistor of the amplification factor; the amplified and filtered signals are processed by an A/D acquisition unit in the singlechip control unit, converted into digital signals capable of being processed by the singlechip, and displayed and alarmed.
Compared with the prior art, the invention has the advantages that:
the alpha pollution simulation detection method of the invention is characterized in that each sensor is provided with a respective set reset circuit, so that when the intensity of magnetic field exceeds a preset value, the sensor is set/reset to recover the sensitivity of the sensor. Meanwhile, an analog switch switching unit is selected, for example, an analog switch switching circuit outputs each sensor in the sensor array one by one, a single chip microcomputer control unit sends out a control signal to control an address line of the analog switch switching unit, and the sensor required to be output is selected. The invention adopts a two-stage amplification and filtering circuit, wherein the amplification factor of the first stage amplification and filtering circuit is fixed, for example, the amplification factor of the first stage amplification and filtering circuit is 5 times, the amplification factor of the second stage amplification and filtering circuit is adjustable, and a singlechip sends a control signal to control an amplification factor control circuit to adjust a resistor RG2 to a preset value, thereby realizing the control of the resistor RG in the second stage amplification and filtering circuit and controlling the amplification factor of the second stage. In the invention, under the condition of no magnetism, when the output of the sensor is not zero, the resistance in the zero setting circuit is controlled by the singlechip control unit, and the automatic zero setting is realized by combining the voltage division circuit and the operational amplifier.
Drawings
The advantages of the above and/or additional aspects of the present invention will become apparent and readily appreciated from the following description of the embodiments taken in conjunction with the accompanying drawings of which:
fig. 1 is a flowchart of an α contamination mode detection method according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of an analog detection device of an α contamination analog detection method according to an embodiment of the present invention.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
Fig. 1 shows an alpha contamination simulation detection method according to an embodiment of the present invention, which specifically includes the following steps:
the method comprises the following steps: carrying out system initialization:
s1: before the sensor unit works, the output of the zero setting circuit is set to be 0, and the amplification factor is set to be the maximum value;
preferably, the maximum value of the magnification is 3530.
Preferably, the analog source has the external characteristic of alpha surface contamination, capable of providing a safe signal to be picked up by the sensor unit.
Preferably, the preparation method of the analog source is as follows;
uniformly mixing 6g of Ru FeB magnetic powder with 20ml of 0.5% agarose gel; magnetizing the mixture under a uniform magnetic field of 330mT to prepare magnetic powder colloid; applying the prepared magnetic powder colloid to the surface of a nonmagnetic object, such as clothes and/or body surface; and (4) correcting the magnetic field at the position of the magnet block with the surface of 120mT and 1cm away from the magnetic powder colloid to obtain the prepared simulation source.
Step two: the method comprises the following steps of switching sensors of a sensor array one by one under a nonmagnetic condition, and zeroing the sensors, wherein the method specifically comprises the following steps:
s1: determining that the magnet is in a nonmagnetic condition;
s2: switching a common output terminal of the analog switch switching circuit to an ith sensor; i represents the ith sensor, wherein i is more than or equal to 1 and less than or equal to n;
s3: judging the output result V of the amplifying and filtering circuitoiWhether it is zero:
if the output result V of the filter circuit is amplifiedoiIf not, go to step S4;
if the output result V of the filter circuit is amplifiedoiIf it is zero, go to step S5;
s4: digital potentiometer R of adjusting zero setting circuitAThen, the process returns to step S3 to amplify the output result V of the filter circuitoiJudging, amplifying and filtering circuit VoiWhether the output result of (a) is zero;
s5: storing zeroing value R of ith sensorAi(ii) a Then returning to step S2 to switch sensors and repeat the above steps until all sensors in the sensor array have completed zeroing, i is n;
step three: collecting simulation sources stained on the surface of a person or an object through a sensor array in a preset simulation detection area; the method specifically comprises the following steps:
s6: switching a common output end of the analog switch switching circuit to an ith sensor, wherein i is more than or equal to 1 and less than or equal to n; n is the number of sensors in the sensor array of the sensor unit;
s7: adjusting the digital potentiometer of the zero-setting circuit to RAi；
