CN102412894A - Multifrequency probe light time division multiplexing coherent light time domain reflectometer method and apparatus thereof - Google Patents
Multifrequency probe light time division multiplexing coherent light time domain reflectometer method and apparatus thereof Download PDFInfo
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Abstract
The invention provides a method of a multifrequency probe light time division multiplexing coherent light time domain reflectometer. The method is characterized in that: a detection light pulse being injected into a fiber being detected is multifrequency detection light pulse which generates time division multiplexing by utilizing sequential electric signal synchronization control phase modulator and light pulse modulator modulation; local oscillator light is single-frequency light, and power spectrum of the multifrequency detection light pulse is bilaterally symmetrical relative to local oscillator light frequency; 0 order frequency of the multifrequency detection light pulse is same with the local oscillator light frequency; modulation depth of the phase modulator is larger than 1; a backward scattering and/or reflection signal which the multifrequency light pulse of time division multiplexing is in mixes with the local oscillator light in a coherent detection module, both side are coherent and an intermediate frequency signal of time division multiplexing is output by a photoelectric detector; an intermediate frequency signal processing module amplifies an intermediate frequency signal of time division multiplexing detected by coherent detection, according to a characteristic of the intermediate frequency signal, a needed band pass filter is selected, the intermediate frequency signal is filtered, a subsequent circuit carries out real-time processing on a plurality of paths of intermediate frequency signals, and information of the fiber being detected is displayed.
Description
Technical field:
The present invention relates to a kind of optical communication line that is used for optical fiber is characterized and fault location, amplify the coherent light time domain reflection appearance of submarine communication cable health monitoring in particular for long distance, many relayings.
Background technology:
At present, commercial coherent light time domain reflection (COTDR) appearance all uses the single mode narrow linewidth detecting optical pulses, and the signal of telecommunication that coherent detection produces is single intermediate-freuqncy signal, and the power through detecting this intermediate-freuqncy signal can obtain the health status of fibre circuit over time.Under specific pulsewidth condition, its dynamic range can promote through the average time that increases pulse peak power or increase data, but peak power receives the restriction of fiber nonlinear effect.Because the Photoelectric Signal Processing module of commercial system only is that an intermediate-freuqncy signal is handled, like this, for the monitoring of the optical cable communication line of growing distance, such as 12000 kilometers trans-oceanic extra large cable, the systematic survey time then can reach several hours.Because the COTDR system surveys light and uses the LASER Light Source of live width less than 10kHz, this flashlight that has just caused surveying between the Rayleigh scattering unit of light in tested optical fiber has extremely strong coherence, thereby causes relevant rayleigh noise.Relevant rayleigh noise can cause the big ups and downs of detective curve, thereby influence is to the identification of optical communication line case point.For eliminating relevant rayleigh noise and increasing the dynamic range of measuring, the most frequently used way is exactly to increase to measure and average number of times, and the detective curve of COTDR generally is 2
16Inferior measurement result average reaches 2 sometimes
18Inferior or higher.
The performance evaluation of COTDR has three important parameters: dynamic range, spatial resolution and Measuring Time.Mainly detection of optical power is measured with increase and average number of times is realized through promoting in the lifting of dynamic range.But because the particularly restriction of stimulated Brillouin scattering of nonlinear effect in the optical fiber, the detection of optical power that incides in the tested optical fiber should be lower than the excited Brillouin threshold value, so the lifting of system dynamics scope is restricted.Measurement spatial resolution mainly receives the restriction of detecting optical pulses width, shortens the detecting optical pulses width with room for promotion resolution, but can reduce the dynamic range of measurement.Through the mode of pulse code, can make measurement have big dynamic range and high spatial resolution simultaneously, but this can increase the time that system signal is handled sharp.In view of above-mentioned many restrictions, we the key that promotes the COTDR systematic function be placed on increase measure and average number of times on.Obviously, commercial at present increase measurement of COTDR system and average time can only be realized by increasing the time of measuring.Wanting is not the measurement effect that cost obtains to sacrifice Measuring Time, and only way is the measuring speed of elevator system.
