CN113824494B - Linear light sampling-based peak value extraction method and system - Google Patents
Linear light sampling-based peak value extraction method and system Download PDFInfo
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Abstract
The invention relates to a peak value extraction method and system based on linear light sampling. The method comprises the following steps: acquiring four paths of electric pulse signals output by a balance detector by using a data acquisition card; acquiring a sampling point with the maximum absolute value in a preset period before an XI path signal; determining a first search interval, and acquiring a sampling point with the maximum absolute value in the first search interval; extracting the peak points with a set number according to the method, and further completing the extraction of the peak points for the first time; determining a second search interval according to the abscissa position of the peak point of the XI path signal, the pulse frequency and the number of sampling points in the pulse period; extracting a peak point of the XI path signal according to the sampling point with the maximum absolute value in the second search interval, and further completing the extraction of the peak point for the second time; and sequentially extracting the first peak point and the second peak point of the rest three paths of signals, thereby completing the extraction of the peak points. The invention can reduce the complexity of calculation, thereby improving the accuracy of peak value extraction and pulse frequency.
Description
Technical Field
The invention relates to the field of digital signal processing, in particular to a peak value extraction method and system based on linear light sampling.
Background
At present, with the development of mobile internet, cloud computing and electronic commerce, people have higher and higher requirements for network speed. Therefore, experts and scholars in the field of optical communication propose an all-optical sampling optical signal detection and analysis method, namely, a pulse optical sequence with low repetition frequency and narrow pulse width is utilized to sample a to-be-detected optical signal in an optical domain, then a low-bandwidth photoelectric detector and an acquisition card are utilized to complete photoelectric conversion and analog-to-digital conversion, and then digital signal processing is carried out on acquired data information, so that an eye diagram and a constellation diagram of a received signal can be detected, and a monitoring function of a low-speed acquisition card on a high-speed signal is realized.
The linear light sampling system inputs signal light and pulse laser with the frequency of about 100M generated by a passive mode-locked laser into a 90-degree frequency mixer for frequency mixing, eight ports are output through the frequency mixer, two paths of signals with the phase difference of 180 degrees in each group enter a balance detector for subtraction, the eight paths of light pulses are converted into four paths of electric pulse signals by a four-path photoelectric balance detector, the four paths of electric pulse signals can be divided into four paths of signals of XI, XQ, YI and YQ, and the signals need to be acquired from the four paths of data through sampling of a data acquisition card. The first most important point is to extract an effective sampling point of the laser pulse because other parts are not needed. In the mixing process of the laser pulse and the signal light, the information of the signal light is already collected on the peak point of the pulse, so the peak point needs to be extracted in each pulse period, namely the sampling point of the signal. And then, carrying out an algorithm processing part of orthogonal normalization, polarization demultiplexing, frequency offset estimation and phase estimation on the peak points.
In the existing method, a data acquisition card acquires data points and then intercepts a section of data points, 500000 data points are actually intercepted in an experiment, and FFT (fast Fourier transform) is firstly carried out to obtain the frequency of laser pulses. Then, a point with the maximum absolute value is selected from the points in the first period as a first peak point, the point number of one period is added to the position of the last peak point of the following peak point, and then the point with the maximum absolute value is searched from the points near the point as the peak point, so that the peak point obtained by local optimal search is kept consistent with the peak point of the original data. However, this method needs to know the number of sampling points in each pulse period, so the FFT conversion is performed on the points acquired by the ADC to determine the frequency of the laser pulse, and then the number of sampling points in each pulse period is calculated by the sampling rate and the pulse frequency. Making the modulation depth too deep by FFT variation causes peak point extraction offset and increases the complexity of the calculation.
Disclosure of Invention
The invention aims to provide a peak value extraction method and a peak value extraction system based on linear light sampling, which can reduce the complexity of calculation so as to improve the accuracy of peak value extraction and pulse frequency.
