CN102340468A - Method and device used for controlling amplitude of driving signals and DQPSK transmitter system - Google Patents

Abstract

The invention discloses a method and device used for controlling the amplitude of driving signals in a DQPSK (Differential Quadrature Phase Shift Keying) transmitter system and a DQPSK transmitter system. The method used for controlling the amplitude of driving signals comprises the step of: controlling the amplitudes of a quadrature Q channel driving signal and an in-phase I channel driving signal which are input into a DQPSK modulator and stabilizing at 2VPi by maximizing the average output power of the DQPSK modulator in the DQPSK transmitter system, wherein VPi is half wave voltage of the DQPSK modulator. According to the method and device and the DQPSK transmitter system disclosed by the invention, high-quality modulation of DQPSK optical signals is realized, and the performance of the entire DQPSK transmitter system is improved.

Description

The control method of drive signal amplitude and device, DQPSK transmitter system

Technical field

The present invention relates to the communications field, the control method of drive signal amplitude and device, DQPSK transmitter system in a kind of DQPSK transmitter system.

Background technology

In recent years, along with the raising of optical transmission system speed and the increase of capacity, in the optical fiber transmission technique field of optical fiber transmission technique field, particularly dense wave division multipurpose (DWDM), with DQPSK the attention that the light phase modulation method of representative more and more receives industry.DQPSK (Differential Quadrature Phase Shift Keying; Difference quadrature phase shift keying) modulator approach is to come transmission information with four out of phase differences of code element before and after the light signal; Therefore its code element speed has only the half the of traditional light amplitude modulation method; Thereby have superior chromatic dispersion and polarization mode dispersion performance and higher band efficiency, be applicable to the optical transmission system of big capacity, long distance more.

In DQPSK transmitter system as shown in Figure 1; Comprise DQPSK modulator and driver I, Q; Two-way drive signal through driver I and driver Q input DQPSK modulator (comprises Q road drive signal and I road drive signal respectively; Wherein, Q representes that quadrature, I represent homophase) amplitude equate to make four phase places of the DQPSK signal that modulation obtains to divide equally on 0,2 π, the PHASE SEPARATION degree is maximum and identical.Simultaneously, the amplitude when the two-way drive signal all equals 2 times of V _π(V _πHalf-wave voltage for the DQPSK modulator) time, the highest and DQPSK modulation signal that obtains of the modulation efficiency of DQPSK modulator best in quality.

But, the amplitude of the two-way drive signal of input DQPSK modulator is not controlled in the correlation technique at present, thereby is made that the modulation efficiency of DQPSK modulator is relatively poor, and then influenced the performance of whole DQPSK transmitter system.

Summary of the invention

Main purpose of the present invention is to provide control method and device, the DQPSK transmitter system of drive signal amplitude in a kind of DQPSK transmitter system; Make that to solve the above-mentioned amplitude of the two-way drive signal of input DQPSK modulator control at least the modulation efficiency of DQPSK modulator is relatively poor, influence the problem of the performance of whole DQPSK transmitter system.

According to an aspect of the present invention; The control method of drive signal amplitude in a kind of differential quadrature phased shift keying DQPSK transmitter system is provided; Comprise: through the average output power of the DQPSK modulator in the maximization DQPSK transmitter system, the quadrature Q road drive signal of control input DQPSK modulator and the amplitude of homophase I road drive signal all are stabilized in 2V _π, wherein, V _πHalf-wave voltage for the DQPSK modulator.

According to a further aspect in the invention; The control device of drive signal amplitude in a kind of differential quadrature phased shift keying DQPSK transmitter system is provided; Comprise: first adjustment module; The current amplitude of first via drive signal of quadrature Q road drive signal and homophase I road drive signal that is used for keeping importing the DQPSK modulator is constant; Regulate the average output power maximum of the current amplitude of the second tunnel drive signal in Q road drive signal and the I road drive signal up to the DQPSK modulator, and the amplitude of the current amplitude of the second tunnel drive signal after being set to regulate; Second adjustment module is used to keep the amplitude of the second tunnel drive signal constant for the amplitude after regulating, and the amplitude of regulating first via drive signal is maximum up to average output power, and the amplitude of the current amplitude of first via drive signal after being set to regulate; Operational module is used to control the operation that first adjustment module and second adjustment module repeat separately successively and makes the amplitude of Q road drive signal and I road drive signal all reach 2V _π, wherein, V _πHalf-wave voltage for the DQPSK modulator.