The research Japan NTT Masatoyo Sumida of company about promoting COTDR systematic survey speed had the experiment report in 1996.It is to utilize the injection current of control distributed Blatt reflective formula (DBR) laser to change the detection light frequency, obtains the detecting optical pulses sequence of different frequency through SECO.Survey light and be essentially frequency pulse, just detection of optical power be constant and the time continuous, but its frequency then is time-discrete.Survey backscattering and/or the reflected signal and the local oscillator light of single-frequency relevant generation a plurality of different intermediate-freuqncy signals of light frequency pulse in tested optical fiber; The corresponding drive test amount of intermediate-freuqncy signal; The corresponding curve of multichannel intermediate-freuqncy signal finally synthesizes one the tunnel, and measuring speed is multiplied.So, the Photoelectric Signal Processing module of this scheme, behind a plurality of bandpass filterings, the parallel processing data, and then synthesize one road signal output through accumulator.Experimental result shows that this method can reduce the decline noise of detective curve apace, promotes signal to noise ratio.But this method is surveyed light, and constantly can only there be a frequency in each, and to the extra circuit design of control needs of laser, the controlled-precision system circuit hardware of control and the Effect on Performance of laser own are very big.In addition, the local oscillator light of this scheme appears at the last of a pulse train cycle, therefore, certainly leads to the blind area of bringing because of the design defective.
Summary of the invention:
The present invention seeks to propose multifrequency and survey Optical Time Division Multiplexing coherent light time domain reflection appearance method and apparatus; Especially the decline noise that proposes to reduce quickly detective curve with promote the dynamic range of measuring, and the multifrequency that improves greatly of measuring speed is surveyed the method and apparatus of Optical Time Division Multiplexing coherent light time domain reflection appearance.Said technical scheme is following:
Multifrequency is surveyed the method for Optical Time Division Multiplexing coherent light time domain reflection appearance; The detecting optical pulses that is injected in the tested optical fiber is time-multiplexed multifrequency detecting optical pulses, can utilize sequential signal of telecommunication Synchronization Control phase-modulator and light pulse modulators modulate to produce time-multiplexed multifrequency detecting optical pulses; Local oscillator light is single-frequency laser, and the power spectrum of multifrequency detecting optical pulses is symmetrical with respect to local oscillator light frequency both sides; Utilize 0 order frequency of the time-multiplexed multifrequency detecting optical pulses that sequential signal of telecommunication Synchronization Control phase-modulator and light pulse modulator produce identical with the local oscillator light frequency; The modulation depth of phase-modulator is greater than 1; Time-multiplexed multifrequency light pulse backscattering and/or reflected signal mix in the coherent detection module with local oscillator light, the two phase dry doubling is exported time-multiplexed intermediate-freuqncy signal by photodetector; The intermediate-freuqncy signal processing module is amplified the time-multiplexed intermediate-freuqncy signal that coherent detection obtains, and according to the characteristic of intermediate-freuqncy signal, selects required band pass filter, leaches intermediate-freuqncy signal, and subsequent conditioning circuit is handled the multichannel intermediate-freuqncy signal in real time, shows tested optical fiber information; Or the method for directly using Digital Signal Processing is extracted the power of intermediate-freuqncy signal and is done the sequential alignment, demonstration tested optical fiber detective curve.
To the processing of time-multiplexed intermediate-freuqncy signal, can realize through hardware circuit; Treatment step comprises the amplification intermediate-freuqncy signal; Deliver to each filter unit again and leach each intermediate-freuqncy signal; Respectively each intermediate frequency is being carried out analog-to-digital conversion, Digital Down Convert and extracting intermediate-freuqncy signal power then; Then the power to each intermediate-freuqncy signal carries out the sequential alignment, superposes, asks average again, shows detective curve at last.
