CN100378438C - Time division multiplex optical fiber grating sensing testing system based on CPLD - Google Patents
Time division multiplex optical fiber grating sensing testing system based on CPLD Download PDFInfo
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Abstract
The present invention relates to a time division multiplex optical fiber grating sensing testing system based on CPLD, which belongs to the technical field of optical fiber sensing measure. The present invention solves the problems that the optical fiber grating multiplex number of the existing sensing system based on wavelength division multiplex technique is limited, the sensing system based on time division multiplex technique has a complicated structure and poor using flexibility, and the sensing system can not realize simultaneous monitoring for a plurality of sensing elements. The output reflection light of a coupler (3) of the present invention is input to signal input ends of m channel switches (7) through a photoelectric signal converter (5), a modulation signal is output to an electro-optic modulator (2) by a CPLD control circuit (6), and m switch conducting control signals are output to control signal input ends of the m channel switches (7) by the CPLD control circuit (6) so as to make the sensing information of each optical fiber grating sensing element respectively enter into a sensing signal detector (8) to be tested through the channel switches (7) according to time series synchronization. The present invention can modify periods and duty ratios of a pulse modulation signal and the time series of a time delay switch control signal according to need so as to greatly enhance the flexibility of the system.
Description
Technical field
The invention belongs to the Fibre Optical Sensor field of measuring technique, it relates to a kind of networked fiber grating sensing system.
Background technology
Fiber grating soft comparatively speaking (arranging more flexible), sensing loop is easy to implant or can the performance and the structure of material not be impacted attached to body structure surface, can be used to monitor the information of strain, temperature and structural intergrity aspect.Compare with the traditional sensors of other type, price that let it be to the greatest extent is still than higher, but its great advantage is its reusable, carries out networked sensing.Make that like this each sensor average price is lower, therefore concerning extensive Application in Sensing, optical fiber grating sensing network should be first-selected technology.
In existing technology, Chinese patent CN1384341A disclosed " fiber-optic grating sensor that a kind of pressure and temperature detect simultaneously ", Chinese patent CN1563916A disclosed " a kind of fiber-optical grating temperature sensor and manufacture method thereof ", Chinese patent CN1412530A " the single fibre grating method for packing and the sensor thereof of strain and temperature simultaneously measuring ", it has been realized by fiber grating measurement to be measured, and it is relatively simple for structure, performance is more stable, but they have not given play to the advantage of fiber grating, realize networked sensing, the sensor cost of single grating is also relatively more expensive, and cost performance is not high.
The multiplex technique of optical fiber grating sensing network mainly contains wavelength-division multiplex, two kinds of structures of time division multiplex.Wavelength-division multiplex technique is comparatively ripe, Chinese patent CN1527028A " a kind of optical fiber grating sensing testing system that is used for the oil-gas pipeline detection ", the Chinese patent CN1614359A method of multi-channel optical fibre raster sensor high-sensitivity measurement " realize " is based on that wavelength-division multiplex technique succeeds in developing.But fiber grating wavelength-division multiplex sensing technology is an optical fiber grating sensing unit to be cut apart in certain wavelength coverage light source, each sensing unit occupies certain wavelength coverage, the different corresponding wavelength of sensing unit can not be overlapped, this makes the optical fiber optical grating multiplexing number be subjected to the restriction of light source bandwidth, and the strain measurement scope of each optical fiber grating sensing unit is subjected to the restriction of adjacent two grating wavelengths, and is not too suitable in the structure of a large amount of sensing of needs unit, big strain measurement scope.
Fiber grating time division multiplex sensing technology is to be connected in series many sensings unit on same optical fiber, light signal distributes between different sensing unit according to sequential and discerns, so the number of its reusable sensor in theory can be a lot, be more suitable for sensing requirement in catenetization.(Weis RS, Kersey AD, Berkoff T A, " A four-element fiber grating sensor array with phase-sensitivedetection ", IEEE Photon.Technol.Lett., 1994,1469～1472) and (Yu Youlong 6 (12):, Tan Huayao, He Hailv etc., " the fiber grating system time domain address lookup technology of high resolving power single channel output ", " optics journal ", Vol.21 No.7:874-877) utilizes time-division multiplex technology that the optical fiber grating sensing unit that is serially connected on the same optical fiber has successfully been carried out strain detecting.But they adopt the single channel way of output, can only inquire about single sensing unit at every turn, do not possess real-time monitoring capability.And it need add auxiliary light signal modulating pulse instruments such as source, delay controller take place, and makes that the integrated level of system is not high, and cost performance is not high, is difficult to realize practicability.Pulse-modulated signal, time delayed signal are not same Clock managements, and each device timing differential causes the phenomenon of sequential logic confusion easily.System is controlled by special clock signal in addition, will be aplanatism between sensing unit and distribute, to guarantee accurate time-delay, be convenient to coordinate the operation between electronic switch and the impulse source, in a single day system designs, and can't adjust again, make sensing network lack dirigibility, be difficult to realize large batch of commercialization.
