CN114726437B - Digital optical transmitter edge jitter detector - Google Patents

Abstract

An edge jitter detector and a detection method of a digital optical transmitter belong to the technical field of digital signal parameter measurement. The digital optical transmitter edge jitter detector includes a 1×2 optical splitter, a third photodetector, a clock data recovery module, a clock splitter, a clock frequency multiplication and shaping module, an optical fiber delay line, a dual-port modulator, A first photodetector, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter, an edge jitter measurement module, and a system control and data processing module. An edge jitter detector and a detection method of a digital optical transmitter provided by the invention measure all edge signals one by one in a measurement time period, which greatly improves the measurement effectiveness and reduces the parameter requirements for components in the measurement process. and resource overhead, solving the technical bottleneck in traditional measurement methods.

Description

A Digital Optical Transmitter Edge Jitter Detector

technical field

The invention belongs to the technical field of digital signal parameter measurement, and in particular relates to an edge jitter detector and a detection method of a digital optical transmitter.

Background technique

Digital signal parameter measurement is an important detection process in digital communication. It mainly obtains key technical parameters such as signal rate, amplitude, edge jitter, etc., which is of great significance to ensure the normal establishment of digital communication links and low bit error rate transmission. Among them, edge jitter measurement is a key measurement process, which can be used to evaluate the quality of the output signal of the transmitter.

The edge jitter size and probability distribution of the output optical signal of the digital optical transmitter are directly related to the receiver's judgment on the input signal. Too high jitter will lead to reception errors. The existing measurement method mainly collects the signal eye diagram of the optical transmitter through a high-speed oscilloscope, and estimates the size of the edge jitter based on the height and width of the eye diagram. In this measurement method, the sampling rate of the oscilloscope is much higher than the transmission code rate of the digital signal, generally greater than 10 times, and the signal waveform data needs to be recorded in real time during the measurement process, which requires the oscilloscope to have a large storage depth. These requirements greatly restrict the real-time jitter measurement of high-bit-rate optical signals, and its system complexity and cost limit the wide application of this method in engineering testing.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an edge jitter detector and a detection method for a digital optical transmitter in view of the defects in the background art.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A digital optical transmitter edge jitter detector, comprising:

The 1×2 optical splitter is used to divide the intensity-modulated optical signal string output by the digital optical transmitter into two channels, which are respectively input to the fiber delay line and the third photodetector;

The third photodetector is used to restore the received optical signal string to an electrical signal string, and input the clock data recovery module;

The clock data recovery module is used to recover the digital signal output by the digital optical transmitter and the reference clock of the digital signal from the electrical signal string output by the third photodetector, the reference clock is input to the clock splitter, the digital signal is input to the system control and data processing module;

Clock splitter, used to divide the reference clock into two channels, one input to the system control and data processing module, the other input to the clock multiplication and shaping module;

The clock frequency multiplication and shaping module doubles and reshapes the input reference clock to obtain a signal slice clock, which is output to the dual-port modulator;

The optical fiber delay line, under the control of the optical fiber delay line control signal output by the system control and data processing module, performs controllable delay on the received optical signal string and outputs it to the dual-port modulator;

The dual-port modulator, under the control of the signal slicing clock, slices the optical signal string output by the optical fiber delay line to obtain two optical pulse signals, which are respectively input to the first photodetector and the second photodetector;

The first photodetector and the second photodetector are used to convert the two-path optical pulse signals output by the dual-port modulator into electrical pulse signals, and input them to the first analog-to-digital converter and the second analog-to-digital converter respectively;

The first analog-to-digital converter and the second analog-to-digital converter are used to digitally quantize the electrical pulse signals output by the first photodetector and the second photodetector, and the quantized signal is input to the edge jitter measurement module;

The edge jitter measurement module converts the quantized signals output by the first analog-to-digital converter and the second analog-to-digital converter into edge jitter measurement results, and outputs the result to the system control and data processing module;

The system control and data processing module receives the digital signal of the clock data recovery module, the reference clock output by the clock splitter and the edge jitter measurement result of the edge jitter measurement module, generates the optical fiber delay line control signal and outputs the final edge jitter measurement result.

