Low-power-consumption geomagnetic daily variation magnetometer

Abstract

According to the low-power-consumption geomagnetic daily variation magnetometer, a main data storage communication module communicates with an upper computer through a communication protocol and stores a magnetic field value acquired by a magnetic data acquisition module; the data storage communication module is also connected with a power management module through a line, and the power management module is used for converting a battery power supply into power supplies with different voltages and providing adaptive power supplies for other modules; and the on-off of each module can be controlled by controlling the power switches of different modules. And the magnetic measurement probe module obtains a Larmor signal by utilizing a Larmor effect and coil induction. And the magnetic data acquisition module acquires a corresponding magnetic field value by measuring the frequency of the Larmor signal. The power management module adjusts the working mode of the magnetometer according to the current state of the magnetometer and an external command, so that the overall energy consumption is reduced, the overall power cost is reduced, the defense organization and recovery cost is reduced, and the operation efficiency is improved. And the integrity and the stability of the data are also improved through long-time geomagnetic monitoring and magnetic data recording.

Description

Technical Field

[0001] The invention belongs to the technical field of geomagnetic detection, and in particular relates to a low-power geomagnetic diurnal magnetometer. Background Art

[0002] Geomagnetic monitoring is of great significance in many fields such as natural disaster prevention, scientific research, resource exploration, navigation and positioning. Its data and results provide information for understanding and utilizing earth resources.

[0003] The Larmor effect (Larmor Precession) describes that in an external magnetic field, particles with magnetic moments (such as electrons, protons or atomic nuclei) will rotate around the direction of the magnetic field at a certain frequency. A proton magnetometer, also known as a proton precession magnetometer, determines the strength of the magnetic field by measuring the Larmor precession frequency of hydrogen nuclei (protons) in an external magnetic field.

[0004] At present, proton magnetometers are commonly used in seabed daily change stations at home and abroad. Since the instrument needs to be placed on the seabed, there is a deployment device. Usually, a float is connected above the instrument, and a releaser and a load-bearing block are connected below. The entire system is dropped to the seabed. When recovering, the releaser is used to discard the load-bearing block, and the buoyancy of the float is used to float the magnetometer to the sea surface for recovery. The magnetometer used in the geomagnetic daily change station has a built-in rechargeable battery, and the device battery can sustain work for two to three months. The volume of the proton magnetometer is limited, so there are problems such as limited battery capacity.

[0005] The duration of a single use of the instrument can be determined by two factors: the battery capacity and the power consumption of the instrument. The method of increasing the battery capacity generally uses an external battery tank, but this will sacrifice the volume of the diurnal variation station. Therefore, the present invention designs a low-power geomagnetic diurnal variation magnetometer, which can extend the use time of the geomagnetic monitor while improving the effectiveness of the monitoring data. Summary of the invention

[0006] In order to solve the problems existing in the background technology, the present invention provides a low-power geomagnetic diurnal magnetometer. The instrument retains the original magnetic measurement function and also integrates a power management function, which can be used to increase the use time of the device and is beneficial to the integrity of the data.

[0007] The present invention includes a main body, in which a data storage communication module, a power management module, a magnetic data acquisition module and a magnetic probe module are arranged. The data storage communication module is connected to a host computer through a short-circuit cap and a watertight connector on the end cover of the main body, communicates with the host computer through a communication protocol, and stores the magnetic field value obtained by the magnetic data acquisition module; the data storage communication module is also connected to the power management module through a line, and the power management module is used to convert the battery power into a power supply of different voltages to provide an adaptive power supply for the remaining modules; the power management module can also control the switch of each module by controlling the power switch of different modules. The magnetic probe module obtains the Larmor signal by utilizing the Larmor effect and coil induction. The magnetic data acquisition module obtains the corresponding magnetic field value by measuring the frequency of the obtained Larmor signal.

[0008] The data storage communication module includes a 232 communication circuit, a TF card circuit, a short-circuit cap detection circuit and a button battery. The magnetic field value obtained by the magnetic data acquisition module is stored in the TF card and output to the host computer through the 232 communication circuit. At the same time, the host computer inputs instructions to configure system parameters through the 232 communication circuit. A MOS tube is set in the short-circuit cap detection circuit. The MOS tube detects the state of the short-circuit cap on the end face to control the input disconnection of the battery. The button battery is used to maintain the off-chip RTC clock and the STM32L051C8T6 chip in low-power mode.

