CN202903675U - Gas short-range laser remote sensing signal rapid processing circuit - Google Patents
Gas short-range laser remote sensing signal rapid processing circuit Download PDFInfo
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- CN202903675U CN202903675U CN 201220496999 CN201220496999U CN202903675U CN 202903675 U CN202903675 U CN 202903675U CN 201220496999 CN201220496999 CN 201220496999 CN 201220496999 U CN201220496999 U CN 201220496999U CN 202903675 U CN202903675 U CN 202903675U
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Abstract
The utility model relates to a gas short-range laser remote sensing signal rapid processing circuit, which comprises a laser device, a laser device driving module, a photoelectric detection module, an A/D (Analog to Digital) sampling converting circuit and a rapid digital signal processing circuit, wherein sine carrier wave and slope scanning signals are combined by a digital signal combining unit in the circuit into signals with the same cycle and phase to repeatedly drive the laser device. An A/D sampling converting module receives a sine triggering signal in the combined signals when being used for analog-digital conversion, the two signals have the same phase, the digital signal processing circuit completes the multiplying, integration, phase correction and low-pass filtering of digital signals, and characteristic signals for characterizing gas are output; and the phase correction and the low-pass filtering only need one path of signal. Through the combination of digital signal combined driving, synchronous triggering and digital signal processing, the response time and the signal processing time of laser spectrum gas detection are reduced; the dynamic monitoring efficiency of a work space is improved; and the circuit works stably and reliably. The circuit is used for a high-speed gas detecting and monitoring industry and the environment or occasions needing gas monitoring.
Description
Technical field
The utility model belongs to environmental science and spectroscopy technology field, and the laser telemetry that relates generally to gas is processed realization technology and circuit.A kind of gas short distance laser remote sensing signal fast processing circuit specifically.The short distance remote sensing that is used for flammable explosive gas detects and monitoring.
Background technology
The means that the gas prison detects mainly are to adopt the built-in type gas sensors such as all kinds of chemistry, metal oxide and infrared gas.The characteristics such as above-mentioned traditional gas sensor ubiquity poor selectivity, and sensitivity is low.And for inflammable, explosive, poisonous contour hazardous gas, the built-in type characteristics of traditional sensors have caused potential security risk.The in recent years practical progress of the maturation of spectrographic technique and laser technology makes laser spectrum remote sensing detection technique be successfully used in the detection of high-risk gas.Highly sensitive, the single and non-characteristics of inserting the gas-monitoring scene of selection gas that the method that laser spectrum remote sensing gas detects has for traditional gas detection method.Comparing the built-in type gas detection technology based on the detection of laser remote sensing characteristics or monitoring equipment, to have a minimum safety wind dangerous, and be loaded into the work efficiency that can significantly promote testing circuit on the mobile platform.
Takaya I seki (A portable remote methane sensor using a tunable diode laser.Meas.Sci.Technol.2000 (11): 594-602) proposed in the literature first a kind of based on DSP Portable laser telemetric circuit, J.Hodgkinson (Modelling and interpretation of gas detection using remote laser pointer.Spectrochimica Acta Part A, 2006 (63): 929-939.) Portable laser remote measurement performance has been carried out detailed analysis.Patent documentation (US6356350) has proposed a kind of digitizing solution of spectrum demodulation.
Can recognize that from document and patent existing Laser Driven has adopted continuous modulation signal, cause like this method that in the processing of photosignal, must adopt quadrature demodulation.Its processing speed is subject to the length restriction of digit chip clock and Processing Algorithm for digital processing method.Under given digit chip Clock, the structure of quadrature demodulation is fixed.Therefore will further improve the speed of processing, the response time of circuit is limited, has namely limited the monitoring velocity that this technology carries at mobile platform and has been restricted, thereby reduced the efficient of laser monitoring.
The utility model applicant is on the internet with regard to this theme, and at home and abroad patent documentation and the journal article retrieval of publishing are not yet found report or the document closely related and the same with the utility model.