A detection method based on the above-mentioned digital optical transmitter edge jitter detector, comprising the following steps:

Step S0, setting the initial value of the delay amount of the optical fiber delay line to 0;

Step S1, under the control of the signal slicing clock, the dual-port modulator slices the optical signal string output by the optical fiber delay line to obtain two optical pulse signals, and then passes through the dual-port modulator A port and the dual-port modulator B port respectively. Input to the first photodetector and the second photodetector for photoelectric conversion to obtain two-way electrical pulse signals;

In step S2, the two circuits of electrical pulse signals are digitally quantized in the first analog-to-digital converter and the second analog-to-digital converter, respectively, to obtain two-path quantized signals;

Step S3, define that the edge time of the optical signal string is ahead of the edge time of the signal slice clock as positive jitter, and the edge time of the optical signal string lags behind the edge time of the signal slice clock as negative jitter, and the edge time of the optical signal string is equal to the signal slice clock. zero jitter at the edge moment of ;

The edge jitter measurement module judges the adjacent two sampling values of the first analog-to-digital converter and the second analog-to-digital converter, and obtains the edge jitter measurement result. The specific judgment rules are:

When the sampling value N _A = M of the first analog-to-digital converter, and the sampling value N _B of the second analog-to-digital converter satisfies 0<N _B <M, the edge jitter measurement result is: positive jitter on the rising edge, edge jitter value D ₁ =N _B /M, where M is the full-scale maximum value of the first analog-to-digital converter and the second analog-to-digital converter;

When the sampling value of the first analog-to-digital converter N _A >0.95M, and the sampling value of the second analog-to-digital converter N _B >0, the edge jitter measurement result is: zero jitter on the rising edge, edge jitter value D ₂ =0 ;

When the sampling value of the first analog-to-digital converter N _A <M and the sampling value of the second analog-to-digital converter N _B =0, the edge jitter measurement result is: negative jitter on the rising edge, edge jitter value D ₃ =(MN _A )/M;

When the sampling value of the first analog-to-digital converter N _A =0, and the sampling value of the second analog-to-digital converter N _B <M, the edge jitter measurement result is: positive jitter on the falling edge, edge jitter value D ₄ =(MN _B )/M;

When the sampling value of the first analog-to-digital converter N _A >0, and the sampling value of the second analog-to-digital converter N _B >0.95M, the edge jitter measurement result is: zero jitter on the falling edge, edge jitter value D ₅ =0 ;

When the sampling value of the first analog-to-digital converter N _A =M, and the sampling value of the second analog-to-digital converter N _B <M, the edge jitter measurement result is: negative jitter on the falling edge, edge jitter value D ₆ =N _A /M;

When the system control and data processing module detects the edge transition through the digital signal and the reference clock, the edge jitter measurement result output by the edge jitter measurement module is extracted and stored;

Step S4, the system control and data processing module judges whether the optical signal string and the signal slice clock are aligned according to the edge jitter measurement result stored in step S3; When the optical signal string is aligned with the signal slice clock, steps S1~S3 are executed to start the formal measurement, and the final edge jitter measurement result is output; when all the edge jitter values in the edge jitter measurement result of the optical signal string do not satisfy When the mean value is 0, the optical signal string and the signal slice clock are not aligned. At this time, the system control and data processing module generates the fiber delay line control signal to control the delay amount of the fiber delay line. When the mean value is negative, the fiber delay line is added. When the average value is positive, reduce the delay amount of the optical fiber delay line, and repeat steps S1 to S3 until all edge jitter values in the edge jitter measurement results of the optical signal string satisfy a normal distribution with a mean value of 0.

Further, in step S1, when the signal slice clock is 1, the optical signal string is input to the first photodetector through port A of the dual-port modulator; when the signal slice clock is 0, the optical signal string is passed through the port B of the dual-port modulator. Enter the second photodetector.

Further, in step S2, the sampling time interval T of the first analog-to-digital converter and the second analog-to-digital converter, the sampling rate is the rate of the reference clock output by the clock data recovery module, T=1/ f _CLK3 , f _CLK3 is the frequency of the signal slice clock.

Further, in step S3, the two adjacent sampling values are the sampling value NB of the second analog-to-digital converter at the moment before the edge and the sampling value NA of the first analog _- to _- digital converter at the moment after the edge.

Compared with the prior art, the beneficial effects of the present invention are:

An edge jitter detector and a detection method of a digital optical transmitter provided by the present invention measure all edge signals one by one in a measurement time period, which greatly improves the measurement effectiveness and reduces the parameter requirements for components in the measurement process. and resource overhead, solving the technical bottleneck in traditional measurement methods.

Description of drawings

1 is a schematic structural diagram of a digital optical transmitter edge jitter detector provided by the present invention;

2 is a schematic diagram of an optical signal slicing process of the present invention;

FIG. 3 is a schematic diagram of the judgment process of the edge jitter measurement result.

