Chromatic Dispersion Compensator Anti-Aliasing Filter
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Solution Overview
Problem
Existing digital signal processing (DSP) systems for coherent optical communication signals face high power consumption due to high sampling rates, which introduces aliasing noise when reduced below the Nyquist limit, and require costly or difficult-to-manufacture anti-aliasing filters.
Innovation Solution
A chromatic dispersion compensator with an integrated anti-aliasing filter transforms digital signal samples into the frequency domain, zeros out aliasing frequencies, and resamples at a lower rate, eliminating aliasing noise without the need for external filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the sampling rate of ADC is reduced to lower power consumption, then power consumption is reduced, but aliasing noise is introduced
Solution Approach 1:
The patent applies preliminary action by implementing anti-aliasing filtering in the frequency domain before the resampling operation. The chromatic dispersion compensator transforms the signal to the frequency domain, applies a filter to remove aliasing components, and then performs resampling at the lower rate. This preliminary filtering action prevents aliasing noise from being introduced during the rate reduction process.
Solution Approach 2:
The patent uses an intermediary approach by introducing a frequency domain filtering stage as a mediator between the high-rate sampling and the lower-rate resampling. This intermediary filtering step eliminates the harmful aliasing effects that would otherwise be introduced by direct rate reduction, allowing the system to operate at lower power consumption rates without performance degradation.
2Object-generated harmful factors
If anti-aliasing filters are added to prevent aliasing noise, then aliasing noise is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies merging by combining the anti-aliasing filtering function with the chromatic dispersion compensation function in a single integrated block. Instead of using separate external filters, the frequency domain filtering is implemented within the existing DSP pipeline of the chromatic dispersion compensator, reducing overall device complexity while maintaining effective aliasing suppression.
Solution Approach 2:
The patent substitutes the traditional mechanical/analog anti-aliasing filters with a digital frequency domain filtering approach. By transforming the signal to the frequency domain and applying digital filtering, the system replaces complex analog filter hardware with computationally efficient digital processing, reducing device complexity and manufacturing cost while maintaining filter performance.
3Use of energy by moving object
If sampling rate is reduced below Nyquist limit, then power consumption is reduced, but signal quality deteriorates
Solution Approach 1:
The patent applies preliminary action by performing frequency domain filtering before the resampling operation. This preliminary filtering removes aliasing components that would otherwise contaminate the signal when sampling at rates below the Nyquist limit, preserving signal quality even at reduced sampling rates.
Solution Approach 2:
The patent utilizes parameter changes by operating in the frequency domain rather than the time domain. By transforming the signal to the frequency domain, applying filtering, and then transforming back, the system changes the representation parameters to enable safe resampling below Nyquist rates while maintaining signal integrity through the filtering operation.
Data Source
AI summary
A chromatic dispersion compensator to receive a first set of digital signal values produced by sampling an analog signal at a first sampling rate and generate a second set of digital signal values by sampling the first set of digital signal values at a second sampling rate. The chromatic dispersion compensator applies a chromatic dispersion filter and an anti-aliasing filter to the first set of digital signal values.