In order to achieve the purpose, the invention provides the following scheme:
a peak value extraction method based on linear light sampling comprises the following steps:
collecting four paths of electric pulse signals output by a balance detector in a linear optical sampling system by using a data acquisition card in the linear optical sampling system; the four paths of electric pulse signals are XI, XQ, YI and YQ four paths of signals;
acquiring a sampling point with the maximum absolute value in a preset period of the XI signal, and taking the sampling point with the maximum absolute value in the preset period as a first peak point of the XI signal;
determining a first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and acquiring a sampling point with the maximum absolute value in the first search interval; taking the sampling point with the maximum absolute value in the first search interval as a second peak point; replacing the first peak point of the XI path signal with a sampling point with the maximum absolute value in a first search interval as a second peak point, returning to the first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and acquiring the sampling point with the maximum absolute value in the first search interval until the peak points with the set number are extracted, thereby completing the extraction of the first peak point;
determining the pulse frequency and the number of sampling points in a pulse period according to the peak point extracted for the first time of the XI path of signals;
determining a second search interval according to the abscissa position of the peak point of the XI path signal, the pulse frequency and the number of sampling points in the pulse period; the abscissa positions of the peak points are sequentially the abscissa positions of the peak points extracted in sequence; the second search interval changes with the change of the abscissa position of the peak point;
extracting a peak point of the XI path signal according to the sampling point with the maximum absolute value in the second search interval, and further completing the extraction of the peak point for the second time;
determining the first peak point of the XQ path signal, the YI path signal and the YQ path signal according to the abscissa position of the first peak point of the XI path signal;
and according to the first peak point of the XQ path signal, the YI path signal and the YQ path signal, sequentially extracting a first peak point and a second peak point, and further extracting peak points of the XI, XQ, YI and YQ path signals.
Optionally, the acquiring, by a data acquisition card in the linear optical sampling system, four electrical pulse signals output by a balanced detector in the linear optical sampling system further includes:
setting parameters of a linear light sampling system; the parameters include: the upper and lower limits of the pulse frequency, the frequency of the laser and the speed of the data acquisition card.
Optionally, the determining a first search interval according to the abscissa position of the first peak point of the XI-path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and obtaining the sampling point with the maximum absolute value in the first search interval specifically includes:
determining a first minimum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the minimum sampling point number in each pulse period;
determining a first maximum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the maximum sampling point number in each pulse period;
a first search interval is determined based on the first minimum boundary and the first maximum boundary.
Optionally, the extracting a peak point of the XI path signal according to the sampling point with the maximum absolute value in the second search interval, so as to complete the extraction of the peak point for the second time, specifically includes:
determining two adjacent sampling points according to the extracted peak point of the second peak point;
and summing and averaging the extracted peak point of the second peak point and two adjacent sampling points.
Optionally, the extracting of the first peak point and the extracting of the second peak point are sequentially performed according to the first peak point of the XQ path signal, the YI path signal, and the YQ path signal, so as to extract peak points of the XI, XQ, YI, and YQ four paths signals, and then the method further includes:
preprocessing the extracted peak point; the pretreatment comprises the following steps: orthogonal normalization, CMA equalization processing, frequency offset estimation and phase compensation;
and reconstructing an eye diagram and drawing a constellation diagram according to the pulse frequency and the preprocessed peak point.