To the processing of time-multiplexed intermediate-freuqncy signal, can realize through software approach; Treatment step comprises and utilizes data collecting card to gather intermediate-freuqncy signal; Again the data of gathering are done digital band pass filtering and leach each intermediate-freuqncy signal; Respectively each intermediate frequency is being carried out Digital Down Convert and LPF to extract each intermediate-freuqncy signal power then; Then the power to each intermediate-freuqncy signal carries out the sequential alignment, superposes, asks average again, shows detective curve at last.It is 2.405 that the driving voltage of phase-modulator makes its modulation depth
A kind of multifrequency is surveyed the device of Optical Time Division Multiplexing coherent light time domain reflection appearance, and said device comprises:
Light source module, light source are provided with two-way output, and one the road surveys optical module to multifrequency, and one the tunnel is single-frequency local oscillator light;
Multifrequency is surveyed optical module, connects light source module, utilizes signal of telecommunication while control phase modulator and light pulse modulator with sequential organization, thereby produces time division multiplexing multifrequency detecting optical pulses;
The coherent detection module; Backscattering and/or reflected signal that multifrequency detection optical module outputs to tested optical fiber mix in the coherent detection module with single-frequency local oscillator light; Realization to the multifrequency detecting optical pulses in tested optical fiber with the coherent detection of local oscillator light, thereby obtain time-multiplexed a plurality of intermediate-freuqncy signal output;
The intermediate-freuqncy signal processing module connects and also to amplify coherent detection module intermediate-freuqncy signal, and the characteristics of the intermediate-freuqncy signal that obtains according to coherent detection again leach required intermediate-freuqncy signal, handle intermediate-freuqncy signal and show the information relevant with tested optical fiber.
Multifrequency is surveyed in the optical module; The signal of telecommunication with sequential organization changes the modulating frequency of phase-modulator chronologically; And the generation of Synchronization Control light pulse modulator pulses, the time division multiplexing detecting optical pulses sequence that the light pulse modulator was exported in the same pulse period produces under out of phase modulators modulate frequency;
In the light source module, single-frequency laser is divided into two-way through coupler, and one the tunnel gets into phase-modulator, produces multifrequency through the phase-modulator modulation and surveys light, and one the tunnel is used as single-frequency local oscillator light;
Multifrequency is surveyed in the optical module, and the light pulse modulator is selected electrooptic modulator for use, and by the pulse electrical signal control with sequential organization;
In the light source module, single-frequency laser is divided into two-way through coupler, and one the tunnel gets into phase-modulator, produces multifrequency through the phase-modulator modulation and surveys light, and one the tunnel is used as single-frequency local oscillator light;
Multifrequency is surveyed in the optical module, and the light pulse modulator is selected acousto-optic modulator for use, and by the pulse electrical signal control with sequential organization;
In the coherent detection module, select acousto-optic modulator for use in the local oscillator light light path, and make it be operated in continuous mode with identical shift frequency effect;
In the intermediate-freuqncy signal processing module; Intermediate-freuqncy signal is handled and can be used software approach to realize; Detailed process comprises successively: data acquisition, digital band pass filtering, Digital Down Convert and LPF, and signal sequence is adjusted, signal power summation and average, shows detective curve at last;
In the intermediate-freuqncy signal processing module, intermediate-freuqncy signal is handled the timely ordered pair of extraction that can use analog filter group and hardware circuit to realize intermediate-freuqncy signal power and is answered, and shows detective curve at last.
The invention has the beneficial effects as follows: compare with the coherent light time domain reflection appearance based on single-frequency detection light of commercialization, the present invention can reduce the decline noise and the dynamic range that promotes measurement of detective curve quickly, and measuring speed improves greatly.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the present invention is further specified.
Fig. 1 is a kind of method sketch map that the multifrequency that the present invention relates to is surveyed Optical Time Division Multiplexing coherent light time domain reflection appearance.
Fig. 2 is that the multifrequency that the present invention relates to is surveyed the method sketch map that Optical Time Division Multiplexing coherent light time domain reflection appearance time division multiplexing multifrequency detecting optical pulses produces.
Fig. 3 is that the multifrequency that the present invention relates to is surveyed interior time division multiplexing multifrequency detecting optical pulses sketch map of pulse period of Optical Time Division Multiplexing coherent light time domain reflection appearance.
Fig. 4 is the multifrequency detection of optical power spectrum sketch map that the multifrequency that the present invention relates to is surveyed a certain moment output of Optical Time Division Multiplexing coherent light time domain reflection appearance phase-modulator.
