CN114978319A - Signal processing method, network device, and storage medium - Google Patents
Signal processing method, network device, and storage medium Download PDFInfo
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- H04B10/503—Laser transmitters
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- H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
- H04B10/2513—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to chromatic dispersion
- H04B10/25137—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to chromatic dispersion using pulse shaping at the transmitter, e.g. pre-chirping or dispersion supported transmission [DST]
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Abstract
The invention relates to the technical field of optical fiber communication, in particular to a signal processing method, network equipment and a storage medium, wherein the signal processing method comprises the following steps: acquiring a signal to be input of a laser; and according to a preset signal preprocessing strategy, preprocessing the signal to be input for eliminating chirp to obtain a target signal, and inputting the target signal into the laser. According to the technical scheme of the embodiment of the invention, the chirp elimination preprocessing is carried out on the signal to be input according to the signal preprocessing strategy, so that the chirp in the optical signal output by the laser can be eliminated or reduced, and the transmission performance of the optical fiber communication link is improved.
Description
Technical Field
The present invention relates to the field of optical fiber communication technologies, and in particular, to a signal processing method, a network device, and a storage medium.
Background
In fiber optic communication links, optical pulses are transmitted with chirp. The chirp is mainly caused by dynamic change of refractive index of the medium due to dynamic modulation of the electrical signal, so that the phase of the optical signal propagating in the medium also changes dynamically, which is reflected as dynamic change of the frequency of the optical signal. In an optical fiber communication link, chirp may reduce the transmission performance of the optical fiber communication link, and therefore, how to eliminate or reduce chirp in an optical signal becomes an urgent problem to be solved.
Disclosure of Invention
Embodiments of the present invention provide a signal processing method, a network device, and a storage medium, where chirp removal preprocessing is performed on a signal to be input according to a signal preprocessing policy, so that chirp in an optical signal output by a laser can be removed or reduced, and transmission performance of an optical fiber communication link is improved.
In a first aspect, an embodiment of the present invention provides a signal processing method, which is applied in a network device, and the method includes: acquiring a signal to be input of a laser; and according to a preset signal preprocessing strategy, preprocessing the signal to be input for eliminating chirp to obtain a target signal, and inputting the target signal into the laser.
In a second aspect, an embodiment of the present invention further provides a network device, where the network device includes an optical line terminal or an optical network unit, where the optical line terminal or the optical network unit includes a processor and a memory; the memory is used for storing programs; the processor is used for calling the program in the memory to realize the signal processing method.
In a third aspect, the present invention also provides a storage medium for readable storage, where the storage medium stores one or more programs, and the one or more programs are executable by one or more processors to implement the signal processing method as described above.
The embodiment of the invention discloses a signal processing method, network equipment and a storage medium, wherein the signal to be input of a laser is acquired, so that the signal to be input can be subjected to pre-processing for eliminating chirp before the signal to be input is input into the laser; the chirp elimination preprocessing is carried out on the signal to be input according to a preset signal preprocessing strategy, the obtained target signal is input into the laser, the chirp in the optical signal output by the laser can be eliminated or reduced, and the transmission performance of the optical fiber communication link is improved.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an optical fiber communication link according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a network device according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a network device according to an embodiment of the present invention;
FIG. 4 is a schematic flow chart diagram of a signal processing method according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a waveform of a signal to be input according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a waveform of a filtered target signal provided by an embodiment of the present invention;
FIG. 7 is a schematic representation of a waveform of another filtered target signal provided by an embodiment of the present invention;
fig. 8 is a schematic flow chart of a sub-step of performing filtering cancellation processing on a signal to be input according to an embodiment of the present invention;
fig. 9 is a schematic diagram of filtering a signal to be input according to an embodiment of the present invention;
fig. 10 is a schematic flow chart of a sub-step of adjusting a power value of a signal to be input according to an embodiment of the present invention;
fig. 11 is a schematic flow chart of another sub-step of adjusting the power value of a signal to be input according to an embodiment of the present invention;
fig. 12 is a spectrum diagram of a signal to be input according to an embodiment of the present invention;
FIG. 13 is a schematic flow chart diagram of sub-steps of buffering a signal to be input according to an embodiment of the present invention;
fig. 14 is a schematic diagram of a waveform for buffering a signal to be input according to an embodiment of 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 some, not all, embodiments of the present invention. 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 flow diagrams depicted in the figures are merely illustrative and do not necessarily include all of the elements and operations/steps, nor do they necessarily have to be performed in the order depicted. For example, some operations/steps may be decomposed, combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.