A linear light sampling based peak extraction system, comprising:
the electric pulse signal acquisition module is used for acquiring four paths of electric pulse signals output by a balance detector in the linear optical sampling system by using a data acquisition card in the linear optical sampling system; the four paths of electric pulse signals are XI, XQ, YI and YQ four paths of signals;
the first peak point acquisition module is used for acquiring a sampling point with the maximum absolute value in a preset period of the XI signal, and taking the sampling point with the maximum absolute value in the preset period as a first peak point of the XI signal;
the first peak point extraction module is used for determining a first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period and acquiring the sampling point with the maximum absolute value in the first search interval; taking the sampling point with the maximum absolute value in the first search interval as a second peak point; replacing the first peak point of the XI path signal with a sampling point with the maximum absolute value in a first search interval as a second peak point, returning to the first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and acquiring the sampling point with the maximum absolute value in the first search interval until the peak points with the set number are extracted, thereby completing the extraction of the first peak point;
the pulse frequency and sampling point number determining module is used for determining the pulse frequency and the sampling point number in the pulse period according to the peak point extracted for the first time of the XI path signal;
the second search interval determining module is used for determining a second search interval according to the abscissa position of the peak point of the XI path signal, the pulse frequency and the number of sampling points in the pulse period; the abscissa positions of the peak points are sequentially the abscissa positions of the peak points extracted in sequence; the second search interval changes with the change of the abscissa position of the peak point;
the second peak point extraction module is used for extracting the peak point of the XI path signal according to the sampling point with the maximum absolute value in the second search interval so as to complete the extraction of the second peak point;
the first peak point determining module is used for determining the first peak points of the XQ path signal, the YI path signal and the YQ path signal according to the abscissa position of the first peak point of the XI path signal;
and the peak point extraction completion module is used for sequentially extracting the first peak point and the second peak point according to the first peak point of the XQ path signal, the YI path signal and the YQ path signal so as to extract the peak points of the XI, XQ, YI and YQ path signals.
Optionally, the method further comprises:
the parameter setting module is used for setting parameters of the linear light sampling system; the parameters include: the upper and lower limits of the pulse frequency, the frequency of the laser and the speed of the data acquisition card.
Optionally, the first peak point extracting module specifically includes:
the first minimum boundary determining unit is used for determining a first minimum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the minimum sampling point number in each pulse period;
the second minimum boundary determining unit is used for determining a first maximum boundary according to the sum of the abscissa position of the first peak point of the XI-path signal and the maximum sampling point number in each pulse period;
a first search interval determining unit, configured to determine a first search interval according to the first minimum boundary and the first maximum boundary.
Optionally, the second peak point extracting module specifically includes:
the adjacent sampling point determining unit is used for determining two adjacent sampling points according to the extracted peak point of the second peak point;
and the average processing unit is used for summing and averaging the extracted peak point of the second peak point and two adjacent sampling points.
Optionally, the method further comprises:
the preprocessing module is used for preprocessing the extracted peak point; the pretreatment comprises the following steps: orthogonal normalization, CMA equalization processing, frequency offset estimation and phase compensation;
and the eye diagram and constellation diagram determining module is used for reconstructing an eye diagram and drawing a constellation diagram according to the pulse frequency and the preprocessed peak point.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
according to the peak value extraction method and system based on linear light sampling provided by the invention, the peak value point is extracted twice, namely rough extraction and fine extraction, so that the peak value point is accurately extracted on the premise of not using FFT (fast Fourier transform) for frequency spectrum transformation, the pulse frequency is calculated, the problem of peak value point extraction deviation caused by too deep modulation depth is avoided, the calculation complexity is greatly reduced, and the peak value extraction and the pulse frequency accuracy are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a schematic flow chart of a peak extraction method based on linear light sampling according to the present invention;
fig. 2 is a schematic diagram illustrating a principle of a peak extraction method based on linear light sampling according to the present invention;
FIG. 3 is a schematic diagram of a linear light sampling system;
