Clock Tone Power Boosting for Timing Recovery
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Solution Overview
Problem
Conventional timing recovery algorithms in communication systems are sensitive to attenuation caused by narrowband filters, limiting baud rate and spectral efficiency, especially in high baud rate data transmission where power loss at clock tone frequencies can cause algorithm failure.
Innovation Solution
A digital signal processing apparatus and method that implements power boosting within two predetermined frequency bands centered around clock tone frequencies, compensating for attenuation and enabling reliable timing recovery convergence by boosting signal power around these frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the baud rate is kept low to maintain effective timing recovery, then timing recovery reliability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent changes the power distribution parameter of the signal by boosting power in specific frequency bands (centered at clock tone frequencies and their harmonics) while maintaining the overall signal power. This allows the signal to maintain sufficient high-frequency components for timing recovery even at higher baud rates, resolving the contradiction between timing recovery reliability and spectral efficiency
Solution Approach 2:
The patent applies non-uniform power distribution across the frequency spectrum by selectively boosting power in specific frequency bands (where P(f) > P_threshold) rather than uniformly across all frequencies. This local enhancement of power in critical frequency regions maintains timing recovery capability while allowing overall baud rate increases for improved spectral efficiency
2Productivity
If the baud rate is increased to improve spectral efficiency, then productivity is improved, but timing recovery reliability deteriorates due to power loss at clock tone frequencies
Solution Approach 1:
The patent applies power boosting in the frequency domain before signal transmission as a preliminary action. By pre-enhancing the power at clock tone frequencies and their harmonics in the transmitted signal, the system compensates for anticipated power loss during transmission and filtering, enabling reliable timing recovery at higher baud rates without compromising spectral efficiency
3Measurement precision
If narrowband filtering is applied to improve signal selectivity, then frequency selectivity is improved, but timing recovery reliability deteriorates due to attenuation of high frequency components
Solution Approach 1:
The patent applies preliminary anti-action by boosting power in frequency bands containing clock tone frequencies and their harmonics before transmission. This pre-compensation counteracts the attenuation effect of narrowband filtering that will occur during transmission, allowing the use of narrowband filters for improved frequency selectivity while maintaining timing recovery reliability through the pre-enhanced high frequency components
Data Source
AI summary
A digital signal processing apparatus and method is described for a transmitter of a communication link. The digital signal processing apparatus comprises a pre-compensation filter for boosting power of a signal to be transmitted within two predetermined frequency bands. One of the predetermined frequency bands is centered around a clock tone frequency of fbaud/2, and the other one of the predetermined frequency bands is centered around a clock tone frequency of −fbaud/2, fbaud being a baud rate of the transmitted signal.