CN204008440U - The signal processing apparatus and the gas detecting system thereof that detect for difference gas - Google Patents
The signal processing apparatus and the gas detecting system thereof that detect for difference gas Download PDFInfo
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- CN204008440U CN204008440U CN201420192551.8U CN201420192551U CN204008440U CN 204008440 U CN204008440 U CN 204008440U CN 201420192551 U CN201420192551 U CN 201420192551U CN 204008440 U CN204008440 U CN 204008440U
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Abstract
The utility model relates to a kind of signal processing apparatus detecting for difference gas, and described signal processing apparatus comprises the pretreatment unit, arithmetic element and the post-processing unit that connect successively; Described pretreatment unit receives described different electric signal, obtains its difference and this difference is converted to digital signal by simulating signal; Described arithmetic element multiplies each other digital signal and the reference signal of described pretreatment unit output obtain its DC component; The DC component that described post-processing unit is obtained described arithmetic element is optimized, compensates and change and obtains specifying in gas to be measured the concentration of composition.The utility model is also established and a kind of gas detecting system that uses said signal processing device.Implement signal processing apparatus and the gas detecting system thereof detecting for difference gas of the present utility model, there is following beneficial effect: conversion speed is very fast, system overhead is less, cost is low, realization is easy.
Description
Technical field
The utility model relates to gas and detects, and more particularly, relates to a kind of signal processing apparatus and gas detecting system thereof detecting for difference gas.
Background technology
Along with becoming increasingly conspicuous of environmental problem, monitored gas environment technology has become the important topic of each research institution, environmental administration.NO
2as one of Pollution Gas, its detection technique research is mainly contained to galvanochemistry and two kinds of methods of spectroscopy.Wherein the electrochemical process response time is long, the life-span is short, precision is limited.Spectroscopic method is the ultraviolet-visible light difference absorption spectrum technology that adopt more, and broadband spectral is analyzed, and can detect multiple gases, but this method are subject to absorption spectrum eclipse effect, so should avoid the overlap action of gas absorption spectra to be measured while measurement.At present, it is that two kinds of gas absorption interfaces that impact that this method of ultraviolet-visible light difference absorption spectrum technology is subject to spectra overlapping detects simultaneously have when overlapping and can overlap the absorption of light that NO2 detects main method, causes measuring error.On the other hand, it is to use modulated light to pass through gas with various that difference gas detects, one of them is gas to be detected, another is reference gas (normally normal, dry air), due to the composition difference in these two kinds of gases, therefore, light is different through the light intensity after these two kinds of gases, to be converted to electric signal through the light signal after gas, and obtain its difference, obtain specifying in gas to be measured the concentration of composition by a series of processing to this difference signal, for example, NO
2.So in this difference gas detects, the signal processing unit of differential signal is very important.In the prior art, in order to ensure measurement result, conventionally realize above-mentioned signal processing with software.But, use the method for software need to use the processor that function is comparatively powerful, it is difficult for realizing, and cost is high.
Utility model content
The technical problems to be solved in the utility model is, for the high defect of above-mentioned difficult realization, the cost of prior art, provides a kind of and easily realizes, lower-cost signal processing apparatus and the gas detecting system thereof detecting for difference gas.
The utility model solves the technical scheme that its technical matters adopts: construct a kind of signal processing apparatus detecting for difference gas, described difference gas detects and carries out light splitting by the modulated light that light source is sent, make modulated light after light splitting respectively by the reference gas chamber of gas with various being housed and detecting air chamber, thereby obtain different electric signal, make described different electric signal process by signal processing apparatus and to it concentration that obtains specifying in gas to be measured composition, described signal processing apparatus comprises the pretreatment unit connecting successively, arithmetic element and post-processing unit, described pretreatment unit receives described different electric signal, obtains its difference and this difference is converted to digital signal by simulating signal, described arithmetic element multiplies each other digital signal and the reference signal of described pretreatment unit output obtain its DC component, the DC component that described post-processing unit is obtained described arithmetic element is optimized, compensates and change and obtains specifying in gas to be measured the concentration of composition.
Further, described pretreatment unit comprises the differential amplifier, bandpass filter and the analog to digital converter that connect successively; Two input ends of described differential amplifier are connected to and will be converted to the output terminal of the sensor of electric signal through the light of described reference gas chamber and detection air chamber, the differential signal transmission of its output terminal is to the input end of described bandpass filter, and the output terminal of described bandpass filter is connected with the input end of described analog to digital converter.