FIG. 4 is a flow chart of data signal processing;
FIG. 5 is a schematic diagram of averaging around a peak point to remove high frequency noise;
FIG. 6 is a schematic diagram of finding a next peak point based on a previous peak point;
FIG. 7 is a schematic diagram of the exact extraction of peak points;
fig. 8 is an eye diagram and constellation diagram illustration;
fig. 9 is a schematic structural diagram of a peak extraction system based on linear light sampling according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a peak value extraction method and a peak value extraction system based on linear light sampling, which can reduce the complexity of calculation so as to improve the accuracy of peak value extraction and pulse frequency.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic flow chart of a peak extraction method based on linear light sampling provided by the present invention, fig. 2 is a schematic principle diagram of a peak extraction method based on linear light sampling provided by the present invention, and as shown in fig. 1 and fig. 2, the peak extraction method based on linear light sampling provided by the present invention includes:
s101, collecting four paths of electric pulse signals output by a balance detector in a linear optical sampling system by using a data acquisition card in the linear optical sampling system; the four paths of electric pulse signals are XI, XQ, YI and YQ four paths of signals;
the specific implementation process of data acquisition on the QPSK signal is as follows:
a laser with the center wavelength of 1560nm outputs a path of laser, and because the spectral width of the laser in an experiment is 10-15nm, the wider the spectrum is, the worse the coherence with signal light is, and interference signals with the center wavelength not of 1560nm can be coherent, the power of laser pulses is reduced to about 3.2dbm by passing through a 6nm bandwidth spectral filter and externally connecting an optical attenuator, and the laser pulses enter the local oscillator light input end of a mixer. The pulse signals are output to a four-way balance detector through coherent mixing. The optical path differences of the four-path balance detector are the same by manually adjusting the attenuation, and the four-path waveforms can be seen to be almost completely overlapped in an oscilloscope. And modulating a path of 16GBoud QPSK signal at a signal transmitting end, loading the QPSK signal on continuous laser with the central wavelength of 1560nm, and transmitting the QPSK signal to a signal light input end of the frequency mixer through an optical fiber channel with the power of about 2.5 dbm. The two signals are coherently mixed in the mixer, and the modulation depth of the signals is approximately 2/3 of the pulse light amplitude, which can be roughly seen in an oscilloscope. And data acquisition is carried out by using a data acquisition card.
As shown in fig. 3, the linear optical sampling system includes a frequency tunable passive mode-locked laser, a spectral filter that can be controlled by a computer, a 90-degree mixer, four balanced detectors, a data acquisition card, an oscilloscope, and a QPSK signal generator with adjustable rate. The laser outputs 1560nm of pulse laser with stable and adjustable frequency, and the pulse laser is used for mixing and sampling the signal light. The filter is used for filtering redundant spectral components in the laser spectrum, and can effectively improve the coherence of laser pulses. The 90-degree mixer is a passive device with two ports for input and eight ports for output, a polarizing film is arranged in the 90-degree mixer, the signal light is divided into X and Y paths, wherein the X path and the Y path are respectively divided into four optical signals with phases of 0 degree, 90 degrees, 180 degrees and 270 degrees, the eight signals are respectively input into a balanced detector in pairs, and the signals with the phase difference of 180 degrees are subtracted to obtain two paths of signals I and Q, so four paths of signals XI, XQ, YI and YQ are obtained through the balanced detector. The data acquisition card is used for acquisition, so that discrete data points can be obtained for digital signal processing. The digital signal processing part is constructed as shown in fig. 4. The collected data points are subjected to peak value extraction processing firstly, peak value points in each pulse period are extracted, and new data points formed by the peak value points are the data points containing original signal information. Therefore, the peak value extraction part links the hardware receiving part and the software processing part of the linear light sampling system, which is a very important link. After the peak value extraction, the repetition frequency of the pulse can be calculated, and important parameters are provided for the following software synchronization. The peak value extraction is followed by the quadrature normalization, because a 90 ° mixer usually has a certain phase mismatch, so that the output of the IQ two paths is not exactly 90 °, and the complete orthogonality of the signals is lost. And then the signal distortion caused by the birefringence effect is eliminated through CMA equalization. And then carrying out frequency offset estimation and phase estimation to realize carrier recovery, and then carrying out software synchronization by using the obtained pulse frequency to realize reconstruction of an eye diagram and drawing a constellation diagram.
Before S101, the method further includes:
setting parameters of a linear light sampling system; the parameters include: the upper and lower limits of the pulse frequency, the frequency of the laser and the speed of the data acquisition card.
