CN108809438B - A time difference compensation method and device - Google Patents

Abstract

The invention discloses a time difference compensation method, which comprises the steps of obtaining a first signal and a second signal, and determining a forward interpolation result and a backward interpolation result of the second signal; determining a first correlation of a first signal and a second signal, a second correlation of a differential value of the first signal and a differential value of the second signal, a third correlation of a differential value of the first signal and a differential value of a forward interpolation result of the second signal, and a fourth correlation of a differential value of the first signal and a differential value of a backward interpolation result of the second signal, respectively; adjusting the time difference compensation value according to a preset adjustment rule and a first difference value of the second correlation and the first correlation, and/or a second difference value of the third correlation and the first correlation, and/or a third difference value of the fourth correlation and the first correlation; the time difference compensation value is used for adjusting the time difference of the first signal and the second signal. The invention also discloses a time difference compensation device.

Description

A time difference compensation method and device

technical field

The present invention relates to the technical field of optical communication, and in particular, to a time difference compensation method and device.

Background technique

In the high-speed optical communication network environment, the coherent optical receiver is usually used to receive and process the photoelectric signal; the coherent optical receiver mixes the received optical signal with the optical signal output by the local laser, and divides it into an X-biased positive in-phase signal. (XI), X partial front quadrature signal (XQ), Y partial front in-phase signal (YI) and Y partial front quadrature signal (YQ), and then the four signals are respectively photoelectrically converted (O/E, Optical to electrical), power amplification (TIA, Trans-Impedance Amplifier) and analog-to-digital conversion (ADC, Analog-to-Digital Convert), and finally into the digital signal processor (DSP, Digital Signal Processor).

Ideally, XI and XQ, YI and YQ should be time-synchronized; however, due to the difference of devices in the signal path, the synchronization cannot be guaranteed, and this nonlinear distortion has a great impact on the performance of coherent optical receivers.

The solution to the traditional coherent optical receiver is to calibrate the front-end installation of the coherent optical receiver, measure the time difference between the in-phase signal and the quadrature (IQ) signal, and set the time difference compensation value after the ADC for time difference compensation. . This method works well when the coherent optical receiver is first used, but with the aging of the coherent optical receiver device or the change of the environment, the time difference between the IQ signals will change dynamically. The time difference compensation value set during calibration The effect will gradually deteriorate.

Therefore, how to obtain the time difference of the IQ signal, adjust the time difference compensation value, and improve the effect of the time difference compensation of the IQ signal is an urgent problem to be solved.

SUMMARY OF THE INVENTION

In view of this, the embodiments of the present invention are expected to provide a time difference compensation method and apparatus, which can acquire the time difference of an IQ signal, adjust the time difference compensation value, and improve the time difference compensation effect.

In order to achieve the above object, the technical scheme of the present invention is achieved in this way:

An embodiment of the present invention provides a time difference compensation adjustment method, the method includes:

acquiring a first signal and a second signal, and determining a forward interpolation result and a backward interpolation result of the second signal;

Determine the first correlation between the first signal and the second signal, the second correlation between the difference value of the first signal and the difference value of the second signal, and the difference value of the first signal and the first signal. The third correlation of the difference value of the forward interpolation result of the two signals, and the fourth correlation of the difference value of the first signal and the difference value of the backward interpolation result of the second signal;

According to the first difference between the second correlation and the first correlation, and/or the second difference between the third correlation and the first correlation, and/or the third difference between the fourth correlation and the first correlation value, adjust the time difference compensation value according to the preset adjustment rule; the time difference compensation value is used to adjust the time difference between the first signal and the second signal.

In the above solution, the first correlation between the first signal and the second signal, the second correlation between the differential value of the first signal and the differential value of the second signal, the A third correlation of the difference value with the difference value of the result of the forward interpolation of the second signal, and a fourth correlation of the difference value of the first signal with the difference value of the result of the backward interpolation of the second signal, including :

Determining the correlation between the first signal after passing through the low-pass filter and the second signal after passing through the low-pass filter as the first correlation;

Determining the correlation between the first signal passing through the high-pass filter and the second signal passing through the high-pass filter as the second correlation;

The correlation between the first signal after passing through the high-pass filter and the forward interpolation result of the second signal after passing through the high-pass filter is determined as the third correlation;

The correlation between the high-pass filter of the first signal and the back-interpolation result of the second signal after the high-pass filter is determined as the fourth correlation.

