CN203148839U - Standard signal source for simulating gas absorption condition in optical fiber sensing detection gas - Google Patents
Standard signal source for simulating gas absorption condition in optical fiber sensing detection gas Download PDFInfo
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- CN203148839U CN203148839U CN 201320122508 CN201320122508U CN203148839U CN 203148839 U CN203148839 U CN 203148839U CN 201320122508 CN201320122508 CN 201320122508 CN 201320122508 U CN201320122508 U CN 201320122508U CN 203148839 U CN203148839 U CN 203148839U
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Abstract
The utility model discloses a standard signal source for simulating gas absorption condition in an optical fiber sensing detection gas, and belongs to the technical field of signal sources in optical fiber sensing. The device comprises a wave form memory and an upper computer. A frequency word register is connected onto a phase accumulator for providing frequency words to the phase accumulator, the output of the phase accumulator is connected onto an address wire of the wave form memory, the wave form memory is connected onto a D/A (Digital/Analog) converter, a system clock frequency source is respectively connected with the phase accumulator and the D/A converter for providing identical fundamental frequency to the phase accumulator and the D/A converter, the D/A converter is connected with a low pass wave filter for adjusting a signal wave converted by the D/A converter through a filter circuit, and the upper computer is respectively connected onto the wave form memory and the frequency word register for writing wave form data into the wave form memory and writing the frequency words into the frequency word register. The standard signal source disclosed by the utility model is high in digital degree, convenient to integrate, small in volume, light in weight, stable in wave form, high in precision and capable of flexibly adjusting the amplitude and the frequency and providing high-quality standard signals to the optical fiber sensing detection gas.
Description
Technical field
The utility model relates to the standard signal source of gas absorption situation in a kind of analog optical fiber sensing detection gas, belongs to the signal source technical field in the Fibre Optical Sensor.
Background technology
At present, adopt Differential Absorption Optical Fiber gas to detect sensing technology gas is detected used system, its basic structure such as Fig. 1, earlier provide light signal by laser instrument 1, be divided into the aplanatic optically-coupled of two bundles through beam splitter 2 by 1:1 and enter optical fiber, one the tunnel through air chamber 3, and light is converted into the signal wave that has gas information through getting to after the gas absorption on the photodetector 4; Another road is directly got to becomes reference wave on the photodetector, next two paths of signals changes normalization circuits such as potential circuit, subtracter or divider and draws the gas absorption peak by filtering.
The above-mentioned gas detection system roughly can be two large divisions before and after boundary is divided into the photodetector, and first half mainly is light path, and latter half mainly is circuit.Obviously, many influence factors of first half can be brought many difficulties to the debugging of back analog module.Many times can because of opticator can't provide one comparatively standard signal wave and make the analog module debugging of back to carry out or seem meaningless.For example, the path length difference of double light path, the bending of optical fiber, stress difference, two photodetectors encapsulate water vapour content difference into, and these all can influence flashlight, also need in addition oneself to make the environment that air chamber comes analog gas to detect, air chamber is made trouble, the build heaviness, most importantly sealing problem brings inconvenience to R﹠D process.(application number is people's such as Chang Jun, Wang Zongliang, Wang Wei outstanding person, Song Fujun utility model patent " a kind of little water pick-up unit based on scanning method ": 201120074340.0) be exactly a kind of gas-detecting device that utilizes signal source scanning to obtain steam information, because the signal source of this device gets through a series of light paths such as air chambers by the Distributed Feedback Laser bright dipping, therefore be subjected to influence water-bed in Distributed Feedback Laser, collimating apparatus, the photodetector, the accuracy of gained signal source certainly will be affected with precision, directly influences the debugging of back circuit.And common signal generator can only produce fixed waveforms such as sine wave, triangular wave, square wave, sawtooth wave on the market, does not reach the requirement that analog gas absorbs situation far away.
Along with improving constantly of digitized degree, the waveform generation technique has also had a very big lifting, can make a standard signal source by digital mode fully, is used for analog gas absorbing state, directly as circuit debugging, replaced the whole optical module in front.And total digitalization, just with integrated, volume is little, and is in light weight.Therefore, come to improve the debugging efficiency of analog module in the optical fiber sensing system greatly with convenient and swift as a standard signal source.
Summary of the invention
In order to eliminate existing gas detection sensor system optics all factors partly to the influence of signal wave, improve circuit debugging efficient, shorten the R﹠D cycle, the utility model provides the standard signal source of gas absorption situation in a kind of analog optical fiber sensing detection gas.The utility model signal source produces the waveform signal as Fig. 2 (c), and the depression amplitude of waveform can be regulated corresponding to the difference of gas absorption degree in the air chamber, and can realize that by continuous debugging 1ppm's is corresponding one by one; Frequency adjustable, the sunk part of waveform can launch along with the broadening of whole waveform during frequency modulation.