The utility model content
The purpose of this utility model is the laser telemetry processing of circuit response time for present gas can't effectively adapt to the characteristics of monitoring platform high-speed mobile and the problem of patrolling and examining inefficiency that causes, a kind of quick response is provided, treatment circuit is simplified, signal processing time reduces greatly, the gas short distance laser remote sensing signal fast processing circuit that the detection of dynamic efficient between monitoring section is high.
The below describes the utility model:
The utility model is a kind of gas short distance laser remote sensing signal fast processing circuit, include: laser instrument, the laser instrument driver module, the photodetection module, signal processing circuit and corresponding A/D or D/A change-over circuit, the laser instrument driver module needs by sinusoidal carrier and sweep ramp signal stack rear drive laser works, tested gas is between laser instrument and the photodetector, the simulating signal that the photodetection module the receives number of delivering letters treatment circuit after the conversion of A/D sample circuit is processed, signal processing circuit of the present utility model is the fast digital signal processing circuit, the fast digital signal processing circuit includes: digital signal synthesis module and fast digital signal processing module, the digital signal synthesis module includes again sinusoidal stored digital signal, slope stored digital signal and digital signal synthesis unit, the parallel output of sinusoidal stored digital signal and slope stored digital signal is to the input end of digital signal synthesis unit, the output one tunnel of digital signal synthesis unit outputs to the laser instrument driver module through D/A, another road output is as the synchronizing signal of A/D sample circuit, and sinusoidal stored digital signal also is used for multiplier one tunnel input of fast digital signal processing module simultaneously; The fast digital signal processing module includes: multiplier, integrator, phase correction module and low-pass filter, interconnect successively, multiplier wherein receives output and the sinusoidal stored digital signal of A/D sample circuit simultaneously, above-mentioned two signal phases consistent, the fast digital signal processing unit is output as for the characteristic signal that characterizes gas; Phase correction module in the described fast digital signal processing unit and the signal of low-pass filter are only processed and are needed one the tunnel.
The utility model obtains for the phase correction of the characteristic signal that characterizes gas and low-pass filtering and only needs one the tunnel, because the output of A/D sample circuit and sinusoidal stored digital signal are synchronous signals, just need not consider the impact of phase place, the setting of therefore also having saved one tunnel phase correction module and low-pass filtering, also be that phase correction module and low-pass filter only need one the tunnel, circuit structure is simplified, and the processing speed of data is improved.Obtain at last for the characteristic signal that characterizes gas.It is one tunnel step process that the utility model reasonably designs the two-way step process that can optimize quadrature demodulation in follow-up digital signal processing to the Laser Driven input signal.Accelerated thus the speed that signal is processed, the response time of having improved observation circuit, can work efficiently for the gas-monitoring of high-speed mobile or the observation circuit of high-speed mobile.
Continuous modulation signal has been adopted in existing Laser Driven modulation, causes the method that must adopt quadrature demodulation in the processing of photosignal to realize satisfying the characteristic signal that characterizes gas.It is that slight photo-electric signal detects common method that quadrature demodulation detects.By reference signal and the realization narrow-band filtering that multiplies each other that receives signal.Because carrier phase is uncertain, utilize orthogonality principle to eliminate the impact of phase place.Signal is processed to be needed to process the characteristic signal that just can obtain for characterizing gas through two-way.The utility model synthesizes by digital signal synthesis unit offset of sinusoidal carrier wave and sweep ramp signal, make its fixing composite signal periodically repeat input signal as the Laser Driven module, thereby guaranteed the consistance of the sinusoidal carrier phase place of each repetition period.Synchronous triggering signal of initial transmission in cycle composite signal input Laser Driven module.By above-mentioned technical finesse, under the control of synchronous triggering signal, laser action is gathered by A/D sample conversion module in the photosignal that the photodetection module produces, and sends into digital signal processing module and processes.Because each sinusoidal carrier signal phase place is consistent, when data are processed, only need carries out carrying out signal with respect to a road in the orthogonal demodulation method two-way and process.Simplify circuit structure, improved processing speed, especially adapted to the speed of digital signal processing.
Realization of the present utility model also is: the fast digital signal processing unit realized by digital signal processing chip DSP, comprising: multiplier, integrator, phase correction module and low-pass filter.It is fast that digital signal processing chip DPS has processing speed, and the advantages such as low-power consumption only need multiplier, integrator, phase correction module and the low-pass filter mode with program is write and can realize.
