High-precision multi-path automatic weather station air pressure calibrating instrument
Technical field
The utility model relates to a kind of air pressure calibrating instrument, particularly relates to a kind of high-precision multi-path automatic weather station air pressure calibrating instrument, belongs to meteorologic instrument measurement verification field.
Background technology
At present, there are CAWS600 type, WP3103, ZQZ series etc. in the automatic weather station of China's main flow, the PTB220 that the general baroceptor used is Vaisala company of Finland, its principle is in-built electrical capacitive pressure transmitter, atmospheric pressure change causes capacitance variations, measured by the RC oscillatory circuit of a high precision that oscillation frequency is counter pushes away electric capacity and atmospheric pressure value, and PTB220 can adopt RS232 form, tripping pulse and analog voltage three kinds of multi-form electrical signal to represent atmospheric pressure value.
Baroceptor PTB220 in the automatic weather station of CAWS600 type generally adopts analog voltage (0-5V) to export. Collector is measured magnitude of voltage and is converted into air pressure.
Baroceptor PTB220 in the automatic weather station of WP3103 type generally adopts tripping pulse to export. Collector before each measurement, first sends triggering signal to PTB220, and after PTB220 receives this triggering signal, output quantity is directly proportional to air pressure size, the pulse of frequency 5kHz, dutycycle 50%. Collector pulse count is also converted into atmospheric pressure value.
Baroceptor PTB220 in the automatic weather station of ZQZ series generally adopts RS232 form character string to export. Air pressure numerical value is sent to collector with character string forms with fixing baud rate by baroceptor PTB220. Collector receives character string by RS232 and measures atmospheric pressure value.
But, automatic weather station is placed in field work for a long time, affects by severe environment, and the performance of its collector can decline, and measuring error increases. Meteorological phenomena measurement personnel need regularly the collector of automatic weather station to be carried out on-site proving. The calibrating of collector pressure channel needs the air pressure signal source of a standard, and energy Simulated gas pressure sensor PTB220 exports the electrical signal of three kinds of forms, and the scope of signal is consistent with PTB220 with feature.The output signal in air pressure signal source measured by collector, by observed value with set(ting)value comparison, judges the measurement performance of acquisition device in weather station pressure channel.
At present, the instrument examined and determine for acquisition device in weather station pressure channel extremely lacks. General electronic measuring instrument function generator, can provide analog voltage signal, but output area and resolving power do not meet the requirement of CAWS600. Electrical signal required during WP3103 and ZQZ series calibrating is then more special, it does not have meet the signal source required. In addition, still there is output electrical signal form single in the automatic weather station signal simulator of the existing air pressure signal that can provide RS232 form, can not take into account the deficiency of the automatic weather station of different model.
Practical novel content
Main purpose of the present utility model is, overcomes deficiency of the prior art, it is provided that the high-precision multi-path of a kind of novel texture automatic weather station air pressure calibrating instrument, is specially adapted to the calibrating of different model automatic weather stations pressure channel.
Technical problem to be solved in the utility model is to provide easy, safe and reliable, the practical high-precision multi-path automatic weather station air pressure calibrating instrument of compact construction, easy accessibility, making, the air pressure signal exporting analog voltage, tripping pulse, RS232 form respectively from three passages can be realized, output electrical signal scope and resolving power can be mated from the collector of the automatic weather station of different model, and the output high precision of three kinds of signals, do not interfere with each other, have the utility value in industry.
In order to achieve the above object, the technical scheme that the utility model adopts is:
A kind of high-precision multi-path automatic weather station air pressure calibrating instrument, comprise principal controller, the parameter memory module that is all connected with principal controller, control button, reset circuit, clock circuit, RS232 serial port circuit, CPLD module and D/A transmodulator, and power consumption source and be mounted on the information display module of CPLD module expansion delivery port.