According to another aspect of the invention; A kind of differential quadrature phased shift keying DQPSK transmitter system is provided; Comprise: DQPSK modulator, driver I, driver Q and control device, wherein, driver I; Be used under the control of first control signal that control device is exported, the I road drive signal of output DQPSK modulator is to the DQPSK modulator; Driver Q is used under the control of second control signal that control device is exported, and the Q road drive signal of output DQPSK modulator is to the DQPSK modulator; Control device is used for repeating to adjust according to following rule the amplitude of one tunnel drive signal of quadrature Q road drive signal and the homophase I road drive signal of input DQPSK modulator, makes the amplitude of Q road drive signal and I road drive signal all reach 2V _π: the Q road drive signal of maintenance input DQPSK modulator and the current amplitude of the first via drive signal in the drive signal of I road are constant; Regulate the average output power maximum of the current amplitude of the second tunnel drive signal in Q road drive signal and the I road drive signal up to the DQPSK modulator, and the amplitude of the current amplitude of the second tunnel drive signal after being set to regulate; The amplitude that keeps the second tunnel drive signal is constant for the amplitude after regulating, and the amplitude of regulating first via drive signal is maximum up to average output power, and the amplitude of the current amplitude of first via drive signal after being set to regulate; Wherein, V _πHalf-wave voltage for the DQPSK modulator.

Through the present invention; Amplitude through keeping one of Q road drive signal and I road drive signal successively is constant; The amplitude of regulating another road is with the maximization average optical output power, repeat repeatedly after, can make the amplitude of two-way drive signal of input DQPSK modulator equate and be equal to 2V _π, promptly all be stabilized in 2 times of V _πThereby solved in the correlation technique and do not made that owing to the amplitude of two-way drive signal being controlled the modulation efficiency of DQPSK modulator is relatively poor; Influenced the problem of the performance of whole DQPSK transmitter system; And then realized the modulation of high-quality DQPSK light signal, and improved the performance of whole DQPSK transmitter system.

Description of drawings

Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute improper qualification of the present invention.In the accompanying drawings:

Fig. 1 is the structural representation according to the DQPSK emission system of correlation technique;

Fig. 2 is the flow chart according to the control method of drive signal amplitude in the DQPSK transmitter system of the embodiment of the invention;

Fig. 3 is the flow chart of the control method of drive signal amplitude in the DQPSK transmitter system according to the preferred embodiment of the invention;

Fig. 4 is the sketch map of the control device of drive signal amplitude in the DQPSK transmitter system of implementing according to the present invention;

Fig. 5 is the structural representation of the DQPSK transmitter system of enforcement according to the present invention;

Fig. 6 is the structural representation of the DQPSK transmitter system preferably implemented according to the present invention.

Embodiment

Hereinafter will and combine embodiment to specify the present invention with reference to accompanying drawing.Need to prove that under the situation of not conflicting, embodiment and the characteristic among the embodiment among the application can make up each other.

Fig. 2 is according to the flow chart of the control method of the drive signal amplitude that is applied to the DQPSK modulator in the DQPSK transmitter system as shown in Figure 1 of the embodiment of the invention, may further comprise the steps:

Step S202, through the average output power of the DQPSK modulator in the maximization DQPSK transmitter system, the Q road drive signal of this DQPSK modulator of control input and the amplitude of I road drive signal all are stabilized in 2V _π, wherein, V _πHalf-wave voltage for the DQPSK modulator.

Particularly, as shown in Figure 3, step S202 may further comprise the steps:

Step S302; The Q road drive signal of maintenance input DQPSK modulator and the current amplitude of the first via drive signal in the drive signal of I road are constant; Regulate the average output power maximum of the current amplitude of the second tunnel drive signal in Q road drive signal and the I road drive signal up to the DQPSK modulator, and the amplitude of the current amplitude of the second tunnel drive signal after being set to regulate;

Step S304, the amplitude that keeps the second tunnel drive signal is constant for the amplitude after regulating, and the amplitude of regulating first via drive signal is maximum up to average output power, and the amplitude of the current amplitude of first via drive signal after being set to regulate;

Repeating step S302 and step S304 make the amplitude of Q road drive signal and I road drive signal all reach 2V successively _π, wherein, V _πHalf-wave voltage for the DQPSK modulator.

Here be the cyclic process of a step S302 and step S304; After step S304; The amplitude that keeps first via drive signal once more is that the amplitude after regulating among the step S304 is constant, and the amplitude of regulating above-mentioned the second tunnel drive signal makes average output power maximum; Carry out successively, the amplitude that promptly at every turn all remains after regulated last time is constant, the amplitude of regulating another road.

In the correlation technique owing to the amplitude of the two-way drive signal of input DQPSK modulator is not controlled, thereby make that the modulation efficiency of DQPSK modulator is relatively poor, and then influenced the performance of whole DQPSK transmitter system.Present embodiment is constant through the amplitude that keeps one of Q road drive signal and I road drive signal successively; The amplitude of regulating another road is with the maximization average optical output power; After repeating repeatedly, can make the amplitude of two-way drive signal of input DQPSK modulator equate and be equal to 2V _π, promptly all be stabilized in 2 times of V _πThereby solved in the correlation technique and do not made that owing to the amplitude of two-way drive signal being controlled the modulation efficiency of DQPSK modulator is relatively poor; Influenced the problem of the performance of whole DQPSK transmitter system; And then realized the modulation of high-quality DQPSK light signal, and improved the performance of whole DQPSK transmitter system.The method that the present invention implements to be adopted has adopted cyclic process, and method is simple, not only helps Digital Implementation, and has the low and high reliability features of cost.

