Adaptive Equalization Device Single Digital Filter
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Solution Overview
Problem
Conventional digital signal processing in coherent optical communication systems experiences signal degradation due to accumulated computation errors from sequential multiplication processes in frequency control, phase adjustment, and adaptive equalization, which increases circuit scale and power consumption.
Innovation Solution
An adaptive equalization device that combines phase difference compensation and adaptive equalization using a single FIR filter with combined filter coefficients, reducing the number of processes and circuit scale, and minimizing computation errors by performing these functions simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency control, phase adjustment, and adaptive equalization are sequentially executed in separate digital filters, then each process can be performed independently, but computation errors accumulate and signal degradation occurs
Solution Approach 1:
The patent merges frequency control, phase adjustment, and adaptive equalization into a single digital filter structure. The filter simultaneously performs all three functions by processing the received signal in one unified operation, eliminating the sequential execution that caused error accumulation. The filter coefficients are designed to accomplish multiple compensation tasks in parallel, directly resolving the contradiction between independent process execution and error accumulation.
2Adaptability or versatility
If multiple separate digital filters are used for frequency control, phase adjustment, and adaptive equalization, then each function can be optimized independently, but circuit scale increases
Solution Approach 1:
The patent creates a universal digital filter that performs multiple functions simultaneously. The single filter structure is designed with coefficients that enable it to execute frequency control, phase adjustment, and adaptive equalization all at once. This multi-functional approach maintains the optimization benefits of separate processes while consolidating them into one circuit, thereby reducing overall circuit scale while preserving functional versatility.
3Reliability
If multiple separate digital filters are used for frequency control, phase adjustment, and adaptive equalization, then each process can be performed with dedicated hardware, but power consumption increases
Solution Approach 1:
The patent combines multiple processing functions into a single digital filter operation, which reduces the total computational load. By performing frequency control, phase adjustment, and adaptive equalization in one unified filter pass rather than through multiple sequential filters, the system reduces the number of multiplication and addition operations required. This consolidation maintains processing accuracy while significantly reducing power consumption associated with digital signal processing operations.
Data Source
AI summary
First compensation circuitry includes a first digital filter compensating a phase difference between a phase of a symbol of a received signal and a sampling timing, and first filter coefficient calculation circuitry calculating a filter coefficient of the first digital filter as a first filter coefficient. Second filter coefficient calculation circuitry calculates, as a second filter coefficient, a filter coefficient for adaptive equalization that compensates distortion due to temporally changing polarization dispersion, based on an output of the first digital filter. Coefficient combination circuitry combines the first filter coefficient and the second filter coefficient. Second compensation circuitry includes a second digital filter which uses a filter coefficient combined by the coefficient combination circuitry and performs a compensation of the phase difference between the phase of the symbol of the received signal and the sampling timing, and a process of the adaptive equalization at the same time.