Cable CFR Tilt Equalization to Prevent Peak Regrowth
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Solution Overview
Problem
Cable communication systems face challenges in integrating Crest Factor Reduction (CFR) techniques from wireless communication systems due to incompatibility with tilt compensation components, leading to peak regrowth issues and unrecoverable distortion in power amplifiers.
Innovation Solution
The implementation of a tilt-adjusted CFR approach, which includes a tilt reference circuit and a tilt equalizer, allows CFR to be used effectively in cable communication systems by compensating for frequency-dependent signal losses and preventing peak regrowth, using a combination of digital and analog frequency modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If CFR techniques are integrated into cable communication systems, then peak power clipping is reduced, but peak regrowth occurs due to tilt compensation incompatibility
Solution Approach 1:
The patent applies preliminary action by performing CFR processing before tilt compensation in the signal chain. The CFR circuit reduces peak power clipping upfront, and then the tilt compensation circuit adjusts frequency balance without causing peak regrowth, because the peak reduction has already been established in the preliminary stage.
Solution Approach 2:
The patent segments the signal processing into distinct functional blocks: a CFR processing stage and a tilt compensation stage. This segmentation allows each circuit to perform its specific function independently, preventing the interaction that causes peak regrowth when these functions are combined in incompatible ways.
2Reliability
If tilt compensation is applied to compensate for frequency-dependent signal losses, then signal quality is improved, but it causes peak regrowth when CFR is used
Solution Approach 1:
The patent establishes the correct signal processing sequence where CFR is applied preliminarily before tilt compensation. This preliminary peak reduction ensures that subsequent tilt compensation operations do not regenerate peaks, thereby maintaining signal quality without the harmful side effect of peak regrowth.
Solution Approach 2:
The patent changes the operational parameters of the tilt compensation circuit by adjusting its transfer function to work compatibly with CFR-processed signals. This parameter adjustment ensures that the tilt compensation improves signal quality while operating within the constraints established by the prior CFR processing.
3Object-affected harmful factors
If standard CFR is implemented, then peak reduction is achieved, but unrecoverable distortion occurs in power amplifiers
Solution Approach 1:
The patent introduces tilt compensation as an intermediary circuit between the CFR processing and the power amplifier. This intermediary adjusts the frequency balance of the CFR-processed signal, ensuring that the peak reduction benefits are preserved while preventing the unrecoverable distortion that would otherwise occur in the power amplifier stage.
Data Source
AI summary
Otherwise incompatible crest factor reduction (CFR) and cable tilt compensation can be used together, such as in a cable television or other cable communication system having a frequency-dependent signal loss at higher frequencies. The CFR can be used to limit or reduce peaks of signals provided to a power amplifier, while additional tilt reference and tilt equalizer circuits are included to address deleterious peak regrowth effects that may otherwise arise by using conventional CFR together with cable tilt compensation.