It is to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should also be understood that the term "and/or" as used in this specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items and includes such combinations.
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the following description, suffixes such as "module", "part", or "unit" used to denote elements are used only for facilitating the explanation of the present invention, and have no peculiar meaning in itself. Thus, "module", "component" or "unit" may be used mixedly.
Embodiments of the present invention provide a signal processing method, a network device, and a storage medium. The signal processing method can be applied to network equipment, and can eliminate or reduce chirp in an optical signal output by a laser and improve the transmission performance of an optical fiber communication link by preprocessing the signal to be input according to a signal preprocessing strategy to eliminate the chirp.
It should be noted that the signal processing method in the embodiment of the present application may be applied to a Passive Optical Network (PON). Illustratively, the Network device may be an Optical Line Terminal (OLT) or an Optical Network Unit (ONU) in a passive Optical Network.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an optical fiber communication link according to an embodiment of the present invention. As shown in fig. 1, the optical fiber communication link includes a transmitting end, an optical fiber, and a receiving end. Wherein, the transmitting end can be a network device; the receiving end may include a photodetector and a low pass filter.
Illustratively, the optical line terminal or the optical network unit may transmit the optical signal to an optical fiber, which is transmitted to the receiving end.
Referring to fig. 2, fig. 2 is a schematic diagram of a network device according to an embodiment of the present invention. As shown in fig. 2, the network device includes a level signal generator, a low pass filter, and a laser. Wherein the low pass filter is present between the level signal generator and the directly modulated laser, which may be a directly modulated laser.
The low-pass filter is an electronic filter device that allows signals below a cutoff frequency to pass through but does not allow signals above the cutoff frequency to pass through. Illustratively, the low pass filter may include, but is not limited to, a butterworth filter, a chebyshev filter, and the like.
For example, the level signal generator may generate a current signal, which is filtered by a low-pass filter and then input into the direct modulation laser; the filtered current signal is converted to an optical signal by a directly modulated laser.
It should be noted that, after the current signal generated by the level signal generator is input to the direct modulation laser, the optical signal output by the direct modulation laser has chirp, and therefore, the current signal needs to be preprocessed in advance to remove or reduce the chirp in the optical signal.
Referring to fig. 3, fig. 3 is a schematic structural diagram of a network device according to an embodiment of the present invention. The network device 10 may include a processor 11 and a memory 12, wherein the processor 11 and the memory 12 may be connected by a bus, such as an I2C (Inter-integrated Circuit) bus or any suitable bus.
The memory 12 may include, among other things, a nonvolatile storage medium and an internal memory. The non-volatile storage medium may store an operating system and a computer program. The computer program comprises program instructions which, when executed, cause a processor to perform any of the signal processing methods.
Processor 11 is used to provide computing and control capabilities, among other things, to support the operation of the overall network device 10.
In an embodiment, the processor 11 is configured to run a computer program stored in the memory 12, and when executing the computer program, to implement the following steps:
acquiring a signal to be input of a laser; and according to a preset signal preprocessing strategy, preprocessing the signal to be input for eliminating chirp to obtain a target signal, and inputting the target signal into the laser.
In one embodiment, the network device 10 includes a level signal generator; when the processor 11 is used for acquiring the signal to be input of the laser, the processor is configured to implement:
receiving the digital signal generated by the level signal generator; and performing digital-to-analog conversion on the digital signal to obtain the signal to be input.
In one embodiment, there is a filter between the level signal generator and the laser; the processor 11 is configured to, when implementing preprocessing for removing chirp on the signal to be input according to a preset signal preprocessing policy to obtain a target signal, implement:
if the signal preprocessing strategy is to perform filtering cancellation processing on the signal to be input, determining a transfer function corresponding to the filter, wherein the transfer function is used for filtering the signal; exchanging positions of a zero point and a pole of the transfer function to obtain an inverse transfer function corresponding to the transfer function; filtering the signal to be input according to the inverse transformation transfer function to obtain a filtered signal corresponding to the signal to be input; and filtering the filtered signal according to the transfer function to obtain the target signal, wherein the target signal is a square wave signal, and an optical signal output by the square wave signal after being input into the laser does not contain chirp.
In one embodiment, the processor 11 is configured to, when performing pre-processing for removing chirp on the signal to be input according to a preset signal pre-processing policy, implement:
and when the signal preprocessing strategy is to adjust the power value of the signal to be input, adjusting the power value of the signal to be input to meet a preset power condition so as to eliminate phase change caused by chirp in the optical signal output by the laser.
