FSK Signal Discrimination Using Phase Difference Variance
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Solution Overview
Problem
Existing Bluetooth low energy (BLE) receiver technologies face challenges in accurately discriminating between Gaussian frequency shift keying (GFSK)-modulated signals and noise or continuous wave signals, with high error rates and power consumption due to complex correlation schemes.
Innovation Solution
A receiver that utilizes phase difference variance to discriminate between FSK-modulated signals, noise, and continuous wave signals, employing a filter chain, sampling circuit, CORDIC, differentiator, variance determination circuits, and an FSK discrimination circuit to set thresholds for accurate signal classification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pattern detection using correlators is used to detect GFSK-modulated signals, then detection capability is improved, but power consumption increases significantly and error rate increases
Solution Approach 1:
The patent extracts only the essential characteristic needed for GFSK detection - the phase relationship between consecutive samples - and uses this extracted feature (phase difference variance) for discrimination. This avoids the need for full correlation operations while retaining detection capability, thereby reducing power consumption significantly.
Solution Approach 2:
Instead of correlating the received signal with expected GFSK patterns (conventional approach), the patent inverts the approach by analyzing the statistical properties of phase differences in the received signal itself. This inversion leads to a simpler variance calculation that consumes less power while achieving reliable detection.
2Use of energy by moving object
If signal strength-based discrimination is used, then power consumption is reduced, but false alarm rate increases and miss detection rate increases
Solution Approach 1:
The patent changes the discrimination parameter from signal strength (amplitude) to phase difference variance. This parameter change enables the system to distinguish GFSK signals from interference more effectively, as phase relationships are characteristic of modulated signals regardless of amplitude, thereby improving detection accuracy while maintaining low power consumption.
3Measurement precision
If complex correlation schemes are used, then signal discrimination accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the phase difference component from the received signal and computes its variance, discarding unnecessary correlation operations. This extraction approach maintains discrimination accuracy by focusing on the essential characteristic (phase relationship) while dramatically simplifying the device complexity.
Solution Approach 2:
The patent replaces the mechanical correlation process with a statistical analysis of phase differences. Instead of performing complex correlation computations, the system computes the variance of phase differences, which is a simpler mathematical operation that achieves the same discrimination goal with reduced complexity.
Data Source
AI summary
A receiver, including: a sampling circuit configured to convert a received analog signal into a digital signal; a variance determination circuit configured to determine a phase difference variance of the digital signal; and a frequency shift keying (FSK) discrimination circuit configured to discriminate, based on the phase difference variance, whether the received analog signal is an FSK-modulated signal.