Further, described arithmetic element comprises the multiplier and the low-pass filter that connect successively; An input end of described multiplier is connected with the input end of described analog to digital converter, its another input end input reference signal; The output terminal of described multiplier is connected with the input end of described low-pass filter, and described low-pass filter outputs to described post-processing unit after obtaining the DC component of input signal.
Further, described reference signal is to obtain through phase shift for the modulation signal of modulated light source.
Further, the phase shifter that described phase shift is made up of RC phase-shift circuit is realized, and described phase shifter is by the modulation signal phase shift for modulated light source and be input to another input end of described multiplier; Described phase shifter carries out the phase adjusted of its scope between-90 to 90 degree, and making the difference of the phase place of two input end input signals of described multiplier is 90 degree.
Further, described post-processing unit comprises the gain amplifier, data-optimized unit and the display unit that connect successively; Described gain amplifier amplifies the DC component of described low-pass filter output, makes it be suitable for follow-up processing; Described data-optimized unit is adjusted and is changed the signal of described gain amplifier output; The result that described display unit is that described data-optimized unit obtains for showing, expression detects air chamber gas appointment constituent concentration.
Further, the signal processing apparatus that described difference gas detects is for detection of the concentration of nitrogen dioxide in air, and its display unit detects the concentration of air demonstration nitrogen dioxide in air chamber.
Further, in described reference gas chamber, be the air that is dried, does not contain nitrogen dioxide as sample; It in described detection air chamber, is the air to be detected of obtaining in test site.
The utility model also relates to a kind of difference gas detecting system, this system is carried out light splitting by the modulated light that light source is sent, make modulated light after light splitting respectively by the reference gas chamber of gas with various being housed and detecting air chamber, thereby obtain different electric signal, make described different electric signal process by signal processing apparatus and to it concentration that obtains specifying in gas to be measured composition, described first signal reason device is the signal processing apparatus described in above-mentioned any one.
Implement signal processing apparatus and the gas detecting system thereof detecting for difference gas of the present utility model, there is following beneficial effect: owing to using and all being formed by hardware in difference gas detects, comparatively simple signal processing apparatus, the calculus of differences of its two paths of signals is realized by differential amplifier, and realize the signal processing function of realizing by software in prior art, in the signal processing apparatus of having avoided detecting at difference gas, use microprocessor, thereby make the conversion speed of this difference gas detecting system very fast, system overhead is less, cost is low, realize easily.
Brief description of the drawings
Fig. 1 is that the utility model is for the signal processing apparatus of difference gas detection and the structural representation of this signal processing apparatus of gas detecting system embodiment thereof;
Fig. 2 is the structural representation of post-processing unit in described embodiment.
Embodiment
Below in conjunction with accompanying drawing, the utility model embodiment is described further.
As shown in Figure 1, the signal processing apparatus and the gas detecting system embodiment thereof that detect for difference gas at the utility model, this signal processing apparatus is a part for gas detecting system, the gas detecting system that this use difference gas detects carries out light splitting by the modulated light that light source is sent, make modulated light after light splitting respectively by the reference gas chamber of gas with various being housed and detecting air chamber, thereby obtain different electric signal, make the different electric signal obtaining process by this signal processing apparatus and to it concentration (concentration of certain objectionable impurities normally containing in Test Field gas) that obtains specifying in gas to be measured composition.In Fig. 1, except light source, signal source, optical splitter, reference gas chamber, detection air chamber and two photoelectric commutators, remaining part is exactly signal processing apparatus related in the present embodiment, it is for the treatment of the electric signal obtaining by different air chambers, and by wherein obtaining the concentration of designated substance in gas.At the present embodiment, signal processing apparatus comprises the pretreatment unit 1, arithmetic element 2 and the post-processing unit 3 that connect successively; Wherein, pretreatment unit 1 receives above-mentioned two different electric signal that obtain by different air chambers respectively, obtains its difference and this difference is converted to digital signal by simulating signal; The digital signal that arithmetic element 2 is exported this pretreatment unit 1 and reference signal multiply each other and obtain its DC component; The DC component that post-processing unit 3 is obtained this arithmetic element 2 is optimized, compensates and change and obtains specifying in gas to be measured the concentration of composition.
