CN101729147B - Method and receiver for realizing phase synchronization of coherent light - Google Patents

Abstract

The embodiment of the invention discloses a method and a receiver for realizing phase synchronization of coherent light. The method comprises the following steps that analog/digital conversion of a signal acquired after frequency mixing of a received coherent light signal and a local oscillation signal is carried out and the converted frequency mixing signal comprises the frequency deviation and phase noise of the coherent light signal and the local oscillation signal; the phase error of the frequency mixing signal is extracted by means of logarithm and comprises the frequency deviation and the phase noise; and the phase error is removed from the frequency mixing signal. The method and the receiver extract the phase error acquired after frequency mixing of the received coherent light signal and the local oscillation signal by means of logarithm and then remove the extracted phase error from the frequency mixing signal, thereby realizing the phase synchronization of the received signal and the local oscillation signal, preventing the signal of a coherent communication system from generating phase ambiguity and increasing the accuracy of the phase synchronization and the demodulation efficiency of a receiving system.

Description

Phase locked method of a kind of realization coherent light and receiver

Technical field

The present invention relates to optical communication field, especially relate to phase locked method of a kind of realization coherent light and receiver.

Background technology

Along with growing continuously and fast of network bandwidth requirements in recent years; To the single channel message transmission rate require increasingly high; Therefore, possess the data capacity that promotes existing fiber, support the coherent light reception technique of advantages such as multiple modulation system, receiver sensitivity height to become the research focus of international optical communication field.Coherent light is meant that two bundle direction of vibration are identical, vibration frequency is identical, phase place is identical or phase difference keeps constant light, in the zone that two bundle coherent lights meet, can produce interference.

The coherent light signal that the realization coherent optical communication need receive is identical with the local oscillation signal frequency and the phase place of receiver.But, because generally having necessarily, the light that the laser that uses at present sends (from 100KHz to 100MHz, do not wait) live width, thereby cause receiving certain phase error is arranged between signal and the local oscillation signal.Therefore, adopt certain method to make the phase place and the local oscillation signal that receive signal become one of key technology of coherent optical communication synchronously, by numerous technical staff's broad research.

The method of available technology adopting phase estimation utilizes feed-forward to realize Phase synchronization.This method is specially:

To receive signal and carry out analog/digital conversion (Analog-to-digital conversion, A/D conversion);

Promote biquadratic behind the signal multiplication with signal that is converted to and last cycle;

Ask N length signals sum;

The argument of obtaining this signal is again divided by 4;

The phase error signal that obtains is at last eliminated the phase error in the signal that receives as feedback signal, thereby realize Phase synchronization.

In research and practice process to prior art, inventor of the present invention finds that there is following problem in prior art:

Owing to adopt argument to carry out synchronously, can only detect the phase place of argument scope between [180 ° ,+180 °];, argument just can not solve well-determined phase place when surpassing this scope; Can produce periodically many-valued problem, i.e. phase ambiguity, thus influence the demodulation efficient of receiving system.

Summary of the invention

The technical problem that the embodiment of the invention will solve provides phase locked method of a kind of realization coherent light and receiver, can avoid the coherent communication system signal to produce phase ambiguity, improves the demodulation efficient of Phase synchronization accuracy and receiving system.

For solving the problems of the technologies described above, embodiment provided by the present invention realizes through following technical scheme:

The phase locked method of a kind of realization coherent light:

Signal after coherent light signal that receives and the local oscillation signal mixing is carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal; Utilize logarithm to extract the phase error of said mixed frequency signal, said phase error comprises said frequency shift (FS) and phase noise; From said mixed frequency signal, remove said phase error.

A kind of receiver comprises:

Converting unit is used for the signal after coherent light signal that receives and the local oscillation signal mixing is carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal; Extraction unit is used to utilize logarithm to extract the phase error of the mixed frequency signal after said converting unit is changed, and said phase error comprises said frequency shift (FS) and phase noise; Phasing unit is used for removing said phase error from said mixed frequency signal.