In one embodiment, the signal to be input comprises a first level signal and a second level signal; when the processor 11 is used for adjusting the power value of the signal to be input to meet the preset power condition, the processor is configured to implement:
collecting a first power value of the first level signal and a second power value of the second level signal; and increasing the first power value and the second power value so that the first power value and the second power value are both larger than a preset first power threshold.
In one embodiment, the processor 11, after implementing acquiring the first power value of the first level signal and the second power value of the second level signal, is further configured to implement:
determining a first product between a transient chirp coefficient and a steady-state chirp coefficient; and adjusting the first power value and the second power value according to a preset modulation coefficient, so that a second product between the adjusted first power value and the first product is equal to a preset second power threshold, and a third product between the adjusted second power value and the first product is equal to the second power threshold.
In one embodiment, the processor 11, in enabling determining the first product between the transient chirp coefficient and the steady-state chirp coefficient, is configured to enable:
acquiring a first frequency offset value of the first level signal and a second frequency offset value of the second level signal; determining the first product between the transient chirp coefficient and the steady-state chirp coefficient according to the first power value and the first frequency offset value or the second power value and the second frequency offset value.
In an embodiment, when implementing a pre-processing for removing chirp on the signal to be input according to a preset signal pre-processing policy to obtain a target signal, the processor 11 is configured to implement:
when the signal preprocessing strategy is to buffer the signal to be input, determining rising edge processing time, falling edge processing time and amplitude limiting value; and performing advanced rising processing on the rising edge of the signal to be input according to the rising edge processing time and the amplitude limiting value, and performing overshoot processing on the falling edge of the signal to be input according to the falling edge processing time and the amplitude limiting value to obtain the target signal, wherein the time of the rising edge and the time of the falling edge of the target signal are prolonged to eliminate phase change caused by chirp in the optical signal output by the laser.
In one embodiment, there is a filter between the level signal generator and the laser; the processor 11, before effecting the input of the target signal into the laser, is further configured to effect:
and filtering the target signal through the filter to obtain the filtered target signal.
In one embodiment, the processor 11, when effecting input of the target signal into the laser, is adapted to effect:
and inputting the filtered target signal into the laser.
The Processor 11 may be a Central Processing Unit (CPU), or may be other general-purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA) or other Programmable logic device, a discrete Gate or transistor logic device, a discrete hardware component, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
Some embodiments of the invention are described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
As shown in fig. 4, fig. 4 is a schematic flow chart of a signal processing method according to an embodiment of the present invention. The signal processing method is applied to network equipment, and can eliminate or reduce chirp in an optical signal output by a laser and improve the transmission performance of an optical fiber communication link by carrying out chirp elimination pretreatment on a signal to be input according to a signal pretreatment strategy. The signal processing method includes step S101 and step S102.
Step 101, obtaining a signal to be input of a laser.
In an embodiment of the invention, the network device comprises a level signal generator, a low-pass filter and a directly modulated laser, and the signal to be input can be generated by the level signal generator. The signal to be input is a current signal.
In some embodiments, acquiring a signal to be input to the laser may include: receiving a digital signal generated by a level signal generator; and D/A conversion is carried out on the digital signal to obtain a signal to be input.
Illustratively, the level signal generator may generate a digital signal of 0/1 level; and then, performing digital-to-analog conversion on the digital signal through a digital-to-analog converter to obtain an analog signal, namely a signal to be input.
Referring to fig. 5, fig. 5 is a schematic diagram of a waveform of a signal to be input according to an embodiment of the present invention. As shown in fig. 5, the signal to be input is a square wave signal of 0/1 level before passing through the low pass filter.
In the embodiment of the invention, after the digital signal is subjected to digital-to-analog conversion to obtain a signal to be input, the signal to be input needs to be filtered through a low-pass filter to obtain a target signal, and then the target signal is input into the direct modulation laser.
By acquiring the signal to be input of the laser, preprocessing for eliminating chirp can be carried out on the signal to be input subsequently, and the chirp of an optical signal generated after a target signal is input into the laser is avoided, so that the communication quality of the optical signal is not influenced.
Referring to fig. 6 and 7, fig. 6 is a schematic diagram of a waveform of a filtered target signal according to an embodiment of the present invention, and fig. 7 is a schematic diagram of a waveform of another filtered target signal according to an embodiment of the present invention. In fig. 6 and 7, a signal to be input is filtered, and a target signal obtained by filtering is input into a laser to generate an optical signal.
