IQ Demodulation
The IQ Demodulation Algorithm converts RF ultrasound channel data or general RF data into in-phase (I) and quadrature (Q) components by demodulating the fast-time axis (or y-axis). This is a key step in ultrasound signal processing, enabling envelope detection and further quantitative analysis.
Input
The algorithm is invoked with RF ultrasound channel data or general RF data as input, this can be either one or more images (for offline processing) or a stream (for online processing). For channel data, the relevant sampling and demodulation frequencies are determined automatically from the metadata. For general RF data, these parameters can be set manually.
Output
The output is a complex-valued image (I/Q data) representing the demodulated signal. This data can be used for envelope detection, Doppler processing, or other advanced ultrasound analysis.
Description
The IQ Demodulation Algorithm processes each frame of the input data, extracting the in-phase and quadrature components by mixing the signal with a reference frequency (usually the center frequency of the ultrasound pulse) and applying optional decimation. This operation shifts the signal to baseband, making it easier to analyze and visualize.
The algorithm supports automatic parameter selection for channel data, but all parameters can be customized for advanced use cases. Efficient, parallel processing is supported for large datasets.
Algorithm Options
The following options are available in the Controller for the IQ Demodulation Algorithm:
Sampling Frequency: Sampling frequency of the input image in the y-direction (MHz). Determined automatically for channel data, or set manually for general RF data.
Demodulation Frequency: Frequency of the signal to demodulate (MHz). Usually the center frequency of the ultrasound signal. Determined automatically for channel data, or set manually for general RF data.
Decimation Factor: Factor by which to downsample the data during demodulation.