Method and system of synchronizing data to reference time signal with data resampling
View Patent ↗A device receives a data signal and a reference timing signal provided from a first clock. The device includes a sample clock that operates independently from the first clock, wherein the sample clock outputs a sample clock signal that is asynchronous with the reference timing signal; a sampler for sampling a data signal in accordance with the sample clock signal and outputting a sampled data signal; and a resampler for resampling the sampled data signal according to a resampling ratio and outputting a resampled data signal such that a number of data samples in the resampled data signal within a synchronization time interval defined with respect to the reference timing signal equals a nominal number of data samples that would occur in the sampled data signal within the synchronization time interval when the sample clock signal was synchronized to the reference timing signal.
1. A device, comprising:
an input configured to provide a reference timing signal generated from a first clock;
a sample clock that operates independently from the first clock, wherein the sample clock outputs a sample clock signal that is asynchronous with the reference timing signal;
a sampler configured to sample a data signal in accordance with the sample clock signal and outputting a sampled data signal;
a resampler configured to resample the sampled data signal according to a resampling ratio and outputting a resampled data signal such that a number of data samples in the resampled data signal within a synchronization time interval defined with respect to the reference timing signal equals a nominal number of data samples that would occur in the sampled data signal within the synchronization time interval when the sample clock signal was synchronized to the reference timing signal; and
a time stamper configured to periodically insert time stamps within the resampled data signal at fixed time intervals as measured with respect to the reference timing signal.
2. The device of claim 1 , wherein the reference timing signal is a coordinated universal time (UTC) signal.
3. The device of claim 1 , wherein the reference timing signal is Global Positioning System (GPS) timing signal.
4. The device of claim 1 , wherein the input receives the reference timing signal via an IEEE-1588 interface.
5. The device of claim 1 , wherein the sampler comprises an analog-to-digital converter (ADC).
6. The device of claim 1 , wherein the resampler applies a time shift to a plurality of data samples spread over the synchronization time interval to achieve a change in the resampling rate.
7. The device of claim 1 , wherein the resampler further resamples the sample clock signal and outputs a resampled sample clock signal.
8. The device of claim 7 , further comprising a controller configured to receive the reference timing signal and the resampled sample clock signal and in response thereto to generate the resampling ratio for each synchronization time interval and to provide the resampling ratio to the resampler.
9. The device of claim 1 , the fixed time interval is the synchronization time interval.
10. A method, comprising:
providing a reference timing signal;
generating a sample clock signal independent of, and asynchronous with, the reference timing signal;
receiving a data signal;
sampling the data signal in response to the sample clock signal to produce a sampled data signal;
setting a resampling ratio; and
resampling the sampled data signal according to the resampling ratio,
wherein the resampling ratio is updated once for each synchronization time interval such that a number of data samples in the resampled data signal within each synchronization time interval equals a nominal number of data samples that would occur in the sampled data signal within each synchronization time interval when the sample clock signal was synchronized to the reference timing signal, wherein the synchronization time interval is defined with respect to the reference timing signal.
11. The method of claim 10 , wherein the reference timing signal is a coordinated universal time (UTC) signal.
12. The method of claim 10 , wherein the reference timing signal is Global Positioning System (GPS) timing signal.
13. The method of claim 10 , wherein the reference timing signal is produced from an IEEE-1588 interface.
14. The method of claim 10 , wherein sampling the data signal comprises performing an analog-to-digital conversion of the data signal.
15. The method of claim 10 , wherein resampling includes applying a time shift to a plurality of data samples spread over the synchronization time interval to achieve a change in the resampling rate.
16. A method, comprising:
providing a reference timing signal according to a first clock;
outputting a sample clock signal that is asynchronous with the reference timing signal according to a sample clock that operates independently from the first clock;
sampling a data signal according to the sample clock signal and outputting a sampled data signal;
resampling the sampled data signal according to a resampling ratio;
outputting a resampled data signal such that a number of data samples within a synchronization time interval defined with respect to the reference timing signal equals a nominal number of data samples having an equivalent number of sample that would occur in the sampled data signal within the synchronization time interval when the sample clock signal was synchronized to the reference timing signal; and
periodically inserting time stamps within the resampled data signal at a fixed time interval as measured with respect to the reference timing signal.
17. The method of claim 16 , further comprising:
counting a number of resampled sample clock periods within the synchronization time interval;
comparing the counted number of resampled sample clock periods with a nominal number of resampled sample clock periods that would occur within the synchronization time interval when the sample clock signal was synchronized to the reference timing signal; and
updating the resampling ratio in response to the comparison.
18. The method of claim 16 , wherein the fixed time interval is the synchronization time interval.
19. A device, comprising:
an input configured to provide a reference timing signal generated from a first clock;
a sample clock that operates independently from the first clock, wherein the sample clock outputs a sample clock signal that is asynchronous with the reference timing signal;
a sampler configured to sample a data signal in accordance with the sample clock signal and outputting a sampled data signal; and
a resampler configured to resample the sampled data signal according to a resampling ratio and outputting a resampled data signal, wherein the resampling ratio is updated once for each synchronization time interval such that a number of data samples in the resampled data signal within a synchronization time interval defined with respect to the reference timing signal equals a nominal number of data samples that would occur in the sampled data signal within the synchronization time interval when the sample clock signal was synchronized to the reference timing signal.