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28 Chapter 4: System Overview

PW Doppler Processing

Doppler processing includes both audio processing which presents Doppler signal in the form of stereo audio and

spectral processing which generates data for display of Doppler spectrum in the form of a scrolling spectrogram.

Doppler power spectrum is estimated performing Discrete Fourier Transforms on short, overlapped segments of

wall filtered Doppler signal. Doppler audio data is generated from wall filtered data by phase shifting the in-phase

component.PW Doppler Processing Function Block Diagram

Figure 4.3 PW Doppler Processing Function Block Diagram

QBP

Wall

Filter

Post

Gain

Resample Window FFT |.|

Temporal

Averaging

Compress

Baseline

shift

Display

Interpolate

Hilbert

Phase Shifter

Delay

indicates IQ pairs

Audio Output

Back

End

2x16 bits @ PRF rate

Audio

Gain

Audio

Gain

Peak &

Mean

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Edge Ultrasound System Wartungshandbuch Seite 36