CN203148842U - Infrared gas detecting system - Google Patents
Infrared gas detecting system Download PDFInfo
- Publication number
- CN203148842U CN203148842U CN 201320093237 CN201320093237U CN203148842U CN 203148842 U CN203148842 U CN 203148842U CN 201320093237 CN201320093237 CN 201320093237 CN 201320093237 U CN201320093237 U CN 201320093237U CN 203148842 U CN203148842 U CN 203148842U
- Authority
- CN
- China
- Prior art keywords
- circuit
- microprocessor
- output terminal
- temperature control
- distributed feedback
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn - After Issue
Links
Images
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The utility model discloses an infrared gas detecting system, belonging to the technical field of gas detection. The infrared gas detecting system comprises a temperature control circuit, a current drive circuit, a DFB (Distributed Feed Back) laser, a gas chamber, a photoelectric detector, a reference circuit, an amplifying circuit, a digital potentiometer, a differential circuit, a filter circuit and a microprocessor. The infrared gas detecting system is characterized in that the digital potentiometer is used as a gain resistor of the amplifying circuit, the final wave form change collected by the microprocessor is processed by software and the resistance value of the digital potentiometer is fed back and regulated to change the enlargement factor of an electric signal of a transmission light path so as to automatically compensate the light power fluctuation of transmission light passing the gas chamber, caused by environmental factors (except gas adsorption), and the system measurement error caused by the light power fluctuation is overcome. The infrared gas detecting system disclosed by the utility model is simple in structure, easy to realize, high in long-term stability and non-sensitive to a system environment, thereby being capable of being extensively applied to the field of free light path detection and optical fiber gas detection.
Description
Technical field
The utility model relates to a kind of infrared gas detection system, belongs to the gas detection technology field.
Background technology
The detection of micro-water content has important effect in power industry.Since the mid-80, along with developing rapidly of power industry, sulfur hexafluoride (SF
6) electrical equipment obtained widely using, and specifically comprises SF
6Isolating switch, GIS switchgear, SF
6Transformer, voltage transformer (VT), current transformer and all kinds of bushings etc. of insulation.And at present in building electric pressure 110kv and above project, all use SF basically
6Switchgear.These electrical equipments play important effect in electric system, its reliability of operation not only is related to SF
6Electrical equipment itself, and influence other equipment, even the safety of whole electrical network.
Be in operation SF
6After gas is subjected to arc discharge or high temperature, can resolve into fluorine, sulphur and the fluorine sulphur compound of monomer, electric arc can be combined to stable SF again after disappearing
6Gas.But when containing moisture in the gas, the fluorine sulphur compound can generate the very strong chemical substance of corrosivity very strong hydrofluorite, sulfuric acid and other toxicity etc. with the water reaction, thereby the corrosion electrical equipment reduces apparatus insulated ability, jeopardizes maintainer's life security.To remove SF in the instrument fully
6The moisture of gas is impossible, but grasps SF constantly
6The gas micro-water content is taked corresponding prevention and control measure, reduces SF
6Moisture in the gas can guarantee and improve the safe operation reliability of isolating switch.Except micro-water content in the electric system high-tension switch cabinet, it also is indispensable that the aqueous vapor bulk concentration in the transformer oil detects.
Utilize the infrared spectrum absorption techniques that moisture in the SF6 isolating switch is detected, its advantage is that reaction velocity is fast, and is highly sensitive, and can realize online detection.But because optical device such as laser instrument, coupling mechanism, collimating apparatus, optical fiber is subjected to temperature easily, the influence of ambient stress factors vary and change light generation power and coupling efficiency, make by the transmission light light intensity behind the air chamber and change, thereby obscure with the light intensity variation that the gas absorption loss brings, bring measuring error.Measuring accuracy and the long-time stability of infrared spectrum absorption techniques have been influenced.
Mention temperature to the influence of light collimating apparatus in the paper " the angular deflection impact analysis of temperature on fiber collimating apparatus " [prompt photon journal the 35th volume 1509-1512 page or leaf in October, 2006 the 10th phase of Sun Ming]; Mention the influence of temperature on fiber coupling mechanism in the paper " temperature Response of Fused Optic Fiber Coupler " [Li Chuan, Zhang Yimo, Liu Tiegen, fourth victory sensing technology journal the 14th volume 196-198 page or leaf in the 3rd September calendar year 2001 phase].