Preferably, before step S302, also comprise: step S300, the current amplitude of initialization Q road drive signal and I road drive signal.

Preferably, in above-mentioned method, above-mentioned first via drive signal is a Q road drive signal, and the second tunnel drive signal is an I road drive signal; Perhaps, first via drive signal is an I road drive signal, and the second tunnel drive signal is a Q road drive signal.Because Q road drive signal and I road drive signal are symmetric relations, therefore in the process of practical implementation, regulate the arbitrary Lu Junke in this two-way drive signal earlier, thereby can implement concrete control procedure neatly.

When first via drive signal is a Q road drive signal; When the second tunnel drive signal is I road drive signal; Above-mentioned control method is specific as follows: step 1.; The fixing current amplitude of Q road drive signal, the current amplitude of regulating I road drive signal makes the output average light power maximum, and the amplitude (step S302 in this step corresponding above-mentioned Fig. 3) of the current amplitude of I road drive signal after being set to regulate; Step 2.; The fixing current amplitude of I road drive signal; The current amplitude of regulating Q road drive signal makes the output average light power maximum, and the amplitude (step S304 in this step corresponding above-mentioned Fig. 3) of the current amplitude of Q road drive signal after being set to regulate.Repeat successively above-mentioned steps 1. with step 2., can realize that after repeating repeatedly the amplitude of two-way drive signal all equals 2 times of V _π

Obviously, because the symmetry on Q road and I road, 1. also can regulate the amplitude of I road drive signal earlier in the step of above-mentioned method, and then step 2. in the amplitude of adjusting Q road drive signal.The concrete steps here are the same, repeat no more.

Preferably, keep the amplitude of Q road drive signal constant, the amplitude of regulating I road drive signal comprises up to the average output power maximum of DQPSK modulator: the amplitude of the I road drive signal through following formula (3) after adjusted:

${\cos \mathrm{\φ}}_{\mathrm{mI}}=\frac{\cos {2\mathrm{\φ}}_{\mathrm{IQ}}{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bI}}-1}{\cos \mathrm{\φ}}_{\mathrm{mQ}}---\left(3\right)$

Wherein,

2V _{D, I}The amplitude of expression I road drive signal, 2V _{D, Q}The amplitude of expression Q road drive signal, 2 φ _IQPhase delay cell bias point in the expression DQPSK modulator, φ _BIThe bias point on expression I road, φ _BQThe bias point on expression Q road.

It is constant in the amplitude that keeps Q road drive signal that the preferred embodiment provides, when making the average output power of DQPSK modulator get maximum, and the condition that amplitude satisfied of I road drive signal.

Preferably, keep the amplitude of I road drive signal constant, the amplitude of regulating Q road drive signal comprises up to the average output power maximum of DQPSK modulator: the amplitude of the Q road drive signal through following formula (4) after adjusted:

${\cos \mathrm{\φ}}_{\mathrm{mQ}}=\frac{\cos {2\mathrm{\φ}}_{\mathrm{IQ}}{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bQ}}-1}{\cos \mathrm{\φ}}_{\mathrm{mI}}---\left(4\right)$

Wherein,

2V _{D, I}The amplitude of expression I road drive signal, 2V _{D, Q}The amplitude of expression Q road drive signal, 2 φ _IQPhase delay cell bias point in the expression DQPSK modulator, φ _BIThe bias point on expression I road, φ _BQThe bias point on expression Q road.

It is constant in the amplitude that keeps I road drive signal that the preferred embodiment provides, when making the average output power of DQPSK modulator get maximum, and the condition that amplitude satisfied of Q road drive signal.

Can find out that above-mentioned formula (3) and formula (4) are symmetrical.Like this; First via drive signal in method shown in Figure 3 is a Q road drive signal, when the second tunnel drive signal is I road drive signal, can adopt the mode of iteration; At first the amplitude of the I road drive signal after adjusted satisfies formula (3) according to above-mentioned steps S302; Regulate the amplitude of Q road drive signal then according to above-mentioned steps S304, can formula (3) be updated in the formula (4), the amplitude of the Q road drive signal after obtaining regulating among the step S304.And the like, finally can be preferably obtain after the number of times of repeating step S302 and step S304 reaches n time successively through following formula, the amplitude of the I road drive signal after the adjusting with regulate after the amplitude of Q road drive signal be:

${\cos \mathrm{\φ}}_{\mathrm{mI}}^n={\left[{\cos 2\mathrm{\φ}}_{\mathrm{IQ}}\right]}^{2n-1}{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bI}}-1}\right]}^n{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{2{\sin }^2{\mathrm{\φ}}_{\mathrm{bQ}}-1}\right]}^{n-1}{\cos \mathrm{\φ}}_{\mathrm{mQ}}^0---\left(5\right)$

${\cos \mathrm{\φ}}_{\mathrm{mQ}}^n={\left[{\cos 2\mathrm{\φ}}_{\mathrm{IQ}}\right]}^{2n}{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bI}}-1}\right]}^n{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{2{\sin }^2{\mathrm{\φ}}_{\mathrm{bQ}}-1}\right]}^n{\cos \mathrm{\φ}}_{\mathrm{mQ}}^0---\left(6\right)$

Wherein,

2V _{D, I}The amplitude of expression I road drive signal, 2V _{D, Q}The amplitude of expression Q road drive signal, 2 φ _IQPhase delay cell bias point in the expression DQPSK modulator, φ _BIThe bias point on expression I road, φ _BQThe bias point on expression Q road, n is the natural number greater than 0.

Can find out from above-mentioned formula (5) and formula (6), when n is tending towards infinity, 2V _{D, I}=2V _{D, Q}=2V _πPromptly through repeating above-mentioned steps S302 and step S304 successively, finally can so that the amplitude of two-way drive signal equate and be stabilized in 2V _πThereby realized amplitude control low-cost, drive signal reliably through self-regulating method; And in the process of regulating, only need gather and analyze the output optical signal power, the two-way drive signal amplitude that can realize importing the DQPSK modulator equates and equals 2V _π

Be the derivation that example is described above-mentioned formula in detail with the DQPSK transmitter system that comprises the DQPSK lithium niobate modulator below.The basic principle of DQPSK transmitter is: driver (comprising driver I and driver Q) amplifies the high-speed data signal of input; Carry out phase modulated through the DQPSK modulator then and obtain the DQPSK light signal, wherein the DQPSK lithium niobate modulator is formed according to the M-Z textural association by two M-Z type modulators.The structural representation of DQPSK transmitter is as shown in Figure 1.

Relational expression through analyzing the power output can obtain the DQPSK modulator and input power is following:

${\left|E_{\mathrm{out}}\right|}^2=\frac{{\left|E_i\right|}^2}{4}[{\sin }^2(\frac{{\mathrm{\πv}}_{d,I}}{{2V}_{\mathrm{\π}}}+{\mathrm{\φ}}_{\mathrm{bI}})+{\sin }^2(\frac{{\mathrm{\πv}}_{d,Q}}{{2V}_{\mathrm{\π}}}+{\mathrm{\φ}}_{\mathrm{bQ}})$

(1)

$-2\sin (\frac{{\mathrm{\πv}}_{d,I}}{{2V}_{\mathrm{\π}}}+{\mathrm{\φ}}_{\mathrm{bI}})\sin (\frac{{\mathrm{\πv}}_{d,Q}}{{2V}_{\mathrm{\π}}}+{\mathrm{\φ}}_{\mathrm{bQ}})\cos {2\mathrm{\φ}}_{\mathrm{IQ}}]$

Wherein, v _{D, I}, φ _BIModulation signal and the bias point of representing the I road respectively; v _{D, Q}, φ _BQModulation signal and the bias point of representing the Q road respectively.V _πThe half-wave voltage of expression DQPSK modulator, 2 φ _IQExpression phase delay cell bias point, | E _i| ²The power of the input signal of expression DQPSK modulator, | E _Out| ²The power of the output signal of expression DQPSK modulator.

Because the input data are random signals, then v _{D, I}=V _{D, I}And v _{D, I}=-V _{D, I}Probability is identical, v _{D, Q}=V _{D, Q}And v _{D, Q}=-V _{D, Q}Probability is identical, wherein V _{D, I}, V _{D, Q}The modulation amplitude of representing I road and Q road respectively, then the amplitude of I road and Q road drive signal is respectively 2V _{D, I}And 2V _{D, Q}Order

Can draw the average optical output power of DQPSK modulator according to formula (1) | E _Avg| ²For:

|E _avg| ²∝(2sin ²φ _bI-1)cos ²φ _mI-2cos2φ _IQsinφ _bIsinφ _bQcosφ _mQcosφ _mI

(2)

+cos ²φ _bI+sin ²φ _mQ+cos2φ _mQsin ²φ _bQ

In the DQPSK modulating system, divide equally on 0,2 π (this moment, the PHASE SEPARATION degree was maximum and identical) for four phase places of DQPSK signal that modulation is obtained, need the two-way drive signal amplitude to equate.Simultaneously, when they all equal 2 times of V _πThe time, the DQPSK modulators modulate is most effective and DQPSK modulation signal that obtain is best in quality.Therefore, input is advanced the two-way drive signal amplitude of DQPSK modulator and need control, make them be stabilized in 2V _π, i.e. V _{D, I}=V _{D, Q}=V _π

