Velocity measurement errors were investigated for an array-based preclinical ultrasound scanner (Vevo 2100, FUJIFILM VisualSonics, Toronto, ON, Canada). Using a small-size rotating phantom made from a tissue-mimicking material, errors in pulse-wave Doppler maximum velocity measurements were observed. The extent of these errors was dependent on the Doppler angle, gate length, gate depth, gate ho...

Objective: Transesophageal echo-Doppler cardiac output as well as arterial pulse contour analyses cardiac output are increasingly used for cardiac output monitoring. No data are available whether both techniques may be used interchangeably in patients undergoing cardiac surgery. Design: Prospective, observational study Setting: Operating rooms of a university affiliated hospital. Patients: 30 p...

This paper derives Cramer-Rao bounds on estimates of the Doppler-shifted frequency of a coherent pulse-train intercepted at a single moving antenna. Such estimates are used to locate the emitter that transmitted the pulse train. Coherency from pulse to pulse allows much better frequency accuracy and is considered to be necessary to support accurate emitter location. Although algorithms for esti...

PURPOSE The aim of this study was to investigate factors that influence arterial Doppler waveforms in an in vitro phantom to provide a more accurate and comprehensive explanation of the Doppler signal. METHODS A flow model was created using a pulsatile artificial heart, rubber or polyethylene tubes, a water tank, and a glass tube. Spectral Doppler tracings were obtained in multiple combinatio...

Digital Signal Processing techniques for ground surveillance RADAR has been thoroughly investigated and optimized for an improved detection of target. Using the established techniques like Pulse compression, Fast Fourier Transform and Windowing, the present work optimizes the selection of pulse coding techniques, window type and different filters.The work proposes techniques to mitigate inheren...

Pulse Doppler radars suffer from range-Doppler ambiguity that translates into a trade-off between maximal unambiguous range and velocity. Several techniques, like the multiple PRFs (MPRF) method, have been proposed to mitigate this problem. The drawback of MPRF method is received samples are not processed jointly, decreasing signal noise ratio (SNR). To overcome drawbacks MPRF, we employ random...

When a target has a large velocity, the Doppler effect is not negligible. In that case, pulse compression by means of a linear frequency modulation suffers from significant signal loss in performance due to the mismatch between the reflected signal and the matched filter caused by the Doppler distortion. This problem can be avoided by using a hyperbolic frequency-modulated waveform, which has t...

background and aims. although salivary gland tumors are not very common, early diagnosis and treatment is crucial because of their proximity to vital organs, and therefore, determining the efficacy of new imaging procedures becomes important. this study aimed to evaluate the efficacy of magnetic resonance imaging (mri) and color doppler ultrasonography parameters in the diagnosis and differenti...