In the above solution, the first correlation between the first signal and the second signal, the second correlation between the differential value of the first signal and the differential value of the second signal, the A third correlation of the difference value with the difference value of the result of the forward interpolation of the second signal, and a fourth correlation of the difference value of the first signal with the difference value of the result of the backward interpolation of the second signal, including :

Determining the average value of the correlations between the preset accumulation times of the first signal after passing through the low-pass filter and the second signal passing through the low-pass filter as the first correlation;

Determining the average value of the correlation between the first signal of the preset number of accumulations after passing through the high-pass filter and the second signal after passing through the high-pass filter, as the second correlation;

Determine the third correlation as the average value of the correlation between the first signal of the preset number of accumulations after passing through the high-pass filter and the forward interpolation result of the second signal after passing through the high-pass filter;

The fourth correlation is determined as the average value of the correlation between the first signal of the preset accumulation times after passing through the high-pass filter and the backward interpolation result of the second signal passing through the high-pass filter.

In the above solution, the adjustment of the time difference compensation value according to the preset adjustment rule includes:

When the first difference is greater than a first preset threshold, the second difference is greater than a second preset threshold, and the third difference is less than the second threshold, increasing the current time difference compensation value;

When the first difference is greater than the first preset threshold, the second difference is less than the second preset threshold, and the third difference is greater than the second preset threshold, reduce the current time difference compensation value.

In the above solution, the determining of the forward interpolation result and the backward interpolation result of the second signal includes:

A time interval smaller than the ADC sampling period to which the second signal belongs is taken as an interpolation step size, and forward interpolation processing and backward interpolation processing are performed on the second signal.

In the above solution, the first signal and the second signal are in-phase signals and quadrature signals of the same polarization plane, respectively.

An embodiment of the present invention further provides a time difference compensation device, the device includes: a first determination module, a second determination module, and an adjustment module; wherein,

The first determining module is configured to acquire a first signal and a second signal, and determine a forward interpolation result and a backward interpolation result of the second signal;

The second determining module is configured to respectively determine the first correlation between the first signal and the second signal, the second correlation between the difference value of the first signal and the difference value of the second signal, the first correlation The third correlation between the difference value of a signal and the difference value of the result of forward interpolation of the second signal, and the fourth correlation between the difference value of the first signal and the difference value of the result of backward interpolation of the second signal sex;

The adjustment module is configured to adjust according to the first difference between the second correlation and the first correlation, and/or the second difference between the third correlation and the first correlation, and/or the fourth correlation and the first correlation. For the third difference value of the correlation, the time difference compensation value is adjusted according to a preset adjustment rule; the time difference compensation value is used to adjust the time difference between the first signal and the second signal.

In the above scheme, the second determination module is specifically used for:

Determining the correlation between the first signal after passing through the low-pass filter and the second signal after passing through the low-pass filter as the first correlation;

Determining the correlation between the first signal passing through the high-pass filter and the second signal passing through the high-pass filter as the second correlation;

The correlation between the first signal after passing through the high-pass filter and the forward interpolation result of the second signal after passing through the high-pass filter is determined as the third correlation;

The correlation between the high-pass filter of the first signal and the back-interpolation result of the second signal after the high-pass filter is determined as the fourth correlation.

In the above solution, the second determination module is specifically configured to: determine the average value of the correlation between the first signal of the preset accumulation times after passing through the low-pass filter and the second signal after passing through the low-pass filter. is the first correlation;

Determining the average value of the correlation between the first signal of the preset number of accumulations after passing through the high-pass filter and the second signal after passing through the high-pass filter, as the second correlation;

Determine the third correlation as the average value of the correlation between the first signal of the preset number of accumulations after passing through the high-pass filter and the forward interpolation result of the second signal after passing through the high-pass filter;

The fourth correlation is determined as the average value of the correlation between the first signal of the preset accumulation times after passing through the high-pass filter and the backward interpolation result of the second signal passing through the high-pass filter.

In the above scheme, the adjustment module is specifically used for:

When the first difference is greater than a first preset threshold, the second difference is greater than a second preset threshold, and the third difference is less than the second threshold, increasing the current time difference compensation value;

When the first difference is greater than the first preset threshold, the second difference is less than the second preset threshold, and the third difference is greater than the second preset threshold, reduce the current time difference compensation value.