Summary of the invention
For overcoming the deficiencies in the prior art and defective, the utility model proposes a kind of infrared gas detection system.
The technical solution of the utility model realizes in the following manner:
A kind of infrared gas detection system comprises temperature control circuit, current driving circuit, Distributed Feedback Laser, air chamber, photodetector, reference circuit, amplifying circuit, digital regulation resistance, difference channel, filtering circuit and microprocessor; It is characterized in that Distributed Feedback Laser is positioned at before the air chamber, the input end of another termination photodetector of air chamber, the output terminal of photodetector is connected with amplifying circuit, the output terminal of amplifying circuit and the output terminal of reference circuit are connected respectively to the input end of difference channel, the output terminal of difference channel connects the input end of filtering circuit, the output terminal of filtering circuit connects microprocessor, temperature control circuit is connected to Distributed Feedback Laser, current driving circuit connects microprocessor on one side, another side connects Distributed Feedback Laser, the driving signal of current driving circuit is sent by microprocessor, utilizes temperature control circuit and current driving circuit that Distributed Feedback Laser is carried out current drives and temperature-driven; The input end of digital regulation resistance connects microprocessor, the output terminal of digital regulation resistance is connected to the negative feedback gain control end of amplifying circuit, change the negative feedback gain of amplifying circuit by the resistance value of the dynamic regulating and controlling digital regulation resistance of microprocessor, thereby control the enlargement factor of amplifying circuit;
Described temperature control circuit by the integrated thermistor that is arranged on Distributed Feedback Laser inside and electric bridge that outer meeting resistance is formed, voltage ratio, temperature control chip and metal-oxide-semiconductor circuit form, wherein electric bridge is connected to the input end of voltage comparator, the output terminal of voltage comparator is connected to the temperature control chip, the temperature control chip is connected with the metal-oxide-semiconductor circuit, and the output terminal of metal-oxide-semiconductor circuit is connected with semiconductor cooler (Tec) on being encapsulated in Distributed Feedback Laser;
Described amplifying circuit is integrated double operational chip OPA2604;
Described current driving circuit is formed by connecting by DA and the integrated transporting discharging LM358 chip of microprocessor;
Described reference circuit is formed by connecting by DA and the integrated double operational chip OPA2604 of microprocessor.
Described photodetector is the PIN photodetector.
Described difference channel is precision instrument amplifier 8221 chips.
Described filtering circuit is universal active filter chip UAF42, is the low-pass filter structure.
Described microprocessor is the LPC1758 chip.
Described Distributed Feedback Laser is WSLS-137010C1424-20 butterfly type encapsulation (Distributed Feedback Laser) distributed feedback laser, and wavelength is 1370 ± 2nm.
Described digital regulation resistance is the max5388 that maxin produces, 256, and 50K Europe range digital regulation resistance.
Utilize said detecting system that air chamber is carried out the process that aqueous vapor detects, step is as follows:
1) detection system is connected; Connect the power supply of each circuit module and single-chip microcomputer, debugging light path and circuit make its operate as normal; Gas to be measured pours air chamber;
2) bridge resistor in the temperature control circuit is set at after the fixed value constant to realize the thermostatic control to Distributed Feedback Laser: utilize microprocessor to be created in that electric current changes 48mA in the 0.03S, change procedure is warmed up to 72mA from low to high from 24mA, and then back and forth carry out to 24mA from high to low from 72mA, the electric current variation range of setting is to be that the form of triangular wave realizes with output voltage corresponding in microprocessor; Because the Distributed Feedback Laser drive current variations can cause the variation of the output wavelength of Distributed Feedback Laser, the change in voltage output that arranges in microprocessor makes the output wavelength of Distributed Feedback Laser change, it is that 24mA makes the output wavelength of Distributed Feedback Laser change to the variation of the electric current between the 72mA that the variation range of output wavelength comprises, and the variation range of output wavelength has comprised the wavelength of water vapor absorption peak 1368.597nm;
3) regulate the amplifying circuit of transmission optical circuit and the enlargement factor of difference channel, observe its output signal with oscillograph during adjustment, making the amplitude of output voltage outside absorption peak is that 0mv is in the 100mv scope, at the voltage at absorption peak place below 3V, to satisfy the signal amplitude requirement that microprocessor is gathered;
4) after enlargement factor is adjusted, gathered out the signal that after water vapor absorption, produces with no absorption place at wavelength 1368.597nm place by microprocessor through filtering circuit, calculate the difference of these two signals and store this difference through microprocessor, above-mentioned collection, calculating and storing process repeat 1000 times, and the difference that simulates with microwater device after averaging and the relation of moisture content are that available microprocessor calculates aqueous vapor concentration;
5) gas to be measured detects and finishes powered-down.