Wherein, the output terminal of described RS232 serial port circuit is connected with RS232 rs 232 serial interface signal and exports interface, described CPLD module is by receiving the triggering signal from automatic weather station with fixed frequency output pulse signal in output of pulse signal interface, and described D/A transmodulator is nursed one's health circuit by amplifier and is connected with analog signals and exports interface; Described RS232 rs 232 serial interface signal exports interface, output of pulse signal interface and analog signals and exports interface all for being connected with the data acquisition unit of automatic weather station.
The utility model is set to further: be provided with bus isolation circuit between described principal controller and D/A transmodulator.
The utility model is set to further: described bus isolation circuit is the digital isolator ADUM1401 of four-way.
The utility model is set to further: carry out isolated from power by the DC-DC chip MEB01Z-05S05D of low ripple between two working power interfaces in the digital isolator ADUM1401 of described four-way.
The utility model is set to further: described principal controller adopts MSP430 series monolithic to make.
The utility model is set to further: described MSP430 series monolithic is built-in with UART module.
The utility model is set to further: described UART module is two, and it is that RS232 level is exported to RS232 rs 232 serial interface signal and exported interface that described MSP430 series monolithic is exported TTL level conversion after TTL level by electrical level transferring chip max232 by any one built-in UART module.
The utility model is set to further: described D/A transmodulator adopts AD5660 chip, described amplifier conditioning circuit adopts LTC2050 chip, and described amplifier conditioning circuit provides votage reference by a reference source ADR421 after UPR type electric resistance partial pressure and provides negative electricity source by electric charge pump flip-chip LTC1983-5.
The utility model is set to further: described parameter memory module adopts eeprom chip.
The utility model is set to further: described power supply is lithium cell, and described information display module is TFT display screen.
Compared with prior art, the useful effect that the utility model has is:
According to the transformational relation of atmospheric pressure value and three kinds of electrical signal, make full use of the advantage of CPLD resume module digital timing circuit, micro-chip is adopted to add the framework of CPLD module, and it is aided with parameter memory module, information display module etc., realize exporting high precision from three passages respectively, the analog voltage not interfereing with each other, tripping pulse, the air pressure signal of RS232 form, output electrical signal scope and resolving power can be mated from the collector of the automatic weather station of different model, for on-site proving and the breakdown judge of different model acquisition device in weather station pressure channel provides a kind of comprehensive instrument means.
Foregoing is only the general introduction of technical solutions of the utility model, and in order to more clearly understand technique means of the present utility model, below in conjunction with accompanying drawing, the utility model will be further described.
Accompanying drawing explanation
Fig. 1 is the structural representation of the utility model high-precision multi-path automatic weather station air pressure calibrating instrument;
Fig. 2 is the schematic circuit that the utility model high-precision multi-path automatic weather station air pressure calibrating instrument produces the air pressure signal of tripping pulse form;
Fig. 3 is the schematic circuit that the utility model high-precision multi-path automatic weather station air pressure calibrating instrument produces the air pressure signal of analog voltage form;
Fig. 4 is the schematic circuit that the utility model high-precision multi-path automatic weather station air pressure calibrating instrument produces the air pressure signal of RS232 form;
Fig. 5 is the bus isolation circuit of the utility model high-precision multi-path automatic weather station air pressure calibrating instrument;
Fig. 6 is the isolated from power circuit of the utility model high-precision multi-path automatic weather station air pressure calibrating instrument.
Embodiment
Below in conjunction with Figure of description, the utility model is further described.
The automatic weather station of a kind of high-precision multi-path as shown in Figure 1 air pressure calibrating instrument, comprise principal controller, the parameter memory module that is all connected with principal controller, control button, reset circuit, clock circuit, RS232 serial port circuit, CPLD module and D/A transmodulator, and power consumption source and be mounted on the information display module of CPLD module expansion delivery port; The output terminal of described RS232 serial port circuit is connected with RS232 rs 232 serial interface signal and exports interface, described CPLD module is by receiving the triggering signal from automatic weather station with fixed frequency output pulse signal in output of pulse signal interface, and described D/A transmodulator is nursed one's health circuit by amplifier and is connected with analog signals and exports interface; Described RS232 rs 232 serial interface signal exports interface, output of pulse signal interface and analog signals and exports interface all for being connected with the data acquisition unit of automatic weather station.
