CN103823175A - Photoelectric detection circuit frequency response characteristic test method based on OTDR - Google Patents
Photoelectric detection circuit frequency response characteristic test method based on OTDR Download PDFInfo
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Abstract
The invention relates to a photoelectric detection circuit frequency response characteristic test method based on an OTDR. The test method comprises a test device which includes a pulse light source generator, an optical circulator, an auxiliary fiber, a detection circuit to be detected, a data acquisition module and a computer. A specific pulse width and the pulse light of a frequency, which are emitted by the pulse light source generator, enter the optical circulator and enter the auxiliary fiber through the optical circulator, the reflection light of a fiber enters the detection circuit to be detected through the optical circulator, the photoelectric signal outputted by the detection circuit to be detected is accessed to the data acquisition module, the data acquisition module is in charge of communicating with the computer so as to transmit acquired signals to the computer for spectrum analysis, and by comparing a frequency spectrum with a known frequency spectrum of a pulse light source, the real frequency response characteristic of the detection circuit is obtained. The test method provided by the invention truly reflects the frequency spectrum characteristic of the detection circuit to be detected, the structural composition is simple, the operation is easy, and the test method is rapid and convenient.
Description
Technical field
The invention belongs to photodetection field, be specially a kind of method of testing of the photodetection circuit Frequency Response based on OTDR, be applicable to the frequency response parameter testing of various photodetection circuit.
Background technology
In photodetection field, the frequency response of detection circuit directly affects the real response of system to different spectral light signal, and then affects the actual response ability of system to measured target.As in the distributed temperature measuring system based on optical fiber, the temperature measurement accuracy of system will directly be affected if the frequency response of detection circuit is too low.Therefore in the various systems based on photodetection, the Frequency Response test of detection circuit will be very important link.
Common method of testing is to depart from photo-detector, the simple frequency response that utilizes various electricity instruments to measure detection circuit from the transport property of circuit.Because the actual pumping signal adding not is the signal that detector truly provides, therefore test result certainty and physical presence different.
Rise recently a kind of method of testing of the detection of the first harmonic based on lock-in amplifier principle, its ultimate principle is that the sinusoidal signal that signal generator produces characteristic frequency is modulated light source that can external modulation, light after modulation changes by photodetector and Circuit responce output electrical signals thereof, this signal is detected as first harmonic signal by lock-in amplifier, the sinusoidal signal frequency that changes like this, within the specific limits signal generator generation just can obtain the frequency response of detection circuit to be measured.The method adopts actual detector to export as pumping signal, can react really within the specific limits the characteristic of detection circuit, but system is more complicated, be not suitable for other system integrated, be difficult to realize test robotization.
Summary of the invention
The object of the invention is to overcome above-mentioned the deficiencies in the prior art, a kind of method of testing of the photodetection circuit Frequency Response based on OTDR is provided.Method of testing of the present invention wants to reflect truly the spectral characteristic of detection circuit to be measured, and total forms simple easy operating, and test mode is all efficient and convenient.
In order to reach foregoing invention object, the technical scheme that patent of the present invention provides is as follows:
A kind of photodetection circuit Frequency Response method of testing based on OTDR, it is characterized in that, in this method of testing, be provided with proving installation, this proving installation includes light-pulse generator generator, optical circulator, auxiliary optical fiber, detection circuit to be measured, data acquisition module and computing machine, described optical circulator input end connects light-pulse generator generator with received pulse light, an output terminal of optical circulator connects auxiliary optical fiber to receive utilizing emitted light, another output terminal connection data acquisition module of optical circulator, this data acquisition module connects computing machine, this method of testing includes following steps:
The first step, debugging light-pulse generator generator, makes its pulsed light that sends fixed pulse width and fixed frequency, and this pulsed light is access in to described optical circulator;
Second step, an output terminal of described optical circulator connects auxiliary optical fiber, the length of this auxiliary optical fiber and the pulsewidth of pulsed light have following relation: L > 10*2*t*v, wherein L is the length of auxiliary optical fiber, unit is rice, and t is pulsewidth, and unit is nanosecond, v is the velocity of propagation of laser in optical fiber, and unit is metre per second (m/s);
The 3rd step, the reflected light in auxiliary optical fiber enters optical circulator, and by optical circulator output optical signal, to data acquisition module, this data acquisition module carries out analog to digital conversion to the light signal collecting, and the digital signal after changing is sent in computing machine;
The 4th step, carries out spectrum analysis by computing machine to the digital signal receiving, and contrasts with the light source pulse frequency spectrum of light-pulse generator generator, thereby determines the Frequency Response of detection circuit to be measured.
