CN101630977A - Device and method for locking demodulator phase in differential phase shift keying (DPSK) receiver - Google Patents

Device and method for locking demodulator phase in differential phase shift keying (DPSK) receiver Download PDF

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CN101630977A
CN101630977A CN 200910163008 CN200910163008A CN101630977A CN 101630977 A CN101630977 A CN 101630977A CN 200910163008 CN200910163008 CN 200910163008 CN 200910163008 A CN200910163008 A CN 200910163008A CN 101630977 A CN101630977 A CN 101630977A
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demodulator
phase
signal
dpsk
locking
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沈百林
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ZTE Corp
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Priority to PCT/CN2009/075326 priority patent/WO2011020260A1/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/66—Non-coherent receivers, e.g. using direct detection
    • H04B10/67—Optical arrangements in the receiver
    • H04B10/676—Optical arrangements in the receiver for all-optical demodulation of the input optical signal
    • H04B10/677—Optical arrangements in the receiver for all-optical demodulation of the input optical signal for differentially modulated signal, e.g. DPSK signals

Abstract

The invention provides a device and a method for locking a demodulator phase in a differential phase shift keying (DPSK) receiver. The device comprises a demodulator, a balance receiver, a multiplier and a demodulator control unit, wherein the demodulator is used for transmitting a DPSK optical signal to the balance receiver after adjusting the DPSK optical signal; the balance receiver is used for converting the demodulated optical signal into electrical signals by two photoelectric detectors, respectively separating one part of monitoring signals from two paths of electrical signals, transmitting the electrical signals to the multiplier and outputting the other part of monitoring signals after carrying out differential amplification; the multiplier is used for carrying out multiplication operation on the two paths of monitoring signals transmitted by the balance receiver and transmitting an operation result to the demodulator control unit; and the demodulator control unit monitors a feedback signal output by the multiplier and guides the phase adjusting direction of the demodulator according to the feedback signal. The invention directly realizes the mergence of the rough adjustment and the fine adjustment of the demodulator phase in the DPSK receiver and greatly optimizes the control scheme of the DPSK receiver.