Fig. 5 is that the multifrequency that the present invention relates to is surveyed a kind of structure chart of Optical Time Division Multiplexing coherent light time domain reflection instrument apparatus.
Fig. 6 is backscattering and/or reflected signal and the single-frequency local oscillator light relevant sketch map that produce intermediate-freuqncy signal of time division multiplexing detecting optical pulses in tested optical fiber.
Fig. 7 is a kind of structure chart based on software engineering that the multifrequency that the present invention relates to is surveyed Optical Time Division Multiplexing coherent light time domain reflection appearance intermediate-freuqncy signal processing module.
Fig. 8 be multifrequency involved in the present invention survey Optical Time Division Multiplexing coherent light time domain reflection appearance intermediate-freuqncy signal processing module based on a kind of structure chart of hardware technology.
Fig. 9 is the corresponding detective curve of time-multiplexed each intermediate-freuqncy signal that the present invention relates to and the detective curve sketch map of final gained.
Figure 10 is the sketch map that filling light of the present invention and time-multiplexed detecting optical pulses sequence form accurate continuous light.
Figure 11 is that the present invention's structure shown in Figure 5 is used the sketch map of filling light and the accurate continuous light of the complementary formation of detecting optical pulses.
Figure 12 adopts acousto-optic modulator to produce a kind of sketch map of detecting optical pulses in the present invention's structure shown in Figure 5.
1. single-frequency laser light sources among the figure; 2. beam splitter; 3. phase-modulator; 4. image intensifer; 5. light pulse modulator; 6. circulator; 7. scrambler; 8. optical interface; 9.X type three-dB coupler; 10. photodetector; 11. electric amplifier; 12. multichannel band pass filter group; 13. data acquisition unit; 14. Digital Down Convert unit; 15. low-pass filter unit; 16. intermediate-freuqncy signal is synthetic and real unit; 17. filling radiant; 18. acousto-optic modulator; 19. wavelength division multiplexer; 101. light source module; 102. time division multiplexing is surveyed optical module; 103. coherent detection module; 104. intermediate-freuqncy signal processing module; 200. single-frequency light source; 201. time division multiplexing multifrequency detecting optical pulses; 202. backscattering and/or reflected signal; 203. coherent detection; 204. intermediate-freuqncy signal is handled.
Embodiment
See Fig. 1, a kind of multifrequency that the embodiment of the invention provides is surveyed the method for Optical Time Division Multiplexing coherent light time domain reflection appearance, and this method detailed content is following:
200: the laser that the single-frequency laser light source sends is divided into two-way through beam splitter, and one the tunnel through phase-modulator modulation generation multifrequency light, and another road is used as single-frequency local oscillator light;
201: the modulation depth of phase-modulator is utilized sequential signal of telecommunication Synchronization Control phase-modulator and light pulse modulator greater than 1, produces the time division multiplexing detecting optical pulses; The control procedure of the sequential signal of telecommunication is as shown in Figure 2; The radio-frequency driven of phase-modulator produces the frequency pulse of sequential organization under the triggering of the sequential signal of telecommunication; As shown in Figure 3; This frequency pulse drives phase modulated and goes output device to have the multifrequency of sequential organization to survey light, and simultaneously, the sequential signal of telecommunication drives optical pulse generator and produces the multifrequency detecting optical pulses.The multifrequency detecting optical pulses is at certain frequency pulse f
iThe power spectrum that drives the multifrequency detecting optical pulses that produces down is as shown in Figure 4.
202: collect backscattering and/or the reflected signal of time-multiplexed multifrequency detecting optical pulses in tested optical fiber;
203: backscattering and/or the reflected signal of time-multiplexed multifrequency detecting optical pulses in tested optical fiber and local oscillator light produce a plurality of relevant intermediate-freuqncy signals, and are received by photodetector through mixing;
204: amplify relevant intermediate-freuqncy signal, leach each intermediate-freuqncy signal again, the characteristic of intermediate-freuqncy signal is as shown in Figure 6; Handle these intermediate-freuqncy signals in real time and synthesize one the tunnel, show detective curve at last, this process is as shown in Figure 9.
