RU79341U1 - INFORMATION COLLECTION SYSTEM FOR BOTTOM MEASUREMENTS IN THE HIGH FREQUENCY RANGE - Google Patents

Abstract

An information collection system comprising a control unit, a data storage device, a real-time clock, from one to eight measuring units equipped with amplifiers and separate power supplies, is characterized in that a microcontroller operating under the control of a specialized program and equipped with at least one microcontroller is used at least two USART interfaces, one SPI and one I2C, while two FlachCard digital drives of the CD or MMS type connected to the SPI bus are used as an information storage device a switch connected to the ports of the microcontroller and realizing the choice of the first or second drive, in addition, it provides connection to the SPI bus from one to eight galvanically isolated measuring nodes operating from one clock generator, each node containing a measuring signal instrumental amplifier implemented according to the scheme MDM, 24-bit analog-to-digital converter, reference voltage source, power supply and galvanic isolation circuit, in addition to the information collection system Introduced a high-precision real-time clock that exchanges data with the microcontroller via the I2C bus and delivers pulses to the microcontroller with a frequency of 1 Hz and a frequency of 32 kHz for synchronization with UTP, a GPS receiver connected to the USART0 bus and a device are also included in the data acquisition system for connecting a GPS receiver, containing galvanic isolation, a converter of electrical signal levels to the RS-232 protocol, a reference voltage source and a power source, and the second pulse is provided s from GPS to the microcontroller port, in addition, an information collection system for exchanging data and commands with an external device via the USART1 bus,

includes a node, which includes galvanic isolation, an electrical signal level converter for the RS-232 protocol and a voltage stabilizer, also provides a sealed version of the information collection system allowing immersion to depths of up to 200 meters. Using the claimed device provides the following features of digital registration: 1. simultaneous digital voltage recording with 8 channels having a capacity of 24 bits; the channels are completely galvanically isolated, each channel has a separate power source; 2. The volume of the digital storage device can be more than 16 GB; 3. The accuracy of synchronization with a connected data transmission node with GPS and conditions ensuring the regular operation of the GPS receiver is 1/32000 seconds; when the data node with GPS is off, the synchronization error is determined by the temperature and pressure of the environment and can be reduced due to statistical estimates from a series of observations when the data node with GPS is connected; 4. when using the AD7793 ADC chip, the sampling frequency is in the range 4.17-470 Hz, the measured voltage is pseudo bipolar mode, the minimum ADC noise is 40 nV and depends on the environment, the maximum input voltage range is ± 2.5 V; 5. when using the chip of the instrument amplifier AD8535, the input signal gain can, when mounting the board, be set from 0.1 to 10000, the maximum input voltage range is ± 2.5 V.

Description

The utility model relates to technical means, long-term autonomous recording of voltage in the ultra-low frequency range (0.000001-1000 Hz) in sea conditions, with a depth of up to 200 m. The utility model is intended for long-term autonomous digitization and signal accumulation, in the ultra-low frequency range, from high - or low impedance sensors sunk to the bottom. In particular, the device can be used as a digital recorder for measuring physical fields of various nature in bottom measurements: temperature, pressure, telluric currents, magnetic field, seismic signals, low-frequency acoustic signals; the mode of both short-term and monitoring observations is allowed.

Known research and development of an autonomous single-channel system for collecting, processing, storage and transmission of information about slowly changing processes, focused on bottom measurements - ELIS-3, containing: instrumentation amplifier AD627, ADC AD7714, microcontroller AT90S8515 from Atmel, flash memory series AT45 Atmel (see the description of the ELIS-3 system, manufactured by IZMIRAN, Gaydash S.P. Marine electromagnetic research: creation of instrumental and methodological support, experiment, results // Abstract of Cand. diss. Phys. -mat. of sciences, Troitsk, 2007).