In the photodetection circuit Frequency Response method of testing that the present invention is based on OTDR, described light-pulse generator generator or be laser pulse light source module, or can modulated light source for what adopt signal generator modulation.
In the photodetection circuit Frequency Response method of testing that the present invention is based on OTDR, described data acquisition module is that frequency is the high-Speed Data-Acquisition Module of 100MHz, and this data acquisition module adopts RJ45 interface with communicating by letter of computing machine.
In the photodetection circuit Frequency Response method of testing that the present invention is based on OTDR, described computing machine carries out spectrum analysis to digital signal: adopt mathematical software matlab to carry out fast Fourier FFT conversion to the data that collect, the spectrum curve of drawing data, in order to reduce the impact of system noise on signal as far as possible, get ten spectrum curves and average, obtain the final spectrum curve of digital signal; Same also does identical spectrum analysis to light source pulse, draws the spectrum curve of light source pulse, and draw a light source pulse frequency spectrum-3dB curve; By final the digital signal obtaining spectrum curve and light source pulse frequency spectrum-3dB curve compares, the frequency spectrum point of two curve intersections is the bandwidth of circuit under test, also can find out the flatness of circuit under test in same frequency band simultaneously from signal spectrum curve.
Based on technique scheme, the photodetection circuit Frequency Response method of testing that the present invention is based on OTDR has in use obtained following technique effect: the optical principle that patent utilization of the present invention is basic, adopt the photosignal of detector output as the driving source of test, can measure really the response of detection circuit in each frequency range.Owing to adopting pulsed light as pumping signal, when use, can reduce significantly testing time.In addition, in the time that the gain of detection circuit is very high, the reflected signal that system adopts circulator to measure auxiliary optical fiber will become very necessary, thereby make whole system be convenient to the integrated commercialization that is easy to.
Accompanying drawing explanation
Fig. 1 is the connection diagram that the present invention is based on the proving installation of the photodetection circuit Frequency Response method of testing of OTDR.
Fig. 2 is the schematic flow sheet that the present invention is based on the photodetection circuit Frequency Response method of testing of OTDR.
Embodiment
We are described in detail detection circuit Frequency Response method of testing of the present invention with specific embodiment by reference to the accompanying drawings below; in the hope of more cheer and bright understanding architectural feature of the present invention and workflow, but can not limit the scope of the invention with this.
As shown in Figure 1, the present invention is based on and in the proving installation in the photodetection circuit Frequency Response method of testing of OTDR, mainly include following several parts composition: this proving installation includes light-pulse generator generator 1, optical circulator 2, auxiliary optical fiber 3, detection circuit to be measured 4, data acquisition module 5 and computing machine 6.Wherein, optical circulator 2 input ends connect light-pulse generator generator 1 with received pulse light, an output terminal of optical circulator 2 connects auxiliary optical fiber 3 to receive utilizing emitted light, another output terminal connection data acquisition module 5 of optical circulator 2, with by optical signal transmission to data acquisition module 4, this data acquisition module 5 connects computing machine 6.
Critical piece wherein includes: 1. light-pulse generator.The light-pulse generator adopting in embodiment is the laser pulse light source module of Shanghai Bohui Communication Technology Co., Ltd..This module by can electrical modulation continuous light source part and modulating pulse output two parts form.Modulating pulse output output electric pulse signal, this signal is modulated final output optical pulse to continuous light source.Pulsed light wavelength 1550nm, pulsewidth is 100ns, frequency is 10KHz.What the light-pulse generator generator here also can adopt signal generator modulation can modulated light source.