As a specific example, the laser used in the experiment was a laser whose frequency was adjustable in the range of 95Mhz to 100Mhz, and thus the upper limit of the pulse frequency was set to 1e8 and the lower limit was set to 9.5e 7. The speed of the acquisition card is set to be 12.5G/S, the minimum number N of sampling points in each pulse period can be obtained by dividing the upper limit and the lower limit of the pulse frequency by the acquisition speed and performing downward integrationminAnd maximum number of sampling pointsNmax. And setting the number M of peak points, and dividing the maximum sampling point of each pulse period by the length of the signal to obtain the whole, wherein a part of the peak points at the rearmost of the signal can be abandoned by using the maximum sampling point number finally, so that the process of searching the peak points can not exceed the length of the signal. A parameter W is set for searching the maximum value of the absolute value in the set period before XI, where W is set to 5.
S102, acquiring a sampling point with the maximum absolute value in a preset period of the XI signal, and taking the sampling point with the maximum absolute value in the preset period as a first peak point of the XI signal; the peak value extraction error caused by too small pulse absolute value in one or two periods before the data point is avoided, and the first peak value point is ensured to be the sharp peak point of the laser pulse.
S103, according to the abscissa position of the first peak point of the XI path signal and the minimum number N of sampling points in each pulse periodminAnd the maximum number of sampling points NmaxDetermining a first search interval, and acquiring a sampling point with the maximum absolute value in the first search interval; taking the sampling point with the maximum absolute value in the first search interval as a second peak point; replacing the first peak point of the XI path signal with a sampling point with the maximum absolute value in a first search interval as a second peak point, returning to the first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and acquiring the sampling point with the maximum absolute value in the first search interval until the peak points with the set number are extracted, thereby completing the extraction of the first peak point;
s103 specifically comprises the following steps:
determining a first minimum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the minimum sampling point number in each pulse period;
determining a first maximum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the maximum sampling point number in each pulse period;
a first search interval is determined based on the first minimum boundary and the first maximum boundary.
As shown in fig. 6, the point with the largest absolute value is found in the interval range, which is the second peak point. This is cycled through until a specified number of peak points are all found, which is the first peak extraction, which is also a coarse peak extraction.
S104, determining the pulse frequency and the number of sampling points in a pulse period according to the peak point extracted for the first time of the XI path signal; the data point interval between two adjacent peak points can be recorded in the process of finding the peak point, and when all the peak point information is found and all the intervals are averaged, the number N of sampling points in one pulse period can be obtained. The frequency of the laser pulse can be calculated by the sampling rate of the acquisition card and the number of points in one pulse period. N is the ADC sampling rate/pulse frequency.
S105, determining a second search interval according to the abscissa position of the peak point of the XI-path signal, the pulse frequency and the number of sampling points in the pulse period; the abscissa positions of the peak points are sequentially the abscissa positions of the peak points extracted in sequence; the second search interval changes with the change of the abscissa position of the peak point;
s105 specifically comprises the following steps:
an error range m is set to 0.02. The peak extraction is performed after the first peak point, but the search range for the peak becomes smaller, the first time (N)min,Nmax) And searching for the peak point in the second time, adding (1-m) × N and (1+ m) × N after the first peak point, and searching for the point with the maximum absolute value in the range, so as to circularly obtain all the peak points. Because the search range of the first peak extraction is large, there will be an error in extracting individual peak points, and after the second peak extraction, all peak points are correctly extracted, this time, the fine peak extraction.
S106, extracting a peak point of the XI path signal according to the sampling point with the maximum absolute value in the second search interval, and further completing the extraction of the peak point for the second time;
s106 specifically comprises:
determining two adjacent sampling points according to the extracted peak point of the second peak point;
and summing and averaging the extracted peak point of the second peak point and two adjacent sampling points.
As shown in fig. 5, a local averaging is used in the second peak extraction process to obtain the high-frequency noise, and as shown in fig. 5, a point is respectively obtained on the left and right adjacent to each peak point, and the averaging of the three points can effectively reduce the influence of the high-frequency noise on the peak extraction.
