CN2788167Y - Optical impulse receiving and processing device for optical time domain reflect meter - Google Patents
Optical impulse receiving and processing device for optical time domain reflect meter Download PDFInfo
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- CN2788167Y CN2788167Y CNU2005200813592U CN200520081359U CN2788167Y CN 2788167 Y CN2788167 Y CN 2788167Y CN U2005200813592 U CNU2005200813592 U CN U2005200813592U CN 200520081359 U CN200520081359 U CN 200520081359U CN 2788167 Y CN2788167 Y CN 2788167Y
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- time domain
- operational amplifier
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- optical time
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Abstract
The utility model relates to an optical impulse receiving and processing device for an optical time domain reflect meter, which belongs to the field of measuring devices. The utility model comprises a light receiver B1 and an A/D converter. The utility model is characterized in that the light receiver B1 is connected with the A/D converter though a current and voltage converter, an adjustable gain amplifier, a fixed gain amplifier, a filtering controller and a filtering network. The optical impulse receiving and processing device for an optical time domain reflect meter has the advantages that the device can adjust amplification factors of detecting signals as required, adjust bandwidth of the device and reduce detecting blind zones of the device. The utility model also has the advantages of large dynamic range of collecting signals and low noise.
Description
Technical field
The utility model relates to a kind of reception, treating apparatus of optical time domain reflectometer light pulse, belongs to the surveying instrument field.
Background technology
Optical time domain reflectometer (OPTICAL TIME DOMAIN REFLECTOMETER is called for short OTDR) is intelligentized optical fiber communication surveying instrument.The loss distribution curve that can accurately show optical fiber cable, attenuation coefficient that can the measuring optical fiber optical cable, point-to-point transmission loss and splicing loss, length that also can the measuring optical fiber optical cable, distance between two points is determined the position of joint, trouble spot and the breakpoint of optical fiber cable.Optical time domain reflectometer is to design according to the propagation characteristic of light in optical fiber.When Optical Fiber Transmission is passed through in light pulse, all can cause Rayleigh scattering along the every bit on the fiber lengths, this scattering to all the winds, wherein total some meeting is along the fiber axis reverse transfer to input end, this phenomenon is called backscattering, gather backscatter signals and can know the attenuation characteristic of optical fiber, i.e. the loss information of optical fiber.When entering in the medium of different refractivity, light can produce Fresnel reflection.For example in the optical fiber connector surface, all can produce this reflection a cracks.The meaning of gathering the Fresnel reflection signal is: if fault has taken place optical cable, Fresnel reflection can reflect breakpoint location, ensures that communication recovers rapidly; Utilize this characteristic can also extrapolate the length of optical cable, determine joint location and measure the optical cable meaning distance between two points of taking up an official post, the daily servicing of optical cable and fault are got rid of all extremely important meaning.When light pulse was propagated in optical fiber, these two kinds of phenomenons all can take place.Optical time domain reflectometer is exactly with powerful laser pulse, is injected in the optical fiber, detects along optical fiber back light signal dorsad at same end then, has both comprised the return signal of Rayleigh scattering in the tested light signal, comprises the signal that Fresnel reflection produces again.
Optical time domain reflectometer generally is made up of following components: microprocessor, light pulse transmitter, light pulse reception, processor, part of data acquisition, display part and peripheral logical circuit.Wherein light pulse reception, processor are the most essential parts of whole instrument, and they are representing the core technology of optical time domain reflectometer.Aspect the reception of light pulse, processing, there is following problem in traditional optical time domain reflectometer.
(1) because the Fresnel reflection signal is stronger, can make current-to-voltage convertor saturated, saturatedly need the long period from being saturated to withdraw from, during this period of time within, useful light signal can't be gathered; And have stronger ring at the pulse edge place.
(2) the Strength Changes scope of light signal is very big, and this just requires instrument can handle strong signal, can handle utmost point weak signal again, and the general stepping of traditional optical time domain reflectometer amplifies, and enlargement factor can not be adjustable continuously.
(3) in reality test, the needed bandwidth of system is not changeless, but the bandwidth that instrument provides but fix, this must lose the useful signal of a part, finally influences the blind area index of instrument.
The utility model content
The technical problems to be solved in the utility model is: provide a kind of and can need regulate bandwidth and signal amplification factor according to the user, effectively reception, the treating apparatus of the optical time domain reflectometer light pulse of pickoff signals and elimination ring.