[0009] The power management module includes an STM32L051C8T6 chip, an off-chip RTC clock circuit, a power conversion circuit, and a battery. The L051 chip controls the power switches of different modules, thereby controlling the working order of each module and ensuring that each module works reasonably in different working modes; the power conversion circuit and the battery convert power supplies of different voltages to provide adaptive power supplies for the remaining modules; the front-end input end of each voltage-generating circuit is connected to the I / O port of the L051 chip through a MOS tube, and the L051 chip controls whether the target voltage is generated through the MOS tube, and controls the power on and off; the L051 chip chooses to turn on part of the power or turn off the power according to the current state, thereby turning off or on the magnetic data acquisition module and reducing power loss. The battery is charged through an external power adapter connected to the watertight connector on the end cover of the main body.

[0010] The magnetic data acquisition module includes an STM32F407ZGT6 main control chip, an AC polarization circuit, a DC meter polarization circuit, a tuning circuit and a signal detection circuit.

[0011] The AC polarization circuit outputs an AC high-frequency signal, and the output end of the AC polarization circuit is connected to the signal input end of the magnetic probe module; the input end of the AC polarization circuit is connected to the I\O port of the STM32F407ZGT6 main control chip through a MOS tube, and the STM32F407ZGT6 main control chip controls whether the AC polarization circuit works and the working timing through the MOS tube.

[0012] The DC meter polarization circuit outputs a DC voltage signal to provide a DC pulse signal for the magnetic probe module; the input end of the DC meter polarization circuit is connected to the I\O port of the STM32F407ZGT6 main control chip through a MOS tube, and the STM32F407ZGT6 main control chip controls the operation and working timing of the DC meter polarization circuit through the MOS tube.

[0013] The tuning circuit includes multiple capacitor arrays, each of which is connected to the I\O port of the STM32F407ZGT6 main control chip through a MOS tube. The STM32F407ZGT6 main control chip controls the switch of each capacitor array through a MOS tube. The tuning circuit filters and narrowband amplifies the received Larmor signal by selecting a suitable capacitor array.

[0014] The signal detection circuit performs program-controlled amplification and filtering on the signal processed by the matching circuit. The amplified signal is then divided into two paths. One path is the AD voltage acquisition value to obtain the signal strength, and the other path is input to the advanced timer pin of the STM32F407ZGT6 main control chip through a square wave conversion circuit to obtain the signal frequency.

[0015] The magnetic probe module includes a sample chamber, a high-frequency excitation coil, a receiving coil, a shielding layer and a shell. The sample chamber is a glass container containing a free radical solution, and a high-frequency excitation coil is wound outside the sample chamber. The sample chamber is arranged in a frame wound with a DC excitation and signal receiving coil, and the frame is made of insulating material; a shielding layer made of metal material is arranged on the outside of the DC excitation and signal receiving coil to shield the influence of external electromagnetic interference on the resonant cavity and the receiving coil. The end cover of the shell is provided with a first SMA port and a second SMA port, the first SMA port is connected to the high-frequency excitation coil, and is used to input the high-frequency excitation signal generated by the AC polarization circuit of the magnetic data acquisition module; the second SMA port is connected to the receiving coil, and is used to input the DC pulse signal generated by the DC polarization circuit of the magnetic data acquisition module, and output the Larmor signal to the matching circuit of the magnetic data acquisition module.