In the above scheme, the first determination module is specifically used for:

A time interval smaller than the sampling period of the analog-to-digital conversion ADC to which the second signal belongs is taken as an interpolation step size, and forward interpolation processing and backward interpolation processing are performed on the second signal.

In the above solution, the first signal and the second signal are in-phase signals and quadrature signals of the same polarization plane, respectively.

The time difference compensation method and device provided by the embodiments of the present invention acquire a first signal and a second signal, and determine a forward interpolation result and a backward interpolation result of the second signal; determine the first signal and the second signal respectively. a correlation, a second correlation between the difference value of the first signal and the difference value of the second signal, the first correlation between the difference value of the first signal and the difference value of the forward interpolation result of the second signal Three correlations, and a fourth correlation between the differential value of the first signal and the differential value of the backward interpolation result of the second signal; according to the first difference between the second correlation and the first correlation, and/ Or the second difference between the third correlation and the first correlation, and/or the third difference between the fourth correlation and the first correlation, according to the preset adjustment rule, adjust the time difference compensation value; the time difference compensation value is used to adjust the time difference between the first signal and the second signal; in this way, through the first signal and the second signal, the time difference related parameters of the first signal and the second signal are determined, and the time difference compensation value is performed according to the preset rule. Adjustment to realize real-time time difference compensation and improve the effect of time difference compensation.

Description of drawings

1 is a schematic flowchart of a time difference compensation method according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the composition and structure of an existing coherent optical receiver front end according to an embodiment of the present invention;

3 is a schematic diagram of the setting position of the time difference compensation adjustment device according to the embodiment of the present invention;

4 is a schematic diagram of a logical structure of correlation difference measurement according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a time difference compensation device according to an embodiment of the present invention.

Detailed ways

In this embodiment of the present invention, a first signal and a second signal are acquired, and a forward interpolation result and a backward interpolation result of the second signal are determined; the first correlation of the first signal and the second signal, the The second correlation between the differential value of the first signal and the differential value of the second signal, the third correlation between the differential value of the first signal and the differential value of the forward interpolation result of the second signal, and the the fourth correlation between the differential value of the first signal and the differential value of the backward interpolation result of the second signal; according to the first difference between the second correlation and the first correlation, and/or the third correlation and The second difference value of the first correlation and/or the third difference value between the fourth correlation and the first correlation, according to a preset adjustment rule, adjust the time difference compensation value; the time difference compensation value is used to adjust the time difference compensation value. The time difference between the first signal and the second signal.

The present invention will be described in further detail below in conjunction with the embodiments.

The time difference compensation method provided by the embodiment of the present invention, as shown in FIG. 1 , includes:

Step 101: Acquire a first signal and a second signal, and determine a forward interpolation result and a backward interpolation result of the second signal;

The block diagram of the front end of the existing coherent optical receiver is shown in Figure 2; the optical signal received by the coherent optical receiver is mixed with the optical signal output by the local laser, and divided into XI, XQ, YI, and YQ four channels, and then O /E, TIA and ADC, and finally enter the DSP; the traditional time difference compensation can be performed by the DSP; according to the calibration at the front-end installation of the coherent optical receiver, the time difference between the IQ signals can be measured; the maintenance personnel can calculate the time difference in the DSP according to the time difference Set the time difference compensation value, which is compensated by DSP;

Here, the first signal and the second signal after the traditional time difference compensation can be obtained, wherein the first signal and the second signal are the in-phase (I) signal and the quadrature (Q) signal of the same polarization plane respectively; Connect a bypass line or the like on the IQ signal communication line to obtain the first signal and the second signal;

After acquiring the first signal and the second signal, interpolation processing can be performed on the second signal, that is, the Q signal; data processing can be performed by the arithmetic unit in the DSP; it is assumed that the function of the Q signal is Q(t), where t is a time variable. First, the Q(t) data can be forward-interpolated to obtain the forward-interpolated data of the second signal Q _pre =Q(t-dt), and then the input Q(t) data can be backward-interpolated. Interpolate to obtain backward interpolation data of the second signal to obtain Q _pst =Q(t+dt).

Further, the difference step size dt may take a fixed value smaller than the ADC sampling period Ts, generally Ts/3.

In practical applications, methods such as Lagrangian interpolation method may be used to perform the interpolation calculation of the second signal.