Realization of the present utility model also is: the fast digital signal processing unit realized by programmable logic device (CPLD), comprising: multiplier, integrator, phase correction module and low-pass filter.Programmable logic device (CPLD) is another kind of digital signal processing chip, have the characteristics such as concurrent working, adopting programmable logic device (CPLD) to realize that multiplier, integrator, phase correction module and the low-pass filter of fast digital signal processing unit also only need required circuit write in the mode of software gets final product, easily change convenient for maintaining.
Realization of the present utility model also is: digital signal processing unit realized by programming logic gate array FPGA, comprising: multiplier, integrator, phase correction module and low-pass filter.Adopt programming logic gate array FPGA to realize multiplier, integrator, phase correction module and low-pass filter, not only cost is low, the advantages such as easy realization.
Slowly the problem of patrolling and examining inefficiency that causes for the laser telemetry translational speed of gas owing to the utility model, drive, trigger synchronously and quick+digital signal processing combination by digital signal synthesis, optimization improves the response time of detecting based on laser spectrum gas based on the processing speed of the laser spectrum signal of Modulating Diode Laser absorption spectrum method (TDLAS).Provide a kind of processing time of signal greatly to reduce; Interval dynamic monitoring efficient is high; The reliably quick short distance laser remote sensing gas-monitoring circuit of working stability.The utility model can be widely used in that gas detects and the monitoring industry, also can be applicable to working environment or the occasion that need to detect and monitor associated gas.
Description of drawings:
Fig. 1 is the quadrature demodulation theory diagram of prior art;
Fig. 2 is theory diagram of the present utility model;
Fig. 3 is the analogous diagram of the demodulation characteristic signal waveform under the delay condition of the present utility model.
Embodiment:
Below in conjunction with accompanying drawing the utility model is further described
Embodiment 1:
Referring to Fig. 2, the utility model is a kind of gas short distance laser remote sensing signal fast processing circuit, referring to Fig. 2, include: laser instrument, the laser instrument driver module, the photodetection module, signal processing circuit and corresponding A/D or D/A change-over circuit, the laser instrument driver module needs by sinusoidal carrier and sweep ramp signal stack rear drive laser works, tested gas is between laser instrument and the photodetector, the simulating signal that the photodetection module the receives number of delivering letters treatment circuit after the conversion of A/D sample circuit is processed, signal processing circuit is extracted sinusoidal carrier signal in the drive circuit for laser simultaneously as demodulated reference signal, signal processing circuit of the present utility model is the fast digital signal processing circuit, the fast digital signal processing circuit includes: digital signal synthesis module and digital signal processing module, digital signal synthesis module include again sinusoidal stored digital signal, slope stored digital signal and digital signal synthesis unit.The driving signal of digital signal synthesis unit output is to have eliminated the phase differential periodic drive signal after sine sweep signal and slope carrier signal are synthesized, and digital signal processing module includes: multiplier, integrator, phase correction and low-pass filter.The work of laser instrument driver module drive laser is exported light frequency continuously and the laser of light intensity sinusoidal variations, the Laser Driven module need be sent into the laser instrument driver module after the stack by the generation sinusoidal carrier of the digital signal synthesis unit in the fast digital signal processing circuit and sweep ramp signal, and tested gas is between laser instrument and the photodetection module.The A/D sample conversion receives the simulated photoelectric signal of photodetection module, the sinusoidal trigger pip of receiving digital signals synthesis unit simultaneously, above-mentioned two signal phases consistent.A/D sample conversion signal is converted to digital signal access multiplier through the simulated photoelectric signal that the synchronizing signal of signal synthesis unit triggers the photodetection module, multiplier carries out the phase multiplication to this digital signal and storage signal, storage signal is the sinusoidal carrier signal synchronous triggering signal namely in the digital signal synthesis unit, and storage signal and sinusoidal carrier signal are with the cycle same-phase in other words; The multiplier of signal processing module is received integrator with multiplied result and is carried out computing, signal after the integral operation obtains for the characteristic signal that characterizes gas through phase correction and low-pass filter successively, and phase correction and the low-pass filtering obtained for the characteristic signal that characterizes gas only need one the tunnel.In this example, digital signal processing module is realized by digital signal processing chip DSP.