The disadvantages of the known technical means are: a small amount of memory for storing data, the use of an instrument amplifier AD627, the lack of a synchronization system, the presence of one digital channel. The AT45 series flash memory has a maximum capacity of 8 MB (when registering a 24-bit channel with a frequency of 10 Hz, the time

registration is limited to 75 days), which is insufficient to record additional information (GPS synchronization) or to conduct long-term monitoring sessions. The AD627 instrumental amplifier is implemented according to the “classical” scheme, which implies a significant zero trend for long periods, in contrast to the “modulation-demodulation” (MDM) scheme. The ELIS-3 technical tool does not provide for a well-developed synchronization system, which can lead to significant time shifts during long-term autonomous observations; Thus, for a harmonic signal with a frequency of 30 seconds, a synchronization error of 1 second will lead to a significant phase estimation error of 12 degrees.

The four-channel E24 analog-to-digital conversion unit containing four AD7714 analog-to-digital conversion chips and an Atmel microcontroller AT90S2313 microcontroller is known (see description of the E24 block manufactured by L-Card CJSC: www.lcard.ru). The disadvantage of this solution is the lack of internal memory, which necessitates the permanent connection of the E24 to an external device for storing data (for example, a computer), as well as the absence of full galvanic isolation of the measuring channels, which makes it impossible to use more than one channel when measuring in a low-resistance marine environment (apparent resistance of the order of 0.3 Ohm · m).

The objective of the utility model is to increase the capabilities and reduce the cost of observations performed during long-term autonomous detection of voltage in the ultra-low frequency range by improving the technical characteristics and design features of the technical means: increasing the amount of memory for storing data; the use of instrumental amplifier implemented according to the MDM scheme; complement the device with a hardware-software circuit for synchronizing observations

using, as a reference for synchronization and collection of statistics, a GPS signal; creating a multi-channel system, with completely galvanically isolated channels.

The technical result achieved in solving the problem is expressed in increasing the time of autonomous observations, increasing the stability of zero during super-long-term observations, obtaining a more accurate recording record in time, and the possibility of highly synchronous recording of observations from several different sensors. In addition, the claimed device will be particularly effective, due to the use of GPS, in ground-based long-term (monitoring) observations, both in the field and in the observatory.

The problem is solved in that the information collection system comprising a control unit, a data storage device, a real-time clock, from one to eight measuring units equipped with amplifiers and separate power supplies, is characterized in that a microcontroller operating under the control of a specialized microcontroller is used programs and equipped with at least two USART interfaces, one SPI and one I2C, while two FlachCard digital drives of the type CD or MMS are used as storage media connected to the SPI bus, and there is a switch connected to the ports of the microcontroller and realizing the choice of the first or second drive, in addition, it provides connection to the SPI bus from one to eight galvanically isolated measuring nodes operating from one clock generator, and each node contains a tool amplifier the measured signal, implemented according to the MDM scheme, a 24-bit analog-to-digital converter, a voltage reference source, a power source and a galvanic isolation circuit, In addition, a high-precision real-time clock that exchanges data with

the microcontroller via the I2C bus and pulses to the microcontroller with a frequency of 1 Hz and a frequency of 32 kHz for synchronization with UTP, the data acquisition system also includes a GPS receiver connected to the USART0 bus and a device for connecting a GPS receiver containing galvanic isolation, a level converter electrical signals to the RS-232 protocol, a reference voltage source and a power source, moreover, the transmission of second pulses from GPS to the microcontroller port is provided, in addition, an information collection system for exchange annymi and commands with an external device by USART1 bus comprises a node which includes a galvanic isolation transformer levels of electric signals to the RS-232 protocol, and a voltage regulator, is also provided a hermetic execution information collection system allows for immersion depths up to 200 meters.

A comparative analysis of the features of the claimed solutions with the features of the prototype and analogues indicates the compliance of the claimed solutions with the criterion of "novelty."

The combination of features of the utility model formula provides a solution to the problem - increasing the capabilities and reducing the cost of observations performed with long-term autonomous recording of voltage in the ultra-low frequency range by improving the technical characteristics and design features of the technical means: increasing the amount of memory for storing data; the use of instrumental amplifier implemented according to the MDM scheme; supplementing the device with a hardware-software circuit for synchronizing observations using, as a reference for synchronization and statistics, a GPS signal; creating a multi-channel system, with completely galvanically isolated channels.

The claimed utility model is illustrated by drawings: figure 1 shows a diagram of a device; figure 2 shows the timing diagrams used when synchronizing the recording of a signal with UTP.