If keep the amplitude of Q road drive signal constant, regulate I road drive signal amplitude 2V _{D, I}, cos is then arranged ²φ _BI+ sin ²φ _MQ+ cos2 φ _MQSin ²φ _BQBe constant.According to the requirement of DQPSK signal transmission, in order to obtain best transmission performance, φ _BINeed equal 0.Therefore, under the general situation, (2sin ²φ _BI-1), thereby average light power | E _Avg| ²With φ _MIFor there is maximum in variable, obtains the maximum condition and be:

${\cos \mathrm{\φ}}_{\mathrm{mI}}=\frac{\cos {2\mathrm{\φ}}_{\mathrm{IQ}}{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bI}}-1}{\cos \mathrm{\φ}}_{\mathrm{mQ}}---\left(3\right)$

In like manner can obtain, keep the amplitude of I road drive signal constant, regulate Q road drive signal amplitude 2V _{D, Q}The time, average light power | E _Avg| ²With φ _MgObtaining peaked condition for variable is:

${\cos \mathrm{\φ}}_{\mathrm{mQ}}=\frac{\cos {2\mathrm{\φ}}_{\mathrm{IQ}}{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bQ}}-1}{\cos \mathrm{\φ}}_{\mathrm{mI}}---\left(4\right)$

If fixedly Q road drive signal amplitude is constant, regulate I road drive signal amplitude, make the output average light power be step to the maximum 1..If fixedly I road drive signal amplitude is constant, regulate Q road drive signal amplitude, make the output average light power be step to the maximum 2..Repeat successively n step 1. with step 2. after, note φ _MIAnd φ _MQBe respectively

Then have,

${\cos \mathrm{\φ}}_{\mathrm{mI}}^n={\left[{\cos 2\mathrm{\φ}}_{\mathrm{IQ}}\right]}^{2n-1}{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bI}}-1}\right]}^n{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{2{\sin }^2{\mathrm{\φ}}_{\mathrm{bQ}}-1}\right]}^{n-1}{\cos \mathrm{\φ}}_{\mathrm{mQ}}^0---\left(5\right)$

${\cos \mathrm{\φ}}_{\mathrm{mQ}}^n={\left[{\cos 2\mathrm{\φ}}_{\mathrm{IQ}}\right]}^{2n}{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bI}}-1}\right]}^n{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{2{\sin }^2{\mathrm{\φ}}_{\mathrm{bQ}}-1}\right]}^n{\cos \mathrm{\φ}}_{\mathrm{mQ}}^0---\left(6\right)$

In order to obtain best transmission performance, φ _BI, φ _BQAll need equal 0, Need equal π/4.Therefore, generally speaking, | cos2 φ _IQ|＜1,

Always satisfy.Can know by formula (5), (6), repeat repeatedly step 1. with step 2. after, φ _MIAnd φ _MQAll equal pi/2, i.e. V _{D, I}=V _{D, Q}=V _π

Fig. 4 is according to the control device 20 of the amplitude of the drive signal of the DQPSK modulator 10 of the embodiment of the invention, comprising: first adjustment module 202, second adjustment module 204, operational module 206, wherein:

First adjustment module 202; The current amplitude of first via drive signal of Q road drive signal and I road drive signal that is used for keeping importing DQPSK modulator 10 is constant; Regulate the average output power maximum of the current amplitude of the second tunnel drive signal in Q road drive signal and the I road drive signal up to the DQPSK modulator, and the amplitude of the current amplitude of the second tunnel drive signal after being set to regulate;

Second adjustment module 204 is used to keep the amplitude of the second tunnel drive signal constant for the amplitude after regulating, and the amplitude of regulating first via drive signal is maximum up to average output power, and the amplitude of the current amplitude of first via drive signal after being set to regulate;

Operational module 206 is used to control the operation that first adjustment module and second adjustment module repeat separately successively and makes the amplitude of Q road drive signal and I road drive signal all reach 2V _π, wherein, V _πHalf-wave voltage for the DQPSK modulator.

Control device in the DQPSK transmitter system among this embodiment passes through automatically to regulate the Q road drive signal of input DQPSK modulator and the amplitude of I road drive signal successively, thereby the amplitude that can stablize, realize accurately and rapidly the two-way drive signal all is stabilized in 2 times of V _π, improved the modulation efficiency of modulator preferably and obtained high-quality modulation signal, simultaneously cost is also very low, there is important meaning in system to the 40G dense wavelength division, improved whole system around performance.