Detailed ways

A digital optical transmitter edge jitter detector, as shown in Figure 1, includes:

The 1×2 optical splitter is used to divide the intensity-modulated optical signal string output by the digital optical transmitter into two channels, which are respectively input to the fiber delay line and the third photodetector;

The third photodetector is used to restore the received optical signal string to an electrical signal string, and input the clock data recovery module;

The clock data recovery module is used for recovering the digital signal DATA output by the digital optical transmitter and the reference clock CLK ₀ of the digital signal from the electrical signal string output by the third photodetector, and the reference clock CLK ₀ is input to the clock divider, Digital signal DATA input system control and data processing module;

Clock splitter, used to divide the reference clock CLK ₀ into two channels, one channel CLK ₁ is input to the system control and data processing module, and the other channel CLK ₂ is input to the clock multiplication and shaping module;

The clock frequency multiplication and shaping module doubles and reshapes the input reference clock CLK ₂ to obtain the signal slice clock CLK ₃ , which is output to the dual-port modulator;

The optical fiber delay line, under the control of the optical fiber delay line control signal output by the system control and data processing module, performs controllable delay on the received optical signal string and outputs it to the dual-port modulator;

The dual-port modulator, under the control of the signal slicing clock CLK ₃ , slices the optical signal string output by the optical fiber delay line to obtain two optical pulse signals, which are respectively input to the first photodetector and the second photodetector;

The first photodetector and the second photodetector are used to convert the two-path optical pulse signals output by the dual-port modulator into electrical pulse signals, and input them to the first analog-to-digital converter and the second analog-to-digital converter respectively;

The first analog-to-digital converter and the second analog-to-digital converter are used to digitally quantize the electrical pulse signals output by the first photodetector and the second photodetector, and the quantized signal is input to the edge jitter measurement module;

The edge jitter measurement module converts the quantized signals output by the first analog-to-digital converter and the second analog-to-digital converter into edge jitter measurement results, and outputs the result to the system control and data processing module;

The system control and data processing module receives the digital signal DATA of the clock data recovery module, the reference clock CLK ₁ output by the clock splitter and the edge jitter measurement result of the edge jitter measurement module, generates the optical fiber delay line control signal and outputs the final edge jitter measurement results.

A detection method based on the above-mentioned digital optical transmitter edge jitter detector, comprising the following steps:

Step S0, setting the initial value of the delay amount of the optical fiber delay line to 0;

Step S1, under the control of the signal slicing clock CLK ₃ , the dual-port modulator slices the optical signal string output by the optical fiber delay line to obtain two optical pulse signals, and then pass through the dual-port modulator A port (channel A) and The B port (channel B) of the dual-port modulator is input to the first photodetector and the second photodetector for photoelectric conversion to obtain two electrical pulse signals; wherein, when the signal slice clock CLK ₃ is 1, the optical signal serial Port A (channel A) of the dual-port modulator is input to the first photodetector. When the signal slice clock CLK ₃ is 0, the optical signal string is input to the second photodetector through port B (channel B) of the dual-port modulator, as shown in the figure 2 shown;

In step S2, the two circuits of electrical pulse signals are digitally quantized in the first analog-to-digital converter and the second analog-to-digital converter, respectively, to obtain two quantized signals; wherein, the first analog-to-digital converter and the second analog-to-digital converter The sampling time interval T of the converter, the sampling rate is the rate of the reference clock CLK ₀ , T=1/ f _CLK3 , f _CLK3 is the frequency of the signal slice clock; from the basic principle of the analog-to-digital converter, it can be known that it is in the process of voltage signal conversion. , divided into two processes: signal sampling and signal quantization; the analog-to-digital converter samples at the rate of the reference clock CLK ₀ , and its conversion period is 2T, 2T=2/ f _CLK3 =1/ f _CLK0 , f _CLK0 is the reference The frequency of the clock CLK ₀ ; the signal sampling is completed within the T time length, and the signal quantization is completed within the next T time length. In the signal sampling, the signal amplitude obtained by the analog-to-digital converter is the integral of the input voltage signal, and the signal quantization Amplitude is converted to digital signal;

In step S3, after the optical signal string is sliced, there are three types of jitter for the rising edge and the falling edge of the signal. It is defined that the edge time of the optical signal string is ahead of the edge time of the signal slice clock as positive jitter, and the edge time of the optical signal string lags behind the edge time of the signal slice clock as negative jitter, and the edge time of the optical signal string is equal to the edge time of the signal slice clock. zero jitter;

The edge jitter measurement module judges the adjacent two sampling values of the first analog-to-digital converter and the second analog-to-digital converter, and obtains the edge jitter measurement result, as shown in Figure 3; wherein, the two adjacent sampling values be the sampling value N _B of the second analog-to-digital converter at the moment before the edge and the sampling value N _A of the first analog-to-digital converter at the moment after the edge; the specific judgment rule is:

Assuming that the maximum full-scale value of the first analog-to-digital converter and the second analog-to-digital converter is M, the sampling value of the first analog-to-digital converter is N _A , and the sampling value of the second analog-to-digital converter is N _B ;

When the sampling value N _A = M of the first analog-to-digital converter, and the sampling value N _B of the second analog-to-digital converter satisfies 0<N _B <M, the edge jitter measurement result is: positive jitter on the rising edge, edge jitter value D ₁ =N _B /M;

When the sampling value of the first analog-to-digital converter N _A >0.95M, and the sampling value of the second analog-to-digital converter N _B >0, the edge jitter measurement result is: zero jitter on the rising edge, edge jitter value D ₂ =0 ;

When the sampling value of the first analog-to-digital converter N _A <M and the sampling value of the second analog-to-digital converter N _B =0, the edge jitter measurement result is: negative jitter on the rising edge, edge jitter value D ₃ =(MN _A )/M;

When the sampling value of the first analog-to-digital converter N _A =0, and the sampling value of the second analog-to-digital converter N _B <M, the edge jitter measurement result is: positive jitter on the falling edge, edge jitter value D ₄ =(MN _B )/M;

When the sampling value of the first analog-to-digital converter N _A >0, and the sampling value of the second analog-to-digital converter N _B >0.95M, the edge jitter measurement result is: zero jitter on the falling edge, edge jitter value D ₅ =0 ;

When the sampling value of the first analog-to-digital converter N _A =M, and the sampling value of the second analog-to-digital converter N _B <M, the edge jitter measurement result is: negative jitter on the falling edge, edge jitter value D ₆ =N _A /M;

When the system control and data processing module detects the edge jump through the digital signal DATA and the reference clock CLK ₁ , extract and store the edge jitter measurement result output by the edge jitter measurement module;

Step S4, the system control and data processing module judges whether the optical signal string is aligned with the signal slice clock CLK ₃ according to the edge jitter measurement result stored in step S3; when all edge jitter values in the edge jitter measurement result of the optical signal string meet the mean value of 0 When the normal distribution of , the optical signal string is aligned with the signal slice clock, then perform steps S1~S3, start the formal measurement, and output the final edge jitter measurement result; when all the edge jitter values in the edge jitter measurement result of the optical signal string When the normal distribution with mean value of 0 is not satisfied, the optical signal string and the signal slice clock are not aligned. At this time, the system control and data processing module generates the optical fiber delay line control signal to control the delay amount of the optical fiber delay line, and the edge jitter of the optical signal string When the mean value of all edge jitter values in the measurement result is negative, increase the delay amount of the optical fiber delay line, and when the mean value of all edge jitter values in the edge jitter measurement result of the optical signal string is positive, reduce the delay amount of the optical fiber delay line, and repeat step S1 ~S3, until all edge jitter values in the edge jitter measurement result of the optical signal string satisfy a normal distribution with a mean value of 0.

Claims (2)