Summary of the invention
Be restricted in order to solve existing sensor-based system optical fiber optical grating multiplexing number based on wavelength-division multiplex technique, reach complex structure based on the sensor-based system of time-division multiplex technology, use very flexible, can not realize a plurality of sensing unit is carried out the while problems of monitoring, the invention provides a kind of time division multiplex optical fiber grating sensing testing system based on CPLD, with respect to sensor-based system based on wavelength-division multiplex technique, it is not subjected to the restriction of light source bandwidth, increased the number of optical fiber grating sensing unit greatly, with respect to sensor-based system based on time-division multiplex technology, it has greatly increased the dirigibility that system detects, and can be used for a plurality of optical fiber grating sensing unit is monitored in real time; And be used for realizing health monitoring to large and complex structure.
Device of the present invention is made up of light source generator 1, electrooptic modulator 2, coupling mechanism 3, the optical fiber 4, CPLD control circuit 6, a m channel switch 7, a m transducing signal detecting device 8, photoelectric signal converter 5 and the system clock circuit 9 that are serially connected with the 4-1 of m grating sensing unit, the output terminal of light source generator 1 connects the light input end of electrooptic modulator 2, the light output end of electrooptic modulator 2 connects the input end of coupling mechanism 3, and the incident light that has grating sensing information of coupling mechanism 3 outputs is coupled in the optical fiber 4; The modulation signal output terminal of CPLD control circuit 6 connects the modulation signal input end of electrooptic modulator 2, the reflected light of coupling mechanism 3 outputs is input to the signal input part of m channel switch 7 by photoelectric signal converter 5, the signal output part of m channel switch 7 connects the input end of m transducing signal detecting device 8 respectively, the m of CPLD control circuit 6 switch delay control signal output terminal connects the signal input end of m channel switch 7 respectively, and the output terminal of system clock circuit 9 connects the clock signal input terminal of CPLD control circuit 6; Described photoelectric signal converter 5 is used for the heat transfer agent of Wavelength-encoding is converted to the heat transfer agent of phase encoding, and wherein m is the natural number of non-zero.
Principle of work: it is that the light-pulse generator of f is injected in the optical fiber of being made up of the first 4-1 of m grating sensing 4 that pulse that CPLD control circuit 6 sends control electrooptic modulator 2 becomes frequency with the continuous wide band optical modulation, the incident pulse light that enters optical fiber is modulated into the reflection light pulse string with certain hour interval that has heat transfer agent by fiber grating, and this time interval is by the spacing decision of the 4-1 of each grating sensing unit in the fiber grating string; The present invention has these in the switch arrays of train of impulses through being amplified into m channel switch 7 compositions in the time interval, and distributed m channel for the transmission of this pulse information, the unlatching of this m channel is by the switch delay control signal decision of CPLD control circuit 6 outputs, this switch delay control signal comes channel switch 7 is carried out gating according to the sequencing of m pulse Returning switch time of sensing grating string, guarantees that (1≤i≤m) transducing signal of the 4-1 of grating sensing unit is exported by i channel switch 7 from i.The present invention adopts system clock circuit 9 to provide same clock signal for modulation generating circuit and switch delay control signal generation circuit.
The present invention utilizes the online programmable function of programmable logic device (CPLD), realized that time division multiplex optical fiber grating sensing testing system can be according to the cycle of the actual conditions online modification pulse-modulated signal at scene and the sequential of dutycycle and delay switch control signal, and can revise the time delay of channel control at any time, greatly increased the dirigibility of system, exempted time domain address lookup technology to the equally spaced requirement of sensing unit from principle.The present invention adopts the multidiameter delay addressing mode to the time divisional processing of signal, has reduced the parasitic noise of switch greatly, has improved the signal to noise ratio (S/N ratio) of signal greatly; Pulse-modulated signal, time delayed signal realized with clock management, avoided the phenomenon of the sequential logic confusion that each device timing differential brings.Adopt system of the present invention can realize large and complex structure as the real-time health monitoring of bridge, large-scale dam, pipe laying, tunnel, mining site, nuclear storage container, buildings, road etc.