S8, setting the sensor;
s9: judging the output result V of the amplifying and filtering circuitSiWhether or not it satisfies 0.5V < VSi＜1.5V？
If the output result V of the filter circuit is amplifiedSiSatisfy 0.5V < VSiIf the voltage is less than 1.5V, the process is switched to S12;
if the output result V of the filter circuit is largeSiNot satisfying 0.5V < VSiIf the voltage is less than 1.5V, the process is switched to S10;
s10: adjusting the magnification;
s11, judging whether the magnification reaches the maximum value 3530 times or the minimum value 7.5 times; if the magnification reaches the maximum or minimum, the process proceeds to step S12; if the magnification does not reach the maximum value or the minimum value, repeating the steps S9 to S11 to adjust the magnification until the magnification reaches the maximum value or the minimum value, and entering S12;
s12: storing the output result V of the amplifying filter circuitSi；
S13: resetting the sensor;
s14: output structure V of storage amplification filter circuitRi(ii) a Switching the common output end of the analog switch switching circuit to the (i + 1) th sensor, and repeating the steps from S6 to S14 until all the sensors finish measurement;
s15: the measurement result of the ith sensor is Vi ═ V (V)Si-VRi)/2。
Preferably, the amplifying and filtering circuit comprises two stages of amplifying and filtering circuits, the amplification factor of the first stage of amplifying and filtering circuit is fixed, and the amplification factor of the second stage of amplifying and filtering circuit is adjustable.
When the magnetic field intensity is larger than a first preset value, a control signal access end of the setting/resetting circuit receives a clock pulse signal from the singlechip control unit to realize setting or resetting of the corresponding sensor;
preferably, as shown in fig. 2, each sensor in the sensor array applies a current of not less than 500mA to a set/reset resistor of each sensor through a respective set/reset circuit, and generates a strong magnetic field to make the magnetic sensitive area of the sensor align to the first direction uniformly to realize setting; when reverse current is applied, the magnetic sensitive area resets in the direction opposite to the first direction, the sensitivity of the sensor is recovered, and the interference of an external strong magnetic field is eliminated;
the sensors are respectively connected with the analog switch switching unit, data transmission is carried out through the common output end of the analog switch switching unit, and the analog switch switching circuit outputs the output signals of the sensors one by one;
preferably, the single chip microcomputer control unit sends out a control signal to control an address line of the analog switch switching unit, for example, a three-bit binary address line to control the analog switch switching unit to connect the ith sensor to the common output terminal for output.
Preferably, the analog switch switching unit switches one of the n differential inputs to the common output, in particular as determined by 3-bit binary address lines (a0, a1, a2), wherein the minimum value of the input high level is 2.0V and the maximum value of the input low level is 0.8V. When the power is supplied at +/-5V, the dynamic switching time is 600ns, the on-resistance is 21 omega, wherein n is more than or equal to 2.
The output of the analog switch switching unit is transmitted to the amplifying and filtering unit, the amplifying and filtering unit comprises a first-stage amplifying and filtering unit and a second-stage amplifying and filtering unit, and the amplification times of the first-stage amplifying and filtering unit are fixed.
Preferably, the amplification factor of the first-stage amplification filtering unit is 5.
If the output of the ith sensor is not zero under the nonmagnetic condition, setting the voltage value of the reference end of the first-stage amplification filtering unit as the output voltage of the sensor under the nonmagnetic condition through a zero setting circuit; the singlechip control unit sends a control signal to the potentiometer, and automatic zero setting is realized through the voltage division circuit and the operational amplifier.
The singlechip sends a control signal to the amplification factor control circuit to control the output value of the RG resistor of the amplification factor.
Preferably, the amplification factor of the second-stage amplification filtering unit is adjustable, and specifically, the amplification factor of the second-stage amplification filtering circuit is adjustable within a range of 1.5 to 706 under the control of the amplification factor control unit and the digital potentiometer of the zero setting unit. The gain of the second stage amplifying and filtering circuit is independently adjustable, the gain of the second stage amplifying and filtering circuit is controlled by a resistor RG, and the amplification factor is preferably the amplification factor
The amplified and filtered signals are processed by an A/D acquisition unit in the singlechip control unit and converted into digital signals which can be processed by the singlechip. And then displaying and alarming.