Continuous modulation signal has been adopted in existing Laser Driven modulation, causes the method that must adopt quadrature demodulation in the processing of photosignal.It is that slight photo-electric signal detects common method that quadrature demodulation detects.By reference signal and the realization narrow-band filtering that multiplies each other that receives signal.Because carrier phase is uncertain, utilize orthogonality principle to eliminate the impact of phase place.Fig. 2 has provided the theory diagram that the quadrature demodulation of signal detects in the prior art.Signal is processed as seen from Figure 2 needs to process the characteristic signal that just can obtain for characterizing gas through two-way.
The utility model synthesizes by digital signal synthesis unit offset of sinusoidal carrier wave and sweep ramp signal, make its fixing composite signal periodically repeat input signal as the Laser Driven module, thereby guaranteed the consistance of the sinusoidal carrier phase place of each repetition period.Synchronous triggering signal of initial transmission in cycle composite signal input Laser Driven module.By above-mentioned technical finesse, under the control of synchronous triggering signal, laser action is gathered by A/D sample conversion module in the photosignal that the photodetection module produces, and sends into digital signal processing module and processes.Because each sinusoidal carrier signal phase place is consistent, when data are processed, only need carries out carrying out signal with respect to a road in the orthogonal demodulation method two-way and process.See Fig. 2.The utility model, is laid a good foundation for further improving the quick response of gas-monitoring circuit for the synthetic processing of laser instrument driving signal.
This circuit drives the modulation input end with output terminal and the laser instrument of the signal synthesis unit of this circuit and is connected in use, and the output terminal of photodetector module is connected with the A/D input end of this circuit.This circuit and external laser instrument and drive circuit for laser, photodetector, place laser instrument and photodetector by the coaxial scheme of catoptron, this circuit and outer relay part can be placed in the portable case, be applicable to the demand that various mobile prisons detect.
Embodiment 2: the formation of gas short distance laser remote sensing signal fast processing circuit is with embodiment 1, digital signal processing unit is realized by the fixed point TMS320C55XX series DSP of digital signal processing chip Texas Instrument (TI), is utilized software programming to realize respectively multiplier, integrator, phase correction and low-pass filter in digital signal processing chip DSP exactly.Take TMS320C55XX series C5509a as example, realize that gas short distance laser remote sensing signal fast processing circuit working step is as follows: 1, the external A/D modular converter of C5509a (for example: the ADS8325 of TI), the D/A modular converter (for example: the DAC8534 of TI) and the LCD demonstration, wherein the A/D modular converter is connected with the photodetection module, the D/A modular converter is connected with the modulation input end of laser instrument driver module, and LCD shows and is connected with the 6PIO port of C5509a.2, the work setting of C5509aDSP, C5509a has three MCBSP (multichannel buffered serial port), one of them is set for gathering port, this collection port is connected with DMA (direct memory enters), in conjunction with DMA address characteristics able to programme, the pingpang that realizes data gathers the external A/D modular converter of this port; The output terminal that one of them port is the digital synthesis signal unit is set, and this output port links to each other with DMA, the address of sinusoidal and slope numbers pile up signal is set, the external D/A modular converter of this port in the control register of DMA; It is SD card storage IO interface that one of them port is set, for the treatment of data storage.3, timer is set and interrupts, be used for starting simultaneously the signal that the required modulation signal of one road DMA+MCBSP output laser driver module and one road DMA+MCBSP gather the photodetector module.4, finish down trigger according to the signals collecting that gathers the DMA+MCBSP passage and start the fast signal Processing tasks, this task comprises the ingredient of fast signal processing unit shown in Figure 2.5, finish the sign of setting according to the fast signal Processing tasks, start detection result's demonstration and store tasks.
Embodiment 3: the formation of gas short distance laser remote sensing signal fast processing circuit is with embodiment 1-2, digital signal processing unit is wherein realized by programmable logic device (CPLD), is to realize multiplier, integrator, phase correction module and low-pass filter by software programming equally.Concrete function realizes being similar to the realization of DSP.