Description of drawings
Fig. 1 is a structural representation of the present invention, and Fig. 2 is the inner structure synoptic diagram of CPLD control circuit 6 of the present invention; Fig. 3 is the corresponding relation synoptic diagram of theoretic switch controlling signal and transducing signal; Fig. 4 is electrooptical modulation signal a, electronic switch Continuity signal b and arrive the corresponding relation synoptic diagram with sensing grating string heat transfer agent electronic impulse string c of electronic switch during for practical application of the present invention.
Embodiment
Embodiment one: referring to Fig. 1, the device of this embodiment is made up of light source generator 1, electrooptic modulator 2, coupling mechanism 3, transducing signal detecting device 8, the optical fiber 4, CPLD control circuit 6, a m channel switch 7, a m transducing signal detecting device 8, photoelectric signal converter 5 and the system clock circuit 9 that are serially connected with the 4-1 of m grating sensing unit, the output terminal of light source generator 1 connects the light input end of electrooptic modulator 2, the light output end of electrooptic modulator 2 connects the input end of coupling mechanism 3, and the incident light of coupling mechanism 3 outputs is coupled in the optical fiber 4; The modulation signal output terminal of CPLD control circuit 6 connects the modulation signal input end of electrooptic modulator 2, the reflected light that has grating sensing information of coupling mechanism 3 outputs is input to the signal input part of m channel switch 7 by photoelectric signal converter 5, the signal output part of each channel switch 7 connects the input end of transducing signal detecting device 8 respectively, the m of CPLD control circuit 6 switch delay control signal output terminal connects the signal input end of m channel switch 7 respectively, the output terminal of system clock circuit 9 connects the clock signal input terminal of CPLD control circuit 6, and wherein m is the natural number of non-zero.
Embodiment two: referring to Fig. 1, this embodiment with the difference of embodiment one is: described photoelectric signal converter 5 is used for the heat transfer agent of Wavelength-encoding is converted to the heat transfer agent of phase encoding, described photoelectric signal converter 5 comprises the non-equilibrium michelson interferometer 5-1 of full optical fiber, saw-toothed wave generator 5-2, amplifier 5-4, photodetector 5-3 and piezoelectric ceramics 5-5, the reflected light coupling with grating sensing information of coupling mechanism 3 outputs enters among the non-equilibrium michelson interferometer 5-1 of full optical fiber, dilatation takes place in the driven piezoelectric ceramics 5-5 of saw-toothed wave generator 5-2 output, the flexible two ends of piezoelectric ceramics 5-5 are fixed on the arm of the non-equilibrium michelson interferometer 5-1 of full optical fiber, the light signal of the non-equilibrium michelson interferometer 5-1 output of full optical fiber is converted to electric signal by photodetector 5-3, and this electric signal is transferred to the signal input part of each channel switch 7 by amplifier 5-4.Other compositions and annexation thereof are identical with embodiment one.The brachium mean value of the non-equilibrium michelson interferometer 5-1 of described full optical fiber is 111cm, and its arm length difference is 3.19mm, the refractive index of fiber medium be the reflectivity of 1.4489, two end mirrors near 85%, the contrast of striped is 0.3; The frequency of described piezoelectric ceramics 5-5 drive signal is 80Hz, and the peak-to-peak value of drive signal is 9.2V because piezoelectric ceramics can not be operated in the negative voltage pattern, so that the voltage DC component on the piezoelectric ceramics (PZT) is 10V.The non-equilibrium michelson interferometer 5-1 of above-mentioned full optical fiber can also replace with the device of other types such as the nonequilibrium Mach-Zehnder interferometer of full optical fiber, as long as can make described photoelectric signal converter 5 realize its function.It is the chip of AD8008 that described amplifier 5-4 adopts model.The scope of the operation wavelength of used photodetector 5-3 is 800～1800nm, and detector gain is 165V/mw.
Embodiment three: referring to Fig. 1, this embodiment with the difference of embodiment one is: described light source generator 1 comprises fibre optic isolater 1-1 and wideband light source 1-2, the output terminal of wideband light source 1-2 connects the input end of fibre optic isolater 1-1, and the output terminal of fibre optic isolater 1-1 connects the light input end of electrooptic modulator 2.Other compositions and annexation thereof are identical with embodiment one.