Preferably, in nuclear emergency medical rescue, when a pollution accident occurs, people and objects entering and exiting a polluted area need to be detected; the personnel need to be decontaminated when polluted, and the decontamination effect needs to be evaluated by detecting before and after each decontamination.
Fig. 2 shows an analog detection device for alpha surface contamination detection according to an embodiment of the present invention, which includes a sensor unit, an analog signal processing unit, a single chip microcomputer control unit, a display unit, and an alarm unit. The sensor unit is connected with the analog signal processing unit and comprises a sensor array, each sensor in the sensor array is connected with a setting/resetting circuit, the setting/resetting circuit is connected with the singlechip control unit, a control signal access end of the setting/resetting circuit receives a clock pulse signal from the singlechip, a square wave of the clock pulse is amplified, a current not less than 500mA is applied to the setting/resetting electricity of the sensor, and a strong magnetic field is generated to enable the magnetic sensitive area of the sensor to be uniformly aligned to the first direction to realize setting; when reverse current is applied, the magnetic sensitive area resets in the direction opposite to the first direction, the sensitivity of the sensor is recovered, and the interference of an external strong magnetic field is eliminated. The analog signal processing unit comprises an analog switch switching unit, an amplification filtering unit and an offset compensation circuit. The output end of the amplifying and filtering unit is connected to an analog-to-digital conversion module of the singlechip control unit, namely an A/D acquisition unit. The single chip microcomputer is connected to the display unit and the alarm unit.
The sensor unit comprises a sensor array, each sensor in the sensor array is connected with a respective set/reset circuit, and when the magnetic field intensity of an interference magnetic field exceeds 20 Gs. When the sensor is in use, a strong recovery magnetic field in a transient state is applied to a sensitive element of the sensor, such as a magnetic sensitive area, through a set-reset circuit to recover or maintain the characteristic of the sensitive element; the output end S/R + of each set/reset circuit is connected to the S/R + end of the corresponding sensor. The S/R-of the sensor is grounded.
The set/reset circuit is controlled by a singlechip control unit.
Specifically, the single chip microcomputer control unit sends out clock pulses, such as square waves, and controls the setting/resetting circuit to carry out corresponding setting and resetting.
Preferably, the sensor comprises a set/reset resistor.
Specifically, the set/reset circuit comprises a first chip, a first capacitor, a second capacitor and a resistor, the cut-off circulation unit is connected with the single chip, and each drain of the cut-off circulation unit is connected to a first end of the second capacitor C9; the first end of the first chip is grounded, the second end and the fourth end of the first chip are connected with the single chip to receive clock pulses of the single chip, the third end of the first chip is connected with the RC series oscillation circuit, the fifth end, the sixth end, the seventh end and the eighth end of the first chip are respectively connected to the first end of the second capacitor, the second end of the second capacitor is provided with an S/R + wiring end to be connected with the sensors, and particularly, the S/R + wiring end of the set/reset circuit is connected to the S/R + wiring end of each sensor. The S/R-of each sensor is grounded.
The power supply of the RC oscillating circuit is 5V, the second end of the first capacitor is grounded, and the first end of the first resistor R1 is connected with + 5V.
The singlechip is connected to the input end of the setting/resetting circuit.
Preferably, the capacitance value of the second capacitor is 0.1 times that of the first capacitor, and the clock pulse signal sent by the mcu, for example, when the control signal is from low level, for example, 0V, to high level, for example, 3.3V, the transient voltage across the second capacitor is raised to 5V by the RC oscillation circuit, so as to apply a transient current of not less than 500mA to the set/reset resistor of the sensor, thereby setting the sensor.
When a clock pulse signal sent by the singlechip is from a high level to a low level, a reverse current is applied to a set/reset resistor of the sensor, and a magnetic sensitive area faces to the opposite direction, so that the reset is realized, the sensitivity of the sensor is recovered, and the interference of an external strong magnetic field is eliminated.