The technical scheme that its technical matters that solves the utility model adopts is: the reception of this optical time domain reflectometer light pulse, treating apparatus, comprise optical receiver B1, A/D converter, it is characterized in that: optical receiver B1 links to each other with A/D converter by current-to-voltage convertor, variable gain amplifier, fixed gain amplifier, filter controller, filter network.The light pulse transmitter is linked testing fiber by fiber coupler, and light pulse reception, processor receive and handle the signal that returns from testing fiber by fiber coupler.Principle of work is the different light signals of optical receiver B1 according to reception, produces the electric current that is proportional to light signal.Current signal changes into positive voltage signal through current-to-voltage convertor, and the amplification by variable gain amplifier and fixed gain amplifier becomes the intensity that A/D converter can be changed fully then.Through the signal after amplifying, remove the noise that each link produces by the filter action of filter network, make the signal that finally enters A/D converter reflect measured signal truly.
Current-to-voltage convertor comprises operational amplifier N1, diode V1 and resistance R 1, is connected to diode V1 and resistance R 1 between the inverting input of operational amplifier N1 and the output terminal.Output voltage is proportional to the current value of input.
Fixed gain amplifier comprises operational amplifier N3, resistance R 2-R4, the inverting input of resistance R 2, a R3 termination operational amplifier N3 in parallel, and resistance R 4 is attempted by inverting input and the output terminal of operational amplifier N3.Conditioning signal intensity as required.
Variable gain amplifier comprises operational amplifier N2, potentiometer RP1, the G1 pin of operational amplifier N2 connects the sliding contact of potentiometer RP1, the G2 pin connects+end of 1.2V voltage and potentiometer RP1, and the other end ground connection of potentiometer RP1, the com pin ground connection of operational amplifier N2.Signal is adjusted to certain amplitude makes A/D converter to change fully.
Filter network comprises one or more different wave filters.
Filter controller comprises one or more relay contacts, and the contact links to each other with wave filter.
Compared with prior art, the reception of this optical time domain reflectometer light pulse, the beneficial effect that treating apparatus had are: this device can be regulated the enlargement factor of detection signal as required, can regulate the bandwidth of instrument, reduce the detection blind area of instrument, and it is big to have the acquired signal dynamic range, the characteristics that noise is little, the range performance of measuring optical fiber and attenuation characteristic preferably.
Description of drawings
Fig. 1 is reception, the treating apparatus circuit block diagram of optical time domain reflectometer light pulse of the present utility model;
Fig. 2 is reception, the treating apparatus circuit theory of optical time domain reflectometer light pulse of the present utility model;
Fig. 3 is the curve map of 20 meters single-mode fibers;
Fig. 4 is 9081 meters curve maps that are connected with 8192 meters single-mode fibers.
Wherein: R1～R8 resistance N1～N3 operational amplifier C1 electric capacity K1～K4 relay contact
RP1, RP2 potentiometer V1 diode B1 optical receiver IC 1 A/D converter
Embodiment
Be described further below in conjunction with reception, the treating apparatus of accompanying drawing optical time domain reflectometer light pulse of the present utility model:
As shown in Figure 1: the reception of this optical time domain reflectometer light pulse, treating apparatus, the reception, the processor that mainly comprise light pulse transmitter and light pulse, fiber coupler links to each other with A/D converter by optical receiver InGaAs APD, current-to-voltage convertor, variable gain amplifier, fixed gain amplifier, filter controller, filter network, the light pulse transmitter is linked testing fiber by fiber coupler, and light pulse reception, processor then fiber coupler receive and handle the signal that returns from testing fiber.
As shown in Figure 2: assemble reception, the treating apparatus of the optical time domain reflectometer light pulse of a playscript with stage directions utility model, circuit structure and function are as follows:
Optical receiver B1 adopts high-responsivity optical receiver InGaAs APD, and its positive pole connects-45V, and negative pole connects the inverting input of operational amplifier N1.Be connected to diode V1 and resistance R 1 between the inverting input of operational amplifier N1 and the output terminal, the positive input end grounding of operational amplifier N1, the output terminal of operational amplifier N1 also connect the Vi pin of operational amplifier N2.Operational amplifier N1, resistance R 1 and diode V1 constitute current-to-voltage convertor.