It is understood that the chirp may include transient chirp and steady-state chirp. The change of current generated by transient chirp on the laser causes the change of carrier concentration in the resonant cavity, so that the frequency of the laser fluctuates; the steady chirp is determined by the magnitude of the current signal, which is present throughout the current signal period, and the induced frequency offset is proportional to the magnitude of the current signal.
It should be noted that, in the embodiment of the present invention, the signal processing method mainly performs a pre-processing of removing chirp on the current-removal signal, so as to remove or reduce transient chirp in the optical signal output by the laser; the embodiments of the present invention will explain how to eliminate or reduce the transient chirp by combining the characteristics of the transient chirp in the current.
Step S102, according to a preset signal preprocessing strategy, preprocessing for eliminating chirp is carried out on the signal to be input, a target signal is obtained, and the target signal is input into the laser.
For example, the preset signal preprocessing strategy may include at least one of the following: carrying out filtering offset processing on a signal to be input; adjusting the power value of a signal to be input; and carrying out buffering processing on the signal to be input.
It should be noted that, the filtering cancellation processing on the signal to be input refers to canceling the filtering action of the low-pass filter, so that the target signal filtered by the low-pass filter is consistent with the signal to be input before filtering, and both are square wave signals with 0/1 levels; because transient chirp only has the jump of the square wave signal, the influence of the transient chirp can be eliminated to the maximum extent. Adjusting the power value of the signal to be input means adjusting the power value of the 0/1 level of the signal to be input to meet a preset condition so as to eliminate the phase change of the optical signal caused by the transient chirp. The buffering processing of the signal to be input means that the rising edge time and the falling edge time of the signal to be input are prolonged, and the obtained target signal can be quickly restored to a stable state, so that the transient chirp is weakened.
In the embodiment of the present invention, how to perform the preprocessing for removing chirp on the input signal will be described in detail based on different signal preprocessing strategies.
Referring to fig. 8, fig. 8 is a schematic flowchart illustrating sub-steps of filtering and cancelling a signal to be input according to an embodiment of the present invention, and specifically includes the following steps S201 to S204.
Step S201, if the signal preprocessing strategy is to perform filtering cancellation processing on the signal to be input, determining a transfer function corresponding to the filter, where the transfer function is used to filter the signal.
For example, the frequency response characteristic of the low-pass filter can be measured by a spectrometer, and the inverse function of the low-pass filter is obtained in the frequency domain, that is, the inverse transfer function of the transfer function is obtained.
The zero and the pole of the transfer function can be obtained by determining the transfer function corresponding to the low-pass filter, so that the position exchange of the zero and the pole of the transfer function can be realized, and the inverse transfer function corresponding to the transfer function can be obtained.
And step S202, interchanging the positions of the zero and the pole of the transfer function to obtain an inverse transfer function corresponding to the transfer function.
Illustratively, the positions of the zero z and the pole p of the transfer function of the low-pass filter can be interchanged by a zp2tf function, the transfer function corresponding to the inverse transfer function being:
exemplarily, the representation of the low-pass filter after interchanging the positions of the zero z and the pole p is [ b ', a' ] — zp2tf (p, z, 1); where a 'and b' are the new time-domain tap coefficients, a 'is the vector coefficient at the denominator, and b' is the vector coefficient at the numerator.
And performing position interchange on a zero point and a pole of the transfer function to obtain an inverse transformation transfer function corresponding to the transfer function, so that the signal to be input is sequentially filtered according to the inverse transformation transfer function and the transfer function, and the target signal obtained by filtering is consistent with the signal to be input before filtering.
And step S203, filtering the signal to be input according to the inverse transformation transfer function to obtain a filtered signal corresponding to the signal to be input.
Referring to fig. 9, fig. 9 is a schematic diagram illustrating a filtering process performed on a signal to be input according to an embodiment of the present invention. As shown in FIG. 9, the signal to be input at node 1 is denoted as s 1 The filtered signal at node 1.1 is denoted s 1.1 The target signal at node 2 is denoted as s 2 Wherein s is 2 ＝filter(b,a,s 1.1 )。
Illustratively, the signal to be input is filtered according to an inverse transform transfer function, and the obtained filtered signal is s 1.1 ＝filter(b′,a′,s 1 )。
Step S204, filtering the filtering signal according to the transfer function to obtain the target signal, wherein the target signal is a square wave signal, and an optical signal output by the square wave signal after being input into the laser does not contain chirp.