[0016] Furthermore, the STM32L051C8T6 chip is used to manage the power switch and the switching of the working mode, and obtains the instructions sent from the host computer through the data storage communication module to switch the working mode of the chip. The working mode is automatically switched according to the set time period and the end cover state, and the switch of each power conversion of the power management module is controlled to control whether the module works or not; specifically, the working modes include the following:

[0017] Low power consumption mode: The system does not need to perform magnetic measurement function, only the timing function needs to be turned on. The specific operation is that the entire system is turned off except for the RTC on the chip, and the power supply is provided by a large-capacity button battery carried extra; Communication mode: Except for the magnetic measurement module and the related magnetic measurement power supply part in the power management module, the rest are in working state; Normal working mode: The STM32L051C8T6 chip controls the relevant magnetic measurement power supply part in the power management module to start, and controls the magnetic measurement module to start working. The acquired magnetic field value is sent by the STM32F407ZGT6 main control chip to the power management module STM32L051C8T6 chip through the serial port. The STM32L051C8T6 chip integrates the timestamp and sends it to the 232 communication circuit of the data communication module for data storage and output instrument.

[0018] In one working cycle, the three modes are automatically switched to reduce power consumption.

[0019] Preferably, the shielding layer is made of POM material; the shell is made of matte PC material. The battery is a 12VDC, 7Ah lead-acid rechargeable battery from Bosch, which is used to power each module in non-low-power mode. The watertight connector uses the eight-core female end of MCBH8F1 produced by SubConn. The MOS tube is a P-channel MOS tube. The power conversion circuit includes a power conversion chip of model MAX1685EEE+ produced by Analog Devices, a power conversion chip of model MAX887H produced by Analog Devices, and a voltage regulator chip of model LT1054CS8 produced by Analog Devices.

[0020] The above technical solution has the following beneficial technical effects: Through the power management module, the geomagnetic daily variation magnetometer can adjust its working mode according to the current state of the magnetometer and external commands, thereby reducing the overall energy consumption, especially when the daily variation station is not measuring, thereby reducing the overall power cost, and achieving a magnetometer instrument deployment time of at least half a year, thereby reducing deployment and recovery costs and improving operational efficiency. Long-term geomagnetic monitoring magnetic data recording also improves data integrity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the overall module block diagram of the present invention; Figure 2 for Figure 1 Schematic diagram of the structure of the magnetic probe module; Figure 3 It is a schematic diagram of the overall structure of the present invention; Figure 4 It is the work flow chart of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, and to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0023] like Figure 1 As shown, a low-power geomagnetic daily variable magnetometer includes a main body, in which a data storage communication module 1, a power management module 2, a magnetic data acquisition module 3 and a magnetic probe module 4 are arranged. The data storage communication module 1 is connected to the host computer through a short-circuit cap (male head) inserted into the watertight connector (female head) 6 on the end cover of the main body for data transmission, storage and command transmission; communicates with the host computer through a communication protocol, and stores the magnetic field value obtained by the magnetic data acquisition module 3; the data storage communication module 1 is also connected to the power management module 2 through a line, and the power management module 2 is used to convert the battery power into a power supply of different voltages to provide an adaptive power supply for the remaining modules; the power management module 2 can also control the switch of each module by controlling the power switch of different modules. The magnetic probe module 4 obtains the Larmor signal by utilizing the Larmor effect and coil induction. The magnetic data acquisition module 3 obtains the corresponding magnetic field value by measuring the frequency of the obtained Larmor signal.

[0024] The data storage communication module 1 includes a 232 communication circuit, a TF card circuit, a short-circuit cap detection circuit and a button battery. The magnetic field value obtained by the magnetic data acquisition module 3 is stored in the TF card and output to the host computer through the 232 communication circuit. At the same time, the host computer inputs instructions to configure system parameters through the 232 communication circuit.

[0025] When in use, the data storage communication module 1 detects the state of the short-circuit cap on the end face through the MOS tube in the short-circuit cap detection circuit to control the input disconnection of the battery: the short-circuit cap connection is judged by the short-circuit cap plug-in state. The short-circuit cap is an eight-core plug corresponding to the male head of the watertight connector 6, and two cores inside the plug are short-circuited together. The two corresponding cores on the watertight connector 6 are respectively connected to the GND of the short-circuit cap detection circuit and the GND of the button battery. When the short-circuit cap plug is inserted into the watertight connector 6, the short-circuit cap detection circuit short-circuits the two GNDs together through the switching action of the MOS, and the button battery forms a loop, which powers the STM32L051C8T6 chip (hereinafter referred to as the L051 chip) and the off-chip RTC clock circuit in the low-power mode, and wakes up the L051 regularly and ensures time continuity. The disconnection of the MOS tube can also be controlled by the I / O pin of the L051 chip inside the power management module 2.

