Cosine Window Signal Processing for Sidelobe and Resolution Trade-Off
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Solution Overview
Problem
Window functions in existing signal processing technologies, such as the raised-cosine window, face a trade-off where reducing sidelobe components in the frequency domain leads to a decrease in frequency resolution.
Innovation Solution
A signal processing device that uses a window function synthesized from one or multiple cosine function terms, where a negative coefficient is applied to selected cosine terms to set a zero value at the center of the window range, thereby reducing sidelobe peak power and maintaining or improving frequency resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a raised-cosine window function is used to reduce sidelobe components in the frequency domain, then sidelobe peak power is reduced, but frequency resolution deteriorates
Solution Approach 1:
The patent changes the parameter of the cosine function coefficient from always positive to including negative values. Specifically, the window function uses coefficients that alternate in sign (e.g., +1, -1, +1, -1 pattern) to create zeros at specific frequency points while reducing sidelobes, thereby improving frequency resolution compared to traditional raised-cosine windows that only use positive coefficients
Solution Approach 2:
The patent combines multiple cosine function terms with alternating signs to create a composite window function. This composite structure (e.g., combining cos(2πx) with negative cos(4πx) and positive cos(6πx) terms) achieves superior sidelobe reduction while maintaining frequency resolution by creating destructive interference at sidelobe frequencies while preserving the main lobe structure
Data Source
AI summary
A signal processing device includes: a signal acquisition unit that acquires an input signal; a signal extraction unit that extracts a specific signal by multiplying the input signal by a window function; a frequency conversion unit that performs frequency conversion on the extracted signal; and a signal output unit that outputs the frequency-converted signal, in which the window function includes one or a plurality of cos function terms in which at least one of the sign of a coefficient to multiply a cos function or a degree of the cos function is set in such a manner that both frequency resolution and a reduction amount of sidelobes fall within allowable ranges.