S107, determining the first peak point of the XQ path signal, the YI path signal and the YQ path signal according to the abscissa position of the first peak point of the XI path signal; the respective first peak point is found nearby with the point as the reference in the three-way information, because the four-way data is almost synchronous, the peak point of the three-way information will definitely appear nearby the first peak point of the XI-way information. And repeating the steps after the first peak point is found, and carrying out two-step peak extraction. This ensures that the eye diagram and constellation can be recovered from the four paths of information.
And S108, sequentially extracting a first peak point and a second peak point according to the first peak points of the XQ path signal, the YI path signal and the YQ path signal, and further extracting peak points of the XI, XQ, YI and YQ path signals, wherein the peak points are shown in FIG. 7.
After S108, further comprising:
preprocessing the extracted peak point; the pretreatment comprises the following steps: orthogonal normalization, CMA equalization processing, frequency offset estimation and phase compensation;
and reconstructing an eye diagram and drawing a constellation diagram according to the pulse frequency and the preprocessed peak point. As shown in fig. 8, the eyes are found to be open clearly, four starballs are found clearly through the constellation diagram drawn by the eye diagram, and the EVM value can be reduced to about 0.15, which is good.
Fig. 9 is a schematic structural diagram of a peak extraction system based on linear light sampling provided by the present invention, and as shown in fig. 9, the peak extraction system based on linear light sampling provided by the present invention includes:
an electrical pulse signal acquisition module 901, configured to acquire four electrical pulse signals output by a balanced detector in a linear optical sampling system by using a data acquisition card in the linear optical sampling system; the four paths of electric pulse signals are XI, XQ, YI and YQ four paths of signals;
a first peak point obtaining module 902, configured to obtain a sampling point with a maximum absolute value in a preset period of the XI-path signal, and use the sampling point with the maximum absolute value in the preset period as a first peak point of the XI-path signal;
a first peak point extraction module 903, configured to determine a first search interval according to an abscissa position of a first peak point of the XI-path signal, a minimum sampling point number and a maximum sampling point number in each pulse period, and obtain a sampling point with a maximum absolute value in the first search interval; taking the sampling point with the maximum absolute value in the first search interval as a second peak point; replacing the first peak point of the XI path signal with a sampling point with the maximum absolute value in a first search interval as a second peak point, returning to the first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and acquiring the sampling point with the maximum absolute value in the first search interval until the peak points with the set number are extracted, thereby completing the extraction of the first peak point;
a pulse frequency and sampling point number determining module 904, configured to determine a pulse frequency and a sampling point number in a pulse period according to a peak point extracted for the first time of the XI-path signal;
a second search interval determining module 905, configured to determine a second search interval according to an abscissa position of a peak point of the XI-path signal, the pulse frequency, and a number of sampling points in a pulse period; the abscissa positions of the peak points are sequentially the abscissa positions of the peak points extracted in sequence; the second search interval changes with the change of the abscissa position of the peak point;
a second peak point extraction module 906, configured to extract a peak point of the XI-path signal according to the sampling point with the largest absolute value in the second search interval, so as to complete extraction of the second peak point;
a first peak point determining module 907, configured to determine a first peak point of the XQ channel signal, the YI channel signal, and the YQ channel signal according to an abscissa position of the first peak point of the XI channel signal;
and a peak point extraction completion module 908, configured to sequentially perform first peak point extraction and second peak point extraction according to the first peak point of the XQ path signal, the YI path signal, and the YQ path signal, so as to extract peak points of the XI, XQ, YI, and YQ four paths of signals.
The invention provides a peak value extraction system based on linear light sampling, which further comprises:
the parameter setting module is used for setting parameters of the linear light sampling system; the parameters include: the upper and lower limits of the pulse frequency, the frequency of the laser and the speed of the data acquisition card.
The first peak point extraction module 903 specifically includes:
the first minimum boundary determining unit is used for determining a first minimum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the minimum sampling point number in each pulse period;
the second minimum boundary determining unit is used for determining a first maximum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the maximum sampling point number in each pulse period;
a first search interval determining unit, configured to determine a first search interval according to the first minimum boundary and the first maximum boundary.