[0026] After the power is turned on, the data storage communication module 1 writes the data and logs into the TF storage card through the 232 communication circuit, and outputs the magnetic field data through the watertight connector 6. It can also transmit the instructions issued by the host computer to configure the system parameters (send instructions to the internal L051 chip).

[0027] The power management module 2 includes an STM32L051C8T6 chip (hereinafter referred to as the L051 chip), a power conversion circuit and a battery. The power management module 2 also includes an external high-speed crystal oscillator (8MHz) circuit, a power circuit (MICRONE's ME6211C3M5G is selected in this embodiment), an off-chip RTC clock circuit (Epson's RX8025T-UC), a debug interface, a reset circuit, a BOOT selection circuit and other peripheral circuits. Other available I / O port resources of the chip are connected through a strip connector.

[0028] In this embodiment, the battery 5 is a 12VDC, 7Ah lead-acid rechargeable battery from BOSCH, which is used to power each module. In this embodiment, the watertight connector 6 is an eight-core female terminal of MCBH8F1 produced by SubConn. The battery 5 is charged by connecting an external power adapter through the watertight connector 6 on the end cover of the main body.

[0029] When in use, the L051 chip controls the power switches of different modules, thereby controlling the working order of each module to ensure that each module works reasonably in different working modes; the power conversion circuit converts power supplies of different voltages to provide adaptive power supplies for the remaining modules.

[0030] The STM32L051C8T6 chip is used to manage the power switch and the switching of working modes. It has three main working modes: shutdown mode, low power mode and running mode. These three modes correspond to the three modes of the system (low power mode, communication mode, normal working mode).

[0031] The power conversion circuit and battery can provide 10V, -10V, 5V, -5V, 3.3V power. The 3.3V power supply is used to power the main control unit of the magnetic data acquisition module, and the remaining power is mainly used for signal processing. The button battery is used to maintain the external RTC clock and L051 chip in low power mode.

[0032] In this embodiment, the power conversion circuit includes a power conversion chip of model MAX1685EEE+ produced by Analog Devices, a power conversion chip of model MAX887H produced by Analog Devices, and a voltage regulator chip of model LT1054CS8 produced by Analog Devices.

[0033] The MAX1685EEE+ chip outputs 10V and 3.3v power supplies. The chip has multiple modes, and the mode selection is based on the chip's pin configuration (configure its STBY pin to a low level and its VBOOT level to a high level). Due to low power consumption requirements, its low power consumption mode is selected.

[0034] MAX887H is a high-efficiency, step-down DC-DC converter: the chip accepts 3.5V to 11V input, provides 1.25V to 10.5V adjustable output, and provides 600mA current; its output voltage can be selected according to the set output resistance. The MAX887H chip steps down the 10V voltage to 5V to obtain a 5V power supply.

[0035] Through the LT1054CS8 voltage regulator chip, 10V and 5V are converted into negative voltage through a charge pump converter to obtain -10V and -5V power supplies.

[0036] The front-end input end of each voltage generating circuit is connected to the I / O port of the L051 chip through a MOS tube. The L051 chip controls whether the target voltage is generated through the MOS tube and controls the power on and off.

[0037] The MOS tube is a P-channel MOS tube, and the control pins of the MOS tube are all connected to the I / O port of the L051 chip.

[0038] The L051 chip selects to turn on part of the power supply or turn off the power supply according to the current state, thereby turning off or on the magnetic data acquisition module 3 and reducing the power loss.

[0039] The magnetic data acquisition module 3 includes an STM32F407ZGT6 main control chip (hereinafter referred to as an F407 chip), an AC polarization circuit, a DC meter polarization circuit, a tuning circuit and a signal detection circuit.

[0040] The power management module 2 provides a 10V power supply for the AC polarization circuit. The AC polarization circuit outputs an AC high-frequency signal. The output terminal of the AC polarization circuit is connected to the signal input terminal of the magnetic probe module 4. The input terminal of the AC polarization circuit is connected to the I\O port of the F407 chip through a MOS tube. The F407 chip controls the operation and operation timing of the AC polarization circuit through the MOS tube.