Illustratively, the filtering process is performed on the filtered signal according to a transfer function, and the obtained target signal is s 2 ＝filter(b,a,s 1.1 ). According to the formula s 1.1 ＝filter(b′,a′,s 1 ) And the formula s 2 ＝filter(b,a,s 1.1 ) The signal s to be input can be obtained 1 With the target signal s 2 The same is true.
In the embodiment of the present invention, the signal to be input is a square wave signal, and the target signal is also a square wave signal.
The signal to be input is filtered according to the inverse transformation transfer function, and the filtered signal is secondarily filtered through the transfer function, so that the obtained target signal is consistent with the signal to be input before filtering and is a square wave signal, the target signal does not contain transient chirp in an optical signal output after being input into the laser, and the transmission performance of the optical fiber communication link is improved.
In some embodiments, the preprocessing for removing chirp on the signal to be input according to a preset signal preprocessing strategy may include: when the signal preprocessing strategy is to adjust the power value of the signal to be input, the power value of the signal to be input is adjusted to meet a preset power condition so as to eliminate phase change caused by chirp in an optical signal output by the laser.
Illustratively, the signal to be input includes a first level signal and a second level signal; the first level signal is at 1 level, and the second level signal is at 0 level. In the embodiment of the invention, the phase change of the optical signal caused by the chirp can be eliminated by adjusting the first power value corresponding to the first level signal and the second power value corresponding to the second level signal to meet the preset power condition.
Referring to fig. 10, fig. 10 is a schematic flowchart of a sub-step of adjusting a power value of a signal to be input according to an embodiment of the present invention, which may specifically include the following step S301 and step S302.
Step S301, collecting a first power value of the first level signal and a second power value of the second level signal.
It should be noted that, in the embodiment of the present invention, the first power value of the first level signal and the second power value of the second level signal may be collected by the spectrometer.
For example, a first power value of a first level signal and a second power value of a second level signal may be collected before a signal to be input passes through a low-pass filter; or after the signal to be input passes through the low-pass filter, a first power value of the first level signal and a second power value of the second level signal are collected.
Illustratively, the first power value may be denoted as p 1 (t); the second power value may be denoted as p 2 (t) of (d). It is understood that the first power value and the second power value vary with time t.
Step S302, increasing the first power value and the second power value to make both the first power value and the second power value greater than a preset first power threshold.
It should be noted that the expression of the phase change caused by chirp is:
exp(ja×(ln(p(t))'+k×p(t)))
wherein a represents a transient chirp coefficient; k represents a steady-state chirp coefficient; p (t) denotes a first power value p 1 (t) or second power value p 2 (t); ln (p (t)' represents a phase change caused by transient chirp; a × k × p (t) represents a phase change caused by the steady-state chirp.
It can be understood that, according to the nature of the natural logarithm function ln (x), when x > 1, the slope of ln (x) has a small change, and then (ln (x))' ≈ 0. Therefore, if the power p (t) is amplified to x > 1, the phase change caused by the transient chirp can be eliminated.
For example, the first power value p may be increased by a power amplifier or a circuit amplifier 1 (t) and a second power value p 2 (t) making the first power value p 1 (t) andsecond power value p 2 (t) are both greater than a preset first power threshold. At this time, (ln (p) 1 (t)))' -0 and (ln (p) 2 (t)))′≈0。
The preset first power threshold may be a value far greater than 1, and the specific value is not limited herein. Illustratively, the first power threshold may be 100, 1000, and so on.
By increasing the first power value and the second power value, the first power value and the second power value are both larger than a preset first power threshold, so that phase change caused by transient chirp can be eliminated, and the transmission performance of the optical fiber communication link is improved.
Referring to fig. 11, fig. 11 is a schematic flow chart illustrating another sub-step of adjusting a power value of a signal to be input according to an embodiment of the present invention. After step S301, the following steps S303 and S304 may also be included.
Step S303, a first product between the transient chirp coefficient and the steady-state chirp coefficient is determined.
In some embodiments, determining a first product between the transient chirp coefficient and the steady-state chirp coefficient may include: acquiring a first frequency offset value of a first level signal and a second frequency offset value of a second level signal; and determining a first product between the transient chirp coefficient and the steady-state chirp coefficient according to the first power value and the first frequency offset value or the second power value and the second frequency offset value.
