DSSS Digital Receiver Error Correction Block
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Solution Overview
Problem
In digital radio frequency communication, direct sequence spread spectrum (DSSS) decoding is hindered by noise and imperfect demodulation, leading to errors in recovered binary messages and synchronization clocks, causing significant performance degradation in matched filter-based decoding processes.
Innovation Solution
A device with an error correction block that stores and compares received binary samples against possible values to replace them with the closest stored sequence, minimizing errors, and applies the corrected sequence to a matched filter for decoding, utilizing a finite impulse response digital filter and hysterisis comparators with adjustable thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If matched filter-based decoding is used for DSSS signals, then decoding capability is provided, but noise and imperfect demodulation cause errors in recovered binary messages and synchronization clocks, leading to performance degradation
Solution Approach 1:
The patent applies preliminary action by performing error correction on binary samples before they are processed by the matched filter. The system stores corrected versions of binary samples in a memory buffer and replaces erroneous samples with corrected ones prior to decoding, thereby preventing error propagation through the decoding process and improving overall reliability
Solution Approach 2:
The patent implements feedback by using the output of the matched filter to identify errors in the binary samples, then feeding this error information back to correct the samples. The system continuously monitors decoding results and uses this information to improve subsequent decoding operations, creating a closed-loop error correction mechanism
2Reliability
If error correction is applied to binary samples before matched filter processing, then decoding performance is enhanced, but device complexity increases due to additional error correction block components
Solution Approach 1:
The patent applies copying by creating stored copies of corrected binary samples in a memory buffer. Instead of complex real-time error correction, the system captures corrected sample sequences and stores them for reuse, simplifying the error correction mechanism while maintaining high decoding accuracy through repeated use of verified sample data
Solution Approach 2:
The patent implements universality by designing the error correction block to handle multiple functions within a single integrated structure. The same correction mechanism serves both binary message decoding and synchronization clock recovery, reducing overall system complexity while improving both functions simultaneously
3Measurement precision
If binary samples are corrected by comparing with stored sequences, then error rate decreases, but processing time increases due to comparison operations
Solution Approach 1:
The patent applies preliminary action by pre-storing valid binary sample sequences in a memory buffer before they are needed for correction. This allows the error correction process to simply compare and select from pre-validated options rather than performing complex real-time analysis, significantly reducing processing time while maintaining high accuracy
Solution Approach 2:
The patent uses simple comparison logic and stored reference sequences instead of complex error correction algorithms. The correction mechanism relies on basic sequence matching and selection from pre-stored valid patterns, providing an computationally efficient solution that minimizes processing time while achieving accurate error correction
Data Source
AI summary
A device for decoding a direct sequence spread spectrum-encoded binary message includes a sampler that captures at least one sequence of binary samples corresponding to one bit of the transmitted message. The captured sequence of samples are applied to a filter matched to the spreading code used, thus making it possible to delete the spreading applied to the original message. The device further includes, at the output of the sampler, an error correction block including a memory storing a plurality of binary sequences corresponding to all of the possible values for a captured sequence of samples. A replacement circuit replaces the captured sequence of samples with the stored sequence, thereby minimizing the number of samples different from the captured sequence of samples, and allowing the stored sequence to be applied to the matched filter.