[0041] The power management module 2 provides a 5V power supply for the DC meter polarization circuit, and the DC meter polarization circuit outputs a DC 5V voltage signal to provide a DC pulse signal for the magnetic probe module 4. The input end of the DC meter polarization circuit is connected to the I\O port of the F407 chip through a MOS tube, and the F407 chip controls the operation and working sequence of the DC meter polarization circuit through the MOS tube.

[0042] The tuning circuit includes eight capacitor arrays, each of which is connected to the I\O port of the F407 chip through a MOS tube. The F407 chip controls the switch of each capacitor array through a MOS tube. The tuning circuit filters and narrowband amplifies the received Larmor signal by selecting a suitable capacitor array.

[0043] The signal detection circuit performs program-controlled amplification and filtering on the signal processed by the matching circuit. The amplified signal is then divided into two paths. One path is the AD voltage acquisition value to obtain the signal strength, and the other path is input to the advanced timer pin of the F407 chip through the square wave conversion circuit to obtain the signal frequency.

[0044] like Figure 2 As shown, the magnetic probe module 4 includes a sample chamber 7, a high-frequency excitation coil 8, a receiving (polarization) coil 9, a shielding layer 10 and a shell 11. The sample chamber 7 is a glass container, which contains a free radical solution (the solution substance is 4-Oxo-TEMPO), and the high-frequency excitation coil 8 is wound around the sample chamber 7. The sample chamber 7 is arranged in a frame 12 wound with a DC excitation and signal receiving coil 9, and the frame 12 is made of insulating material; a shielding layer 10 made of metal material is arranged outside the DC excitation and signal receiving coil 9 to shield the influence of external electromagnetic interference on the resonant cavity and the receiving coil.

[0045] In this embodiment, the material of the shielding layer 10 is POM. POM material is not easy to deform during mechanical processing and can adapt to the temperature range of -40 to 100°C. Its strength, oil resistance and geometric stability can meet the requirements. The shell 11 is made of matte PC material, which is used to encapsulate and fix the magnetic probe module. The end cover of the shell is provided with a first SMA port 13 and a second SMA port 14. The first SMA port 13 is connected to the high-frequency excitation coil 8 for inputting the high-frequency excitation signal generated by the AC polarization circuit of the magnetic data acquisition module 3; the second SMA port 14 is connected to the receiving (polarization) coil 9 for inputting the DC pulse signal generated by the DC polarization circuit of the magnetic data acquisition module 3, and outputting the Larmor signal to the matching circuit of the magnetic data acquisition module 3.

[0046] like Figure 3 and Figure 4 As shown, when used: The eight-core female end of the watertight connector of the main body end cover has two cores connected to the GND of the button battery inside the instrument and the GND of L051 (the core connected to the GND of L051 is called S_A). When the plug (short cap) is not connected, the entire instrument is in a power-off state and does not work. When the instrument end cover is connected to the eight-core male plug cap or the eight-core debugging cable, the two cores of the end cover will be short-circuited together, so that S_A will be connected to the button battery GND in the instrument, and the L051 chip of the instrument power management module will be powered on and start working.

[0047] When powered on for the first time, the L051 chip enters the communication mode (CMDMODE) by default. In this mode, L051 switches the power supply to the rechargeable battery by controlling the MOS tube switch, and only turns on some power switches.

[0048] The host computer initializes the L051 chip through the debugging cable (inserted into the watertight connector), and sends instructions to L051 through the serial port line in the debugging cable to configure time synchronization, SD card data download, SD card data clearing, measurement cycle configuration and other operations. After the instructions are sent or there are no instructions, the L051 chip first reads the default configuration in the TF card of the data storage communication module, and then initializes according to the instructions or default configuration. After initialization, wait for 1 minute. If L051 does not receive any instructions within this 1 minute, L051 will enter the normal working mode (RUNMODE).