Scheme of the present utility model produces the Wave data of the ripple that as (a) triangular wave among Fig. 2 and (b) caves in respectively with host computer, adopt the addition of corresponding phase amplitude to produce the Wave data of (c) output waveform then, deposit wave memorizer in, thereby produce waveform by frequency word control phase totalizer inquiry wave memorizer.
The technical solution of the utility model realizes in the following manner.
The standard signal source of gas absorption situation in a kind of analog optical fiber sensing detection gas, comprise frequency word register, phase accumulator, system clock frequency source, wave memorizer, host computer, D/A converter, low-pass filter, it is characterized in that the frequency word register is connected on the phase accumulator, provides frequency word for it; The output of phase accumulator is connected on the address wire of wave memorizer, and wave memorizer is connected on the D/A converter, and the system clock frequency source links to each other with D/A converter with phase accumulator respectively, for they provide the same base frequency; D/A converter is connected with low-pass filter, the feasible filtered circuit adjustment of signal wave through coming out after the D/A conversion; Host computer is connected respectively on wave memorizer and the frequency word register, writes Wave data and gives frequency word register write frequency word to wave memorizer.
A kind of above-mentioned standard signal source produces the method for standard signal, and step is as follows:
1), host computer is analyzed the triangular wave (being the reference waveform of using during gas detects) and the depression ripple (analog gas is to the absorption waveform of light) that collect in the Fibre Optical Sensor detection gas experiment in advance, host computer obtains the Wave data of triangular wave and depression ripple, host computer is made the Wave data that addition process produces output wave to the Wave data of triangular wave and depression ripple, and the output wave Wave data is write wave memorizer;
2), the system clock frequency source provides program-controlled clock signal provides the scan address for wave memorizer, the data of each address correspondence have just represented the range value of waveform on periodic sampling point like this;
3), host computer write frequency word in the frequency word register, frequency word is as the accumulated value of phase accumulator, phase accumulator is when each pulse reference clock input, frequency word is added up once, it exports the corresponding increment of the step-length that adds up accordingly, because the output of phase accumulator is connected on the address wire of wave memorizer, so the change of its output just is equivalent to table look-up, and so just can find the Wave data that is stored in the wave memorizer through lookup table mode;
4), the digital quantity input D/A converter that will table look-up and find, convert it to analog quantity;
5), under the effect in system clock frequency source, phase accumulator ceaselessly adds up, and namely ceaselessly tables look-up, and Wave data is all found delivered to D/A converter and be converted to analog quantity, thereby be synthesized waveform is whole;
6), be input to again through the analog quantity that obtains behind the D/A converter that low-pass filter is done smooth waveform, the decay stray wave is handled, obtain the waveform of wanting afterwards;
7), be subjected to the restriction of phase accumulator word length, after phase accumulator is added to certain value, its output will be overflowed, the address of wave memorizer will circulation primary like this, mean that namely output waveform circulates a week, therefore write different frequency words in the frequency word register, just different phase increments is used in representative, just can change overflowing the time of phase accumulator, under the constant situation of the clock frequency source of signal source, change output frequency;
The frequency adjustment of signal source is as follows:
If frequency word is d, the phase accumulator word length is N, and clock frequency is f
c, the output frequency of this signal source
Therefore the output frequency of visible system only with frequency word d, clock frequency f
c, phase accumulator word length N relevant, at clock frequency f
cFixedly the time, just can easily change output frequency f by changing frequency word d with the word length N of phase accumulator
0Owing in step 1), triangular wave and the two-part Wave data of depression ripple have been passed through processing in advance, be integrated into a Wave data, the Wave data of output waveform just, the broadening of integral body in the time of just can guaranteeing the absorption dip part along with frequency adjustment with a frequency word d controlled frequency like this and launching;
The reference frequency output of signal source: minimum output frequency
△ f
0The frequency resolution of signal source just, be subjected to the restriction of Nyquist's theorem, will add up twice at least overflowing in the cycle of a phase accumulator, just inquire about twice of wave memorizer sampling, can synthesize output waveform again, theoretic maximum output frequency is
Amplitude of the present utility model is regulated and can be regulated by Wave data in the change wave memorizer, by the experimental result data analysis to associated fiber sensing detection gas, can simulate the depression waveform corresponding with the 1ppm absorption intensity, just can control various amplitude under its different degrees of absorption easily with a coefficient relevant with gas concentration, air chamber length, gas pressure intensity then.Certainly, this step is to carry out before triangular wave and depression wave datum are integrated, and can guarantee the independent adjusting to the depression amplitude like this, the whole broadening of waveform when not influencing frequency modulation again.
