Ultrasonic Apparatus Chirp Signal Attenuation Correction
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Solution Overview
Problem
Current ultrasonic diagnostic systems face challenges in accurately measuring frequency-dependent attenuation coefficients in living tissues due to variations in tissue impedance and depth, leading to errors in ultrasonic reflection echo intensity and complex processing requirements, which complicates the comparison of ultrasonic image luminance across different sites.
Innovation Solution
The ultrasonic apparatus employs up-chirp and down-chirp waveforms to simplify the measurement of frequency-dependent attenuation by calculating the time difference between received signals, allowing for correction of signal amplitude and frequency, thereby reducing the influence of attenuation and improving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency analysis methods (FFT) are used to measure frequency dependent attenuation coefficient, then measurement capability is provided, but sufficient data sets cannot be secured due to tissue variation and unknown beta values
Solution Approach 1:
The patent changes the fundamental parameter from using unknown beta values with frequency analysis to using known chirp signal parameters (frequency sweep rate, bandwidth) to directly calculate attenuation. By transmitting signals with controlled frequency variations and measuring the received signal characteristics, the system eliminates the need for multiple data sets and unknown tissue parameters.
2Length of stationary object
If broadband pulse wave is used for imaging, then deeper ultrasonic reflection echoes can be received, but the center frequency is reduced due to frequency dependent attenuation
Solution Approach 1:
The system uses feedback by measuring the actual received signal characteristics (amplitude and phase) and using this information to calculate the frequency dependent attenuation coefficient. This measured attenuation information is then fed back to correct the received signals, compensating for the center frequency reduction and enabling accurate deep tissue imaging.
3Measurement precision
If mixing frequency is adjusted to center frequency for good S/N ratio, then signal quality is improved, but the unknown beta value prevents accurate adjustment
Solution Approach 1:
The patent performs preliminary measurement of the frequency dependent attenuation coefficient using chirp signals before the actual imaging process. This preliminary information is then used to pre-set the optimal mixing frequency for quadrature detection, eliminating the need for complex real-time adjustments and ensuring good signal-to-noise ratio from the start.
4Measurement precision
If frequency analysis methods are used to measure and correct center frequency, then Doppler measurement accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent replaces complex frequency analysis processing (FFT, spectral moments) with a simpler calculation method based on chirp signal theory. By using the known relationship between chirp signal parameters and the measured attenuation, the system achieves accurate center frequency correction and Doppler measurement without requiring computationally intensive frequency analysis.
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 enables simplified calculation of frequency-dependent attenuation coefficients and correction of received signals, enhancing the accuracy of ultrasonic imaging and allowing for more effective comparison of image luminance across different sites, improving diagnostic utility.
Implementation Method 1
transmits and receives an ultrasonic wave to and from an object
Implementation Method 2
the ultrasonic wave is affected by a frequency dependent attenuation (FDA) along with a propagation of the ultrasonic wave
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An ultrasonic apparatus has a pulse transmission and reception unit (2,4), an envelope curve detection unit (25), a time difference detection unit (27), and an attenuation characteristic obtaining unit (29). The pulse transmission and reception unit transmits a first transmitted pulse that a frequency increases with time and a second transmitted pulse that the frequency decreases with time, further receives a first received pulse corresponding to the first transmitted pulse and a second received pulse corresponding to the second transmitted pulse. The envelope curve detection unit detects a first envelope curve based on the first received signal and a second envelope curve based on the second received signal, respectively. The time difference detection unit detects a time difference between the first envelope curve and the second envelope curve. The attenuation characteristic obtaining unit obtains a frequency dependent ultrasound attenuation characteristic based on the time difference.