Embodiment 4: the formation of gas short distance laser remote sensing signal fast processing circuit is with embodiment 1-3, digital signal processing unit is wherein realized by programming logic gate array FPGA, consists of multiplier, integrator, phase correction module and low-pass filter by software programming.And phase correction module and low-pass filter only need one the tunnel.Concrete function realizes being similar to the realization of DSP.
Embodiment 5: the formation of gas short distance laser remote sensing signal fast processing circuit is with embodiment 1-4, the utility model utilizes the digital signal synthesis unit with sine and the synthetic rear cycle drive laser of ramp signal, drive pulse signal of original transmission to the signal acquisition process unit in the cycle, the trigger pip collecting work begins, and can guarantee that like this phase delay is controlled at 2E-7s.Fig. 2 has provided the fast processing schematic block circuit diagram that the utility model provides.Laser signal is being sent into the fast digital signal processing circuit that DSP be made of after the digital-to-analog conversion through survey receiving under the trigger pulse control, digital signal be stored in that carrier signal among the DSP multiplies each other, export after integration, Phase Processing and the low-pass filtering.Wherein because the control of initial pulse has guaranteed for the composite signal that drives consistent with the carrier signal phase that is stored in DSP on phase place.Can simplify thus the complexity of digital phase sensitivity detection algorithm, accelerate the processing speed of signal, and then be applicable to the testing goal of high-speed mobile.In order to verify the fast moving detection method to the impact of signal demodulation characteristic line, utilize emulation technology to analyze small phase place variation the demodulation characteristic signal is analyzed.For the impact of emulation micro phase delay, the sampling rate to reality in the simulation has enlarged 10 times.For the 100ksps sampling rate that reality adopts, the interval of sampled point is 100 times of actual photoelectricity receive delay.Consider the response time of photodetector and D/A converting circuit, enlarging original ten times time delay.Lower triangle line is the demodulation second harmonic absorption signal without phase delay among Fig. 3, the filled circles line is the utility model at the demodulation second harmonic signal that postpones with respect to actual samples point interval 1/10th, and dotted line then is the demodulation second harmonic signal that actual single sampled point postpones.Simulation result shows that 1/10th delay is substantially to overlap with undelayed, and amplitude differs 1%.And phase delay reaches a sampled point during time, and amplitude differs near 15%.Simulation result shows the utility model compared with the prior art, because the time delay that Laser emission receives can be ignored with respect to the signal errors that sampling delay causes, and synchronously triggering has further guaranteed the phase place initial error of modulation reference signals and restituted signal, thereby in short distance remote measurement situation, simplified conventional orthogonal demodulation method and circuit, reduced thus the processing time of signal.
Embodiment 6: the formation of gas short distance laser remote sensing signal fast processing circuit is with embodiment 1-5, the unmanned non-contact monitoring in the way that can be used for driving when intoxicated.This circuit is installed in the road top, and laser instrument and photodetection module adopt optical transmitting and receiving one body technique to place same position.Utilize the laser telemetry characteristic, laser is injected pilothouse by windshield and is realized the human pilot detection of whether drinking, and this fast monitored circuit is particularly suitable for the monitoring of high speed traveling.
Embodiment 7: the formation of gas short distance laser remote sensing signal fast processing circuit can be used for city natural gas pipe network and leaks safety monitoring with embodiment 1-5.This circuit is installed on the vehicle-mounted mobile platform, and the quick response of this circuit is processed, and can bring into play the characteristic that automobile high-speed moves, and improves the monitoring number of times of extensive area, thereby improves the efficient of detecting/monitoring.
Traditional quadrature demodulation unit is inconsistent because of carrier phase, needs sinusoidal and after the cosine two-way divides level signal to process, again through low pass, quadratic sum is opened computing can the realization character signal.The utility model digital signal synthesis unit synthesizes the consistent signal of periodic phase with sinusoidal carrier and slope sweep signal and repeats drive laser.A/D sample conversion module is in the analog-to-digital sinusoidal trigger pip that receives simultaneously in the composite signal, two signal phases are consistent, digital signal processing circuit is finished the multiplying each other of digital signal, integration, phase correction and low-pass filtering, is output as the characteristic signal that characterizes gas; Phase correction and low-pass filtering only need one the tunnel.Drive, trigger synchronously and the digital signal processing combination by digital signal synthesis, reduced response time and signal processing time that laser spectrum gas detects; Improve the dynamic monitoring efficient of operation interval; Working stability is reliable.
