Signal sampling method and apparatus, and optical receiver
The present disclosure provides a signal sampling method and apparatus, and an optical receiver. The method includes sampling a burst signal that is received according to a first sampling frequency to obtain a first sampling signal; sampling a preamble signal in the first sampling signal according to a second sampling frequency to obtain a second sampling signal; determining a phase difference between the burst signal and a local sampling clock corresponding to the first sampling frequency according to the second sampling signal; and interpolating the first sampling signal according to the phase difference to obtain a target sampling signal.
1. A signal sampling method, comprising:
sampling a burst signal according to a first sampling frequency to obtain a first sampling signal;
sampling a preamble signal in the first sampling signal according to a second sampling frequency to obtain a second sampling signal;
determining a phase difference between the burst signal and a local sampling clock corresponding to the first sampling frequency according to the second sampling signal; and
interpolating the first sampling signal according to the phase difference to obtain a target sampling signal;
wherein determining the phase difference between the burst signal and the local sampling clock corresponding to the first sampling frequency according to the second sampling signal comprises:
performing symbol decision on the second sampling signal to obtain a decision signal;
determining an error signal of the second sampling signal and the decision signal; and
determining the phase difference between the burst signal and the local sampling clock corresponding to the first sampling frequency according to the error signal.
2. The method according to claim 1 , wherein determining the phase difference between the burst signal and the local sampling clock corresponding to the first sampling frequency according to the error signal comprises:
determining a result of discrete Fourier transform of the error signal at a symbol frequency corresponding to the burst signal; and
determining the phase difference according to the result of the discrete Fourier transform.
3. The method according to claim 2 , wherein determining the phase difference according to the result of the discrete Fourier transform comprises:
extracting a sampling phase according to the result of the discrete Fourier transform, and determining the phase difference according to the sampling phase.
4. The method according to claim 1 , wherein determining the phase difference between the burst signal and the local sampling clock corresponding to the first sampling frequency according to the second sampling signal comprises:
cancelling inter-symbol interference of the second sampling signal; and
determining the phase difference between the burst signal and the local sampling clock corresponding to the first sampling frequency according to the second sampling signal in which the inter-symbol interference is cancelled.
5. The method according to claim 1 , wherein interpolating the first sampling signal according to the phase difference to obtain the target sampling signal comprises:
determining a sample point offset of the first sampling signal according to the phase difference; and
interpolating the first sampling signal according to the sample point offset to obtain the target sampling signal.
6. An optical line terminal, comprising:
a receiver, configured to receive and sample a burst signal according to a first sampling frequency to obtain a first sampling signal;
a 2-times up-sampler coupled to the receiver, configured to sample a preamble signal in the first sampling signal according to a second sampling frequency to obtain a second sampling signal; and
an interpolation filter, configured to interpolate the first sampling signal according to a phase difference to obtain a target sampling signal, wherein the phase difference is between the burst signal and a local sampling clock corresponding to the first sampling frequency and is determined according to the second sampling signal;
wherein the optical line terminal further comprises a processor configured to:
perform symbol decision on the second sampling signal to obtain a decision signal;
determine an error signal of the second sampling signal and the decision signal; and
determine the phase difference between the burst signal and the local sampling clock corresponding to the first sampling frequency according to the error signal.
7. The optical line terminal according to claim 6 , wherein the processor is further configured to:
determine a result of discrete Fourier transform of the error signal at a symbol frequency corresponding to the burst signal; and
determine the phase difference according to the result of the discrete Fourier transform.
8. The optical line terminal according to claim 7 , wherein the processor is configured to extract a sampling phase according to the result of the discrete Fourier transform, and determining the phase difference according to the sampling phase.
9. The optical line terminal according to claim 6 , wherein the optical line terminal further comprises an equalization filter configured to:
cancel inter-symbol interference of the second sampling signal;
wherein the phase difference between the burst signal and the local sampling clock corresponding to the first sampling frequency is determined according to the second sampling signal in which the inter-symbol interference is cancelled.
10. The optical line terminal according to claim 6 , wherein the interpolation filter is further configured to:
determine a sample point offset of the first sampling signal according to the phase difference; and
interpolate the first sampling signal according to the sample point offset to obtain the target sampling signal.