Step 102: Determine the first correlation between the first signal and the second signal, the second correlation between the difference value of the first signal and the difference value of the second signal, and the difference value of the first signal and the difference value of the second signal. a third correlation of the difference value of the forward interpolation result of the second signal, and a fourth correlation of the difference value of the first signal and the difference value of the backward interpolation result of the second signal;

Here, data processing can be performed by the arithmetic unit in the DSP; the first signal is an I signal, and the second signal is a Q signal; the first correlation λ between the I signal and the Q signal can be calculated; after calculating the difference between the I signal and the Q signal The second _{correlation γ after} the difference of γ _p st; wherein, the difference can be in the form of the expression f'(n)=f(n+1)-f(n), where f'(n) represents the next signal data f(n+1) Difference from the previous signal data f(n).

Further, it can be generally considered that the differential operation is a simplified high-pass filter; the correlation between the I signal after passing through the low-pass filter and the Q signal after passing through the low-pass filter can be determined as the first correlation λ; I The correlation between the signal after the high-pass filter and the Q signal after the high-pass filter is determined as the second correlation γ; the correlation between the I signal after the high-pass filter and the forward interpolation result of the Q signal after the high-pass filter is γ _pre , determined as the third correlation; the correlation between the I signal after passing through the high-pass filter and the backward interpolation result of the Q signal after passing through the high-pass filter is determined as the fourth correlation γ _pst ; the existing time difference measurement usually requires a higher The high-pass filter and the low-pass filter can improve the adaptability to the frequency offset, and even a small frequency offset can achieve high measurement accuracy; the high-pass filter described here Filters and low-pass filters can use common structures, such as a 2- or 3-tap FIR filter.

Further, the correlation value of the preset accumulation times N can be accumulated, and the average value is taken as the final correlation value; the I signal of the preset accumulation times N is subjected to a low-pass filter and the second signal is subjected to a low-pass filter. The average value of the correlation after the filter is determined as the first correlation λ; the average value of the correlation between the I signal after the high-pass filter and the Q signal after the high-pass filter for the preset accumulation times N is determined as the first Two correlations γ; the I signal of the preset accumulation times N is passed through the high-pass filter and the Q signal forward interpolation result is passed through the high-pass filter. The average value of the correlation is determined as the third correlation γ _pre ; the preset accumulation The average value of the correlation between the I signal of the number N and the backward interpolation result of the Q signal after the high-pass filter is passed through the high-pass filter, and is determined as the fourth correlation γ _pst ; wherein the selected preset accumulation number N is to adapt to the IQ time difference Since the device characteristics change very slowly, as long as a set of results can be output every 0.1s, it can keep up with the change of IQ time difference, so a larger N value, such as 2 ¹⁴ , can be selected to improve the average effect.

Step 103: According to the first difference between the second correlation and the first correlation, and/or the second difference between the third correlation and the first correlation, and/or the difference between the fourth correlation and the first correlation For the third difference, the time difference compensation value is adjusted according to a preset adjustment rule; the time difference compensation value is used to adjust the time difference between the first signal and the second signal;

Here, the first difference δ between the second correlation γ and the first correlation λ, the second difference δ _pre between the third correlation γ _pre and the first correlation λ, and the fourth correlation γ _pst may be determined first. The third difference δ _pst with the first correlation λ; the first correlation λ can be subtracted from the second correlation γ to obtain the first difference δ; the first correlation λ is subtracted from the third correlation γ _pre , obtain the second difference δ _pre ; subtract the first correlation λ from the fourth correlation γ _pst to obtain the third difference δ _pst ;

The preset adjustment rule may be to adjust the time difference compensation value according to the comparison result of the first difference, the second difference and the third difference and a preset threshold; the first difference, the second difference The comparison result between the difference value and the third difference value and the threshold value reflects the time difference between the first signal and the second signal, so the time difference compensation value can be adjusted according to the comparison result. The adjusting the time difference compensation value according to the preset adjustment rule includes: when the first difference δ is greater than the first preset threshold, the second difference δ _pre is greater than the second preset threshold, and the third difference δ _pst is less than the first When there are two preset thresholds, the current time difference compensation value is increased; when the first difference δ is greater than the first preset threshold, the second difference δ _pre is smaller than the second preset threshold, and the third difference δ _pst is greater than the second preset When the threshold is set, reduce the current time difference compensation value;

Wherein, the first preset threshold and the second preset threshold may be determined through experimental data, wherein the first preset threshold may be 5/10000, the second preset threshold may be 3/1000, the The step size of the time difference compensation adjustment can be 1/512 of the ADC sampling period;

Here, since the first correlation is the first correlation between the I signal after passing through the low-pass filter and the Q signal after passing through the low-pass filter as the comparison base; in this way, compared with the existing comparison base of 0, it is possible to improve the For the tolerance of signal phase difference, the time difference compensation method provided by the embodiment of the present invention may be used before phase difference compensation.