Embodiment four: referring to Fig. 1, this embodiment with the difference of embodiment one is: described each transducing signal detecting device 8 comprises bandpass filter 8-1 and phasometer 8-2, the input end of the signal output part connecting band bandpass filter 8-1 of channel switch 7, the output terminal of wave filter 8-1 connects the input end of phasometer 8-2.Other compositions and annexation thereof are identical with embodiment one.
Embodiment five: referring to Fig. 1 and Fig. 2, the difference of this embodiment and embodiment one is: described CPLD control circuit 6 by modulation signal not gate gating circuit 6-1, counter 6-2, first with door 6-3, second with a 6-8, first or 6-4, count resets not gate gating circuit 6-7, at least one first trigger 6-5 and organize delay switch control signal generation circuit 6-6 more and form; The clock signal input terminal of the output terminal linkage counter 6-2 of system clock circuit 9 and the trigger end of all first trigger 6-5, determine the logical sequence of count resets not gate gating circuit 6-7 according to the frequency of clock period and required modulation signal, the multidigit binary-coded information of counter 6-2 output is input to the reset terminal of counter 6-2 by count resets not gate gating circuit 6-7 and second with a 6-8; Determine the logical sequence of modulation signal not gate gating circuit 6-1 according to the dutycycle of required modulation signal, the multidigit binary-coded information of counter 6-2 output successively by modulation signal not gate gating circuit 6-1, first with door 6-3 and first or a 6-4 after be input to the signal input part of all first trigger 6-5, the output terminal of all first trigger 6-5 all connects the modulation signal input end of electrooptic modulator 2, a plurality of first trigger 6-5 are connected in parallel, in order to increase the driving force of modulation signal; Each group delay switch control signal generation circuit 6-6 is by a plurality of not gate gating circuit 6-6-1, the a plurality of the 3rd with the door 6-6-2, second or door 6-6-3 and the second trigger 6-6-4 form, the output terminal of system clock circuit 9 connects the trigger end of all second trigger 6-6-4, in every group of delay switch control signal generation circuit 6-6, a plurality of output terminals of counter 6-2 connect the input end of a plurality of not gate gating circuit 6-6-1 respectively, the output terminal of each not gate gating circuit 6-6-1 is connected second or the input end of 6-6-3 by one the 3rd with door 6-6-2, second or the output terminal of door 6-6-3 connect the signal input part of the second trigger 6-6-4, the output terminal of the second trigger 6-6-4 connects the signal input end of a channel switch 7.In each group delay switch control signal generation circuit 6-6, the sequential logic of not gate gating circuit 6-6-1 is by the cycle of required modulation signal and the time decision of fiber grating sensing signal arrival channel switch.Produce channel switch (1～m) control signal by the second different trigger 6-6-4 according to different fiber grating sensing signals respectively according to its different time of return.Other compositions and annexation thereof are identical with embodiment one.
Embodiment six: referring to Fig. 1 to Fig. 2, this embodiment with the difference of embodiment five is: the information source of this embodiment is the optical fiber 4 that contains 10 4-1 of grating sensing unit, the grid of each 4-1 of grating sensing unit are long to be 1cm, spacing between two 4-1 of grating sensing unit is 10m, the wavelength of the 4-1 of each grating sensing unit is respectively: 1537.125nm, 1539.475nm, 1543.456nm, 1545.336nm, 1547.153nm, 1549.171nm, 1551.455nm, 1553.107nm, 1555.393nm, 1557.740nm, their reflectivity is all more than 90%, and the reflection bandwidth of each 4-1 of grating sensing unit is all about 0.15nm.Described system clock circuit 9 output frequencies are the clock signal of 125MHZ, and the cycle is 8ns.The frequency of the electrooptical modulation pulse of described electrooptic modulator 2 is 500KHZ, and the electrooptical modulation duty of ratio is 2%, and the peak-to-peak value of electrooptical modulation pulse is 3.6V, and DC level is 0V; Its extinction ratio is 37.5dB, and the insertion loss is 3.6dB.The complex programmable logic control chip ispMACH4064 that described CPLD control circuit 6 adopts lattice company to produce, wherein