The utility model has the advantages that major part is digital device, the integrated level height, volume is little, the precision height, stability is strong, can adjust the amplitude of absorption dip according to different degrees of absorption, and depression can be launched along with the broadening of whole waveform frequency modulation the time.Detect in the correlation engineering of gas at Fibre Optical Sensor, the opticator that can replace front end, directly produce the standard signal that analog gas absorbs situation, be used for follow-up analog module debugging, get rid of the many influence factors of opticator, improved the efficiency of research and development that absorption Fibre Optical Sensor detects this type systematic of gas concentration.
Description of drawings
Fig. 1. the absorption Fibre Optical Sensor of method of difference detects the part-structure figure of gas.
Wherein: 1, laser instrument, 2, beam splitter, 3, air chamber, 4, photodetector, 5, the output of flashlight waveform, 6, photodetector, 16, the output of reference light waveform.
Fig. 2. the corresponding situation synoptic diagram of the phase place the when type of waveform that relates in the Wave data collection and data are handled.
Wherein: (a), triangular wave (is the reference waveform of using during gas detects, can from before repeatedly Fibre Optical Sensor detect to gather the experiment of gas obtain), (b), depression ripple (analog gas is to the absorption of light), (c), output waveform (the final waveform output that produces of standard signal source of the present utility model).
Fig. 3. the structural representation of this standard signal source.
Wherein: 7, frequency word, 8, phase accumulator, 9, the system clock frequency source, 10, wave memorizer, 11, host computer, 12, Wave data, 13, D/A converter, 14, low-pass filter, 15, waveform output, 17, the frequency word register.
Embodiment
Below in conjunction with drawings and Examples the utility model is described further, but is not limited thereto.
Embodiment:
The utility model embodiment as shown in Figure 3, the standard signal source of gas absorption situation in a kind of analog optical fiber sensing detection gas, comprise frequency word register 17, phase accumulator 8, system clock frequency source 9, wave memorizer 10, host computer 11, D/A converter 13, low-pass filter 14, it is characterized in that frequency word register 17 is connected on the phase accumulator 8, provides frequency word 7 for it; The output of phase accumulator 8 is connected on the address wire of wave memorizer 10, and wave memorizer 10 is connected on the D/A converter 13, and system clock frequency source 9 links to each other with D/A converter 13 with phase accumulator 8 respectively, for they provide the same base frequency; D/A converter 13 is connected with low-pass filter 14, the feasible filtered circuit adjustment of signal wave through coming out after the D/A conversion; Host computer 11 is connected respectively on wave memorizer 10 and the frequency word register 17, writes Wave data 12 and gives frequency word register 17 write frequency words to wave memorizer 10.
Claims (1)
1. the standard signal source of gas absorption situation in the analog optical fiber sensing detection gas, comprise frequency word register, phase accumulator, system clock frequency source, wave memorizer, host computer, D/A converter, low-pass filter, it is characterized in that the frequency word register is connected on the phase accumulator, provides frequency word for it; The output of phase accumulator is connected on the address wire of wave memorizer, and wave memorizer is connected on the D/A converter, and the system clock frequency source links to each other with D/A converter with phase accumulator respectively, for they provide the same base frequency; D/A converter is connected with low-pass filter, the feasible filtered circuit adjustment of signal wave through coming out after the D/A conversion; Host computer is connected respectively on wave memorizer and the frequency word register, writes Wave data and gives frequency word register write frequency word to wave memorizer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201320122508 CN203148839U (en) | 2013-03-18 | 2013-03-18 | Standard signal source for simulating gas absorption condition in optical fiber sensing detection gas |
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| CN 201320122508 CN203148839U (en) | 2013-03-18 | 2013-03-18 | Standard signal source for simulating gas absorption condition in optical fiber sensing detection gas |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103196846A (en) * | 2013-03-18 | 2013-07-10 | 山东大学 | Standard signal source of gas absorption state in analog optical fiber gas sensing and detecting |
| CN103840797A (en) * | 2014-03-19 | 2014-06-04 | 成都引众数字设备有限公司 | High-precision frequency standard source |
| CN111157467A (en) * | 2019-12-31 | 2020-05-15 | 中国工程物理研究院激光聚变研究中心 | Active optical fiber core absorption coefficient measuring device and method |
-
2013
- 2013-03-18 CN CN 201320122508 patent/CN203148839U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103196846A (en) * | 2013-03-18 | 2013-07-10 | 山东大学 | Standard signal source of gas absorption state in analog optical fiber gas sensing and detecting |
| CN103196846B (en) * | 2013-03-18 | 2015-01-21 | 山东大学 | Standard signal source of gas absorption state in analog optical fiber gas sensing and detecting |
| CN103840797A (en) * | 2014-03-19 | 2014-06-04 | 成都引众数字设备有限公司 | High-precision frequency standard source |
| CN111157467A (en) * | 2019-12-31 | 2020-05-15 | 中国工程物理研究院激光聚变研究中心 | Active optical fiber core absorption coefficient measuring device and method |
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Granted publication date: 20130821 Termination date: 20150318 |
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| EXPY | Termination of patent right or utility model |