Sub-Nyquist Signal Analysis with Frequency-Domain Phase Compensation
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Solution Overview
Problem
Conventional methods for increasing frequency resolution in multi-coset sampling systems require increasing the number of FIR filters, leading to a significant increase in circuit scale.
Innovation Solution
A signal analysis device with time-frequency conversion units, signal processing units for phase compensation, and a frequency estimation unit that collectively perform phase compensation and delay time difference cancellation in the frequency domain, allowing for increased frequency resolution without expanding the circuit scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of stages of FIR filters is increased to increase frequency resolution, then frequency resolution is improved, but circuit scale is significantly increased
Solution Approach 1:
The patent transitions the signal processing from time domain to frequency domain. By performing phase compensation and delay cancellation operations in the frequency domain instead of time domain, the system achieves high frequency resolution without requiring numerous time-domain filter stages, thus avoiding circuit scale expansion.
Solution Approach 2:
The patent changes the operational domain parameter from time domain to frequency domain. This parameter change enables the system to achieve precise frequency measurement through frequency-domain signal processing operations rather than through increased time-domain filtering complexity.
2Reliability
If phase compensation is performed in time domain using FIR filters, then phase compensation is achieved, but the number of filter stages must be increased significantly
Solution Approach 1:
The patent replaces the mechanical time-domain filtering approach with a frequency-domain processing approach. Instead of using multiple stages of FIR filters in the time domain, the system uses frequency-domain multiplication operations to achieve the same phase compensation effect with significantly reduced complexity.
Solution Approach 2:
The patent moves the phase compensation operation from the time dimension to the frequency dimension. This dimensional transformation allows phase compensation to be achieved through simple frequency-domain multiplication rather than complex time-domain convolution with multiple filter stages.
Data Source
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AI summary
A signal analysis device (100) includes: a plurality of time-frequency conversion units (40-1 to 40-4) that are each provided corresponding to one of a plurality of sampling sequences and convert a corresponding sampling sequence from a signal in a time domain into a signal in a frequency domain, the plurality of sampling sequences having been subjected to sampling performed at a sampling rate lower than a Nyquist rate from a plurality of signal systems generated by branching a signal of interest, and having received addition of delay times different from each other; signal processing units (50-1 to 50-4) that are each provided corresponding to one of the plurality of time-frequency conversion units (40-1 to 40-4) and collectively perform a phase compensation process corresponding to a sub-Nyquist zone of the sampling sequence that is a signal in a frequency domain output by a corresponding time-frequency conversion unit (40) and a process of canceling phase rotation caused by a delay time difference between the plurality of sampling sequences; and a frequency estimation unit (60) that estimates a frequency of the signal of interest by determining from which sub-Nyquist zone the signal of interest has been folded.