In the present embodiment, as shown in Figure 1, pretreatment unit 1 comprises again the differential amplifier 11, bandpass filter 12 and the analog to digital converter 13 that connect successively, wherein, two input ends of differential amplifier 11 are connected to through reference gas chamber with detect air chamber, modulated light is converted to the output terminal of the photoelectric sensor of electric signal, the differential signal transmission of its output terminal is to the input end of bandpass filter 12, the signal that bandpass filter 12 obtains it carries out filtering, then output to the input end of above-mentioned analog to digital converter 13, namely, the output terminal of bandpass filter 12 is connected with the input end of analog to digital converter 13, the simulating signal that analog to digital converter 13 is received is converted to digital signal, be transported to arithmetic element 2.Arithmetic element 2 comprises the multiplier 21 and the low-pass filter 22 that connect successively; Wherein, an input end of multiplier 21 is connected with the output terminal of analog to digital converter 13, receives the digital signal from analog to digital converter 13; Its another input end input reference signal, this reference signal be come from signal source, obtain by phase shift for the modulation signal of modulated light source; Refer to Fig. 1, between signal source and this input end of multiplier 21, be serially connected with a phase shifter, realize the phase shift to above-mentioned modulation signal; In the present embodiment, this phase shifter is a RC phase-shift circuit, can carry out-90 degree to 90 degree phase adjusted, and making the phase differential of the signal of its output and the input signal of multiplier 21 another input ends is 90 degree; In addition, in the present embodiment, the output terminal of multiplier 21 is connected with the input end of low-pass filter 22, and low-pass filter 22 outputs to post-processing unit 3 after obtaining the DC component of input signal.
In the present embodiment, post-processing unit 3 comprises the gain amplifier 31, data-optimized unit 32 and the display unit 33 that connect successively; The DC component that gain amplifier 31 is exported low-pass filter 22 is amplified, and makes it be suitable for follow-up processing; The signal that data-optimized unit 32 is exported gain amplifier 31 is adjusted and is changed; Display unit 33 is specified the result of constituent concentration for showing that data-optimized unit 32 is that obtain, represent to detect air chamber gas.In the present embodiment, above-mentioned display unit 33 can be LED or LCD display.
Refer to Fig. 2, the concrete structure of data-optimized unit 33 has in the present embodiment been shown in Fig. 2.In Fig. 2, data-optimized unit 33 comprises average treatment circuit, data scaling circuit, data compensating circuit, least square circuit and inverter circuit; The output signal of average treatment circuit receiving gain amplifier 31, obtains its mean value, and this mean value is outputed to data scaling circuit and data compensating circuit; Data compensating circuit arrives data scaling circuit according to the mean value output compensation rate of input; Signal amplitude or intensity after data scaling circuit is compensated according to the mean value of inputting and compensation rate also outputs to least square circuit; And least square circuit carries out matching to data Calibration Circuit output signal, and result is outputed to inverter circuit; The signal of inverter circuit after to matching carries out inverting, obtains specifying the concentration of composition.
At the present embodiment, the signal processing apparatus that difference gas detects is for detection of the concentration of nitrogen dioxide in air, and its display unit detects the concentration of air demonstration nitrogen dioxide in air chamber.And in its reference gas chamber, be the air that is dried, does not contain nitrogen dioxide as sample; Detecting in air chamber is the air to be detected of obtaining in test site.
In the present embodiment, also relate to a kind of difference gas detecting system, this system is carried out light splitting by the modulated light that light source is sent, make modulated light after light splitting respectively by the reference gas chamber of gas with various being housed and detecting air chamber, thereby obtain different electric signal, make described different electric signal process by signal processing apparatus and to it concentration that obtains specifying in gas to be measured composition, described first signal reason device is above-mentioned signal processing apparatus.
In the present embodiment, overall on, signal source, mainly for generation of modulation signal and the reference signal of light source, mainly utilizes frequency divider to realize the adjustment of signal frequency, can carry out to light source the modulation of the waveform different frequencies such as sine wave, square wave, square wave; Optical splitter is for being divided into two-way light respectively by concentration NO to be measured is housed by the light source after modulation
2the detection air chamber of gas and the reference gas chamber that dry air is housed, the light beam that detects air chamber is received by photoelectric commutator 1, and the light beam of reference gas chamber is received by photoelectric commutator 2; Two photoelectric commutators convert the light signal of reception to electric signal, pretreatment unit is mainly by differential amplifier, bandpass filter, phase-shifter and A/D converting unit composition, differential amplifier Output rusults access bandpass filter is carried out filtering processing, and result is carried out to A/D conversion, wait for follow-up computing; In addition, the effect of phase-shifter is to adjust reference signal phase place, ensures that it synchronizes with measuring-signal, so that follow-up computing.