The final absorption peak waveform that system of the present utility model detects is to subtract each other the back by the two-way triangular signal by difference channel to obtain, one the tunnel is the electric signal that light signal is converted to after by photodetector, another road is the analog electrical signal that reference circuit produces, final absorption peak waveform after Fig. 1 the first half is represented to subtract each other under the normal condition, A, the B point is does not have the wavelength location that absorbs, should be on same horizontal line, when environmental factor (as temperature, when stress) changing, signal light intensity by air chamber can take place to strengthen or decay, the road triangular wave (light signal conversion a road) that namely enters difference channel can increase or reduce, (pure electric signal is affected by environment very little and the simulation triangular wave electric signal that reference circuit produces is constant all the time, variation can be ignored), this has just caused final absorption peak waveform to distort, when strengthening as light intensity, be equivalent to be subtracted to such an extent that triangular wave increases, the final waveform signal that microprocessor collects can be the lower part waveform by the top wave form varies of Fig. 1, waveform generation distortion can make the microprocessor calculated difference change, thereby bring measuring error to measuring system, in order to address this problem, adopt based on the influence of digital regulation resistance real-Time Compensation environmental factor variation to detection system.
A kind ofly improve the method for infrared gas detection system stability based on digital regulation resistance, step is as follows:
1), the input end of digital regulation resistance is connected to microprocessor, the output terminal of digital regulation resistance is connected to the negative feedback gain control end of amplifying circuit, utilize microprocessor real time altering digital regulation resistance resistance to change the enlargement factor of amplifying circuit, oppositely compensating for variations intensity variations in proportion by the amplifying circuit enlargement factor makes that road triangular signal in the amplifying circuit input difference circuit remains unchanged;
2) two-way triangular wave electric signal, comprise that one the tunnel is the simulation triangular wave electric signal that reference circuit produces, the triangular signal that amplify by amplifying circuit for transmission light opto-electronic conversion on another road, the absorption peak waveform that obtains after the process difference channel difference is the final waveform of gathering of microprocessor, system works is when normal condition, when namely not having the change of environment factor, both sides, gas absorption peak should (both sides, gas absorption peak corresponding wavelength be all in the characteristic absorption zone at same horizontal level in the final collection waveform, no attenuation by absorption), when environmental factor changes, transmission light light intensity changes, the triangular wave that this road enters difference channel changes, wave form distortion, both sides, gas absorption peak misplace in the horizontal direction; In microprocessor chip, judge;
3) when the environmental factor change, during transmission light light intensity decreasing, increase the digital regulation resistance resistance by microprocessor, the amplifying circuit enlargement factor is increased, with the decay of the method compensation light intensity that oppositely increases the circuit enlargement factor in proportion, after same horizontal level is got back in both sides, gas absorption peak, illustrate that the triangular wave amplitude of light signal conversion in the difference channel returns to the size that environmental factor changes preceding triangular wave, the digital regulation resistance resistance no longer changes, and adjustment stops;
4) when the environmental factor change, when transmission light light intensity strengthens, reduce the digital regulation resistance resistance by microprocessor, the amplifying circuit enlargement factor is reduced, with the enhancing of the method compensation light intensity that oppositely reduces the circuit enlargement factor in proportion, make both sides, gas absorption peak get back to same horizontal level after, illustrate that the triangular wave amplitude of light signal conversion in the difference channel returns to the size that environmental factor changes preceding triangular wave, the digital regulation resistance resistance no longer changes, and adjustment stops;
5) above-mentioned adjustment was carried out once in 1 minute, can eliminate environmental factor in real time and change systematic influence, improved system stability.
The utlity model has following advantage: the utility model is convenient to be installed, simple in structure.By the real-time feedback regulation of the digital regulation resistance of control amplifier enlargement factor, eliminated the unsettled influence of environmental change and light source, the environment bigger in the temperature difference also can move, degree of accuracy and highly sensitive, and the response time is short, can in time monitor vapour concentration, easy and simple to handle, pollution-free, as long as change wavelength coverage, this way can be applied in the detection of other kind gas concentrations and go simultaneously, uses very extensive.
