I/Q Channel Inversion Switching for Faster Demodulation Sync

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Solution Overview

Problem

Existing demodulation techniques require re-establishing synchronization when channel inversion occurs, leading to increased demodulation time compared to non-inverted channels.

Innovation Solution

Implementing a demodulation device with a channel inversion control unit that switches and synchronizes the I and Q channels at the downstream process, maintaining established frequency and clock synchronization, thereby avoiding the need for re-synchronization upon channel inversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If channel inversion is detected and channels are switched, then correct demodulation is achieved, but demodulation time increases due to re-establishing synchronization

Engineering Contradiction:
Improvedemodulation correctnessVSAvoiddemodulation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by detecting channel inversion before it causes demodulation errors, using correlation between known and received sequences to identify inversion early. This allows the system to switch channels proactively rather than reactively, maintaining synchronization without interruption and thus reducing demodulation time while ensuring correctness.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by continuously monitoring the correlation value between known sequences and received sequences, using this feedback to detect channel inversion and trigger channel switching. This closed-loop feedback mechanism ensures reliable demodulation by automatically correcting channel inversion while minimizing time loss through rapid detection and response.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If channel inversion detection is implemented, then demodulation accuracy improves, but system complexity increases

Engineering Contradiction:
Improveinversion detection accuracyVSAvoiddemodulation system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses an intermediary approach by introducing a correlation calculation mechanism that compares known sequences with received sequences. This intermediary correlation value serves as a simple yet effective indicator of channel inversion, achieving high detection accuracy without requiring complex inversion detection circuits or algorithms.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies parameter changes by monitoring the correlation value parameter between known and received sequences. When this parameter falls below a threshold, it indicates channel inversion. This simple parameter-based detection method achieves high accuracy while maintaining low system complexity, avoiding the need for sophisticated detection mechanisms.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2811703B1Demodulation device, demodulation method, and program
Publication Date: 2019.04.03 SATURN LICENSING LLC
  • EP2811703B1 patent drawingFigure 1
  • EP2811703B1 patent drawingFigure 2
  • EP2811703B1 patent drawingFigure 3

AI summary

The present technique relates to a demodulation device, a demodulation method and a program capable of realizing a demodulation process at a rate equivalent to a case where I and Q channel signals are not inverted, even when the I and Q channel signals are inverted. A frequency correction unit establishes synchronization of a frequency and clock based on a signal from a frequency synchronization unit. A channel inversion detection unit of a frame synchronization unit detects presence or absence of inversion of I and Q channel signals, and supplies, as a detection result, a channel inversion detection result to the channel inversion control unit. The channel inversion control unit switches the I and Q channel signals if the inversion has occurred, based on the channel inversion detection result. This technique can be applied to a demodulation device.