Preferably, first via drive signal is a Q road drive signal, and the second tunnel drive signal is an I road drive signal; Perhaps, first via drive signal is an I road drive signal, and the second tunnel drive signal is a Q road drive signal.

Fig. 5 is the DQPSK transmitter system according to the embodiment of the invention, and this system comprises: DQPSK modulator 10, driver I 30, driver Q 40 and control device 20, wherein,

Driver I 30 is used under the control of first control signal that control device 20 is exported, and the I road drive signal of output DQPSK modulator 10 is to DQPSK modulator 10;

Driver Q 40 is used under the control of second control signal that control device 20 is exported, and the Q road drive signal of output DQPSK modulator 10 is to DQPSK modulator 10;

Control device 20 is used for repeating to adjust according to following rule the amplitude of one tunnel drive signal of Q road drive signal and the I road drive signal of input DQPSK modulator 10, makes the amplitude of Q road drive signal and I road drive signal all reach 2V _π: the Q road drive signal of maintenance input DQPSK modulator 10 and the current amplitude of the first via drive signal in the drive signal of I road are constant; Regulate the average output power maximum of the current amplitude of the second tunnel drive signal in Q road drive signal and the I road drive signal up to DQPSK modulator 10, and the amplitude of the current amplitude of the second tunnel drive signal after being set to regulate; The amplitude that keeps the second tunnel drive signal is constant for the amplitude after regulating, and the amplitude of regulating first via drive signal is maximum up to average output power, and the amplitude of the current amplitude of first via drive signal after being set to regulate; Wherein, V _πHalf-wave voltage for DQPSK modulator 10.

Preferably, above-mentioned first via drive signal is a Q road drive signal, and the second tunnel drive signal is an I road drive signal; Perhaps, first via drive signal is an I road drive signal, and the second tunnel drive signal is a Q road drive signal.

Preferably; As shown in Figure 6, control device 20 is a digital algorithm processing unit 202, and above-mentioned system also comprises: first D/A (i.e. a DAC), 50, second D/A (i.e. the 2nd DAC) 60, A/D converter (ADC) 70, photodetector (PD) 80; Wherein

Photodetector 80 is used to survey the output signal of DQPSK modulator 10;

A/D converter 70 is used for that photodetector 80 is surveyed the output conversion of signals that obtains and is digital output signal, and outputs to digital algorithm processing unit 202;

Digital algorithm processing unit 202 is used in the process of regulating, and confirms that according to the output signal of numeral the average output power of DQPSK modulator 10 reaches maximum;

First D/A 50 is used for converting first control signal of the numeral of digital algorithm processing unit 202 output into analog signal, and outputs to driver I 30;

Second D/A 60 is used for converting second control signal of the numeral of digital algorithm processing unit 202 output into analog signal, and outputs to driver Q 40.

The preferred embodiment realizes the control of the drive signal of DQPSK modulator in the DQPSK transmitter system based on digital processing, and it is simple flexibly to have high accuracy, high reliability, high-responsivity and a control loop, is beneficial to advantages such as debugging.

Preferably, digital algorithm processing unit 202 is DSP (Digital SignalProcessing, Digital Signal Processing) chip or FPGA (Field-Programmable GateArray, field programmable gate array) chip.Can reduce cost with dsp chip or fpga chip.

Below in conjunction with Fig. 6, describe the control method of drive signal of operation principle and the DQPSK modulator of DQPSK transmitter system in detail.

The light signal that sends from laser 100 is divided into I and Q two-way light after through a three-dB coupler 101.Data flow DATA_I is modulated on the light of I road by the MZ modulator 1 (102A) in the DQPSK modulator 10 after driver I 30 amplifies and obtains E _Iout, the amplitude of the I road drive signal of driver I 30 outputs is controlled by DriverI_Vpp_Control (being the first above-mentioned control signal).Data flow DATA_Q is modulated on the light of Q road by MZ modulator 2 (102B) after driver Q 40 amplifies and obtains E _Qout, the amplitude of the Q road signal of driver Q 40 outputs is controlled by DriverQ_Vpp_Control (being above-mentioned second control signal).E _IoutWith E _QoutAfter passing through phase delay cell (104A, 104B) the time-delay phase place of φ IQ and-φ IQ respectively, again by three-dB coupler 105 synthetic E _OutThe Output optical power signals collecting of utilizing high-precision adc 70 that built-in PD 80 is detected is advanced digital algorithm processing unit 202 (DSP or FPGA); Digital algorithm processing unit 202 is adjusted driver I and the I road drive signal of driver Q output and the amplitude of Q road drive signal according to preceding method adjustment DriverI_Vpp_Control and DriverQ_Vpp_Control with realization successively successively; And with the DriverI_Vpp_Control of numeral and DriverQ_Vpp_Control Control Driver I 30 and the I road drive signal of driver Q 40 outputs and the amplitude of Q road drive signal after a DAC 50 converts analog voltage signal into respectively; Make average optical output power maximum; After repeatedly repeating said process, can realize that finally driver I 30 and driver Q 40 amplitude output signals are stabilized in 2 times of V _π

From above description, can find out that the present invention has realized following technique effect:

(1) provide a kind of with low cost, be easy to realize, the control method and the device of the amplitude of the drive signal of DQPSK modulator in the DQPSK transmitter system that stability is higher;

(2) realize the modulation of high-quality DQPSK light signal, and improved the performance of whole DQPSK transmitter system.