Can find out by technique scheme; The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing; From said mixed frequency signal, remove the phase error of being extracted again; Thereby realize receiving the synchronous of signal and local oscillation signal phase place, can avoid the coherent communication system signal to produce phase ambiguity, improve the demodulation efficient of Phase synchronization accuracy and receiving system.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills; Under the prerequisite of not paying creative work property, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the method flow sketch map of the embodiment of the invention one;

Fig. 2 is the method flow sketch map of the embodiment of the invention two;

Fig. 3 is the method flow sketch map of the embodiment of the invention three;

Fig. 4 is the signal shunt sketch map of the embodiment of the invention three;

Fig. 5 is the parallel processing sketch map of three couples of signal boost M of embodiment of the invention power;

Fig. 6 is the structural representation of embodiment of the invention receiver;

Fig. 7 is another structural representation of embodiment of the invention receiver.

Embodiment

To combine the accompanying drawing in the embodiment of the invention below, the technical scheme in the embodiment of the invention is carried out clear, intactly description, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.

The embodiment of the invention is applicable to quaternary PSK (Quadrature Phase-Shift Keying; QPSK); M system phase-shift keying (M-ary Phase Shift Keying; M-ary PSK), the coherent demodulation system of M ary quadrature amplitude (M-ary Quadrature Amplitude Modulation, M-ary QAM) modulation type.

Embodiment one, specify referring to Fig. 1, Fig. 1 is the method flow sketch map of present embodiment.

Step 101: the signal after coherent light signal that receives and the local oscillation signal mixing is carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal.

The coherent light signal of transmitter emission behind receiver, is sent into 90 degree optical mixer units through Optical Fiber Transmission earlier usually, and local oscillation signal then is transfused to 90 degree optical mixer unit another port usually, and all the other two ports of frequency mixer can be set to 0, are about to its ground connection.After the mixing; Usually coherent light signal that receives and local oscillation signal are imported balanced reciver respectively; Output signal with balanced reciver passes through filter respectively then; And carrying out analog/digital conversion, the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal.

Convert coherent light signal and local oscillation signal into figure pattern, be beneficial to follow-up computing.

Step 102: utilize logarithm to extract the phase error of said mixed frequency signal, said phase error comprises said frequency shift (FS) and phase noise.

Phase error refers to the error that exists between coherent light signal and the local oscillation signal can comprise frequency shift (FS) and phase noise etc.

Mixed frequency signal to through analog/digital conversion utilizes logarithm to extract the phase error between coherent light signal and the local oscillation signal, and logarithm can adopt natural logrithm, obviously, adopts other logarithms also not influence the realization of the embodiment of the invention.

The phase error that can extract coherent light signal according to natural logrithm is c _k=1n A+j (4 Δ wkT _s+ 4 Δ φ _k), wherein, Δ w is the frequency shift (FS) of said coherent light signal and said local oscillation signal, and Δ φ is the phase noise of said coherent light signal and said local oscillation signal, and k represents k sampling period, and Ts refers to the sampling period, j is the unit of imaginary part in the plural number, A=s _k ⁴, be a real number, S _kRepresentative is in the information bit of k sampling instant, and information bit refers to that phase information institute is on the throne.

Utilize logarithm to extract phase error, then strengthened the large frequency-difference disposal ability, thereby avoided exceeding the argument scope in the prior art and the phase ambiguity that produces.

Step 103: from said mixed frequency signal, remove said phase error.

Removing said phase error can adopt multiplier to realize; With the phase error of extracting and the mixed frequency signal elimination phase error that multiplies each other; Promptly realized certainly, adopting other modes from said mixed frequency signal, to remove the realization that said phase error does not influence the embodiment of the invention yet synchronously.

Signal has synchronously been eliminated phase error, sends into follow-up equalizing circuit and data recovery circuit, carries out processing such as EDC (Electrical dispersion compensation), data recovery.

The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing; From said mixed frequency signal, remove the phase error of being extracted again; Realize receiving the synchronous of signal and local oscillation signal phase place; Can avoid the coherent communication system signal to produce phase ambiguity, improve the demodulation efficient of Phase synchronization accuracy and receiving system.

In the practical application, can carry out parallel processing to coherent light signal and local oscillation signal, second following examples specify the practical application flow process.

Embodiment two, specify referring to Fig. 2, Fig. 2 is the method flow sketch map of present embodiment.

Step 201: the signal after coherent light signal that receives and the local oscillation signal mixing is carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal.

After the mixing; Usually coherent light signal that receives and local oscillation signal are imported balanced reciver respectively; Output signal with balanced reciver passes through filter respectively then; And carrying out analog/digital conversion, the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal.

Step 202: said mixed frequency signal is divided into two-way, one road input time delay device, the one tunnel utilizes logarithm to extract the phase error between the coherent light signal and local oscillation signal in the said mixed frequency signal.