See Fig. 5, the method and apparatus that the embodiment of the invention provides a kind of multifrequency to survey light coherent light time domain reflection appearance, this method and device detailed content are following:
The light that single-frequency laser light source 1 sends is divided into two bundles through 90: 10 beam splitter 2; One termination of high power output goes into to survey the light light path; It is 2.405 that the driving voltage that phase-modulator 3 is set makes its modulation depth; The power of 0 order frequency from the power spectrum of phase-modulator 3 output multifrequency light is minimum like this, and most power concentration is on ± 1 rank and ± 2 order frequencies, and its power spectrum structure is as shown in Figure 4;
The multifrequency of phase-modulator 3 outputs is surveyed light again through image intensifer 4, amplifies the power of surveying light to promote like erbium-doped fiber amplifier, becomes detecting optical pulses through electrooptic modulator 5 again;
Phase-modulator 3 is controlled by the sequential signal of telecommunication with electrooptic modulator 5.As producing the sequential signal of telecommunication with pulse signal generator; The meaning waveform generator is taken in the triggering of pulse signal generator; Make AWG produce the time division multiplexing structure frequency pulse that has as shown in Figure 3, export time-multiplexed multifrequency and survey light to drive phase-modulator.Phase-modulator is at driving frequency f
iThe power spectrum of the multifrequency detection light of following output is as shown in Figure 4.In addition, the electric impulse signal of pulse signal generator output drives electrooptic modulator 5, to produce time-multiplexed multifrequency detecting optical pulses;
The local oscillator light frequency is identical with 0 order frequency of multifrequency detecting optical pulses; Backscattering and/or the reflected signal of some like this multifrequency detecting optical pulses in tested optical fiber ± 1 rank are concerned with local oscillator light with ± 2 order frequencies and only produce two intermediate-freuqncy signals, and are as shown in Figure 6.Because detecting optical pulses is time-multiplexed, then it will produce time-multiplexed a plurality of intermediate-freuqncy signal.
Detecting optical pulses through scrambler disturb 6 partially after, inject tested optical fiber through circulator 7 with through optical interface 8 again;
The dorsad Rayleigh scattering light of detecting optical pulses in tested optical fiber mixes with the X-coupler 9 of single-frequency local oscillator light at 3dB, the two relevant a plurality of intermediate-freuqncy signal that produce with sequential organization, and from photodetector 10 outputs;
Real-time processing to intermediate-freuqncy signal can be used software approach; As shown in Figure 7; Intermediate-freuqncy signal is after electric amplifier 11 amplifies; Leach most of out-of-band noise by multichannel band pass filter, the bandwidth of filter is not less than the inverse of detecting optical pulses width, then gathers the signal of telecommunication by data collecting card and is used as Digital Signal Processing;
Digital signal processing comprises and utilizes multichannel digital band-pass filter group to leach and time-multiplexed each road intermediate-freuqncy signal; Then carry out Digital Down Convert and LPF to extract the power of intermediate-freuqncy signal; At last through the sequential adjustment; Summation and average calculating operation obtain final detective curve, and this process is as shown in Figure 9.
Can use hardware approach to realize to the real-time processing of intermediate-freuqncy signal; As shown in Figure 8; The intermediate-freuqncy signal of photodetector 10 outputs; After electric amplifier 11 amplifies, be transported to each hardware handles unit, realize that through hardware circuit filtering, analog-to-digital conversion, Digital Down Convert, LPF and sequential modulation and data summation with average, show detective curve at last.
Light source module of the present invention provides initial light source for surveying light, and also for the coherent detection module provides local oscillator light, light source module is selected single frequency laser for use;
Time division multiplexing is surveyed optical module, connects light source module, the multifrequency detecting optical pulses that utilizes sequential signal of telecommunication Synchronization Control phase-modulator and light pulse modulator to have sequential organization with generation, promptly time-multiplexed multifrequency detecting optical pulses;
The coherent detection module connects light source module and time division multiplexing and surveys optical module, and backscattering and/or the reflected signal of time-multiplexed detecting optical pulses in tested optical fiber mixed with local oscillator light, the time-multiplexed intermediate-freuqncy signal of the two relevant generation;
The intermediate-freuqncy signal processing module; Connect the coherent detection module; The time-multiplexed intermediate-freuqncy signal that amplification is exported from the coherent detection module utilizes a plurality of filters to realize the separation to a plurality of intermediate-freuqncy signals, then in each intermediate-freuqncy signal of parallel processing; Obtain detective curve at last and show that also can utilize Digital Signal Processing is that software approach is realized this process.