Obviously, it is apparent to those skilled in the art that above-mentioned each module of the present invention or each step can realize with the general calculation device; They can concentrate on the single calculation element; Perhaps be distributed on the network that a plurality of calculation element forms, alternatively, they can be realized with the executable program code of calculation element; Thereby; Can they be stored in the storage device and carry out, and in some cases, can carry out step shown or that describe with the order that is different from here by calculation element; Perhaps they are made into each integrated circuit modules respectively, perhaps a plurality of modules in them or step are made into the single integrated circuit module and realize.Like this, the present invention is not restricted to any specific hardware and software combination.

The above is merely the preferred embodiments of the present invention, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (11)

1. the control method of drive signal amplitude in the differential quadrature phased shift keying DQPSK transmitter system is characterized in that, comprising:

Through maximizing the average output power of the DQPSK modulator in the said DQPSK transmitter system, the quadrature Q road drive signal of the said DQPSK modulator of control input and the amplitude of homophase I road drive signal all are stabilized in 2V _π, wherein, said V _πHalf-wave voltage for said DQPSK modulator.

2. method according to claim 1; It is characterized in that; Through maximizing the average output power of the DQPSK modulator in the said DQPSK transmitter system, the quadrature Q road drive signal of the said DQPSK modulator of control input and the amplitude of homophase I road drive signal all are stabilized in 2V _πComprise:

Step S302; The quadrature Q road drive signal of the said DQPSK modulator of maintenance input and the current amplitude of the first via drive signal in the drive signal of homophase I road are constant; The current amplitude of regulating the second tunnel drive signal in said Q road drive signal and the said I road drive signal is maximum up to the average output power of said DQPSK modulator, and the current amplitude of said the second tunnel drive signal is set to the amplitude after the said adjusting;

Step S304; The amplitude that keeps said the second tunnel drive signal is that the amplitude after the said adjusting is constant; The amplitude of regulating said first via drive signal is maximum up to said average output power, and the current amplitude of said first via drive signal is set to the amplitude after the said adjusting;

Repeating said steps S302 and said step S304 make the amplitude of said Q road drive signal and said I road drive signal all reach said 2V successively _π

3. method according to claim 2 is characterized in that, said first via drive signal is a said Q road drive signal, and said the second tunnel drive signal is a said I road drive signal; Perhaps, said first via drive signal is a said I road drive signal, and said the second tunnel drive signal is a said Q road drive signal.

4. method according to claim 3; It is characterized in that; Keep the amplitude of said Q road drive signal constant, the amplitude of regulating said I road drive signal comprises up to the average output power maximum of said DQPSK modulator: the amplitude of the I road drive signal after obtaining said adjusting through following formula:

Wherein,

2V _{D, I}The amplitude of representing said I road drive signal, 2V _{D, Q}The amplitude of representing said Q road drive signal, 2 φ _IQRepresent the phase delay cell bias point in the said DQPSK modulator, φ _BIThe bias point on expression I road, φ _BQThe bias point on expression Q road.

5. method according to claim 3; It is characterized in that; Keep the amplitude of said I road drive signal constant, the amplitude of regulating said Q road drive signal comprises up to the average output power maximum of said DQPSK modulator: the amplitude of the Q road drive signal after obtaining said adjusting through following formula:

Wherein,

2V _{D, I}The amplitude of representing said I road drive signal, 2V _{D, Q}The amplitude of representing said Q road drive signal, 2 φ _IQRepresent the phase delay cell bias point in the said DQPSK modulator, φ _BIThe bias point on expression I road, φ _BQThe bias point on expression Q road.

