Adaptive Decoding with PR Coefficient Updates for Stable Convergence
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Solution Overview
Problem
Existing decoding systems face challenges in maintaining convergence performance and operational stability as constraint lengths increase, particularly in high-density recording systems, where long constraint lengths lead to difficulties in proper convergence and stable operation.
Innovation Solution
A decoding device and method incorporating both adaptive equalization and adaptive maximum likelihood decoding, with a target waveform generation unit, error signal generation, and coefficient updating unit using least-square-method computation to minimize correlation between decoded values and error signals, allowing for optimal equalization target setting and reducing the need for identification points in adaptive equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the constraint length of PR is increased to address higher recording density, then the recording capacity is improved, but the number of identification points increases making convergence difficult and operation unstable
Solution Approach 1:
The patent changes the parameter of constraint length from small values (2-3) to large values (10 or greater) to increase recording capacity. This parameter change enables higher density recording but creates the technical problem of increased identification points (288 points when constraint length=11) that makes convergence difficult and operation unstable.
2Quantity of substance
If the constraint length of PR is increased to address higher recording density, then the recording capacity is improved, but convergence to linear equalization target becomes difficult
Solution Approach 1:
The patent increases the constraint length parameter to achieve higher recording capacity, but this creates convergence precision problems. With constraint length=11, the system must handle 288 identification points, making it very difficult to converge properly to the linear equalization target expressed by 11 PR coefficients.
3Reliability
If both adaptive equalization circuit and adaptive Viterbi circuit are used, then decoding performance is improved, but the system complexity increases
Solution Approach 1:
The patent combines adaptive equalization and adaptive Viterbi decoding into a unified system. The adaptive equalization circuit uses PR coefficients updated through LMS computation, while the adaptive Viterbi circuit uses identification points controlled by the same adaptive mechanism, merging two separate adaptive systems into one coordinated structure.
Solution Approach 2:
The patent creates a universal adaptive decoding system that handles both equalization and Viterbi decoding functions. The system uses a common adaptive control mechanism that can operate with different constraint lengths, providing multi-functionality for both equalization and maximum likelihood decoding operations.
Data Source
AI summary
Deterioration of convergence performance or operational stability due to an increase in constraint length is suppressed when coefficients are updated, so that decoding performance is improved. A decoding device according to the present technology includes an adaptive equalization unit that performs adaptive equalization, an adaptive maximum likelihood decoding unit that causes an identification point of maximum likelihood decoding to adaptively follow a characteristic of an input signal, a target waveform generation unit that, by convoluting a partial response coefficient into a decoded value, generates an equalization target waveform of the adaptive equalization which is performed by the adaptive equalization unit, an error signal generation unit that generates, as an equalization error signal, an error signal between the equalization target waveform and an equalized signal, and a coefficient updating unit that, through least-square-method computation for minimizing a correlation between the decoded value and the equalization error signal, updates the partial response coefficient which is used by the target waveform generation unit to generate the equalization target waveform.