Wherein, described device also comprises: time division multiplexing is surveyed optical module, after the time division multiplexing detecting optical pulses has sent, sends and fills light pulse, makes the two take the whole pulse period, promptly forms accurate continuous light.
See Figure 12, the another kind of multifrequency that the embodiment of the invention provides is surveyed the device of light coherent light time domain reflection appearance, and this device is basic identical with embodiment 2 structures, and just, the light pulse modulator uses acousto-optic modulator 18 in the system.Because acousto-optic modulator 18 has the shift frequency effect; Therefore; In coherent detection module local oscillator light light path, also use a acousto-optic modulator 18 with identical frequency shift property; But it works again, and the continuous light pattern only plays the shift frequency effect, so 0 order frequency in the multifrequency detecting optical pulses is identical with the local oscillator light frequency.So just can guarantee that result as shown in Figure 6 appears in relevant intermediate-freuqncy signal.
Embodiment 4
The single-frequency laser that external cavity semiconductor laser 1 sends is divided into two bundles through 90: 10 beam splitter 2, and high-power a branch of connection phase-modulator 3 is used to produce multifrequency and surveys light, and is lower powered a branch of as local oscillator light, connects an end of the three-dB coupler 9 of X type.Utilize pulse signal generator to produce the sequential signal of telecommunication.The trigger end of pulse signal generator is taken over the meaning waveform generator, and the sequential of the radiofrequency signal of AWG output is set, and makes it under the triggering level effect, produce the frequency pulse with sequential organization, thereby drives phase-modulator 3.The pulse duration of frequency pulse is 1 microsecond; Frequency is followed successively by 15MHZ, 16MHz, 17MHz, 18MHz, 19MHz; Totally 5. simultaneously; Utilizing pulse signal generator to produce pulsewidth is cycle of 1 microsecond to be 1.2 milliseconds electric pulse, and to produce pulsewidths be to be 1.2 milliseconds light pulse in 1 microsecond cycle to drive electrooptic modulator 5.The time-multiplexed multifrequency of phase-modulator 3 outputs is surveyed light and is amplified by erbium-doped fiber amplifier 4.
Detecting optical pulses is injected in 100 kilometers long tested optical fiber through circulator 7 with through optical interface 8 after scrambler 6 is disturbed partially again;
The dorsad Rayleigh scattering light of detecting optical pulses in tested optical fiber mixes with the X-coupler 9 of single-frequency local oscillator light at 3dB, the two relevant a plurality of intermediate-freuqncy signal that produce with sequential organization, and by photodetector 10 receptions; Relevant process produces 10 intermediate-freuqncy signals, and their frequency is respectively 15MHz, 30MHz, 16MHz, 32MHz, 17MHz, 34MHz, 18MHz, 36MHz, 19MHz, 38MHz.
This 10 tunnel intermediate-freuqncy signal from photodetector 10 outputs; After electric amplifier 11 amplifies; Deliver to each signal processing unit more respectively; Respectively this 10 tunnel intermediate-freuqncy signal is carried out bandpass filtering, Digital Down Convert and LPF accomplishing the extraction of many each road intermediate-freuqncy signal power, thereby obtain detective curve, as shown in Figure 9.Wherein, the bandwidth of band pass filter 12 should be not less than the inverse of detecting optical pulses width, and for the detecting optical pulses width of 1 microsecond, the bandwidth of band pass filter can be taken as 1MHz.Because intermediate-freuqncy signal also is time-multiplexed, therefore need carries out summation and average again after the sequential alignment, thereby obtain final detective curve the data of the corresponding detective curve of each road intermediate-freuqncy signal.