Description

The apparatus and method of demodulator phase locking in a kind of DPSK receiver
Technical field
The present invention relates to the optical communication technique field, the apparatus and method of demodulator phase locking in particularly a kind of DPSK receiver.
Background technology
(Differential Phase Shift Keying, DPSK) modulation format is more superior than traditional sign indicating number type based on intensity modulated, has obtained extensive studies and application at present in high speed, long haul optical transmission for differential phase keying (DPSK).Phase modulation technique comprises coherent demodulation and realizes the reception of signal from two kinds of methods of coherent detection method.Wherein, coherent demodulation realizes complicated, simple relatively from the coherent detection method, utilize delay interferometer (Delay-interferometer, DLI) as demodulator (Demodulator), and then (Balanced Receiver BR) realizes the recovery of signal, as shown in Figure 1 to utilize balanced reciver.The phase place of DPSK system demodulator to the systematic function influence significantly, can be with reference to paper " OpticalPhase-Shift-Keyed Transmission " (the JOURNAL OF LIGHTWAVE TECHNOLOGY of A.H.Gnauck, VOL.23, NO.1, JANUARY 2005).The demodulator of DPSK receiver must guarantee phase matched, it is the consistent wavelength of the wavelength and the input signal of demodulator, otherwise can cause transmission performance damage serious, the control circuit of general using demodulator, by the temperature change demodulator wherein the length of an arm change phase place.The phase place of demodulator need accurately be locked as 0 or π in the DPSK receiver, to realize best performance.
At present the phase locking scheme comprises that phase place coarse adjustment and phase place finely tune two steps.The phase place coarse adjustment can utilize the two-way electric current of balanced reciver as feedback information, has realized the rough locking of phase place when current ratio is maximum; Phase place fine setting can utilize bit error rate information before the error correction, hour has promptly realized the accurate locking of phase place when the error rate.
Chinese patent CN200710143877.6, " DPSK light modulation signal receiving device and method " wherein also proposed a kind of method of how controlling demodulator, and particularly, peak detector is used to detect the peak value of the signal of telecommunication that is exaggerated; The time-delay control module is connected between optical fiber decoder and the peak detector, when peak detector detects peak value less than the signal of telecommunication that is amplified by limiting amplifier, and the time of delay of control optical fiber decoder.This is that the electrical signal amplitude peak value is adjusted demodulator after utilizing opto-electronic conversion.But monitoring of peak is subjected to dispersive influence bigger.
European patent EP 1643665A1, " Control of delay line interferometer " proposed the apparatus and method that a kind of FEC of utilization error code information is adjusted demodulator.But, relative with software algorithm complicated based on the phase locking specific implementation of error code information before the error correction, and need to consider to optimize and revise the coordination of control with other.
Therefore, need find a kind of method, adopt comparatively simple technical scheme just can overcome the bigger problem of cost that demodulator phase deviation causes in the DPSK receiver.
Summary of the invention
The objective of the invention is to, the device of demodulator phase locking in a kind of DPSK receiver is provided, can realize the fusion of the coarse adjustment of demodulator phase place and fine setting in the DPSK receiver, greatly optimized DPSK receiver controlling schemes.
Another object of the present invention is to, the method for demodulator phase locking in a kind of DPSK receiver is provided, can realize the fusion of the coarse adjustment of demodulator phase place and fine setting in the DPSK receiver, greatly optimized DPSK receiver controlling schemes.
The device of demodulator phase locking in the differential phase keying (DPSK) DPSK receiver of the present invention, comprise demodulator, balanced reciver, multiplier, demodulator control unit, wherein, described demodulator is sent to balanced reciver after being used for the DPSK light signal regulated; Described balanced reciver is used for the light signal after the demodulation is converted to the signal of telecommunication by two photodetectors, and isolates a part of monitor signal from two path signal, is sent to multiplier, another part monitor signal is carried out difference amplify back output; Described multiplier, the two-way monitor signal that described balanced reciver is sent carries out the phase multiplication, and operation result is sent to the demodulator control unit; Described demodulator control unit is used to monitor the feedback signal of multiplier output, and instructs the phase place adjustment direction of demodulator according to described feedback signal.
Whether wherein, described demodulator control unit instructs the phase place adjustment direction of demodulator to be according to described feedback signal: analyze phase place and lock, when non-locking, adjust the phase control parameter of adjuster, up to phase locking.
Wherein, described feedback signal is tending towards 0 or during less than reservation threshold, expression phase locking.
Wherein, described demodulator control unit is used for the temperature control phase skew by demodulator, and temperature control realizes by heater, and the magnitude of voltage on the phase deviation of demodulator and the heater square is directly proportional.
Wherein, described demodulator is used for the DPSK light signal is demodulated into the long mutually light signal of interference and interferes delustring signal mutually.
In addition, described balanced reciver comprises differential amplifier, exports after being used to transform the nonreturn to zero code differential electric signal.
The method of demodulator phase locking comprises the following steps: in the DPSK receiver of the present invention
Steps A: the DPSK light signal is regulated the back be converted to the signal of telecommunication, and from two path signal, isolate a part of monitor signal, be sent to multiplier, another part monitor signal is carried out difference amplify back output by two photodetectors;
Step B: multiplier carries out the phase multiplication to the two-way monitor signal that described balanced reciver sends, and operation result is exported as feedback signal;
Step C: monitor the feedback signal of multiplier output, and instruct the phase place of demodulator to adjust direction according to described feedback signal.
Wherein, in described step C, instruct the phase place of demodulator to adjust direction according to described feedback signal and be, analyze phase place and whether lock, when non-locking, adjust the phase control parameter of adjuster, up to phase locking.
In addition, in described step C, described feedback signal is tending towards 0 or during less than reservation threshold, expression phase locking.
In addition, the temperature control phase skew by demodulator, temperature control realize by heater, and the magnitude of voltage on the phase deviation of demodulator and the heater square is directly proportional.