Description of drawings
Fig. 1 is for before and after environmental factor changes, and microprocessor collects the variation diagram of waveform, the waveform when top is divided into system's operate as normal, the distorted waveform the when bottom is divided into environmental factor and changes.
Fig. 2 is the structural representation of the utility model system.
Wherein: 1, current driving circuit, 2, temperature control circuit, 3, Distributed Feedback Laser, 4, air chamber, 5, photodetector, 6, amplifying circuit, 7, difference channel, 8, reference circuit, 9, filtering circuit, 10, microprocessor, 11, digital regulation resistance.
Fig. 3 is the digital regulation resistance circuit.CS is sheet choosing end, and CLK is spi bus clock end, and DIN is value input.Be connected to the corresponding GPIO pin of microprocessor or spi bus pin, by microprocessor control figure potentiometer resistance.W, L are that digital regulation resistance resistance output terminal is connected to amplifying circuit W shown in Figure 4, and the L two ends are as gain resistor.The power supply of 5V power supply all adds 104 electric capacity with the ground connection place and carries out filtering.
Fig. 4 is the amplifying circuit circuit diagram, adopt integrated double operational 2604 to amplify chip and finish the two-stage amplification, the negative pole of photodetector D4 is connected with current-limiting resistance R38, the positive pole of D4 is connected to the negative input end of first order amplifier, the output terminal of first order amplifier connects feedback resistance R39 as the gain controlling resistance, the other end of feedback resistance R39 is connected to the negative input end of first order amplifier, the positive input terminal ground connection of first order amplifier, first order amplifier out joins by the negative input end of resistance R 40 with second level amplifier, the positive input terminal of second level amplifier is by 1K resistance R 42 ground connection, the negative input end of second level amplifier and output terminal respectively with the resistance output terminal W of digital regulation resistance shown in Figure 3, the L end is connected, and the output terminal of second level amplifier connects the negative input end (being on the Rg resistance) of difference channel shown in Figure 5; 4,8 pin of amplifying circuit connect negative, positive 12V power supply respectively, and negative, positive 12V power supply and ground connection are connected capacitor C 35 respectively between the place, C33 carries out filtering.
Fig. 5 is difference channel and filtering circuit circuit diagram, difference channel adopts amplifier 8221 chips, its negative input end connects resistance R g, positive input terminal connects resistance R h, 3 pin of 8221 chips connect intermediate ends and the end of potentiometer R, the other end of potentiometer R connects 2 pin of 8221 chips, and potentiometer R can be to the difference channel control that gains; 5,8 pin of 8221 chips connect negative, positive 12V power supply respectively, and negative, positive 12V power supply and ground connection are connected capacitor C 41 respectively between the place, C40 carries out filtering; Output terminal 7 pin of 8221 chips connect resistance R m, and the other end of Rm connects resistance R n ground connection afterwards, and the common port of Rm and Rn is connected to filtering circuit; Filtering circuit is the low-pass filter that active power filtering chip UAF constitutes, wherein resistance R i is connected 8 pin and 16 pin of filtering chip UAF, resistance R k is connected to 9 pin and 14 pin of filtering chip UAF, the A/D end that its 1 pin connects microprocessor carries out data acquisition, 2 pin, 15 pin ground connection, 10 pin, 11 pin connect negative, positive 12V power supply respectively, and negative, positive 12V power supply and ground connection are connected capacitor C 43 respectively between the place, C42 carries out filtering; In the low-pass filter by Ri, Rk, Rm, the resistance of Rn decides the filtering cutoff frequency.
Embodiment
Below in conjunction with drawings and Examples the utility model is described further, but is not limited thereto.
