Ingress Cancellation Tachometer for DOCSIS Demodulation
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Solution Overview
Problem
Narrow band ingress noise degrades demodulation fidelity in DOCSIS systems by causing high symbol/bit errors, making it impractical to avoid frequencies with such noise in modern high bandwidth networks.
Innovation Solution
A demodulator system that includes an ingress exciser and predictor to detect and remove narrowband ingress noise by converting RF signals to baseband, using FFT for frequency domain analysis, and applying thresholds to cancel interfering frequencies, with a filter and recovery network for robust demodulation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If narrow band ingress noise is present in the frequency spectrum, then the available frequency bands for communication are reduced, but avoiding these frequencies results in loss of bandwidth and reduced network capacity
Solution Approach 1:
The patent extracts and removes narrowband ingress noise from the received signal by identifying frequency bins with excessive power levels and subtracting their contribution from adjacent bins. This extraction process eliminates the harmful interference while preserving the useful signal bandwidth for DOCSIS communication.
Solution Approach 2:
The patent applies preliminary anti-action by detecting and canceling ingress noise before it degrades the demodulation process. The system proactively identifies frequency bins exceeding threshold power levels and preemptively removes their interference from the signal, preventing symbol errors before they occur.
2Object-affected harmful factors
If frequency bins with high power levels are identified and canceled, then ingress noise is reduced, but adjacent frequency bins may be incorrectly affected causing signal distortion
Solution Approach 1:
The patent applies local quality by treating each frequency bin individually based on its specific characteristics. The system identifies only those bins exceeding the threshold power level and applies cancellation selectively to those specific bins and their immediate neighbors, rather than applying uniform processing across the entire spectrum. This localized approach preserves signal integrity in unaffected regions.
Solution Approach 2:
The patent uses partial action by canceling only the excessive power contribution from identified ingress bins and a limited number of adjacent bins, rather than removing entire frequency channels. This partial cancellation approach removes just enough interference to eliminate ingress noise while preserving the majority of the useful signal content.
3Measurement precision
If a threshold power level is set for identifying ingress frequency bins, then detection accuracy improves, but the threshold setting becomes complex and requires careful tuning
Solution Approach 1:
The patent changes the parameter of threshold power level from a fixed value to a dynamically adjustable parameter that can be tuned based on specific network conditions. The system allows the threshold to be modified to accommodate different ingress scenarios, enabling optimization of detection accuracy for various operational environments without requiring complete system redesign.
Data Source
AI summary
Indication of an amount of processing performed in detection and removal of ingress noise may be provided. A frequency domain representation of a narrowband region of a digital input signal may be received. The received frequency domain representation of the narrowband region may be compared with a predetermined threshold. Results from the comparison of the received frequency domain representation of the narrowband region with the predetermined threshold may be aggregated. Based on the aggregated results, an indication of an amount of processing performed by an ingress exciser in removing the ingress noise may be provided.