Can mixed frequency signal be divided into two-way by power averaging through signal shunt, every road all comprises the complete information of coherent light signal and local oscillation signal; So that after in road mixed frequency signal from the two-way shunt, extracting said phase error, from the mixed frequency signal of another road time-delay, remove said phase error.

Mixed frequency signal to through analog/digital conversion utilizes logarithm to extract the phase error of coherent light signal, and said logarithm can adopt natural logrithm, obviously, adopts other logarithms also not influence the realization of the embodiment of the invention.

Step 203: the phase error that is extracted is removed from the mixed frequency signal after the time-delay.

Removing said phase error can adopt multiplier to realize; Mixed frequency signal after the phase error of just extracting and the time-delay elimination phase error that multiplies each other; Realize certainly, adopting other modes to realize from mixed frequency signal, removing the realization that said phase error does not influence the embodiment of the invention yet synchronously.

The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing; From said mixed frequency signal, remove the phase error of being extracted again; Realize receiving the synchronous of signal and local oscillation signal phase place; Can avoid the coherent communication system signal to produce phase ambiguity, improve the Phase synchronization accuracy; And mixed frequency signal is divided into two-way, adopts parallel processing to carry out feed-forward and eliminate phase error, improve Synchronous Processing speed.

In the practical application, also need coherent light information is removed the processing of interference, three of following examples specify the practical application flow process.

Embodiment three, specify referring to Fig. 3, Fig. 3 is the method flow sketch map of present embodiment.

Step 301: the signal after coherent light signal that receives and the local oscillation signal mixing is carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal.

After the mixing; Usually coherent light signal that receives and local oscillation signal are imported balanced reciver respectively; Output signal with balanced reciver passes through filter respectively then; And carrying out analog/digital conversion, the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal.If the coherent light signal that receives does

Local oscillation signal does

Wherein, m (t) is a noise signal, ω _sBe the frequency of coherent light signal, It is the first phase of coherent light signal; ω _LBe the frequency of local oscillation signal,

Be the first phase of local oscillation signal, Ts refers to the sampling period, and k represents k sampling period, and j is the unit of imaginary part in the plural number.

Can 90 ° of desirable devices that Optical Hybrid is photomixing (ripple) device, wherein the coupler transfer function is: $\left(\begin{array}{cc}\frac{1}{\sqrt{2}}& j\frac{1}{\sqrt{2}}\\ j\frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}\end{array}\right),$ If the input signal of 90 ° of Optical Hybrid is respectively E ₁₁, E ₁₂, E ₂₁, E ₂₂, be output as E ₃₃, E ₃₄, E ₄₃, E ₄₄, E wherein ₁₂, E ₂₁Be zero, and

Then have:

$\left(\begin{array}{c}{\stackrel{\→}{E}}_{33}\\ {\stackrel{\→}{E}}_{34}\end{array}\right)=\left(\begin{array}{c}\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11}\\ j\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11}\end{array}\right)$

$\left(\begin{array}{c}{\stackrel{\→}{E}}_{43}\\ {\stackrel{\→}{E}}_{44}\end{array}\right)=\left(\begin{array}{c}j\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11}\\ -\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11}\end{array}\right)$

Thereby can draw coherent light signal I, local oscillation signal Q is respectively

$I={\left|{\stackrel{\→}{E}}_{34}\right|}^2-{\left|{\stackrel{\→}{E}}_{33}\right|}^2={|j\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11}|}^2-{|\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11}|}^2$

$=(j\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11})(j\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11})*-(\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11})(\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11})*$

$=(j\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11})(-j\frac{1}{2}{\stackrel{\→}{E}}_{22}*-j\frac{1}{2}{\stackrel{\→}{E}}_{11}*)-(\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11})(\frac{1}{2}{\stackrel{\→}{E}}_{22}*-\frac{1}{2}{\stackrel{\→}{E}}_{11}*)$

$=\frac{1}{4}({\left|{\stackrel{\→}{E}}_{22}\right|}^2+{\stackrel{\→}{E}}_{22}{\stackrel{\→}{E}}_{11}*+{\stackrel{\→}{E}}_{11}{\stackrel{\→}{E}}_{22}*+{\left|{\stackrel{\→}{E}}_{11}\right|}^2)$