The frequency offset is a shift of a fixed frequency modulation wave frequency to both sides, and may be represented as f.
For example, the first frequency offset value of the first level signal and the second frequency offset value of the second level signal may be determined based on a spectrogram measured from the signal to be input.
Referring to fig. 12, fig. 12 is a spectrum diagram of a signal to be input according to an embodiment of the present invention. As shown in fig. 12, the abscissa 10GHz corresponding to the highest peak is the first frequency offset value of the first level signal; and the abscissa 1.5GHz corresponding to the secondary peak is a second frequency offset value of the second level signal. Of course, the first frequency offset value and the second frequency offset value may be determined according to the actual waveform of the spectrogram, and the specific values are not limited herein.
Illustratively, the relationship between the frequency offset value and the power is as follows:
ak is 2f × p (t) from the above formula.
Illustratively, the first power value p may be based on 1 (t) and a first frequency offset value f 1 Determining a first product ak of the transient chirp coefficient and the steady-state chirp coefficient to be 2f 1 ×p 1 (t)。
Illustratively, the second power value p can also be used 2 (t) and a second frequency offset value f 2 Determining a first product ak of the transient chirp coefficient and the steady-state chirp coefficient to be 2f 2 ×p 2 (t)。
By obtaining a first frequency offset value of the first level signal and a second frequency offset value of the second level signal, a first product between the transient chirp coefficient and the steady-state chirp coefficient can be determined according to a relationship between the frequency offset value and the power.
Step S304, according to a preset modulation coefficient, adjusting the first power value and the second power value, so that a second product between the adjusted first power value and the first product is equal to a preset second power threshold, and a third product between the adjusted second power value and the first product is equal to the second power threshold.
It is understood that, from the expression exp (jax (ln (p (t))' + kxp (t))) of the phase change due to chirp, if a × kxp (t)) > 2 pi m, that is, exp (j2 pi m) > 0, the phase change due to steady-state chirp can be canceled.
Wherein m is a positive integer. Illustratively, the preset second power threshold is 2 pi m, where the positive integer m may be set according to practical situations, and the specific value is not limited herein.
It should be noted that the modulation factor refers to the ratio of the amplitude of the modulation signal to the amplitude of the carrier signal. In the embodiment of the present invention, the modulation factor may be set according to actual conditions, and the specific value is not limited herein.
Illustratively, the modulation factor may be denoted as M; modulation factor M and first power value p 1 (t) second power value p 2 The relationship between (t) is:
for example, the modulation factor M may be 0.85, or may be other values, which is not limited herein. By the above formula, the first power value p is adjusted 1 (t) and a second power value p 2 (t) such that the adjusted first power value p 1 A second product between (t) and the first product ak satisfies a x k p 1 (t) ═ 2 π m; so that the adjusted second power value p 2 A third product between (t) and the first product ak satisfies a x k p 2 (t)＝2πm。
By adjusting the first power value and the second power value according to a preset modulation coefficient, the products of the first power value, the second power value and the first product are all equal to a preset second power threshold value, phase change caused by steady chirp can be eliminated, and the transmission performance of the optical fiber communication link is improved.
Referring to fig. 13, fig. 13 is a schematic flowchart of a sub-step of buffering a signal to be input according to an embodiment of the present invention, which may specifically include the following steps S401 and S402.
Step S401, when the signal preprocessing policy is to perform buffering processing on the signal to be input, determining a rising edge processing time, a falling edge processing time, and a clipping value.
For example, the rising edge processing time may be represented as t 1 (ii) a The falling edge processing time may be represented as t 2 (ii) a The clipping value may be denoted as h. Wherein the rising edge processing time t 1 And a falling edge processing time t 2 And the amplitude limiting value h can be set according to actual conditions, and specific numerical values are not limited herein.
Exemplary, rising edge processing time t 1 May be 7ms, falling edge processing time t 2 May be 8 ms; the clipping value may be 0.05dB, 0.1dB, or 0.15dB, etc.
Step S402, performing advanced rising processing on the rising edge of the signal to be input according to the rising edge processing time and the amplitude limiting value, and performing overshoot processing on the falling edge of the signal to be input according to the falling edge processing time and the amplitude limiting value to obtain the target signal, where the time of the rising edge and the falling edge of the target signal is extended to eliminate phase change caused by chirp in the optical signal output by the laser.