The invention has the beneficial effects as follows: according to the apparatus and method of demodulator phase locking in the DPSK receiver of the present invention, avoided input optical power to change and detected current factor causing the demodulator mistuning to put in order effect according to change in pattern, do not need the preceding error code information of error correction, also can not produce aliasing to other system optimizing control of DPSK receiver disturbs, directly realized the fusion of the coarse adjustment of demodulator phase place and fine setting in the DPSK receiver, greatly optimize DPSK receiver controlling schemes, improved the engineering practicability of DPSK system greatly.
Description of drawings
Fig. 1 is a DPSK system receiver principle assumption diagram;
Fig. 2 is the structural representation of the device of demodulator phase locking in the DPSK receiver of the present invention;
Fig. 3 is the flow chart of the method for demodulator phase locking in the DPSK receiver of the present invention.
Embodiment
Below, 1～3 apparatus and method of describing demodulator phase locking in the DPSK receiver of the present invention in detail with reference to the accompanying drawings.
As shown in Figure 2, the structural representation of the device of demodulator phase locking in the DPSK receiver of the present invention, this device comprises: demodulator 1, balanced reciver 2, multiplier 3, demodulator control unit 4.
Wherein, demodulator 1 is used for the DPSK light signal is demodulated into the long mutually light signal of interference and interferes delustring signal mutually, then the light signal that adjusts is sent to balanced reciver 2.Wherein, demodulator can adopt free space Michelson's interferometer technology to realize, also can adopt the optical fiber mach Zehnder interferometer to realize, they are ripe optical device product.In addition, the temperature of demodulator control can realize phase deviation, and temperature control realizes by heater, and the magnitude of voltage on the phase deviation of demodulator just and the heater square is directly proportional.
Balanced reciver 2, comprise photodetector 21 (PD1) and photodetector 22 (PD2) and differential amplifier 23, light signal after the demodulation is converted to the signal of telecommunication by two photodetectors, and isolates a part of monitor signal respectively from two path signal, is sent to multiplier 3; A part of monitor signal sent into export after differential amplifier transforms nonreturn to zero code (NRZ) differential electric signal; Wherein, the transmission path that is sent to the two-way monitoring signal of telecommunication of multiplier 3 should equate as far as possible, avoids extra phase error.
In addition, demodulator and balanced reciver can be the separate type optical devices, also can be to integrate.
Multiplier 3, the two-way monitor signal that balanced reciver 2 is sent carries out the phase multiplication, and operation result is sent to demodulator control unit 4.
Multiplier can adopt the AD835 chip of ANALOG DEVICES company, and bandwidth is 250MHz.The output of multiplier is as feedback signal.
Demodulator control unit 4 comprises digital simulation converter and temperature-control circuit, is used to monitor the feedback signal of multiplier output, and utilizes this feedback signal to instruct the phase place of demodulator to adjust direction.Wherein, digital analog converter is used to monitor feedback signal; Temperature-control circuit is used to adjust the phase place of demodulator.
The generation principle of feedback signal is as follows:
According to the theory of demodulation of DPSK, the two-way of demodulator is output as:
E → ( out ) = 1 2 E 1 ( t - T ) + E 1 ( t ) j E 1 ( t - T ) - j E 1 ( t )
Wherein
Figure G2009101630089D00042
Be illustrated in t dpsk signal constantly, E 1(t-T) expression postpones the dpsk signal of 1 bit,
Figure G2009101630089D00043
Be the phase place of dpsk signal, j represents plural number, has ignored frequency dependence item e herein J ω t
The phase difference of dpsk signal adjacent bit
Figure G2009101630089D00051
Value is 0 or π, supposes that phase error is δ.The output signal of multiplier is as the feedback signal of control loop, the derivation of feedback signal is specially following formula, monitor signal is output as the square law detection from photodetector, be the signal absolute value square, signal is expressed as plural form, respectively two-way is carried out multiplication cross, eliminate the influence of time t, the phase difference of considering the adjacent bit of dpsk signal is 0 or π, draws only relevant with phase error feedback signal at last:
| E 1 ( t - T ) + E 1 ( t ) | 2 | j E 1 ( t - T ) - j E 1 ( t ) | 2
Figure G2009101630089D00053
Figure G2009101630089D00054
Figure G2009101630089D00055
Figure G2009101630089D00056
Figure G2009101630089D00057
Figure G2009101630089D00058
= 4 sin 2 ( δ )
As can be seen from the above equation when phase error is 0, i.e. demodulator phase locking, the output feedback signal of multiplier also is 0.Along with phase error increases, the output of multiplier also increases.Specific explanations is as follows: when increasing the voltage of demodulator, if feedback signal increases, the phase control anisotropy of demodulator is described, should reduces demodulator voltage; In like manner,,, illustrate that adjustment is in the right direction, should continue to increase the voltage of demodulator, be tending towards 0 or less than certain threshold value until feedback signal if feedback signal reduces when the voltage that increases demodulator.
As shown in Figure 3, for the present invention realizes the method flow diagram of demodulator phase locking in the DPSK receiver, this method may further comprise the steps:
Step 100: the DPSK light signal is regulated the back be converted to the signal of telecommunication, and from two path signal, isolate a part of monitor signal, be sent to multiplier, another part monitor signal is carried out difference amplify back output by two photodetectors;
Step 200: multiplier carries out the phase multiplication to the two-way monitor signal that described balanced reciver sends, and operation result is exported as feedback signal;
Step 300: monitor the feedback signal of multiplier output, and instruct the phase place of demodulator to adjust direction according to this feedback signal.
Wherein, in step 300, instruct the phase place adjustment direction of demodulator to be according to feedback signal: to analyze phase place and whether lock, when non-locking, adjust the phase control parameter of adjuster, up to phase locking.This feedback signal is tending towards 0 or during less than reservation threshold, expression phase locking.
In addition, come control phase skew by the temperature of control demodulator, temperature control realizes by heater, and the magnitude of voltage on the phase deviation of demodulator and the heater square is directly proportional.
In sum, apparatus and method according to demodulator phase locking in the DPSK receiver of the present invention, compared with prior art, avoided input optical power to change and detected current factor causing the demodulator mistuning to put in order effect according to change in pattern, do not need the preceding error code information of error correction, also can not produce aliasing to other system optimizing control of DPSK receiver disturbs, directly realized the fusion of the coarse adjustment of demodulator phase place and fine setting in the DPSK receiver, greatly optimize DPSK receiver controlling schemes, improved the engineering practicability of DPSK system greatly.
More than be in order to make those of ordinary skills understand the present invention; and to detailed description that the present invention carried out; but can expect; in the scope that does not break away from claim of the present invention and contained, can also make other variation and modification, these variations and revising all in protection scope of the present invention.

