Digital Radio Receiver Frame Sync Using Preamble Error Comparison
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Solution Overview
Problem
Existing digital radio receivers face challenges in accurately synchronizing to incoming data packets due to noise and interference, leading to incorrect frame synchronization and increased power consumption, as setting the frame synchronization threshold improperly can reduce noise tolerance or cause decoding errors.
Innovation Solution
A method and receiver that compare a selected portion of the incoming symbol sequence not only to a predetermined symbol sequence but also to a set of symbol sequences formed by prepending different lengths of the preamble to the beginning of the predetermined sequence, determining a minimum error, and using a difference metric like Hamming distance to ensure correct frame synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the frame synchronization threshold is set low to improve noise tolerance, then the receiver can operate at lower signal-to-noise ratios, but the risk of incorrect frame synchronization increases
Solution Approach 1:
The patent segments the error detection process into two distinct stages: first comparing the received symbol sequence against the expected access address, and second comparing against potential preamble misalignment sequences. This segmentation allows each comparison to have optimized threshold criteria, resolving the contradiction between noise tolerance and synchronization accuracy.
Solution Approach 2:
The patent introduces an intermediary comparison mechanism that evaluates multiple candidate sequences (including preamble variations) before committing to frame synchronization. This intermediary step acts as a buffer that prevents premature synchronization decisions, allowing the system to maintain lower thresholds while avoiding false positives through additional verification.
2Measurement precision
If the frame synchronization threshold is set high to avoid incorrect synchronization, then frame synchronization accuracy improves, but noise tolerance decreases
Solution Approach 1:
By dividing the synchronization verification into separate comparison stages (access address match followed by preamble alignment check), the system can apply stricter criteria at each stage rather than one high threshold, achieving both accuracy and noise tolerance.
Solution Approach 2:
The patent performs preliminary comparison against the access address before attempting frame synchronization. This preliminary action filters out clearly incorrect sequences early, allowing the system to use higher confidence thresholds for the final synchronization decision without losing legitimate weak signals.
3Measurement precision
If every possible symbol sequence is decoded during frame synchronization, then synchronization accuracy improves, but power consumption increases
Solution Approach 1:
The patent extracts and compares only the critical portions of the received sequence (access address and preamble sections) against expected patterns before committing to full decoding. This extraction approach identifies likely candidates without performing exhaustive decoding of every possible sequence, dramatically reducing power consumption while maintaining accuracy.
Solution Approach 2:
Instead of performing complete decoding on every candidate sequence, the patent applies partial action by conducting lightweight comparison operations first. Only sequences that pass these preliminary checks undergo full decoding, eliminating the need for exhaustive processing while preserving synchronization accuracy.
4Reliability
If the receiver attempts to decode sequences with high error rates, then noise tolerance improves, but decoding errors increase
Solution Approach 1:
The patent performs preliminary error assessment by comparing received sequences against expected patterns before attempting decoding. Sequences showing excessive deviation during this preliminary stage are rejected upfront, preventing wasted decoding attempts on hopeless candidates while preserving the ability to decode marginally degraded valid sequences.
Solution Approach 2:
The comparison mechanism provides feedback about sequence quality before decoding is attempted. This feedback loop allows the system to adjust its decoding strategy based on the apparent quality of received sequences, avoiding decoding attempts on severely corrupted data while maintaining robustness for borderline cases.
Data Source
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AI summary
A method of operating a digital radio receiver (2) is provided. The method comprises: a) receiving an incoming radio signal comprising an incoming symbol sequence (102); b) selecting a portion of the incoming symbol sequence (102); c) determining a first error between the selected portion of the incoming symbol sequence (102) and a first predetermined symbol sequence (11) using a difference metric; d) determining, using the difference metric, a set of second errors between the selected portion of the incoming symbol sequence (102) and a respective set of second predetermined symbol sequences (13), each formed by prepending different length portions of a predetermined preamble symbol sequence (104) to a beginning of the first predetermined symbol sequence (11); and e) determining a minimum error from the first error and the set of second errors. If the first error is not the minimum error, a different portion of the incoming symbol sequence (102) is selected and steps c) to e) are repeated. If the first error is the minimum error, a following portion of the incoming symbol sequence (102) is decoded to produce a data payload.