The second peak point extracting module 906 specifically includes:
the adjacent sampling point determining unit is used for determining two adjacent sampling points according to the extracted peak point of the second peak point;
and the average processing unit is used for summing and averaging the extracted peak point of the second peak point and two adjacent sampling points.
The invention provides a peak value extraction system based on linear light sampling, which further comprises:
the preprocessing module is used for preprocessing the extracted peak point; the pretreatment comprises the following steps: orthogonal normalization, CMA equalization processing, frequency offset estimation and phase compensation;
and the eye diagram and constellation diagram determining module is used for reconstructing an eye diagram and drawing a constellation diagram according to the pulse frequency and the preprocessed peak point.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the description of the method part.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A peak value extraction method based on linear light sampling is characterized by comprising the following steps:
collecting four paths of electric pulse signals output by a balance detector in a linear optical sampling system by using a data acquisition card in the linear optical sampling system; the four paths of electric pulse signals are XI, XQ, YI and YQ four paths of signals;
acquiring a sampling point with the maximum absolute value in a preset period of the XI signal, and taking the sampling point with the maximum absolute value in the preset period as a first peak point of the XI signal;
determining a first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and acquiring a sampling point with the maximum absolute value in the first search interval; taking the sampling point with the maximum absolute value in the first search interval as a second peak point; replacing the first peak point of the XI path signal with a sampling point with the maximum absolute value in the first search interval, namely a second peak point, returning to the step of determining the first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and acquiring the sampling point with the maximum absolute value in the first search interval until the peak points with the set number are extracted, thereby completing the extraction of the first peak point;
determining the pulse frequency and the number of sampling points in a pulse period according to the peak point extracted for the first time of the XI path of signals;
determining a second search interval according to the abscissa position of the peak point of the XI path signal, the pulse frequency and the number of sampling points in the pulse period; the abscissa positions of the peak points are sequentially the abscissa positions of the peak points extracted in sequence; the second search interval changes with the change of the abscissa position of the peak point;
extracting a peak point of the XI path signal according to the sampling point with the maximum absolute value in the second search interval, and further completing the extraction of the peak point for the second time;
determining the first peak point of the XQ path signal, the YI path signal and the YQ path signal according to the abscissa position of the first peak point of the XI path signal;
and according to the first peak point of the XQ path signal, the YI path signal and the YQ path signal, sequentially extracting the first peak point and the second peak point, and further extracting the peak points of the XI, XQ, YI and YQ path signals.
2. The method according to claim 1, wherein the four electrical pulse signals output by the balanced detector in the linear optical sampling system are collected by a data acquisition card in the linear optical sampling system, and the method further comprises:
setting parameters of a linear light sampling system; the parameters include: the upper and lower limits of the pulse frequency, the frequency of the laser and the speed of the data acquisition card.
3. The method according to claim 1, wherein the determining a first search interval according to an abscissa position of a first peak point of the XI-path signal, a minimum sampling point number and a maximum sampling point number in each pulse period, and obtaining a sampling point with a maximum absolute value in the first search interval specifically comprises:
determining a first minimum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the minimum sampling point number in each pulse period;
determining a first maximum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the maximum sampling point number in each pulse period;
a first search interval is determined based on the first minimum boundary and the first maximum boundary.
4. The method according to claim 1, wherein the extracting of the peak point of the XI-path signal according to the sampling point with the maximum absolute value in the second search interval is performed to further complete the second extraction of the peak point, and specifically includes:
determining two adjacent sampling points according to the extracted peak point of the second peak point;
and summing and averaging the extracted peak point of the second peak point and two adjacent sampling points.