Arithmetic element is mainly used in digital signal and reference signal after A/D conversion to carry out computing cross-correlation, comprises multiplier and low-pass filter two parts.Due to reference signal after phase shift and measuring-signal frequency, homophase together, multiplication result comprises high-frequency signal and direct current signal, and the effect of low-pass filter is the direct current signal that high-frequency signal filtering is obtained carrying concentration information, so that subsequent calculations gas concentration.
Post-processing unit is mainly used in carrying out calculating and the demonstration of gas concentration, comprises gain amplifier, data-optimized unit and display unit.The direct current signal of low-pass filter output is carried out corresponding gain amplification by gain amplifier, is then linked into operations such as optimizing unit averages, compensation data, demarcation, least square fitting, inverting, finally the gas concentration obtaining shown.
Owing to adopting double light path differential configuration, will measure air chamber signal and reference gas cell signal difference processing, can weaken the impact that light source fluctuation brings, also can eliminate to a certain extent circuit and ground unrest, be conducive to improve system sensitivity.Meanwhile, can show in real time, online in the present embodiment NO
2the concentration change of gas, fast response time, data processing operation facilitate, precision is high; Meanwhile, for system cost, owing to adopting hardware to realize major function, cost is lower, performance is also better.
In the present embodiment, its detection principle is: in the time that characteristic frequency light wave passes through gas, can occur interact and light intensity is changed with gas, its interactively meets gas absorption law Lambert-Beer's law:
I
t(λ)＝I
0(λ)exp[-σ(λ)CL]
Wherein, I
0(λ) be initial incident intensity; σ (λ) is absorption cross section coefficient; C is tested gas concentration; L gas absorption light path; I
t(λ) be transmitted intensity.σ (λ) is the base attribute of gas, relevant with temperature and pressure.Under normal circumstances, σ (λ) CL is far smaller than 1, therefore can obtain following expression:
I
t(λ)≈I
0(λ)[1-σ(λ)CL]
After modulation, be:
Wherein k is the index of modulation, and from above formula, light source is through modulating and passing through after gas, and in output signal, modulation signal part carries gas concentration information, therefore, as long as the amplitude of measuring modulation signal by correlation detection technology just can record the concentration of gas.
In the present embodiment, the course of work of gas detecting system is: signal source produces the modulation signal of required frequency to the corresponding modulation of light source, after light splitting, two-beam is respectively by detecting air chamber and reference gas chamber, the light signal receiving is converted to electric signal by photoelectric commutator 1 and photoelectric commutator 2, two input ends of access differential amplifier respectively, the signal of difference processing is converted to digital signal by A/D change-over circuit by simulating signal after bandpass filtering, and an input end of access multiplier is waited for follow-up computing; Simultaneously, source produces that the reference signal of synchronizeing with modulation signal accesses multiplier after phase-shifter adjustment and measured signal carries out multiplying, multiplication output signal obtains carrying the direct current signal of gas concentration information after low-pass filter, direct current signal access post-processing unit amplifies through gain, average with data-optimized unit, obtain gas concentration measurement value after the sequence of operations such as compensation data, demarcation, least square fitting, inverting, finally show.Owing to can extract in the present embodiment faint useful (the carrying gas concentration information) signal needing from noise.Can realize in real time like this, show online NO
2gas concentration, has simplified detection system design, is convenient to realize system miniaturization with intelligent, has further lowered system cost.
The above embodiment has only expressed several embodiment of the present utility model, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to the utility model the scope of the claims.It should be pointed out that for the person of ordinary skill of the art, without departing from the concept of the premise utility, can also make some distortion and improvement, these all belong to protection domain of the present utility model.Therefore, the protection domain of the utility model patent should be as the criterion with claims.
Claims (9)
1. the signal processing apparatus detecting for difference gas, described difference gas detects and carries out light splitting by the modulated light that light source is sent, make modulated light after light splitting respectively by the reference gas chamber of gas with various being housed and detecting air chamber, thereby obtain different electric signal, make described different electric signal process by signal processing apparatus and to it concentration that obtains specifying in gas to be measured composition, it is characterized in that, described signal processing apparatus comprises the pretreatment unit, arithmetic element and the post-processing unit that connect successively; Described pretreatment unit receives described different electric signal, obtains its difference and this difference is converted to digital signal by simulating signal; Described arithmetic element multiplies each other digital signal and the reference signal of described pretreatment unit output obtain its DC component; The DC component that described post-processing unit is obtained described arithmetic element is optimized, compensates and change and obtains specifying in gas to be measured the concentration of composition.