The G1 pin of operational amplifier N2 connects the sliding contact of potentiometer RP1, and the G2 pin connects+end of 1.2V voltage and potentiometer RP1, the other end ground connection of potentiometer RP1.The com pin ground connection of operational amplifier N2.Form variable gain amplifier, conditioning signal intensity as required.
The Vo pin of operational amplifier N2 connects the inverting input of operational amplifier N3 by resistance R 3.The positive input end grounding of operational amplifier N3.The inverting input of operational amplifier N3 connects the sliding contact of potentiometer RP2 by resistance R 2.The two ends of potentiometer RP2 connect respectively+5V and-5V voltage.Be connected to resistance R 4 between the inverting input of operational amplifier N3 and the output terminal.
Relay contact K1 connects with resistance R 5, and relay contact K2 connects with resistance R 6, and relay contact K3 connects with resistance R 7, and relay contact K4 connects with resistance R 8, is connected on respectively then between the output terminal and A/D converter input end of operational amplifier N3.The A/D converter input end is by capacitor C 1 ground connection.Form controlled filter network, as required the noise of each link generation of filtering.
Fig. 3 is the curve map of 20 meters single-mode fibers, and wavelength is 1310 nanometers, and pulse width was 40 nanoseconds, and length measurements is 20 meters.
Fig. 4 is 9081 meters curve maps that are connected with 8192 meters single-mode fibers, and the average loss actual value is 0.194, and wavelength is 1310 nanometers, and pulse width was 2560 nanoseconds, and length measurements is 9081 meters and 8192 meters, and the average loss measured value is 0.194.From above-mentioned two examples the utility model range performance and the attenuation characteristic of measuring optical fiber preferably can be described, realize the purpose of this utility model by the multiple technologies means.
The course of work is as follows:
-45V is used to provide the required negative pressure of operate as normal to setover, and when having signal to return from tested optical fiber, high-responsivity optical receiver InGaAs APD can produce a certain size electric current, and the size of this electric current is proportional to the power of light signal.Operational amplifier N1, resistance R 1 and diode V1 constitute current-to-voltage convertor, and the output of this link is voltage signal, and its size is proportional to the current value of input.If input current is bigger, the voltage of output is also bigger, if voltage surpasses the forward voltage of diode V1, diode V1 is conducting, thereby avoided operational amplifier N1 to enter the situation of state of saturation.Another effect of diode V1 is to utilize its junction capacity to weaken the vibration of pulse edge.In general, the output of current-to-voltage convertor is still fainter, need further to amplify, and because different optical fiber, the ratio of scattering and reflection is different, enlargement factor needs to adjust as the case may be, therefore the design has adopted a variable gain amplifier N2, for guaranteeing that gain is big, the requirement that noise is low, can adopt integrated circuit AD600 to serve as variable gain amplifier, its enlargement factor can be realized the voltage difference between variable gain amplifier N2 pin G1 and the pin G2 is controlled by adjusting potentiometer RP1 by the control of the voltage difference between pin G1 and the pin G2.The fixed gain amplifying circuit that operational amplifier N3, resistance R 2, resistance R 3 and resistance R 4 constitute is adjusted to certain amplitude to the analog voltage signal of importing and in the scope that A/D converter can be changed.The effect of potentiometer RP2 is to raise or reduce DC level, and simulating signal is adjusted in the scope that A/D converter can change.Why biasing circuit is located at the reverse input end of operational amplifier N3, rather than positive input, be that this will simplify the kind of calculating and reducing device owing to the enlargement factor of operational amplifier under this connected mode becomes simple proportional relation with the resistance of resistance R 4.Simulating signal has been passed through a plurality of links such as current-to-voltage convertor, variable gain amplifier and fixed gain amplifier, and each link all can be introduced noise, in order to improve the signal to noise ratio (S/N ratio) of signal, so will carry out filtering to signal.Because different test case, the characteristic of noise, the characteristic of useful signal are different, so the design has adopted a filter network.This filter network is made up of resistance R 5～R8 and capacitor C 1, resistance R 5～R8 forms the RC wave filter with capacitor C 1 respectively, because they get different resistances, so each wave filter has different filtering characteristics, this link makes instrument can select the wave filter of different qualities according to actual conditions.The selection of different wave filters realizes that by the filter controller that relay K 1～K4 constitutes relay K 1～K4 can adopt the high frequency relay of TQ2 series.Relay K 1～K4 can distinguish conducting, thereby makes signal pass through different wave filters.Simulating signal enters A/D converter and converts digital signal to through after this a series of processing.