counter 6-1-1 is eight up counters.Because the fundamental clock of system is 8ns, the frequency of required modulation signal is 500KHZ, dutycycle is 2%, then need counter 6-2 counting 250, so when eight up counters count down to " 1111; 1010 ", counter 6-2 need be resetted, the binary counting coding " 1111; 1010 " of described counter 6-2 output will low level " 0 " wherein be converted into behind the high level " 1 " by first by count resets not gate gating circuit 6-7 again and outputs to the reset terminal of counter 6-2 with a 6-3, make counter 6-2 zero clearing, restart counting, CPLD has just finished the work of setting clock period 2ms by internal logic circuit like this.The dutycycle of modulation signal is 2%, and promptly will make the pulse that is input to electrooptic modulator 2 is five continuous high level; If since 0 counting, the signal level that binary counting coding " 0～4 " these five pulses that counter 6-2 is exported output to electrooptic modulator all is a high level, through the result after Boolean calculation and the process simplification as can be seen, if make counting " 0～4 " output high level, as long as by modulation signal not gate gating circuit 6-1 low level " 0 " is wherein converted " 0000; 00xx " and " 0000; 0100 " two groups of signals to high level " 1 " through not gate, again two groups of signals are exported high level by two first with door 6-3 respectively, then with these two high level by first or five continuous high level of door 6-4 output, be the electrooptical modulation signal of 40ns through the first trigger 6-5 generation cycle again, clock signal of system is input to the trigger trigger end, electrooptical modulation Signals ﹠ Systems clock signal is kept synchronously, this embodiment is in order to increase the driving force of modulation signal, first or the outgoing side parallel connection of door 6-4 ten first trigger 6-5.
With one road signal is the generation of example explanation delay switch control signal.According to cycle of above-mentioned modulation signal is opening time (the fiber grating sensing signal pulse arrives the time delay of channel switch) of 40ns and used channel switch to determine the cycle of switch delay control signal and the opening time of switch.The unlatching of HF switch approximately needs the time of 10ns, so the opening time of switch is more Zao than transducing signal, for fear of the excessive generation overshoot when switch cuts out of signal pulse amplitude, the time outline that switch turn-offs is later than transducing signal, so the gating pulse of channel switch is slightly wideer than pulse signal level time, as shown in Figure 3, S0 is the time that the transducing signal of first sensing grating arrives the channel switch input end, S1 to S9 is second time to the transducing signal arrival channel switch input end of the tenth sensing grating, and K0 to K9 is the switch open control signal of ten grating sensing signal time division multiplex switches.This embodiment needs CPLD control circuit 6 to produce the switch delay control signal of 56ns, promptly needs to export the signal input end that channel switch 7 is given in seven continuous high level timesharing successively by a plurality of delay switch control signal generation circuit 6-6.Time from first optical grating reflection to electronic switch during this programme is implemented is 91.2ns, and the time of return of each grating is spaced apart 96.7ns.In first group of delay switch control signal generation circuit 6-6, arrive the time of electronic switch according to first sensing grating heat transfer agent, the sequential logic coding " 0000; 1011 " to " 0001; 0001 " of counter 6-2 output can be converted into high level " 1 " with low level " 0 " wherein by three not gate gating circuit 6-6-1, and export with door 6-6-2 by eight the tunnel second respectively, these three groups of level are again by second or seven continuous high level of door 6-6-3 output, this high level is converted into the synchronous signal of system clock by the second trigger 6-6-4 and is used to control the open-minded of first channel switch 7, make from the pulse information of first grating sensing 4-1 of unit reflected back thus Channel Transmission give transducing signal detecting device 8.Be depicted as from ten tunnel pulses of the grating sensing 4-1 of unit reflected back and boolean's brevity lists of delay control signal pulse as following table one.