Claims (10)

1. the device of demodulator phase locking in the differential phase keying (DPSK) DPSK receiver is characterized in that, comprises demodulator, balanced reciver, multiplier, demodulator control unit, wherein,
Described demodulator is sent to balanced reciver after being used for the DPSK light signal regulated;
Described balanced reciver is used for the light signal after the demodulation is converted to the signal of telecommunication by two photodetectors, and isolates a part of monitor signal from two path signal, is sent to multiplier, another part monitor signal is carried out difference amplify back output;
Described multiplier, the two-way monitor signal that described balanced reciver is sent carries out the phase multiplication, and operation result is sent to the demodulator control unit;
Described demodulator control unit is used to monitor the feedback signal of multiplier output, and instructs the phase place adjustment direction of demodulator according to described feedback signal.
2. the device of demodulator phase locking in the DPSK receiver as claimed in claim 1, it is characterized in that, whether described demodulator control unit instructs the phase place of demodulator to adjust direction according to described feedback signal: analyze phase place and lock, when non-locking, adjust the phase control parameter of adjuster, up to phase locking.
3. the device of demodulator phase locking is characterized in that in the DPSK receiver as claimed in claim 2, and described feedback signal is tending towards 0 or during less than reservation threshold, expression phase locking.
4. as the device of demodulator phase locking in each described DPSK receiver in the claim 1 to 3, it is characterized in that, described demodulator control unit, be used for temperature control phase skew by demodulator, temperature control realizes by heater, and the magnitude of voltage on the phase deviation of demodulator and the heater square is directly proportional.
5. as the device of demodulator phase locking in each described DPSK receiver in the claim 1 to 3, it is characterized in that described demodulator is used for the DPSK light signal is demodulated into the long mutually light signal of interference and interferes delustring signal mutually.
6. as the device of demodulator phase locking in each described DPSK receiver in the claim 1 to 3, it is characterized in that described balanced reciver comprises differential amplifier, export after being used to transform the nonreturn to zero code differential electric signal.
7. the method for demodulator phase locking in the DPSK receiver is characterized in that, comprises the following steps:
Steps A: the DPSK light signal is regulated the back be converted to the signal of telecommunication, and from two path signal, isolate a part of monitor signal, be sent to multiplier, another part monitor signal is carried out difference amplify back output by two photodetectors;
Step B: multiplier carries out the phase multiplication to the two-way monitor signal that described balanced reciver sends, and operation result is exported as feedback signal;
Step C: monitor the feedback signal of multiplier output, and instruct the phase place of demodulator to adjust direction according to described feedback signal.
8. the method for demodulator phase locking in the DPSK receiver as claimed in claim 7, it is characterized in that, in described step C, instruct the phase place adjustment direction of demodulator to be according to described feedback signal, whether analyze phase place locks, when non-locking, adjust the phase control parameter of adjuster, up to phase locking.
9. the method for demodulator phase locking is characterized in that in the DPSK receiver as claimed in claim 8, and in described step C, described feedback signal is tending towards 0 or during less than reservation threshold, expression phase locking.
10. as the method for demodulator phase locking in each described DPSK receiver in the claim 7 to 9, it is characterized in that, temperature control phase skew by demodulator, temperature control realize by heater, and the magnitude of voltage on the phase deviation of demodulator and the heater square is directly proportional.
CN 200910163008 2009-08-19 2009-08-19 Device and method for locking demodulator phase in differential phase shift keying (DPSK) receiver Pending CN101630977A (en)

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PCT/CN2009/075326 WO2011020260A1 (en) 2009-08-19 2009-12-04 Device and method for locking demodulator phase in differential phase shift keying receiver

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