$-\frac{1}{4}({\left|{\stackrel{\→}{E}}_{22}\right|}^2-{\stackrel{\→}{E}}_{22}{\stackrel{\→}{E}}_{11}*-{\stackrel{\→}{E}}_{11}{\stackrel{\→}{E}}_{22}*+{\left|{\stackrel{\→}{E}}_{11}\right|}^2)$

$=\frac{1}{2}({\stackrel{\→}{E}}_{22}{\stackrel{\→}{E}}_{11}*+{\stackrel{\→}{E}}_{11}{\stackrel{\→}{E}}_{22}*)$

$=\mathrm{Re}({\stackrel{\→}{E}}_{22}{\stackrel{\→}{E}}_{11}*)$

$Q={\left|{\stackrel{\→}{E}}_{43}\right|}^2-{\left|{\stackrel{\→}{E}}_{44}\right|}^2={|j\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11}|}^2-{|-\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11}|}^2$

$=(j\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11})(j\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11})*-(-\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11})(-\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11})*$

$=(j\frac{1}{2}{\stackrel{\→}{E}}_{22}-\frac{1}{2}{\stackrel{\→}{E}}_{11})(-j\frac{1}{2}{\stackrel{\→}{E}}_{22}*-\frac{1}{2}{\stackrel{\→}{E}}_{11}*)-(-\frac{1}{2}{\stackrel{\→}{E}}_{22}+j\frac{1}{2}{\stackrel{\→}{E}}_{11})(-\frac{1}{2}{\stackrel{\→}{E}}_{22}*-j\frac{1}{2}{\stackrel{\→}{E}}_{11}*)$

$=\frac{1}{4}({\left|{\stackrel{\→}{E}}_{22}\right|}^2-j{\stackrel{\→}{E}}_{22}{\stackrel{\→}{E}}_{11}*+j{\stackrel{\→}{E}}_{11}{\stackrel{\→}{E}}_{22}*+{\left|{\stackrel{\→}{E}}_{11}\right|}^2)$

$-\frac{1}{4}({\left|{\stackrel{\→}{E}}_{22}\right|}^2+j{\stackrel{\→}{E}}_{22}{\stackrel{\→}{E}}_{11}*-j{\stackrel{\→}{E}}_{11}{\stackrel{\→}{E}}_{22}*+{\left|{\stackrel{\→}{E}}_{11}\right|}^2)$

$=\frac{1}{2}(-j{\stackrel{\→}{E}}_{22}{\stackrel{\→}{E}}_{11}*+j{\stackrel{\→}{E}}_{11}{\stackrel{\→}{E}}_{22}*)$

$=\mathrm{Im}({\stackrel{\→}{E}}_{22}{\stackrel{\→}{E}}_{11}*)$

Thereby can obtain:

Wherein, Δ ω=ω _S-ω _L, represent the frequency shift (FS) of said coherent light signal and said local oscillation signal,

Represent the phase noise of said coherent light signal and said local oscillation signal, m (t) representes noise signal, and j is the unit of imaginary part in the plural number.

After the A/D variation, it is the same that following formula can be changed into

each parameter meaning.

Step 302: said mixed frequency signal is divided into A, B two-way, A road input time delay device, the B road utilizes logarithm to extract the phase error of said mixed frequency signal.

Can signal be divided into A, B two-way by power averaging through signal shunt, every road all comprises the complete information of coherent light signal and local oscillation signal.Referring to Fig. 4, Fig. 4 is the signal shunt sketch map of present embodiment.

Coherent light signal and local oscillation signal to through analog/digital conversion utilize logarithm to extract the phase error of coherent light signal, and logarithm can adopt natural logrithm, obviously, adopt other logarithms also not influence the realization of the embodiment of the invention.

If a _k=I _k+ jQ _k, be output as after the signal shunt shunt

Step 303: the processing of B road signal being removed interference.

The processing of remove disturbing can comprise the influence of removing information bit and remove noise effect etc., specifically processing can for: at first it is asked the M power, then averaged; Perhaps can for: will promote said signal behind the M power divided by M.