[0049] In the normal working mode (RUNMODE), the L051 chip turns on the 3.3V power supply of the main control chip F407 of the magnetic measurement module, as well as the 10V, -10V, 5V, and -5V positive and negative power supplies required by the magnetic measurement module. The main control chip F407 of the magnetic measurement module will control each unit of the magnetic measurement module to start working and complete a magnetic field test.

[0050] The magnetic field test process is as follows: The main control chip F407 of the magnetic data acquisition module 3 controls the AC polarization circuit to generate a high-frequency signal of 60.7 MHz, which is transmitted to the high-frequency excitation coil 8 inside the probe through the first SMA port 13 of the magnetic probe module 4; under the excitation of the high-frequency signal with a frequency of 60.7 MHz, the free radical solution in the probe sample chamber 7 is polarized in a high-energy state; the F407 chip controls the DC polarization circuit to generate a DC pulse signal at a fixed time, and the signal transmits a DC pulse to the receiving (polarization) coil 9 inside the probe through the second SMA port 14 of the magnetic probe module 4. At this time, the free radical solution in the probe sample chamber undergoes an OVERHAUSER effect in a high-energy state, so that the receiving (polarization) coil 9 receives the Larmor signal, which is output to the magnetic data acquisition module 3 through the second SMA port 14.

[0051] Then, the F407 chip turns on the measurement switch, and the Larmor signal is connected to the relevant signal processing circuit and first passes through the tuning circuit. The tuning circuit will perform a preliminary analysis of the Larmor signal through the capacitance scanning program written inside the F407 chip. Different capacitance value channels will have different amplification effects on the Larmor signal. After frequency selection and amplification, the A / D converter will collect the signal voltage value (reflecting the signal strength). The capacitance value with the largest signal strength is the most suitable capacitance value. F407 sets the capacitance value of the fixed tuning circuit. At this point, the A / D converter stops working. After the initial amplification, the signal is amplified by the process control, and the attenuated sine wave is converted into a square wave by the shaping circuit. The main control chip then measures the frequency of the signal to obtain the frequency of the signal, and converts the calculated frequency value into the corresponding magnetic field value through the following formula: , where B represents the magnetic field strength value and v represents the signal frequency.

[0052] It takes about 1 second to complete a magnetic measurement. After completing the magnetic measurement, the F407 chip of the magnetic measurement module sends the magnetic field modulus value to the L051 chip. The L051 chip sends the magnetic field modulus value and time at this time to the data storage communication module. The module saves the data to the TF card and sends it to the 232 serial port line of the debug cable. After completing this operation, L051 enters low power consumption mode (STOPMODE) for the remaining cycle time.

[0053] In low power mode (STOPMODE), the L051 chip of the power management module will actively switch the power supply. The L051 chip controls the power supply of L051 and the external RTC to switch from lead-acid battery power supply to button battery power supply, turn off other power switches, and set the external RTC timer wake-up time, the duration is the remaining cycle duration, and set the L051 chip serial port wake-up and external trigger wake-up. After the setting is completed, all the settings inside the L051 chip are saved in the TF card. In this mode, the L051 chip will only be awakened in two cases: 1. The external RTC reaches the set time to trigger the L051 chip. 2. Any command on the serial port line is transmitted to the L051 chip, and any command is called a wake-up frame.

[0054] According to the different ways of triggering the wake-up, the L051 chip will control the system to enter different modes. If it is an off-chip RTC timer wake-up, the system will switch all power supplies to the lead-acid battery by L051, and turn on all power switches, then directly enter the normal working mode (RUNMODE), complete a magnetic measurement function, and then enter the low power mode (STOPMODE) again, and so on. If the system is awakened by the awakening frame, L051 will switch all power supplies to the lead-acid battery, and only turn on some power switches. L051 will enter the communication mode (CMDMODE), and then wait for 1 minute. If there is no instruction, it will read the configuration information in the TF card of the data storage communication module, and turn on all power switches, then directly enter the normal working mode (RUNMODE), and complete a magnetic measurement function, and then enter the low power mode (STOPMODE) again, and so on.