Embodiment:
The utility model embodiment is as shown in Figure 2: a kind of infrared gas detection system, comprise current driving circuit 1, temperature control circuit 2, Distributed Feedback Laser 3, air chamber 4, photodetector 5, amplifying circuit 6, difference channel 7, reference circuit 8, filtering circuit 9, microprocessor 10, digital regulation resistance 11, it is characterized in that Distributed Feedback Laser 3 is positioned at before the air chamber 4, the input end of air chamber 4 another termination photodetectors 5, the output terminal of photodetector 5 is connected with amplifying circuit 6
The output terminal of the output terminal of amplifying circuit 6 and reference circuit 8 is connected respectively to the input end of difference channel 7, the output terminal of difference channel 7 connects the input end of filtering circuit 9, the output terminal of filtering circuit 9 connects microprocessor 10, temperature control circuit 2 is connected to Distributed Feedback Laser 3, current driving circuit 1 connects microprocessor 10 on one side, another side connects Distributed Feedback Laser 3, the driving signal of current driving circuit 1 is sent by microprocessor 10, utilizes temperature control circuit 2 and 1 pair of Distributed Feedback Laser of current driving circuit 3 to carry out current drives and temperature-driven; The input end of digital regulation resistance 11 connects microprocessor 10, the output terminal of digital regulation resistance 11 is connected to the negative feedback gain control end of amplifying circuit 6, change the negative feedback gain of amplifying circuit 6 by the resistance value of microprocessor 10 dynamic regulating and controlling digital regulation resistances 11, thereby control the enlargement factor of amplifying circuit 6;
The electric bridge that described temperature control circuit 2 is made up of the integrated thermistor that is arranged on Distributed Feedback Laser 3 inside and outer meeting resistance, voltage ratio are, temperature control chip and metal-oxide-semiconductor circuit form, wherein electric bridge is connected to the input end of voltage comparator, the output terminal of voltage comparator is connected to the temperature control chip, the temperature control chip is connected with the metal-oxide-semiconductor circuit, and the output terminal of metal-oxide-semiconductor circuit is connected with semiconductor cooler (Tec) on being encapsulated in laser instrument;
Described amplifying circuit 6 is integrated double operational chip OPA2604;
Described current driving circuit 1 is formed by connecting by DA and the integrated transporting discharging LM358 chip of microprocessor;
Described reference circuit 8 is formed by connecting by DA and the integrated double operational chip OPA2604 of microprocessor.
Described photodetector 5 is PIN photodetectors.
Described difference channel 7 is precision instrument amplifier 8221 chips.
Described filtering circuit 9 is universal active filter chip UAF42, is the low-pass filter structure.
Described microprocessor 10 is the LPC1758 chip.
Described Distributed Feedback Laser 3 is WSLS-137010C1424-20 butterfly type encapsulation (Distributed Feedback Laser) distributed feedback lasers, and wavelength is 1370 ± 2nm.
The max5388 that described digital regulation resistance 11 is produced for maxin, 256,50K Europe range digital regulation resistance.
Claims (2)
1. an infrared gas detection system comprises temperature control circuit, current driving circuit, Distributed Feedback Laser, air chamber, photodetector, reference circuit, amplifying circuit, digital regulation resistance, difference channel, filtering circuit and microprocessor; It is characterized in that Distributed Feedback Laser is positioned at before the air chamber, the input end of another termination photodetector of air chamber, the output terminal of photodetector is connected with amplifying circuit, the output terminal of amplifying circuit and the output terminal of reference circuit are connected respectively to the input end of difference channel, the output terminal of difference channel connects the input end of filtering circuit, the output terminal of filtering circuit connects microprocessor, temperature control circuit is connected to Distributed Feedback Laser, current driving circuit connects microprocessor on one side, another side connects Distributed Feedback Laser, the driving signal of current driving circuit is sent by microprocessor, utilizes temperature control circuit and current driving circuit that Distributed Feedback Laser is carried out current drives and temperature-driven; The input end of digital regulation resistance connects microprocessor, the output terminal of digital regulation resistance is connected to the negative feedback gain control end of amplifying circuit, change the negative feedback gain of amplifying circuit by the resistance value of the dynamic regulating and controlling digital regulation resistance of microprocessor, thereby control the enlargement factor of amplifying circuit;
Described temperature control circuit by the integrated thermistor that is arranged on Distributed Feedback Laser inside and electric bridge that outer meeting resistance is formed, voltage ratio, temperature control chip and metal-oxide-semiconductor circuit form, wherein electric bridge is connected to the input end of voltage comparator, the output terminal of voltage comparator is connected to the temperature control chip, the temperature control chip is connected with the metal-oxide-semiconductor circuit, and the output terminal of metal-oxide-semiconductor circuit is connected with semiconductor cooler on being encapsulated in Distributed Feedback Laser;
Described amplifying circuit is integrated double operational chip OPA2604;
Described current driving circuit is formed by connecting by DA and the integrated transporting discharging LM358 chip of microprocessor;
Described reference circuit is formed by connecting by DA and the integrated double operational chip OPA2604 of microprocessor.