In this way, the adjustment of the time difference compensation value is completed, and the time difference compensation is performed on the first signal and the second signal according to the time difference compensation value; and the time difference between the first signal and the second signal is continuously adjusted by this real-time feedback method; thereby improving the The synchronization of the first signal and the second signal is achieved.

The positive effects produced by the present invention are described in further detail below in conjunction with specific examples;

The time difference compensation method provided by the embodiment of the present invention can separately measure the time difference of XI, XQ, YI and YQ after the time difference compensation is performed by the traditional time difference compensation method, and then adjust the time difference compensation value according to the result of the time difference measurement, so as to adjust the time difference more accurately. Time difference; a time difference compensation adjustment device can be set for XI and XQ, YI and YQ respectively. The setting positions of each time difference compensation adjustment device can be as shown in Figure 3; the time difference compensation adjustment device can be set after the traditional time difference compensation to adjust the time difference compensation value;

The logical structure diagram of measuring the correlation difference in the time difference compensation adjustment device can be shown in Figure 4:

There are two identical low-pass filters (LPF, Low Pass Filter) and four identical high-pass filters (HPF, High Pass Filter) in the logic structure diagram; LPF and HPF can use common structures, and the measured effect is only A 2- or 3-tap FIR filter is sufficient; a suitable filter can improve the performance of the time difference measurement module;

There are two identical interpolation modules in the logical structure diagram, one is ITP _pre , which is responsible for forward interpolation of the input Q(t) data to obtain Q _pre =Q(t-dt); the other is ITPpst, which is responsible for the The input Q(t) data is back-interpolated to obtain Q _pst =Q(t+dt); where dt can take a fixed value smaller than the ADC sampling period Ts, and can take Ts/3;

After I and Q are filtered by LPF respectively, they are multiplied and accumulated for N times to obtain the correlation value λ;

After I and Q _pre are filtered by HPF respectively, they are multiplied and accumulated for N times and averaged to obtain the correlation value γ _pre ; then λ is subtracted to obtain δ _pre ;

After I and Q are filtered by HPF respectively, they are multiplied and accumulated N times to obtain the correlation value γ, and then subtract λ to obtain δ;

After I and Q _pst are filtered by HPF respectively, they are multiplied and accumulated N times for averaging to obtain the correlation value γ _pst , and then subtract λ to obtain δ _pst ;

For each processing of N groups of IQ data, a group of δ _pre , δ and δ _pst can be obtained. The selected N value should adapt to the change speed of the IQ time difference; the device characteristics change very slowly, as long as a group of results can be output every 0.1s, it can keep up. The IQ time difference has changed, so a larger N value can be selected to improve the average effect;

If |δ|>th1, and |δ _pre |>th2, and |δ _pst |<th2, increase the current time difference compensation value;

If |δ|>th1, and |δ _pre |<th2, and |δ _pst |>th2, reduce the current time difference compensation value;

Wherein, th1 and th2 are the first preset threshold and the second preset threshold respectively, which can be determined by experimental data, th1 can be 5/10000, th2 can be 3/1000, and the step size of the time difference compensation value can be 1/512 of the ADC sampling period.

The time difference compensation device provided by the embodiment of the present invention, as shown in FIG. 5 , the device includes: a first determination module 51, a second determination module 52, and an adjustment module 53; wherein,

The first determination module 51 is configured to acquire the first signal and the second signal, and determine the forward interpolation result and the backward interpolation result of the second signal;

The block diagram of the front end of the existing coherent optical receiver is shown in Figure 2; the optical signal received by the coherent optical receiver is mixed with the optical signal output by the local laser, and divided into XI, XQ, YI, and YQ four channels, and then O /E, TIA and ADC, and finally enter the DSP; the traditional time difference compensation can be performed by the DSP; according to the calibration at the front-end installation of the coherent optical receiver, the time difference between the IQ signals can be measured; the maintenance personnel can calculate the time difference in the DSP according to the time difference Set the time difference compensation value, which is compensated by DSP;

Here, the first signal and the second signal after the traditional time difference compensation can be obtained, wherein the first signal and the second signal are the I signal and the Q signal of the same polarization plane respectively; obtain the first signal and the second signal through a bypass line or the like;

After acquiring the first signal and the second signal, interpolation processing can be performed on the second signal, that is, the Q signal; data processing can be performed by the arithmetic unit in the DSP; it is assumed that the function of the Q signal is Q(t), where t is a time variable. First, the Q(t) data can be forward-interpolated to obtain the forward-interpolated data of the second signal Q _pre =Q(t-dt), and then the input Q(t) data can be backward-interpolated. Interpolate to obtain backward interpolation data of the second signal to obtain Q _pst =Q(t+dt).