[0055] In low power mode (STOPMODE), the system does not need to perform magnetic measurement, only the timing function needs to be turned on. The specific operation is that the entire system is turned off except for the external RTC, which is powered by an additional large-capacity button battery. The external RTC has two main functions: 1. Recording time 2. Timed wake-up of the power management module L051. At this time, the overall power consumption is the lowest, and the power consumption is approximately zero (the measured power consumption is 2.4uW).

[0056] In the communication mode (CMDMODE), except for the magnetic measurement module and the related magnetic measurement power supply part in the power management module, the rest are in working state. At this time, the overall power consumption is still relatively low, about 0.01W. At this time, L051 can receive and parse the instructions sent from the outside, and can also control the on-off state of the power supply in the system.

[0057] In the normal working mode (RUNMODE), the L05 chip 1 controls the relevant magnetic measurement power supply part in the power management module to start, and controls the magnetic measurement module to start working. The acquired magnetic field value is sent by the main control chip F407 to the main chip L051 of the power management module through the serial port. The L051 chip integrates the timestamp and sends it to the 232 chip of the data communication module for data storage and output instrument. At this time, the overall system power consumption is the highest, about 0.7W.

[0058] In one cycle, the normal operating mode occupies one second of the cycle, and the low power mode occupies almost the rest of the cycle, thereby achieving the function of reducing power consumption.

[0059] When the working cycle is set to 1 minute, the overall average power consumption is approximately equal to 0.13mW.

Claims

1. A low-power geomagnetic diurnal magnetometer, comprising a main body, Features: The main body is provided with a data storage communication module, a power management module, a magnetic data acquisition module and a magnetic probe module; the data storage communication module is connected to the host computer through the short-circuit cap and the watertight connector on the end cover of the main body, communicates with the host computer through the communication protocol, and stores the magnetic field value obtained by the magnetic data acquisition module; the data storage communication module is also connected to the power management module through the line, and the power management module is used to convert the battery power into a power supply of different voltages to provide an adaptive power supply for the remaining modules; the power management module can also control the switch of each module by controlling the power switch of different modules; the magnetic probe module obtains the Larmor signal by utilizing the Larmor effect and coil induction; the magnetic data acquisition module obtains the corresponding magnetic field value by measuring the frequency of the obtained Larmor signal; The data storage communication module includes a 232 communication circuit, a TF card circuit, a short-circuit cap detection circuit and a button battery. The magnetic field value obtained by the magnetic data acquisition module is stored in the TF card and output to the host computer through the 232 communication circuit. At the same time, the host computer inputs instructions to configure system parameters through the 232 communication circuit; a MOS tube is set in the short-circuit cap detection circuit, and the MOS tube is used to detect the state of the short-circuit cap on the end face to control the input disconnection of the battery; the button battery is used to maintain the off-chip RTC clock and the STM32L051C8T6 chip in low power mode; The power management module includes an STM32L051C8T6 chip, an off-chip RTC clock circuit, a power conversion circuit, and a battery; The L051 chip controls the power switches of different modules, thereby controlling the working order of each module to ensure that each module works reasonably in different working modes; the power supply of different voltages is converted through the power conversion circuit and the battery to provide adaptive power for the remaining modules; the front-end input end of each voltage generating circuit is connected to the I / O port of the L051 chip through the MOS tube, and the L051 chip controls whether the target voltage is generated through the MOS tube to control the power on and off; the L051 chip chooses to turn on part of the power supply or turn off the power supply according to the current state, thereby turning off or on the magnetic data acquisition module and reducing the power loss; the battery is charged through the watertight connector on the end cover of the main body and the external power adapter; The magnetic data acquisition module includes an STM32F407ZGT6 main control chip, an AC polarization circuit, a DC meter polarization circuit, a tuning circuit, and a signal detection circuit; The AC polarization circuit outputs an AC high-frequency signal, and the output end of the AC polarization circuit is connected to the signal input end of the magnetic probe module; the input end of the AC polarization circuit is connected to the I\O port of the STM32F407ZGT6 main control chip through a MOS tube, and the STM32F407ZGT6 main control chip controls whether the AC polarization circuit works and the working timing through the MOS tube; The DC meter polarization circuit outputs a DC voltage signal to provide a DC pulse signal for the magnetic probe module; the input end of the DC meter polarization circuit is connected to the I\O port of the STM32F407ZGT6 main control chip through a MOS tube, and the STM32F407ZGT6 main control chip controls the operation and working timing of the DC meter polarization circuit through the MOS tube; The tuning circuit includes multiple capacitor arrays, each of which is connected to the I\O port of the STM32F407ZGT6 main control chip through a MOS tube, and the STM32F407ZGT6 main control chip controls the switch of each capacitor array through the MOS tube; the tuning circuit filters and narrowband amplifies the received Larmor signal by selecting a suitable capacitor array; The signal detection circuit performs program-controlled amplification and filtering on the signal processed by the matching circuit. The amplified signal is then divided into two paths. One path is the AD acquisition voltage value to obtain the signal strength, and the other path is input to the advanced timer pin of the STM32F407ZGT6 main control chip through the square wave conversion circuit to obtain the signal frequency. The magnetic probe module includes a sample chamber, a high-frequency excitation coil, a receiving coil, a shielding layer and a shell; the sample chamber is a glass container containing a free radical solution, and a high-frequency excitation coil is wound outside the sample chamber; the sample chamber is arranged in a frame wound with a DC excitation and signal receiving coil, and the frame is made of insulating material; a shielding layer made of metal material is arranged on the outside of the DC excitation and signal receiving coil, which is used to shield the influence of external electromagnetic interference on the resonant cavity and the receiving coil; a first SMA port and a second SMA port are arranged on the end cover of the shell, the first SMA port is connected to the high-frequency excitation coil, and is used to input the high-frequency excitation signal generated by the AC polarization circuit of the magnetic data acquisition module; the second SMA port is connected to the receiving coil, and is used to input the DC pulse signal generated by the DC meter polarization circuit of the magnetic data acquisition module, and output the Larmor signal to the matching circuit of the magnetic data acquisition module.