Preferably, the set/reset resistance of the sensor is an internal resistance between the S/R + terminal of the sensor and the S/R-terminal of the sensor, and further preferably, the resistance between the S/R + terminal of the sensor and the S/R-terminal of the sensor is 5 Ω, so as to realize that a transient current of not less than 500mA is applied to the set/reset resistance of the sensor to realize the setting of the sensor, wherein the S/R-terminal of the sensor is grounded.
Preferably, the sensor is a magnetoresistive sensor that converts a sensitive directional magnetic field strength into a differential output voltage.
Preferably, the sensor has a measurement range of + -6 Gauss, a resolution of 85 μ Gs, a working voltage of 5V, and a sensitivity of (1.0 + -0.2) mV/V/Gs.
The set/reset circuit applies a current of not less than 500mA to a set/reset resistor of the sensor, namely a resistor between an S/R + terminal of the sensor and an S/R-terminal of the sensor, generates a strong magnetic field to enable magnetic regions of the sensor to be uniformly aligned to one direction (set), and when a reverse current is applied, the magnetic regions face to the opposite direction (reset), the sensitivity of the sensor is recovered, and the interference of an external strong magnetic field is eliminated.
The setting/resetting circuit is controlled by a singlechip; the singlechip sends out a clock signal. The first chip in the set-reset circuit is an integrated chip of an N-channel MOS tube and a P-channel MOS tube, and set/reset pulses are generated under the control of two external capacitors and a clock signal. The analog signal processing unit comprises an analog switch switching circuit and a programmable amplifying and filtering circuit. The singlechip control unit comprises an A/D converter. And the singlechip control unit sends out a set/reset pulse and sends the set/reset pulse to the grids of the N-channel unit and the P-channel unit of the first chip.
Specifically, the sensor includes eight terminals, from top to bottom are sensor first terminal, sensor second terminal, sensor third terminal and sensor fourth terminal, sensor fifth terminal, sensor sixth terminal, sensor seventh terminal and sensor eighth terminal in proper order, wherein, the first terminal of sensor is the OUT-terminal of sensor, and it is connected to the simulation switches on the unit, specifically, is connected to the channel-terminal of simulation switch switching circuit. The second terminal of the sensor is V of the sensorbridgeAnd the terminal is connected with a +5V power supply. And the third terminal of the sensor is an S/R + terminal of the sensor and is connected with an output electrode S/R + of the set reset circuit. And the fourth terminal of the sensor is grounded. The resistance value of the resistor between the S/R + of the sensor and the S/R-of the sensor is 5 omega.
And the fifth terminal of the sensor and the sixth terminal of the sensor are empty. And the eighth terminal of the sensor is an OUT + terminal of the sensor, and the eighth terminal of the sensor is connected to a channel + terminal of the analog switch switching circuit.
Each sensor is respectively connected with the analog switch switching unit, each sensor carries out data transmission through the common output end of the analog switch switching unit, and the analog switch switching circuit selects one pair of channel signals of two paths of output signals of each sensor, for example, 10 paths of output signals of 5 sensors, to carry out differential amplification, that is, the output signals of each sensor are output one by one.
Specifically, the positive output terminal OUT + of the ith sensor is connected to the positive input terminal channel of the analog switch switching unit, and the negative output terminal OUT-of the ith sensor is connected to the negative input terminal channel-of the analog switch switching unit, where i is 2,3, 4. Single chip microcomputer control unit
The common output end of the analog switch switching unit is respectively a positive output end channel + of the analog switch switching unit and a negative output end channel-of the analog switch switching unit. The singlechip control unit sends out a control signal to control an address line of the analog switch switching unit, for example, a three-bit binary address line to control the analog switch switching unit to communicate the ith sensor with the common output end for output.
The analog switch switching unit switches one of the n differential inputs to a common output, which is determined by 3-bit binary address lines (A0, A1, A2), wherein the minimum value of the input high level is 2.0V, and the maximum value of the input low level is 0.8V. When the power is supplied at +/-5V, the dynamic switching time is 600ns, the on-resistance is 21 omega, wherein n is more than or equal to 2.