6. method according to claim 2; It is characterized in that; When said first via drive signal is a said Q road drive signal; When said the second tunnel drive signal is said I road drive signal, obtain after the number of times of repeating said steps S302 and said step S304 reaches n time successively the amplitude of the amplitude of the I road drive signal after the said adjusting and the Q road drive signal after the said adjusting through following formula:

${\cos \mathrm{\φ}}_{\mathrm{mI}}^n={\left[{\cos 2\mathrm{\φ}}_{\mathrm{IQ}}\right]}^{2n-1}{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bI}}-1}\right]}^n{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{2{\sin }^2{\mathrm{\φ}}_{\mathrm{bQ}}-1}\right]}^{n-1}{\cos \mathrm{\φ}}_{\mathrm{mQ}}^0;$

${\cos \mathrm{\φ}}_{\mathrm{mQ}}^n={\left[{\cos 2\mathrm{\φ}}_{\mathrm{IQ}}\right]}^{2n}{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{{2\sin }^2{\mathrm{\φ}}_{\mathrm{bI}}-1}\right]}^n{\left[\frac{{\sin \mathrm{\φ}}_{\mathrm{bI}}{\sin \mathrm{\φ}}_{\mathrm{bQ}}}{2{\sin }^2{\mathrm{\φ}}_{\mathrm{bQ}}-1}\right]}^n{\cos \mathrm{\φ}}_{\mathrm{mQ}}^0;$

Wherein,

2V _{D, I}The amplitude of representing said I road drive signal, 2V _{D, Q}The amplitude of representing said Q road drive signal, 2 φ _IQRepresent the phase delay cell bias point in the said DQPSK modulator, φ _BIThe bias point on expression I road, φ _BQThe bias point on expression Q road, n is the natural number greater than 0.

7. the control device of drive signal amplitude in the differential quadrature phased shift keying DQPSK transmitter system is characterized in that, comprising:

First adjustment module; The current amplitude of first via drive signal of quadrature Q road drive signal and homophase I road drive signal that is used for keeping importing said DQPSK modulator is constant; The current amplitude of regulating the second tunnel drive signal in said Q road drive signal and the said I road drive signal is maximum up to the average output power of said DQPSK modulator, and the current amplitude of said the second tunnel drive signal is set to the amplitude after the said adjusting;

Second adjustment module; The amplitude that is used to keep said the second tunnel drive signal is that the amplitude after the said adjusting is constant; The amplitude of regulating said first via drive signal is maximum up to said average output power, and the current amplitude of said first via drive signal is set to the amplitude after the said adjusting;

Operational module is used to control the operation that said first adjustment module and said second adjustment module repeat separately successively and makes the amplitude of said Q road drive signal and said I road drive signal all reach 2V _π, wherein, said V _πHalf-wave voltage for said DQPSK modulator.

8. control device according to claim 7 is characterized in that, said first via drive signal is a said Q road drive signal, and said the second tunnel drive signal is a said I road drive signal; Perhaps, said first via drive signal is a said I road drive signal, and said the second tunnel drive signal is a said Q road drive signal.

9. a differential quadrature phased shift keying DQPSK transmitter system is characterized in that, comprising: DQPSK modulator, driver I, driver Q and control device, wherein,

Said driver I is used under the control of first control signal that said control device is exported, and the I road drive signal of exporting said DQPSK modulator is to said DQPSK modulator;

Said driver Q is used under the control of second control signal that said control device is exported, and the Q road drive signal of exporting said DQPSK modulator is to said DQPSK modulator;

Said control device; Be used for repeating to adjust the amplitude of one tunnel drive signal of quadrature Q road drive signal and the homophase I road drive signal of the said DQPSK modulator of input, make the amplitude of said Q road drive signal and said I road drive signal all reach 2V according to following rule _π: the said Q road drive signal of the said DQPSK modulator of maintenance input and the current amplitude of the first via drive signal in the drive signal of said I road are constant; The current amplitude of regulating the second tunnel drive signal in said Q road drive signal and the said I road drive signal is maximum up to the average output power of said DQPSK modulator, and the current amplitude of said the second tunnel drive signal is set to the amplitude after the said adjusting; The amplitude that keeps said the second tunnel drive signal is that the amplitude after the said adjusting is constant; The amplitude of regulating said first via drive signal is maximum up to said average output power, and the current amplitude of said first via drive signal is set to the amplitude after the said adjusting;

Wherein, said V _πHalf-wave voltage for said DQPSK modulator.

10. system according to claim 9 is characterized in that, said control device is the digital algorithm processing unit, and said system also comprises: first D/A, second D/A, A/D converter and photodetector, wherein,

Said photodetector is used to survey the output signal of said DQPSK modulator;

Said A/D converter is used for that said photodetector is surveyed the said output conversion of signals that obtains and is digital said output signal, and outputs to said digital algorithm processing unit;

Said digital algorithm processing unit is used for the process in said adjusting, confirms that according to the said output signal of numeral the average output power of said DQPSK modulator reaches maximum;

Said first D/A is used for converting said first control signal of the numeral of said digital algorithm processing unit output into analog signal, and outputs to said driver I;

Said second D/A is used for converting said second control signal of the numeral of said digital algorithm processing unit output into analog signal, and outputs to said driver Q.

11. system according to claim 10 is characterized in that, said digital algorithm processing unit is Digital Signal Processing dsp chip or on-site programmable gate array FPGA chip.

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