5. The method as claimed in claim 1, wherein the first peak point extraction and the second peak point extraction are sequentially performed according to a first peak point of the XQ channel signal, the YI channel signal, and the YQ channel signal, so as to extract peak points of the XI, XQ, YI, and YQ channels of signals, and the method further comprises:
preprocessing the extracted peak point; the pretreatment comprises the following steps: orthogonal normalization, CMA equalization processing, frequency offset estimation and phase compensation;
and reconstructing an eye diagram and drawing a constellation diagram according to the pulse frequency and the preprocessed peak point.
6. A peak extraction system based on linear light sampling, comprising:
the electric pulse signal acquisition module is used for acquiring four paths of electric pulse signals output by a balance detector in the linear optical sampling system by using a data acquisition card in the linear optical sampling system; the four paths of electric pulse signals are XI, XQ, YI and YQ four paths of signals;
the first peak point acquisition module is used for acquiring a sampling point with the maximum absolute value in a preset period of the XI signal, and taking the sampling point with the maximum absolute value in the preset period as a first peak point of the XI signal;
the first peak point extraction module is used for determining a first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period and acquiring the sampling point with the maximum absolute value in the first search interval; taking the sampling point with the maximum absolute value in the first search interval as a second peak point; replacing the first peak point of the XI path signal with a sampling point with the maximum absolute value in the first search interval, namely a second peak point, returning to the step of determining the first search interval according to the abscissa position of the first peak point of the XI path signal, the minimum sampling point number and the maximum sampling point number in each pulse period, and acquiring the sampling point with the maximum absolute value in the first search interval until the peak points with the set number are extracted, thereby completing the extraction of the first peak point;
the pulse frequency and sampling point number determining module is used for determining the pulse frequency and the sampling point number in the pulse period according to the peak point extracted for the first time of the XI path signal;
the second search interval determining module is used for determining a second search interval according to the abscissa position of the peak point of the XI path signal, the pulse frequency and the number of sampling points in the pulse period; the abscissa positions of the peak points are sequentially the abscissa positions of the peak points extracted in sequence; the second search interval changes with the change of the abscissa position of the peak point;
the second peak point extraction module is used for extracting the peak point of the XI path signal according to the sampling point with the maximum absolute value in the second search interval so as to complete the extraction of the second peak point;
the first peak point determining module is used for determining the first peak points of the XQ path signal, the YI path signal and the YQ path signal according to the abscissa position of the first peak point of the XI path signal;
and the peak point extraction completion module is used for sequentially extracting the first peak point and the second peak point according to the first peak point of the XQ path signal, the YI path signal and the YQ path signal so as to extract the peak points of the XI, XQ, YI and YQ path signals.
7. The linear light sampling based peak extraction system of claim 6, further comprising:
the parameter setting module is used for setting parameters of the linear light sampling system; the parameters include: the upper and lower limits of the pulse frequency, the frequency of the laser and the speed of the data acquisition card.
8. The linear light sampling based peak extraction system according to claim 6, wherein the first peak point extraction module specifically includes:
a first minimum boundary determining unit, configured to determine a first minimum boundary according to a sum of an abscissa position of a first peak point of the XI-path signal and a minimum number of sampling points in each pulse period;
the second minimum boundary determining unit is used for determining a first maximum boundary according to the sum of the abscissa position of the first peak point of the XI path signal and the maximum sampling point number in each pulse period;
a first search interval determining unit, configured to determine a first search interval according to the first minimum boundary and the first maximum boundary.
9. The linear light sampling based peak extraction system according to claim 6, wherein the second peak point extraction module specifically includes:
the adjacent sampling point determining unit is used for determining two adjacent sampling points according to the extracted peak point of the second peak point;
and the average processing unit is used for summing and averaging the extracted peak point of the second peak point and two adjacent sampling points.
10. The linear light sampling based peak extraction system of claim 6, further comprising:
the preprocessing module is used for preprocessing the extracted peak point; the pretreatment comprises the following steps: orthogonal normalization, CMA equalization processing, frequency offset estimation and phase compensation;
and the eye diagram and constellation diagram determining module is used for reconstructing an eye diagram and drawing a constellation diagram according to the pulse frequency and the preprocessed peak point.
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