Demodulation Device Using Complex Quotient for Transducer Signal Stability
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Solution Overview
Problem
Existing demodulation methods for transducers, such as magnetoelastic sensors, face challenges including sensitivity changes due to varying excitation amplitude and harmonic content, high demand on electronics for precise frequency response, and difficulty in deriving reference waveforms, leading to increased costs and complexity.
Innovation Solution
A method that computes complex valued quantities for both the output and excitation signals at the excitation frequency, forming a quotient to demodulate the signal independently of excitation amplitude and phase changes, allowing for the use of simpler electronics and eliminating the need for precise harmonic filtering and reference waveform derivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional analogue phase sensitive detection or digital sampling methods are used for demodulation, then the output stability can be maintained, but the system complexity and cost increase due to requirements for precise frequency response, reference waveform derivation, and harmonic filtering
Solution Approach 1:
The patent extracts and eliminates the complex components of traditional demodulation systems by using a different approach: instead of requiring precise reference waveforms, harmonic filtering, and frequency response control, the invention uses a simplified digital signal processing method that achieves stable output through alternative means, thereby removing the problematic elements while maintaining reliability
Solution Approach 2:
The patent replaces the complex analogue/digital hybrid demodulation system with a purely digital signal processing approach. By substituting the mechanical/electronic reference waveform generation and filtering systems with digital computation methods, the invention achieves the same stability function with reduced complexity and cost
2Measurement precision
If precise frequency response and reference waveform derivation are required for accurate demodulation, then measurement precision improves, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent employs inexpensive digital signal processing algorithms that can be implemented using low-cost electronics or even software. The method replaces expensive precision analogue components with computationally efficient digital techniques that achieve the same measurement precision at a fraction of the manufacturing cost
Solution Approach 2:
The invention changes the fundamental parameters of the demodulation approach by moving from analogue domain processing with strict frequency response requirements to digital domain processing where flexibility is achieved through computational algorithms rather than hardware precision, thereby reducing manufacturing costs while maintaining accuracy
3Measurement precision
If excitation amplitude is kept constant to maintain sensitivity, then measurement precision is maintained, but the system becomes more complex and costly due to additional control requirements
Solution Approach 1:
The patent incorporates feedback mechanisms in the digital signal processing domain, where the system continuously monitors and compensates for excitation amplitude variations through computational correction factors. This feedback approach maintains sensitivity stability without requiring complex external control systems, as the correction is applied algorithmically to the measured signal
Solution Approach 2:
The demodulation system performs self-correction by automatically compensating for excitation variations through internal digital processing. The system uses the measured signal itself to derive correction factors, eliminating the need for separate control systems and reducing overall complexity while maintaining measurement precision
Data Source
Figure 1~2
AI summary
The present invention relates to a method and a device for de- modulation of an output signal from a transducer (1) driven by an alternating excitation signal having an excitation frequency. Th e transducer produces an amplitude-modulated output signal (y(t)) containing the quantity to be measured. The device comprises sampling units (5,6,7) adapted to sample the output signal from the transducer and the output signal from the excitation unit, and a computation unit (8) adapted to compute a first complex valued quantity ( Y ) including information on the amplitude and phase of the output signal at the excitation frequency based on sampled values of the output signal from the transducer, compute a second complex valued quantity ( U , I ) including information on the amplitude and phase of the excitation signal at t h e excitation frequency based on sampled values of the excitation signal, forming a complex valued output quotient between said first and second complex valued quantities, and compute the demodulated output signal (O d ) based on said output quotient.