2. optical circulator.Optical circulator is responsible for collecting the reflected signal of auxiliary optical fiber.One port of circulator is light inlet, and two ports connect auxiliary optical fiber, exports from three ports from the light of auxiliary fiber reflection, and three ports connect photodetector, and the light of reflection is carried out to acquisition process.
3. auxiliary optical fiber.Auxiliary optical fiber in embodiment adopts the telecommunication optical fiber of standard, and length is 500 meters.Short fiber length can be calculated with following formula in theory:
L=2*t*v
Wherein: L is short fiber length;
T is light impulse length;
V is the velocity of propagation of laser in optical fiber.
In order to obtain better experiment effect, suggestion is longer by optical fiber choosing, is not generally less than 10 times of theoretical values.
4. data acquisition module.Data acquisition module adopts the high-Speed Data-Acquisition Module of Shanghai Bohui Communication Technology Co., Ltd., and sample frequency is 100MHz, adopts RJ45 interface with communicating by letter of computing machine.This data acquisition module is mainly made up of photodetection circuit and data acquisition circuit two parts, and wherein photodetection circuit is responsible for the light signal of retroreflection to be converted to electric signal and to carry out suitable amplification, and enlargement factor should be in megohm magnitude; High Speed Data Acquisition Circuit is sampled the electric signal after amplifying, and the signal collecting is uploaded to computing machine analysis by RJ45 interface.
5. computing machine.Adopt common PC.In this computer, pre-install matlab data processor, this program is responsible for and the communicating by letter and the analysis of digital signal of data acquisition module.Obtain the frequency spectrum of signal by fft analysis, then the frequency spectrum of ten times is averaging, export final signal spectrum.By the final spectrum curve obtaining and light source pulse frequency spectrum-3dB spectrum curve compares, and can draw the bandwidth of circuit under test.
As shown in Figure 2, the present invention is based on the groundwork flow process of photodetection circuit Frequency Response method of testing of OTDR as follows:
The first step, debugging light-pulse generator generator, makes its pulsed light that sends fixed pulse width and fixed frequency, and this pulsed light is access in to described optical circulator;
Second step, an output terminal of described optical circulator connects auxiliary optical fiber, the length of this auxiliary optical fiber and the pulsewidth of pulsed light have following relation: L > 10*2*t*v, wherein L is the length of auxiliary optical fiber, unit is rice, and t is pulsewidth, and unit is nanosecond, v is the velocity of propagation of laser in optical fiber, and unit is metre per second (m/s);
The 3rd step, the reflected light in auxiliary optical fiber enters optical circulator, and by optical circulator output optical signal, to data acquisition module, this data acquisition module carries out analog to digital conversion to the light signal collecting, and the digital signal after changing is sent in computing machine;
The 4th step, carries out spectrum analysis by computing machine to the digital signal receiving, and contrasts with the light source pulse frequency spectrum of light-pulse generator generator, thereby determines the Frequency Response of detection circuit to be measured.
In the photodetection circuit Frequency Response method of testing that the present invention is based on OTDR, described computing machine carries out spectrum analysis to digital signal: adopt matlab software to carry out Fast Fourier Transform (FFT) (fast Fourier transform to the data that collect, be called for short FFT conversion), the spectrum curve of drawing data, in order to reduce the impact of system noise on signal as far as possible, get ten spectrum curves and average, obtain the final spectrum curve of digital signal; Same also does identical spectrum analysis to light source pulse, draws the spectrum curve of light source pulse, and draw a light source pulse frequency spectrum-3dB curve; By final the digital signal obtaining spectrum curve and light source pulse frequency spectrum-3dB curve compares, the frequency spectrum point of two curve intersections is the bandwidth of circuit under test, also can find out the flatness of circuit under test in same frequency band simultaneously from signal spectrum curve.
The laser that in method of testing of the present invention, light-pulse generator is sent enters in auxiliary optical fiber through circulator, while transmission, can produce reflected light in optical fiber, this reflected light is entered in detection circuit to be measured by circulator, detection circuit is converted to electric signal for data collecting module collected by light signal, the signal collecting uploads in host computer, by simple algorithm, it is carried out to spectrum analysis.The frequency spectrum of the light signal that light-pulse generator is sent is known, by obtaining the real Frequency Response of detection circuit to the contrast of detection circuit output signal spectrum and light-pulse generator signal spectrum.
