Encoded Signal Demodulation for Modulation Index Ambiguity
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Solution Overview
Problem
Existing demodulation methods for devices using Continuous Phase Modulation (CPM) or Gauss Frequency Shift Keying (GFSK) with modulation index ambiguity result in low demodulation performance, particularly in devices like Bluetooth, due to uncertainty in modulation index values.
Innovation Solution
An encoded signal demodulation method that uses a rational number within the modulation index range as a first modulation index to determine states, and a second modulation index to calculate practical accumulated phases, allowing for error correction path metrics and survivor path determination to improve demodulation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If differential demodulation or matched filter bank demodulation is used for GFSK/CPM signals with ambiguous modulation index, then the demodulation can be performed, but the demodulation performance is low
Solution Approach 1:
The patent changes the parameter approach by using a rational number within the modulation index range as a first modulation index to determine states, and a second modulation index to calculate practical accumulated phases. This parameter separation allows the system to handle modulation index ambiguity while maintaining accurate demodulation performance.
Solution Approach 2:
The patent introduces an intermediary mechanism through error correction path metrics and survivor path determination. This intermediary process bridges the gap between the ambiguous modulation index and the required demodulation accuracy, enabling reliable signal recovery despite parameter uncertainty.
2Ease of operation
If a fixed modulation index is used for demodulation, then the demodulation process is simplified, but errors occur when the actual modulation index varies within a range
Solution Approach 1:
The patent applies dynamics by making the demodulation process adaptive to modulation index variations. Instead of using a single fixed modulation index, the system dynamically selects different modulation index values for different purposes (state determination vs. phase calculation), allowing it to adapt to the actual signal characteristics while maintaining operational simplicity.
Solution Approach 2:
The patent changes parameters by using two different modulation index values: a rational number for state determination and another value for practical accumulated phase calculation. This parameter differentiation resolves the contradiction between simplicity and accuracy by optimizing each parameter for its specific function.
3Use of energy by moving object
If analog devices are used to achieve low-power characteristics in Bluetooth, then power consumption is reduced, but the modulation index becomes uncertain and falls within a range
Solution Approach 1:
The patent addresses the modulation index uncertainty caused by analog devices by changing the parameter approach. It uses a rational number within the modulation index range for state determination and another modulation index value for phase calculation, transforming the uncertainty into a manageable parameter variation that maintains demodulation accuracy while preserving low-power characteristics.
Solution Approach 2:
The patent effectively uses computationally efficient methods that can be implemented in resource-constrained analog devices. By using rational numbers and simplified phase calculations, the system achieves accurate demodulation without requiring high-precision analog components, thus maintaining low-power operation.
Data Source
AI summary
The present disclosure relates to an encoded signal demodulation method, apparatus, and device. Some embodiments of the present disclosure are beneficial to improving demodulation performance.