The drawing of figure 1 shows the control unit 1 (microcontroller), for which there is a connector 2 used for in-circuit programming and emulation, a power source 3 connected by other components of the power bus 4. The real-time clock 5 is connected to the microcontroller 1 by the I2C 6 bus, output clock pulses 7 with a frequency of 1 Hz and an output of clock pulses 8 with a frequency of 32 kHz. Two storage media 9, implemented using a CD or MMS card, are connected to the SPI bus 10, while there is a switch 11, allowing manual switching between drives. The generator 12 sets the clock frequency transmitted via bus 13 to each of the eight measuring nodes 14. In addition, each measuring node includes a galvanic isolation circuit 15, an analog-to-digital converter 16, an instrumentation amplifier 17 to which the measured signal is supplied via line 18, and, after amplification, it enters the analog-to-digital Converter 16 through line 19; in addition, the measuring unit includes a power source 20 and a reference voltage source 21 connected to other components by a power bus 22. On a USART1 bus 23, the microcontroller 1 is connected to a node 24 for exchanging data and commands with an external device via RS-232 protocol; the node includes a galvanic isolation circuit 25, an electric signal level converter 26 to the RS-232 protocol connected to the external device output connector 27, while the power of the node 24 is supplied from the socket 27 via a line 28 to a voltage regulator 29 and then to the power bus 30. On the USART0 bus 31, the microcontroller 1 is connected to the GPS connection unit 32, which includes a galvanic isolation circuit 33, an electrical signal level converter 34 to the RS-232 protocol, which is connected to the GPS device 35;

the power of the node 32 is provided via the power bus 36 connected to the voltage stabilizer 37, which is connected to the power source 38. The GPS device 35 supplies second pulses along line 39 to the galvanic isolation circuit 33 and, further, to the port of microcontroller 1. In addition, the microcontroller, by connector 40, connected to the input of a specialized device that provides the lifting of the information collection system from the bottom and the supply of signals for its detection. The measuring unit 14 is connected via the connector 41, the node 24 for exchanging data and commands with an external device through the connector 42, the GPS connection unit 32 through the connector 43.

A microcontroller (ATmega164P or another) used under control of a special program and equipped with at least two USART interfaces, one SPI, and one I2C was used as a control unit for information collection system 1. Moreover, a special program provides the following functions:

- interacts through node 24 with an external device, from which it receives commands configuring nodes of the information collection system and setting parameters of the measurement mode;

- sets the mode of operation of the analog-to-digital Converter 16 in each of the nodes 14, provides the reception of digitized values and the transmission of the necessary commands;

- saves the measurement results, in a specific format, on one of the digital media 9, depending on the position of the switch 11 and the set measurement mode;

- allows you to transfer data to an external device through node 24, for visualization (using an external device as a graphical oscilloscope) or saving;

- sets the operating mode of the GPS device, provides data reception from the GPS device via bus 31 and clock pulses along line 39;

- sets the real-time clock 5, provides clock synchronization with the GPS device 35 by synchronizing the pulses received by the microcontroller on lines 7 and 39;

- registers the error of the departure of the real-time clock 5 with the help of lines 7.39 and the output of clock pulses 8 with a frequency of 32 kHz;

- gives an impulse, indicating the completion of registration, to the input 40 of a specialized device that provides the raising of the information collection system from the bottom and the supply of signals for its detection.

At the same time, connecting a special debugging device to connector 2 allows for in-circuit reprogramming of the microcontroller and debugging of the program in emulation mode.

As information storage 9 flash cards of the type MMS or CD are used, each up to 8 GB. Depending on the specified measurement mode, the drive can be selected:

- manually, using switch 11, with the termination of recording when filling one of the drives;

- automatic filling of both drives with subsequent termination of recording (without overwriting), regardless of the position of the switch 11;

- automatic sequential recording to a subsequent drive when filling in the current (with overwriting) regardless of the position of the switch 11.