Claims (4)
1. the photodetection circuit Frequency Response method of testing based on OTDR, it is characterized in that, in this method of testing, be provided with proving installation, this proving installation includes light-pulse generator generator, optical circulator, auxiliary optical fiber, detection circuit to be measured, data acquisition module and computing machine, described optical circulator input end connects light-pulse generator generator with received pulse light, an output terminal of optical circulator connects auxiliary optical fiber to receive utilizing emitted light, another output terminal connection data acquisition module of optical circulator, this data acquisition module connects computing machine, this method of testing includes following steps:
The first step, debugging light-pulse generator generator, makes its pulsed light that sends fixed pulse width and fixed frequency, and this pulsed light is access in to described optical circulator;
Second step, an output terminal of described optical circulator connects auxiliary optical fiber, the length of this auxiliary optical fiber and the pulsewidth of pulsed light have following relation: L > 10*2*t*v, wherein L is the length of auxiliary optical fiber, unit is rice, and t is pulsewidth, and unit is nanosecond, v is the velocity of propagation of laser in optical fiber, and unit is metre per second (m/s);
The 3rd step, the reflected light in auxiliary optical fiber enters optical circulator, and by optical circulator output optical signal, to data acquisition module, this data acquisition module carries out analog to digital conversion to the light signal collecting, and the digital signal after changing is sent in computing machine;
The 4th step, carries out spectrum analysis by computing machine to the digital signal receiving, and contrasts with the light source pulse frequency spectrum of light-pulse generator generator, thereby determines the Frequency Response of detection circuit to be measured.
2. a kind of photodetection circuit Frequency Response method of testing based on OTDR according to claim 1, is characterized in that, described light-pulse generator generator or be laser pulse light source module, or can modulated light source for what adopt signal generator modulation.
3. a kind of photodetection circuit Frequency Response method of testing based on OTDR according to claim 1, it is characterized in that, described data acquisition module is that frequency is the high-Speed Data-Acquisition Module of 100MHz, and this data acquisition module adopts RJ45 interface with communicating by letter of computing machine.
4. a kind of photodetection circuit Frequency Response method of testing based on OTDR according to claim 1, it is characterized in that, described computing machine carries out spectrum analysis to digital signal: adopt matlab software to carry out fast Flourier FFT conversion to the data that collect, the spectrum curve of drawing data, in order to reduce the impact of system noise on signal as far as possible, get ten spectrum curves and average, obtain the final spectrum curve of digital signal; Same also does identical spectrum analysis to light source pulse, draws the spectrum curve of light source pulse, and draw a light source pulse frequency spectrum-3dB curve; By final the digital signal obtaining spectrum curve and light source pulse frequency spectrum-3dB curve compares, the frequency spectrum point of two curve intersections is the bandwidth of circuit under test, also can find out the flatness of circuit under test in passband simultaneously from signal spectrum curve.
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| CN112099037A (en) * | 2020-09-17 | 2020-12-18 | 上海波汇科技有限公司 | Target detection method and device based on FMCW laser radar high point cloud acquisition quantity |
| CN112858805A (en) * | 2020-12-29 | 2021-05-28 | 西南技术物理研究所 | Frequency response characteristic parameter measuring device for quadrant photoelectric detector |
| CN113091795A (en) * | 2021-03-29 | 2021-07-09 | 上海橙科微电子科技有限公司 | Method, system, device and medium for measuring photoelectric device and channel |
| CN114112006A (en) * | 2021-11-26 | 2022-03-01 | 中科传启（苏州）科技有限公司 | Noise monitoring method and device and electronic equipment |
| CN115347952A (en) * | 2022-10-19 | 2022-11-15 | 高勘(广州)技术有限公司 | Optical path testing method, device, equipment and storage medium |
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| CN114112006A (en) * | 2021-11-26 | 2022-03-01 | 中科传启（苏州）科技有限公司 | Noise monitoring method and device and electronic equipment |
| CN115347952A (en) * | 2022-10-19 | 2022-11-15 | 高勘(广州)技术有限公司 | Optical path testing method, device, equipment and storage medium |
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