Title :
Nonlinear receiver compression effects on the amplitude distribution of backscattered ultrasonic signals
Author :
Waag, Robert C. ; Demczar, Barbara A. ; Case, Timothy J.
Author_Institution :
Rochester Univ., NY, USA
fDate :
7/1/1991 12:00:00 AM
Abstract :
Nonlinear receiver compression effects on the amplitude distribution of backscattered ultrasonic signals were investigated using digitized RF signals compressed using an ultrasonic B-scan imaging instrument. Amplitude distributions of compressed RF and video signals were obtained from regions of B-scan images that approximately correspond to the same physical region in a random medium model with known backscatter amplitude characteristics. The amplitude distribution of the signal before compression was obtained by using a table constructed from measurements of the imaging instrument compression characteristics as a function of time gain compensation. While the results indicate the general form of the decompressed data agrees with single-parameter-model curves predicted by a widely used Gaussian random process model, the signal-to-noise ratios of the decompressed envelope vary by up to 20% from the value predicted by that model. This implies that effects such as nonlinearities, envelope smoothing, and noise can cause appreciable departures from theoretical data even under highly controlled conditions.
Keywords :
acoustic imaging; backscatter; biomedical ultrasonics; Gaussian random process model; amplitude distribution; backscattered ultrasonic signals; decompressed envelope; digitized RF signals; envelope smoothing; medical diagnostic imaging; nonlinear receiver compression effects; random medium model; signal-to-noise ratios; single-parameter-model curves; ultrasonic B-scan imaging instrument; video signals; Backscatter; Gain measurement; Image coding; Instruments; Predictive models; RF signals; Radio frequency; Time measurement; Ultrasonic imaging; Video compression; Automatic Data Processing; Data Collection; Data Interpretation, Statistical; Models, Structural; Signal Processing, Computer-Assisted; Transducers; Ultrasonics;
Journal_Title :
Biomedical Engineering, IEEE Transactions on