Data is stored on the drive in a special format, while registering:

- parameters of the operating mode of the information collection system, including the configuration of each measuring unit;

- commands received from an external device during the operation of the information collection system;

- the value of the measured signal from each of the measuring nodes 14 with recording the number of the measuring node;

- the results received from the GPS receiver 35 (with the connected 32 GPS connection node), including the date, time, coordinates and accuracy characteristics for determining the time and coordinates;

- results obtained from real-time clock 5, including date, time, clock drift error, estimated by the difference between the pulses on lines 7 and 39; in this case, pulses with a frequency of 32 kHz, obtained on line 8, are used as a measure.

Digitization of the analog signal 18 from a certain sensor is carried out using the recording unit 14. In this case, the analog signal is fed to the instrumental amplifier 17, designed for registration of low-frequency signals and made according to the MDM scheme (AD8553 or another) and, further, to a 24-bit converter ( AD7793 or another), designed to detect low-frequency signals. Further, the digitized signal is fed through the ralvanic isolation circuit 15 (ADuM1401 or otherwise) to the SPI bus. The clock frequency of the analog-to-digital Converter is set by the generator 12, galvanically isolated from the registration node using a high-speed optocoupler. Each registration node has a separate power supply 20, connected to the power bus 22 through a precision reference voltage source. Thus, the registration node 14 is completely galvanically isolated from other nodes of the information collection system. Connecting from one to eight registration nodes 14 is carried out by means of a connector 41 switching power bus 4, interface bus SPI 10, bus tektovogo frequency analog-to-digital converters 13.

The mode of operation of the information collection system is set from an external control device connected to the connector 27 of the node for exchanging data and commands with an external device; the unit is galvanically isolated and disconnected from the voltage meter and connected to it via a connector 42, switching the power bus 4 and the bus USART1 23. The external device must have

external port that implements data exchange via RS-232; such a device may be, for example, a computer or PDA of the appropriate configuration. The node provides power from an external device supplied through connector 27 and line 28 to a voltage converter 29, the input voltage of which varies from 5 to 18 V, and the output voltage is 5 V. The node also contains a converter of logical levels of KPOP to RS-232 levels (MAX3221 ) In this case, a special program of the external device sets the following parameters of the information collection system:

- the operation mode of the analog-to-digital Converter 16 in each of the nodes 14, including the frequency of signal registration and the coefficient of the built-in ADC amplifier;

- mode of saving measurement results;

- the operating mode of the GPS device 35, including the frequency and duration of the GPS survey;

- gives the command to synchronize the clock 5 with the GPS device 35 and sets the microcontroller 1 synchronization parameters;

- gives a command to transfer data to an external device via node 24, for the purpose of visualization (using an external device as a graphical oscilloscope) or saving;

- Configures the pulse feed mode to input 40.

GPS is connected to the data acquisition system via connector 43 of the switching power bus 4 and the USART0 bus 31 and the line of the second synchronization pulse 39 from the GPS. At the same time, the connection unit of the GPS device has a separate power source 38 connected to the power bus 36 by means of a voltage converter 37. The node is galvanically isolated and disconnected from the information collection system. The node also contains a converter of logical levels KPOP to levels RS-232 (MAX3221) 34 and a GPS device 35. Data is transmitted to the microcontroller

via the USART0 31 bus, while the operation mode of the GPS device is set by the commands of the microcontroller 1 via the USART0 31 bus, according to the commands of an external control device connected to the connector 27.

Time reference during operation of the information collection system is carried out in the following way (figure 2):

1) the leading edge of the second pulse arriving from the real-time clock 5 (RTC) is fixed, relative to which the counting of pulses with a frequency of 32 kHz supplied to the microcontroller via line 7 starts, at the same time, the time by clock 5 is recorded on the data storage 9;

2) one of the following events is fixed

- the arrival of the leading edge of the second pulse along line 39 (Fig. 2, interval t1), from the GPS 32 connection node, if this node is connected to the information collection system, after which the value of the pulse counter 32 kHz is written to the data storage device 9 and, after receiving data , - GPS data;

- the readiness of the ADC 16 for data transfer via the SPI 10 bus (Fig. 2, intervals t2, t3), after which the value of the pulse counter 32 kHz is written to the data storage 9 and, after receiving the data, data from the ADC 16 (for each measuring unit fourteen).