1. a digital optical transmitter edge jitter detector, is characterized in that, comprises: The 1×2 optical splitter is used to divide the intensity-modulated optical signal string output by the digital optical transmitter into two channels, which are respectively input to the fiber delay line and the third photodetector; The third photodetector is used to restore the received optical signal string to an electrical signal string, and input the clock data recovery module; The clock data recovery module is used to recover the digital signal output by the digital optical transmitter and the reference clock of the digital signal from the electrical signal string output by the third photodetector, the reference clock is input to the clock splitter, the digital signal is input to the system control and data processing module; Clock splitter, used to divide the reference clock into two channels, one input to the system control and data processing module, the other input to the clock multiplication and shaping module; The clock frequency multiplication and shaping module doubles and reshapes the input reference clock to obtain a signal slice clock, which is output to the dual-port modulator; The optical fiber delay line, under the control of the optical fiber delay line control signal output by the system control and data processing module, performs controllable delay on the received optical signal string and outputs it to the dual-port modulator; The dual-port modulator, under the control of the signal slicing clock, slices the optical signal string output by the fiber delay line to obtain two optical pulse signals, which are respectively input to the first photodetector and the second photodetector; when the signal is sliced When the clock is 1, the optical signal string is input to the first photodetector through port A of the dual-port modulator, and when the signal slice clock is 0, the optical signal string is input to the second photodetector through port B of the dual-port modulator; The first photodetector and the second photodetector are used to convert the two-path optical pulse signals output by the dual-port modulator into electrical pulse signals, and input them to the first analog-to-digital converter and the second analog-to-digital converter respectively; The first analog-to-digital converter and the second analog-to-digital converter are used to digitally quantize the electrical pulse signals output by the first photodetector and the second photodetector, and the quantized signal is input to the edge jitter measurement module; The edge jitter measurement module converts the quantized signals output by the first analog-to-digital converter and the second analog-to-digital converter into edge jitter measurement results, and outputs the result to the system control and data processing module; The system control and data processing module receives the digital signal of the clock data recovery module, the reference clock output by the clock splitter and the edge jitter measurement result of the edge jitter measurement module, generates the optical fiber delay line control signal and outputs the final edge jitter measurement result; The detection method of the edge jitter detector of the digital optical transmitter specifically includes the following steps: Step S0, setting the initial value of the delay amount of the optical fiber delay line to 0; Step S1, under the control of the signal slicing clock, the dual-port modulator slices the optical signal string output by the optical fiber delay line to obtain two optical pulse signals, and then passes through the dual-port modulator A port and the dual-port modulator B port respectively. Input to the first photodetector and the second photodetector for photoelectric conversion to obtain two-way electrical pulse signals; In step S2, the two circuits of electrical pulse signals are digitally quantized in the first analog-to-digital converter and the second analog-to-digital converter, respectively, to obtain two-path quantized signals; Step S3, define that the edge time of the optical signal string is ahead of the edge time of the signal slice clock as positive jitter, and the edge time of the optical signal string lags behind the edge time of the signal slice clock as negative jitter, and the edge time of the optical signal string is equal to the signal slice clock. zero jitter at the edge moment of ; The edge jitter measurement module judges the adjacent two sampling values of the first analog-to-digital converter and the second analog-to-digital converter, and obtains the edge jitter measurement result, and the two adjacent sampling values are the second time before the edge. The sampling value N _B of the analog-to-digital converter and the sampling value N _A of the first analog-to-digital converter at a moment after the edge; the specific judgment rule is: When the sampling value N _A = M of the first analog-to-digital converter, and the sampling value N _B of the second analog-to-digital converter satisfies 0<N _B <M, the edge jitter measurement result is: positive jitter on the rising edge, edge jitter value D ₁ =N _B /M, where M is the full-scale maximum value of the first analog-to-digital converter and the second analog-to-digital converter; When the sampling value of the first analog-to-digital converter N _A >0.95M, and the sampling value of the second analog-to-digital converter N _B >0, the edge jitter measurement result is: zero jitter on the rising edge, edge jitter value D ₂ =0 ; When the sampling value of the first analog-to-digital converter N _A <M and the sampling value of the second analog-to-digital converter N _B =0, the edge jitter measurement result is: negative jitter on the rising edge, edge jitter value D ₃ =(MN _A )/M; When the sampling value of the first analog-to-digital converter N _A =0, and the sampling value of the second analog-to-digital converter N _B <M, the edge jitter measurement result is: positive jitter on the falling edge, edge jitter value D ₄ =(MN _B )/M; When the sampling value of the first analog-to-digital converter N _A >0, and the sampling value of the second analog-to-digital converter N _B >0.95M, the edge jitter measurement result is: zero jitter on the falling edge, edge jitter value D ₅ =0 ; When the sampling value of the first analog-to-digital converter N _A =M, and the sampling value of the second analog-to-digital converter N _B <M, the edge jitter measurement result is: negative jitter on the falling edge, edge jitter value D ₆ =N _A /M; When the system control and data processing module detects the edge transition through the digital signal and the reference clock, the edge jitter measurement result output by the edge jitter measurement module is extracted and stored; Step S4, the system control and data processing module judges whether the optical signal string and the signal slice clock are aligned according to the edge jitter measurement result stored in step S3; When the optical signal string is aligned with the signal slice clock, steps S1~S3 are executed to start the formal measurement, and the final edge jitter measurement result is output; when all the edge jitter values in the edge jitter measurement result of the optical signal string do not satisfy When the mean value is 0, the optical signal string and the signal slice clock are not aligned. At this time, the system control and data processing module generates the fiber delay line control signal to control the delay amount of the fiber delay line. When the mean value is negative, the fiber delay line is added. When the average value is positive, reduce the delay amount of the optical fiber delay line, and repeat steps S1 to S3 until all edge jitter values in the edge jitter measurement results of the optical signal string satisfy a normal distribution with a mean value of 0. 2. The digital optical transmitter edge jitter detector according to claim 1, characterized in that, in step S2, the sampling time interval T of the first analog-to-digital converter and the second analog-to-digital converter, and the sampling rate is a clock The rate of the reference clock output by the data recovery module, T=1/ f _CLK3 , where f _CLK3 is the frequency of the signal slice clock.

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