It should be noted that, by performing early rising processing on the rising edge of the signal to be input and performing overshoot processing on the falling edge, phase change caused by chirp in the optical signal can be eliminated, and the transmission performance of the optical fiber communication link is improved.
Referring to fig. 14, fig. 14 is a schematic diagram of a waveform for buffering a signal to be input according to an embodiment of the present invention. As shown in FIG. 14, time t may be processed according to rising edge 1 And the amplitude limiting value h, the rising edge of the signal to be input is subjected to early rising processing; can be processed according to the falling edge 2 And performing overshoot processing on the falling edge of the signal to be input and the amplitude limiting value h to obtain a target signal after buffering processing.
By buffering the signal to be input, the time of the rising edge and the falling edge of the signal to be input is prolonged, and the time of the signal to be input recovering to a stable state after level jump can be shortened, so that the error rate is reduced.
In some embodiments, before inputting the target signal into the laser, the method further comprises: and filtering the target signal through a filter to obtain a filtered target signal.
The target signal here is a target signal obtained by adjusting the power value of the signal to be input before passing through the low-pass filter, or a target signal obtained by buffering the signal to be input.
In some embodiments, inputting the target signal into the laser may include: and inputting the filtered target signal into a laser.
Illustratively, the target signal after being filtered by the low-pass filter is input into a direct modulation laser, and the target signal is converted into an optical signal by the direct modulation laser.
By filtering the target signal according to the low-pass filter, useless high-frequency signals can be filtered out, and the transmission performance of the optical fiber communication link is improved.
In the signal processing method, the network device, and the storage medium provided in the above embodiments, by obtaining the signal to be input of the laser, the preprocessing for removing chirp may be performed on the signal to be input subsequently, so as to avoid that the chirp exists in the optical signal output after the target signal is input into the laser, thereby affecting the quality of the optical signal; the zero and the pole of the transfer function can be obtained by determining the transfer function corresponding to the low-pass filter, so that the position exchange of the zero and the pole of the transfer function can be realized, and the inverse transfer function corresponding to the transfer function is obtained; filtering the signal to be input according to the inverse transformation transfer function, and performing secondary filtering on the filtered signal through the transfer function, so that the obtained target signal is consistent with the signal to be input before filtering and is a square wave signal, and thus the optical signal output after the target signal is input into the laser does not contain transient chirp, and the transmission performance of the optical fiber communication link is improved; the first power value and the second power value are increased to enable the first power value and the second power value to be larger than a preset first power threshold, so that phase change caused by transient chirp can be eliminated, and the transmission performance of an optical fiber communication link is improved; by acquiring a first frequency offset value of the first level signal and a second frequency offset value of the second level signal, a first product between the transient chirp coefficient and the steady-state chirp coefficient can be determined according to the relation between the frequency offset value and the power; the first power value and the second power value are adjusted according to a preset modulation coefficient, so that the products among the first power value, the second power value and the first product are all equal to a preset second power threshold, phase change caused by steady chirp can be eliminated, and the transmission performance of an optical fiber communication link is improved; by carrying out advanced rising processing on the rising edge of the signal to be input and carrying out overshoot processing on the falling edge, phase change caused by chirp in the optical signal can be eliminated, and the transmission performance of an optical fiber communication link is improved; by filtering the target signal according to the low-pass filter, useless high-frequency signals can be filtered out, and the transmission performance of the optical fiber communication link is improved.
The embodiment of the present invention further provides a storage medium, which is used for readable storage, wherein the storage medium stores a program, the program includes program instructions, and the processor executes the program instructions to implement any signal processing method provided in the embodiment of the present invention.
For example, the program is loaded by a processor and may perform the following steps:
acquiring a signal to be input of a laser; and according to a preset signal preprocessing strategy, preprocessing the signal to be input for eliminating chirp to obtain a target signal, and inputting the target signal into the laser.
The storage medium may be an internal storage unit of the network device in the foregoing embodiment, for example, a hard disk or a memory of the network device. The storage medium may also be an external storage device of the network device, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital Card (SD Card), a Flash memory Card (Flash Card), and the like, which are provided on the network device.
It will be understood by those of ordinary skill in the art that all or some of the steps of the methods, systems, and functional modules/units in the devices disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof.
In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on storage media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term storage medium includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as known to those skilled in the art.
The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, and the scope of the invention is not limited thereby. Any modifications, equivalents and improvements which may occur to those skilled in the art without departing from the scope and spirit of the present invention are intended to be within the scope of the claims.
