Sub-Nyquist Signal Acquisition System for Power Reduction
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Solution Overview
Problem
Traditional signal acquisition methods require sampling rates above the Nyquist rate, leading to high power consumption, low resolution, and increased size and weight, particularly in battery-powered systems, and additional processing is needed for data compression.
Innovation Solution
A sensing and recovery system that generates a bandlimited continuous time analog signal, modulates it at a rate equal to or greater than the Nyquist rate, and uses a compressive sensing circuit to sample at a rate less than the Nyquist rate, avoiding transform coding and reducing processing steps, thereby saving power, size, and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data compression is implemented to reduce redundant information, then storage and transmission efficiency improve, but power consumption increases due to additional processing
Solution Approach 1:
The patent applies preliminary action by performing modulation at the Nyquist rate before compression, which prepares the signal in advance to enable sub-Nyquist sampling. This preliminary modulation ensures that the signal contains sufficient information for accurate reconstruction while allowing for aggressive compression, thereby reducing data volume without requiring excessive processing power during compression.
Solution Approach 2:
The patent changes the sampling rate parameter from Nyquist rate to sub-Nyquist rate after modulation. This parameter change enables significant reduction in data volume while maintaining signal fidelity through the recovery unit. The modulation step transforms the signal characteristics so that sub-Nyquist sampling becomes viable, resolving the contradiction between data reduction and power consumption.
2Measurement precision
If ADC sample rate is increased to capture high frequency signals, then signal resolution improves, but power consumption and device size increase
Solution Approach 1:
The modulation unit performs preliminary action by modulating the input signal at or above the Nyquist rate before compression. This preliminary step embeds the high-frequency information into the signal in a way that allows sub-Nyquist sampling to capture all necessary information. The recovery unit then reconstructs the original signal with full resolution, achieving high measurement precision without requiring a high sample rate ADC, thus reducing power consumption.
3Loss of information
If transform coding is applied before compressive sampling, then signal representation improves, but processing complexity and power consumption increase
Solution Approach 1:
The patent extracts the essential information from the signal through modulation at the Nyquist rate, separating the critical high-frequency content from the redundant information. This extraction occurs before compression, allowing the system to focus computational resources on preserving only the essential information. The recovery unit then reconstructs the full signal from these extracted features, maintaining information preservation while reducing processing complexity by avoiding full transform coding.
Data Source
AI summary
A sensing and recovery system includes a sensing unit and a recovery unit coupled together. The sensing unit includes a sensor to generate a bandlimited continuous time analog signal, and a modulator coupled to the sensor to generate a modulated analog signal based upon modulation of the bandlimited continuous time analog signal at a modulating rate at least equal to a Nyquist rate for the bandlimited continuous time analog signal. A compressive sensing circuit is coupled to the modulator to generate a compressed sensed signal based upon conversion of the modulated analog signal at a sampling rate less than the Nyquist rate. The recovery unit recovers the bandlimited continuous time analog signal from the compressed sensed signal.