2. a kind of infrared gas detection system as claimed in claim 1 is characterized in that described photodetector is the PIN photodetector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320093237 CN203148842U (en) | 2013-02-28 | 2013-02-28 | Infrared gas detecting system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320093237 CN203148842U (en) | 2013-02-28 | 2013-02-28 | Infrared gas detecting system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203148842U true CN203148842U (en) | 2013-08-21 |
Family
ID=48976358
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201320093237 Withdrawn - After Issue CN203148842U (en) | 2013-02-28 | 2013-02-28 | Infrared gas detecting system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203148842U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103149172A (en) * | 2013-02-28 | 2013-06-12 | 山东大学 | Method for improving stability of infrared gas detection system based on digital potentiometer |
| CN106525131A (en) * | 2016-11-24 | 2017-03-22 | 安徽庆宇光电科技有限公司 | Road side breathing zone air quality online monitoring system |
| CN113324651A (en) * | 2021-05-13 | 2021-08-31 | 浙江威星智能仪表股份有限公司 | Photoelectric signal sampling circuit based on digital resistor and configuration method thereof |
-
2013
- 2013-02-28 CN CN 201320093237 patent/CN203148842U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103149172A (en) * | 2013-02-28 | 2013-06-12 | 山东大学 | Method for improving stability of infrared gas detection system based on digital potentiometer |
| CN103149172B (en) * | 2013-02-28 | 2015-03-04 | 山东大学 | Method for improving stability of infrared gas detection system based on digital potentiometer |
| CN106525131A (en) * | 2016-11-24 | 2017-03-22 | 安徽庆宇光电科技有限公司 | Road side breathing zone air quality online monitoring system |
| CN113324651A (en) * | 2021-05-13 | 2021-08-31 | 浙江威星智能仪表股份有限公司 | Photoelectric signal sampling circuit based on digital resistor and configuration method thereof |
| CN113324651B (en) * | 2021-05-13 | 2024-03-15 | 浙江威星智能仪表股份有限公司 | Photoelectric signal sampling circuit based on digital resistor and configuration method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103149172B (en) | Method for improving stability of infrared gas detection system based on digital potentiometer | |
| CN203148842U (en) | Infrared gas detecting system | |
| CN205139006U (en) | Dew point measurement device based on laser spectrum absorbs detection | |
| CN103017991B (en) | Suction type SF6 gas leakage monitoring method | |
| CN106338475A (en) | SF6 gas component online real-time monitoring apparatus and SF6 gas component online real-time monitoring method | |
| CN103439232A (en) | Obscuration type soot particle concentration measuring method and device thereof | |
| CN102495021B (en) | System and method for detecting trace amount of steam based on two absorption peaks | |
| CN205262956U (en) | Infrared SF6 sensor device of relevant NDIR | |
| CN103528993A (en) | Laser gas analyzer | |
| CN102313603B (en) | All-fiber-pulse balanced homodyne detection apparatus | |
| CN103364365A (en) | WSN (Wireless Sensor Network) sensor node for natural gas content in air | |
| CN103472003A (en) | Novel method used for phase lock voltage subtraction of micro water vapor detection | |
| CN105241837B (en) | A kind of infrared gas detection system that can improve detection stability | |
| CN107389560A (en) | Multiband all -fiber high spectral resolution total atmospheric spectral transmittance simultaneous measuring apparatus and measuring method | |
| CN206858674U (en) | A kind of aluminium electrolysis anode guide rod distributed current Detection ＆ Controling apparatus and system | |
| CN204389583U (en) | A kind of grounding net of transformer substation three-dimensional digital monitoring data collector | |
| CN205157423U (en) | Can improve infrared gaseous detecting system who detects stability | |
| CN205262957U (en) | Gas concentration detection system based on programmable amplifier | |
| CN107727899A (en) | A kind of direct current energy meter | |
| CN202916062U (en) | Suction-type SF6 gas leakage monitoring device | |
| CN110160628A (en) | A kind of demodulating system and method for optical fiber raster vibration signal | |
| CN202631420U (en) | Photoelectric detection circuit of heavy metal online monitor | |
| CN112261148A (en) | Subway construction monitoring signal transmission system based on Internet of things | |
| CN105241836A (en) | System and method for gas concentration detection based on programmable amplifier | |
| CN103411902A (en) | Wide-range micro-water measuring system based on programmable amplifier |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20130821 Effective date of abandoning: 20150304 |
|
| AV01 | Patent right actively abandoned |
Granted publication date: 20130821 Effective date of abandoning: 20150304 |
|
| RGAV | Abandon patent right to avoid regrant |