For ease of on-site proving, adopting lithium battery power supply mode, select the principal controller of treater as system of low-power consumption, for producing the air pressure signal of RS232 form, principal controller is preferably built-in with UART module. Consider, the MSP430 series monolithic of TI company of low-power consumption can be selected as principal controller.And the air pressure signal of high-precision analog voltage form is produced by 16 DAC, isolating device and signal conditioning circuit, and tripping pulse form is realized by CPLD module. Current output pressure value and corresponding electrical signal size are shown by TFT screen display. TFT screen takies more I/O port, directly should not drive by the principal controller of micro-chip form, the expansion I/O port of CPLD module can be utilized to mount. Adopt eeprom chip as parameter memory module, for storing the conversion function relation of air pressure and electrical signal, temperature compensation parameter etc.
As depicted in figs. 1 and 2, when examining and determine the collector pressure channel of the automatic weather station of WP3103, it is necessary to calibrating instrument can provide the air pressure signal of tripping pulse form, and the sequential of tripping pulse is completely the same with baroceptor PTB220. The CPLD module adopted realizes sequential circuit and has the advantage that resource is abundant, precision is high, and EPM240T100C5 can be utilized to produce the air pressure signal of tripping pulse form.
As shown in Figure 2, input terminus TRI receives the triggering signal that collector is sent, and input terminus DATA and WR is the communication port of principal controller and CPLD, and umber of pulse N corresponding for atmospheric pressure value is sent to CPLD by DATA by principal controller. The 50MHz clocksignal that input terminus f50M provides for crystal oscillator. Output terminal PULSE exports the pulse of N number of frequency 5kHz, represents that air pressure size is (N*0.1) hPa.
Device mcu_interface is the interface circuit of CPLD module and principal controller, and DATA is 8 bit data bus, and WR is communications control signal. Air pressure to produce is 500hPa, then calibrating instrument is after receiving triggering signal, it is necessary to producing 5000 frequencies is the pulse of 5kHz. Integer 5000 is write the device mcu_interface of CPLD module by principal controller by bus DATA, and delivers to port Num [15..0] and export.
Device f_DIV_5kHz is frequency divider, and the clock division of 50MHz obtains the pulse signal of 5kHz. Device Presure_Plus produces the number that enable signal EN, EN export pulse by Sheffer stroke gate NAND2 control. When TRI does not receive triggering signal, EN keeps lower level, exports PULSE and is always high level. TRI detects that the triggering signal negative edge that collector is sent starts, it is desired to export pulse after time delay 20ms again. Therefore variable x, x are set in device Presure_Plus to the pulse counting of 5kHz, when counting down to 100 from 0, EN keeps lower level, and output terminal PULSE is high level. Recurrence interval is 0.2ms, 100 pulses and time delay 20ms. When x count down to (N+100) from 100, EN keeps high level, and the pulse of 5kHz is exported by PULSE end by Sheffer stroke gate. It is 500-11000 that the N number of pulse received is converted into the span of atmospheric pressure value (N*0.1) hPa, N by collector.
As shown in figures 1 and 3, according to the feature of analog voltage form air pressure signal, after setting atmospheric pressure value, calibrating instrument exports volts DS, and the scope producing analog voltage is 0-2.5V. For improving the precision of output voltage, low temperature drift voltage benchmark, high precision DAC, extremely low imbalance amplifier can be adopted to design circuit. In Fig. 3, utilize the D/A conversion chip AD5660 of 16 to produce interface that analog voltage U1, bus DIN, CLK, CS are itself and principal controller. AD5660 is that 16 low-power consumption of ADI company, single passage, buffering voltage export DAC, built-in 1.25V benchmark. Adopt a reference source ADR421 with permanent stability to export the votage reference of 2.5V, obtain voltage U 3 by the UPR type resistance R2 of pole low temperature drift (2ppm/ DEG C) and R4 dividing potential drop.U1 and U3, after the subtraction circuit being made up of the amplifier LTC2050 of pole low maladjustment voltage (maximum 3 μ V), obtains output voltage U4, and U4 is the air pressure signal meeting the voltage form required. LTC1983-5 shown in Fig. 3 is electric charge pump flip-chip, can be amplifier and provides negative electricity source.
