Variable Carrier Frequency Sensor Signal Demodulation
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Solution Overview
Problem
Existing amplitude modulation and Goertzel algorithm-based sensor signal processing systems are susceptible to perturbation frequencies, leading to unacceptable measurement errors, especially in safety-critical applications like automobile components.
Innovation Solution
Implementing a signal processing unit that uses a variable carrier frequency for modulation and calculates coefficients based on these frequencies for demodulation, reducing susceptibility to perturbation frequencies by modulating the signal across different frequencies and using pre-calculated or synchronized coefficients for demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amplitude modulation with a fixed carrier frequency is used, then the computing outlay is low and the Goertzel algorithm is efficient, but the system becomes susceptible to perturbation frequencies causing measurement errors
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed carrier frequency to a variable carrier frequency that changes over time. The modulation signal is modulated with carrier frequencies that vary according to a predetermined pattern, causing the spectral distribution of the modulated signal to spread across multiple frequencies. This dynamic approach prevents any single perturbation frequency from consistently interfering with the measurement, thereby improving reliability while maintaining computational efficiency through the adapted Goertzel algorithm.
2Reliability
If a variable carrier frequency is used to reduce susceptibility to perturbation frequencies, then measurement reliability improves, but the computing outlay increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the carrier frequencies and their corresponding Goertzel coefficients before the actual measurement process. The variable carrier frequencies and their associated coefficients are determined in advance based on the modulation signal characteristics. This pre-computation stores the necessary parameters for demodulation, allowing the system to handle variable frequencies without significantly increasing the real-time computing burden during signal processing.
Solution Approach 2:
The patent applies parameter changes by modifying the Goertzel algorithm to accommodate variable carrier frequencies. Instead of using a single fixed frequency coefficient, the system uses multiple coefficients corresponding to different carrier frequencies that vary over time. The algorithm parameters are adjusted to match the instantaneous carrier frequency, enabling accurate demodulation while managing computational complexity through efficient parameter adaptation rather than complete recalculation.
Data Source
AI summary
A method for processing a signal modulated with a variable carrier frequency includes calculating a coefficient for demodulation of the signal. The method also includes demodulating the signal by calculating discrete intermediate values utilizing the coefficient for a predefined maximum number of steps and calculating the signal with the aid of the intermediate values of the coefficient. The value of the coefficient is respectively calculated on the basis of carrier frequencies for each step.