2. The low-power geomagnetic diurnal variation magnetometer according to claim 1, Features: The STM32L051C8T6 chip is used to manage the switch of the power supply and the switching of the working mode. The instruction sent from the host computer is obtained through the data storage communication module to switch the working mode of the chip; the working mode is automatically switched according to the set time period and the end cover state, and the switch of each power conversion of the power management module is controlled to control whether the module works or not; the specific working modes include the following: Low power consumption mode: The system does not need to perform magnetic measurement function, only the timing function needs to be turned on. The specific operation is that the entire system is turned off except for the RTC on the chip, and the power supply is provided by a large-capacity button battery carried extra; Communication mode: Except for the magnetic measurement module and the related magnetic measurement power supply part in the power management module, the rest are in working state; Normal working mode: The STM32L051C8T6 chip controls the relevant magnetic measurement power supply part in the power management module to start, and controls the magnetic measurement module to start working. The acquired magnetic field value is sent by the STM32F407ZGT6 main control chip to the power management module STM32L051C8T6 chip through the serial port. The STM32L051C8T6 chip integrates the timestamp and sends it to the 232 communication circuit of the data communication module for data storage and output instrument; In one working cycle, the three modes are automatically switched to reduce power consumption.

3. The low-power geomagnetic diurnal variation magnetometer according to claim 1, Features: The shielding layer material is POM material.

4. The low-power geomagnetic diurnal variation magnetometer according to claim 1, Features: The shell is made of matte PC material.

5. The low-power geomagnetic diurnal variation magnetometer according to claim 1, Features: The battery is a 12VDC, 7Ah lead-acid rechargeable battery from Bosch, which is used to power each module in a non-low power consumption mode.

6. The low-power geomagnetic diurnal variation magnetometer according to claim 1, Features: The watertight connector adopts the eight-core female end of MCBH8F1 produced by SubConn Company.

7. The low-power geomagnetic diurnal variation magnetometer according to claim 1, Features: The MOS tube is a P-channel MOS tube.

8. The low-power geomagnetic diurnal variation magnetometer according to claim 1, Features: The power conversion circuit includes a power conversion chip of model MAX1685EEE+ produced by Analog Devices, a power conversion chip of model MAX887H produced by Analog Devices, and a voltage regulator chip of model LT1054CS8 produced by Analog Devices.

Images