As shown in Figure 1 and Figure 4,430 series monolithics that native system adopts can be built-in with two UART modules, utilizes UART0 wherein to produce the air pressure signal of serial port form, and the baud rate that the automatic station of ZQZ series receives RS-232 form air pressure signal is 2400. The Configuration of baud rate of UART0 is 2400 by initialization register. The UART0 of micro-chip exports as TTL level, utilizes electrical level transferring chip max232 to be converted into RS232 level; Wherein MCU-TXD0, MCU-RXD0 are connected with the UART0 of micro-chip, and the air pressure signal that XD, RXD export is connected with the collector of automatic weather station. D1 and D2 is the transition diode of electrostatic protection.
Native system is as the calibrating instrument of acquisition device in weather station pressure channel, it is desired to the limits of error of output pressure signal are less than the 1/3 of collector measuring error. The air pressure signal of RS232 and pulse form is digital quantity, and immunity from interference is strong. And the generation circuit of the air pressure signal of analog voltage form is very easily subject to the interference of envrionment temperature, digital path. Except focusing on parts selection, outside selecting high precision DAC, low imbalance amplifier, the measures such as isolation, compensation also can be taked to ensure the high precision of output signal.
As shown in Figure 5, it is Bus isolation measure, for the loop of the air pressure signal generation circuit and digital path that make analog voltage form is completely independent. Prevent the flowing of electric current between principal controller and DAC communication nodes, channel separation must be carried out. Native system selects the digital isolator ADUM1401 of four-way iCoupler technology by the communication bus isolation of principal controller and DAC, wherein, VDD1, GND1 are the VDD-to-VSS of digital path, CS, CLK, DIN be connected with master control sheet choosing, clock, data bus, VDD2, GND2 are the VDD-to-VSS of analog voltage passage, G-CS, G-CLK, G-DIN be isolation after with analog voltage produce circuit DAC5660 be connected sheet choosing, clock, data bus.
As shown in Figure 6, it is isolated from power measure, the DC-DC chip MEB01Z-05S05D of pole low ripple can be selected the working power VDD1 and VDD2 of four-way digital isolator ADUM1401 to be isolated. The input voltage of device MEB01Z has wider span: 4.75-5.25V, and its ripple £ 10mV, output voltage 5V, and outward current reaches 200mA, power 1W, so meeting the power consumption requirement of voltage generating module completely.
Innovative point of the present utility model is, can provide the novel air pressure calibrating instrument that a kind of high precision, hyperchannel (RS-232 form, analog voltage, tripping pulse) export and do not interfere with each other simultaneously. Showing after tested, the air pressure signal scope of three passage outputs is 500-1100hPa, covers the useful range of automatic weather station; Worst error ± 0.02hPa, far below the maximum error of measuring ± 0.3hPa of automatic weather station; Thus the automatic weather station that can be different model provides comprehensive measurement verification.
The above, it it is only better embodiment of the present utility model, not the utility model is done any restriction in form, although the utility model discloses as above with better embodiment, but and be not used to limit the utility model, any those skilled in the art, do not departing within the scope of technical solutions of the utility model, make a little change when the technology contents of above-mentioned announcement can be utilized or it is modified to the equivalent embodiment of equivalent variations, in every case it is the content not departing from technical solutions of the utility model, the any simple modification above embodiment done according to technical spirit of the present utility model, equivalent variations and modification, all still belong in the scope of technical solutions of the utility model.