CN103901262A

CN103901262A - Nanosecond level pulse peak value detection method

Info

Publication number: CN103901262A
Application number: CN201410144169.4A
Authority: CN
Inventors: 杨爱英; 张卿; 冯立辉
Original assignee: Beijing Institute of Technology BIT
Current assignee: Beijing Institute of Technology BIT
Priority date: 2014-04-11
Filing date: 2014-04-11
Publication date: 2014-07-02

Abstract

The invention relates to a nanosecond level pulse peak value detection method and belongs to the technical field of optical communication. According to the method, a nanosecond level pulse signal is broadened through a low-pass filter, then, a clock signal obtained after phase position adjustment is triggered, and therefore an analog-digital converter can sample data more accurately. Under the condition that a high-speed analog-digital converter is not needed, a nanosecond level pulse signal peak value can be detected. With the detection method, the requirement for the sampling rate of an analog-to-digital conversion unit can be lowered, the method is simple and easy to perform, and cost of the needed devices is low.

Description

A kind of nanosecond pulse peak-value detection method

Technical field

The present invention relates to a kind of nanosecond pulse peak-value detection method, belong to optical communication technique field.

Background technology

Under the promotion of high-speed broadband data service, in optical-fiber network, the wdm system of 40Gbit/s, 100Gbit/s single channel speed has started commercialization.But, due to the restriction of electronic bottleneck, traditional wideband electronic surveying instrument by electricity sample be difficult to at a high speed even ultra high-speed optical signal of communication directly measure.Therefore, must adopt Optical Sampling method to measure high speed optical communication signal.For digital communication system, the index of weighing its communication quality is the bit error rate.The measurement of the bit error rate can be monitored by the Q factor of measuring digital signal.Research shows, the signal after Optical Sampling is converted to nanosecond electric impulse signal through photodetector, and the peak value measurement of electric pulse can be rebuild the eye pattern of high-speed light data-signal and record its Q factor.Therefore, the detection of nanosecond electric pulse peak value is the gordian technique of measuring ultra high-speed optical data signal quality.

For the electric impulse signal of nanosecond, directly use high speed acquisition circuit to be difficult to capture in real time its peak value, therefore need to design the peak holding circuit of narrow pulse signal, this circuit carries out broadening and keeps a period of time the signal of front-end amplifier output, to adopt conventional low speed rotation parallel operation to carry out acquisition process.But repetition frequency is burst pulse peak holding circuit more than megahertz, its switching rate, peak value detect time delay and peak value keeps being all faced with strict demand, design comparison complexity release time.For this reason, can adopt the hypervelocity AD conversion unit of 1GHz sampling rate and ultra-high-speed data acquisition card that field programmable gate array (FPGA) unit is core to detect pulsewidth is that nanosecond order, repetition frequency are the narrow pulse signal peak value of megahertz level.This scheme does not need peak holding circuit just can obtain the peak value of pulse, but the method cost is higher.

Summary of the invention

The object of the invention is, for solving existing nanosecond pulse peak value detection design complexity, problem that cost is high, to propose a kind of nanosecond pulse peak-value detection method.

A kind of nanosecond pulse peak-value detection method, specifically comprises the following steps:

Step 1: tested random light pulse signal, through photodetector, is converted to the random electric impulse signal of nanosecond.

Step 2: the random electric impulse signal that step 1 is obtained carries out low-pass filtering by wave filter, realizes pulse strenching; Filter bandwidht is greater than pulse repetition rate and is less than pulse bandwidth.

Step 3: using periodic optical pulse as sampling source, be converted to periodically electric impulse signal through photodetector; The repetition frequency of periodic optical pulse is identical with the repetition frequency of the tested random light pulse signal of step 1.

Step 4: the periodicity electric impulse signal that step 3 is obtained carries out phase-locked operation, clocking; The phase place of dynamic adjustments clock signal, makes its rising edge align with the peak with mechanical-electronic pulse.

Step 5: after the broadening that step 2 is obtained, random electric impulse signal is sampled under the clock signal of step 4 triggers, and then carries out analog to digital conversion, obtains the peak value of nanosecond random pulses.

Beneficial effect

The present invention, by using low-pass filter by nanosecond pulse signal broadening, makes more accurately sampled data of analog to digital converter.Under the condition without high-speed AD converter, can detect the peak value of nanosecond pulse signal.This detection method can reduce the requirement to AD conversion unit sampling rate, simple, and required device cost is low.

Accompanying drawing explanation

Fig. 1 is the process flow diagram of a kind of nanosecond pulse peak-value detection method provided by the invention;

Fig. 2 is that random electric impulse signal is by before wave filter and by the pulse width comparison diagram after wave filter;

Fig. 3 is a kind of nanosecond pulse peak detection system figure implementing according to a kind of nanosecond pulse peak-value detection method provided by the invention;

Fig. 4 is the signal sequence schematic diagram in a kind of nanosecond pulse peak detection system of implementing according to a kind of nanosecond pulse peak-value detection method provided by the invention.

Embodiment

Further describe according to drawings and embodiments embodiments of the present invention below.

A kind of nanosecond pulse peak detection system of implementing according to a kind of nanosecond pulse peak-value detection method provided by the invention as shown in Figure 3, comprises periodic optical pulse generator, the first photodetector, the second photodetector, random light pulse signal generation module, clock signal generating module, analog to digital converter and filtering circuit.Wherein, clock signal generating module comprises phase-locked processing submodule and phase adjusted submodule.

The output of periodic optical pulse generator is connected to the first photodetector, the output of the first photodetector is connected with the phase-locked processing submodule of clock signal generating module, phase-locked processing submodule is connected with phase adjusted submodule, and the output of phase adjusted submodule is as clock signal input analog-to-digital converter.The output of random light pulse signal generation module connects the second photodetector, and the output of the second photodetector is connected to filtering circuit, and the output of filtering circuit is connected to analog to digital converter.