The value of M when using the different modulating form is different, and M gets 4 when using the QPSK modulation format, and M gets 4 integral multiple when using M-ary PSK modulation format.With the QPSK modulation format is example, can obtain:

b _k＝<(a _k) ⁴>

＝<[s _kexp(jΔwkT _s+jΔφ _k)+m(kT _s)] ⁴>

＝<s _k ⁴exp(j4ΔwkT _s+j4Δφ _k)>

+<4s _k ³exp(j3ΔwkT _s+j3Δφ _k)m(kT _s)>

+<6s _k ²exp(j2ΔwkT _s+j2Δφ _k)m ²(kT _s)>

+<4s _kexp(jΔwkT _s+jΔφ _k)m ³(kT _s)>

+<m ⁴(kT _s)>

Because m _k(kT _s) be white Gaussian noise, so can ignore for its high-order term.Thereby obtain:

b _k＝<s _k ⁴exp(j4ΔwkT _s+j4Δφ _k)>

+<4s _k ³exp(j3ΔwkT _s+j3Δφ _k)m(kT _s)>

In addition, can learn that second mean value in the following formula is zero, thereby can obtain: b according to the statistical property of signal _k=<s _k ⁴Exp (j4 Δ w _kTs+j4 Δ φ _k)>, wherein, A=s _k ⁴, be a real number, S _kRepresentative is in the information bit of k sampling instant, and information bit refers to that phase information institute is on the throne, and other each parameter meanings are the same.

Ask the M power can take binding signal splitter and multiplier to wait to B road signal and realize,, multiply each other then as earlier along separate routes with signal; Along separate routes, multiply each other again again, can realize the quadruplicate purpose of signal boost; Can adopt parallel processing technique, to improve the reaction speed and the disposal ability of system.Concrete grammar can be as shown in Figure 5, and Fig. 5 is the parallel processing sketch map to signal boost M power.

Step 304: utilize logarithm to extract phase error to B road signal.

Logarithm is an example with the natural logrithm, then has: c _k=1n A+j (4 Δ wkT _s+ 4 Δ φ _k), wherein each parameter meaning is ditto said.

This step can be through FPGA look-up table (Look-up Table LUT) realizes.Because of designing the look-up table of much scales; And select processing speed and the phase locked precision that step-length can influence system of searching how long for use, and for example the scale of look-up table is big more, and it is more little to search step-length; Phase locked precision is just high more, but the processing speed of system can descend.Therefore, the scale of look-up table with search step-length and can compromise according to actual conditions and choose, but do not influence the realization of the embodiment of the invention.

Relatively low or system requires in the relatively low system Phase synchronization in system's speed; Like the 10G system; Perhaps channel condition is preferably in the 40G system (system all smaller like newly-built various damages); Also can sue for peace, and then it is averaged, to improve accuracy the output of N phase error.

Step 305: the imaginary part of extracting phase error.

Extract imaginary part and obtain d _k=Im (ck ₎/ 4=Δ wkT _s+ Δ φ _k

Step 306: it is on the index of exponential function at the end that phase error is adjusted to e.

The phase error f that extracts _k=exp ^-1(j Δ wkT _s+ j Δ φ _k).

Step 307: the phase error that is extracted is removed from the A road signal after the time-delay, realize the synchronous of coherent light signal and local oscillation signal.

After removing the phase error in the coherent light signal, then coherent light signal and local oscillation signal have been carried out synchronously.

Removing said phase error can adopt multiplier to realize; With the phase error of extracting and the mixed frequency signal elimination phase error that multiplies each other; Realize certainly, adopting other modes to realize from mixed frequency signal, removing the realization that said phase error does not influence the embodiment of the invention yet synchronously.

The delay time of A road delayer should equal the summation of signal processing time in step 303 to the step 306, and its input signal is

output signal for r for the time-delay sampling period.

In the embodiment of the invention, when adopting multiplier, input signal is respectively A road signal

F with B road signal _k=exp ^-1(j Δ wkT _s+ j Δ φ _k), be output as g _k=s _k(nT _s), each parameter meaning is with aforementioned.

The road signal that extracts phase error is carried out processed steps 303 to step 306 can pass through DSP (Digital Signal Processor; Digital signal processor) or FPGA (Field-ProgrammableGate Array; Programmable gate array) realize, thus can integrated difficulty and the system's implementation complexity of mitigation system.

And, before and after the enforcement of step 303 to step 306, all can use filter to carry out filtering, the influence of the noise component(s) in the erasure signal as much as possible, thereby the signal to noise ratio of raising system.Can adopt some present main flow filters to realize filter function.Certainly, under the bigger situation of channel signal to noise ratio, filter can omit according to actual conditions.