Further, the difference step size dt may take a fixed value smaller than the ADC sampling period Ts, generally Ts/3.

In practical applications, methods such as Lagrangian interpolation method may be used to perform the interpolation calculation of the second signal.

The second determining module 52 is configured to respectively determine the first correlation between the first signal and the second signal, the second correlation between the difference value of the first signal and the difference value of the second signal, the The third correlation between the difference value of the first signal and the difference value of the result of forward interpolation of the second signal, and the fourth correlation between the difference value of the first signal and the difference value of the result of backward interpolation of the second signal Correlation;

Here, data processing can be performed by the arithmetic unit in the DSP; the first signal is an I signal, and the second signal is a Q signal; the first correlation λ between the I signal and the Q signal can be calculated; after calculating the difference between the I signal and the Q signal The second _{correlation γ after} the difference of γ _p st; wherein, the difference can be in the form of the expression f'(n)=f(n+1)-f(n), where f'(n) represents the next signal data f(n+1) Difference from the previous signal data f(n).

Further, it is generally considered that the differential operation is a simplified high-pass filter; the correlation between the I signal after passing through the low-pass filter and the Q signal after passing through the low-pass filter can be determined as the first correlation λ; The correlation between the Q signal after the high-pass filter and the Q signal after the high-pass filter is determined as the second correlation γ; the correlation between the I signal after the high-pass filter and the forward interpolation result of the Q signal after the high-pass filter is passed through the high-pass filter γ _pre , It is determined as the third correlation; the correlation between the I signal after passing through the high-pass filter and the backward interpolation result of the Q signal after passing through the high-pass filter is determined as the fourth correlation γ _pst ; the existing time difference measurement usually requires a higher The high-pass filter and the low-pass filter can improve the adaptability to the frequency offset, even if the frequency offset is small, high measurement accuracy can be obtained; the high-pass filter described here Common structures, such as 2 or 3-tap FIR filters, can be used for the filter and low-pass filter.

Further, the correlation value of the preset accumulation times N can be accumulated, and the average value is taken as the final correlation value; the I signal of the preset accumulation times N is subjected to a low-pass filter and the second signal is subjected to a low-pass filter. The average value of the correlation after the filter is determined as the first correlation λ; the average value of the correlation between the I signal after the high-pass filter and the Q signal after the high-pass filter for the preset accumulation times N is determined as the first Two correlations γ; the I signal of the preset accumulation times N is passed through the high-pass filter and the Q signal forward interpolation result is passed through the high-pass filter. The average value of the correlation is determined as the third correlation γ _pre ; the preset accumulation The average value of the correlation between the I signal of the number N and the backward interpolation result of the Q signal after the high-pass filter is passed through the high-pass filter, and is determined as the fourth correlation γ _pst ; wherein the selected preset accumulation number N is to adapt to the IQ time difference Since the device characteristics change very slowly, as long as a set of results can be output every 0.1s, it can keep up with the change of IQ time difference, so a larger N value, such as 2 ¹⁴ , can be selected to improve the average effect.

The adjustment module 53 is configured to, according to the first difference between the second correlation and the first correlation, and/or the second difference between the third correlation and the first correlation, and/or the fourth correlation and For the third difference value of the first correlation, the time difference compensation value is adjusted according to a preset adjustment rule; the time difference compensation value is used to adjust the time difference between the first signal and the second signal;

Here, the first difference δ between the second correlation γ and the first correlation λ, the second difference δ _pre between the third correlation γ _pre and the first correlation λ, and the fourth correlation γ _pst may be determined first. The third difference δ _pst with the first correlation λ; the first correlation λ can be subtracted from the second correlation γ to obtain the first difference δ; the first correlation λ is subtracted from the third correlation γ _pre , obtain the second difference δ _pre ; subtract the first correlation λ from the fourth correlation γ _pst to obtain the third difference δ _pst ;

