Biological Signal Processing Using Auto-Correlated Carrier Sequences
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Solution Overview
Problem
Biological signals are difficult to record non-invasively due to low amplitude relative to ambient noise, and conventional noise reduction methods like electrical shielding and filtering are not feasible in real-world applications where noise sources overlap with biological signal spectrums.
Innovation Solution
A computer-implemented method and system using highly auto-correlated carrier sequence codes (HACS) to transmit energy waves, modulate and demodulate biological signals, and filter noise artifacts based on peak to sideband ratios, effectively isolating true biological signals from noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional filtering techniques are used to reduce noise, then noise reduction is achieved, but the biological signal cannot be effectively separated because noise power spectrums overlap with biological signal power spectrums
Solution Approach 1:
The patent employs periodic modulation of the biological signal using a carrier wave, transforming the signal into a time-varying modulated signal. This periodic action allows the signal to be distinguished from noise through synchronous detection, as the modulated signal contains frequency components that do not overlap with the noise spectrum, enabling effective separation despite spectral overlap in the original signal
Solution Approach 2:
The patent introduces a carrier wave as an intermediary element that modulates the biological signal. This carrier wave acts as a mediator that shifts the signal to a different frequency domain where it can be separated from noise. The carrier wave carries the signal information through the noisy environment and enables recovery through demodulation, effectively bridging the gap between signal transmission and noise rejection
2Object-affected harmful factors
If electrical shielding and vibrational isolation are used to minimize noise impact, then noise reduction is achieved, but these control measures are not feasible in real world applications
Solution Approach 1:
The patent replaces mechanical and electrical isolation methods with a signal processing approach. Instead of using complex physical shielding and isolation mechanisms, the invention uses mathematical modulation and demodulation techniques to reject noise. This substitution transforms a mechanical/electrical problem into an information processing problem, dramatically reducing system complexity while maintaining noise rejection capability
Solution Approach 2:
The patent changes the frequency domain parameters of the biological signal by modulating it with a carrier wave. This parameter transformation shifts the signal from a low-frequency band where it overlaps with noise to a higher frequency band where it can be easily separated. The modulation process alters the signal's spectral characteristics, enabling simple filtering and noise rejection without complex physical measures
3Measurement precision
If the biological signal is transmitted with high amplitude to overcome noise, then signal detection is improved, but the low amplitude of biological signals relative to ambient noise cannot be changed
Solution Approach 1:
The patent uses periodic modulation to encode the weak biological signal onto a carrier wave. This periodic action concentrates the signal energy into specific frequency components during demodulation, effectively amplifying the signal relative to noise. The synchronous detection process exploits the periodic nature of the modulation to coherently integrate signal energy while rejecting non-synchronous noise, improving signal-to-noise ratio without increasing original signal amplitude
Solution Approach 2:
The patent applies preliminary modulation to the biological signal before it encounters the noisy transmission channel. By pre-modulating the signal with a carrier wave, the system prepares the signal for robust transmission through noise. This preliminary action embeds timing and frequency references into the signal, enabling subsequent synchronous detection that can reject noise even when the original signal amplitude remains low
Data Source
AI summary
A computer-implemented method including, transmitting a high-spectrum energy wave towards a subject from a first sensor and transmitting a low-spectrum energy wave towards the subject from a second sensor. In response, modulation with a carrier sequence code results in a modulated evoked biological signal. The carrier sequence code has an autocorrelation function. The method includes demodulating the modulated evoked biological signal by calculating a convolution of the modulated evoked biological signal with the carrier sequence code resulting in an evoked biological signal spectrum. The evoked biological signal spectrum has a peak to sideband ratio as a function of the carrier sequence code. The method includes calculating deviations between each element of the sampled evoked biological signal and the peak to sideband ratio and filtering noise artifacts from the sampled evoked biological signal based on the deviations.