The output voltage signal of the sensor is +/-425 mu V to +/-30 mV, is very weak, cannot be directly processed, and needs to be amplified and filtered. Meanwhile, in order to fully utilize the A/D range, the requirement on the gain of the amplifying and filtering circuit of the whole amplifying and filtering unit is higher, and because the gain of the first-stage amplification is not suitable to be too large, the circuit of the amplifying and filtering unit adopts two-pole amplification, and an RC filtering circuit is added while the signal-to-noise ratio is improved, so that interference signals are well reduced. The filter amplifying circuit is the key for the operation of the whole system, and the amplifying filter circuit has high input impedance, low offset voltage and high common mode rejection ratio.
The analog switch switching circuit is connected with an amplifying and filtering circuit, and preferably, the amplifying and filtering circuit is a programmable amplifying and filtering circuit. Preferably, the amplifying and filtering circuit in the invention is a two-stage amplifying circuit, which simultaneously reduces the number of components. The amplifying and filtering circuit comprises a first-stage amplifying and filtering circuit and a second-stage amplifying and filtering circuit. The positive input end channel + of the first-stage amplification circuit is connected to the positive public output end channel + of the public output end of the analog switch switching circuit, and the negative input end channel-of the second-stage amplification filter circuit is connected to the negative public output end channel-of the public output end of the analog switch switching circuit.
The amplified and filtered signals are processed by an A/D acquisition unit in the singlechip control unit and converted into digital signals which can be processed by the singlechip.
The amplification factor of the first stage amplification filter circuit is fixed, for example, the amplification factor of the first stage amplification filter circuit is 5.
Specifically, the amplification factor of the second-stage amplification filter circuit is controlled by the amplification factor control unit and the digital potentiometer of the zero setting unit, and is adjustable within the range of 1.5-706. The gain of the second stage amplifying and filtering circuit is independently adjustable, the gain of the second stage amplifying and filtering circuit is controlled by a resistor RG, and the amplification factor is preferably the amplification factor
The second resistor R10, the third resistor R13, the third capacitor C27, the fourth capacitor C29, and the fifth capacitor C32 form a radio frequency filter circuit, wherein a first end of the second resistor R10 is connected to a positive input end of the first-stage amplification filter circuit. A first end of the third resistor R13 is connected to the negative input terminal of the first stage of the amplifying and filtering circuit. A first terminal of the third capacitor C27 is grounded, a second terminal of the third capacitor C27 is connected to a first terminal of the fourth capacitor C29, a second terminal of the fourth capacitor C29 is connected to a first terminal of the fifth capacitor C32, and a second terminal of the fifth capacitor C32 is grounded. The second terminal of the second resistor R10 is connected to the second terminal of the third capacitor C27 or to the first terminal of the fourth capacitor C29. The second terminal of the third resistor R13 is connected to the second terminal of the fourth capacitor C29 or to the first terminal of the fifth capacitor C32. The negative output end of the radio frequency filter circuit is connected with the negative input end of the first-stage amplifier, and the positive input end of the radio frequency filter circuit is connected with the negative input end of the first-stage amplifier. And the negative input end of the radio frequency filter circuit is connected to the second end of the second resistor, the second end of the third capacitor and the first end of the fourth capacitor. And the positive input end of the radio frequency filter circuit is connected to the second end of the third resistor, the second end of the fourth capacitor and the first end of the fifth capacitor.
And a fourth resistor of the first-stage amplifier of the radio frequency filter circuit is a fixed resistor R12.
Preferably, the second resistor and the third resistor have the same resistance value.
Preferably, the capacitance values of the third capacitor and the fifth capacitor are equal, and the capacitance value of the fourth capacitor is 10 times that of the first capacitor or the fifth capacitor.
Preferably, the resistance of R12 is 12.4K Ω.
Preferably, the resistance of R10 is 4.02 k.OMEGA.and the resistance of R13 is 4.02 k.OMEGA..
Preferably, the capacitance value of C27 is 1nF, the capacitance value of C32 is 1nF, and the capacitance value of C29 is 10 nF.