The preset adjustment rule may be to adjust the time difference compensation value according to the comparison result of the first difference, the second difference and the third difference and a preset threshold; the first difference, the second difference The comparison result between the difference value and the third difference value and the threshold value reflects the time difference between the first signal and the second signal, so the time difference compensation value can be adjusted according to the comparison result. The adjusting the time difference compensation value according to the preset adjustment rule includes: when the first difference δ is greater than the first preset threshold, the second difference δ _pre is greater than the second preset threshold, and the third difference δ _pst is less than the first When there are two preset thresholds, the current time difference compensation value is increased; when the first difference δ is greater than the first preset threshold, the second difference δ _pre is smaller than the second preset threshold, and the third difference δ _pst is greater than the second preset When the threshold is set, reduce the current time difference compensation value;

Wherein, the first preset threshold and the second preset threshold may be determined through experimental data, wherein the first preset threshold may be 5/10000, the second preset threshold may be 3/1000, the The step size of the time difference compensation adjustment can be 1/512 of the ADC sampling period;

Here, since the first correlation is the first correlation between the I signal after passing through the low-pass filter and the Q signal after passing through the low-pass filter as the comparison base; in this way, compared with the existing comparison base of 0, it is possible to improve the For the tolerance of signal phase difference, the time difference compensation method provided by the embodiment of the present invention may be used before phase difference compensation.

In this way, the adjustment of the time difference compensation value is completed, and the time difference compensation is performed on the first signal and the second signal according to the time difference compensation value; and the time difference between the first signal and the second signal is continuously adjusted by this real-time feedback method; thereby improving the The synchronization of the first signal and the second signal is achieved.

In practical applications, the first determination module 51, the second determination module 52 and the adjustment module 53 can all be composed of a central processing unit (CPU), a microprocessor (MPU), a digital signal processor (DSP) in the optical receiver ), or Field Programmable Gate Array (FPGA) etc.

The above is only the best embodiment of the present invention, and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the within the protection scope of the present invention.

Claims (12)

1. A time difference compensation adjustment method, the method comprising:

acquiring a first signal and a second signal, and determining a forward interpolation result and a backward interpolation result of the second signal;

determining a first correlation of a first signal and a second signal, a second correlation of a differential value of the first signal and a differential value of the second signal, a third correlation of a differential value of the first signal and a differential value of a forward interpolation result of the second signal, and a fourth correlation of a differential value of the first signal and a differential value of a backward interpolation result of the second signal, respectively;

adjusting the time difference compensation value according to a preset adjustment rule and a first difference value of the second correlation and the first correlation, and/or a second difference value of the third correlation and the first correlation, and/or a third difference value of the fourth correlation and the first correlation; the time difference compensation value is used for adjusting the time difference of the first signal and the second signal.

2. The method of claim 1, wherein the determining a first correlation of a first signal and a second signal, a second correlation of a differential value of the first signal and a differential value of the second signal, a third correlation of the differential value of the first signal and a differential value of a forward interpolation result of the second signal, and a fourth correlation of the differential value of the first signal and a differential value of a backward interpolation result of the second signal, respectively, comprises:

determining the correlation between the first signal after passing through a low-pass filter and the second signal after passing through the low-pass filter as a first correlation;

determining the correlation between the first signal after passing through a high-pass filter and the second signal after passing through the high-pass filter as a second correlation;

after the first signal passes through a high-pass filter, the first signal and the second signal are subjected to correlation after a forward interpolation result passes through the high-pass filter, and the first signal and the second signal are determined to be third correlation;

and determining the correlation between the first signal after passing through a high-pass filter and the backward interpolation result of the second signal after passing through the high-pass filter as a fourth correlation.

3. The method of claim 1, wherein the determining a first correlation of a first signal and a second signal, a second correlation of a differential value of the first signal and a differential value of the second signal, a third correlation of the differential value of the first signal and a differential value of a forward interpolation result of the second signal, and a fourth correlation of the differential value of the first signal and a differential value of a backward interpolation result of the second signal, respectively, comprises:

determining the average value of the correlation of the first signal after passing through the low-pass filter and the second signal after passing through the low-pass filter for the preset accumulation times as a first correlation;

determining the average value of the correlation between the first signal with preset accumulation times after passing through a high-pass filter and the second signal after passing through the high-pass filter as a second correlation;

determining the average value of the correlation between the first signal with preset accumulation times after passing through a high-pass filter and the second signal forward interpolation result after passing through the high-pass filter as a third correlation;

and determining the average value of the correlation between the first signal with preset accumulation times after passing through a high-pass filter and the backward interpolation result of the second signal after passing through the high-pass filter as a fourth correlation.