The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing; From said mixed frequency signal, remove the phase error of being extracted again; Realize receiving the synchronous of signal and local oscillation signal phase place; Can avoid the coherent communication system signal to produce phase ambiguity, improve the Phase synchronization accuracy; And mixed frequency signal is divided into two-way, adopts parallel processing to carry out feed-forward and eliminate phase error, improve Synchronous Processing speed; And mixed frequency signal removed the processing of interference, further improve the demodulation efficient of phase locked accuracy and receiving system.

Need to prove; For aforesaid each method embodiment, for simple description, so it all is expressed as a series of combination of actions; But those skilled in the art should know; The present invention does not receive the restriction of described sequence of movement, because according to the present invention, some step can adopt other orders or carry out simultaneously.Secondly, those skilled in the art also should know, the embodiment described in the specification all belongs to preferred embodiment, and related action and module might not be that the present invention is necessary.

In the above-described embodiments, the description of each embodiment is all emphasized particularly on different fields, do not have the part that details among certain embodiment, can be referring to the associated description of other embodiment.

More than provide a kind of realization coherent light phase locked method, the embodiment of the invention also provides a kind of receiver.

A kind of receiver 500, referring to Fig. 6, Fig. 6 is the structural representation of embodiment of the invention receiver, comprising:

Converting unit 501 is used for the signal after coherent light signal that receives and the local oscillation signal mixing is carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal; Convert coherent light signal and local oscillation signal into figure pattern, be beneficial to follow-up computing.

Extraction unit 502 is used to utilize logarithm to extract the phase error of the mixing after said converting unit 501 is changed; Phase error refers to the error between coherent light signal and the local oscillation signal, can comprise frequency shift (FS) and phase noise etc., and logarithm can adopt natural logrithm, obviously, adopts other logarithms also not influence the realization of the embodiment of the invention.

Phasing unit 503 is used for removing the said phase error that extraction unit 502 extracts from said mixed frequency signal.

Said receiver can also comprise that referring to Fig. 7, Fig. 7 is another structural representation of embodiment of the invention receiver except above-mentioned converting unit 501, extraction unit 502, phasing unit 503:

Remove interference units 504, be used for before extraction unit 502 utilizes logarithm to extract the phase error of mixed frequency signal, the signal that has carried out analog/digital conversion is removed to disturb handle, can comprise following subelement:

M power unit 505, the mixed frequency signal that is used for converting unit was changed promotes the M power, and said M is 4 integral multiple;

Mean value unit 506 is used for the mixed frequency signal that M power unit 505 promotes the M power is averaged.

Perhaps, remove interference units 504 and can comprise following subelement:

M power unit 505, the mixed frequency signal that is used for converting unit was changed promotes the M power, and said M is 4 integral multiple;

Ask merchant unit 507, the mixed frequency signal that is used for M power unit 505 is promoted the M power is divided by M.

Said influence and the The noise that interference units 504 can be removed information bit, the accuracy of raising receiving system processing signals removed.

Said receiver can also comprise:

Branching unit; Be used for before the mixed frequency signal that has carried out analog/digital conversion being removed the interference processing except that interference units; Mixed frequency signal after the converting unit conversion is divided into two-way, one road input time delay device, the one tunnel utilizes logarithm to extract the phase error of said mixed frequency signal.

Removing phase error can adopt multiplier to realize; With the elimination phase error that multiplies each other of the mixed frequency signal after the phase error of extracting and the time-delay; Realize certainly, adopting other modes to realize from mixed frequency signal, removing the realization that said phase error does not influence the embodiment of the invention yet synchronously.

The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing; From said mixed frequency signal, remove the phase error of being extracted again; Realize receiving the synchronous of signal and local oscillation signal phase place; Can avoid the coherent communication system signal to produce phase ambiguity, improve the Phase synchronization accuracy; And mixed frequency signal is divided into two-way, adopts parallel processing to carry out feed-forward and eliminate phase error, improve Synchronous Processing speed; And mixed frequency signal removed the processing of interference, further improve the demodulation efficient of phase locked accuracy and receiving system.

One of ordinary skill in the art will appreciate that; Realize all or part of flow process in the foregoing description method; Be to instruct relevant hardware to accomplish through computer program; Described program can be stored in the computer read/write memory medium, and this program can comprise the flow process like the embodiment of above-mentioned each side method when carrying out.Wherein, described storage medium can be magnetic disc, CD, read-only storage memory body (Read-OnlyMemory, ROM) or at random store memory body (Random Access Memory, RAM) etc.

