Iterative DSC Decoding for Weak Distress Signal Reception

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Solution Overview

Problem

Current terrestrial DSC systems face limitations in receiving weaker distress signals, particularly beyond 20 nautical miles from the coastline, leading to coverage gaps and reduced effectiveness in maritime emergency responses.

Innovation Solution

An iterative decoding system utilizing zero-based parity and maximum a posteriori (MAP) decoding algorithms to enhance the reception of DSC messages, enabling the correction of errors and improving signal recognition, thereby facilitating the rescue of mariners in distress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional DSC reception methods are used, then the system can receive distress signals within 20 nautical miles of the coastline, but the receiver cannot reliably detect weaker signals beyond this range

Engineering Contradiction:
Improvedistress signal reception reliabilityVSAvoidcoverage area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The system performs preliminary error detection and correction by dividing the received signal into multiple blocks and applying iterative decoding algorithms before final signal reconstruction. This preliminary processing enhances the receiver's ability to detect and correct errors in weak signals, extending reliable reception beyond the traditional 20 nautical mile coverage limit.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The iterative decoding process incorporates feedback mechanisms where decoded blocks are used to improve subsequent decoding iterations. The system uses soft decision feedback and probability information from previous decoding attempts to enhance the detection of weak signals, thereby improving reliability in extended coverage areas.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If the receiver processes signals using traditional decoding, then the processing is simpler, but error detection and correction capability is insufficient for weak signals

Engineering Contradiction:
Improvesignal error detection precisionVSAvoiddecoding process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The received signal is segmented into multiple blocks for independent processing. Each block undergoes separate error detection and correction using iterative decoding algorithms. This segmentation allows the complex decoding process to be applied selectively to individual signal segments, improving overall error detection precision while managing computational complexity through modular processing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system applies iterative decoding with multiple passes and redundant error checking beyond what traditional single-pass decoding provides. This excessive action in error detection and correction processes enhances precision for weak signals, accepting increased computational complexity as necessary to achieve reliable reception of marginal signals.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS20220376821A1Iterative decoding technique system and method for digital selective calling
Publication Date: 2022.11.24 AEROSPACE CORP
  • US20220376821A1 patent drawing
  • US20220376821A1 patent drawing
  • US20220376821A1 patent drawing

AI summary

System and methods are disclosed that comprise receiving at least one signal via a receiver. The at least one signal is extracted for data via a processor coupled to the receiver, wherein the data includes at least one message and a set of parameters related to the message. A signal output is generated using the at least one message and the set of parameters such that the signal output includes a first portion and a second portion. At least one error is identified in the signal output and corrected using the first portion and the second portion. An output is generated that is used to perform at least one task related to the at least one signal.