Periodic optical pulse generator produces periodic optical pulse signal, carries out opto-electronic conversion by the first photodetector, produces periodically electric impulse signal;

Periodically electric impulse signal enters clock signal generating module and carries out phase-lockedly, produces square wave clock signal, then obtains phase locked square wave clock signal through phase adjusted;

Described phase regulation method is: in clock signal generating module, by the clock signal phase after phase-locked according to etc. step-length traversal one-period (360 °), each phase position in ergodic process is sampled and is obtained frame sampling data, calculate the variance of every frame sampling data and compare, write down phase position corresponding to variance maximal value, phase place is adjusted to this position, then carries out data output.

Random light pulse signal generation module produces random light pulse, is converted to the random electric impulse signal of nanosecond by the second photodetector;

The random electric impulse signal of nanosecond, by filtering circuit, by filtering noise stretched pulse, obtains the random electric impulse signal after broadening;

The square wave clock signal trigger mode number converter of homophase, the random electric impulse signal sampling after making it to broadening, gathers the peak value with mechanical-electronic pulse, and carries out numeral and export.

The periodic optical pulse that periodic optical pulse generator produces has the identical recurrence interval with the random light pulse that random light pulse signal generation module produces; Periodicity electric impulse signal enters digital signal processing module and carries out phase-locked generation square wave clock signal, now the rising edge of square wave clock signal does not align with the peak value of pulse point of random electric impulse signal, cannot guarantee accurately to collect peak value of pulse after trigger mode number converter; After phase adjusted, obtain square wave clock signal, its rising edge aligns with random electric impulse signal peak value of pulse point, after trigger mode number converter, can accurately collect with mechanical-electronic pulse peak value.

The system that a kind of nanosecond pulse peak value provided by the invention detects as shown in Figure 3.Adopt nonlinear polarization passive mode-locking fiber laser to produce the periodic optical pulse signal that repetition frequency is 30MHz, carry out opto-electronic conversion by the first photodetector and produce periodically electric impulse signal.Utilize fpga chip EP3C25E144C8 to complete clock signal generating module function, periodicity electric impulse signal is input in a PLL of FPGA and carries out phase-locked processing, produce square wave clock signal, the another one PLL of recycling FPGA carries out phase adjusted to the square wave clock producing, and its rising edge is alignd with random electric impulse signal peak value of pulse point.In overregulating the square wave clock signal input analog-to-digital converter AD9245 obtaining as analog-to-digital triggering clock signal.

At random light pulse signal generation module, the periodic optical pulse signal that the repetition frequency that random light signal and nonlinear polarization passive mode-locking fiber laser produce is 30MHz produces in periodically poled lithium niobate (PPLN) waveguide and frequency effect obtains random light pulse signal, is converted to the random electric impulse signal of nanosecond by the second photodetector.Random electric impulse signal, through adopting after the second-order low-pass filter circuit that the bandwidth of operational amplifier chip OPA695 design is 50MHz, by noise filtering stretched pulse, obtains the random electric impulse signal after broadening.Figure 2 shows that the pulse width comparison diagram of experiment gained filtering front and back.In random electric impulse signal input analog-to-digital converter AD9245 after broadening, under the triggering of clock signal, carry out analog to digital conversion, gather random electric impulse signal peak value and carry out numeral output.

Fig. 4 is the sequential schematic diagram of signal in a kind of detection system for implementing according to a kind of nanosecond pulse peak-value detection method provided by the invention.Wherein, signal 1 is random pulse sequence, and signal 2 is the random pulse sequence after broadening, and signal 3 is periodic pulse train, signal 4 for periodic pulse train enter digital signal processing module produce square wave clock signal.Now the rising edge of square wave clock signal not necessarily aligns with the peak value of pulse point of randomly pulsed phase signal.Signal 5 is the square wave clock signal after phase place regulates automatically, and its rising edge aligns with the peak point of random pulses.

Above the present invention's " a kind of nanosecond pulse peak-value detection method " is had been described in detail, but specific embodiment of the invention form is not limited to this.The explanation of this enforcement is just for helping to understand method of the present invention and core concept thereof; , for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention meanwhile.In the case of not deviating from the various apparent change of the spirit of the method for the invention and claim scope, it being carried out all within protection scope of the present invention.

Claims

1. a nanosecond pulse peak-value detection method, is characterized in that: comprise the following steps:

Step 1: tested random light pulse signal, through photodetector, is converted to the random electric impulse signal of nanosecond;

Step 2: the random electric impulse signal that step 1 is obtained carries out low-pass filtering by wave filter, realizes pulse strenching; Filter bandwidht is greater than pulse repetition rate and is less than pulse bandwidth;

Step 3: using periodic optical pulse as sampling source, be converted to periodically electric impulse signal through photodetector; The repetition frequency of periodic optical pulse is identical with the repetition frequency of the tested random light pulse signal of step 1;

Step 4: the periodicity electric impulse signal that step 3 is obtained carries out phase-locked operation, clocking; The phase place of dynamic adjustments clock signal, makes its rising edge align with the peak with mechanical-electronic pulse;

2. a kind of nanosecond pulse peak-value detection method according to claim 1, it is characterized in that: the method for the phase place of dynamic adjustments clock signal is: by clock signal phase according to etc. 360 ° of step-length traversal one-periods, each phase position in ergodic process is sampled and is obtained frame sampling data, calculate the variance of every frame sampling data and compare, write down phase position corresponding to variance maximal value, clock signal phase is adjusted to this position.