More than phase locked method of a kind of realization coherent light and receiver that the embodiment of the invention provided have been carried out detailed introduction; Used concrete example among this paper principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that on embodiment and range of application, all can change, in sum, this description should not be construed as limitation of the present invention.

Claims (13)

1. realize the phase locked method of coherent light for one kind, it is characterized in that:

Signal after coherent light signal that receives and the local oscillation signal mixing is carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal;

Utilize logarithm to extract the phase error of said mixed frequency signal, said phase error comprises said frequency shift (FS) and phase noise;

From said mixed frequency signal, remove said phase error.

2. the phase locked method of realization coherent light according to claim 1 is characterized in that, said phase error through logarithm extraction mixed frequency signal is specially:

Extract the phase error of mixed frequency signal through natural logrithm.

3. the phase locked method of realization coherent light according to claim 2 is characterized in that, said phase error through natural logrithm extraction mixed frequency signal is specially:

Extract the phase error c of mixed frequency signal according to natural logrithm _k=ln A+j (4 Δ wkT _s+ 4 Δ φ _k), wherein, Δ w is the frequency shift (FS) of said coherent light signal and said local oscillation signal, and Δ φ is the phase noise of said coherent light signal and said local oscillation signal, and k represents k sampling period, and Ts refers to the sampling period, j is the unit of imaginary part in the plural number, A=s _k ⁴, be a real number, S _kRepresentative is in the information bit of k sampling instant.

4. the phase locked method of realization coherent light according to claim 1 is characterized in that, also comprises before the said phase error of utilizing logarithm to extract said mixed frequency signal:

The said coherent light signal of the process analog/digital conversion that receives is removed the processing of interference.

5. the phase locked method of realization coherent light according to claim 4 is characterized in that, the said processing that the coherent light signal that receives is removed interference is specially:

Coherent light signal is promoted the M power;

Divided by M, said M is 4 integral multiple with the said signal behind the lifting M power.

6. the phase locked method of realization coherent light according to claim 4 is characterized in that, the said processing that the coherent light signal that receives is removed interference is specially:

Coherent light signal is promoted the M power;

To the said signal averaged behind the lifting M power, said M is 4 integral multiple.

7. according to claim 5 or the phase locked method of 6 described realization coherent lights, it is characterized in that said M value is 4 when using the quaternary PSK modulation format.

8. according to the phase locked method of each described realization coherent light of claim 1 to 6, it is characterized in that, before the said phase error of utilizing logarithm to extract said mixed frequency signal, also comprise:

To pass through comprising of analog/digital conversion said coherent light signal and the signal of local oscillation signal carry out the shunt parallel processing; Correspondingly,

Saidly from said mixed frequency signal, remove said phase error and be specially:

The said phase error that to from one road mixed frequency signal of said shunt, obtain is removed from another road mixed frequency signal.

9. according to the phase locked method of each described realization coherent light of claim 1 to 6, it is characterized in that, said utilize the phase error that logarithm extracts said mixed frequency signal after, also comprise before from said mixed frequency signal, removing said phase error:

Extract the imaginary part of said phase error;

Regulate said imaginary part to being on the index of exponential function at the end with e.

10. a receiver is characterized in that, comprising:

Converting unit is used for the signal after coherent light signal that receives and the local oscillation signal mixing is carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of said coherent light signal and said local oscillation signal;

Extraction unit is used to utilize logarithm to extract the phase error of the mixed frequency signal after said converting unit is changed, and said phase error comprises said frequency shift (FS) and phase noise;

Phasing unit is used for removing said phase error from said mixed frequency signal.

11. receiver according to claim 10 is characterized in that, also comprises:

Remove interference units, be used for before said extraction unit utilizes logarithm to extract the phase error of mixed frequency signal, the signal that has carried out analog/digital conversion is removed to disturb handle.

12. receiver according to claim 11 is characterized in that, the said interference units of removing specifically comprises:

M power unit, the mixed frequency signal that is used for said converting unit was changed promotes the M power, and said M is 4 integral multiple;

The mean value unit is used for the mixed frequency signal of said M power unit lifting M power is averaged.

13. receiver according to claim 11 is characterized in that, the said interference units of removing specifically comprises:

M power unit, the mixed frequency signal that is used for said converting unit was changed promotes the M power, and said M is 4 integral multiple;

Ask the merchant unit, the mixed frequency signal that is used for said M power unit is promoted the M power is divided by M.

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