Claims (6)
1, the reception of optical time domain reflectometer light pulse, treating apparatus, comprise optical receiver B1, A/D converter, it is characterized in that: optical receiver B1 links to each other with A/D converter by current-to-voltage convertor, variable gain amplifier, fixed gain amplifier, filter controller, filter network.
2, the reception of optical time domain reflectometer light pulse according to claim 1, treating apparatus, it is characterized in that: current-to-voltage convertor comprises operational amplifier N1, diode V1 and resistance R 1, is connected to diode V1 and resistance R 1 between the inverting input of operational amplifier N1 and the output terminal.
3, the reception of optical time domain reflectometer light pulse according to claim 1, treating apparatus, it is characterized in that: fixed gain amplifier comprises operational amplifier N3, resistance R 2-R4, the inverting input of resistance R 2, a R3 termination operational amplifier N3 in parallel, resistance R 4 is attempted by inverting input and the output terminal of operational amplifier N3.
4, the reception of optical time domain reflectometer light pulse according to claim 1, treating apparatus, it is characterized in that: variable gain amplifier comprises operational amplifier N2, potentiometer RP1, the G1 pin of operational amplifier N2 connects the sliding contact of potentiometer RP1, the G2 pin connects+end of 1.2V voltage and potentiometer RP1, the other end ground connection of potentiometer RP1, the com pin ground connection of operational amplifier N2.
5, the reception of optical time domain reflectometer light pulse according to claim 1, treating apparatus is characterized in that: filter network comprises one or more different wave filters.
6, the reception of optical time domain reflectometer light pulse according to claim 1, treating apparatus is characterized in that: filter controller comprises one or more relay contacts, and the contact links to each other with wave filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CNU2005200813592U CN2788167Y (en) | 2005-01-27 | 2005-01-27 | Optical impulse receiving and processing device for optical time domain reflect meter |
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| CNU2005200813592U CN2788167Y (en) | 2005-01-27 | 2005-01-27 | Optical impulse receiving and processing device for optical time domain reflect meter |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101170360B (en) * | 2006-10-25 | 2011-05-11 | 中兴通讯股份有限公司 | A signal optical power detection device and detection method |
| CN102455246A (en) * | 2011-12-12 | 2012-05-16 | 山东信通电器有限公司 | Low-noise and anti-interference optical-time-domain reflectometer with secondary shielding |
| CN103124193B (en) * | 2011-11-21 | 2015-11-18 | 上海光家仪器仪表有限公司 | Based on the multifunctional light time-domain reflectomer of embedded system |
-
2005
- 2005-01-27 CN CNU2005200813592U patent/CN2788167Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101170360B (en) * | 2006-10-25 | 2011-05-11 | 中兴通讯股份有限公司 | A signal optical power detection device and detection method |
| CN103124193B (en) * | 2011-11-21 | 2015-11-18 | 上海光家仪器仪表有限公司 | Based on the multifunctional light time-domain reflectomer of embedded system |
| CN102455246A (en) * | 2011-12-12 | 2012-05-16 | 山东信通电器有限公司 | Low-noise and anti-interference optical-time-domain reflectometer with secondary shielding |
| CN102455246B (en) * | 2011-12-12 | 2014-07-02 | 山东信通电器有限公司 | Low-noise and anti-interference optical-time-domain reflectometer with secondary shielding |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C56 | Change in the name or address of the patentee |
Owner name: SHANDONG KEHUI POWER AUTOMATION CO., LTD. Free format text: FORMER NAME: ZIBO KEHUI ELECTRIC CO., LTD. |
|
| CP03 | Change of name, title or address |
Address after: 255087 Shandong Province, Zibo city Zhangdian District Fang Zhen win Road No. 16 Patentee after: Shandong Kehui Electric Co., Ltd. Address before: 255087 Shandong Province, Zibo city Zhangdian District in the first northbound road win Patentee before: Kehui Electrics Co., Ltd., Zibo |
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| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20060614 Termination date: 20140127 |