When synchronizing the real-time clock, the real-time clock is set so that the deviation, measured by the 32 kHz counter, is less than 100 pulses by the 32 kHz counter (the synchronization moment is marked in figure 2 - line 1-1 '). In this case, the error in calculating the exact time according to the results of writing to the data storage device 9 will be less than 1/32000 second (figure 2, the interval t0).

Data is recorded from the address of the Flash memory 9, which is set from an external device each time a command for registration is sent via connector 27. Recording begins by writing the “initial” sequence of bytes and a header containing

information about the operating mode of the information collection system. Recording is completed by registering the end sequence of bytes when a command is issued to stop registration from an external device via connector 27. In addition, a format mode for Flash memory 9 is provided, when a command is sent from an external device, writing 0 to all information storage cells; formatting is necessary to search for memory cells of the information storage device when the recording is stopped abnormally and there is no end header (for example, when the power is turned off). Data can be read either by moving the data storage device 9 from the information collection system to the corresponding Flash memory reader or through the connector 27, when a corresponding command is sent from an external device.

The sealing of the information collection system, in bottom studies, is achieved by coating the surface of the printed circuit board and microcircuits with a sealing varnish made on the basis of epoxy resin and placing the register inside a special gondola, immersed in kerosene.

The above description of the circuit (figure 1), the operation mode of individual nodes of the utility model and their functional load reflect the possibility of implementing the utility model.

The achievement of the technical result, which consists in increasing the capabilities and reducing the cost of observations made with long-term autonomous recording of voltage in the ultra-low frequency range, by improving the technical characteristics and design features of the technical means, when implementing a utility model is determined by the following characteristics of components and the results of experimental design work:

1. the volume of the digital storage device is determined by the volume of two Flash Cards and is more than 16 GB, which is 2000 times more than the 8 MB analogue;

2. The claimed device allows simultaneous digital recording of voltage from 8 channels having a capacity of 24 bits; the channels are completely galvanically isolated, each channel has a separate power source;

3. the accuracy of synchronization with a connected node for transmitting data with GPS and conditions ensuring the regular operation of GPS is 1/32000 seconds; when the data node with GPS is off, the synchronization error is determined by the temperature and pressure of the environment and can be reduced due to statistical estimates from a series of observations when the data node with GPS is connected;

4. when using the AD7793 ADC chip, the sampling frequency is in the range 4.17-470 Hz, the measured voltage is pseudo bipolar mode, the minimum ADC noise, according to the documentation, is 40 nV and depends on the environment (according to the results development work - up to 1 μV in conditions of strong electromagnetic noise), the maximum input voltage range is ± 2.5 V;

5. when using the chip of the instrument amplifier AD8535, the input signal gain can, when mounting the board, be set from 0.1 to 10000, the maximum input voltage range is ± 2.5 V.

Claims (1)

An information collection system comprising a control unit, a data storage device, a real-time clock, from one to eight measuring units equipped with amplifiers and separate power supplies, characterized in that a microcontroller operating under the control of a specialized program and equipped with at least one microcontroller is used at least two USART interfaces, one SPI and one I2C, while two FlachCard digital drives of the CD or MMS type connected to the SPI bus are used as an information storage device. The switch is connected to the ports of the microcontroller and implements the choice of the first or second drive, in addition, it provides connection to the SPI bus from one to eight galvanically isolated measuring nodes operating from one clock generator, each node containing an instrumentation amplifier of the measured signal implemented according to the scheme MDM, 24-bit analog-to-digital converter, reference voltage source, power supply and galvanic isolation circuit, in addition, as part of the information collection system In addition, a high-precision real-time clock was introduced that exchanges data with the microcontroller via the I2C bus and sends pulses to the microcontroller with a frequency of 1 Hz and a frequency of 32 kHz for synchronization with UTP, and the GPS-receiver connected to the USART0 bus is also part of the data acquisition system, and a device for connecting a GPS-receiver, comprising galvanic isolation, a converter of electrical signal levels to the RS-232 protocol, a reference voltage source and a power source, and second impu ls from GPS to the microcontroller port, in addition, the information collection system for exchanging data and commands with an external device via the USART1 bus includes a node that includes galvanic isolation, an electrical signal level converter for RS-232 protocol, and a voltage regulator, execution of an information collection system that allows diving to depths of up to 200 m.