Due to the fact that offset voltage exists in a bridge bias and amplifying and filtering unit of the sensor, when no magnetic field exists, the output of the ith sensor is a first preset value Vi, the first preset value Vi is not zero, the reference end of the first-stage amplifying and filtering circuit is connected with the output end of the zeroing unit, and the reference voltage of the reference end of the first-stage amplifying circuit is set to be the output voltage difference Vi of the ith sensor. The zero setting unit comprises a zero setting circuit, an adjustable resistor is arranged in the adjustment circuit, the adjustable resistor sends a control signal through a single chip microcomputer to modulate the resistance value of the adjustable resistor, a first zero setting resistor and a second zero setting resistor jointly form a voltage division circuit to realize automatic zero setting, the output voltage of the zero setting circuit is equal to the output voltage value of an ith sensor, namely the input of the first-stage amplification filter circuit is zero, and the output of the first-stage amplification filter circuit is also zero.
Preferably, the voltage of the voltage division circuit is +5V to-5V. And connecting the output end of the first-stage amplification filter circuit to the input end of the second-stage amplification filter circuit. And the reference end of the second-stage amplifying and filtering circuit is grounded.
Preferably, the output end of the first-stage amplification filter circuit is connected to the positive input end of the second-stage amplification filter circuit through an RC oscillation circuit composed of a resistor R14 and a capacitor C31, the negative input end of the second-stage amplification filter circuit is grounded, and the resistor RG of the second-stage amplification filter circuit is obtained by controlling the amplification factor control circuit through a single-chip microcomputer control unit.
The first end of the R14 is connected to the positive input end of the second-stage amplification filter, and the second end of the R14 is connected to the output end of the first-stage amplification filter circuit.
The first end of the C31 is connected to the first end of the R14, and the second end of the C31 is grounded.
Preferably, the resistance value of R14 is 10K.
Preferably, the capacitance value of the C31 is 1 μ F.
Preferably, the potentiometer is a digital potentiometer.
Specifically, the amplification factor control unit receives a control signal from the singlechip control unit, determines the value of the RG resistance, outputs the value to a second-stage amplifier of the second-stage amplification filter circuit, and determines that the reference end of the second-stage amplification filter circuit is grounded.
Furthermore, the singlechip is connected to each function key, the digital potentiometer and the analog switch switching circuit.
The digital potentiometer is connected with the singlechip control unit and is used for receiving a clock signal and a control signal from the singlechip control unit and controlling the resistance value of an internal resistor between W1 and L1 of the potentiometer through the singlechip.
In the normal state, R14 and C31 form a low-pass filter with the cut-off frequency of 16 Hz.
The output end of the zero setting circuit is connected with the reference end of the first-stage amplification filter circuit, and the automatic zero setting of the voltage division circuit is formed through a potentiometer, such as a digital potentiometer.
The singlechip control circuit performs A/D conversion on the output signal of the analog signal processing circuit, displays the measurement result through an LCD, and realizes the functions of key control, alarm and the like according to the simulated alpha surface pollution detection equipment.
