Direct Equalizer Tap Determination Using Signal Cross-Correlation
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Solution Overview
Problem
High-speed digital signals are degraded by less-than-ideal transmission channels in communication systems, making it difficult for receivers to accurately differentiate between zeros and ones, particularly in communication test systems used to characterize electronic devices, and existing equalization methods require complex derivation of tap coefficients for linear feed-forward equalizers.
Innovation Solution
A direct determination equalizer system (DDES) that includes an equalizer, cross-correlator, and processor to directly determine equalizer-tap coefficients by cross-correlating channel output signals with ideal signals, producing a set of linear equations to solve for optimal tap values, thereby compensating for deterministic effects in transmission channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear feed-forward equalizer (LFE) is used to compensate for channel effects, then signal accuracy is improved, but the complexity of deriving tap coefficients increases
Solution Approach 1:
The patent replaces complex iterative algorithms and formal derivation methods with a direct determination approach using cross-correlation. The cross-correlator computes the correlation between received signals and known training sequences to directly obtain tap coefficients, eliminating the need for iterative convergence algorithms and simplifying the coefficient derivation process while maintaining signal accuracy
Solution Approach 2:
The system uses the transmitted training sequences themselves to determine the optimal tap coefficients. The cross-correlator exploits the known structure of training sequences to self-determine the channel impulse response and equalizer coefficients without requiring external calibration or complex mathematical derivation, making the system self-configuring
2Reliability
If iterative convergence algorithms are used to determine tap coefficients, then equalization performance is improved, but the computational time and complexity increase
Solution Approach 1:
The patent performs preliminary action by using known training sequences to pre-determine the tap coefficients before actual data transmission. The cross-correlator computes coefficients during the training phase, allowing the equalizer to be pre-configured with optimal coefficients, eliminating the need for time-consuming iterative algorithms during operational phases
Solution Approach 2:
The patent substitutes iterative convergence algorithms with a direct cross-correlation method. Instead of repeatedly adjusting coefficients to minimize error, the system directly computes coefficients by correlating received training sequences with transmitted sequences, dramatically reducing computational time while maintaining equalization performance
Data Source
AI summary
A direct determination equalizer system (“DDES”) for compensating for the deterministic effects of a transmission channel and a data source is disclosed. The DDES may include an equalizer having equalizer-tap coefficients, a cross-correlator configured to receive the first sampled signal and an ideal signal and in response produce a cross-correlated signal, and a processor in signal communication with the equalizer and the cross-correlator. The equalizer is configured to receive a first sampled signal and in response produce an equalized output data signal sequence and the processor is configured to determine the equalizer-tap coefficients from the cross-correlated signal.