Claims (12)
1. A signal processing method is applied to network equipment, and the method comprises the following steps:
acquiring a signal to be input of a laser;
and according to a preset signal preprocessing strategy, preprocessing the signal to be input for eliminating chirp to obtain a target signal, and inputting the target signal into the laser.
2. The signal processing method of claim 1, wherein the signal pre-processing strategy comprises at least one of:
carrying out filtering offset processing on the signal to be input;
adjusting the power value of the signal to be input;
and buffering the signal to be input.
3. The signal processing method of claim 1, wherein the network device comprises a level signal generator; the method for acquiring the signal to be input of the laser comprises the following steps:
receiving the digital signal generated by the level signal generator;
and performing digital-to-analog conversion on the digital signal to obtain the signal to be input.
4. A signal processing method according to claim 3, wherein a filter is present between the level signal generator and the laser; the preprocessing for eliminating chirp on the signal to be input according to a preset signal preprocessing strategy to obtain a target signal comprises the following steps:
if the signal preprocessing strategy is to perform filtering cancellation processing on the signal to be input, determining a transfer function corresponding to the filter, wherein the transfer function is used for filtering the signal;
exchanging positions of a zero point and a pole of the transfer function to obtain an inverse transfer function corresponding to the transfer function;
filtering the signal to be input according to the inverse transformation transfer function to obtain a filtered signal corresponding to the signal to be input;
and filtering the filtered signal according to the transfer function to obtain the target signal, wherein the target signal is a square wave signal, and an optical signal output by the square wave signal after being input into the laser does not contain chirp.
5. The signal processing method according to claim 3, wherein the preprocessing for removing chirp of the signal to be input according to a preset signal preprocessing strategy comprises:
and when the signal preprocessing strategy is to adjust the power value of the signal to be input, adjusting the power value of the signal to be input to meet a preset power condition so as to eliminate phase change caused by chirp in the optical signal output by the laser.
6. The signal processing method according to claim 5, wherein the signal to be input comprises a first level signal and a second level signal, and the adjusting the power value of the signal to be input meets a preset power condition comprises:
collecting a first power value of the first level signal and a second power value of the second level signal;
and increasing the first power value and the second power value so that the first power value and the second power value are both larger than a preset first power threshold.
7. The signal processing method according to claim 6, wherein after the acquiring the first power value of the first level signal and the second power value of the second level signal, the method further comprises:
determining a first product between a transient chirp coefficient and a steady-state chirp coefficient;
and adjusting the first power value and the second power value according to a preset modulation coefficient, so that a second product between the adjusted first power value and the first product is equal to a preset second power threshold, and a third product between the adjusted second power value and the first product is equal to the second power threshold.
8. The signal processing method of claim 7, wherein determining the first product between the transient chirp coefficient and the steady-state chirp coefficient comprises:
acquiring a first frequency offset value of the first level signal and a second frequency offset value of the second level signal;
determining the first product between the transient chirp coefficient and the steady-state chirp coefficient according to the first power value and the first frequency offset value or the second power value and the second frequency offset value.
9. The signal processing method according to claim 3, wherein the preprocessing for removing chirp on the signal to be input according to a preset signal preprocessing strategy to obtain a target signal comprises:
when the signal preprocessing strategy is to buffer the signal to be input, determining rising edge processing time, falling edge processing time and amplitude limiting value;
and performing advanced rising processing on the rising edge of the signal to be input according to the rising edge processing time and the amplitude limiting value, and performing overshoot processing on the falling edge of the signal to be input according to the falling edge processing time and the amplitude limiting value to obtain the target signal, wherein the time of the rising edge and the time of the falling edge of the target signal are prolonged to eliminate phase change caused by chirp in the optical signal output by the laser.
10. A signal processing method according to any one of claims 5-9, characterized in that a filter is present between the level signal generator and the laser; before the target signal is input into the laser, the method further comprises:
filtering the target signal through the filter to obtain the filtered target signal;
the inputting the target signal into the laser includes:
and inputting the filtered target signal into the laser.
11. A network device, comprising an optical line terminal or an optical network unit, wherein the optical line terminal or the optical network unit comprises a processor and a memory;
the memory is used for storing programs;
the processor for executing the program and implementing the signal processing method according to any one of claims 1 to 10 when executing the program.
12. A storage medium for readable storage, wherein the storage medium stores one or more programs, the one or more programs being executable by one or more processors to implement the signal processing method of any one of claims 1 to 10.
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