The singlechip control unit outputs a set/reset circuit clock signal; controlling the amplification factor of the programmable amplifying and filtering circuit; controlling a zero setting circuit; converting the analog signal into a digital signal; processing the digital signal; and controlling display and alarming.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. Those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; the communication may be direct, indirect via an intermediate medium, or internal to both elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. In addition, in the description of the present invention, "at least three" means two or more unless otherwise specified.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. The alpha pollution simulation detection method is characterized by comprising the following steps:
the method comprises the following steps: carrying out system initialization:
before the sensor unit works, the output of the zero setting circuit is set to be 0, and the amplification factor is set to be the maximum value;
step two: zero setting is carried out on the sensor under the nonmagnetic condition:
under the nonmagnetic condition, the public output end of the analog switch switching unit is switched to the ith sensor, and the sensors in the sensor array in the sensor unit are zeroed; wherein i is more than or equal to 1 and less than or equal to n; n is the number of sensors in the sensor array;
step three: simulation source measurement:
collecting simulation sources stained on the surface of a person or an object through a sensor array in a preset simulation detection area; wherein the measurement result of the i-th sensor is Vi＝(VSi-VRi)/2。
2. The alpha contamination simulation detection method of claim 1, wherein the specific steps of zeroing the sensor in a non-magnetic condition are as follows:
s1: determining that the magnet is in a nonmagnetic condition;
s2: switching a common output terminal of the analog switch switching circuit to an ith sensor; i represents the ith sensor, wherein i is more than or equal to 1 and less than or equal to n;
s3: judging the output result V of the amplifying and filtering circuitoiWhether it is zero:
if the output result V of the filter circuit is amplifiedoiIf not, go to step S4;
if the output result V of the filter circuit is amplifiedoiIf it is zero, go to step S5;
s4: digital potentiometer R of adjusting zero setting circuitAThen, the process returns to step S3 to amplify the output result V of the filter circuitoiJudging, amplifying and filtering circuit VoiWhether the output result of (a) is zero;
s5: storing zeroing value R of ith sensorAi(ii) a The process then returns to step S2 to switch sensors and repeat the above steps until all sensors in the sensor array have completed zeroing.
3. The alpha surface simulation detection method according to claim 2, wherein the simulation source measurement comprises the following specific steps:
s6: switching a common output end of the analog switch switching circuit to an ith sensor, wherein i is more than or equal to 1 and less than or equal to n; n is the number of sensors in the sensor array of the sensor unit;
s7: adjusting the digital potentiometer of the zero-setting circuit to RAi；
S8, setting the sensor;
s9: judging the output result V of the amplifying and filtering circuitSiWhether or not it satisfies 0.5V < VSi＜1.5V？
If the output result V of the filter circuit is amplifiedSiSatisfy 0.5V < VSiIf the voltage is less than 1.5V, the process is switched to S12;
if the output result V of the filter circuit is largeSiNot satisfying 0.5V < VSiIf the voltage is less than 1.5V, the process is switched to S10;
s10: adjusting the magnification;
s11, judging whether the magnification reaches the maximum value or the minimum value; if the magnification reaches the maximum or minimum, the process proceeds to step S12; if the magnification does not reach the maximum value or the minimum value, repeating the steps S9 to S11 to adjust the magnification until the magnification reaches the maximum value or the minimum value, and entering S12;
s12: storing the output result V of the amplifying filter circuitSi；
S13: resetting the sensor;
s14: output structure V of storage amplification filter circuitRi(ii) a Switching the common output end of the analog switch switching circuit to the (i + 1) th sensor, and repeating the steps from S6 to S14 until all the sensors finish measurement;
s15: the measurement result of the ith sensor is Vi ═ V (V)Si-VRi)/2。
4. The analog alpha contamination detection method of claim 3, wherein the analog source has an external characteristic of alpha surface contamination capable of providing a safe signal to be collected by the sensor unit.
5. The alpha contamination analog detection method according to claim 4, wherein each sensor in the sensor array applies a current of not less than 500mA to a set/reset resistor of each sensor through a respective set/reset circuit, and generates a strong magnetic field to enable the magnetic sensitive area of the sensor to be uniformly aligned to the first direction for setting; when reverse current is applied, the magnetic sensitive area resets in the direction opposite to the first direction, the sensitivity of the sensor is recovered, and the interference of an external strong magnetic field is eliminated.
6. The alpha pollution simulation detection method of claim 5, wherein the single chip microcomputer control unit sends out a control signal to control the address line of the analog switch switching unit so as to control the analog switch switching unit to connect the ith sensor to the common output terminal for output.
7. The analog alpha contamination detection method of claim 6, wherein the amplification factor of the first stage amplification filter unit is 5.
8. The analog alpha contamination detecting method of claim 7, wherein the single chip microcomputer control unit sends out control signals to the potentiometer, and automatic zero setting is realized through the voltage dividing circuit and the operational amplifier.
9. The analog alpha contamination detection method of claim 8, wherein the amplification factor of the second stage of the amplification filter circuit is adjustable within a range of 1.5 to 706 under the control of the digital potentiometers of the amplification factor control unit and the zeroing unit.
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