Doppler Signal Dealiasing Without Zero Insertion
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Solution Overview
Problem
Existing spectral Doppler systems face challenges in generating dealiased Doppler audio signals without distortion, leading to increased computation complexity and cost due to zero insertion methods, and existing methods either distort signals or require complex processing.
Innovation Solution
The method involves filtering quadrature Doppler signals using multiple filters in parallel branches, interleaving, and accumulating the outputs to obtain dealiased signals without zero insertion, reducing computational complexity and cost while avoiding signal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zero insertion method is used to generate dealiased Doppler signals, then signal aliasing is removed, but computation complexity and cost increase significantly
Solution Approach 1:
The patent extracts and removes the harmful zero insertion step from the conventional dealiasing process. By directly filtering the original Doppler signal without inserting zeros, the method eliminates unnecessary computational operations while maintaining the dealiasing effect through carefully designed filter coefficients.
Solution Approach 2:
The patent changes the filter parameters (coefficients) to compensate for the removal of zero insertion. The filter coefficients are specifically designed to achieve the same dealiasing effect that would otherwise require zero insertion followed by filtering, thereby reducing computational complexity while maintaining signal accuracy.
2Device complexity
If conventional filtering methods are used without zero insertion, then computation complexity is reduced, but signal distortion occurs
Solution Approach 1:
The patent modifies the filter coefficients to account for the absence of zero insertion. By carefully adjusting these parameters, the filter achieves the desired frequency response and dealiasing effect without distorting the signal, effectively compensating for the simplified processing approach.
Solution Approach 2:
The patent creates an equivalent filtering effect to the conventional zero-insertion method by designing filter coefficients that replicate the desired frequency domain characteristics, achieving the same result with direct filtering of the original signal.
3Reliability
If PRF is increased to avoid aliasing, then spectral alias is eliminated, but system cost and complexity increase
Solution Approach 1:
The patent changes the approach from increasing PRF (a system parameter) to modifying filter coefficients (a processing parameter). By adjusting the filter parameters, the system achieves aliasing prevention through signal processing rather than hardware parameter changes, thereby avoiding increased system complexity and cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for real-time processing of Doppler signals with reduced complexity and cost, producing dealiased signals without distortion, effectively addressing the limitations of previous methods.
Implementation Method 1
filtering quadrature Doppler signals using multiple filters in parallel branches
Implementation Method 2
ultrasonic signals are transmitted into a target area of a human body. The transmitted ultrasonic signals are then scattered by the cells of body tissue or those of blood flow in the target area
Data Source
AI summary
The present application provides a method for generating dealiased Doppler signals in a spectral Doppler system. The method comprises the steps of: filtering each of two quadrature components of obtained quadrature Doppler signals by using at least four filters in at least four parallel branches respectively so as to output eight signals, wherein the at least four filters for each quadrature component are equally divided into two groups, and outputs of each group of the filters are to be used for Doppler signals processing in one of forward and reverse directions, and coefficients of the different filters in each group can be interleaved with each other to form coefficients of a desired filter; interleaving and accumulating the output eight dealiased signals, according to direction and quadrature component of the output Doppler signals, to obtain forward and reverse dealiased Doppler signals F (t) and R (t).