The utility model has been simplified the passage that modulation signal is processed, and then has reduced at double the time that signal is processed.Provide a kind of processing time of signal greatly to reduce; Interval dynamic monitoring efficient is high; The reliably quick short distance laser remote sensing gas-monitoring circuit of working stability.The utility model can be widely used in gas detection and monitoring industry, also can be used for environment or occasion that high-speed gas detects the monitoring industry and needs gas is monitored.
Claims (4)
1. gas short distance laser remote sensing signal fast processing circuit, include: laser instrument, the laser instrument driver module, the photodetection module, signal processing circuit and corresponding A/D or D/A change-over circuit, the laser instrument driver module needs by sinusoidal carrier and sweep ramp signal stack rear drive laser works, tested gas is between laser instrument and the photodetector, the simulating signal that the photodetection module the receives number of delivering letters treatment circuit after the conversion of A/D sample circuit is processed, it is characterized in that: described signal processing circuit is the fast digital signal processing circuit, the fast digital signal processing circuit includes: digital signal synthesis module and fast digital signal processing module, the digital signal synthesis module includes again sinusoidal stored digital signal, slope stored digital signal and digital signal synthesis unit, the parallel output of sinusoidal stored digital signal and slope stored digital signal is to the input end of digital signal synthesis unit, the output one tunnel of digital signal synthesis unit outputs to the laser instrument driver module through D/A, another road output is as the synchronizing signal of A/D sample circuit, and sinusoidal stored digital signal also is used for multiplier one tunnel input of fast digital signal processing module simultaneously; The fast digital signal processing module includes: multiplier, integrator, phase correction module and low-pass filter, interconnect successively, multiplier wherein receives output and the sinusoidal stored digital signal of A/D sample circuit simultaneously, above-mentioned two signal phases consistent, the fast digital signal processing unit is output as for the characteristic signal that characterizes gas; Phase correction module in the described fast digital signal processing unit and the signal of low-pass filter are only processed and are needed one the tunnel.
2. gas short distance laser remote sensing signal fast processing circuit according to claim 1, it is characterized in that: described fast digital signal processing unit realized by digital signal processing chip DSP, comprising: multiplier, integrator, phase correction module and low-pass filter.
3. gas short distance laser remote sensing signal fast processing circuit according to claim 1, it is characterized in that: described digital signal processing unit realized by programmable logic device (CPLD), comprising: multiplier, integrator, phase correction module and low-pass filter.
4. gas short distance laser remote sensing signal fast processing circuit according to claim 2, it is characterized in that: described digital signal processing unit realized by programming logic gate array FPGA, comprising: multiplier, integrator, phase correction module and low-pass filter.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108571658A (en) * | 2018-08-01 | 2018-09-25 | 无锡麦道电子科技有限公司 | Gas piping ultrasonic leak detector |
| CN111044485A (en) * | 2019-12-04 | 2020-04-21 | 清华大学合肥公共安全研究院 | Tunable laser absorption harmonic demodulation circuit and method based on FPGA (field programmable Gate array) synchronous signals |
| CN114487478A (en) * | 2022-01-26 | 2022-05-13 | 西安交通大学 | MOEMS acceleration sensor system based on quadrature carrier modulation |
-
2012
- 2012-09-18 CN CN 201220496999 patent/CN202903675U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108571658A (en) * | 2018-08-01 | 2018-09-25 | 无锡麦道电子科技有限公司 | Gas piping ultrasonic leak detector |
| CN111044485A (en) * | 2019-12-04 | 2020-04-21 | 清华大学合肥公共安全研究院 | Tunable laser absorption harmonic demodulation circuit and method based on FPGA (field programmable Gate array) synchronous signals |
| CN114487478A (en) * | 2022-01-26 | 2022-05-13 | 西安交通大学 | MOEMS acceleration sensor system based on quadrature carrier modulation |
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