Claims (10)
1. multifrequency is surveyed the method for Optical Time Division Multiplexing coherent light time domain reflection appearance; The detecting optical pulses that it is characterized in that being injected in the tested optical fiber is time-multiplexed multifrequency detecting optical pulses, utilizes sequential signal of telecommunication Synchronization Control phase-modulator and light pulse modulators modulate to produce time-multiplexed multifrequency detecting optical pulses; Local oscillator light is single-frequency laser, and the power spectrum of multifrequency detecting optical pulses is symmetrical with respect to local oscillator light frequency both sides; Utilize 0 order frequency of the time-multiplexed multifrequency detecting optical pulses that sequential signal of telecommunication Synchronization Control phase-modulator and light pulse modulator produce identical with the local oscillator light frequency; The modulation depth of phase-modulator is greater than 1; Time-multiplexed multifrequency light pulse backscattering and/or reflected signal mix in the coherent detection module with local oscillator light, the two phase dry doubling is exported time-multiplexed intermediate-freuqncy signal by photodetector; The intermediate-freuqncy signal processing module is amplified the time-multiplexed intermediate-freuqncy signal that coherent detection obtains, and according to the characteristic of intermediate-freuqncy signal, selects required band pass filter, leaches intermediate-freuqncy signal, and subsequent conditioning circuit is handled the multichannel intermediate-freuqncy signal in real time, shows tested optical fiber information; Or the method for directly using Digital Signal Processing is extracted the power of intermediate-freuqncy signal and is done the sequential alignment, demonstration tested optical fiber detective curve.
2. multifrequency according to claim 1 is surveyed the method for Optical Time Division Multiplexing coherent light time domain reflection appearance, it is characterized in that the processing to time-multiplexed intermediate-freuqncy signal, can realize through hardware circuit; Treatment step comprises the amplification intermediate-freuqncy signal; Deliver to each filter unit again and leach each intermediate-freuqncy signal; Respectively each intermediate frequency is being carried out analog-to-digital conversion, Digital Down Convert and extracting intermediate-freuqncy signal power then; Then the power to each intermediate-freuqncy signal carries out the sequential alignment, superposes, asks average again, shows detective curve at last.
3. multifrequency according to claim 1 and 2 is surveyed the method for Optical Time Division Multiplexing coherent light time domain reflection appearance, it is characterized in that the processing to time-multiplexed intermediate-freuqncy signal, realizes through software approach; Treatment step comprises and utilizes data collecting card to gather intermediate-freuqncy signal; Again the data of gathering are done digital band pass filtering and leach each intermediate-freuqncy signal; Respectively each intermediate frequency is being carried out Digital Down Convert and LPF to extract each intermediate-freuqncy signal power then; Then the power to each intermediate-freuqncy signal carries out the sequential alignment, superposes, asks average again, shows detective curve at last.
4. multifrequency according to claim 1 and 2 is surveyed the method for Optical Time Division Multiplexing coherent light time domain reflection appearance, and it is 2.405 that the driving voltage that it is characterized in that phase-modulator makes its modulation depth.
5. a multifrequency is surveyed the device of Optical Time Division Multiplexing coherent light time domain reflection appearance, and said device comprises:
Light source module, light source are provided with two-way output, and one the road surveys optical module to multifrequency, and one the tunnel is single-frequency local oscillator light;
Multifrequency is surveyed optical module, connects light source module, utilizes signal of telecommunication while control phase modulator and light pulse modulator with sequential organization, thereby produces time division multiplexing multifrequency detecting optical pulses;
The coherent detection module; Backscattering and/or reflected signal that multifrequency detection optical module outputs to tested optical fiber mix in the coherent detection module with single-frequency local oscillator light; Realization to the multifrequency detecting optical pulses in tested optical fiber with the coherent detection of local oscillator light, thereby obtain time-multiplexed a plurality of intermediate-freuqncy signal output;
The intermediate-freuqncy signal processing module connects and also to amplify coherent detection module intermediate-freuqncy signal, and the characteristics of the intermediate-freuqncy signal that obtains according to coherent detection again leach required intermediate-freuqncy signal, handle intermediate-freuqncy signal and show the information relevant with tested optical fiber.