4. The method according to any one of claims 1 to 3, wherein the adjusting the moveout compensation value according to a preset adjustment rule comprises:

when the first difference value is larger than a first preset threshold value, the second difference value is larger than a second preset threshold value, and the third difference value is smaller than the second preset threshold value, increasing a current time difference compensation value;

and when the first difference value is greater than a first preset threshold value, the second difference value is less than a second preset threshold value, and the third difference value is greater than the second preset threshold value, reducing the current time difference compensation value.

5. The method of any of claims 1 to 3, wherein determining the forward interpolation result and the backward interpolation result for the second signal comprises:

and taking a time interval smaller than the sampling period of the analog-to-digital conversion ADC to which the second signal belongs as an interpolation step length, and performing forward interpolation processing and backward interpolation processing on the second signal.

6. A method according to any one of claims 1 to 3, wherein the first and second signals are in-phase and quadrature signals, respectively, of the same plane of polarization.

7. A time difference compensation apparatus, characterized in that the apparatus comprises: the device comprises a first determining module, a second determining module and an adjusting module; wherein,

the first determining module is configured to obtain a first signal and a second signal, and determine a forward interpolation result and a backward interpolation result of the second signal;

the second determining module is configured to determine a first correlation between a first signal and a second signal, a second correlation between a differential value of the first signal and a differential value of the second signal, a third correlation between the differential value of the first signal and a differential value of a forward interpolation result of the second signal, and a fourth correlation between the differential value of the first signal and a differential value of a backward interpolation result of the second signal, respectively;

the adjusting module is used for adjusting the time difference compensation value according to a preset adjusting rule and a first difference value between the second correlation and the first correlation, and/or a second difference value between the third correlation and the first correlation, and/or a third difference value between the fourth correlation and the first correlation; the time difference compensation value is used for adjusting the time difference of the first signal and the second signal.

8. The apparatus of claim 7, wherein the second determining module is specifically configured to:

determining the correlation between the first signal after passing through a low-pass filter and the second signal after passing through the low-pass filter as a first correlation;

determining the correlation between the first signal after passing through a high-pass filter and the second signal after passing through the high-pass filter as a second correlation;

after the first signal passes through a high-pass filter, the first signal and the second signal are subjected to correlation after a forward interpolation result passes through the high-pass filter, and the first signal and the second signal are determined to be third correlation;

and determining the correlation between the first signal after passing through a high-pass filter and the backward interpolation result of the second signal after passing through the high-pass filter as a fourth correlation.

9. The apparatus of claim 7, wherein the second determining module is specifically configured to: determining the average value of the correlation of the first signal after passing through the low-pass filter and the second signal after passing through the low-pass filter for the preset accumulation times as a first correlation;

determining the average value of the correlation between the first signal with preset accumulation times after passing through a high-pass filter and the second signal after passing through the high-pass filter as a second correlation;

determining the average value of the correlation between the first signal with preset accumulation times after passing through a high-pass filter and the second signal forward interpolation result after passing through the high-pass filter as a third correlation;

and determining the average value of the correlation between the first signal with preset accumulation times after passing through a high-pass filter and the backward interpolation result of the second signal after passing through the high-pass filter as a fourth correlation.

10. The apparatus according to any one of claims 7 to 9, wherein the adjustment module is specifically configured to:

when the first difference value is larger than a first preset threshold value, the second difference value is larger than a second preset threshold value, and the third difference value is smaller than the second preset threshold value, increasing a current time difference compensation value;

and when the first difference value is greater than a first preset threshold value, the second difference value is less than a second preset threshold value, and the third difference value is greater than the second preset threshold value, reducing the current time difference compensation value.

11. The apparatus according to any one of claims 7 to 9, wherein the first determining module is specifically configured to:

and taking a time interval smaller than the sampling period of the analog-to-digital conversion ADC to which the second signal belongs as an interpolation step length, and performing forward interpolation processing and backward interpolation processing on the second signal.

12. The apparatus of any one of claims 7 to 9, wherein the first and second signals are in-phase and quadrature signals, respectively, of the same plane of polarization.

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