Table one
| The reflected impulse sequence number | The reflected impulse sequential | Time-delay gating pulse sequential | The sequential logic coding | The |
| 1 | 91.2～131.2ns | 88～144ns | 0000，1011 | 0000，1011 |
| 0000，1100 | 0000，11×× | |||
| 0000，1101 | ||||
| 0000，1110 | ||||
| 0000，1111 | ||||
| 0001，0000 | 0001，000× | |||
| 0001，0001 | ||||
| 2 | 187.9～227.9ns | 184～240ns | 0001，0111 | 0001，0111 |
| 0001，1000 | 0001，10×× | |||
| 0001，1001 | ||||
| 0001，1010 | ||||
| 0001，1011 |
| 0001，1100 | 0001，110× | |||
| 0001，1101 | ||||
| ?3 | ?284.6～324.6ns | ?280～36ns | 0010，0011 | 0010，0011 |
| 0010，0100 | 0010，01×× | |||
| 0010，0101 | ||||
| 0010，0110 | ||||
| 0010，0111 | ||||
| 0010，1000 | 0010，100× | |||
| 0010，1001 | ||||
| 4 | 381.3～421.3ns | 376～432ns | 0010，1111 | 0010，1111 |
| 0011，0000 | 0011，00×× | |||
| 0011，0001 | ||||
| 0011，0010 | ||||
| 0011，0011 | ||||
| 0011，0100 0011，0101 | 0011，010× | |||
| 5 | 478～518ns | 472～528ns | 0011，1011 | 0011，1011 |
| 0011，1100 | 0011，11×× | |||
| 0011，1101 | ||||
| 0011，1110 | ||||
| 0011，1111 | ||||
| 0100，0000 | 0100，000× | |||
| 0100，0001 | ||||
| 6 | 574.7～614.7ns | 568～624ns | 0100，0111 | 0100，0111 |
| 0100，1000 | 0100，10×× | |||
| 0100，1001 | ||||
| 0100，1010 | ||||
| 0100，1011 | ||||
| 0100，1100 | 0100，110× | |||
| 0100，1101 | ||||
| 7 | 671.4～11.4ns | 664～720ns | 0101，0011 | 0101，0011 |
| 0101，0100 | 0101，01×× | |||
| 0101，0101 | ||||
| 0101，0110 | ||||
| 0101，0111 | ||||
| 0101，1000 | 0101，100× | |||
| 0101，1001 | ||||
| 8 | 768.1～808.1ns | 760～816ns | 0101，1111 | 0101，1111 |
| 0110，0000 | 0110，00×× | |||
| 0110，0001 | ||||
| 0110,0010 | ||||
| 0110，0011 | ||||
| 0110，0100 | 0110，010× |
| 0110，0101 | ||||
| ?9 | ?864.8～904.8ns | ?856～912ns | 0110，1011 | 0110，1011 |
| 0110，1100 | 0110，11×× | |||
| 0110，1101 | ||||
| 0110，1110 | ||||
| 0110，1111 | ||||
| 0111，0000 | 0111，000× | |||
| 0111，0001 | ||||
| 10 | 961.5～1001.5ns | 952～1008ns | 0111，0111 | 0111，0111 |
| 0111，1000 | 0111，10×× | |||
| 0111，1001 | ||||
| 0111，1010 | ||||
| 0111，1011 | ||||
| 0111，1100 | 0111，110× | |||
| 0111，1101 |
Monitoring with the nine road fiber grating sensing signal is an example, electrooptical modulation signal a, the electronic switch Continuity signal b of this embodiment and arrive electronic switch have sensing grating string heat transfer agent electronic impulse string c as shown in Figure 4.The shared clock signal of the generation of described electronic switch conducting control signal and modulation signal, make switching response synchronous at aspects such as frequency and dutycycle and light-pulse generator, can remove high frequency clock signal generator and chronotron from like this, reduce signal cross-talk, improved the signal to noise ratio (S/N ratio) and the cost performance of system.Other compositions and annexation thereof are identical with embodiment five.Adopt system of the present invention can arrive the resolution characteristic of 6ns.
Embodiment seven: referring to Fig. 1 to Fig. 2, this embodiment with the difference of embodiment one is: described channel switch 7 adopts low-loss InGaAs microwave high-frequency simulation SPDT switch, it comprises two control ends and two signal output parts, can realize two heat transfer agent transmission channels simultaneously.In embodiment five, only need to adopt five SPDT switches to get final product, two control ends of SPDT switch receive two switch delay control signals of CPLD control circuit 6 output terminals respectively, each signal output part of SPDT switch all connects a transducing signal detecting device 8, and the opening time of SPDT switch is approximately 10ns.Other compositions and annexation thereof are identical with embodiment one.