Multifrequency is surveyed in the optical module; The signal of telecommunication with sequential organization changes the modulating frequency of phase-modulator chronologically; And the generation of Synchronization Control light pulse modulator pulses, the time division multiplexing detecting optical pulses sequence that the light pulse modulator was exported in the same pulse period produces under out of phase modulators modulate frequency;
In the light source module, single-frequency laser is divided into two-way through coupler, and one the tunnel gets into phase-modulator, produces multifrequency through the phase-modulator modulation and surveys light, and one the tunnel is used as single-frequency local oscillator light;
Multifrequency is surveyed in the optical module, and the light pulse modulator is selected electrooptic modulator for use, and by the pulse electrical signal control with sequential organization;
In the light source module, single-frequency laser is divided into two-way through coupler, and one the tunnel gets into phase-modulator, produces multifrequency through the phase-modulator modulation and surveys light, and one the tunnel is used as single-frequency local oscillator light;
Multifrequency is surveyed in the optical module, and the light pulse modulator is selected acousto-optic modulator for use, and by the pulse electrical signal control with sequential organization;
In the coherent detection module, select acousto-optic modulator for use in the local oscillator light light path, and make it be operated in continuous mode with identical shift frequency effect;
In the intermediate-freuqncy signal processing module; Intermediate-freuqncy signal is handled and can be used software approach to realize; Detailed process comprises successively: data acquisition, digital band pass filtering, Digital Down Convert and LPF, and signal sequence is adjusted, signal power summation and average, shows detective curve at last; The timely ordered pair of extraction of intermediate-freuqncy signal processing module or use analog filter group and hardware circuit realization intermediate-freuqncy signal power is answered, and shows detective curve at last.
6. multifrequency according to claim 5 is surveyed the device of Optical Time Division Multiplexing coherent light time domain reflection appearance; It is characterized in that; Said multifrequency is surveyed in the optical module; The signal of telecommunication with sequential organization changes the modulating frequency of phase-modulator chronologically, and the generation of Synchronization Control light pulse modulator pulses, and the time division multiplexing detecting optical pulses sequence that the light pulse modulator was exported in the same pulse period produces under out of phase modulators modulate frequency.
7. according to the device of claim 5 or 6 described multifrequencies detection Optical Time Division Multiplexing coherent light time domain reflection appearance, it is characterized in that,
Multifrequency is surveyed in the optical module, and the light pulse modulator is selected electrooptic modulator for use, and by the pulse electrical signal control with sequential organization.
8. multifrequency according to claim 5 is surveyed the device of Optical Time Division Multiplexing coherent light time domain reflection appearance; It is characterized in that; In the said light source module, single-frequency laser is divided into two-way through coupler, and one the tunnel gets into phase-modulator; Produce multifrequency through the phase-modulator modulation and survey light, the one tunnel is used as single-frequency local oscillator light; Multifrequency is surveyed in the optical module, and the light pulse modulator is selected acousto-optic modulator for use, and by the pulse electrical signal control with sequential organization; In the coherent detection module, select acousto-optic modulator for use in the local oscillator light light path, and make it be operated in continuous mode with identical shift frequency effect.
9. multifrequency according to claim 5 is surveyed the device of Optical Time Division Multiplexing coherent light time domain reflection appearance; It is characterized in that; In the said intermediate-freuqncy signal processing module, intermediate-freuqncy signal is handled and is used software approach to realize that detailed process comprises successively: data acquisition, digital band pass filtering, Digital Down Convert and LPF; And signal sequence is adjusted, signal power summation and average, shows detective curve at last.
10. multifrequency according to claim 5 is surveyed the device of Optical Time Division Multiplexing coherent light time domain reflection appearance; It is characterized in that; In the said intermediate-freuqncy signal processing module; Intermediate-freuqncy signal is handled the timely ordered pair of extraction that can use analog filter group and hardware circuit to realize intermediate-freuqncy signal power and is answered, and shows detective curve at last.
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| CN102645268A (en) * | 2012-04-26 | 2012-08-22 | 中国科学院上海光学精密机械研究所 | Optical frequency division multiplexing phase-sensitive optical time domain reflectometer |
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