2. the signal processing apparatus detecting for difference gas according to claim 1, is characterized in that, described pretreatment unit comprises the differential amplifier, bandpass filter and the analog to digital converter that connect successively; Two input ends of described differential amplifier are connected to and will be converted to the output terminal of the sensor of electric signal through the light of described reference gas chamber and detection air chamber, the differential signal transmission of its output terminal is to the input end of described bandpass filter, and the output terminal of described bandpass filter is connected with the input end of described analog to digital converter.
3. the signal processing apparatus detecting for difference gas according to claim 2, is characterized in that, described arithmetic element comprises the multiplier and the low-pass filter that connect successively; An input end of described multiplier is connected with the input end of described analog to digital converter, its another input end input reference signal; The output terminal of described multiplier is connected with the input end of described low-pass filter, and described low-pass filter outputs to described post-processing unit after obtaining the DC component of input signal.
4. the signal processing apparatus detecting for difference gas according to claim 3, is characterized in that, described reference signal is to obtain through phase shift for the modulation signal of modulated light source.
5. the signal processing apparatus detecting for difference gas according to claim 4, it is characterized in that, the phase shifter that described phase shift is made up of RC phase-shift circuit is realized, and described phase shifter is by the modulation signal phase shift for modulated light source and be input to another input end of described multiplier; Described phase shifter carries out the phase adjusted of its scope between-90 to 90 degree, and making the difference of the phase place of two input end input signals of described multiplier is 90 degree.
6. the signal processing apparatus detecting for difference gas according to claim 5, is characterized in that, described post-processing unit comprises the gain amplifier, data-optimized unit and the display unit that connect successively; Described gain amplifier amplifies the DC component of described low-pass filter output, makes it be suitable for follow-up processing; Described data-optimized unit is adjusted and is changed the signal of described gain amplifier output; The result that described display unit is that described data-optimized unit obtains for showing, expression detects air chamber gas appointment constituent concentration.
7. the signal processing apparatus detecting for difference gas according to claim 6, it is characterized in that, the signal processing apparatus that described difference gas detects is for detection of the concentration of nitrogen dioxide in air, and its display unit detects the concentration of air demonstration nitrogen dioxide in air chamber.
8. the signal processing apparatus detecting for difference gas according to claim 7, is characterized in that, is the air that is dried, does not contain nitrogen dioxide as sample in described reference gas chamber; It in described detection air chamber, is the air to be detected of obtaining in test site.
9. a difference gas detecting system, this system is carried out light splitting by the modulated light that light source is sent, make modulated light after light splitting respectively by the reference gas chamber of gas with various being housed and detecting air chamber, thereby obtain different electric signal, make described different electric signal process by signal processing apparatus and to it concentration that obtains specifying in gas to be measured composition, it is characterized in that, described signal processing apparatus is the signal processing apparatus described in any one in claim 1-8.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105466491A (en) * | 2015-12-28 | 2016-04-06 | 中国科学院武汉物理与数学研究所 | Imaging-type combustion temperature and concentration measurement device based on dual-channel molecule optical filtering |
| CN107796784A (en) * | 2017-09-04 | 2018-03-13 | 国网山东省电力公司电力科学研究院 | SF6 Insulating A High-Voltages electrical equipment gas componant on-Line Monitor Device and monitoring method |
| CN110553987A (en) * | 2019-08-28 | 2019-12-10 | 华中科技大学 | gas detection method and system |
| CN110987869A (en) * | 2019-12-12 | 2020-04-10 | 华中科技大学 | Integrated optical fiber gas detection system and method |
| CN112629772A (en) * | 2020-12-10 | 2021-04-09 | 中铁七局集团电务工程有限公司 | Seal testing system for pneumatic tension compensator |
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2014
- 2014-04-18 CN CN201420192551.8U patent/CN204008440U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105466491A (en) * | 2015-12-28 | 2016-04-06 | 中国科学院武汉物理与数学研究所 | Imaging-type combustion temperature and concentration measurement device based on dual-channel molecule optical filtering |
| CN107796784A (en) * | 2017-09-04 | 2018-03-13 | 国网山东省电力公司电力科学研究院 | SF6 Insulating A High-Voltages electrical equipment gas componant on-Line Monitor Device and monitoring method |
| CN110553987A (en) * | 2019-08-28 | 2019-12-10 | 华中科技大学 | gas detection method and system |
| CN110987869A (en) * | 2019-12-12 | 2020-04-10 | 华中科技大学 | Integrated optical fiber gas detection system and method |
| CN112629772A (en) * | 2020-12-10 | 2021-04-09 | 中铁七局集团电务工程有限公司 | Seal testing system for pneumatic tension compensator |
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