Claims (5)
1. based on the time division multiplex optical fiber grating sensing testing system of CPLD, it is characterized in that described system is by light source generator (1), electrooptic modulator (2), coupling mechanism (3), be serially connected with the optical fiber (4) of m grating sensing unit (4-1), CPLD control circuit (6), m channel switch (7), m transducing signal detecting device (8), photoelectric signal converter (5) and system clock circuit (9) are formed, the output terminal of light source generator (1) connects the light input end of electrooptic modulator (2), the light output end of electrooptic modulator (2) connects the input end of coupling mechanism (3), and the incident light that has grating sensing information of coupling mechanism (3) output is coupled in the optical fiber (4); The modulation signal output terminal of CPLD control circuit (6) connects the modulation signal input end of electrooptic modulator (2), the reflected light of coupling mechanism (3) output is input to the signal input part of m channel switch (7) by photoelectric signal converter (5), the signal output part of m channel switch (7) connects the input end of m transducing signal detecting device (8) respectively, m switch delay control signal output terminal of CPLD control circuit (6) connects the signal input end of m channel switch (7) respectively, and the output terminal of system clock circuit (9) connects the clock signal input terminal of CPLD control circuit (6); Described photoelectric signal converter (5) is used for the heat transfer agent of Wavelength-encoding is converted to the heat transfer agent of phase encoding, and wherein m is the natural number of non-zero.
2. the time division multiplex optical fiber grating sensing testing system based on CPLD according to claim 1, it is characterized in that described photoelectric signal converter (5) comprises the non-equilibrium michelson interferometer of full optical fiber (5-1), saw-toothed wave generator (5-2), amplifier (5-4), photodetector (5-3) and piezoelectric ceramics (5-5), the reflected light coupling with grating sensing information of coupling mechanism (3) output enters in the non-equilibrium michelson interferometer of full optical fiber (5-1), dilatation takes place in the driven piezoelectric ceramics (5-5) of saw-toothed wave generator (5-2) output, the flexible two ends of piezoelectric ceramics (5-5) are fixed on the arm of the non-equilibrium michelson interferometer of full optical fiber (5-1), the light signal of the complete non-equilibrium michelson interferometer of optical fiber (5-1) output is converted to electric signal by photodetector (5-3), and this electric signal is transferred to the signal input part of each channel switch (7) by amplifier (5-4).
3. the time division multiplex optical fiber grating sensing testing system based on CPLD according to claim 1, it is characterized in that described light source generator (1) comprises fibre optic isolater (1-1) and wideband light source (1-2), the output terminal of wideband light source (1-2) connects the input end of fibre optic isolater (1-1), and the output terminal of fibre optic isolater (1-1) connects the light input end of electrooptic modulator (2).
4. the time division multiplex optical fiber grating sensing testing system based on CPLD according to claim 1, it is characterized in that described each transducing signal detecting device (8) comprises bandpass filter (8-1) and phasometer (8-2), the input end of the signal output part connecting band bandpass filter (8-1) of channel switch (7), the output terminal of wave filter (8-1) connects the input end of phasometer (8-2).
5. the time division multiplex optical fiber grating sensing testing system based on CPLD according to claim 1, it is characterized in that described CPLD control circuit (6) by modulation signal not gate gating circuit (6-1), counter (6-2), first and door (6-3), second with door (6-8), first or door (6-4), count resets not gate gating circuit (6-7), at least one first trigger (6-5) and organize delay switch control signal generation circuit (6-6) more and form; The clock signal input terminal of the output terminal linkage counter (6-2) of system clock circuit (9) and the trigger end of all first triggers (6-5), the multidigit binary-coded information of counter (6-2) output by count resets not gate gating circuit (6-7) and second and (6-8) be input to the reset terminal of counter (6-2); The multidigit binary-coded information of counter (6-2) output successively by modulation signal not gate gating circuit (6-1), first with (6-3) and first or (6-4) after be input to the signal input part of all first triggers (6-5), the output terminal of all first triggers (6-5) all connects the modulation signal input end of electrooptic modulator (2); Each group delay switch control signal generation circuit (6-6) is by a plurality of not gate gating circuits (6-6-1), the a plurality of the 3rd with the door (6-6-2), second or door (6-6-3) and second trigger (6-6-4) composition, the output terminal of system clock circuit (9) connects the trigger end of all second triggers (6-6-4), in every group of delay switch control signal generation circuit (6-6), a plurality of output terminals of counter (6-2) connect the input end of a plurality of not gate gating circuits (6-6-1) respectively, the output terminal of each not gate gating circuit (6-6-1) is connected second or the input end of (6-6-3) by one the 3rd with door (6-6-2), second or the output terminal of door (6-6-3) connect the signal input part of second trigger (6-6-4), the output terminal of second trigger (6-6-4) connects the signal input end of a channel switch (7).
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